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Coastal Zone information COASTAL ZONE Center INFORMATION CENTER A D 730 769 NATIONAL 8HORELINE STUDY. HAWAII REGIONAL INVENTORY Corps of Engineers Honolulu, Hawaii August 1971 DISTRIBUTED BY: National Technical Information Service GB U.S. DEPARTMENT OF COMMERCE 458.62 .H3 5285 Port Royal Road, Springfield Va. 2215 U55 1971 This document has been approved for public release and safe t COASTAL Z ONE INFORMATION CENTER. 1jawall, Regional. Inventory 'OF THE @.Watloaaf Shorell e Study r). E), -C (I s. 0 FA P.J1V:F.N T@ .(),.P OM VERC E F1 .1 CC)A@,-.'7.@. SEPv'1CE(: CENTER.: 2 23 6'S() Ll I HH(11F@ON AVENUE OGT ChAmILLSTON SC 29405w-2413 1)1 Vm@ GOD. 1C -1:11 for PubL r,e OCL" ution Uturdtad R, Reproduced by V,D 14ATIONAL TECHNICAL q. INFORMATION SERVICE. Sprin0eld, Va. 22151 ROBIN U.S. ARMY ENGINEER DIVISION Pacif ic Ocean Xty Of CSC-Libr Corps of Engineers. ary .3. Di te L& 1b HONOLUL HA All U. AUGUST, 1971 UPI WHITE SEMON CLIFF SECTION JUSTIFICATION By 0 lid f ;sr.IAV -7o, @:-Howmill the:shore,@ bi SHORE -MAN AGE,MENT GUIDELINES Whatis its. Condition 41@ 12@ JN REGIONAL VENTORYREPORTS What can be done,.? ce'the-shore jo -preserve, orenhan Uslng,@_, ..by iques- 't `hii Engineering ec -P SHORE. ROTECTION GUIDELINES REGIONA L INVENTORY. REPORTS b -0 ..m.an agement. tec" hniques@. SHORE. MANAGE MENT. GUIDELINES S&4 In' 1968, the 90th Congress authorized this National appraisal of shore erosion and shore @rotection needs. This National Shoreline Study and the existing Federal shore protection programs recognize beach and shore erosion as problems for all levels of government and all. citizens. To satisfy the purposes of the authorizing legislation, a Jamily of 12 related reports has been published. All are available to concerned individuals and organizations in and Out of government. Regional Inventory Reports (one for each of the 9 major drainage areas) assess the nature and extent of erosion; develop conceptual plans for needed shore protection; develop general order-of- magnitude estiniates of cost for the selected shore protection; and. identify shore owners. Shore Protection Guidelines describe typical erosion control meaSLOVS and. prc- sent examples of shore protection facilities, and present criteria foi- planning shorc protection programs. Shore Management Guideiines'provide, information to assist decision n-iakers to dcvelop and implement shore management programs. Report on the National Shoreline Study, addressed to the Congress; stintinarizes. the findings of the study and recommends priorities among serious problem areas for action to stop erosion. Det ails'. Of fliustrationg In, this" document may' be better Istudied on microfiche STATE OF HAWAII Regional. Inventory Report Details of illistrations IN this document may be better studied on microfiche Prepared by U.S.Army Engineer Divsion, Pacfic Ocean Corps of Enginers Building 96 Fort Armstrong Honolulu Hawaii 96813 LIST OF FIGURES 4 Figure Tide I Makahuene Point, Kauai (Camera Hawaii Photo), 2 One of several beaches. at Poipu, Kauai 3 Barking Sands area; Kauai 4 Kailiu Point and Hanalei Bay area, Kauai (Camera Hawaii Photo 5 Anahola Beach, Kauai (Camera Hawaii Photo) 6 Rocky coastline between Hanauma Bay (lower left) and. Wawamalu Beach Park (Upper left). Oahu 7 Undermined coconut tree at Hanauma Bay Bea 8 Restoration of thebeach at Hanauma Bay Beach Park, Oahu 13 Aerial view of Waikiki Beach 14 Eroded conditions of the Kuihio Beach sector of Waikiki Beach 15 Man-made Duke-Kahanamoku Beach 16 Aerial view of Ala IVA Boat Harbor and Magic Island Oahu 10 18 Aerial view of Haleiwa Harbor,and Haleiwa Beach Park, Oahu 19 Damage to a section of,the coastal highwayalong Kaiwailoa Beach, Oahu 21 Aerial view of Kaaawa Beach,Oa 22 Aerial view of the shoreline between Kaupo Beach Park and Makapuu Point, Oahu] 23 Aerial view of Kaunakakai Barge Harbor, Molokai 24 Papohaku Beach, Molokai 25 Sea stack and steep seacliffs along the norheast coast of Molokai 26 Aerial view of seacliffs along northeast coast of Molokai(Camera Hawaii Photo) 27 Aerial view of Manele Harbor, Lanai 28 Aerial view of Lahaina Boat Harbor, Maui 29 Aerial view of Kaanapali Coast, Maui (Camera Hawaii Photo) 30 Flemings Beach, Maui (Camera Hawaii Photo 31 Effects of the tsunami of April 1, 1946 on the waterfront business area of Hilo, Hawaii 32 Destruction along a section of Hilo Bay resulting from the tsunami of April 1,1946 33 Aeril' view of Kaimu Beach on the island of Hawaii 34 Exposed lave rock and boulders at Kaimu Beach 35 Undermined coconut tree at Kaimu Beach 36 Hookena Beach, Hawaii 37 Resort development along the Kona Coast, Hawaii 38 Disappering Sands Beach during the winter (West Hawaii Today Photo) 39 Disappearing Sands Beach during the summer (West Hawaii Today Photo) 40 Hapuna Beach, Hawaii 41 Pololu Beach, Hawaii 42 Waipio Beach, Hawaii vii LIST OF TABLES Table Title Page Shoreline Land Ownership, State of Hawaii 5 2 Shoreline Land Use, State of Hawaii 6 3 Shoreline. Characteristics, Island of Kauai 15 4 Shoreline Land use, Island of Kauai 15 5 Shoreline Land Ownership, Island of Kauai 16 6 Characteristics of Principal Beaches on Kauai 17 7 Shoreline Characteristics, Island of Oahu 31 8 Shoreline Land Use, Island of Oahu 3 9 Shoreline Land Ownership, Island Of Oahu 10 Characteristics of Principal Beaches on Oahu 32 Shoreline Characteristics, Island of Molokai 53 12 Shoreline Land Use, Island of Molokai 53 13 Shoreline Land Ownership, Island of Molokai 53 IT Characteristics of Principal Beaches on Molokai 54 15 Shoreline Characteristics, Island of Lanai 65 16 Shoreline Land Use, Island of Lanai 65 17 Characteristics of Principal Beaches on Lanai 65 18 Shoreline Characteristics, Island of Maui 73 19 Shoreline Land Use, Island of Maui 73 20 Shoreline Land Ownership, Island of Maui 73 21 Characteristics of Principal Beaches on Maui 74 22 Shoreline Characteristics; Island of Hawaii 87 23 Shoreline Land Use, Island of Hawaii 87 24 Shoreline Land Ownership,Island of Hawaii 87 25 Characteristics of Principal Beaches Hawaii 88 26 Suitable Beach Erosion Control Measures 104 27 Authorized Federal Projects for Hawaii 106 Authorized Federal Studies for Hawaii 107 LIST OF PLATES Plate Tide Page 1 State of Hawaii 10 2 Beach Profile 11 Hauula Beach Park Oahu 3 12 4 Waialae Beach Park, Oahu. 13 5 Sunset Beach, Oahu 14 6 Shoreline Physical Characteristics, Island of Kauai 24 25 7 Shoreline Land Use,1sland of Kauai 26 8 Land Ownership Island of Kauai 27 9 shoreline Erosion Areas,Island of Kauai (southern half) 28 10 Coral Reef, Island of Kauai 29 11 Shoreline Erosion Areas Island of Kauai (northern half) 30 12 Shoreline Physical Characteristic Island of Oahu 47 13 Shoreline Land Use, Island of Oahu- 48 14 Land Ownership, Island of Oahu, 49 15 Shoreline Erosion Areas, lsland Oahu (southern half) 50 16 Coral Reef, Island of Oahu 51 17 Shoreline Erosion Areas, Island of Oahu (northern half) 52 18 Shoreline Physical Characteristics Island of Molokai 19 Shoreline Land Use, Island of Molokai 58 20 Land Ownership, Island of Molokai 59 60 21 Shoreline Erosion Areas, Island Molokai (southern half) 61 22 Coral Reef, Island of Molokai 62 23 Shoreline Erosion Areas, Island of Molokai (northern half) 63 24 Shoreline Physical Characteristics and Shoreline Erosion Areas, Island of Lanai 68 25 Shoreline Land Use, Island of Lanai 26 Land Owneship, Island of Lanai 70 27 Coral Reef Island of Lanai, 28 Shoreline Physical Characteristics Island of Maui 71 29 Shoreline land Use, Island of maui 81 82 30 Land Ownership,Island of Maui 31 Shoreline Erosion Areas , Island of Maui (northern half) 83 32 Shoreline Erosion Areas, Island of Maui (southern half) 84 85 33 Coral Reef Island of Maui 86 34 Shoreline Physical Characteristics, Island of Hawaii 97 Plato Tide Page 35 Shoreline Land Use Island of Hawaii 98 36 Land Ownership, Island of Hawaii 99 37 Shoreline Erosion Areas, Island of Hawaii (eastern half) 100 38 Shoreline Erosion Areas, Island of Hawaii(western half) . 101 39 Conceptual plans for typical Hawaiian Beach on Shallow Reefs 110 x INTRODUCTION The shoreline is one of Hawaii's most valuable. passed by the Congress in recognition of the critical assets. As an island state, Hawaii is heavily dependent problems facing the Nation's shoreline and the need on the deepwater, harbors, along its shoreline, for for coordinated effort and a National comprehensive exportation of its agricultural and manufactured state and local governments in solving plan to assist state and local governments in solving products to overseas markets, and for importation these problems. of raw materials and other commodities for: local consumption In addition, the shoreline is the,State's most valuable recreational resource. Residents and visitors alike, gain much. pleasure from relaxing on SEC.106. (a) The Chief of Engineers, Department the sandv beaches, fishing and snorkeling in the of the Army, under the direction of the Secretary of the Army shall make an appraisal investigation nearshore waters, and surfing on the rolling waves. Development of the shoreline in the past shaped and study, including a review of any previous relevant major elements of the, State's economy. However, studies and reports, of the Atlantic,Gulf, and Pacific current shoreline development resulting from rapid. coasts of the United States the coasts of Puerto obanization, an expanding tourist industry, and Rico and the Virgin Islands, and the shorelines of growing population with increased leisure time and the Great Lakes, including estuari es and bays thereof. income, is reaching unanticipated proportions. Al- for the Purpose of (1) determining areas along such though developments along the shoreline have. gen- coasts and shorelines where significant erosion oc- erally been accomplished to meet demands for rec- curs; (2) identifying those areas where erosion pre- reational beach facilities; they must be judiciously sents a serious problem because the rae of erosion. planned and developed to assure that, shoreline considred in conjunction with economic, industrial, resources would not be irretrievably lost to future recreational, agricultural, navigational, demographic_ generations. ecological, and other relevant factors, indicates that The anticipated growth of the State's population, action to halt such erosion may be justified; (3) des- economy, and water-oriented recreational activities, describing generally the most suitable type of rernedial and the decrease in open land. areas are expected to action for those areas that have a serious erosion result in increased arid often conflicting demands-, problem; (4) providing preliminary cost estimates. for shoreline resources. However, these :Precious for such remedial action; (5) recommending priorities resources,are finite and must therefore be judiciously among the serious problem areas for action to stop utilized if they are to remain for. the benefit and qen- erosion; (6) providing State and local authorities joyment of present and future generations. Only with, with information and recommendations to assist the. knowledge of what the shoreline is, has been, and creation and implementation of State and local could become, can sound planning be accomplished coast and shoreline erosion programs; (7) developing to ensure against costly irreparable mistakes, and, recommended guidelines for land use regulation in to reap optinium benefits from the limited shore- coastal areas taking into consideration all relevant line resources throu h rational,choice between factors; and (8) identifing coastal areas where competing Uses and effective solutions to shoreline title uncertainty exists. The Secretary of the Army problems. This report which summarizes the results shall submit to the Congress as soon as practicable, of the regional shoreline inventory for the State of but, not later than three years after the date of enact- Hawaii provides some of the needed information by ment of this Act, the results of such appraisal inveti- describing the present condition of the State's shore- gation and study, together with this recommendations. line, by &fining the. scope and, magnitude Iof shore-: The views of concerned" local State, anti, Federal line problems and by Identifying areas where more authorities and interests will be taken into account research and knowledge of our coastal environment . in. making such appraisal investigation and study. are required in order, to better assess long-term consequences of natural a changes, to the shoreline. The regional inventory. was accomplished. Under the authoritv The Chief of Engineers report. summarizing tile, of Public Law 90-483 (1968 River and Harbor Act). findings of the National Shoreline Study, including This legislation, which is quoted below, those presented in this report, was submitted to the conduct Of the National Shoreline. Study Congress in August 1971. GENERAILPROCEDURE This report presents the results of an inventory of on the above criteria. However, only those areas the shoreline of six of the eight principal islands -which have been- investigated or for which immediate of the State of Hawaii,. The.islands of Kahoolawe and*,. action is considered necessary are discussed in de- .'Niihau are excluded because their shorelines,are.not tail in text. legally accessible to the general public. Emphasis is- placed on shorelines within developed ar .easl- sho Ire- Non-crifical erosion sections are defined as those -reaches where erosion is considered -to' be more .lines remote from population centers and. inaccessible I . shorelines are, not discussed.in detail. Emphasis . w conducive to solution by effective shoreline manage- ment methods than by physical improvements. In- also. plated on the identification of problem areas, 1, c uded in this category are areas ..where erosion is rather than on problem solution. Therefore, remedial- expected to continue such that within 15 to , 50 actions suggested in this report are. limited to con. ..years, the area,would be Similar to those Considered ceptual plans @%Yhich_ Are intended to provide general. critical in this report. Non-critical erosion areas are. guidelines on suitable protection measures for Hawai- not considered t6 be less si nifi6nt than critical ero- ian shores. 9 Sion areas. On the contrar'%, these Areas are probably th. preparing (his report, maximum, use was made of' more important for planning purposes because the .available information from..previous studies and re- fture cond'tion of these areas is dependent on expe- u l ...ports prepared bN the State of Hawaii, the Corps of ditious implementation of effective coastal zone. Engineers, and other governmental and private management procedures. in recognition of this., agencies.,In particular, information from "Hawaii's Shoreline" I(State of Hawaii Department of Planning problem, the Chief of Engineers has published. a. general report, "Guidelines on Shore Management" and Economic Development, 1965) and "Hawaiian which includes reference material on multiple uses of Beach Systems" (Hawaii Institute of Geophysics the shore, principles of comprehensive planning and Report HIG 64-2,,1964) @were extensively used. The information from these reports served as the base zoning, and other non-structural alternatives to shore: erosion problems. Another report, "Shore Pro- from which tabulations were made of shoreline.para- tection Guidelines", describes. typical methods of meters reqluired for the Chief of: Engineer's report shore erosion control, both Structural and non-struc- to the Congress. Although the inventory relied heavily tural-, discusses the merits and shortcomings of on available data from previous, studies, it differs various, shore protection facilities with. special rie@, from these studies in, that it not only, describes the ference to their impact on the environment,, and physical characteristics of the shoreline, but. also presents @ criteria for designing and using protective provides information on problem areas, particularly .,'in the mea,sures. These reports are intended to assist State beach erosion.. Shoreline mileages diK.,ussed and local authorities-and interested parties plan and report are based on maps prepared,for the "Hawaii' IS .implement effective shore protection programs. .Shoreline" report. In'this report, critical, erosion areas are defined as those reaches where erosion presents a serious problem because the rate- of erosion,- considered in conjunction with economic, industrial, recreational, agricultural, navigational, demographic, ecological, and other relevant, factors, indicates, that-action to halt -such erosion may be justified., These areas in'. Aude recognized problem areas. for which reqpests: for remedial action have been received. by the Corps of Engineers from State and county government agencies:, reaches where concern has been expressed ,b-,- interested citize@ns, arid civic, organizations; arid reaches: where anah-sis of existing and past shore line conditions indicate existence of a, serious problem in view Of Current and future use of the. Area. For. each of the six islands, the report -lists the Areas which "are considered to be criticallN cioding based 3 PRECEDING, PAGE BLANK GENERAL DESCRIPTION. OF THE STATE GEOGRAPHY above the mean high water mark in 1962. Shore- The, Hawaiian Islands extend some 1,700 miles line,ownership has not changed significantly since over the North Pacific Ocean and are part of a that time, therefore the data in table I are considered volcanic mountain range, most of which is sub- to generally reflect current conditions. The relatively merged. At the highest part of the range a number. stable situation surrounding shoreline land owner- of large peaks protrude above Sea level, and. con- ship is attributed to the tremendous demand for the stitute the. major islands of the State of Hawaii,.. islands limited beach frontages, particularly sandy which is the. 50th state admitted to the Union, the reaches, which has in effect discouraged sale of 47th in size, and 40th in population. these valuable lands. The eight principal islands. of the State, from north to South, are Niihau, Kauai,Oahu, Molokai Lanai, Kahoolawe Maui, and Hawaii (plate 1). The Table I Shoreline Land Ownership islands form a, 400-mile-long are at,the south- State of Hawaii eastern end of the archipelago, and comprise more than 99 percent of the State's land area. These islands. Owner Total, Shoreline Sandy Shoreline were formed by, Successive flows of basaltic lavas, %of which erupted first from vents in the ocean floor and Miles Total Miles Total later from craters and fissures as the lava domes Federal ....... ............... 106.7 11.1 13.5 7.3 rose above sea level. Of the eight islands, Kahoolawe public(non-Federal) ......... 267.0 28.5 50.0 27.0 is uninhabited, and under military control; Niihau is private ......... 560.7 60. 1 121.4 65.7 privately owned and little developed., The other SIX Total.. .............................. 934.4 100.0 184.9 100.0 islands therefore constitute the heartland of the State. smalll offshore islands excluded, except Sand Island and The coastline of the state varies greatly in physical For Island. characteristics from island to island, and from one Source:Hawaii's Shoreline" district to another on the same island. The volcanic Hawaii Department of Planning and Economic origin and mountainous nature of the islands, how- ment in 1965. ever, result in a predominantly bold and rugged coastline with few naturally protected bays or inlets. Towering cliffs rise steeply from the sea to heights Although most of the shoreline below the high of 1,000 feet or more along. the northwest coast of water mark are public lands, open to all, access to Kauai and much of the north coast of Molokai. Lower these areas is generally restricted because of physi- but similarly precipitous cliffs prevail along the cal or legal Inaccessibility through abutting prop- Hamakua coast of Hawaii and in other areas of Ha- As shown in table I as much as 60% of the waii, Maui. and Lanai In contrast to the rugged lands abutting the shorelineis privately owned. and coastline, lowlying coasts with sweeping beaches are only about 28% is owned by the State and counties. extensivelv developed in some areas, particularly on Unless some form of right-of-way through private Maui, Oahu, and Kauai. lands is available, the shoreline abutting these Another type of coastline is. found extensively along properties is not accessible to the general Public. the east and north sides of Oahu, the, south coast of In addition to legal inaccessibilty, much of the Molokai, and the north coast of. Lanai. Created by state's shoreline is physically inaccessible or only inshore and barrier coral reefs, the shoreline in marginally accessible. About 64% of the shoreline, is hese areas is usually low and rocky with occasional I comprised of Igneous lava. basalt. which rises from the small pocket beaches or an intermittent low shore edge in clifflike formations such that the interrupted by bold headlands. abutting shoreline is either physically inaccessible or marginally accessible tiding on the steepness SHORE OWNERSHIP AND ACCESSIBILITY f the cliffs. Many marginally accessible areas are In Hawaii. title to all shoreline below the used for water- orientcd recreation primarily by rest- water mark rests with the state government dents who enjoy fishing and diving from the cliffs such title has, been,specifically withheld by the- and collecting shellw opihi (type of shell fish) and Federal Government or has been transferred to pri- vate holdings by legal instrument or by prescriptive limu (edible seaweed) along the rocky faces right. Table I summarizes the ownership of land The State and county governments recognize the value of the shoreline to the socio-economic enviro- PRECEDING PAGE BLANK merit of the islands, and are striving to increase an increase of 22 miles since 1962. I'vlosi of the newly accessibility to tht. public shores through acquisition developed shorefint. re-aches were 'previously Coll- of niore public easements and rights-of-way. In addl- scrvation or opcil undc%-cloped land. The continucd tion, the State of Hawaii has enacted a provision increase In Population and leisure tinic, and expan- requiring that public beach rights-of-way be reserved sion of the tourist inclust 'ry place greater emphasis Oil when public lands along the coast are disposed of. the need for more recreational and resort facilities.. Also, in June 1970, a State law was passed requiring Therefore, recreational beach facilities are expected establishment of shoreline setbacks of not less than to be the major competitors for developable shore- 20 and not more than 40 feet inland from the high line reaches of the state. water mark. The law also prohibits removal of sand, coral, rocks, soil,, or other beach compositions for purposes other than reasonable domestic use. In addition, the State law prohibits construction of COASTAL'MATERIALS AND PROCESSES structures, other than those required for safety and Analysis of the coastal zone requires an under- shore protection purposes, within the setback area. standing of (1) the definition of its components, The counties within the State of Hawaii have also (2) the origin and composition of the materials with- enacted shoreline setback laws, some of which are more. restrictive than the State law. In the case of in this zone, (3) the natural processes acting on a conflict between State and county requirements, these materi ials, arid 0 @ . the interrelationship be- tween materials and pi '-ocesses over periods of time. the State law stipulates that the more. restrictive A complete, comprehensive understanding 'of the requirement shall be enforced., materials and complex processes along our coastal zone has yet to be attained. Much has been written on this subject, but much research conLinues. How- ever, because the mater lals and processes which have DEVELOPMENT OF COASTAL AREAS shaped Hawaii's coastline are unique, available infor- Shoreline uses in 1962 are summarized in table 2 mation on this subject is briefly discussed in this which shows that undeveloped land comprised the section to provide a better understanding of the re- largest use of the staWs shoreline. maining sections of the report. Definition of the Coastal Zone. The nomenclature Table 2 used in describing a coastal zone and coastal pro- Shoreline Land Use cesses are defined below and illustrated in plate 2. State of Hawaii' The shorelin'e is the intersection of the surfaces Land Us .e Total Shoreline Sandy Beach. of the sea with the land. Sea level varies about 2 %of %of feet each day in Hawaiian waters as a result of tidal Miles Total Miles Total forces, therefore the shoreline shifts along' the slope of the land as the-sea rises"and falls. The shoreline Recreational -Public ....... -93.7 10.1 22.7 12.3 as shown on the m-aps of this reppr't portrays . tide Recreational -Private ....... 4.5 0.@ 21.5 1.4 level at mean high water. Nori-recreational Development ................. 203.5 21.8 40.9 22.1 The shore is the strip of land bordering, and as a Undeveloped ..................... 632.7 67.6 118.8 64.2 rule, shaped by the sea. Total ................................. 934.4 100.0 184.9 100.0 The beach is a shore of unconsolidated material Such as sand, cobbles, and boulders. The beach.ex- 'Small offshore islands excluded, except Sand Island, Ford tends landward from the low water line (shoreline Island, and proposed reclamation of reef lands in the Keehi at low water) to the place' where there is a marked Lagoon and off Ala Moana Park ("Magic Island") , ... hange in material or physio .graphic form, or to the c Source: I "Ha%vaii's Shoreline" prepared by the State of line of permanent vegetation (usually the effective .1-lawaii Department of Planning and Economic Develop- limit of storm waves). Unless otherwise specified, menL in 1965. the seaward limit of a beach is the mean low water line. A beach includes a foreshore. arid backshorc. The @ fo resh ore is that part of the shore lying be- Si - 1962, local. governments have placed em-. t%vcen the crest of the seaward berm (or upper lunit phasis 67 development of the shoreline, particularly of wave wash at high tide) and (fie ordinary low sandy reaciles, for resort arid recreational uses. As a water rnark. It is that part of the short- which. is result, it is estimated that about 125 statute miles of ordinarily washed by thC L1131-1-ISh and backrLlSh of the' shoreline were in resort and recreational use in 1970, waves as the tides rise and fall. 6 The backshore is that zoneof the shore or beach elevated above the surrounding bottom of the sea, lying between the foreshore and the coast arid acted- generally submerged arid dangerous to surface upon by waves only during severe storms, especially navigation. when combined with exceptionally high water. Mean Lower Low Water. (MLLW) is the Average The reef, fringing is a reef attached to an Insular height of the lower low waters over a 19 year or continental shore. The reef, barrier is a reef which roughly parallels period. For shorter riods of observations,correc tions are applied to eliminate-known. variations and land but is some distance offshore, with deeper reduce the results to the eqivalent of water intervening. year value. The Littoral. means of or pertaining to a shore, The high water mark is the effective landward especially of the sea. limit of wave wash and is sometimes Marked by Littoral drift is the material moved in the littoral debris. The high water mark is normally the, seaward zone under the influence of waves and currents. limit of permanent vegetation.This term is of Littoral transport is the movement of material along the shore in the littoral zone by waves and currents. Tsunami is a long-period wave caused by an particular importance b3ecause it marks the boundary underwater sesimic disturbance such as volcanic between the publicly owned Hawaiian shores and eruption or earthquakes. Commonly misnamed "tidal privately owned uplands). wave. The inshore zone extends frmo th low water line Composition and Orgin of Coastal Material. In general, coastal material can be classified into one of three catergories-volcanic, biological and detrial, Most of the coastal zone is actually comprisedof combination of these material whichj are found in various shapes, sizes and stats of weathering and erosion. Although quartz sand is the most domiinant worldwide beach constituents it is absent from Hawai- ian beaches primarilly because it is not present in lava- basalt and is not formed in the weathering of basalt. Sea cliffs , rock and other material of volcanic orgin comprise about two-thirds of Hawaiis coast- line. Their prevalence is attrbuted to the fact that each of the Hawaiian Islands began as one or more volcanoes that were gradually built up from the sea floor by successive intermittent extrusions of basaltic lava. The volcanic formation of the islands generally occurred from the northwest down the island chain to the southeast, such that kauai of the chain. The suc Hawaii the youngest island of the chain. The suc cessive development of the islands and the recent volocanic activity generally inhibihts of the Islands Coastlines Of paticular significance is the fact that volcanic activity generally inhibits development of sand beaches in several ways: first a shorline may be travesed by a lava flwo on land cover an existing sand beach : second , the flow may destroy marine organisms which often produce calcareous sediment: third recent lava flows on land are highly permeable such that rain infiltrates into thelava rather than flow overland thereby eroding and transporting detrial sediments to the coast where they may nourish a beach: and finally a sec- tion of recent flows crossing the shorline must undergo extenxive marine erosion before a sea cliff or a broad platform is formed whereby waves cross- through the zone of breaking waves The nearshore zone extends seaward from the shoreline wll beyond the breaker zone. It defines the area of nearshore currents. The offshore zone for Hawaiian waters is defined as the zone extending seaward from the breaker zone to a water depth of about 600 feet. The 600- foot depth contour ranges from about 1 to 10 miles off shore of the islands. The coast is a strip of land of indefinite width (it may be several miles ) that extends from the shore- line inland to the first major change in terrain features. The coastal zone includes the land and sea area bordering the shoreline a s depicted on plate 2 and in the forgoing definitions. Critical erosion is defined as erosion which, when considered in conjunction with economic,industrial, ecological, and other relevant factors indicates that action to halt such erosion may be justified. Bedrock as used in this report generally refers to the relatively solid foundation uneerlying the char- acteristically shallow deposits of beach materials. The foundation can be solid coral reef structure, coral reef rubble beachrock, solid basalt, or basalt rubble. This term is also used to describe solid rock outcroppings Beachrock is straitified calcareous sandstoneor congolomerate common along many Hawaiian beaches. Its formation appears to be limitied to the beach zone. It can form rapidly as evidenced by the fact that fence wire and coke bottles are found cemented in the rock. Older beachrock which formed at different sea levels of the geologic past are found at elevations higher and lowee than present sea level. The reef is a chain or range of rock or coral, ing the reletively flat area will lose enough energy and Lanai Plate 4 Shows the beach and reef con- to permit a beach to form and grow. figuration at Walalae. Beach Park oil In the South Shore athough volcanic activity Usually inhibits beach of Oahu. development, it sometimes creates beautiful, rare The reef surfaces: off the northern and Some black sand beaches such as those on the southeast leeward coasts are Much more irregular and deeper coast of the island of Hawaii which has the only two than those off of windward and. protected coasts. active volcanoe's in the state. These beaches are The beaches behind the north coast reefs of Oahu formed by the successive explosion and chilling which are armong the finest on the island. Plate 5 shows the occurs when molten lava enters the ocean. beach and reef configuration at Sun-set Beach on the Coastal material of biological origin primarily north shore of Oahu. Consists of calcareous sand and coral reefs.The light- In addition to material of direct volcanic and bio- colored grains ofcalcareous sand found around the logical origin, Hawaii,s coastline contains detrital islands are fragments of skeletal parts of inverte- sediments, the result of weathering and erosion of brate animals and algae that lived and died in the sea. the hinterland. Detrital sediments are usually (lark Similarly, coral reefs are wave-resistant marine brown in color. They are primarily removed from land structures which are built in Hawii and other warm by strearms and are deposited where the streamflow environments by shallow-water organisms. The reefs slackens as, it enters the ocean forming bars, usually consist of a skeleton or framework of corals barriers, and deltas, or mixing with other material along the shore. On coasts exposed to moderate and coralline algae. They are another important fac- or in the coastal processes of the Hawaiian Islands in wave action, the sediment is worked back and forth that thev not only contribute calcareous material to in the shallow water,and on the beaches, and often form and nourish beaches, but also protect these forms submerged bars or exposed, barriers at the beaches from damaging wave action. In general,the stream Mouths. Also._Sediment may drift away from better sand beaches of the state lie behind well then, strearm-mouth sources as as result of nearshore developed reef formations As such the older islands, currents and in may form beaches, shallow-water Sand Kauia and 0ahu which have more developed reef patches, and ridges of sand and gravel along nearby reaches. systems. have more calcareous beaches than does Shore Processes: The shifting of sand along the comparatively fewer reefs.' coasts of. the islands movement of Sand on and Coral reefs are able to exit in the wave zone be- off shores, and, any other behavior of sediment in cause of then massive structure and their ability to the nearshore or coastal zone of, the islands are the repair storm damage by new growth. Reefs which result Of sorme force or source of energy. Although are connected to the shore are called fringing reefs all of tile sources of the energies reachinig the Hawai- and are the most prevalent type in Hawaii The ian Islands have not been identified the followiing characteristics of these reefs vary with wave exposure sources are thought to be responsible for the most of the and, in general, are wide and shallow off. windward- energy found in the nearshore zone of tile islands:. coasts, wide and verv shallow along some leeward a. Ocean waves, and currents or otherwise protected coasts, and deeper and more b. Atmospheric winds irregular off northern coasts. c. Tsunamis Tile reefs fringing the windward coasts of Kauai Ocean waves and currents are believed to be and Oahu are shallow with outer edges.frorn 2 to 12 responsible for almost all, of the enegy which con- feet below low tide. From Kahuku to Kaneohe Bay tributes to deformation of' beaches and transportation on Oahu the reef is about 1,000 feet wide and is of sediment along the coasts of the Hawaiian Island crossed by numerous 30-foot-deep. channels with Depending on the magnitude and direction, of the sandy bottoms. The windward coasts typically have waves and Currents reaching the shoreline sand may poorly sorted fine-grained calcareous sediments on move onshore and offshore as it does at Disap- narrow beaches. Plate 3 Shows. tile beach and reef pearing Sands Beach near KailuaM Hawaii or back Configuration at Hannula Beach Park onthe windward and forth along the shore as at Limahar Beach,Kauai shore of Oahu. Atmospheric winds, particuularly the Northeast The shallowest and flatters reef found off' Trades an the Kona winds are also important protected coasts . Commonly they have volcanic sources of energy along the coasts of the Island grains mixed in the domainantly clacereous poorly The Northeast Trades generally prevail from April sorted sands and gravels covering them. Their to November and have average velocities of about 10 I adjacent beaches are the narrowest beaches in the to 20 miles per hour from the northeast or east. These islands. This type of reef is found on the south winds remove large quanties of sand from th near- coast of Oahu from Koko Head to Pearl Harbor and shore zone by blowing them inland to form dunes. Kona winds which prevail during November through rims the protected water between Molokai. Maui. 8 March frequently have belocities in excess of 25 miles seasons of the year. reflecting the seasonal variaitons per hour However. they are less persistent than the in the amount and types of wave energy that reach Northeast Trades and are therefore less effective ill the beaches. Therefore this phenomenon is often the movement of coastal sand. referred to as seasonal accretion and erosion. Tsunamis are trains of long-pe riod waves which Long-term and often relatively permanent changes are impulsively generated in the ocean. Although to the shoreline have both natural and man-made occurring infrequently, they ate a source of very high causes. A principal natural cause is the gradual energy which, upon reaching the coasts of the islands, change in the type and magnitude of energy factors are usually extremely destructive, to the sho reline reaching the shoreline. The changes in energy factors and to. developments along the coast. could cause shifting of sand either along the coast., Relationship Between Coastal Materials and or onshore and offshore, and the transportation of Processes. Beaches are. not, static, but are con- sand to deep water it here it would normally be tinuly changing their compositio n, structure, and lost to the nearshore beach system. Other natural volume seasonally ,yearly, or over longer periods of causes include wnds and storms which often remove time. Beach changes are not isolated phenomena, but sand from the nearshore system and deposit it inland a result of the complex interrelationships between. of the normal shoreline area. coastal materials and processes over periods of time. Shoreline changes caused by man include thc Certain relationships between the beach and its removal of more sand from a particular beach than surroundings bring about a net increase in the volume can be replenished by natural processes, interferences of the beach, or beach accretion. Other. relationships with the source of sand for a beach by dredging result in a net loss of sand from the beach, or beach through reefs, and construction Of Stutures along erosion. Also a combination of accretion and erosion the shoreline. In addition, population of nearshore may Occur such that a beach is in a continual state of Waters can also ultiatley affect natural, sources of flux, accreting at some times, eroding at other times. sand in that it would kill any reef-dwelling animals, These fluctuations are most. pronounced between the producers of calccareous sand in the area ol t 31VId lip CA rn M, rnl Al x M, 0 J;K Ti u aivid OD CD CD ....... ....... .......... CL .... .... .. 6 -1 ..... .. IF llill po CD CD CID CD Ch CD, Ov fn Od fq rn poll @.c I 17 31VId 91 FU 7.,T" 7!1 Zq 49 CA tj 710 F71 7"n rx T4 rn DIP rn 70 oil r CD 5 31VId 7@ .7 Ih . . 7K P. o r7l OD ISLAND OF KAUAI GENERAL that more than half of the island's shoreline was The island of Kauai is roughly circular in shape, undeveloped at that time. However, the Sitation and has a mean diameter of 26 miles and an area of is gradually changing primarily because of the 555 square miles. It is essentially a volcanic dome, emphasis on development of the tourist industry which has collapsed,in places. Mountainous terrain to enhance the economy, of the island. As such, which comprise the central, part of the island rise open, lands are gradually being developed, for to heights of more than 5,000 feet. The mountain- resort and recreational beach use, mass is fringed by a long, narrow, gently sloping coastal Plain which contains some of the longest. stretches of good beaches in the state. The coastal plain is interrupted on the northwest side by a 16- Table 4 mile reach of which rise from the Shoreline Land Use water's edge, and on the southeast bya narrow ridge Island of Kauai (1962) called the Hoary, Head Mountains which rise to (1962) elevations of about 2,280 feet above mean sea level. Land Use Total Shoreline Sandy Beach Most of the agricultural, commercial,and residential Miles Total Miles Total %of developments on the island. are concentrated along Miles Total Miles Total the coastal plain. The rugged central portion of the Rereational-Pubic ........ 11 0 9.7 5.1 12.4 island will probably remain as timbered or conserva- Recreational-Private .......0.0 0.0 0.0 0.0 tion land. Non Recreational The tidal shoreline of the island is 113.4 miles Development .................. 22.6 19.9 10.8 26.1 long. Eleven miles of shoreline are sea cliffs, higher Undeveloped ..................... 79.8 70.4 25.3 61.5 than 1,000 feet and are physically inaccessible An Total .................................. 11 3A 100.0 41.2 100.0 additional 39 miles are marginally or wholly inac- cessible, leaving about 63 miles of physically acces- Offshore islands excluded sible shoreline. The characteristics of the, island's Source: "Hawaii's Shoreline. prepared by the state of shoreline are summarized in table 3 and ares shown Hawaii Department of Planning and Economic Develop on plate 6. ment in 1965. Table 3 Shoreline Characteristics Island of, Kauai (1962) SHORELINE OWNERSHIP Table 5 shows that Private landholdings com- Characteristics Miles Percent prised the largest- percentage of Kauai's shoreline in-1962, and that public (non-Federal) intersts own Rock .................................... 59.4 52.4 Gravel ........................ .................. .1.2 1.1 the second largest percentage of the - island's Sand .......................................I..... 49.6 43.7 Shoreline. The land ownership pattern reflected Ill Mud (Sih and Clay) ........ ............. 0.0 0.0 table 5 and shown on plate 8 is expected to-remain 2.8 Artificial stuctures .................. .... 3.2 relatively static. Total .......................................... 113.4 100.0 PHYSICAL CHARACTERISTICS AND HISTORY Offshore islands excluded. OF-SHORELINE *Includes 8.4 miles of seasonal sand beaches where the Table 6 describes the physical chacteristics, own- predominant beach material is sand for only a part of the year. ership, use, and condition of the principal sandy beaches of Kauai.The following discussion supple- Source:"Hawaii's Shoreline, prepared by the State of ments the data in the table by providing. general Hawaii Department of Planning and Economic Develop- ment in 1965. descriptions of the physical characteristics of the shoreline of. Kauai, and qualitative assessments' of shoreline conditions. For this discussion, the island SHORELINE USE was divided into, six sections. Use of land abutting the shoreline is shown: on Southeast Shore (plate 9). This coastal reach ex- plate 7 and summarized in table which shows tends from Hanamaulu Bay to Makahuena Point. 15 Which fronts a rcsort hotel, has a vcry gentle slope Table 5 and a low berm which Is (A en cusped. Thc sand is Shoreline Land Ownership highly calcareous and consists of medum-sized grains. Island of Kauai' Congress has authorized the U.S. Army Corps of (1962) Engineers to construct a small boat harbor within Total Shoreline Sandy Beach Nawillwili Bay between the revetted fill area at the %of %of northwest end of the cornmercial navigation harbor Owner and the mouth of Huleia Stream. The harbor im- Mika Total Miles Total Federal. ......... 10.2 9.0 3.3 8.1 provement cosists of construction of an entrance Public (non-Federal) .......... 45.3 40:0 16.4 39.8 channel, dike, and mole to provide a useable area of Private ........... ................... 57.9 51.0 21.5 52.1 15 acres and accommodations for 200 boats. No date has been set for construction of this harbor. Total .................................. 113.4 100.0 41.2 100.0 The Haupu coast, which extends from Cartel- Point Offshore islands excluded. to about four miles southwest of Kawelikoa, is char Source:"Hawaii's Shoreline. prepared by the State of acterized by high and rugged sea cliffs. The south- west end Of this coast is called Kipu Kai and is Hawaii's Department of Planning and Economic Develop- characterized by three excellent sandy beaches which ment in 1965. average about 100 feet in width. The relatively straight northern beach is separated from the middle It is characterized by stretches of low, cliffs of igneous beach by a rocky ridge with boulders at its seaward lava basalt which are interrupted by short reaches of end. The crescent-shaped middle beach is backed by sandv beaches or by artificial structures. active duties 20 to 30 fect high, and is separated The shoreline from Hanamaulu Bay to Carter Point from the southernmost beach,by a pair, of small rocky South of Nawiliwli Bav is mainly sea cliffs 20 to 40 ridges. The one-fourth mile long Southernth-most beach, feet high, except at (lie two bays. A 1,500-foot-long, the longest of the three beaches, is backed by stable 35-foot wide rivermouth barrier beach fronts a duties 50 to 60 feet high. A narrow but shallow reef County park at the head of Hanamaulu Bay. This Fronts part of the northernmost beach, and other ir- arcuate beach is relative stable and has a low regular reef areas are present along this coast (plate 10); however, the water is generally 60 or more feet slope with no prominent berms. The sand is fine- grained and primarily calcareous in composition. deep within a half mile of the Haupu shoreline. Hanamaulu River enters the bay at the south end From Kawelikoa Point to Makahuiena Point, the of the beach. Sediment discharged from the river shoreline cosists Of a series of rocky Points between which are beaches backed by,active dunes (figure. 1). contaminates the water and discourages swimming at the beach park. The bottom of Hanamaulu Bay These dunes extend about three-fourths of a mile consists of fine sand and silt which are among the inland. finest-grained sediments on Kauai. South Shore (plate),The 15.5-mile-long south Like Hanamaulu- Bay, the bottom of Nawiliwili shore -extends from,Makahuena Point to Makaweli Landing. Much of the -shoreline along this reach con- Bav consists of fin sa d and silt. Completion of a comercial navigation harbor in 1932 altered the sists of outcrops of lava basalt or calcareous sand- natural shoreline of the bay through construction stone. The several beaches scattered between the rockv of a break water on the south side, and bulkhead, shoreline are both short and narrow, and some of pier facilities, and a revetted fill area which re- them are seasonal, that is, the sand erodes away claimed about 48 acres of land on the north side of during the winter months and returns during the the bay. The shoreline was further altered in 1956 summer. through construction of another revetted fill area for The 4,000-foot-long Poipu Beachb at the east end deposition of dredged spoil frorn the harbor en- of this reach fronts a rapidly developing resort area. largement project. This fill area reclaimed about 22 This reach consists of several arcuate beaches. be- acres of land. tween rocky points along- the coast. The beaches are Prior to construction of the harbor, it barrier beach between 60 and -10 feet wide and are often moder- ately steep with no noticeable berms (figure 2). The existed at the mouth of Huleia Stream on the west side of the bay. Harbor construction reduced this sand consists of fine calcaerous grains with only minor beach to 300ft long. 50 foot-wide reach of cal- amounts of detritus. A reef fringes the shoreline and careous sand. provides it calm. relatively sheltered swimming area Kalapaki Beach. a 1,700-foot- long. 75-foot-wide The reach from poipu Beach to Hanapepe Bay is arcuate pocket beach at the north end of Nawili- primarily sca cliffs of outcropping lav basalt, except wili Bay. iw bound by cliffs on the east and by the for the reaches fronting Lawai, Wahiawa and Hana- revetted fill area for the harbor on the west. The Beach, pepe Bays which are drowned river-valley mouths. A 16 LT T. ?7 :@.q 7T r y z E5 . . . . . . . . . . .. 1XXXXXXXXXX X, x x x x x X @11X x X x X x. X >1 x x x cc S F5 3, 0 10. A! N 41 4" 44 As Tig. 1 Makahuene Point, Kauai (Camera Hawaii Photo) 18 boat launching ramp at Koloa and a boat harbor at Kukuiula ate the onlv artificial structures within this 'reach. Sandy beache@ exist at the head of Lawai and Wahiawa Bay@. A half-mile-long riverrhouth bar- rier beach which existed at the head of Hanapepe Ba y has been critically eroded. In 1962, this arcuate &I sand beach had an average width of 70 feet. Since that time the beach has undergone Continual erosion, and is presently completely denuded except for a 30 foot-wide bar which partially blocks the mouth of the 1-lanapepe River. The, sand along. this beach is pre- dominantly medium-wsized grains of volcanic detritus n@ deposited by the river. The severity of the erosion M;@ problem resulted in a request from the State of Ha- participation in a beach erosion con- waii for Federal trol pro*ect. Plans and specifications for such a I project have been completed by the Corps of En- gineers, however, construction of the pro*ect has not i been initiated. The east side of Hanapepe Bay has been altered by construction of the Port Allen Commercial Naviga- tion Harbor in 1935 and the Port Allen Recreational Fig. 2 One of several beach bs at Poipu, Kauai Small Boat Harbor in 1962. Artificial structures in- clude a 1,200-foot-long rubbleniound break,,vater, a from steel) in Winter to 'rnod,6-ately steep during the 600-foot-long pier, a 1,000-foot-long revetted mole, suninicr. The water IS LJSUAI@' muddy due to alluvial and rubblernound revetments along the existing sediments from the Waimea River. shoreline.. The shoreline extending about 3,000 feet west Of The shoreline from the west end of Hanapepe Bay Waimea River has eroded continually' since the early to Makawell Landing is primarily rocky outcrops of 1900's. The.erosion became a critical problem when it lava basalt, with a fex-,- short -sandy 'beaches along endangered, beachfront properties. and threatened the some of the inlets within this reach. road parallel to the beach to *the extent that it was S.outhwest Shore (plates 9 and 11). This.18-rnile . rel-ocated further inland three' times between 1940 reach which extends from Makawcli Landing to Poli- and 1955. After the last *relocation, emergency riprap hale is distinguished by long stretches of beach and protection was placed along the eroding bank. The the only extensive coastal plain on the island. The severity of the erosion problem resulted in a request coastal plain is more than two miles wide in the cen- for Federal assistance in a. shor Ie protection pro' ject. ter of this reach, and tapers to the north and south- In 1958, Congress authorizied, the use of Federal east. Except for tbetowns of Waimea and Kekaha and ftiricls'to pay for one-half the cost of a 1,240-foot- a military airfield, this reach is undeveloped. would beconstruCLed Nlahinauli Beach is a 1,400-foot-long, 70-foot-wide by the State of Hawaii to protect Public' shores beach composed of poorly sorted medium grains fronting Waimea town.1 To date, no work on this which contain a high percentage of volcanic detritus. project has been initiated. The beach is bound on the south by the Makaweli Artificial structures of thc Kikiaola Small Boat jetty and on the north by a point of land composed Harbor have altered the natural shoreline wcS1 of of rock and Sand. It is protected from excessive wave Waimea Beach. These StIlAclurcs include it 600-fool- action by a reef'approximately 700 feet offshore. ' long I-Libblemound wcst bmakwater, a 1, 1704ool-lonq @A 7,000-foot-long, 100-foot-Wide beach extends rUbblemound east breakwaier, a concrete .1aipiching A,Vest from Waimea' River to the Kikiaola Small Boat ramp, and a 200-foot-long.groiti. Harbor. This beach, which fronts the town of Waimea, Kekaha Beach, which is 'about 17,000 feet long and is predominantly composed of grains of volcanic sand averages about 150 feet wi&-extends froin the small deposited by the Waimea River. The percentage of boat harbor to the Naval'reservation at Barking Sands. volcanic components decreases along the western end Sand along this reach is about 70 percent calcareous of',.1his beach. This decrease is attributed to a west- and 80 percent,volcanic detritus in composition. Crit- ward-flo@%-Ing alongshore current which moves. the ical erosion has Occurred along a 4,700-foot reach sand along the beach and dilutes the volcanic @com- fronting the public beach park. In 1936, the shoreline portent bv the addition of calcareous grains frorn. the near the ivestern end of the park was 100 feet sea- Shallow wat('r Offshore. The foreshore slope varies ward of the present. highway. and that near the. eastern 19 end was 200 feet seaward of the highway. Erosion. feet and is backed by -extensive sand, deposits. The over the years moved the shoreline right up to the sand is primarily white calcareous fragments with a highway, and necessitated dumping of rock on several small percentage of -volcanic detritu-s. North of this occasions since 1958. to protect the highway re- sandy beach, a 3.5-mile reach of beachrock backed by, vetment. Comparison of a survey made in 1966 with a storm beach extends'-to Nohili Point (figure 3). one made in 1936 showed that. erosion was most. The beachrock along the south end of this. reach is 01 significant at the east end of the park. The comparison exceptionally massive. also showed that an average width of 110 feet Polihale Beach, a 20,000-foot-long, 300-foot-wide eroded over a 3,200-foot reach. This is equivalent beach, lies north of Nohili Point. The beach along to a total loss of 352,000 cubic yards of sand during this reach is more than 20 feet in depth, and is the 30-year period, which is an average annual loss of backed by 50-foot-high sand dunes. Extensive out- 11,700 cubic yards. The 'severity of the erosion prob- crops of beachrock exist at sea.level. lem led to a request from the State of Hawaii for Northwest Shore (plate .11). The Na Pall Coast, Federal participation in a beach erosion control proj- a 14.5-mile-long shoreline between Polihale and Kai- ect. How-ever, investigation of the problem disclosed liu Point, is characterized by precip sea cliffs , itous that Federal assistance in the construction of a which are among the highest and most scenic in the permanent revetment to protect the highway could state. Except for two state beach parks, this physically not be provided because of the high cost of the pro- inaccessible reach is undeveloped. posed revetment compared to the economic savings The hinterland of this shoreline consists of lava ba- which would result from reducing erosion along this salt flows and,dikes of the Waimea Canyon volcanic reach. However, the Corps of Engineers stated in their series which have been Cut into deep valleys by report that continued dumping of rock by local gov- stream erosion, The ends of the interstreani ridges ernment agencies, on an as-required basis would re- have been cut into the spectacular cliffs by marine tard erosion and @ provide some protection for the erosion. Between Polihale and Milolli. the faceted beach. cliff-ends of the ridges are- fairly straight and -about From Kekaha Beach, Barking Sands Beach extends 1,250 feet high. Beyond IN1110111, the cliffs are higher northwest around Kokole Point, a cuspate foreland, but are more irregular because of broader valleys. At - to the Barking Sands Naval Airstrip. This 14,000- a few places the cliffs Tise to about the' 3,000-foot- foot-long beach ranges in. width from 100 to 200 elevation within one mil'e,o'f show. g., ng qg sm M g o"M g -N R@ ,Z M _X"_8 . ..... VNMAM, HL .. .. ....... "R Ir Fig. 3 BarkingSands area, Kauai. 90 The Na Pali shoreline is primarily. lava bedrock, Beaches along this shore also experience changes re- but there are boulder beaches -and small seasonal stilting from severe flooding of the rivers as well @:sand beaches at the, foot of some of the, cliffs, at as from changes in river courses. Except for a some of the small inlets along this coast_ and es- resort area at Hanalei Bay and a military reserva- pecially at the mouths of some streams. Small san'd tion at Kilauea Point, developments along the north beaches at Honopu Valley, at the bay one-third mile. Shore consist of scattered rural residential and agri-, east of the valley and at the south. end of the long cultural areas. Much of this shore is undeveloped. sand beach at i@Llalau are presenf throu out -the About two-thirds of the north shore is fringed by gh year. shallow reefs. The reef flats west of Kalihlwai are as North Shore (plate 11.). This 18-mile 'shore extends much as 1,600 feet wide, but are about half this width from Kailiu Point (figure 4) to Moloaa Bay, and is along the southeast end of this coast. Farther off- characterized by. alternating stretches of sand and' shore, a very broad submarine. ridge extends north- bedrock, small. bays which are drowned river. valleys, eastward from Kauai into *deep water. and lengthy stretches of' shallow fringing reefs off- Keei Beach west of Haena Bay is 500 feet long and shore. Most of the beaches along the north shore 35 feet wide. The.beach is composed primaril of cal- Y undergo significant seasonal @ changes, primarily as*a., careous fragments with beachrock exposed a.t sea result of erosion by winter northern sea swells. level in a few locations. . . ... . ....... z 4 .. .... .. .... ..... .... . v 4; 1--- 01. 4 V rm 011 Z., 7 Fig. 4Kailiu Point and Hanalei Bay area, Kauai (Camera Hawaii Photo) 21 The 1,300-foot-long arcuate beach at Haena Bay harbor at this site have' been.prepared by the Corps is about 200 feet wide in the center section@ but of Engineers, construction of the project has n6t been narrows to the west where it terminates at a mound initiated. The proposed'small boat harbor would alter of boulders behind a coral reef. Low vegetated dunes the shoreline by construction of a 380-foot-long jetty lie back of the beach which is composed primarily of and dredging of an entrance channel and berthing calcareous sand. The foreshore at the beach park in basin in the peninsula between the bayshore and the the center of the bayshore. is very steep because it rivet estuary. receives no protectionfrorn the fringing reef that lies The shoreline extending eastward from Hanalei to off the sides of the bay. Kilauea is a sea cliff which -ranges in height from 100 Kepuhi Beach is a 4,500-foot-long beach on the to 200 feet. West of Anini Stream, a few small beaches broad point between Haena Point and Wainiha Bay. exist in front of the cliff. The beach at Anini Stream The beach averages 75 feet in width except for an area and beaches eastward ate-longer and wider. along the west end which- is about 150 feet wide. Kalihiwai Bay, a drowned river valley, has a 1,500- The beach sand is highly calcareous in composition. foot-long, 100-foot-wide rivermouth barrier beach. Although a shallow reef flat-provides some protection, This seasonally varying beach is generally narrower at the beach was seriously eroded in February 1963. the east. end where it abuts a boulder beach at the However, most of the sand returned to the beach by base of a cliff that forms the east side of the bay. August of the same year. Although erosion continues The beach has a low slope with, at least one berm. at this beach, it is considered to be non-critical at Beach sand is medium-to-coarse grained, and is lire- this tir@e. dominantly detrital material deposited by the river. The 1,300-foot-long barrier beach at Wainiha Bay Kauapea Beach, a 3,000-foot- long, 75-fo6t-wide has an average width of 150, feet. It is about 200 sandy beach between Kalihiwai Bay and Kilauea Point feet wide at the west end where it joins a physically is the last long sandy beach along the north shore. inaccessible reach of low cliffs, and is about 100 This beach is only marginal,ly accessible as it fronts feet wide at the east end. The beach has 'a fairly on rugged, undeveloped land. The remaining reach steep slope and is composed of both volcanic detritus from Kilauea Point to Mol 'oaa Bay consists of about deposited by the Wainiha River and calcareous half beach and half sea. cliffs which i-ise 20 to 200 material from the adjacent sea floor. feet high. The cliffs are highest near Kilauea and Mo- loaa Streams. Most of this reach fronts on Lindevelm Lumahai Beach, cast of the mouth of Lumahai River, is about 4,000 feet long. The width of the beach oped land and is only marginally accessible. varies seasonally, but is about 200 feet wide on the A slightly, arcuate, 2,000-foot-long, 175-foot-wide average. During the win .ter, sand usually moves from rivermouth barrier beach exists at Moloaa Bay. The the west to the east. Surveys made by the University foreshore has a low slope which is broken in places by of Hawaii showed that in August 1962 the west end outcrops of beachrock..; Beach. sand'is predominantly of the beach was 350 feet wide, but in February 1963, calcareous with only small quantities of sand-sized it was denuded and waves were eroding the low dunes detritus. Low dunes behind the beach are vegetated behind the beach. During this same period, the east with grass and ironwood trees. A long outcropping of. end of the beach accreted from 160 to -435 Jeet. The beachrock exists in.,the surf zone, but,the bottom sea- beach generally has a steep fo .reshore because of the -ward of this outcropping, is predominantly sand. absence of a protective reef. Northeast Shore (plate 11.).- The northern half of Hanalei Bay, the largest bay on Kauai, is a half this coastal reach extend Omni Moloaa Bay to Kealia, circle which opens to the north. Detritus deposits at and is characterized by -low sea cliffs fringed by slial- the mouths of the Hanalei, Waioli, and Waipa Rivers low reefs, with a few bays which are drowned river- which empty into the bay, and calcareous sands from valley mouths. In cliff height and embayment the offshore organisms have been reworked by the waves shoreline closely resembles the southeast shore. Ex- into a 2-mile-long beach. The beach has a gently cept for the river valleys, coastal lowlands along sloping foreshore, and an average width of 125 feet, this reach are scarce and physical accessibility to the although seasonal changes occur. Some erosion has shoreline is,marginal. Other than two small beach7 occurred along the west Hanalei Beach which extends@. front residential areas and a public beach park in the. from iMakahoa Point to Waioli Beach Park near the Anahola Bay area, the shoreline along this reach is center of the bay shore. However, the'problem is not essentially undeveloped. The southern half of the considered serious at this tirne. The beach extending northeast shore extends from Kealia' to Hafiamaulu from the,park to the east end of the bay is relatively Bay, and is generally low with heavy resort develop- stable. ment around Wailua Bay. Rivers along this reach The on1v artificial structure along the north shore is empty into gentle scallops of the coast rather than into a 3007foot-long pier about 600 feet South of the mouth. deeper bays. of the Hanalei River. Although plans for a small boat The 6.600-foot-long Anahola Beach has -an average 22 m ............... . A I I W1 I % gsV tS" @7 @w. a". 7 Nt, A A Fig. 5 Ana'hola Beach, Kauai (Camera Hawaii, Photo) width of 150 feet. This slightly arcuate beach is from it cane-hauling road, and tile milln highway. Tlw 170 to 220 feet wide near. the celnter,and narrows to remnants of a small sand-milling Operation mv located about 100 feet at both ends ji gure 5)., The beach has at the north end of tile bea'ch..'.. a@ low' slope and at least one berm. Beach sand'is Kapaa Be Iach extends ft oil it itbout 2,000 feet north predominantly calcareous and of medium-grain size. of Molkeha Stream to Waikc'-a Stream and [ronts it The offshore is essentially sand, and low sand dunes public beach park. The- beach averages about 25 lie behind part of the beach. The beach is subject feet in width and consist's of .fitic to medium grains to seasonal accretion and, erosion, And to changes 1. re- of calcareous sand. It is fringed .by a coral reef ranging st'ilting from lateral shifts in the mouth of the peren- from 400 to 1,500 feef ini@widtll.' Artificial structures nial-Anah.ola Streani.-During the 16-month study of along this reach inchide 'et-tics at the triouth of the Hawaiian beaches conducted bv the LTlli%.el-sitv Of Ha,xall, the pOs!'(1 .oil 01 the streani mouth changvd h%. IWO Sli'(1111115 and it 900-foot-long rubblernound revet- it boul t 500 feet. illent at tht. north cnd of (ho pat k. This reveinicnt was KV4'alia. Beach is al'2,500-foot-long. and @150400t-widc (0111picit-d by the Sl@llc of. Hawaii 111:196.1 to prot(It"t beach II)etween. a iock\ point. oil tile south and a, Ihc S11401-clim, froul closion whi-ch had beell: o(curring sill"111 (,tt\ 611: dic @110*1-111:. Kapaa. StRIZ1.111 ''CI-OSSCS: Ow '@ilwt' 19159. Sill\c-'s Inadc In- lille 19:')9.and jantlar\ I j . , . . , 1 1. .. 'j, South end A thi@:beacll Which @ollsi.Sk of liigil,]\ 1963 shol\.cd that an @Ivcragc of -10 [61 of heach (@dcareous sand. Behind tlie@ beach in-c 101V (ILHICS, ',\@O !OSI along a 1,000-fool-Jol-Ig rc;idl. ThC 23 Which was contined to this one reach of the beach area as result of a severe flood By August of that was attributed to dredging of th offshore coral year a narrow beach zone with a n erosional scarp reef in 1959. Prior to this time, annaul changes and a narrow foreshore. at the beach were small, and sand was usually trans- area of the beach is mainly sand with a few lava ported shoreward along reef channels, then toward Outcrops at each end. the strearn outlets, and out to sea from here the cycle The 2-mile-long sandy reach south of Wailtia Bay was repeated. However, the dredged area severed the fronts a public golf course and open land. The beach reef channels so that sand became trapped in the. averages 75 feet in width and consists of calcareous dredged area, thereby preventing natural nourishment limestone sand. Significant- erosion has occurred of the beach. Construction of the revetment has along this reach. In some areas, as much as 30-foot- prevented further loss of beachfront property along widths of shoreline have been lost. this 900-foot reach. A 2,500-foot-long,100-foot-wide rivermouth barrier beach exists at Wailua Bay. The north end-of this SUMMARY slightly arcuate beach is more stable than the south Approximately 5.O of 113.4 miles of shoreline around end which terminates at the mouth of the Wailua the island of Kauai have been critically eroded; about River and,which is subject to erosion resulting from 15.1 miles have a history of erosion but the prob- flooding of the river. In. April,1963 the beach along lem is not critical at thistime; and the remaining the south end eroded to the vegetated backshore 93.3 miles have a history of stability or accretion. 24 9 livid Let rn 11V .1 U. LA > tj o0% f A' z hill, LA lo 4,@' NIL C To if All, CA 0"' r - . :. = , " I, - rn r 11" LA M# z ILA 0 JI" moll, is 7: is M. CA X, Iss v M 11 0 All 4 o NO. VK fit 9Z L 31VId a z zz ri. m ....... . . . . . 0 )> m > -0 r) J K;v 0 0 Z > z z > > 1011 1A w "j'l 'f 49 Nil rn t4)\f' V1, 1h, k\k 4 1 J\ Jill' hi '0\ z,;r atv \4F IL XI 0 M ; > z c > CA 8 31VId oil ;a C M 0 < r z V% 0 Z 0 0 < 70 Z m z M 3b Po AQ, Jt ic I o .......... 6 07'! o o., O.o:v 3E 3w z 30 3w P. S. C z r 30 6 0401d C, a > saws @ONR)Qm z Iww 310x* CA ml > -410 0 m n .R > M r- 3d3dVNVH 00r) 0 z M.Z -n @l 71. '00 v-0: N 0, -Z z F-) C) 0 0 6 > z r" C@, M-noj z Z . > .... 0 m .. LA 0 z AVS IVMVI viriiiinji 0, Tm i NOW. 0- '@N AVS (A rn, 0 0', :p Sz -1 m m M, (A z AV% f)InVWVNVH 6Z OL 31VId ENA Esi m m A, 0 cy > > j rn IE > rn Z Oki M > 0 rm m OA ul so- 'Al V A- z o co .. .......... ... . ... . A 1: MR. wz z z V, Z'4, A r4o LEGEND Y. @A, P, KAPAA SAND AILU GRAVEL A 0 MUD (Silt & Clay) EM] ROCK 0 1 2 3 4 i L E S ARTIFICIAL STRUCTURES SHORELINE EROSION AREAS CRITICAL EROSION ISLAND OF KAUAI OF N x 1000 FT. (NORTHERN HALF) OF SHORELINE. NOWCMTIC.@L EROSION OF N x 1000 FT. OF SHORELINE ISLAND OF OAHU GENERAL Table 8 The island of Oahu has an area of 604 square Shoreline Land Use miles. It is characterized by two parallel mountain Island of Oahu ranges, the Waianae Range on the west and the Koo- (1962) lau Range on the east, fringing a fertile plateau. The Total Shoreline Sandv Beach tidal shoreline of the island is 198.5 miles long.The characteristics of this shoreline are summarized in % of %of table 7, and are shown on plate 12. Detailed descrip- Use Miles Total Miles Total Recreational -Public ................. .. 32.1 16.2 10.7 21.3 tions are included in the paragraph on the physical Recreational-Private................. 15 2.3 2.5 5.0 charcteistics and history of Oahu's shoreline. Non-Recreational Development................... 110.5 55.7 19.9 39.5 Undeveloped ................... 51.1 25.8 17.2 34.2 Table 7 Shoreline Characteristics Total .................................198.5 100.0 50.3 100.0 Island of Oahu' (1962) Off shore islands excluded,except Sand Island, Ford Island, Magic Island, and proposed reclamation of reef lands in Keehi Lagoon. Characteristics Miles Percent Source: "Hawaii's Shoreline" prepared by the State of Rock .... ................................ 70.2 35.4 Hawaii Department of Planning and Economic Develop- Gravel ......................................... 8.1 4.1 ment in 1965. Sand ..................... .......................55.9* 28.1 Mud (Silt and Clay) ..................... 13.4 6.8 Table 9 Artificial structures ..................... 50.9 25.6 Shoreline Land Ownership Island of Oahu Total ............... .............. ............ 198.5 100.0 Offshore islands excluded, except for Sand Island and Ford Total Shoreline Sandy Beach Island. %Of %of *Includes 5.6 miles of seasonal sand beaches where the pre- dominant beach material is sand for only a part of the year. Owner Miles Total Miles Total Source "Hawaii's Shoreline" prepared by the State of Hawaii Department of Planning and Economic Develop- Federal..............60.9 30.7 10.2 20.3 Public (non-Federal).41.7 21.0 12.3 24.4 ment in 1965. Private..............95.9 48.3 27.8 55.3 Total...............198.5 100.0 50.3 100.0 Offshore islands excluded except Sand Island and Ford SHORELINE USE Island. As shown in table 8 and on plate 13,55.7 percent Source: "Hawaii's Shoreline" prepared by the State of of Oahu's shoreline was in non-recreational develop- Hawaii Department of Planning and Economic Deveop- inent in 1962. Unlike the other islands, where more ment in 1965. than half of the shoreline was undeveloped, only 25 PHYSICAL CHARACTERISTICS AND HISTORY percent of Oahu's shoreline was undeveloped in 1962. OF SHORELINE However, much of this shoreline is expected to be placed in resort and recreational use to meet the Table 10 describes the physical characteristics, increasing recreational needs of residents and visitors ownership, use, and condition of sandy beaches for alike. which data are available. The following paragraphs supplement the data in the table by providing general descriptions of the physical characteristics of the en- SHORELINE OWNERSHIP tire shoreline around Oahu and qualitative assess- The shoreline around the island of Oahu constitutes ments of shoreline conditions. The shoreline descrip- 21.2 percent of the total shoreline in the state, and tion begins at Wawamalu Beach Park and moves in a 27.2 percent of the state's sandy shoreline. Table 9 clockwise direction around the island. and plate 14 show the distribution of ownership of South Shore (plate 15). The south coast of Oahu land abutting Oahu's shoreline. extending from Wawamalu Beach Park to Barbers 31 ?,?,=::F7 X X x 7: Z M Ei- 7 Iz Iz rl: - - - - - - - - - - 8@ 3 x X x X x x x X XXX xx X X X x cr x T T 7 77 wT Oc Ic f- UQ Iz tz lz 5Z 5-. R- 12 @E RE 5 i 2 5 - - - - - - - - - - x x >1 x x x x x x Ew X, X x x x X.X x x x ;01 X It Point is gCIIVVNII@ IOVV, thereby affording relatively E xcc pt I or I la I i,.1 I I I 11; 1BeachVa I.k. I I I eoiI s I I I I) c fro 111 VIISV aCCess to Most parts of the shoreline. The South- I-LI1011.1 Point to Nlaunal6a Bav is in exticnicl\. rockv, ern' exposure and stretches of fringing reefs (plate 16) terraced sea cliff affording.only niaqginal accessibility provide reasonable protection against damaging ef- (figure- 6). 'The 1 800 -foot - lo6g: 30-to 100-loot-xvide fccis of storm waves and tsunamis. The location.of sandy'bcach at Hanauma BaN.- had been eroding to Llonolulu, the largest urban development in the State; the extent that coconut trees about 20 feet. inland the largest civilian and military ports; and a large from the shoreline were' being unclormined (figure 7). rid Cotinity hf 171011011-1111. sharc of the armed forces establishments along this III April 1970, the City a De- coast make it the most important coastal reach in Lh.e partment of Parks and Recreation, initiated remedial s ta te. action for the beach park. The beach erosion control The reach:between Wawamalu Beach Park and Dia- project consisted of construction of it wave '.barrier, mond Head'i.@ characterized by rock), coasts and pro- reston, tion of the beach Jigure 8),...and excavation tective structures with only @ few short reaches of of a new swimming area. sand-N, beach. The shoreline from WawAmalu 'Beach The shoreline of Nlauna.huf Bav has-b6!n (onsider- Park to Halona Point consists'of 1,,500-. to 2,200-foot- ably altered by artificial Structures w,hlch '@i!]ClUde a long reach@s of about 100-foot'-wide sandy beaches boat,.launching ramp, seawalls along,''thc residential between stretches of lava basalt outcrops. The beaches area at' the east end of the bav and.coral flil',whirh are qui(e steep and front an area of low dunes cov- Nvas placed along the center-section dii@ring initial -ed by grass and k I'[We I rees. I -orl -esi mial area development of I nia.riiia chied I I& In 2@ zft er MWIPIM, A All 0 111NIL, ml@,.__- t@4 X Fig. 6 Rocky coastline between Hanaurna Bay (lower left) and Wawamalu Beach Park (upper left), Oahu 34 M. 1, 111c vall(-N belluid the ba@@, (figure 9). Flic cocil till aw:t -is part of' the NIal -it Park, and inaltia Bea( is I i otit,cd 1)), it 1,000- foot- long 10-foot-wide sand beach which is gradually eroding. The offshore'area of the bay is characterized by one of Hawaii's shallowest reef's. ReNtively few organisms appear to be living'on s re f-flat wherc local patches of sand have been 4 T observed. shoreline in the Kuliouou area at the west end of Maunalua Bay is largely. a nludflat Lip to Palko Peninsula, after which it is an almost continuous stretch of seawalls with narrow, poorly sorted gravel and -sand beaches fronting them. Except for two 1,000- foo t- long, 50-foot-wide sand beaches, one of T .whi ch is artificiallv constructed, the seawalls extend to Black Point, a rocky headland formed when lava 7, .from a late eruption floNved sea,ward@across the reef. Fig. 7Undermined coconut tree at Hanauma Bay Beach Park The seawalls at Niu and Wailupe peninsulas within this reach border on ancient Hawaiian fishponds which have been filled and developed into residential areas. . .. I . .. Erosion has occurred along it 3,000- foot- long reach within the Wa la lac -Kah ala residential area which ex- tends from NVailupe Peninsula to Black Point. Erosion in this area has undermined steps, seawalls; and kt@-@@' beachfront prbpert\. Erosion has also occurred along the artificiallv constructed sand beach. fronting a re- sort hotel in the Kahala area. The erosion reduced the recreational usefulness of this beach and neces- sitated periodic beach nourishment which has been accomplished bv private interests (figure 10). From Black Point westward around Diamond Head, stretches of rock\ coast on which are cut. a terrace about five feet above sea level alternate with narro-,v beaches of fine- to i-nedium-sized coral fragments (figure 11). Fig. 8 Restoration ofthe beach at Hanaurna Bay Beach Park, The shoreline from Diamond Head to Pearl Harbor Oahu. marily, aytificial the result of extensiv dredging@ is pri e of reef areas, construction of artificial structures, and filling of former inudflats, fish and duck ponds, and shallow reef areas. These lowlands are the urban areas of the citv of Honolulu and support a concert- trillion of indu@trial and commercial facilities as well as recreational, resort and residential areas. .0 Over 10 million visitations by swimmers, -surfers, sunbathers. and other beach users are estimated ,to have occurred at Waikiki Beach in 1970. It is prob- abIv the most well known surfing beach in the world (figure 12). This two-mile stretch of shoreline ex- tending from the west end of Diamond Head to the Ala Wai Yacht Harbor, was formeriv a barrier beach M;; fronting swarrips and duck ponds. This beach is now almost entireIN artificial with imported sand, groins and seawalls along most of the reach (figure 13.). Alteration of the shoreline resulted primarily frorn attempts to reduce beach erosion which date back to the earl%- 1900's. Since that time, numerous remedial Fig. 9 Maunalua Bay area, Oahu 35 R Rlt@,@@ R@ z, 'M 1,-4.f,,qpg g-14I Nil. 90MG, Ror v, 0 Fig. 10 Kahala Hilton Beach, Oahu (Camera Hawaii Photo) actions have been Indel)(1-ndently pursued by various two-nule-long beach var\- I ii- %`v"Idili frolin Olto 150 fect, Intercsts, including property oNvners, the Cjtv and except at the Ft. DcRussy.irtilitary beach @ii thc 1%7csi Countv of Honolulu, the State of Hav.-ail, and the cn(l. Although this bcacli-i%as micc front 0 1() 150 feet Federal Govvnitnent. Rcinedial iricasures have in- I'vicle, it has. recenll\, bc(@111 improved by Ilic Co,rps of cluded construction of it \arietv of structures such as Engineers. in(] no%%- has ;in avcragc xvidth of' 1-60 fect seaNvalls, cribv,-alls. and rubbleiriound and sandbag above incan loNver low Nv.inci. groins. The effectiveness of these structures vary; The arlificiall\, constructed Duke Kahanainoku lio%vever, the net effect has been rnino 'r,.and erosion Beach adjacent to Ft. DeRussy.co?rnprises 111c western is still a problein at this beach. The severitv of the linut of lValkiki Beach. 0)11@MUCIC(l In 1956, this rec- problem is exernplified by a brief history of Kuhio reational beach consists of' it 1,000-fow-1 'ong, 150-foot- Beach, a 1,500-foot-long reach in the center of Wal- Nvide sandy beach area,-a 7-foo.t-deep,. 150-foot-ivide kiki Beach. Action taken in Mav 1939 to curb ero- offshore sxvinin-ung arca, and it 6-acre lm,oon Sion at this beach resulted in placernent of a 150-foot.- xvard of the heach (figure 15@). The salidv beach is pro- Nvide beach. Hoi%-(-\-(-r, within eight N.ears, a section of tected by tivo groins, one :rt. each end of the beach. the beach ivas completely dentioled. Action taken hN Although some loss of saind ^occurred during the first the Territorv of 1-laivaii in 1951 resulted in, aniong le\\. X-cins 1,011olving completion of the beach, this %vas other things. placeinent of 1 150- foot -N\- Ide beach. ittlibilic(l to [tic of it beach rcsh-,Iping Hoivever, crosion lias continued to occur, so that the to (onfol-111 Nvith t'lic prev:i1ling wave front. ,jU'tcr the beach In width, front 0 to 230 fect reshaping by wave ;Iction. [lie be*,tch stabillicd I() Its Jigure 14). The rem@iltiiiio reaches of this fainous pi-csciiii crcscm simpe. iind s,.ind toss has bcen 11111101'. 36 "Flic Ala Wai Boat Harbor ininictliately ivest of Duke lionolulti Harbor. [lie lill-gcsi cIvIl port III 1-fa%vaii KalianamokLi Beach is the largest and finest light- and tile only coninicivial (Imp-dral't harbor oil 0ahu, draft vessel harbor in the state with it berthing area was originally devc1oped in the' IMC 1700's in it nat- of' about 31 acres and slips for about 515 craft (figure ural protected harbor approxiniatck, 7 miles east of 16). Construction of this harbof in 1935 altered the Pearl Harbor. Roughly crescent shaped, the harbor- natural shoreline by dredging of an entrance- channel is approximately two miles long and varies in width and small basin in the wide, shallow, fringing reef.. from 600 to 2,900 fect. The existing harbor has been Since that time, many improvements have been . extensively expanded from i(s. original configuration made by the State of Hawaii. The existing harbor by dredging of berthing areas-inio the natural shol'e- .Consists of a 1,700-foot-long breakwater, 2 interior line and construction of pier Lind other harbor-relawd moles, I wooden T-Oier and a 200-foot-wide, 1,40.0- StrUCtUrcs along 111c ('11111-c shoreline fronting the har- footriong entrance Channel. hor coniplex. San([ Island, a 500-acre manniadc Island Ala Moana Bea(h Park, .the finest and most pop- which protects the harbor Jroni the open sea, was created oil tile shallow recl' offshore from the harbor ular bc-ach park in urban Honolulu, lies between the b.y deposition of spoil materlid.from dredging opel'a- Alit Wal Boat Harbor and Kewa.lo Basin Light-Draft -s. The topography of the harbor tions over the veai Harbor. The 4,000-foot-long, 150-foot-wide beach at. Ala Moana is primarily artificial. Magic Island at the. complex, including Sand. Island, is relativeiv flat with ground elevations ranging from 0 to 10 feet above sea east end 'of Ala Nloana Park is a manmade penin-, level. sula which was completed in 1964 through recla- ma .tion of about 30 acres of shallow reef (f Iigure 16). The reac h ex te nd Ingfrom 1-1611011,111_1 HarbOl'tO Pearl Harbor is characterized by a military reser%ation and .The martmade light-draA harbor at Kewalo Basin acivillan III&ISIrial al'Ca NVIIICII IIICILIdes tile 1-1011011111.1 was constructed in 1945 by dredging of the coral reef to provide for the berthing basin and entrance this reach is prinimily mudflats and graNcl beaches. channel. The existing harbor is approximately 800. The two sandy beaches this reach an. @Vitllui feet wide, 1,000 feet lon , and 20 feet deep (figure 17). tile military StrUCLUI-Cs IIHC A 9 The entrance channel Lit the southivest corner- of the 2,500-foot reach innncdiatclv@@vcst of' Honolulu I lar- .01 harbor basin'is 200 feet wide. 1,200 fee( long, and bor and a 4,000-f6ot reach fronting the inicniational 20 feet deep. airport complex. 0511 @. .. . ....... X -d .. ........ Fig. 11 Rocky coastline around Diamond Head, Oahu .37, . . . . . . . . . . . Z I Fig. 12 Surfing on Waikiki Beach, Oahu (Camera Hawaii Photo) Most of the shoreline becureen Pearl Harbor and A 7,200- foot-] ong beae-h. fronts the. residential area Barbers Point is in inilitary reservation, which in- ...,.west of Eiva Beath Park. Al-though'itie beach has an cludes a U.S. Air Force base, the U.S. Navy's Pearl average width of 50 feet, it tapers in width to sec- Harbor complex, and its air station at Barbers Point tions where the shoreline consists of swawalls, Erosi.on (plate 15). Much of the shoreline within Pearl Har- which has occurred along a 4,000-fooi-long *section bor has been altered to provide for berthing and ship- is considered significant from the standpoin t. of prop- yard facilities. Other areas within the harbor are erty losses. either muciflats or gravel beaches. Other than the har- Oneula Beach west. of Ewa. Beach is approximately ,bor area, the shoreline consists of alternating 3,000 feet long and 56 feer ivide. Sand on this beach stretches of rock,.,@ and sandy shoreline. Along parts of consists of rnoderatefN: well sorted, medium sized the rocky areas, Sand can be found immediately in- grains of calcareous origin. However, short reaches of land of the water-level beachrock. The primary sandy low ridges of calcareous gravel also o&ur along this beach areas are at Exva Beach, Oneula, and artificially beach which generallN@ has i level backshore which is constructed Nimitz Beach. built to a sharp berni, crest and then to a steep The 400-foot-Jong,, .80-foot-wide, beach at Ewa foreshore. Beach Park consist-, of medium- to coarse-grained, Nitnitz Beach, a military beach,park fronting the poorly sorted, and predominantly :calcareoi-is sand. Barbers Point Naval 'Au- Station, 'is approximately The foresliore IS Usually quite steep and sometimes -1.000 feet long and 50.feet xvide. The beach was arti- SUpportsa berni (if gravel resultull- from stc)rins. Ero- ficiallv constructed -.uid consists of *dium to coarse Sion has occurred at this beach, but is confined to the grains of cal(ar.cous origin. west of the park and is considered rninor. West Shore (plate 15). Flic,2,5-inile-long wach from 38 Barbers Point to Kaena Point is characterized bv a hjnt'(-_@rland of broad, arid vallevs alternating willi Sluelisidud ridgcs; by a shorcline of rocky sirciclics al- wiliat.ing with sm-1clics of cxccllclit bcaclics, and 1)\ an offshore arca ()I very narrow iccfs with a St('ePt')* descent to watcrs ol a few hundred fatlionis than is characteristic of all)- other coast on Oahu. Develop- merit along this shoreline consists of military reserva- tions, homestead lands, and rapidly expanding res- idential and resort areas. This shoreline supports a total of 12 beach parks, two of which are military parks and the remaining 10 of which are public parks. The rocky shoreline consists of either beachrock, outcrops of Walanae basalt bedrock or raised coral reefs@xvhich have created terraces 5 to 10 feet above sea level. Beaches In this area are from about 1,000 to 5,06.0 feet long- about 100 feet, wide, and are generally composed.of medium to fine grains of cal- Fig. 14 Eroded conditions of the Kuhio Beach sector of Wai- careous material. Except -for the beach at Pokal Bay, kiki Beach which is protected by. a breakwater, the beaches ill All M 4 g Vl',' Z- !k AM MA !w-4q Fig. 13 Aerial view of Waikiki Beach .39 1111's @llca lwvc sl( d S(.;Isoll;il hangt.s. and dillic ridgcs. s A bal-c harl)(w licar liarbcls lloi:lit, ;I bicA%vaiej iind lal-litching ranip ill Pokai Bay, and ;i f xv short stretches of seawalls are 'the on1v art 'fi( 'ill SLI-LiCtIffeS T", along this shoreline. Privatch-' developed. tli@@ Barbers Point barge harbor scrv-es a 1,300-acic industrial (Olnplex inirnedialich- west of the Barbers Point Na%al A Station. The harbor ivas conipleted 'it 19611 by ex- li I (avating and dredging afl I @shaped area on die flat coral coastal plain. Ditnerislons of t,he basin arc ap- -ox -ince channel, pi Irriatcly 520 hv 700 feet. The enti, inClUding the offs I to re por nioi i, is 1,300 feet long and 220 feet i6de. Additional alteration of the shoreline -oin con- adjacerit to the barge harbor would result It struction of the proposed Rarbers P.oini Dcup-Draft Fig. 15 Man-made Duke Kahanamoku Beach Harbor which was auflior]-7ed by the C:ongrcss under the River and Harbor Act.' of 1.965. Engineering plans for the harbor are being dcvelopcd b\ 1.11c "'W"4 I AN11 -'s ps of EllginCCI S. Col -o, 7; Exccpt for signih(ant' ct ,[()it it lit(, ptibli( )ark ;it Nlaili Beach and Ow ntilitai.\ park ;it 11(kii Bay, Ihc rcach hci%\c(,n Rifltcrs Poki;i and -Kacila Point Is charactcrized I)\ seas()l 11 cros,oll and a(, rction. The crosioll %vilich o(( li-rred a4()ng a 2,000-T0()t-long reach of Nlaili Beach Pa.rk durliig- dic NvInt(i of 1968-fi9 tindermincd an otlidt)or slio@vci Lit i1ft.-\ and .1vopard- l/cd ill(- stabilli\ ()I the park's (()mforl st.1tiOn. This X\-,Is ill(. Illost sc\cl(, .1-11(.1dunt ()! 11.1c which has hccll o(k (it nng it 1111 s h Is [lie coCl a 6011 1 inc @vh idl. has lVL'CdCd J boill fCCl 'd1lrillg 111c last "0 \.(;ars. F.rosion along Vilc ccll:Wl Sectioll of,l,1lc,1jeaCl!l flont- 4,119 ill(, 11104tary beach. park at Pokai 'Bay lias qndcr- nillied a -retall-I'llig Nval] and clidailgercd several ad- Fig. 16 Aerial view of Ala Wai Boat Harbor and Magic Island, jacent strUctures. --Fllis (.!rosloll, %vilich. is redti(jilg tilt. Oahu recreational 'Usefulliess'.01 ;the. -beach, - Us mIll(ill(-xi to th.,c center. section: -j he morthern. SC(Jip1l, is relatively sttble and dic soutlicni section is ac(i,cuing. Rcinci-lial ilt,11011 Was Ulkcll on st-veral oct.asiolls I)v Al-111N, Rcscrvc -titylts ivho tratisferl-t-d Sollic of.01t. salld fropi the accrctcd soudicill scetion to dic'(1011ldcd (t.111cl. section of the bcach. North:Shore (plaw 1,7). "This 21-in-ilc-lon,, rcidi ex- lClids froiiiXaena:Poiiii to,eKalittkii. Ilic inain,coastal features of@lllis-rcldi aic llic sil:ollg williel stirl and the irregular rect. S(orlli origi_ 11-11v ill tile of tht--Aletitian-lsl@lnds C ftell CAUSC cxlrellic sill-f conditions 101.101, in H ict -sc\cre ifaluage to flic bcadles and beaclifrolit propt--i'lliCs.along tills coastd reach. 11icse stornis tisti-AlY,occur (juring tile wilitcl. IllolilLIS. 11lill-ill" (hc slitillner. Ihc beaclic's usliall\ accrvle. ind-in, anlol'it- the Nvldcst and hest bt-adics oil (11c Isklind. Except lot. "I llillital-N. all' lidd and I.-mrk, most of tills n:a(l) is, ill 'a-riciliture, icci-cational beach paiks, @md rcsidentiA develOp- Fig. 17 Aerial view of Kewalo Harbor. Oahu 40 The .3-mile-long sliqrclille initnedlateIN. east of Ihe Ko()I;Ill illid NV;J;tll;lc' RAll"(1s. I Ills aw;l comilills ka,lla Point is it plalf'orin (III into ]a%iI basalf lical. :1 L11-ge sil."4al. plalli'llioll '111d III(. folill"'llous sillall. cxl@tlng sea level. Generally, this reach is covered t9wils of Wmaluit alld I lalcl with boulders and cobbles, but there are several The shoreline along this 11;ls tw(j bays and al- stretches of sand beaches and a few tiny pocket terna(ing reaches of' sandy bcit( lics and rock outcrops. beaches..This reach is followed by a 6-mile-long reach The only significant ah(:ratlon ot the ii'mirai shoie- known as Mokulela Beach. The shoreline along this line along [Ills reach is at the I-I'llellva Bo@l[ I-I'llhor ri'lach is predominantly sandy beach with a few scat- at the wcsi.cnd 01' Widilkli 'I B;t\- jigure 18). As dirccied tcrcd al"Cas of exposed 6eachrock behind-which, are by the Ullil.Cd StittCS Congress, (fie G)Ips of I'M- found pockets of sand. There are extensive dune gluCCUS ('0111I)ICIC(I IIR' F'Cdclill pol-tioll of 111c halhol. Vidgcs along tills rcach. Some of the dune sand has in 1966. This poilloll of, a 610-lool-Iong, been excavated lot' Cominercial I)Urposes. Nlost of the 120-foot-1%.'Ide, 12-fool-decp clill-all(c chitilliel; , a dunes are SLable. but some at the west end are 1,"'00-foot-long revel'Icd @ niolv; it )20-fooi-longl active. Critical erosion has occurred along a 2-mile 80-foot-wide diversion channe.1 for the Analitill-i River; reach of Mokuleia Beach. This reach was also severe- and -I 7.4-acre protected harbor area. The State Iy damaged during the storm of December 1-4, 1969. portion of the harbor was completed in 1967, and l4igh waves damaged structures and inundated prop- consisted of dredging of it burthing arca: constru( lion erty as far as 250 feet inland from the shoreline. of 20 cativalks to accommodalc 10 boats iind a niar- The hinterland of the reach extending from Nlo- ginal whalfadjaccill tothcJ@illluhillg raInp: pavingof, kuleia Beach to Haleiwa Beach Park- is a gentle [Tic area behind uhc.cdtwalk.@ @wd margiiial whiji-f: and coastal plain vdilch slopes inland to it saddle between instillIallon of, litillm". Mm 1*71:1 2. MOr `@'7` I Opt "vq NNW- ........... Fig. 18 Aerial view of Halelwa Harbor and Haleiwa Beach Park. Oahu, 41 Haleliva Beach Park, which lies immediately east Z of the boat harbor, has experienced critical erosion. lit December 19-19, the entire shoreline from the north of tile 1);nk to lilt, triouth of the AnahLIlu R.iVCI 1 `4 Was front(-(] kv ;fit excellent sand beach which range( III 1".1dill frol'n approxiinalcIN 90 to 130 feet abOxC -*A tllcan lowcl low water. Ilow(WC!" (1111-ing tile cal-IN 1950's ur@i(liml cioslon was observed. 'Fit s crosio Continued, ;fit(] bv December 1965 the beach fronting @J it SC(1JOTl 01 tile park had eroded to within two feet of a seawall xvhich collapsed two months later. Oil March 9. 1957, a large volume of sand was lost due to a tstinanii which originated in the Aleutian . ..... Islands. The severitv of continued erosion of this I -ill participation in a beach ero- beach *ustifled FCLICI T@ slon control project which was completed in 1965, X and I-Cstilicd In. alliong Other things, a 1,600 fooi-long beach with a width varying.frorn 1-10 to 265 feet Fig. 19 Damage to a section otthe coastal highway along Kai- above the mcan lower low watet line (figure 18). wailoa Beach, Oahu However, tills beach. as well its the adjacent small boat harbor. was again severely darnaged during the to about 1965, The beach is I)OW it POIRIlar Public s Orin of December 1969. Sections of protective struc- beach park, although' lurim@ thc winter t S\%:Illlllllll(l, c tures stich its I)reakwaters and groins were darnaged is CMITIIICIN@ dall-IM-01IS be(,ILISC of hillh WaVCS and and al)JAON1111@tICIN 7,000 CLIbI( yaids of sand were strong 1-11) currents In tile I)ily. 10St. AS it lC',UII. Illf@ State 0I IlaWaii rC(ItICStCd Fed- Sunset Beach, a 11vo-Illile-long reach c@ist of Win- Cral Pat li(ijml IM] Ill ClIl(1rgcmy wpair work lot Ilic IlICa B.I\', IS the 10119CSt WhIC I)CM11 OH OJI111. AlthOLIgh bca(Il lmrk and inall hoiit haibor. lit November 1970, OMCI_oI)S Of bCiIL'Iliock and raised rek-1 .11C SGISOnally the Corps ol Frigineer-, (ompletedrepair of the (]am- CXpOSCd ill tile WilICI-1111C, tile '11111d I)Chilhl therri is aged -roln-., mid offshorc bicakwater, iind placement contilItIOLIS all(] AVLTagCS about 200. tcct ]n width. of aboUt 7.000 ( uhl( \ards of ,and over the croded Sc\erc erosion occurs .(hiring ill(' WIMLT, ICSLIltIng Ill sections of the bezich. it steep foreshore. Howevel-, (ILII-Illg tile summer the Kitivalloa Bc.@jdi, -I two-mile reach extending cast foreshore slope is relatively critle. The sand along g this reach is poorl\. Sorted'-IlledlUrn- to coarsC-SiZCLI from Haleliva Bcach Park, consists of alternating stretches of smi(IN beach and outcrops of lava and grains of calcareous origin..'Trosion during the past beachrock. Thc beach is predominantly niechuni two vears has endangered beaclifrolit along grattis of hi,,hIv calcareous sand. It changes season- half of tills reach inid. iS'V0IlSIdCrCd critical. Erc)sion ally and experien(es ill-) to 40 feet of erosion during along flit, remailling 11,11f of this reach 'IS 1101 C0n- the winter. Dill-big tile last few- vears, erosion along sidered to he of sigimilficalit-c at tills t@Hiw. 'Flits re"Ich was also se\ercly daillaged In illc siolln of December a-2,000-fool-long leach has encroa(hcd oil residential propeity to ill(, extent that remedial mcasures are 1 -1, 1969. required. The high wa@es during December 1-4, 1969, A hrozidcr coastal plitin characterized hv hills of old, resulted lit cfonsiderable loss of sand, structural clam- litilificcl sand duties and inarshy lowhinds extends it vs. and lwot ot prolwit\ (figure 19). from Kawela Bay to -Kahtiku. The shoreline along 9 this reach is pi-cdoininailik rocky. In general, points Waimea Bit-.,, %%-lit( li lies eas( of Kawailoa Beach, is flanked bN wide expanses ot jockN shojellne, main- of land along this irl-CgUl ;it* coast are of raised reef IN Lava bilsalt. Ille illost itilport.1111 ot I tile few I iver- limestone between extensix-c developments of beach- mouth barrici bcl-tchc@, (,if Oahu lies at the head of rock. There is consideiablu Sand near the shore, bUt this haN. Thk -.iicuatc pockc( beach is iiboltt except toi- beaches it -ca,r- Kiwela Bay, most of the l 800 fi@vt ]of).- ;Ind 1@50 feet I% idr. Tht. Iviclill of the Sand is Ill ilclivc and SLIhIIIZCd dLtIICS OY ill StOrIll beach varies ;ea@;onilllv. ivith Silild iloIll tile SOLIth- beaches which ill't- beaches CrCJIC(I 11111IR-diatCIV Ill- northeast elid din-flig tilt, 1\1 west end moving to th( land (A rock outcrops by siorm-dcposiiud sand. ter. then moviii,- ba( k during ill(- suninier. Soint, Sand East Shore (plate 17). -1 If(- eastern of, The I)L wilidwa)(1 coa"[ of, 0alill is chara( 1crizcd b\ rclat*vcIv also moves olkhort' (1111 ilhg tile Wilitt'l.' 11;1,' 1 ZI_11tCCp f0I_VsII0I_C dIll'ill' tile AVIIItCI ilild it H:It 011C wl(ic -ccrs ,(f avs. This din-Ing tile sunitner, The sand is AVell-sorled. W.Wil CX1CIIdS 11-0111 KaIlLiku if Nlakapinj Point and -1.1ills of cah-arcous origill. and had collsisl,; of "l-ri(Illfor'd ;If)(] resith-mial du\clopincills, been exiclisk-ck Illiticd lot- C01111lierclal pUrpOSCS Ul) illid sC\CI-.Il IMblit IM11S. 42 Hic norilict.n. third of, [fit- cast'sli(we cmends iroln. . (of' bc;i( hm( k is ('xi)(im-d lit ilic pildillf- ()I (Ili- hr;i( It. KAitikii to Kalac-0io licatir Park, and is chmacterlmd Hicic Is 114) bi-I-11i dckcl()pl1l(-III, bill ;I s;iIjI1%, \('g(.I;I- 11) N@ A IMI'l ( )%Nl coasial I )LIM bel ivccil Ille S(I@l and tilt, cast wd Icl ract. is ill(ll( allvc (J ali ()1d lirl In. I hr Icl I;k( c liank of tilt.- Koolau Range. Dew-lopinei its along this 1.11 bordcr(A on Illc 1:111dwold sidc by ;I vugcuilcd reach are priniarliN agricultural and residential, and old (little ridge oll which hoilses Irc blith. Include six public parks. Although sandy beaches Laie Bay, iniinedlatcl\ S0IIdI of IIIC L111111-1111Cd ]):I\'. front much of this coastal reach, they are all very is convex seaward at tilt, ceniter and hroadlN- omc@tvc narrow except for those at Kahuku and Kahana Bay. seaward oil both sidcs. The beach hits a rcliltivcl, ,, Part 4 the coast, particularly sections at Punaluu and steep foreshore, although it sniall berin O(Cilsti)II1,1111V Kahana Bay, consists of b6ulders and cobbles. Sea- develops. The sand is well sorted, med III) 11-S ited walls 'which are common along parts of this coastal grains of calcareous 01-1.4ill. rcach weic constructed lit an "effort to protect beach- A narrow but altracMi.- bc@i(h 1'ronts it shallow rr:1111.1)ropcrt@v from erosion. tinnarned bay lit tilt- (ciiier of' tlic reach cxicilding A 4,0007l'oot-long reach fronting a golf course@in from Lale to Hatiula. Tlic heach Is sliglltl\@ arctlaw, Kalittkil has an. a\,crage Avidth of' 100 feet and consists with a small rocky point to thc' north and it broad, of, sand and bedrock. The reach extending from Ma- rocky and sandy point to the. SOLItheast. The sand is Uhoa Point south of the golf course to Laniloa Point poorly sorted, medium to coiu-se grains of (alcareotis consists of two ba\ '-s with beaches a\,eraging 70 feet material. The head of a large., steep-wallcd, sand- in xvidth. The first, Ml Unnamed crescent shaped bay, bottomed channel lies close.to shot(, lit ilit: mIddlc is composed of calcareous, moderateiy well sorted, section of the bay. Thc recj' off Ihc solith 1);11.1 (A thc fine grains of sand. Rock is exposed at the shore beach is \-ery @vidc and sliall(MV: near the north.end of the baN:, and it small patch @nwgx"@ g" & a M, 7111", i, -MM N ... . ...... M. 41- . . . . . . . . . . 47,", M j @V to U,@ Fig. 20 Aerial view of Hauula Beach, Oahu 43 The fairly straight but narrow beach fronting the mer of 1969 to alleviate the damage from erosion public park at Hauula is 2,000 feet long and 40 feet during the previous winter. wide(figure 20). There is no berm along this beach The 1,700- foot-long, 40-foot-wide beach at Kaaawa which has a moderately steep foreshore. The sand is Beach Park has been subject to erosion over the years composed of fairly well sorted, medium -sized grains, (figure 21). Since early 1962, from 40 to 60 feet of about four-fifths of wjich are of calcareous material. land has been lost due to erosion along the entire Erosion since 1935 has claimed an average of 14 feet length of the beach. High waves during December of beach along a 1,400-foot reach. In November 1969, 1968 and January 1969 were particularly damaging, the top of the beach slope along the northern end of and caused undermining of numerous coconut trees the park was within 5 feet of an adjoining highway as well as the park's comfort station. In December right-of-way. Toward the southern end of the park, 1968, the City and County of Honolulu Department of the top of the beach slope was within 3 feet of the Parks and Recreation dumped rocks around many park pavilion which houses a concession stand and coconut trees, the comfort station, and along a por- bathhouse. The top of the slope along the central tion of the beach berm as an emergency measure to section extended along a line of 14 ironwood trees retard erosion. Construction of a new pavilion-bath- which have been partially undermined by erosion. house was postponed because of the severity of the The reach from Hauula to Kahana Bay is char- erosion problem. acterized by very narrow beaches. Seawalls which are Protective rock revetment lines the shoreline be- common along this reach were constructed to protect tween Kaaawa Beach Park and Kalae-Oio Beach Park. beachfront property and the coastal highway from These structures were constructed to protect the erosion. coastal highway from erosion. There is little or no The 3,000-foot-long shoreline fronting the Punaluu beach seaward of the structures and waves run up Beach Park has been severely eroded. The shoreline very close to the revetment. The beach at Kalae-Oio along the northern half of the park consists of cobbles, Beach Park is 300 feet long and 80 feet wide, and boulders, and very little sand. Prior to 1955, large is composed of sand of calcareous origin. boulders were dumped along this sector in an effort The increased usage of beach parks along the east to protect the shoreline. A 40-foot-wide sandy beach shore and the increased demand for residential con- fronts the southern half of the park. The beach is rel- struction along these shores have focused attention on atively flat and composed of poorly sorted, medium to the erosion problems in this area. Erosion at four of coarse grains of calcareous sand. It was severely the six public beach parks is considered critical from eroded during the winter storms of 1968-69. the standpoint of the effect on the recreational useful- Artificial structures along the north and south sides ness of these beaches. The severity of the erosion of Kahana Bay flank a crescent-shaped barrier beach problem has resulted in requests from the State of at the head of the bay. The artificial structures con- Hawaii for Federal assistance in the construction of a sist of a boat launching facility on the north shore and beach erosion control project at the four parks, Ha- an ancient Hawaiian fishpond along the south shore. uula , Punaluu, Swanzy, and Kaaawva Beach Parks. The 100 -foot-wide barrier beach fronts a public beach Engineering studies of the erosion problem at the four park. The beach has a relatively flat slope and is parks are currently being conducted by the Corps of composed of poorly sorted, medium to fine grains of Engineers. calcareous limestone. A very shallow reef exists on the Kaneohe Bay and Mokapu Peninsula comprise the south side of the bay, and a sand-bottomed channel middle third section of the east shore. The northern leads out from the center. Sand in this channel, one half of the shoreline of Kaneohe Bay is primarily a of the largest on Oahu, is more than 15 feet deep. rural agricultural and residential area while the A very narrow gravel beach extends from Kahana southern half is a highly developed residential area. Bay to Swanzy Beach park. The landward limit of the Much of the shoreline along Kaneohe Bay is artificial, shoreline fronting Swanzy Beach Park is defined by the result of dredging and construction of fishponds and other structures, including open piers for recrea- a vertical masonry seawall. At mean low water, the tional craft. Because this bay has a deep lagoon be- beach seaward of the wall is about 20 to 30 feet tween an outer reef and the shore, the reef is con- material which ranges in size from sand to small boul- sidered by some geologists to be a barrier reef, the ders. A shallow coral reef extends about 1,500 feet only example of such in Hawaii. The low wave ener- seaward of the beach and is estimated to underlie gies within the bay preclude much reworking of the beach at an elevation of about -2 feet MLLW. The materials along the shore, resulting in the creation of winter storms of 1968-1969 severely damaged the small deltas through deposition of sediment from beach and undermined the protective seawall. Accre- streams entering the bay. The poorly sorted sediments tion which has historically occurred at this beach along this shoreline are sandy gravelly silt. Man- during summer months did not occur during the sum- grove has begun to grow at several locations and is 44 'Z. .. ........ . Fig. 2`1 Aerial view.6f Kaaawa Beach, Oahu Nvell established along the Heeia shores. Several all- The Coast'.11 reach from Kailtia 111;i\' to Mak-.ipim cient Hawaiian fishporlds, some of which are @being Point consists of two broad ba\s. Kaillia Kt\ L.lml-Avai- filled for residential development, , line the bay. rnanalo,.BaN, : whu 11 art, scl)"irated I bY. Lanikzn, a Sandy beaches exist only along the north end of tl@e broadly'("omex headjand, Developillelits J.11 1111is M'Cit p ba y. Beaches in this area are about.80 feet wide. The consist of a lllililai-i@ a*r basc and 1)..trk. 5' pLlhliC three beach parks along the bay are fronted by rnud- beach parks. a boat latiliching filcility, ;111(1 highly flats. developed residential arcas. Offshore, bia within.the. bav, lie extensive shallow The shoreline ayomid-the points Lit each clid of' the sand flats of irregular OLItline and sharp breaks, in the tN-,,o bays are rocky. but the@shi)n'fs between then) (oil- slope of the cora I reef. The, lagoon bottom is mud. The.@ sisl of fair to e Iwellctit bc.`wl The .1 beach fronti .jig niain channel that. eniers; from the north end, and Kaiiiia Bm- is abotit.2, nilics long, about 100 fcc I much of the south end of the 'bay have been dredged. wide along dic icsideiiiial bea(li and 150, feet wRk- at The bat-tier reef which. is broad and covered Avith sand. Kailtia Beach PM1 M-1hC1 S ,OLIth end of thc bay. The over- ITILIC11 Of 41S,S111-face. pro% vides 'effecti-Ve. pr.0tec Ition. bcachval-ICS tll.@SICCJAIC@s (foill.11-111 at the soutil end Against erosion Of the ..shoreline of the bav. lo. Steel> Ill the cenwr alld to inoduratek Steel) @11 @N-lokaptiP@iiiiistilii,x\-Iiiciiisdc%-clopeditito@iiNl@ti-li@c2 the north end. RcIlilld .1lic belich-ire old, \ cgc ta wd Corps air Station. separates Kaneohe Bi\- from Kailita dmiCs (A) Will'(11 bcaclifloill 1-t-sidt.11ces havc bccll (on- Bav., Becatise [lie [X@nillslila lvas formed by a sel .-les stl t1cled. 'Flic [)(.,1( 11 (onsist", of vcl-\@ poork. Sol,[(,([. of, volcalliC CRIPIloills. bedro@:k, of x01c;uil(' chAracter-, hi-lik calcal-cou." Crilic-,d closl0l) aloll Aal Istics forms much of (lie sl lorel i ne. The olll\. Iwo sandv of 3,000 [(.(.1 of tills bcach 11,1s (hrualclicd bc;wIlfront beaches are oll the I ')orth shore of' the peninsula. Thcsc rcsidclltlal propcr(\@. twaches are abom 100 feet N\-ldt- aiid are Itscd (or Lanlkai Beath \\hich is ',ibovit 7.000 fcci long and 60 fee t w I licadkilld be Marine Coips landing exercises. dc I'mills Ill( twccll 01c, Iwo. 45 1):INS. of ;I large but Shallow offshole N1,01-aptiti licadi Paik, ific shorclinc exict)(11fig froln and mo offshoic islands minimizes xvlavc Witinianalo Bay i(? Nl;kiputi Pmllt Is prilli;11-11N. bcd- a(iion oil the beach. As ' it result the beach has a rock (figure 22). The Nlakii R@inge pier lacility Is flat slope and the sand is poorly sorted. The north- Ihc onk. artificial Structure alolic'. this reach. "Yhe west end of the beach has been eroding and sand from bca(h fronting Kaupo Beach P@irk is about 3,300 this end has deposited along the southeast end. Much feet long and 50 feet wide, and is composed of of the beach is protected by Structures such as sea- calc@ircous sand. The pocket beach at Nlakaputt Beach walls and sniall Jetties, some of.which have been crit- Park is ',II)OLlt 900 feet long and 100 feet WidC. It is ically undermined by erosion. flanked oil the north by I Liva point and oil the south NValmanalo beach, south of Lanikai is the longest by a high sea cliff. continuous beach on Oahu. It curves gently around Waimanalo Bay for about 5 miles and ranges in width SUMMARY from 50 to 150 feet. The calcareous. sand is medium- to fine-grained and varies from well to poorly sorted. Oahu is the most lnghlV. Urbanized island of the The foreshore has a low slope and is generally cusped. State; Unlike the other major islands, approximately Behind the beach Ls a series. of low dunes which are one-half of the shorcline'of Oahti IS in IlltenSIVC use covered Nvith vegetation or by beaclifront residences. Which ill('ILjdes industria 11, militarv, resort, and res- 'clential developments. Be I I Shore ownership. along this long beach is divided I Cause ct-'t*cal erosion of between the military, the state, the County, and pri- these Shores Could SeriCIUSIN' affect their existing use. vate holdings. Bt!]IoN-.,s Air Force Base fronts 12,500 remedial action for these shores Would have a stronger feet of beach at the north end of the baV. Critical Justification than that for less developed reaches. erosion has occurred along a 2,000 foot reach at the Approximately 1,5.2 of the 198.5 milc@ of' shore north end of the Bellows beach. The severity of the frontage have been CrltiCallN eroded: LIhOUL 31.8 erosion has necessitated remedial action to protect Iniles have a history of erosion but ill(' problem is beaclifront propert%. not (ritical I( this time, and the reiriainint, 151.5 Except for saii(h, hea( lies at Katipo Beach.Park and miles have a history of, stability or accl,clion. g W 4g, AOM M_ q 4 5, J, s, M Fig. 22 Aerial view of the.shoreline between Katipo Beach Park and Makaptiu.Point. Oahu @hg K ,9-1 "'tz vlll 46 Hux LEGEND. p J: .SAND M LAIE GRAVEL "N i@ MUD (SILT&CLAY) HA LEI W"A M AtNA 01, OU14A t L U ROCK Ao ....... .......... .... _Na ARTIFICIAL STRUCTURES X -9 ,* "*Wj(A' kc- JAAKAMA WAI P I c) Ile 77 L) -\,KAMEO E -fx, "V KAUPA7 Apr PEARL HARA IN BARBERS PT. 4 M. I L E S SHORELINE PHYSICAL CHARACTERISTICS All ISLAND OF OAHU EL 3LVId .............. ... z 00, x J ao A O@m z Og o -C c ............ . . . . . .. . . . . . T- E MAN I a cy z mo rn W rm a C)z a Om > 0 a M M 0 0 z @z tv L 31VId* 9 to WE C m CD r- m > X --4 > 3@ m r Z C) z < r . . . . . . . . . . . . . . . . . . . . . I M -n ;o M z ......... M rn M Z .............. r ............. .:: . ...... ............ ............. M: ... ......... .... .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... .. ... . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . UD 1% X X. X cn ................. 0 30 ... ... .... .. Or" . ............ ......... m 0 ..... ....... LEGEND z > SAND ION CRITICAL EROS OF N x 1000 FT. OF SHORELINE. GRAVEL NON-CRITICAL e MUD EROSION OF (Silt & Clay) N x 1000 FT. OF SHORELINE ROCK ......... I - U.' ARTIFICIAL STRUCTURES -4V P 3 7W,_ > z > 2 IN4. xl@pl - Xly 1 2 4 N M I L E S SH.,0RWNE,_ EROSION- AREAS I ' L A N" 0. @'-b F', '06 S, I A-HU x (@QUTTWXRN HALF) L 91 31VId 'N't L f., A- IA, 41 x 41 30 . ......... , ,, I z- I",I,AllI lip' lie 'IL z yo Nil Yii- "*It z oll". vo 71 0-0 ftt@ C 474 z MIN \1 gel z --at 70 z 0 10 -41 VA - z m ILA 0 m iin .2 m Ao .. ....... HUK PT. ofm A r, , , I. I- .U. L 0 w miz ul t giz!X I'-,.,,, , " _...10 c A'. to :IE I -X 3b n to L Ins X LEGEND MR SAND CRITICAL EROSION M. Z OF N x 1000 FT. OF SHORELINE. m GRAVEL NON-CRITICAL 0. EROSION OF MUD' m m N xI000 FT. 0 !Silt & Clay) OF SHORELINE Vi Lo ROCK z 0 3 m k L E S ARTIFICIAL Tz > STRUCTURES hz-) Z a: , - , C ,3: SHORELINE EROSION AREAS > 0 ISLAND OF OAHU z > (NORTHERWHALF) > c: ISLAND OF MOLOKAI GENERAL The island of Molokai, the fifth largest in the state, Table 12 has an area of 260 square miles. It extends 38 miles Shoreline Land Use due east and west and has a maximum width of 10 Island of Molokai miles. The island was formed by the outpouring and (1962) coalescence of two volcanoes, both long extinct and Total Shoreline Sandy Beach now much cut and degraded by erosion. % of % of The tidal shoreline is 105.9 miles long. About 55 Land Use Miles Total Miles Total percent of the shoreline is physically inaccessible or Recreational-Public............... 0.9 0.9 0.8 3.4 only marginally accessible by land, and includes about Recreational-Private ............. 0.0 0.0 0.0 0.0 1l miles of sea cliffs which are more than 1,000 feet Non-Recreational Development .................. 7.8 7.1 3.3 11.3 high. The remaining 45 percent of the shoreline is physically accessible by land. Nearly half of the Undeveloped ....................... 97.2 91.7 19.1 82.3 accessible reaches consists of sandy beaches, most of Total ............................. 105.9 100.0 23.2 100.0 which are along the west Molokai shores. Plate 18 0ffshore islands excluded. and table 11 summarize the characteristics of the island's shoreline. Source: "Hawaii's Shoreline" prepared by the State of Table 11 Hawaii Department of Planning and Economic Develop- Shoreline Characteristics ment in 1965. Island of Molokai SHORELINE OWNERSHIP (1962) Table 13 and plate 20, the latest data on shoreline Characteristics Statute Miles Percent ownership, shows that most of the island's shore- Rock ......................... 53.0 50.1 line and sandy beaches are privately owned. The land Gravel ........................ 13.7 12.9 ownership reflected in the table is expected to remain Sand ........................ 24.6* 23.2 relatively static. Mud (Silt and Clay)............ 7.1 6.7 Artificial Structures ......... 7.5 7.1 Total ......................... 105.9 100. 0 Table 13 0ffshore islands excluded Shoreline Land 0wnership *Includes 1.4 mi1es of seasonal sand beaches where the pre- Island of Molokai dominant beach material is sand for only a part of the year (1962) Source: "Hawaii's Shoreline" prepared by the State of Total Shoreline Sandy Beach Hawaii Department of Planning and Economic Develop- % of % of ment in 1965. Owner Miles Total Miles Total Federal ....................... 2.2 2.1 0.0 0.0 SHORELINE USE Public (non-Federal)............ 16.5 15.6 3.2 13.8 Private ........................ 87.2 82.3 20.0 86.2 Shoreline use in 1962 is shown on plate 19 and summarized in table 12 which shows that 97.2 miles Total .......................... 105.9 100.0 23.2 100.0 or 91.7 percent of Molokai's shoreline is undeveloped. 0ffshore islands excluded. Most of the shoreline developments are along the Source: "Hawaii's Shoreline" prepared by the State of south shore. The north shore is essentially undeveloped Hawaii Department of Planning and Economic Develop- primarily because of extremely difficult accessibility. ment in 1965. The economy of the island, which is presently cen- tered around pineapple cultivation and cattle grazing, is expected to remain fairly static. Although the tour- PHYSICAL CHARACTERISTICS AND HISTORY ist industry is presently an insignificant factor in the OF SHORELINE island's economy, the west coast with its fine climate Table 14 describes the physical characteristics, and beaches has a recognized potential for resort ownership, use and condition of the principal sandy development. However, such development is not ex- beaches of Molokai. The following discussion sup- pected to be as rapid and extensive as on some of the plements the data in the table by providing general other major islands of the state. descriptions of the physical characteristics of the 53 Table 14 Characteristics of Principal Beaches on Molokai Stability Classification Length in 1,000 Feet Predominant Shore Ownership Length Width Type of Beach Shore Use in Linear Feet Critical Non-Critical ----- ----- Natural Artifical Beach Public Recreational Non- Composition Non-Federal Private Public Private Recreational Undeveloped Erosion Erosion Non-Eroding Southwest Shore Holena . .. . ........................... .... 5 10 15,000 100 X Calcareous X Kanalukaha ........ . .. .......... . .............. 10 10,000 100 X X 10,000 Northwest Shore Papohaku ..................................... 12 12,000 300 X Calcareous X 2,000 10,000 Kepuhi ................................................. 1 1,000 100 X X 1,000 Kawaaloa ......................................... 2 1,500 225 X X Moomomi .................................... 1 600 100 X X 6,110 North-Central Shore Kalaupapa .............................................. 3 3,000 75 X Volcanic X 1,000 Kalaemilo ................................ ........ 3 3,000 75 X Calcareous X Northeast Shore Halawa Bay ............................................. 300 40 X Volcanic X 300 Southeast Shore Pohakuloa to Pukoo Beaches (5 miles coastal beach, 3 miles of beaches) ..................... 8 8 16,000 20 X Calcareous X 11,000 1,000 Ft. Public, 15,000 Ft. Private shoreline of Molokai, and general assessments of tions every mile or so along the eastern part of the shoreline condition. For this discussion, the island was reef. Considerable red silt is being deposited on the divided into 6 sections. reef surface, but large patches of sandy bottom are Southeast Shore (plate 21). This reach extends from also present. Cape Halawa to Kamalo Harbor. Numerous small ru- South-Central Shore (plate 21). This reach extends ral communities are scattered along the southern two- from about one-fourth mile west of Kamalo Harbor to about a half mile west of Ooia Fishpond, and is the to about a half mile west of Fishpond and is the developed and is characterized by low sea cliffs, a most highly developed reach of the island. Kaunaka- few small pocket beaches, and minor reef develop- kai, the principal city and population center of Molo- ment. kai, lies within this reach. The shoreline from Cape Halawa to Kanaha Beach The shoreline from Kamalo Harbor to Kaunakakai is a physically inaccessible reach of sea cliffs. The is characterized by alternating stretches of sand, cliffs are about 100 feet high at Cape Halawa, but gravel, and artificial structures, primarily ancient Ha- generally less than 50 feet high to the southwest. wailan fishponds. Although the sandy beaches are of Kanaha Beach at the west end of the reach of sea considerable length, most of them are only a few feet cliffs is a small arcuate pocket beach about 65 feet wide. Gravel beaches are most common at the small wide and 175 feet long. It is characterized by a mod- deltas at the mouths of intermittent streams which erately steep foreslope and is composed of well sorted, drain the broadly convex slopes of east Molokai. Most coarse grains of calcareous limestone. The backshore of the fishponds are in a badly deteriorated condi- is marked by vegetation, and in some places by a 3- tion, and the ponds are silting rapidly. A shallow foot-high escarpment cut into alluvial fill. fringing reef which is more than a mile wide in places, The shoreline extending from Pohakuloa to Kama- extends along the Kaunakakai end of this reach (plate lo Harbor is predominantly artificial. Most of the 53 22). ancient Hawaiian fishponds on the coast of Molokai The shoreline fronting the town of Kaunakakai was are on the reef flat within this reach. Most of the altered by construction of a barge harbor in 1934. fishpond walls are in a badly deteriorated condition, This harbor, the principal port for the island, consists and the ponds are silting rapidly. of a dredged channel and barge basin 1,500 feet long, A narrow coastal plain built by the deltas of inter- 600 feet wide, and 23 feet deep, and a 2,700-foot-long mittent streams extend along this coast. There are paved mole with a wharf facility at the seaward end several reaches of sandy beaches between fishponds (figure 23). and mudflats, but most of them are very narrow. The shoreline west of Kaunakakai consists of Pebble beaches are common at the small deltas front- growths of mangrove over tidal mudflats. ing stream mouths. Southwest Shore (plate 21). Except for a barge A shallow fringing reef which is often more than a harbor and a Coast Guard reservation, the reach from mile wide extends along the southern two-thirds of Ooia Fishpond to Kaheu Gulch is undeveloped. Mud- the southeast shore. There are natural deep indenta- flats comprise the west end up to Pakanaka Fishpond. 54 Hic shoreline from the fishpond to Kolo Wharf Coll- of bcachrock, Storm bca( Iles, largc areas of sand dc- st.sts. of narrow beaches, some of which are primarily . posited inkind of dic hca4 hiock by storin waves, i I re sandy' while others, particularly those near stream common along this reat-tv. Kati-takalipo, the largest of' mouths, are cobble beaches. Small lengths of mixed iliese beaches. is about one nille long. The sand is Ic cobble and sand beaches, old fishpond walls, and well sorted, very coarse, extremely low in volcani mangrove also exist within this reach. The edge of the material and about two feet thick along the foreshore. fringing reef in this area; is about a mile offshore. Low vegetated duties exist 'along the backshore. The reef is being rapidly covered by red silt washed Kaunalu-Beach is a small pocket beach at the head down from cultivated and;grazed fields. of Kaunalu 'Bav north of Kaheu Gulch. Both ends of th's 60-foot-wide., 150-foot-long beach teri inate against boulders lying against basaltic rock which form the points, of the bay. The sand consists of well sorted, verv coarse grains of predominantly cal- careous material. A small unnamed pocket beach lies at the head of a small bay about a half-mile north of KaUlIa1U Bay. The beach partly bars -an unnarned Intermittent stream and is about 80 feet wide and 250 feet long.. A berm exists only where-the stream ineets the beach. The foreshore along the rest of the beach extends Ill- land with a steadv rise to a grass%" flat backshore area. The sand is poor]\, sorted and contains it sniall amount of volcanic material aniong the pvc(fornindill- ly calcareous grains. Northwest Share (plate 23). A ('()iist Guard rescr- vation at Illo Point and it, sniall saild-Illilling facility are the only developments along thc northwest shore Fig. 23 Aerial view of Kaunakakai Barge Harbor. Molokai which extends from KaUnalti Bay to about 3 miles cast of Kawitaloa Bay. Pocket beaches at the head Kolo Wharf is a 600-foot-long abandoned pier of tiny inlets interrupt the loi%` sea cliff from Kal-Inalu and wharf facility approximately 3.5miles east of the Bay to PUU Koai south of PapoliaklA Beach. Hale 0 Lono-Barge Harbor. The shoreline between One.of the finest in the state, PapohakU Beach the two facilities is a mixed cobble and sand beach lies between a lava headland 'at the south end and with an average %-.-Idth of 100 feet. It is generallN a cinder cone headland oil the north. This fairi'v sandier at both ends than in the middle. straight beach is 12,000 feet long, 300 feet wide, and The 'Hale 0 Lono Barge Harbor consists of -I consists of well sorted, coarse, medium grains of pre- 1,500-foot-long east- breakwater and a 1,100-foot- dominantly calcareous material (figure"24). The,sand' long west breakivater', an 18-foot deep, and- 500-foot- -private extends offshore f(@r ' about 1;200 feet. A square turning basin, and a 26046ot7.long wharf. This collql- 11clion company maintains a, permanent sand- privately operated facility was constructed in 1959. mining operation at the .southern end.of the beach. The shoreline from Hale 0 Lono to, Laau Point The year-round removal of saild is dependt'lit oil lil- consists of alternating stretches of beachrock and torial drift in ;I southerlN, direct'on. Hoi-vever,- (lite to it sa tidy. beaches. KanalUkalia, o'ne.6f the san,0 beaches 6mbination of excessivei'sand removal and to it will- within this-reach, is 10,000 feetJong,. 100 feet.wide.,, ter of sit ccessive southern storms which produccd a and primarily'c'Ornposed of calca'rebus sand. At one -thW-_ ( I -ift (hiring 1962 and 1963, critical not af I fittoral (it time this bei*ich had large, cleepcusps, with - beachrock Cr6slon the southern . cnd'of Ili(- bea(li washed exposed in. troughs except at the Nvestern Vild .'which blit Ille (111,11-1-ving operal loll. .Sincc [hit[ [Ilnc., the had a high,berm with it moderately steep foreslopt'. s,itl(l-lllllllllg facility has icstillicd opcrat'011. . The sand consisted of extremely well s.ortvd.coarse vh, cindcr (oncat dic north end of Papohaku Beach -natei it grains of.calcareous i -i@ 1. However, in early 196.2_ it from the 1,000-foot-long, 100-fooi-wide, sand n .iiiiing operations .were initiated and b\` sprill- be.Ull aCKci-mlil. This slightly arCUate bea.cl.1 is com- of that vear the beach was conipletely desti-med. posed of weI[ sorted, rnediLlIll r ills Of C dcareous - 1. : I . g a Although Much Of the beach has returned since, let:- sand., A steel) foreslope -reflects the Occurrence of mination of sand mi-ning, jagg .ed beachiock are still, plunging.breakers along this beach. exposed in sorne place* S. I'lic shoreline from Kepulli. Beach to 111o' Point -it ache and -avel, The shoreline arbUnd Laau Point to Kaheu Gulch consists of altern. Ing re. s of s'. and gi consists of lava basalt sea cliffs. and length%- stretches beaches as well its low sea @Aiffs. Thcsv cliff's grildilill- 55 froni about three nilles east of Kawaali)a Bay. to Ka- laupapa Peninsula is undexclopcd. Sca (liffs which are less than 50 feet high-- near Nloonionii Beach ex- tend to tile west end -of''i 'lie Kalatipapa Peninsula where they rise to about,1,700 feet. The on-ly three sandy' beaches within (he north- central shore lit, along tile west side of KalaLlpapa Peninsula. Data are avallable oil on1v two of these b -lies. KaIaLlpapa Beach, the south -nniost beach, ea( ei M -ide. The west isabout 3,000 feet long and 75 feet i% end of the beach terminates against a talus of boulders at the base of 1,600-foot4iigh sea cliffs, and the east end terminates against low outcrops of lava. The beach is subject to seasonal accretion and -osion. Beach sand consists of a well-sorted in* ei ix- ture of medium-sized gritins which aic largely vol- canic in origin and thetefore black in color. The 1xick- shore of the beach ends abruptly against a boulder talus at the base of-high cliffs. Thcre is no offshore reef; instead a sandy bottonl with a simp slopo, ex- T tends off the be. Fig. 24 Papohaku Beach, Molokai Except foi- tile KalaLlJ_)apa Barge Harbot, the coast L-Kiween KidaLlpapa Beach and Kalacindo Beach to tile north consists of low Outcrops of lava basalt. The barge harbor was improved by tile Corps of Engineers In 1967, and presently consists of a 114-foot rubble- Iv increase in height and are froln 100 to 500 feet 11101-Ind breakwater and a 0.6-acre entrance channel high along thi@ pl-i-ysically inaccessible reach between and basin area. Illo Point and Kapalauoa.. Tile 3,000-fooi-long, 75-foot-wide KaLiernilo Beach The reach bet%vQen Kapalaucla and N'loollionli immediately north of the LlYb;1n devulopment at Beach has one of tile most impressive dune develop- Kalal.lpalllil is SlLlbjCCt to SCitsonal accretion and ero- .inents in Hawaii. Between Kapalaucla and Kalaill slon. As Such, (If(- shoreline is sometimes marked by Beach, the dUlIC", extend 4.5 miles inland iind are exposures of lava and bcikchrock. In contrast to Ka- fed by three calcareous beaches (Kalani, Kawaaloa IaLlpapa Beach, this b('ach is composed of predomi,_ and Moomornl) to the north. The shoreline fronting iiantiv calcareous sand which is verv weil sorted and Kalani Beach consists of beachrock at the water:Jine, mediuni-gTained in size. A rocky bottorn with nurner, behind which lies a 100-foot-wide storm beach., OUS sand pockets extends offshore.. Kax,.,aaloa Beach which has a lengill. of 1,500 feet Exc Iept for storm beaches and p'atches of I)lo\,,?ii and an average width of 225 feet, is subject to sea- sand, the shoreline along,the north and eas-1 sides of sonal a ccretion and erosion. The sand is xvell sorted. Kalaupapa Peninsula consists of sea eliff's which rise coarse in size, and predominantly composed of cal- to about 100 feet at (lie southeast (orlicr. The shoreline from Ka- ca]VOUS grains. The foreshore is moderately steep and Northeast Shore (plate 93). As typically scalloped by large cusps. The backshore latipapit Peninsula to Cape.lialawa.is oil(- of tile mo@t is a series of sand duties built by the brisk trade- spectacular reaches of Hawaii's shoreline. This reach winds which siveep almost Coll till uous lv across this consists of sea cliffs which are more than 3,000 feet beach. Older duties, sorne of which have solidified, high in the central section ;uid about 100 feet high extend across tile island and are known as the 'Molo- at both ends (figures @5 and 26). It is interrupted by kai "Desert Strip." A coral reef lies about 250 feet large valleys at I-Valleia, Walkolu, PelekLltlLl, lVailau, offshore. Papalal-KI, and H@daiva, all of vd-fich have allUviated Moonionil Beacl@ is a 600-foot-long. 100-foot-xvide bottoms and some of x%:,hicli have beaches at the vallev pocket beach %%-Inch is separated frorn Kawaaloa Mouths. Beach Oil LhC XVCSt bv a rocky headland. Siind along -1711C shoreline fronting PclekUlli and Wailini Valleys this beach is ptedoninianily calcarcous. L.arge patches x lias a cobble-beach base which is (-O\'Cl('Ll I.)y sand of sand also exist off@holc. during the suninicr nionths. At Milaxvii Bit\-, if low North-Central Shore (plate 23.). Exccpt foz a Coast sca clift dit-i(les thc.shorch.11c ulk) IWO alcll@flc pock-cl GLE.1rd reSel'\',ltl0fl ',111d llrbill dC\C1OPluCl1L ill K;daLl- hcaclics, both of which are - backcd bv ;and dtines. papa. the shorelinc along this leach which extend Thc beach at ill(. Ilm st end of (11C hav colls'sls- 56 -s (oI ercd 4 cobbles and ))Oil l(k.1 -it ich al.c. scasoiiallN bv sand. 'Flic beach at the so itlicast end consists L of Xvell sorled, .11luditilli grai'lis of" Nolcal],(- fiagniclits 311d calcitreous nialcilal III about equal propor(folis. -ockv and covered @%`th botil- Offshore, thc bottoni is I ders out to about the 25-foot-&-pth. SCV0 SC, tacks, ivhich in-c parts of old scl cliff's kohitcd h%. s I marit-te crosion, exist offshoi.c. Sonic of, dIcIII are Inoue -et high. than 350 ft: wzl@ ma'.; u@ M,_ 1.1, SUMMARY A Me About 2.5 nilles of thc slimcline of 01c Islaild (A Molokai aue considered to- bc tilick-t-gollit, clitical erosion. About 9.1 of' flic 165.9 tvidcs of shoi(-lim- NX have it historN ol' uiosioii bitl O)c probicin is 11W 3 Critical it( tli*s 'nic. "I'llo.. 1011, t@ 94.3 Ili[ luixt. ahistorx (4 sla b*I I i I()I- m( I cl to, 1 Fig. 25 Sea*stack and steep seacliffs along the northeast coast of Molokai Y,,f 2. pL*4 0VM11&X'.'.'.1 Mf-,@,W Fig. 26 Aerial view of seacliffs along northeast coast. of Molokai (Camera Hawaii Photo) 57- sun= SL JIVId U. Wt c IA V z z c c CA Az Nz? 0 < --M I I" @ m tr V :& '4V rn 6C 6L UtIld Of 0 c c IK C ... ..... ......... xt t ..... ......... ......... .......... ......... c oz rm 0 A > Om > > \N) 0 > p z m A r )@, "'t -. 0 Z > in 09 OZ 31VId r m z > ...... ... m Z 0 z I -n ;u m z 70 z > ................. INO ON r- c b 0 X 19 tZ UVId H:)ino ngHV)l odtvNvwv>l INIOd nvvi 0 'HDVA 3NIHVMn)4ndV)f 'VHv)inlVNV)l MdSM'30MV9 ONOI 0 31VH 0 N31014 v > z C) rr, 0 > M. 'N -4 411 Z. -T5 W > OZ-Z -4 ;00 0.0 z 1?6 o0z;v 1, 1 .. ., v, N 9V C rn --q 0 - -M LK 4A rn CZE -4 a m m g MM At ZEN mo r- 0 0 Z. m Hod coo AA A, DV39 VHVNV.)l 719 U 31VId 0 c Ol to XK > -C > J, N-5; n Gt A CA -4 mm z 0 Do z m 51S- m ll@ .0 O)l, -- @k ell "n om m 0 x Vo ZM .99 Id FCC JIL%l AVG nlVNnv)i H:MS rOlVAMd! 04 "ik" r :H:)v3g H@DM vinSNIN A311VAJM*UVA- A311VA A -SM oom > > z &AZ -4 < iA A311YA nNn z rn Z;M m 0 C PH z r". A311VA n 0 In 1,1VA Yn 'A X3 oz-z MH no 0 %Oz 0 ;7 Z Avg In C - vmvl m LO A311VA VMVI E::-, 0 - z 4A VMVIW4 3d PIP 7 ISLAND OF LANAI GENERAL lation is expected to continue to decline due to The island of Lanai, an extinct shield-type volcano, out-migration. Unlike the island of Kauai,no re- has an area of 141 square miles. Most of the island is versal of Lanai's economic decline is foreseen in the a high plateau with a maximum elevation of 3,370 near future since no new developments such as resort feet above sea level. Lanai City, the only town on hotels and tourist destination centers have been the island,is located on the plateau at an elevation of planned for this island. The economy of the island 1,620 feet. would probably remain centered around pineapple The tidal shoreline is only 52.3 miles long,half of cultivation. which is rocky and physically inaccessible by land.A little less than half is accessible, of which nearly three-fourths is sandy beach. The characteristics of the island's shoreline are summarized in table 15 and Table 16 shown on plate 24. Shoreline Land Use Island of Lanai (1962) Table 15 Total Shoreline Sandy Beach Shoreline Charteristics % of % of Island of Lanai' Miles Total Miles Total (1962) Use Recreational --Public .. 0.7 1.3 0.6 3.3 Recreational --Private . 0.0 0.0 0.0 0.0 Characteristics Statute Miles Percent Non-Recreational Rock ............................. 30.1 58.1 Development .......... 0.8 1.5 0.1 0.5 Undeveloped .... ....... 50.8 97.2 17.5 96.2 Gravel ............................. 3.6 6.9 34.8 Total ... .............. 52.3 100.0 18.2 100.0 Sand ..................................... 18.2 Mud (Silt and Clay)................... 0.0 0.0 Artificial structures ............... 0.1 2.0 Offshore islands excluded. Total .............. 52.3 100.0 Source: "Hawaii's Shoreline," prepared by the State of ......................... Hawaii Department of Planning and Economic Deve1op- Offshore islands excluded. ment in 1965. Source: "Hawaii's Shoreline," prepared by the State of Hawaii Department of Planning and Economic Develop- ment in 1965. SHORELINE OWNERSHIP Almost all of the island of Lanai is owned by one SHORELINE USE large landholder who also owns 98.5 percent of the Shoreline use in 1962 is summarized in table 16. shoreline, including the 18.2 miles of sandy beaches Plate 25 shows that except for recreational develop- (plate 26). About 1 percent (0.5 mile) of the shoreline ment at Manele Bay and a barge harbor at Kaumala- is owned by the Federal Government and consists of pau, the island's shoreline is undeveloped. light stations operated by the U.S. Coast Guard. The No dynamic changes in development of the island's remaining 5 percent of the shoreline is owned by shoreline are anticipated. Lanai's already small popu- the State of Hawaii. Table 17 Characteristics of Principal Beaches on Lanai Stability Classification Length in 1,000 Feet Private Predom. Private Recrea- Critical Non-Critical Length Width Natural Beach Compo- Owned tional Use Undeveloped Name Erosion Erosion Non-Eroding Feet Feet Beach sition Shore Lin. Ft. Lin. Ft. Hulopoe Bay Beach ......... 2 1,500 100 X Calcareous X 1,500 Polahua ................... 1 5 9,000 150 X Calcareous X 9,000 Hauela .................... 5 5,000 35 X Volcanic X 5,000 PHYSICAL CHARACTERISTICS AND HISTORY 1)(.C()Ill(.s gl@idlj;llly IfIgh-1 '11(mg 111( 14) OF SHORELINE 'Manelc Kly. I)]]()[ to N-:1411 Table 17 desclilbcs (lie physical characteristics, existed at the I)(.;I(l (A M"11)(1c Mly, M101 Is bound OWIACI-Ship, Use, a,nd condii1on of the principal sandy b%- StVCp faults M) (IIC UiISI MId I)N: ii 1:1\@i IC11MV 011 beaches of Lanai.' The following discussion SLIPP@C- tile west. 'File northeast end of the bca(h consisted of' inents the da(a in the table by providing general coral sand and was separated fr()ui a largel I C@ 11 I ) ic to ,descriptions of the physical characteristics of the the southwest I)x a short reach of rocky shoic. Fhe shoreline and general assessments of shoreline condi- larger beach was nourished by dark basalt sediment, tions. For this discussion, the island was divided into and was therefore referred to is Black Manele Beach. two sections. This beach was modified in 1965 by const,ruction of West Shore. The reach extending from Kamaiki a small boat harbor. Artificial structures comprising Point to Polihua'Beach is primarily sea cliffs. Sandy the harbor include a 470-foot-long I'Libblernound beaches occur only at the head of Manele and Hulopoe breakwater extending f)'0111 LhC cast side of the bav, Bays and along, the northwest end of this reach. Three developed ': shoreline areas of the island are a launching rainp. and 12 finger pleis jigure 27). located along this shore, Manele Cone, I cinder and spatter cone which has A sea cliff which extends SOLIthwestward from a been extensively shaped by marine action, separates point near Kapoho Gulch is low for the first mile, Manele Bay from Flulol-)()c Bay. A small poukci bekch 7, 41IM A, W Fig. 27 Aerial view of M.anele Harbor, Lanai 66 lies at the head of a cove fromed by the east side of the cone which is a sea cliff and the west side which is a bench about five feet above sea level. The cone is now a peninsula which is tied to the main island by beach sediments that are still being deposited in Manele and Holopoe Bays. A 1,500-foot-long, 100-foot-wide arcuate pocket beach lies at the head of Hulopoe Bay. Boulders lying against lava points occur at each end of the beach which is composed of a mixture of medium and coarse grains of calcareous material. Low dunes and a beach park occupy the backshore. The foreslope is steep, a result of the large swells which attack the beach which is subject to seasonal accretion and erosion. The shoreline from Hulopoe Bay to Palaoa Point is generally a low sea cliff, The Kaholo Pali, whic rises to 1,000 feet in elevation just north of Palaoa Point, and is the highest sea cliff on Lanai. Kaumalapau Harbor, which essentially consists of a 400-foot-long barge whart fand a 250-foot-long break- water is privately owened. The harbor was constructed for exclusive use by barges, however, prior to con- struction of the Manele Small Boat Harbor, it accom- modated fishing vessels and other small craft. The harbor is the island's only interisland shipping terminal. Polihua Beach lies along the northwesternmost part of Lanai and is an excellent beach with large quantities of sand. It is about 9,000 feet long; with an average width of 150 feet. The beach is subject to seasonal changes. During the late fall, sand shifts to the eastern end of the beach, and by winter the eastern portion is built out to widths of over 350 feet. The reverse situation occurs during the summer when sand shifts westward. The sand is moderately well sorted, medium and coarse in grain size, and con- tains very little volcanic detritus. A low sea cliff occupies the backshore at the west end of the beach, whereas large, high dunes lie banck of the beach at the east end. The entire reach usually has a moderately steep foreshore, a result of large waves which fre- quently strike this beach. In addition to large waves, an extremely strong alongshore current sweeps west- ward along this beach. East Shore. Except for a small industrial develop- ment at Kaiolohia Bay, this reach is undeveloped. The shoreline extending from Polihua Beach to Kahokunui at the delta of a gulch consists of altermating stretches of beaches and mud and gravel at stream mouths. From Kahokunui to Halepalaoa Landing, the shore- line consists of narrow beaches of fine sand chiefly of detrital origin. Small deltas of pebbles and cobbles exist near stream mouths. Such a delta exists at Hauola Gulch were a continuous alluvial flat has been built out during historical time. A 5,000-foot-long, 35-foot-wide beach fronting the delta consists of gravel and moderately sorted, medium-sized sand composed almost entirely of olivine and lava frag- ments. The backshore is a poorly sorted mixture of mud and gravel which is intermittently washed sea- ward by Hanola Stream. The beach is relatively stable because of a protective reef which extends about 1,300 feet offshore (plate 27). Beaches along the reach extending from Halepalaoa to Makaiwa Point are composed of calcareous sand. However, beaches south of Makaiwa Point become coarser grained, and as the reef narrows past Naha the shore becomes a oebble and cobble beach which continues past Kapoho delta where a sea cliff begins. One of the longest stretches of fringing reefs in the state lies off the northeast coast of Lanai, In several places, the reef is more than 3,000 feet wide. Together with the island of Molokai and Mani, lthe reef protects the northeast shore from storm waves so that beaches along this shore are relatively stable. SUMMARY About 0.8 mile of the shoreline of the island of Lanai is undergoing critical erosion. About 2.3 of the 52.3 miles of shoreline have a history of erosion but the problem is not critical at this time. The remaining 49.2 miles have a history of stability or accretion. 89 IFZ UVId ....... .. N. W cl H N. N. ME N, > N"T 4A ... m CA z 0 m m . LW@ m -0 > Zm LA m 0 Om> "n:O r- oon Oz-z -n;o "" ;a o 0 CA x 0 z r- 0 Loi Z -4 tA -,A z c > fn 3100 x ZZ> 0 m "'s > 0:0 - Z!! > r- Ml"o=! ci; M C) > > r, C> m m z m 90 0 Z 0 > m 4 rn m )@- m 4A o M z (A 49 ST. UVId EN M \ I\ .: M. ......... a oz =-a z mo <z > om >-f. >r) m 0 mm 0 0 Z> Z AT CD ""0 V.0 T%4 a 0 om tc CA ol 9Z 31VI-d r-m 0 rn M z 3: CA rn fA so r IC z C) 0 JL LE 31VId M4, irk Ao Nz r ot In CA F-w n z 0 ISLAND OF MAUI GENERAL The island Of Maui is of volcanic origin and consists Table 19 of two major volcanic cones, the East Maui cone or Shoreline Land Use Haleakala Volcano and the West Maui cone, which Island of Maui are separated by an eight-mile wide isthmus formed (1962) by overlapping lava flows. Urban areas have been Total Shoreline Sandy Beach developed along physically accessible reaches of,the % of % of coast and along the lower slopes of. both volcanoes. Land Use Miles Total Miles Total The higher slopes are ussed primarily for watershed areas, ranches and small farms. The tidal shoreline is 159 miles long, about 59 percent of which is marginally or wholly inaccessible by land. The characteristics of the shoreline are smmarized in table 18 and shown on plate 28. Recreational-Public ........ 8.0 5.1 4.9 15.1 Recreational-Private ....... 0.0 0.0 0.0 0.0 Non-Recreational Development ................... 15.4 9.6 5.5 16.8 Undeveloped ...............I....... 135.4 85.3 22.2 68.1 Total .... .........158.8 100.0 32.6 100.0. Source: "Hawaii's Shoreline", prepared by the State of Hawaii Department of Planning and Economic Develop- Table 18 ment in 1965. Shoreline Characteristics Island of Maui (1962) Table 20 Characteristics Statute Miles Percent Shoreline Land Ownership Rock .................. .......... ...... .. 110.2 69.4 Island of Maui Gravel ...................................... 11.2 7.1 (1962) Sand .................. ..................... 33.7* 21.2 Total Shoreline Sandy Beach Mud (Silt and Clay).................. ........... 0.0 0.0 of % of Artificial structure ...... .......... .... 3.7 2.3 Miles Total Miles Total Owner Federal........................... 1.4 0.9 0.0 0.0 Public (non-Federal)................ 60.7 38.2 10.3 31.6 *Includes 1.) Miles of seasonal sand, beaches where the Private .............................. 96.7 60.9 22.3 68.4 predominant beach material is sand for only a part of the year. Total ................ .......... 158.8 100.0 32.6 100.0 Source: "Hawaii's Shoreline" prepared by the State of Source: "Hawaii's Shoreline", prepared by the State of Hawaii Department of Planning and Economic Develop- Hawaii Department of Planning and Economic Develope- ment in 1965. PHYSICAL CHARACTERISTICS AND HISTORY, plate 29 and Table 21 describes the physical characteristics, own PRECEDING PAGE BLANK X X X X X X X ;e X EL L2 @P 3i 55 25 mile north of Wailee is an undeveloped, physically basalt and sandy beaches, the larger of which are inaccessible reach characterized by sea cliffs and the at Baldwin Park and Lower Park. The 2,000-foot-long, absence of an offshore reef. The shoreline extending 75-foot-wide beach fronting Baldwin Park is primarily south to Kahului Harbor consists of rugged terrain composed of calcareous sand. The beach fronting the behind hills of dissected alluvial fans and older dunes, town of Lower Paia is slightly arcuate and about and lowlands of alluvium and shoreline deposits. 2,000, feet long and 80 feet wide. The sand is moder- Although low in elevation, the teach north of Waihee ately well sorted, and composed almost entireh of has no sand beaches. The reach of consolidated and fragments of calcareous origin. unconsolidated alluvium south of Waihee is fronted by North-Northeast Shore (plate 31). The shoreline a narrow beach of poorly sorted sand and gravel. extending from Maliko Bay to Keanae Point is an The 15,000-foot-long, 35-foot-wide, slightly arcuate. inaccessible, irregular reach of sea cliffs broken by beach at Waiehu is about a mile north of the mouth of a number of bays, some of which are partly drowned lao Stream. Sand along this beach is well sorted, river valleys. The sea cliffs rise from less than 100 very coarse in grain size, and is composed of equal feet at the west end to 400 feet near Honomanu Bay. amounts of volcanic And calcareous material. Vege- Sandy beaches exist only at the head of Honomanu tated sand dunes lie between the beach and its marshy, and Nuaailua Bays at the east end of this reach. hinterland. However, some of the other bays have shingle pocket An increase in the detrital portion of beach sedi- beaches. ment occurs along the reach fronting a swamp A broad, two-mile-wide headland at Keanae Point, between Waiehu and Iao Stream. formed by lava which flowed into the ocean from Artificial structures comprising the Kahului Deep- Haleakala, supports a small farming community. The Draft Harbor line most of the shoreline within Kahului sea cliffs around this headland are about 5 to 10 Bay. The existing harbor consists of a 2,315-foot-long feet high. Except far the relative isolated com- west breakwater; a 2,760-foot-long east breakwater; a munity at Keanae and a Coast Guard reservation at 600-foot-wide entrance channel between the break- the west end, this coast is undeveloped. There are no waters; a 2,400-foot-long, 2,050-foot-wide and 35- reefs along, this, coast; however, sea stacks are foot-deep harbor basin: a revetted spoil disposal area common. behind the west breakwater; and two concrete Northeast Shore (plate 31). Except for anport wharves on concrete piles on which are built storage and rural communities at Wailuanui and Hana Bays, sheds and other port facilities. Two beaches at the the reach extending from Keanae Point to Hana Bay head of the bay are separated by a revetment front- is undeveloped. The shoreline is characterized by sea ing a cluster of hotels. The beaches are composed, cliffs, most of which are between 20 and 30 feet of a mixture of sand and gravel. high, except near Kapukula where they rise to 200 Waihee Reef, the most prominent offshore feature feet. Pocket beaches exist at some of the bays and along the north central coast, extends from Waihee coves; however, except for the beach at Hana, they are Point to Kahului Harbor. It is about 1,000 feet wide only marginally accessible by.land. off Waihee and narrows to about half this width near The 700-foot-long, 100-foot-wide beach on the Kahului. southern shore of Hana Bay is bound by a lava point Spreckelsville Beach, a 13,000-foot-long-reach east at the northwest end and by, highway fill to the to Kahului Harbor is broken into a series of short southeast. Sand along this slightly arcuate beach is beaches by points of lava, boulders, and beachrock, well sorted and fine-grained. About three-fourths of and, by manmade groin systems which were con- the sand consists of detrital grains of fresh and structed to retain sand along, this reach. The beach weathered lava while about one-fourth is of calcareous sand is poorly sorted, with a bimodal distribution of origin. A seawall along the backshore provides pro- calcareous. grains ranging in size from cobble-sized tection for the beach park behind it. Offshore, the coralline gravel to medium-sized sand grains. Large sand continues at a gentle slope to a reef area in sand dunes lie behind the beach which. is about 50 the northern part of the bay. feet wide but varies in width due to natural causes The shoreline at the Southeast boundary of Hana and because of sand mining operations at the west, Beach has been altered by construction of a T- end. Lines of beachrock exposed at the waterline shaped pier which extends seaward from the highway about 800 feet offshore define, the limits of a former fill. The pier provides about 300 feet of berthing space shoreline, arid are evidence of continued erosion over for small craft and commercial tugs and barges which the years. An alonshore current to the west prevails call at this relatively isolated community, Plans for a except during southerly storms when the current is small boat harbor at the northwest end of the bay have reversed. been prepared by the Corps of Engineers and ap- The reach extending from Papaula Point to Maliko proved for construction by Congress. However, con- Bay is characterized by alternating stretches of lava struction funds have not been appropriated. This 75 Fedcral prop-tt (onsisls of consirticiion of it 1,230- s(attcrcd pockets. fooi-long rubbleniound breakwater, the landward 250 The slightly alcuale bca('-h ai Kcaw;&i1m is moic fcc( of which would be a revetted mole. This structure than 2,000 feet long and is bounAl by lava outcrops would shelter a turning area and harbor basin of about at both ends. The sand is fine-grained, well sorted, 200,000 square feet. Terminal and berthing facilities and almost entirely calcareous. It tends to move for the harbor would be constructed by the State of onshore and offshore during the year. Some sand is Hawaii. also blown inland and lost. During the winter of Southeast Shore (plate 32). The reach extending 1962-63, the beach was severely eroded by repeated southwest frorn Hana Bay to Mamalu Bay is un- storms from the south, which resulted in considerable developed except for a few small rural communities. damage to private beach homes on the low sandy Hamoa Beach at the head of Mokae Cove is one of terrace behind the beach. Thick sand lies off the several pocket beaches at the east end of this reach. middle section of the beach. A coral reef lies off The 1,000-foot -long, 100-foot-wide beach is bound by the north end, and lava predominates off the south 30-foot-high cliffs at both ends. The sand is well end. sorted, medium and fine in grain size, and composed Kalama Beach Park lies at the south end of a of calcareous fragments. It is 6 feet thick at mean narrow, almost continuous beach which extends to the lower low water, and even thicker towards the back- north of Kihei. The beach fronting the public park shore which is Occupied by a private surf club. is 4,000 feet long, 30 feet wide, and is composed of Sea cliffs ranging in height from 50 to a few very poorly sorted sand and gravel sediment primarily hundred feet dominate the reach west of Hamoa of calcareous origin, with only a small pci-centage of Beach. Beaches are rare and are primarily shingles of volcanic fragments. Although seasonal a(creiion and coral and basalt pebbles. The existence of sea erosion occur at this beach, the net cffect has been stacks and sea caves attest to the occurrence of erosion. Surveys made of this beach in 1912 and 1961 erosion along this coast. Mthough isolated coral heads showed that the shoreline receded 300 feet during are abundant, there are no exposed fringing coral this 49-year period, and has impaired the recreational reefs (plate 33). Usefulness of the beach park. In addition, the erosion South-Southeast Shore (plate 32). An extremely threatened the highway.embankment at the south end irregular shoreline composed of relatively young lava of the park and necessitated construction of a revet- basalt extends along the undeveloped and marginally ment of 500-POLind stone topped with larger-sized accessible reach 4etween Apole Point and La Perouse concrete block components. The severity of the ero- Bay. Sandy beaches exist only at Nuu and Huakini slot) problem warranted Federal participation in a Bays at the east end of this reach, and at the north- beach erosion control project which is currently under west end of La Perouse Bay. construction. The project provides for construction South Shore (plate 32)* Except for the urban of a 25-foot-wide berm along the length of the park, development of south Kihel, the reach from La and a 3,000-foot-long revetment seaward of the berm. Perouse Bay to Kalarna Park has been essentially The sloped revetment would protect the berm from undeveloped. The shoreline from Makena' to Keawa- erosion, and should encourage accretion, of sand on kapu is now scheduled for extensive rescirt- develop- the seaward side. . .. . 1, @ I1@ ment. The southern third of this reach is characterized South-Central Shore (plate 32). This reach extends by low cliffs of young lava basalt and is only from the north end'of Kdlarna Park, to Olowalu Wharf. marginally accessible by land. The northern two-thirds Except for a small boa-, hai-bor and residential and consists of a series of crescentic beaches between low, condominium developments along the shores of iNlaa- sea-cliff lava points. The largest of these beaches laea Bay, and a few scattered residences at Olowalu, lies south of the PuLi Olai cinder cone, and is 3,300 much of the shoreline fronting this reach is tin- feet long and 100 feet wide. It is predominantly com- developed. posed of a poorly sorted .mixture of almost all sand A number of locations along the Kihel shores at sizes of calcareous material, and includes some. fine the Southeast end of Maalaea Bav have a historv of graiel sizes as well. Duties covered with klawe trees erosion while other areas within this reach have .form the backshore. The foreshore is steep, a result accreted. In the Keokea hornesteads area north of of large waves which frequently strike the beach. Kalarna Park, residents have constructed seawalls to Makena Beach. another of the series of crescentic protect their properties from erosion. These structures beaches along this coast, is 1,000 feet long and have been relatively effective against local erosion, bound by lava points at each end. The sand is although a 75-foot-1011'9 wall 'was 8 feet seaward of calcareous, well sorted, and coarse in grain size. Ex- the high water line in 1967. Surveys made of the tensive dunes coNered with kiawe trees occupy the south Keokea area in 1912 ;md 196-4 showed that an backshore. The offshore area is rockv, with a thin average annual erosion rate of 1.48 cubic yards per vencer of sand overlying it. Sand is also found in foot of shore OCCUITC(l dLll_lllg tl1lS 52-year perlod. In 76 the north Keokea area, the annual rate of erosion was Maalaea Bay was altered by constrction of a re- 0.07 cubic yard per foot of shore. creational boat harbor by the State of Hawall. Several Substantial accretion has occurred along a 1.5-mile modifications have been made since that time Such reach of shoreline between Keokea and Kalepolepo. that the harbor presently consists of a 100-foot-wide, Comparison of surveys made in 1912 and 1961 shows 12-foot-deep entrance channel;" a 7.5-acre. 12-foot- that up to 200 feet of accretion had occurred in deep harbor basin; a 1,000-foot-long combination places within this reach. breakwater and mole structure; an 840-foot-long Artificial structures,primarily the seawalls of two breakwater; a 308-foot-ling, 50-foot-wide paved old Hawaiian fishponds, line the short reach of shore- wharf; berthing facilities for 43 boats; and a launching line fronting Kalepolepo. The southernmost pond ramps. covers 38 acres and consists of a semicircular rubble The shoreline from the small boat harbor to about wall which extends 1,100 feet seaward with a land 2 miles west of Papalaua Point is characterized by sea frontage of 1,700 feet. The pond has not been used cliffs in contrast to the low coast on both sides. The for years and the wall has almost completely deterior- sea cliffs between the boat harbor and Papalaua ated, although some rocks are visible above water at Point are relatively low, and contain a few tiny pocket low tide. The area within the smaller pond to the beaches. The cliffs west of Papalaua Point are gen- north had become dryland some time before 1900. erally higher and are bordered at the base by, a ter- However, around 1910 the old fishpond wall was race about five feet above sea level. Sea stacks dot breached and about half of he fill washed out to the offshore areas of this reach. Deep water occurs sea. The pond is about 800 feet wide and the outer close to land, particularly around Papalaua Point. wall is now about 250 feet from shore. The shore- but becomes ahallower at both ends of the reach. line at the north end of this pond experienced severe The low coast extending, to Olowalu Wharf consists erosion between 1900.and 1964. Surveys showed an of alternating stretches of narrow sandy beaches and average annual erosion rate of 2.5 cubic yards per lava outcrops. foot of shore during this 64-year period. Northwest Shore (plate 32). This reach between The shoreline from Kalepolepolepo to Kihei Memorial Olowalu and Napili is one of the most rapidly growing Park has also experienced critical erosion. Surveys areas on the island. Developments along the shore- capital of Hawaii and now a popular tourist attraction show an average annual erosion rate of 1.92 cubic line include the urban area of Lahaina, once the yards per foot of shore for the reach between Kalepo- capital of Hawaii and now a popular tourist attraction, the Lahaina-Kaanapali area, this rapidly developing lepo and the public park, and 1.04 cubic yards per and the resort area at Kaanapali. Often referred to as foot for the beach fronting the park. In 1963 the the Labaina-Kaanapali area, this rapidly developing County of Maui constructed a wooden wall in front of reach is the principal tourist destination center of the park pavilion to protect it from being undermined the island. by erosion. In 1964, the County also constructed a The shoreline between Olowalu and Lahaina has 200-foot-long revetment to protect the highway at the five sandy beaches between stretchs of lava out- south end of the park, One-ton rock was placed to a crops. The beaches are narrow and have a total length crest height of about 8 feet above mean lower low of between 7,000 and 8,000 feet. Makila Beach is water with a seaward slope of about 1 on 1.5. typical of the beches within this reach. During the The northern boundary of the Kihei shores is defined year, the 35-foot-width of this beach hardly changes.. However, the ratio of sand to gravel and boulders by the remains of the old Kihei whart. This wharf However, the ratio of sand to gravel and boulders was originally 200 feet long and provided fair- changes markedly. The sediment is an extremely grains of all sizes. A coral reef extends offshore, and weather accommodations for small craft, particu- poorly sorted mixture of both volcanic and calcareous larly fishing vessels. It was abondoned in 1952 grains of all sizes. A coral reef extends offshore, and marsh at the northeast end of the bay. Part of the is covered with gravel and boulders, but very few res, including whart. The Lahaina following construction of the Maalaea Boat Harbor patches of sand. the center section of the town (figure 28). It is at the southwest end of the bay. The outer portion of The reach from Lahaina to Mala Wharf is char- protected by a 1,000-foot-long breakwater whic is the wharf has since been destroyed by storms, and acterized by alternating reaches of sandy beaches seated on the fringing coral reef. The harbor which only about a 130-foot-long rubblemound stub reamins. and artificial structures, including seawalls, a small The shoreline extending along the head of Maalaea boat harbor, and an abondoned wharf. The Lahaina Bay, between the old Kihei Wharf, and the Maalaea Boat Harbor is an 80,000-square-foot harber fronting Boat Harbor, is a barrier beach with an average the center section of the town (figure 28). It is a withth of 75 feet. Outcrops of beachrock occur along protected by a 1,000-foot-long brreakwater which is has a launching ramp and capacity for 80 small Filgluccl's III Icspollse 10 @1 UC(JLICS( 11`0111 the State ()f 11,11 a( t.crist it, of (hc pullik, b)l this hc@t( 11, atc I lawali. Fhe ncxv harbor would bc located about. 2,000 evidence ()I ille Scas(mal occill-n-11(c ()I LI]-(. swells. Icct nordiwcst ol the existing harbor. North Shore (plate 31). 'I'll(- reach of sea cliffs The reach extending from the badly deteriorated between Napill and I-laktilice Point Is mic of the and abandoned Nlala Wharf to Hanakaoo Point con- most s(,(,iil( oil Maui. Except foi- two G)asl Guard sists of allernamig stretches of beachrock and sandy rcscrvaiions. rcsori howls, along Naplli Bay, and beaches. -I'll(, 12,0004 'ooi-long, 50-fooi-wide beach at sin;dl urban developments at the east and west clids, I lanakaoo Point is the most significant of the beaches IhC Sll()I('Iillt' ai0I),L1 I)IiS C'0aSI is LIIIdCVVl0pCd. wlihin this reach. The beach is generally subject to The western third of thP, (oast consists of sea scasonal accretion and erosion. However, during the cliffs 20 to 30 feet lilgli with several rocky pollits. past few years, critical erosion has occurred along the A few sniall sandy beaches exist I .11 pockets between northern half of the beach,. and has undermined a these points. One Such beach is the 1,000- foot- long, wooden triangulation tripod at the point. 100-foot-wide beach at the head of Napili Bay. Bound The 8,000-foot-long, 100-foot-wide beach at Kaana- by rocky cliffs at both. ends, this slightly arCLiate pali is immediately north of Hanakaoo Beach. Kekaa beach is composed of well sorted, medium-sized grains Point, a littoral cinder cone now covered with resort of calcarCOLIS sand. It is subject to some erosion, buildings, lies at the South end of this beach which is particularly during the , winter. A coral reef xvith subject to seasonal accretion and erosion (figure 29). large sand pockets lies offshore. Beach sand is well sorted, medium-sized grains of The 700-foot-long, 90-fooi-widc Fleming,, Bc;tch Is predominantly calcareous fragments. Rock- ridges and another of ilic pocket bcaclics almig tix - wcstcrn end s and pockets afternate offshore. A well-developed of the norili shore (figure' (I) wrilliliales , 3W: 'I'll(- Ilea henri and a motlerately steep foreshore which are J, Ilk q g . ..... @@ll,""i"".i@@.@@@@,@@",:",@@ .... .... . . . ..... . MW 01@ ";0"V- ;*,Mks g WK K". K Fig. 28 Aerial view of Lahaina Boat Harbor. Maui 78 ,N against rocky. points of la@a at both ends, and is SUMMARY cornposed of well sorted, coarse. predominantly Approximatcly 5.7 of ifie 1!'iS.8 milcs of shor(AIM, calcareous sedim 'ent. around the island of Nlaul havc'be6i critically croded; Hono.kahua Beach is a 1,500-foot-I.ong, 160-foot- about 14,8 miles have a historN of crosion bLJ1 th(- wide straight, beach between points of lava. It is problem is not critical at this time; and the winainin(' composed of well sorted, medium-sized grains of 138.3 miles have a historv of stabilitv oi- a((rciion. calcareous sand. Ironwood trees grow on the large dunes along the backshore. A thick layer of sand lies offshore. The middle third of the north shore.consists of sea cliffs 50 to 300 feet high., Smal] sand @,.beaches occur at' Keonehelele and Honokohau Bays'. Boulder and cobble beaches can be found at the heads of some, of the bays, particularlv near stream mouths.. Sea cliff's along the eastern third of the north shore range up to 600 feet in height. Some of the cliffs have near-vertical faces 20O.to 300 feet high. . . . . . . . . . . . c. . A v" 2, 'J, Fig. 29 Aerial view of Keanapali Coast, Maui (Ca .mera Hawaii Photo) 79 41, 3 . . . ...... J n@ f%I 4 Z@@x . . . . . . . . . . . -A W" U 11,11 Mr, 'M. :..y A ma W" -Ma .2 W Pp- f p. Nl- IS, al W5411 t @aip A" .. ...... . "'A 'Z 'Z@ Fig. 30 Flemings Beach, Maui (Camera Hawaii Photo) 80 LEGEND MUD HOHOKOHA, SAND (Silt & Clay) GRAVEL ROCK ARTIFICIAL STRUCTURES er ILUK LAHAINA.7@@ , 11604 -- 1 1 .......... E., k 5,4, Q ///, I s oiv @,Jjj A A 00 KIHEI A%.v, z ............ HA 2 0 1 2 3 4 f VYIA IlAt LES P-, YA SHORELINE. PHYSICAL CHARACTERISTICS ISLAND OF MAUI co LEGEND PUBLIC RECREATIONAL PRIVATE HOSOKOHI'A, RECREATIONAL NON-RECREATIONAL DEVELOPMENT UNDEVELOPED s V: 41 31 hk L AH ATNj@_--W-t';_p AILUX 00 wl A AALA KINEI 4 44 J* 4- ,.H.A L LA KA 0"t IL 14 v 0 1 3 2 I I- ,or M kL CS I d :@4 ., eoi,., %,*" .. ........ at! m H A) 31 A NO 1,11.0,000 "/1WI lkll SHORELINE LAND USE ISLANDOFMAUI OC 31VId rn X- r z z 0 w 2. f- z M, z r 0 V. m r- c z G) 0 0 r Z < M m M r -f7- r r m IL m z 30 c ro 30M c POOL to Z 30 z M r m z M, m -4 0 r x z LEGEND ... N.V. SAND EROSION OF NON-CRITICAL 0 N x 1000 FT. OF SHORELINE GRAVEL CRITICAL EROSION n OF N x.1000 FT. OF SHORELINE. MUD (SILT&CLAY) 2 0 ............ 00 ROCK U. > 71, ARTIFICIAL STRUCTURE 0 N" > > > S146MINt 06SION AWW &AND 00 MAW (NIbktWkitN HALF) z LEGEND A >> n ZZ NON-CRITICAL SAND > 5.0 EROSION OF 00 N x 1000 FT. OF SHORELINE 4 4 > GRAVEL 0 0 > CRITICAL EROSION 'ALF) OF N x 1000 FT. J, 1', M OF SHORELINE. MUD (Silt & Clay) Li 30 x L'AFWAINA: .......... . ROCK 2 ARTIFICIAL STRUCTURES Z > > z er, wo, r; 00 'Ail Af Z@ 4 P ........ ... 0 4 M% LES N, ........ ...... SHORELINE EROSION AREAS ISLAND OF MAUI (SOUTHERN HAL F) LEGEND CORAL REEF EXPOSED lH0.0K!j0..l _f @% 1 1, 1 011,Y, I 111, 111111111111,71111, AT MEAN LOWER LOW WATER X, 0:2 ol)p 1. K hl WAILUK L A H ATN A '-Z. v@ h 00 k AALA Yi ..........., K I H E I I///,- NA lip 'e, 0 Nv 16, MAKIN ....... --W P imtl 1, 11"m,ko vhfi loo, CORAL REEF ISLAND OF MAUI KH Ai@!, C, GENERAL ISLAND OF HAWAII The island of Hawaii, known as the "Big Island", is larger than all of the other islands combined. Its the land ownership pattern reflected in the table land area of 4,030 square miles comprises 62 percent is not expected to change drastically, it is expected of the land area of the state. The island is volcanic to be more dynamic than other islands of the statee origin, and was formed by the gradual emergency and because of the current emphasis on tourism and resort subsequent coalescence of five volcanoes, two of development. which, Mauna Loa and Kilauea, are still active. The tidal shoreline is 306 miles long, and 50 per- cent greater than that of Maui, the next largest island. About 90 percent of this coastline is rock, 80 percent of which is marginally or wholly inaccessible by land. Sandy beaches are relatively rare, and are tics of the island's shoreline are summarized in table Table 23 22 and shown on plate 34. Shoreline Land Use Island of Hawaii' Total Shoreline Sandy Beach %of %of Land Use Miles Total Miles Total Recreational-Public........ 11.0 13.4 0.6 3.4 Recreational-Private....... 0.0 0.0 0.0 0.0 Non-Recreational Undeveloped................ 218.4 71.8 17.5 90.2 Table 22 .......... .. ....... Shoreline Characteristics ........................ .. ..... Island of Hawaii (1962) Total ......................305.5 100.0 19.1 100.0 Characteristics Miles Percent *Offshore islands excluded. Rock ................ 274.7 89.9 Source: "Hawaii's Shoreline" prepared by the State of Ha- Gravel ................... 5.1 1.6 waii Department of Planning and Economic Development Sand .............. ...... 21.8* 7.2 in 1965. Artificial structures........ 3.9 1.3 Table 24 Shoreline Land Ownership Island of Hawaii Offshore islands excluded. (1962) *Includes 2.4 miles fo seasonal sand beaches where the Total Shoreline Sandy Beach predominant beach material is sand for only a part of the %of %of year. Owner Miles Total Miles Total Federal................ 31.5 10.3 0.0 0.0 Source: "Hawaii's Shoreline" prepared by the State of Ha- Public (non-Federal).... 102.5 33.6 7.8 40.2 waii Department of Planning and Economic Development Private................. 171.3 56.1 14.6 59.8 in 1965. Total.................. 305.3 100.0 19.4 100.0 I . ...................... ........ 8 Offshore islands excluded. Source: "Hawaii's Shoreline", prepared by the State of Ha- SHORELINE USE waii Department of Planning and Economic Development .................................. Like all of the other islands except Oahu, the shore- in 1965. line of the island of Hawaii is primarily open, unde- developed land (plate 35). Table 23 shows that non- PHYSICAL CHARACTERISTICS AND HISTORY recreational development comprises the second lar- OF SHORELINE gest use of the shoreline. Except for Hilo and Kailua- Table 23 describes the physical characteristic, own- Kona, urban development along the coastal zone ership, use, and condition of the principal sandy consists of scattered plantation towns and villages. beaches of Hawaii, The following discussion supple- ments the data in the table by providing general des- SHORELINE OWNERSHIP towns criptions of the physcial characteristic of the shore- Table 24 and plate 36, the latest data on shoreline line of Hawaii, and qualitative assessents of shore- ownership, show that private landholders control the largest percentage of Hawaii's shoreline. Although Table 25 Characteristics of Principal Beaches on the Island of Hawaii Stability Classification Length in 1,000 Feet Predominant Shore Ownership Shore Use in Linear Feet Critical Non-Critical Length Width Type of Beach Beach Public Recreational Non- Name Erosion Erosion Non-Eroding Feet Feet Natural Artifical Composition Federal Non-Federal Private Public Private Recreational Undeveloped East Shore Hilo Bay.. 1 400 35 X Volcanic X 100 Southeastern Shore Kaimu Black Sands .1 1,000 75 X Volcanic X 1,000 Kalapana (Harry K Brown Park)... 1 900 100 X Volcanic X 900 Punaluu Beach Park 1 900 70 X Volcanic X 900 Southwest Shore Hookena Beach Park 1 600 100 X Volcanic X 600 Kealakekua.. 1 600 60 X Calcareous X 600 Northwest Shore Disappearing Sands Beach - 300 50 X Calcareous X 300 North Kona Beaches 7 15,000 100 X Calcareous X X 15,000 Hapuna............... 2 2,200 160 X Calcareous X 1,200 1,000 Maurna Kea........... - 300 100 X Calcareous X 300 Spencer Beach Park... - 400 160 X Calcareous X 400 Northeast Shore Pololu Valley.... 1 1,200 125 X Volcanic 1,200 Waipio Valley.... 4 4,000 200 X Volcanic X X 4,000 1 7,500 Ft Public, 7,500 Ft Private. 2 4,200 Ft Public, l,000 Ft Private. Line conditions. For this discussion, the island was divided into 5 sections. East Shore (plate 37). This reach extends south from Waipio Valloey toCape Kumukahi, The northern half of this reach is primarily in agriculture, and the southern half is basically undeveloped. Hilo, the prin- cipal city of the island is located along the center sec- tion of this reach. The shoreline between Waipio Valley and Hilo Bay consists of sea cliffs which are from 100 to 200 feet high. A few small boulder beaches exist in small coves, and a terrace about five feet above mean sea level is present along much of the coast. Hilo Bay is a large bight in the center of this reach. The south and east shores of the bay are relatively flat and at low elevations, while the west shore is a rock bluff. The entrance to the bay lies between the bluff and a coral reef known as Blonde Reef, and is about one mile wide. The reef extends northwesterly from the southeast side of the bay and prpovides partial protection to the inner bay, creating a natural deep- water harbor. This site was developed into a commer- cial navigation harbor in 1930. Modifications since that time have made Hilo Harbor the second largest seaport in the state. The exidting harbor consists of a 10,080-foot-long rubblemound breakwater, a 35-foot- deep enurance channel, and a 1,400-foot-wide, 2,300- foot-long, and 35-foot-deep harbor basin, Terminal facilities include two piers, sheds, and pipelines for petroleum products, liquid fertilizer, and molasses, all of which are owned by the State of Hawaii. The Waiakea Peninsula west of Hilo Harbor sepa- rates the harbor from the Wailoa Sampan Basin near the mouth of the Wailoa River. This basin provides the only accommodations for commerical fishing ves- sels operating along the east coast of the island. A small beach averaging only about 400 feet long and 35 feet wide fronts Mooheau Park along the cen- ter section of the shoreline of Hilo Bay. The beach is bound by highway fill at its eastern and western ends, and is comp[osed almost entirely of volcanic rock fragments of sand size, with very few calcareous components. The sand exhibits moderately good sort- ing at about a medium-grain size. The present beach is the reminaant of what was a much wider beach during the previous century. Much of the former beach was lost during consturction of a railroad embankment aroung 1901. Following the 1946 tsunami, construct- tion of a wider highway fill along the railroad right- of-way further decreased the width of the beach. The offshore area is primarily lava rock with a thin veneer of mud and silt, Large blocks of concrete rubble which lie offshore were deposited by the 1960 tsumami. The shoreline between Hilo Bay and Cape Kumu- kahi is very irregular primarily because much of it consists of recent lava flows which have been little altered by wave action. However, the very low sea cliffs at Leleiwi Point are evidence of some coastal erosion along this reach which contains only three short reaches of sandy beach. Shoreline problems along the northeast coast have resulted primarily from the devastating action of tsunamis, rather than from long-term erosion pro- coess. The tsumunis of April 1946 aand May 1960 were particularly disastrous, The April 1946 tsunami caused approximately $28 Million dollars damage to Hilo and the immediate vicinity, and the loss of 96 88 IIN-cs, (figures 31 and 32). Tlic May 1960 Isunami r(fluced tile 1-1110 bayfiont area to rubble, and caused approximately $24 million dollars of damage to the Flilo area and the loss of 61 lives. J2@ Southeast Shore (plate 37). Except for a few scat- tezed'i-in-al communities, the shoreline between Cape 7 Kuniukalil and South Point is undeveloped. Most of dic inidevc-loped reaches',are marginally or totally Inaccessible by land. The shoreline between Cape Kumukahi and Kala- pana consists of low sea diffs and the constructional surface of recent lava flows. It is irregular from clinker masses, collapsed lava tubes, and other structures of lava flows. The rough outline of this coast is being gradually smoothed out by wave action, and would eventUaliv be transformed to low sea cliffs. Flq@ 32 Destruction along a section of Hilo Bay resulting from the tsunami of April 1, 1946 twi @S Fig. 31 Effects of the tsunami of April I .1946 oo the waterfront business area of Hilo, Hawaii 89 The slightly arctiate, 1,000-foot-long, and 75-foot- is composed almost entirely of black volcanic glass wide black sand beach at Kaimu (figure 33) is the which ranges in grain size from mediuin.:to very most 1)ut)liciz(,d of all the small black sand beaches coarsc. which have been created by the explosion and chil- Southwest Shore (plate 38). The coast froML South ling of lava flows -entering the ocean. The sand at Point to Keawekaheka Point north of Kealakekua this beach is composed almost entirely of volcanic Bay is inaccessible by land except for a few very glass and lava fragments which give the sand its rough jeep trails. A few small pocket beaches lie famed black color. The sand is moderately well along the 8-mile reach between Kauha Point and sorted and very coarse in size, and includes some Okoe Bay. The shoreline north of Okoe Bay is irregu- gravel-sized components. Critical erosion has reduced lar and consists of sea cliffs and faults, The cliffs are the beach to a 300-foot-long, 30-to 4d-foot-wide high where the faults are both close to and parallel to strip at the southwestern end. Lava rock and boulders the shoreline. Pali Kaholo between Hookena and are exposed at the southwestern en .d (figure 34) and Milolii follows a fault and is relatively high,, about cocontit. trees lining the backshore are being under- 500 feet at its maximum but less than 250 feet along mindcd (figure 35). Since 1900, the beach has eroded most of its length. However, the coast north of an average of about 275 feet along its entire length. Hookena and south of Milolii is flatter because of the The average annual rate of erosion is estimated to be absence of faults. Milolii Village is noteworthy as a 4 feet per year. The severity of the erosion problem Hawaiian village which is relatively isolated from led to a request from the County of Hawaii for other,communities, and is therefore one of the few Federal assistance in an erosion control project for communities with a nearly self-sufficient economy. this beach. Engineering plans to control the erosion Several littoral cones, formed by black basalt glass problem are currently being completed by the Corps from the explosion and chilling of lava flows entering of Engineers. the ocean, are present along the shoreline. A few The 900-foot-long, 100-foot-wide black sand beach small black sand beaches adjacent to the cones were fronting a public park at Kalapana is similar in formed by erosion of the cones. composition to that at Kaimu Beach. Much of this The 600-foot-long, 100-foot-wide arcuate pocket beach has been reduced to cobbles, a result of ero- beach at Hookena is one of the few sandy beaches sion and sand blown inland into dunes. within this reach. The beach is bound at each end The reach extending from Kalapana to South Point by basaltic rock and along the backshore by'a 100- is primarily sea cliffs formed by erosion of recent lava foot-high fault escapment of lava basalt (figure 36). flows. This reach contains only three sandy beaches, Nearly equal proportions of volcanic and . calcareous two of which front on undeveloped, marginally grains form the medium-sized, moderately sorted accessible land near South Point. The third beach sand which extends inland beneath a coconut grove fronts the vitlage of Punaluu, and is 900 feet long to the talus at the base of the fault escarpment. The and 70 feet wide. This slightly arcuate pocket beach sand extends about 100 feet from shore. q 6 r N,IWA 51 Moo= 00 Wt Fig. 33 Aerial view of Kaimu Beach on the island of Hawaii Fig. 34 Exposed lava rock and boulders at Kaimu Beach 90. A ;60O-1(m)I-1()IIg' 604(114-Widc llus a[ Ihr 111C Iiiqlll\' 111412,HLII (1011'WI 'd IWA' 'WN (1111", s4milicrn end of Kc@dakcky@l Bily. Thu salld is lx)oll@' Illis .((Oasl I. cs Ilion: ,,@IlldN 1)1.;Il Illall my Ilhc) simvd, coarse ill griln size, and COIISiSIS 01' a II_IiXtLII'C (141M (4 OIC ISkilld. ThC ht,;i( lic, ai(- iistitlk lj()( ket of' grains Xvillich aic sliglltl@ more calcareous . than bca( hes III slight bays lormcd 1;1%-;l I )v().jjc(-- volcanic. At sea level, patches of sand alternate lions, and lia\c high calcaicoms (ontcnt. v 1 1 A 300-foo t-long, 504()()t-%':idc beach south of Kaiiiia v ill lava and with bOLIlders and cobbles composed of I lava and coral. Similar rocks lie awash as far as 300 Ra@l is I)OIAllark known as Disappcaring m; M.agic fect frorn shore, after which it coral reef gently slopes Sands Beach lWCaLISC Of its Marked change hciA\tvn to a depill of 10 feet at a distance of 800 feet from the winter and summer months. During Ill(, the beach. Beyond this point, the reef drops off I(TOISiOll Win .piciely (IcimOcs ille beach. exposing la\a quite rapidly. and boulders m ill(, shorclinc (figure 38). 1 loxvcvcI-,: A sandy pocket beach once existed at Napoopoo during the summer, -I 2-1(@t)t-t-liick la.\-(-I, .)I' sand along the center section of the KealakekLia:Bay s.hore- (covers tll'c'r()(k at ill(, I'(MI.Shorc (figure. 39). I'lic'sand- line. However, this beach has been lost to erosion. is a well-sorted, im-ditlill-grailled mixture of' Northwest Shore (plate 38). Much of the reach dominanth calcateoits linicsimic Nvith a smtW per- between Kealakektia Bay and Upolu Pojnt is till- centage (4 vokalm dctmus. A cocomit grO\V ()CCLIJ@Wi developed. However. the rapidly expanding resort ilie backshorc which lisliall\ I-cuillis L*IS Salid through- developments along this "Gold Coast- (figure 37) mit: tile vcar. A largc sand poc kci Iving off'shore coji- are expected to alter the situation. Although nitich of taillstLI)IOSI I'L-Vt Of Sill )d d I I I-' I IP' t hCht.1111111 'I 1101tt 11 X M@, W, IN 'n U A 4 7, . . . . . . . . . . Fig. 35 Undermined cAcomd tree at Kaimu Beach 9.1 llcii( [I Park ;it(- two (-)I dic sinallcr pot kci bu@whcs ;it AlluchoOllialti and Lalltilptlal. 1*11c BoIsc Gis(@idc Corpoi@Oloii is ( tirictilly devc]- -a ill d Ic 'I I' I\ it p II Ila B( -;It I I. I I I oping (Ile an I I I , has completed it iicw a(lccss road ill(- aica. Bet- ween Hapuna Beach and Spcncei T@n k, the elabo- rate Mal-Inakea Beach Hotel has bc@eii built With a APR -al beach about 300 feet Ion g. small but beatit*ftil cot T -4 00 -it Spencer he -foot-long, 160-foot-Nvidc bviich Park at the south end of Kawaihae B@iv is the last of the sandv beaches along the northwest shore. This pocket beach Is bound bN@ lava points at each end. The sand is predominantly well sorted, medium-sized -ains of calcareous limestone. It is about 3.5 feet gi thick at mean lower low water. Offshore, the sand is about 2 feet thi 'ck for a distaricc of 300 feet where a shallow reef covered with algac ;tnd marked by nurnerOLIS sand pockets is exposed. Construction of Kawailiac Harbor in 1959 sub- stantially altered the natural shoreline along the north end of Kawaillae Bay. The harbor was created by dredging part of.an extensive coial reef which Fig. 36 Hookena Beach, Hawail extends about :1,000 feet seaNvard and more ihan a mile south along the shoreline. The second largest This pocket is believed to serNe its @i repositmy for harboron the Island, Kawailiae Harbor is primarily the eroded winter sand. it commercial navigaiion ft('iliL\'. HOW(W(A', dlC. State The short line along Kailua Bay'has been altered by of Hawaii has constructed two rt,cicational boat cons.t.ruction -of a conininiti-cial harbor at the north harbors, one at each end of the shoreside facilities for erld of the bav. The harbor consists of an approxi- the commercial navigation harbor. The c.,xisting Ka- rnately 500-foot-square turning basin, a barge pier wailiae Harbor consists of' a 400-to 520-foot wide, which extend,, Aout 350 feet into the bay, and a .2,900- foot -long, 40-foot-deep entrance channel, a launching ranip, 1, 250- foot -sq uare, 35-footldeep harbot: basin, and a Between Kailul-'t Bay and Houokohau, the shoreline 2,650-foot-long protective I'Libblernound breakwater. consists of 1,oxv sca cliff's at the terminus of recent fit response to it request from 'the @State of Hawaii, lava flows. The coastline at Honokohau about .4 the Corps of Engineers is developing plans for coil- nautical mil(-s north of Kailtia Bay has been altered struction of a recreational boat harbor immediatelN by construction of a small boat harbor. The Federal south of the existing revetted fill area for the coin- portion of.,di.c harbor, -completed in March 1970, mercial navigation -harbor. As part of a research and consists of a 14.5-,acre landlocked harbor basin rri@cle development program, the Corps has completed con- accessible to the sea by a 965-foot-long, 120-and struction of the entrance channel arid turning basin 160-foot-wide entrance channel. Construction, of the for the harbor, using an explosive cratering tech- pier and shoreside facilities to,, accommodate. the nIqUe. Ali 850-foot. breakwater has been constructed design capacli@ of 450 boats will be accomplished by to, protect the turning basin, arid a launching rarnp is the State of Hawaii. currently being const'ructed * ThC shol'Cline he(ween Honokohau and Kawaihae The remaining rc@wh 110111 K@lxvaill@tc to Upolli was undeveloped and physically inaccessible until Point is it marginallv :i(((-,si1)lc ;horclitic of moder- about 1964. This stretch of about 30 miles contains ately high sea cliffs. about 16 po(kc( beaches which ranges in size front Northeast Shore (plate 38). The n.ortheast shot-(. about 300 fv@@t ill length to the 2,200- foot -long, 160- from UPOILI Pollii to W"lipic, Valley Is Characterized fooi-wide bc@wh at l1aptina Bay (figure 40). Hence, by sca cliffs ranging front 100 to 1,400 feet in height. this 'NeCtOr ('01WIllis most of the relatively rare rec.- Devclopiiients along this shore are primarily rural Hawail. At I I reational bc@whes oil the -island of C011111111nitieS WhiCh are eCO110111'Cally ilcd to the sugar KmlPUlehLl Is the Kona Village Resort, I hotel whi(h ]-)I Lill U16011S IvInCh line fills Coast. has I private airstrip and all all-weath er paved road The sea cliffs between Upolu Point and Pololu Val- over iough lava flows to the highwaN. Three miles It-\- are of moderate height, while diose between noitheast ol this hotel is Kiliolo Bt\- which has a pololu and Waipio rise to about 1,400 feet. S1111111 pocket bcacli. Betwe(!jl Kiliolo Bay and HapLII1,I The sea cliffs southeast of Walpio Valley are much 92 Fig. 37 Resort developments along the Kona Coast; Hawaii loiver, rising to onIN- 200 feet. Deep %',I]IeVS SLICII as percentage of cakal-coLIS (0111polleills. The saild shifis POIOIU aiid lVaipio Valle%-s exist betiveen the steeper to the 'southeast end of tll(- beach during late fall and sea cliffs. These valleNs haNe sand. beaches at their to-the norillivest eiid dUrilig 'CdrI\ Sprillg. "FlILIS, it inoutlis, %%-Ith sand clunes b]oN\-n inland xvi-lich are as boulder [)each cxists at tile so.t,ithcast end dui ing the high as 50 feet. Spring S111111-tict, and c'ltly'fall" iind at tile llorth@v est -file 1,200- foot - Ion -.' 125-foot-Nvicfe fairly straight end during tlic xvintei. Neili-SI161C C111'relits are to tll(. beach at tile lilouth ,if Pololit Valley is cortiposed of northivest during Spring-, and 10 OIC SOLIthei';t durill" ivcll-sorted. triediuni-si 'zed detrital grains of la\a fiag- Ille fall. inclits (figure 41). Hic @;itnd is Inorc thim 3 fcct d(vp at sea level. A shalloxv, sandy bOtLOIII extends at IL'@Ist 250 fLTt Off,';11(-)I(' NVII(A-C OIC b0t1OIII dI-OpS Off .11 SUNIMARY a fairly Steep Sjopc. AppioximmeIN 2.1 lidics of thr 305.5 mllcs of I-11C.-beaCh at 111C 11IM111) 01' VAIC.N IS about '11olt-lilit, around I I IC Island of I linvaii h@lvu hcV I I 1 000 Icct Iorl@' @Illd 200 ILVI AVRIC (liticidl\ crodcd: abow 3.2 nillcs liave it It' tor\ (A (figtIrC -12 Sand 11 duilles lic behind dils sli"'ditl\- arctiate I)CItch 1\71lich is closioll 11111 dic probicill is I)()[ (11II(Al at Illis tillic; picklonlillailtl\ tolllposcd )f kv(.11-solu'd. dt)d III(. 1(.111@1111ing ')00.2 111 ilt-S hilvc it histolN. of :sized ,ia'ni of xolcmiic dc(i'tus, x6th oiil\. a sniall slabilil\ In Ictioll. 93 e4 OP. i: j 7- A 4@ N lK% A i Fig. 38 Disappearing Sands Beach. Hawaii, during the winter (West Hawaii Today Photo) 94 M.@'fv_ Tqpf' i 4 J'p 141, ilY R-1 '4' N. cl@ eo A,( LI& Fig. 39 Disappearing Sands Beach during the summer (West Hawaii Today Photo) 95 LEGEND SAND GRAVEL MUD I Silt & Clay I ROCK f ARTIFICIAL STRUCTURES KAWAI 41PI,,, 46" 0111'foklw/k ... I r z OWN' x'\' 0 2 4;@ M-A 'NA KEA W, \W4 Aot I L E G, zz-- J@ -V -H I L 0 K "W ze J11 -F@ -MAUP z KILAUE k OAT Z. Al If OUT PT SHORELINE PHYSICAL CHAR:ACTERISTICS ISLAND OF HAWA-11 PLATE 34 97 _"W,M Flq@ 40 Hapuna Beach, Hawaii Fig. 41 Pololu Boach, Hawaii ir4 Fig, @Vaipio- Be'kh Hjwaii 96 LEGEND PUBLIC RECREATIONAL . . . . . . . . . . PRIVATE 'RECREATIONAL L NON-RECREATIONAL 0 DEVELOPMENT ""HON A NA UNDEVELOPED lv// KAWAI @N N@ KLA= A Les A K I L KA _5 p-C ALI; 61 A, T CRA Y Z A Iv %vl N T F ell y- 10 s, 1@ S 711 Ill ff", 0,.l [W fit N SHORELINE, LAND USE ISLAND OF HAWAII T PLATE 35 ol 98 LAND, OWNERSHIP 1962 PT KAPAAU-NALAULA MANUXONA IPIO BAY PAAHAU 0 MORYN 40,000 PAAUILO SC@ALK IN FECT KAWAINAE OOWALA LAUPAHOEHOE PUAKO APALOA HAKALAU KIWOLO, BAY HONOMU PAPAIKOU HILO XAILUA DAY KIAMOU." CAPE KUMAKAHI XFALAKEXUA IIA HONAUNIAU DAY KALAPANA PAPA DAY LEGEND 4 PUNALUU, FEDERAL GOVERNMENT PUBL HONILOAOO IC (N 0. N@FE DERAL) P R I V A T E KALAEiSOLJT,H PT) 'PLATE 36 99 LEGEND N EROSION OF SAND ON-CRITICAL N x 1000 FT. OF SHORELINE GRAVEL. CRITICAL EROSION OF N x 1000 FT. OF SHORELINE. MUD (Silt & Clay) ROCK WAIP10 VALLEY ARTIFICIAL STRUCTURES AA1 L-ES A14 BAY A@' "rp CAM' 4111AUKA111 x6@@' Nn@ W", T @4 PLINALULI SHORELINE Ek&1014@ AR'IEA"S &AND OF 14' Widi' le.. (E"ASTERW HWi' PLATE 37 100 4, @iiblkk`#40TEL aAY"', .16 ACH' i@ 1"CH, K"PULMl 4 Otl K WkWt@, AI LEGEND POINT k--;4l'k SAND �@Q_ P@ _v- GRAVEL '4, MUD Isilt&cl.y) PALI' RQCK ARTIFICIAL STRUCTURES NON-CRITICAL EROSION OF x 1000 FT@ 'KAbNA;00iNT- OF SHORELINE CRITICAL EROSION :-r-"-SOUTH POINT V OF N x 1000 FT. OF SHORELINE. SHORELINE EROSION AREAS ISLAND OF HAWAII (WESTERN-,HALF) PLATE 38 101 woopw IMPROVEMENT., METHODS SUITABLE REMEDIAL MEASURES FEDERAL PROGRAMS, As defined earlier iri, this report, areas undergoing Under the direction of the Congress of the.'United eIrosion are considered. to be critical.. if the rate. of States, the Corps of Engineers has constructed shore erosion, when considered in conjunction with present proiection@and navigation projects for inany years. And projected (15 @years) economic., industrial,, rec- The , Corps' first, project in Hawaii was the. 1909 reational, agricultural, navigational, dernographic, authorization to modify Honolulu Harbor.,Currentlv. ecological and other. relevant factors, in,dicates.that the Corps of Engineers. office in Hawaii is undertaking action to halt erosion: -may be, justified.' Table 26- the projects and studies listed in tables 27 and 28, shows the 54 areas with a total shorelii-ie length of respectively.. All :of the projects and studies were more than 31 miles which,@are considered, to be:'..,, either directly or indi-iccily'authorized by the Congress critically eroding. Some, of. these areas require im-: and are the result of a request for Federal assistance mediate remedial action in the form of structural from State of Hawaii or county government agencies. improvements. The type of structural measure con- In addition to the studies currently in progress, sidered suitable to the particular, problem. area, is, table 28 lists the navigation and beach erosion studies included in the table. However, it is only a suggested which the Congress has. directed the Corps 'Of. Engi- method and is@ based on present knowledge of the:. neers to conduct with the objective of determining problem, projected. shoreline use, and current en- whether Federal assistance can be provided in devel- technology and experience in shore pro- opi ng a so lution tothe problein under investigation. tection works. Additional detailed investigation of SHORE PROTECTION TECHNOLOGY the problem and its@ impact on the en6ronment, And The. U.S.% Army Coastal EngineeYing Research -evaluation of the engineering and economic feasibility Cente A) has been of alternative Solutions are required before any solu ..r (formerly the Beach Erosion Boai studN ing shore 'erosion and.protection problems since tion can be implemented. 1930. The Center is.deeplv involved in investigations In addition to.the areas requiring immediaterreme. of shore processes, storm . frequencies, and stort-n-tide dial action, table 26. includes areas where remedial, elevations.- Research into remedial-, measures is ac- action would be. required within.5 to 15 years. The complishe'd at the Center by its engineers and type of improvement, required would depend on scientists; in addition, many significant p ograms are r whether effective coastal-,z6ne management is im- carried out by universities and private research organi- plemented.to minimize the adverse. effect of erosion zations under contracts with the Center. Much of -the on shoreline developments; Implementation of such Jield work essential to those research effor .ts is acconn- measures today would. reduce ' the extent. And. cost. of plished by @. staff mernbers@ of. the %'arious Corps of structural improvements which would:be xecluired. at Engineers Districts. The res'u16'of this research are a later date. Because it is difficult to predict.the, type published and widely 'disseminated in -the United of improvement which would be required, several States, and are also supplied on an exchange basis.to suitable types of remedial measures are suggested for foreign institutions and agencies. As a result of this these areas. exchange,' the Coastal Engineering Research Center The estimated cost of the remedial work su is well informed of world-wide progress. One of a ggested, series of publications prepared by the Center is Tech- in the table is based on 1971 price levels. in Hawaii, nical Report,No. 4, "Shore Protection, Planning and and totals about $32 million for the 54 areas. Design" which provides information And methods cur7 In order to: preserve the natural beauty 'of the rently used in the solution of shore protection prob- shoreline, protective.;vorks should be aesthetically lems. Technical Report No. 41 commonly known as, pleasing. This can be accomplished in part by a low- T.R. 4 among the Coastal Engineers of the world, profile-concept for groins and breakwaters. whereby provides the, most. comprehensive presentation of, these structures, would visibly extend only, a foot,or shore. protection technology available in a singlc soabove the sand -and water as depicted in'plate 39. In publication. (Complimentary to and less technical than some.. areas landscaped groins and islands should be [email protected] is the Center's Shoreline Protection Guidelines coiisidered. An example- of this type of treatment is Report which was published in 1971 as a part of the shown in the shoreline photograph of the Kahala, Hil- National Shoreline Study. The pfirpose of this report Hotel on Oahu (figure 1.0). is to enable State and local authorities to plan effective 103 PRECEDING PAGE BLAR9 tol r- r. K r- ;F E@ v ---,0 Coco 7; 55 55 x ^4 yk 5F cr Lp 2 zzzzzz z z 1: , -- z z )t :Z* )5 - - - - -- = @ ; 2 2 F F 7. 77 cr 77 L4 pj=pppps: PO X Q 5-e 7K' Q 5-K rl X R Le 5 a5 > > a cr 7 z z Z j@ z z Er 5 z cr 7 7 F 8 4A lz lz 1@ c "o. C C rM 7. 1 Z 7K a Table 27 Authorized Federal Projects for Hawaii As of April 1971 Types of Project Status Location Beach Erosion Completed in 1957 Waikiki Beach, Oahu Constructed in 1965 Haleiwa Beach Park, Oahu Under Construction Kihei Beach, Maui Pre-Construction Planning Kuhio Beach Sector, Waikiki Beach (being accomplished by the State of Hawaii, subject to Corps approval) Fort DeRussy-Royal Hawaiian Hotel Sector, Waikiki Beach, Oahu Design and Constuction to be accomplished Hanapepe Beach, Kauai by the State of Hawaii with 50% Federal Waimea Beach, Kauai reimbursement Pre-construction planning to be accom Duke Kahanamoku Sector, Waikiki Beach, plished upon recipt of project funds. Oahu Kuhio Beach-Elks Club Sector, Waikiki Beach, Oahu Navigation Completed Haleiwa Recreational Harbor, Oahu Hilo Harbor, Hawaii Honokohau Recreational Harbor, Hawaii Honolulu Harbor, Oahu Kahului Harbor, Maui Kalaupapa Harbor, Molokai Kaunakakai Harbor, Molokai Manele Recreational Harbor, Lanai Mawiliwili Harbor, Kauai Port Allen Harbor, Kauai Advertised for construction Kawaihae Commerical Navigation Habor Modification, Hawaii Pre-Construction planning Kawaihae Recreational Boat Harbor, Ha- waii Nawiliwili Recreational Boat Harbor,Kauai Lahaina Recreational Boat Harbor,Maui Honolulu Harbor Modification, Oahn Barbers Point Commerical Navigation Har- bor, Oahu Maunalua Recreational Boat Harbor, Oahu Kewalo Harbor, Oahu Preconstruction planning to be accom- Maalaea Recreastional Boat Harbor, Maui plished upon receipt of project funds Reeds Bay Recreational Boat Harbor, Ha- waii waii Waianae Recreational Boat Harbor, Oahu Ala Wai Boat Harbor, Oahu Hana Recreactional Boat and Barge Harbor, Maui Hanalei Recreational Boat Harbor, Kauai 106 CA Table 27 UP Types of Project Status Location Heeia Kea Recreational Boat Harbor, Oahu Kailua Recreational Boat Harbor, Oahu Kaunakakai Recreational Boat Harbor, Om- lokai Kaunakakai Commerical Navigation Har- bor, Molokai Kikiaola Recreational Boat Harbor, Kauai Nawiliwili Commerical Navigation Harbor, Oahu Table 28 Authorized Federal Studies for Hawaii As of April 1971 Type of Study Status Location Beach Erosion Under investigation Kaimu Beach, Hawaii Kaaawa Beach, Oahu Hanauma Beach, Oahu Hauula Beach, Oahu Punaluu Beach, Oahu Punaluu Beach, Hawaii Swanzy Beach, Oahu Maili Beach, Oahu Wailua Beach, Kauai Kona Area, West Hawaii Maunalua Bay, Oahu Mokuleia Area, Oahu Keehi Lagoon Area, Oahu Sandy Beach Park, Oahu Ewa Beach Park, Oahu Maile-Waianae Coast, Oahu Navigation Under investigation Maalaea Madium-Draft Harbor, Maui Kahului Harbor, Maui (Emergency Repair of Breakwater) Haleiwa Recreational Boat Harbor, Oahu (Harbor Modification) shore protection works. The report describes typical warning and high surf warning. The Tsunami Re- control structures, non-structural alternatives, ex- search Center is also planning to install six wave amples of present shore protection facilities, and gages in about 30 feet of water off the north shore of discusses their strengths and shortcomings, and pre- Oahu for a short, term research study entitled "Study sents criteria for' planning, designing, using and of Transformation of Ordinary Wind Wave Energy maintaining structural protection.) into Surf Beat and Edge Waves" which is being Present knowledge of shoreline processes in Hawaii funded by the National Science Foundation. reflects past studies that have developO, information For individual shoreline projects, the Corps of oil coastal currents, wave climate, beach profiles and 'Engineers supplements existing wave information materials, and the relationship. of beaches to reef With wave hindcasts of significant ocean storms perti- ecology. nent to the stud), area. There is a need for additional deep water wave re- COASTAL CURRENTS. search to provide a comprehensive statistical.report on The most complete published anal 'ysis of coastal the duration, height, period, and direction of waves currents around the Hawaiian Islands is contained in approaching the islands. the University of Hawaii's 1964 HIG-64-1 report. This work discusses coastal currents in terms of the various BEACH PROFILES AND MATERIALS. components which include the Pacific North Equato- The most complete compilation on beach profiles rial Current, the tidal current, wind-driven currents, and materials is contained in the University of Ha- arid wave-inducM currents. Drawings showing gen- waii's HIG-64-2 report, "Hawaiian Beach Systems." eralized current 'patterns around each of the major This report contains descriptions of 112 beaches, islands for both flood and ebb tide conditions are shows 150 beach profiles obtained during 1962 and shown. More extensive investigations are desirable 1963, and has grain-size parameters, oil about 2,400 to develop information on current patterns for inshore sand samples. areas. Research on water level buildup and current The Coastal Engineering Research Center funded patterns caused by breaking waves and onshore winds studies which are being conducted by the Corps of in shallow reef a Iieas.are needed. Engineers Pacific Ocean Division on eight- island WAVE CLIMATE. beaches. An analvsis on seasonal beach profiles arid sand samples obtained over a three year period will The most complete summary on the sources of existing wave data for the isla Irids is. contained in be correlated with existing wind arid wave data in an the Corps of En I ineers 1964 publication, "'Hawaiian effort to provide a better understanding of the com- 9 plex shoreline processes of the Hawaiian Islands. Island Beaches.- I The frequency of occurrence and meteorological SAND SOURCES. factors of the four principal sources of Hawaiian waves-northqast tradewind waves, northern swell Recent (1968, 1969, 1970) funding by the National from North Pacific winter storms, local storms, and Science Foundation has enabled the -University of Ha- southern sweil-are discussed in the University of wiali to initiate an inventory of offshore sand -deposits Hawaii's HIG-64-2 *report. throughout. the islands and to investigate the feasi- Wave records obtained at Kahului Harbor, Maui, bility of exploiting the deposits. The results of the during 1966 to 1968 have been analyzed by the first year of sand recovery study are published in the Coastal Engineering Research Center. The. University University's Department of Ocean Engineering's of Hawaii's*;Look Laboratory of Oceanographic En- Seagrant 69-4 report. The report summarized the gineering is currently obtaining continuous wave re- results of existing research of sand. uses and sand cords off the entrance to Kewalo Harbor, Oahu, in sources in the islands arid indicated that, at the pre- conjunction with a research study of surfing condi- sent rate of use of beach sand by the construction tions. The University's Hawaii Institute of Geophysics industrv, Haw-aiian beach sand resources would be is recording wave data in Kaneohe Bay, Oahu, which reduced by 25 percent within 10 years; that some sand v;ill be used in their research efforts to correlate wave is trapped in navigation channels and subsequently action with'coral reef growth arid damage. dredged and spoiled at sea; that beach sand from Iii'lq-1 1. the Tsunami Research Center installed two Molokai is the Current primary source of sand for wave gages oil the noi th shore of Oahu off the Moku- the construction industrv; that sand exploration has leia area in a joint effort between . the University of been chiefly concen trated in Kaneohe Bay -and Hale- Hawaii arid, the National Oceanic an 'd Atmospheric kulani Channel oil Oahu; thm Halekulani Channel Adillinistrat loll. :One gage is in about 1,500 feet of sand was rejected as a SOL11-Le for beach replenish- waterand one in about 100 feet of water. T lie program nient by the Corps and State officials because the isa Continuous prograin concet ned with both tsunami grain SUC Wa s too small and the color and odor were 108 LOW PROFILE. Offshore Breakwater, 'Groin'. Pa r Beac MLLW Z 'a Vol rar E 1 E P VC 1-S CT ONAi-VI.W c 0r a LOW PROFILE GROINS .40, 0 ral LOW PROFILE' 00 FSHbR0 BREAK If% WATER j 414 ISLAND BAR It IE ItS PLAN S CON C EPT A L FOR TYPICAL- HAWAIIAN BEACH ON SHALLOW REE FS PLATE 39 09 objectionable; that large quantities of the Kaneohe NATURAL DISASTERS AND SHORELINE Bay sand is suitable for beach replenishment but re- MANAGEMENT. moval has been prohibited by the State because of It is difficult, expensive, and in some cases, im- possible environmental effects on, a nearby bird ref- practicable or impossible to design and construct uge; that other known deposits in Kaneohe Bay are structures to protect the coast from natural disasters too fine-grained; that sand removal from water depths such as tsunamis, landslides, earthquakes, and ex- less than 50 feet is prohibited by State policy and tremely high surf. An efficient island-wide tsunami dredge capability.., has been limited to water depths of warning system has minimized the hazard to life less than 60 feet; and that it is not presently economi- from tsunamis, and zoning regulations are being cally feasible for.a commercial offshore sand mining developed that should substantially reduce property operation in Hawaii. The report concluded with the damage from future tsunamis in such historically sus- following statements-"Only theresults of a continued- ceptible areas as Hilo, Hawaii. inventory progra !m over the next few years, coupled An alternate to structural remedial measures for with unpredictable advances in ocean mining tech- some of the critical erosion areas along the north nology, will forrn the basis for conclusions of future shores of the islands might be through restrictive reports on the feasibility of recovery of sand from the. zoning and building regulations similar to themanage- ocean surrounding the Hawaiian Islands. Such reports ment methods being developed for areas highly sus- will be forthcoming as additional information -comes ceptible to tsunamis. The north shores are subjected to light." to extremely high surf from particularly severe storm About 160.000 cubic yards of shoaled material are conditions. Damages are primarily caused by flooding, dredged, on an average annual basis, from Hawaiian undermining, and direct wave'attacks on beachfront harbors by Federal hopper dredges and spoiled at sea.' properties and are most evident along well developed Methods of utilizing this material should be investi- coasts. During the extreme high surf of December gated. 1969, private property along Oahu's north shore sus- tained damages.of about one million dollars. A sug- gested land management alternative for the Mokuleia, Kawailoa, Sunset, Waialee, and Ka@vela beaches along RELATIONSHIP OF BEACHES TO REEF Oahu's north shore is a restrictive building code to ECOLOGY. require open type construction for the ground floor investigations dealing with the interrelationship of levels of beachfront properties. beaches and reef ecology have not been well pub- As part of the National Shoreline Stu&, the Corps licized. Rates of growth of reef organisms were of Engineers has published a Shore Management briefly discussed in the University's HIG reports Guidelines report. This report provides guidance to numbers 41 and 64-2. enable governmental agencies zit the State and County For the past three years, Sea Grant funds have levels to develop programs to improve the use and been used by the University of Hawaii's Institute of management of shoreline resources. Existing Federal Geophysics to investigate sedimentation, pollution, shore protection programs and policies and existing and other environmental' factors at Kaneohe- Bay, State and local programs are discussed. Historic and Oahu. Preliminary findings indicate that live coral anticipated shore uses are described, principles of is being killed by pollution and the reef in this bay is comprehensive planning accompanied by examples eroding faster than it is being replaced by growing are presented, mUltiple-Use of shore and water areas, coral, land use planning and construction are developed. The Additional research is warranted to expand present report also discusses the principles of cost sharing knowledge on the effects of shoreline project's on and describes t .he nature of public and private bene- reef ecology and the nearshore environment. fits. 110 COASTAL ZONE INFORMATION CENTER 3 6668 00001 6420