[From the U.S. Government Printing Office, www.gpo.gov]
































                       IDENTIFICATION AND ASSESSMENT OF TECHNICAL
                        INFORMATION REQUIREMENTS FOR DEVELOPING
                         COASTAL EROSION MANAGEMENT STRATEGIES



                               Proceedings of a Workshop
                              Held February 24 - 25, 1989






                      Convened by: Jay Tanski
                                    New York Sea Grant Extension
                                      Program
                                    State University of New York
                                      at Stony Brook

                                    Henry Bokuniewicz
                                    Marine Sciences Research Center
                                    State University of New York
                                      at Stony Brook








         April 1989












                                  ACKNOWLEDGEMENTS

         We are extremely grateful to the workshop participants; Drs. Robert
         G. Dean, Craig Everts, Nicholas C. Kraus, and Choule J. Sonu whose
          considerable expertise and cooperation made this effort possible.
         We would like to thank Mmes. Carol Case, Mary Lou Johnstone, and
         Eileen Goldsmith for their administrative and secretarial support.
         We are also grateful to Messrs. DeWitt Davies, Mike Volpe, and Ron
         Verbarg of the Long Island Regional Planning Boards for their
         assistance in carrying out this project.

         Funding for the workshop was provided by the New York State
         Department of State, Division of Coastal Resources and Waterfront
         Revitalization through the Long Island Regional Planning Board.































    1Z


         This document was prepared for the New York State Department of
         State, Division of Coastal Resources and Waterfront Revitalization,
   @'J   with Financial assistance from the office of ocean and Coastal
         Resource Management, National oceanic and Atmospheric
         Administration, (Grant-In-Aid-Award No. NA-82-AA-D-CZ068) provided
         under the Coastal Zone Management Act of 1972 as amended.




















                                    TABLE OF,CONTENTS



          Introduction  ...................................................   1

               Background  ................................................   1
               Workshop Goals   ............................................  1
               Procedure  .................................................   1

          Objectives of an Erosion Management Program      ...................2

          Technical Information Needs   ....................................  4

               Characterization of Coastal Features and Changes     ..........5
               Physical Forcings Affecting Coastal Changes     ...............7
               Land Use Patterns and Trends    .............................. 9

          Applications of Identified Information Needs     .................. 10

               Coastal Inlets   ...........................................  10
               Bulkhead Construction   ....................................  11
               Armoring of Coastal Bluffs    ............................... 14

          Appendix A (Attendees)   ........................................  16

          Appendix B (Background Materials)    ............................. 17

          Appendix C  ....................................................   21

          Appendix D (Shoreline Processes)    .............................. 22











                                     INTRODUCTION


          Background

          In response to erosion and flooding problems encountered along
          the south shore of Long Island, the New York State Department of
          State, Division of Coastal Resources and Waterfront Revitalization
          and the Long Island Regional Planning Board are in the process of
          developing a shoreline development management plan that is
          cognizant of coastal erosion conditions for this area. The
          preparation of the plan is to include an examination and analysis
          of the environmental, economic, land use and regulatory factors
          affecting development and erosion control decisions along the
          coast for the purpose of formulating a comprehensive, coordinated
          response to chronic flooding and erosion conditions on the south
          shore.


          In conjunction with this effort, a series of three workshops is
          being held to bring together experts in coastal processes and
          engineering to examine erosion problems encountered along Long
          Island's south shore and possible means available for dealing
          with these problems from a technical perspective. More
          specifically, the individual workshops have been designed to
          focus on 1) identifying the generic physical data and information
          needed to develop a sound coastal erosion management program, 2)
          identifying the technical data presently available for the south
          shore, and 3) if possible, using these data to discriminate among
          the various available,erosion control strategies for regional
          reaches of the coast in terms of potential effectiveness and
          impacts.

               The intent of these workshops is to provide technical
          information that will assist government officials and other
          interested parties in identifying, assessing, and selecting
          appropriate erosion management strategies for a particular area.
          This report summarizes the findings of the first workshop in this
          series.

          WorkshoR Goals

          The specific goals of this meeting were to:

               1)  Define the technical information needed to identify,
                   develop and evaluate sound erosion management strategies.

               2)  Identify the specific data required to provide the
                   necessary information.

               3)  Delineate why that information is needed and, to the
                   extent possible, how it would be used.


          Procedure

          To achieve these goals, four international experts in the field









          of coastal processes and engineering were invited to participate
          in the first workshop (See Appendix A). Prior to the meeting,
          the participants were provided with a preliminary list of
          potential technical information needs as well as a set of generic
          objectives for a hypothetical erosion management program. Using
          these materials as a starting point, the participants were asked
          to develop a list of information they would require to make a
          technical recommendation concerning the type of erosion control
          measures best suited for an ocean coastal region. (Background
          materials.on the procedure used are provided in Appendix B.)

          At the meeting, the information requirements identified by the
          participants were presented and discussed by the entire group in
          light of the workshop goals listed above. To help illustrate the
          practical applications of this information, the group was also
          asked to consider several hypothetical situations typical of
          erosion management problems found along the coast and specify the
          information they would need to develop an informed response to
          the particular situation and, to the extent possible, how this
          information would be used.

          The results of the group's efforts are reported in the following
          sections.



                     OBJECTIVES QF AN EROSION NANAG04ENT PROGRAM


          The purpose of this workshop was to identify the information
          needed to make a preliminary technical evaluation of the most
          appropriate erosion management strategy or erosion control
          alternative for an area. This process depends to a large extent
          on the anticipated objectives of an erosion management program.
          These objectives, usually developed as a part of the overall
          management plan for an area, are often decided on the basis of
          socio-economic factors which were well beyond the scope of this
          meeting. However, because an understanding of the objectives of
          an erosion management program is essential to the technical
          planning considerations that were the primary focus of this
          workshop, the group agreed to assume that any program would have
          the following objectives when it was necessary to do so in order
          to continue discussions. (Note: the following statement
          describing general program objectives was developed primarily by
          Dr. Dean, whereas the section on specific program objectives was
          derived, in part, from information provided by the Long Island
          Regional Planning Board.)

          General Program objectives: A management program should seek to
          maximize the broad public interests and benefits along the south
          shore of Long Island, for present and future generations. While
          respecting the rights of the upland property owners, the program
          should, where practicable, seek to restore natural processes,
          maximize public access, minimize storm damage and reduce or
          eliminate inequities which exist or could result from various
          activities under the program.


                                     2









         in recognition of the dynamics of coastal processes and the
         evolving use patterns along the shoreline, the program should be
         updated every 10 years with the modified elements of the program
         subject to public hearing review and comment prior to adoption.

         Ultimately, the program should be used to consider and develop
         recommendations on a case-by-case basis for all permit activities
         which have the potential of modifying the sand flows and littoral
         processes along the south shore including, but not limited to:
         coastal protection structures, beach nourishment, bypassing at
         inlets, and closing new inlets. Where appropriate, the program
         should be proactive in developing plans.


         Specific Program Objectives: More definitive program objectives
         may include:

               1.  Maintain and enhance as necessary the beach/dune system
                   of recreational beaches. The relevant concern is
                   primarily the width of the beach but would also include
                   the quality of sand, the state of the dunes, and
                   amenities such as access and facilities.

               2.  Hold the shoreline position and maintain the shore's
                   general configuration in urban areas. "Urban area" will
                   be defined by the Planning Board based on the permanent
                   population density, the type of housing, the degree of
                   commercial use, the infrastructure (streets, sewers,
                   etc.) and perhaps other similar criteria.

               3.  Maintain and stabilize existing inlets and provide for
                   adequate by-passing of sand across the inlets to
                   downdrift beaches. (What constitutes "adequate by-
                   passing" is discussed on page 10 of this report.)

               4.  Prevent new inlets from forming. This objective is
                   designed both to protect the investment associated with
                   existing stabilized inlets and to avoid potentially
                   adverse changes in the back-bay environments such as
                   salinity changes that might affect shell fishing or
                   enhanced bay flooding.

               5.  Maintain and enhance existing dune systems.

               6.  minimize damage due to coastal flooding.

               7.  Prevent adverse downdrift effects due to existing or
                   proposed erosion control measures and/or other coastal
                   activities or practices.


         Program Implementation: To implement an erosion management
         program on a technically sound and legally defensible basis, it
         will be necessary to collect, maintain and continue the


                                     3








          acquisition of certain data and information on the natural
          coastal system which relate to appropriate program decisions.
          These data needs are detailed below. In general, they define
          shoreline changes, land use, the physical characteristics of the
          coast and the phenomena responsible for changes in the natural
          systems, primarily waves.

          Basically, this technical and physical information is needed for
          four principal reasons:

               1.  To define the problem, including estimates of erosional
                   risk, storm vulnerability and the expected degree of
                   natural restoration after an erosion event for different

                   areas.


               2.  To provide a sound technical basis for legally defending
                   management and regulatory decisions.

               3.  To more accurately calculate cost/benefit ratios and
                   better assess risks associated with a proposed project.
                   The benefits will be largely defined by the management
                   policy, but estimating the cost of a proposed project
                   requires a relatively detailed design and this can only
                   be done with adequate site-specific data.

               4.  To understand the causes and effects of the observed
                   shoreline behavior. This is necessary in order to
                   estimate the effectiveness and potential impacts of any
                   proposed solution (i.e., the probability of success).
                   Our understanding is embodied in a model of shoreline
                   behavior. This could be a conceptual model or a
                   mathematical model, but some degree of quantification
                   is essential. Site-specific information is needed to
                   calibrate and to use the models as a tool for better
                   assessing management decisions.


                    TECHNICAL INFORMATION NEED5 AND REQUIEBMMTS


          The technical and physical data and information required to
          develop and evaluate erosion management strategies can be grouped
          into three broad, interrelated categories: characterization of
          coastal features and changes, physical forcings affecting
          coastal changes (i.e. waves, water levels, etc.) and land use
          patterns and trends.   The specific information related to each
          of these categories is delineated below along with an assessment
          of the data required to obtain the information and, where
          possible, suggested methods or recommendations for acquiring this
          data. (Group discussions on the informational needs were based
          largely on a table of data requirements provided by Dr. Kraus
          (Appendix C).)





                                     4









          Characterization of Coastal Features and Changes

           An assessment and quantification of the physical characteristics
          and the changes occurring in a coastal area is essential in the
          development and evaluation of erosion control strategies. These
          changes include variations in the position and configuration of
          the shoreline and in the volumetric sediment budget in an area.
          The assessment of these changes actually involves two levels of
          effort. The most basic level of information needed to begin
          developing an effective approach to erosion management is usually
          derived from direct measurements of the extent and magnitude of
          the effects of erosion on the coast. This fundamental level of
          information is outlined in this section. To strengthen and
          improve decision making capabilities, the results of these efforts
          (along with some additional data) can then be used to interpret
          and develop a better understanding the complex interactions of
          the coastal processes and conditions controlling sediment
          transport and causing erosion. The topics requiring this higher
          level of effort are described in a separate section under the
          heading "Shoreline Processes" (Appendix D).

          The basic information required for characterizing coastal
          features  and changes include:

                1.  long-term and short-term trends in shoreline migrations
                2.  magnitude of shoreline changes caused by storms
                3.  volumetric changes occurring along the shore
                4.  volume of dune erosion and rate of dune rebuilding
                5.  effects of existing structures.

          The data  needed to obtain the above information include:

                1.  sequential shoreline positions through time
                2.  sequential beach/dune/offshore profiles (to the closure
                    depth)
                3.  shoreline orientation
                4.  description of the regional geologic setting including
                    sediment grain size distributions
                5.  historical dune volume changes
                6.  volume of ebb and flood deltas at inlets
                7.  overwash frequency and volume.
                8.  inventory of shoreline protective structures including;
                      a.  location, size and orientation
                      b.  porosity, permeability, refection and transmission
                          characteristics
                      C.  location, volume and schedule of beach fills,
                          dredging and sand mining operations
                      d.  aerial photographs, plans and surveys associated
                          with these projects.


           The information on coastal changes is needed to:

                1. Define the erosion problem with respect to time and
                    location and to make a preliminary assessment of the


                                      5








                   ,.eve! and type of effort required to mitigate erosion
                   trends. For example, in a particular area, a
                   documented high chronic rate of shoreline recession
                   over the long term would indicate that utilization of
                   beach nourishment may not be cost effective and that
                   retreat or a structural response would be required to
                   mitigate problems associated with erosion. Conversely,
                   a low long-term recession rate could indicate the local
                   sediment budget is only slightly out of balance and
                   that beach renourishment may be an effective measure
                   of erosion control.

               2.  Forecast the range of expected shoreline changes at a
                   site in order to:

                   a.  establish appropriate, legally defensible setback
                       requirements. (It was pointed out that the profile
                       and historical shoreline change data collected by
                       the state of Florida have been used successfully in
                       defending the state against legal challenges
                       regarding erosion setbacks and regulations.)
                   b. properly select, design and locate structures
                   C. calculate beach renourishment intervals.


               3.  Identify the sources of sand feeding the longshore
                   transport system and potential sources of beach fill
                   material.

               4.  Identify and improve our basic understanding of the
                   cause and effect relationships associated with erosional
                   problems.

               5.  Model the impacts of storm events.


         A system  for collecting the data and information required should
          include the following characteristics.

               1.  Historical data (maps, aerial photographs and National
                   Ocean Survey (NOS) T-sheets) should be utilized to
                   document and quantify trends in shoreline position
                   through time.

               2.  A system of monuments to serve as the base line for
                   beach profile surveys should be established at a maximum
                   spacing of one mile along the coast (closer spacing may
                   be required in dynamic areas such as inlets or areas of
                   particular interest). Arrangements should be made to
                   ensure all surveys are done in as short of a time span
                   as possible and, preferably, within a two-week period or
                   less (i.e., as near synoptically as possible). Surveys
                   should be done twice a year (near the time of the
                   maximum summer beach and six months later or near the
                   time of minimum beach widths) and after extreme storm


                                     6









                   ='ients. Profile measurements should extend from
                   landward of the dune (or bluff crest) seaward to a
                   point offshore equal to the closure depth (essentially,
                   the depth at which profile changes are negligible),
                   which was estimated to be at a depth of approximately 50
                   feet MLW on Long Island. Presently, Florida maintains
                   such a system with over 3,400 monuments spaced at 1000
                   foot intervals along its entire shoreline at a cost of
                   approximately $250,000. Experience in Florida,
                   California, South Carolina and other areas where such
                   coastal survey work is presently being done suggests the
                   costs for performing the surveys may range between $1000
                   to $2000 per line per survey. The costs associated with
                   developing and maintaining a coastal survey system are
                   minimal compared to the importance and usefulness of the
                   data obtained through these efforts.

              3.   Aerial photographs should be taken on a seasonal basis
                   (i.e., winter and summer). The overflights should be
                   scheduled for the mornings (before the sea breeze
                   starts) at times between low and mid tide and should, if
                   possible, be coordinated with the surveys described
                   above to provide ground truth measurements. In Florida,
                   the photos are digitized to facilitate their use at a
                   cost of approximately $200 per mile. In addition, these
                   photos are used by the Florida Department of
                   Transportation to develop 2-foot contour maps of the
                   dunes which can be used to estimate storm vulnerability
                   and coastal sediment sources.

              4.   A coastal database should be implemented to compile,
                   maintain, and provide access to the collected physical
                   data as well as information on coastal protective
                   structures, dredging and beach nourishment activities,
                   and other factors described in the following sections.
                   It must be recognized that for this effort to be
                   useful a considerable commitment will be required to
                   maintain the database. However, the potential benefits
                   of such a program should exceed the required effort. In
                   Florida, a database or archive of all coastal data has
                   been established, and it is used extensively by
                   government agencies, planners, consultants, developers
                   and engineers, as well as tax assessors and insurance
                   companies. It is funded as a line item in the state
                   budget.



         Physical ForcingLs Affecting Coastal Change

         The information on coastal features and changes presented in the
         previous section defines and quantifies the effect of erosion
         along the coast. However, the causes of these changes are the
         waves, variations in water levels, and storms that impact the
         coast. Since these are the main physical processes driving


                                    7








          sediment transport which, in turn, determines the coastal
          response, information on these factors is also necessary to
          properly evaluate potential erosion management strategies.

          The information needed on physical forcings include:

               1. statistics on wave height, period, and direction
               2. measurements of the amount of land subsidence and an
                   estimate of the rate of eustatic sea level rise
               3. storm surge heights and frequency.

          Data requirements to obtain this information include:

               1.  local wind (or atmospheric pressure) and nearshore
                   bathymetry data for hindcasting wave climate
               2.  wave gauge records
               3.  tidal records
               4.  long-term water level measurements
               5.  leveling surveys to estimate land subsidence.

          This information would be used to:

               1.  calculate potential longshore sediment transport rates
                   and directions, including frequency and persistence of
                   transport
               2.  estimate the magnitude, impacts and recurrence intervals
                   of storms for cost/benefit and risk analysis
               3.  calculate the perturbation of the sediment budget at
                   inlets to determine sand bypassing requirements
               4.  interpret the causes of shoreline changes in order to
                   predict possible future conditions
               5.  estimate time required for new inlets to close naturally
               6.  develop design criteria for structural and nonstructural
                   responses to erosion control including:

                   a.  lifetime of beach fill projects, which is related to
                       the wave height to the "minus-five-halves" power
                   b.  height, length and spacing of groins
                   c.  spacing, orientation and location of offshore
                       breakwaters
                   d.  material strength requirements.

               7. develop more accurate models to assess and predict
                   impacts of various control alternatives.

          In terms of the physical processes, waves are probably the single
          most important cause or factor affecting erosion in most areas.
          For this reason, information on wave climate is of primary
          importance in developing sound erosion management strategies.
          Although wave data hindcasted from wind records is available for
          the east coast of the U.S., the accuracy of this data is somewhat
          limited (especially in terms of directional information) since it
          was done with a technique that is now 15 years old. To obtain
          the most accurate wave data, the group suggested that two wave
          gauges (one near Montauk and one near the western end of Long


                                      8








          Island) should be maintained over the long term. It was noted
          that Florida maintains 12 gauges around the coast at an
          approximate annual cost of $30,000 each. The U.S. Army Corps of
          Engineers estimates the cost of operating a wave gauge for a year
          at $60,000 and in other areas has entered into cost-sharing
          agreements with local entities to deploy gauges. A 30-year
          hindcast done with the most up-to-date technique would cost about
          as much as maintaining a wave gauge for one year. These
          hindcasts should be calibrated with real wave data from gauges.
          In general, updated hindcasts of wave data would be very useful
          for many purposes, but the development of an effective management
          program would require the installation of permanent wave gauges
          in the future.



          Land Use Patterns and Trends

          A technical evaluation and assessment of any erosion control
          strategy must also consider the uses and activities occurring
          within and adjacent to the project area. Distinctions between
          land uses along the coast must be recognized and incorporated
          into the selection and design process since these factors will,
          in most cases, influence the level of resources to be allocated
          for a project and limit the range of control options available.
          (It would be inappropriate, for instance, to select and evaluate
          a structural approach for erosion control that severely limits
          access to a site that serves primarily as a recreational beach.)

          Data and information needed which relate to land use and the
          development of land use plans include:

              1. identification and location of land use types;

                     a.  housing density and type (year round/seasonal)
                     b.  commercial uses
                     C.  open space
                     d.  intensity and type (e.g., bathing, fishing,
                         surfing, etc.)
                     e.  intensity and type of use at inlets

              2.  description of existing infrastructure
              3.  beach access requirements and associated amenities (i.e.,
                  restrooms, parking, food service, etc.)
              4.  demographics (existing and saturation populations)
              5.  plans for future development or changes in land use.


          This land use information can be used to:

               1.  select and design erosion control
                   alternatives that are compatible with
                   present desired uses and/or accommodate
                   potential future uses
              2.   calculate the economics of the shoreline uses for
                   cost/benefits analysis


                                     9









               3.  evaluate the performance of existing methods of
                   erosion control. Existing structures may be considered
                   as models for estimating the efficiency and
                   impacts of potential future approaches.
               4.  develop and evaluate emergency evacuation plans.


                   APPLICATIONS QF IDENTIFIED INFORMATION   NEEDS


          To provide examples of how the information needs identified
          during the meeting might be used in the decision making processf
          the group was also asked to consider several generic,
          hypothetical situations that typify common coastal erosion
          management issues found-along ocean coasts and briefly discuss
          what they would like to know in order to evaluate and respond to
          these situations. The situations presented involved the
          management of a coastal inlet, the proposed construction of a
          bulkhead on an ocean beach to protect a structure and the
          proposed armoring of the toe of a coastal bluff. A brief summary
          of the major points brought out in these discussions is presented
          below.


          Coastal Inlets

          Because inlets can exert a dominant influence on the processes
          affecting coastal changes, the first situation considered was the
          development of an erosion management strategy related to an
          ocean inlet. Many of the most severe coastal erosion problems
          are the result of the interruption of sand transport patterns at
          inlets and/or poor sand management practices at artificially
          maintained inlets. As a result, most of the discussion on this
          topic focused on the need for sand bypassing.

          It is imperative to make arrangements to provide for the
          bypassing of sand from the updrift to downdrift side of inlets.
          At existing inlets, historical shoreline migration rates showing
          the degree of downdrift recession after the inlet formed could be
          used in conjunction with profile measurements to estimate the
          quantity of sand that would be needed to replace that lost as a
          result of the disruption of the longshore transport by the inlet.
          This information, in conjunction with recent profiling surveys,
          could then be used to evaluate the amount of sand that should be
          artificially bypassed in order to provide the downdrift area with
          a supply of sand equal to that entering the updrift area in the
          vicinity of the inlet. The information on inlet processes
          described in the "Shoreline Processes" section (Appendix D) could
          also be used to refine these estimates by providing a more
          detailed analysis of the specific pathways, sinks, and sources of
          sediment in the area and a better estimate of the amount of sand
          naturally bypassing the inlet (a difficult number to determine).
          The results of this type of analysis could then be used to modify
          bypassing requirements and help identify the most efficient
          techniques for bypassing.



                                     10








         .Ln the case of new inlets, several steps should be taken: a) a
         preliminary estimate of the longshore transport rate should be
         made using wave data and/or the rate of sand impoundment by
         nearby structures; b) this information should be used to develop
         a sand bypassing program (As a general guideline, arrangements
         should be made to begin bypassing sand at a rate equal to at
         least half the estimated net longshore transport rate, however,
         the exact percentage would depend on the particular situation
         and is open to modification based on other information that may
         be available for the site.); c) the downdrift shoreline response
         should be monitored using profiles and aerial photos; and d) the
         amount of bypassing should be adjusted based on the volume
         changes registered by the monitoring program to minimize
         downdrift erosion problems. However, it must be recognized that
         the downdrift shoreline could be influenced by processes other
         than those associated with the inlet, so an attempt must be made
         to discriminate among the different potential causes when
         assessing the results of the monitoring program.

         Bulkhead Construction

         The second situation discussed involved the installation of a
         bulkhead to protect a private home on the open ocean coast
         against storm damage. In response, the participants identified
         a number of questions that should be answered before such a
         project is allowed. For the sake of brevity, we have tried to
         group the related questions into categories (listed below) and,
         where possible and necessary, provide a very brief explanation of
         why these questions were asked (i.e., how the answers would be
         used in the decision making process). Reference is also made to
         the different types of data, previously identified by the group,
         that could be used to answer these questions.

         Basically, six general classes of questions should be answered:

              1.   What is the cause of the erosion problem resulting in
                   the need for the structure? Is there a public works
                   project or other structure updrift exacerbating the
                   problem? Is the structure filling a gap between other
                   structures? Will it advance the line of building? In
                   general, these are management related questions that
                   would be answered by the data described in the land use
                   section. It was noted that if the reason for the
                   structure was the erosion caused by a public works
                   project updrift then special allowances may be
                   considered for the sake of balancing public and private
                   interests. This information could also be used to
                   perhaps identify means of mitigating the updrift cause
                   of erosion, thus, precluding the need for the structure.

              2.   Is the shoreline experiencing long-term retreat? At
                   what rate? When will the shoreline reach the structure?
                   The answers to these questions can be obtained from the
                   analysis of the long-term shoreline trends described in
                   the section on coastal changes. This information allows


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                   one to project the long-term impacts of the proposed
                   action especially in terms of its potential effects on
                   future beach width. If,the shoreline shows chronic
                   landward migration, the stabilization of the back beach
                   area could result in a narrowing of the beach as the
                   shoreline moves landward. If the water line migrates
                   landward of the structure it could have adverse impacts
                   on adjacent properties that may be unacceptable or
                   require mitigative measures. If, on the other hand, the
                   shoreline is relatively stable, the impacts associated
                   with the potential narrowing of the beach over the long
                   term would most likely be minimized or eliminated.

               3.  What is the active beach profile or short-term
                   variability of the beach? How frequently will storms
                   expose the bulkhead, and to what extent will it be
                   exposed? By preventing erosion of the dune or upland
                   during storms, will the structure be depriving the beach
                   and adjacent areas of sand thus aggravating erosion?
                   The information from beach profile surveys, water level
                   measurements, wave observations and studies of the
                   regional geology (sediment grain size distributions)
                   provide the answers to these questions.

                   These answers are important for several reasons. In
                   certain areas, erosion of the upland or the dune
                   (depending on the topography and composition of the
                   material) may provide sand to the adjacent areas through
                   erosion during storms. If this is the case, the
                   bulkhead, by preventing the movement of this material,
                   may cause a local sand deficit equal to the volume of
                   sand that would be lost if the structure was not there.
                   This in turn may adversely affect adjacent areas by
                   depriving them of material they would normally receive
                   during extreme conditions. Where this volume of sand is
                   a significant component of the local sediment budget,
                   the installation of the bulkhead may be conditioned on
                   stipulations that require the owner to mitigate
                   potential adverse impacts by artificially placing a
                   quantity of sand equal to that lost to the system on a
                   yearly basis, as is done in certain situations in
                   Florida. (Florida is developing a technical manual on
                   procedures used to estimate the volume of material
                   required for mitigation measures for shore hardening
                   structures.) Where the dune volume is minimal or upland
                   erosion is not a significant source of suitable sediment
                   (due to volume or composition) these impacts on adjacent
                   areas could be minimal and the project may be warranted.

                   A knowledge of the changes in shoreline configuration
                   (from profile measurements) in response to physical
                   factors (waves and waterlevel variations) could be used
                   to predict how often the structure would be exposed and
                   provide an estimate of the potential impacts on the
                   beach and adjacent areas over time. This information


                                     12








                   could then be employed to develop appropriate set back
                   requirements for locating structures to minimize
                   adverse impacts. Obviously, this type of information
                   would also be beneficial in developing structural design
                   criteria (toe penetration requirements, height, strength
                   of materials, etc.). (A recently-published special
                   issue of the Journal of Coastal Research entitled "The
                   Effects of Sea Walls on the Beach" edited by Kraus and
                   Pilky covers the interaction of shore hardening
                   structures with beach processes and related topics in
                   some detail.)

               4.  What magnitude of a storm is the house (i.e., the
                   structure to be protected) designed to withstand? What
                   is the specific purpose of the structure (to protect the
                   house or dune)? In Florida, if the house is built to
                   100-year flood standards (Federal Flood Insurance
                   requirements), shore hardening is usually not permitted
                   since the house by itself should withstand a major storm
                   without the structure. It was also noted that shore
                   hardening devices generally are not favored for the
                   protection of dunes only and may not be warranted if
                   that is the stated objective.  These structures
                   may be a viable alternative to protect older
                   houses that don't meet present flood standards. In
                   Florida, if the structures are allowed, they are
                   required to be placed as close to the house as possible
                   (usually landward of the dune if there is one) and,
                   depending on the particular situation, may have to
                   incorporate mitigative measures such as toe scour
                   protection. This determination is based on the type of
                   analysis of the site conditions described in Section 3
                   above.

               5.  Will the structure inhibit the recovery or growth of the
                   dune by interrupting the aeolian sediment transport? To
                   accurately assess this impact the information described
                   in "Shoreline Processes" section (Appendix D) under dune
                   formation and aeolian processes as would be needed and
                   could be used to help determine if the proposed action
                   would adversely affect dune building processes and to
                   what extent, what structural changes might be made to
                   ameliorate the condition and whether artificial dune
                   restoration would be necessary and what level of effort
                   would be appropriate.

               6.  What is the local and neighboring land use? commercial
                   or residential? What are the uses of the beach and who
                   needs access (fishermen, bathers, etc.)? Will the
                   structure inhibit the access or use? This information
                   relates both to the land use data and the potential
                   changes in the beach mentioned in 2 and 3 above. It
                   would be used to determine if the structure would
                   significantly change the configuration of the beach (in
                   terms of beach width, for example) and, if so, the


                                     13








                   relative impact of the changes on the present use. It
                   could also be used to help identify potential mitigative
                   the construction of right-of-ways or cross-overs.

          Although the situation considered here involved the installation
          of a specific type of shoreline hardening device (a bulkhead), in
          general, the type of questions asked and the information needed to
          answer these questions would also be required to evaluate the
          other types of shore hardening devices commonly used in coastal
          areas.


          Armoring of Coastal Bluffs

          The last situation considered was the proposed armoring of the
          toe of a coastal bluff with a revetment to protect an individual
          upland structure. Because there are a number of similarities
          between this type of project and the previously described
          situation involving bulkheading, many of the same considerations
          would be applicable. In particular, the information related
          to categories 1, 2, 3 and 6 above, would be pertinent. However,
          there are also some fundamental differences between the two
          situations that require additional considerations and
          information. Among the more important differences noted were the
          following: 1) unlike the dunes, bluffs are a relic feature and
          cannot be expected to recover after an erosional event, 2) the
          erosion of bluffs may have a more important role in the sediment
          budget (depending on their size and composition) than the role of
          dune erosion, and 3) the erosion processes on bluffed coasts may
          be significantly different than those occurring along other parts
          of the shore.

          In addition to the questions and information described in the
          discussion on the bulkhead, the following types of questions
          should be considered in assessing a proposal to armor the toe of
          a bluff:

               1.  Is the structure addressing the primary cause of
                   erosion? In many cases, other factors such as
                   groundwater may be a more dominant cause of erosion than
                   undercutting at the toe in bluffed areas. Although a
                   geotechnical analysis would be required to make a full
                   analysis of the exact processes causing the erosion and
                   their relative magnitude, some measure of the importance
                   of undercutting may be obtained by examining profiles
                   and aerial photographs. Recession of the toe over the
                   long term or the presence of scarps at the base of the
                   bluff after storms would tend to indicate wave
                   undercutting is occurring and some type of toe
                   protection might be necessary to slow down the erosion.
                   If processes acting within or on the bluff face are the
                   cause of the erosion, coastal engineering structures at
                   the toe would have little effect. This analysis could
                   also help identify possible factors such as lawn
                   watering, septic leakage, etc. which may be exacerbating
                   the problem and could be rectified relatively easily.


                                     14









               2.  What is the rate of erosion and the height of the bluff?
                   What is the composition of the material? How rapidly is
                   material eroded from the bluff removed from the beach?
                   Information from profiles, historic recession rates and
                   data on regional geology described in the section on
                   coastal changes (page 5) along with the data identified
                   in the "Shoreline Processes" section (Appendix D) under
                   bluff erosion would be required to answer these
                   questions. This information and data could be used to
                   determine if the bluff is indeed supplying the type of
                   material needed to maintain the beach and longshore
                   transport sediment transport system and, if so, at what
                   rate. If the erosion of the bluff is not supplying a
                   significant source of the type of material found along
                   the downdrift beaches or in sediment transport system
                   because of the composition (i.e., the material is too
                   fine or the material is too large to be moved by the
                   processes acting in an area) or the volume eroded (due
                   to a low recession rate or the height of the bluff) then
                   these impacts would probably be minimal and the project
                   may be justified. However, if the erosion bluff is a
                   significant source of beach-sized material the proposed
                   armoring may have adverse impacts on surrounding areas.
                   This information could also be used to develop
                   mitigative measures such as requiring the applicant to
                   supply a quantity of beach compatible material from an
                   upland equal to the volume lost due to the armoring.

               3.  Could the structure to be protected be relocated or
                   setbacks established to preclude the need for the
                   structure? Information on the bluff composition,
                   profile (height) and lot size would be required to
                   determine a prudent setback and whether relocation is
                   'feasible.

               4.  Where along the bluff does the erosion occur? Does the
                   beach have to be eroded before the bluff is attacked?
                   This information could be obtained from post- storm
                   surveys and/or aerial photographs, wave and waterlevel
                   data, and data on regional geology. It was pointed out
                   that in some areas of California, the erosion of bluffs
                   during storms often occurs at a point below the
                   elevation of the beach after the beach has been removed
                   by the waves. If this does happen in an area, armoring
                   of the toe of the bluff above the elevation of the
                   active beach profile, as is often proposed, would
                   provide little benefit, and special consideration would
                   have to be given to the design of the structure in terms
                   of required depth of penetration.







                                     15









                                       APPENDIX A



                                     LIST OF ATTENDEES



               Henry J. Bokuniewicz               Marine Sciences Research Center
                                                  State University of New York
                                                  Stony Brook, NY 11790-5000
                                                  516-632-8674
               Robert G. Dean*                    Dept. of Coastal and
                                                  oceanographic Engineering
                                                  336 Weil Hall
                                                  University of Florida
                                                  Gainesville, FL 32611
                                                  904-392-2416
               Craig Everts*                      Moffatt and Nichol, Engineers
                                                  250 W. Wardlow Road
                                                  Long Beach, CA 90807
                                                  213-426-9551
               Nicholas C. Kraus*                 Waterways Experiment Station
                                                  Coastal Engineering
                                                  Research Center
                                                  P.O. Box 631 (WESCR)
                                                  Vicksburg, MS 39181-0631
                                                  601-634-2018
               Choule J. Sonu*                    Tekmarinef Inc.
                                                  572 East Green St.
                                                  Pasadena, CA 91101
                                                  818-405-91111


               Jay Tanski                         New York Sea Grant Extension
                                                  143 Dutchess Hall
                                                  State University of New York
                                                  Stony Brook, NY 11790-5001
                                                  516-632-8730

               Ron Verbarg                        Long Island Regional
               Mike Volpe                         Planning Board
                                                  12th Floor
                                                  H. Lee Dennison Building
                                                  Veterans Memorial Highway
                                                  Hauppauge, NY 11788
                                                  516-360-5200


                  Indicates invited participant







                                      16







                                  APPENDIX B

                           IN T E. -'C,'@ P R O'G F A %1











         JJT73189                                 9 February 1989






         Dr. Robert Dean                          Dr. Craig Everts
         Department of Coastal and                Moffatt and Nichol Engineers
           Oceanographic Engineering              250 West Wardlow Road
         336 Weil Hall                            P. 0. Box 7707
         University of Florida                    Long Beach, California 90807
         Gainesville, Florida

         Dr. Choule Sonu                          Dr. Nick Kraus
         Tekmarine, Inc.                          USAE Waterways Experiment Sta.
         572 East Green Street                    Coastal Eng. Res. Center
         Pasadena, California 94549               Research Division (WESCR)
                                                  P. 0. Box 631
                                                  Vicksburg, Mississippi
                                                       39180-0631


         Gentlemen:

         The first workshop on Long Island's south shore erosion problems
         and management alternatives is scheduled to start at 1:00 PM Friday
         February 24 at the Tampa Hyatt Regency. We are writing to provide
         you with a little more information on how we foresee the format of
         the meeting and to solicit any comments or suggestions you may
         have.

         As you know from previous conversations, the purpose of this
         particular meeting is to more clearly define the type of technical
         information and physical data that are necessary to make rational,
         informed decisions regarding the selection of the most appropriate
         erosion control strategy for a coastal region. In other words, if
         you were asked to make a recommendation concerning the type of
         erosion control that is best for a certain ocean coastal region,
         what questions would you need answered and how will the answers
         affect your decision?


                                       continued







                                        17







                                  APPENDIX B






                                         - 2


         One of the first questions might be "what are the objectives of the
         management plan?" Although this workshop is primarily concerned
         with identifying the more technical informational needs, the
         process used to make a preliminary evaluation of the feasibility of
         any erosion control alternative also depends on the desired
         objectives of the project. These objectives are often decided on
         the basis of socio-economic factors rather than technical criteria.
         While these socio-economic factors must be considered in planning,
         an in-depth treatment of the associated issues is well beyond the
         scope of this meeting.

         So, after much deliberation, we thought the most efficient way to
         focus our discussions would be to have the group consider a
         generic, hypothetical shoreline situation and a general set of
         objectives that the selected erosion control option should achieve.
         For the purposes of discussion, we will assume that the managers
         have  the following objectives:

               1.  Maintain the recreational beaches
               2.  Hold the shoreline position in urban areas
               3.  Maintain and stabilize existing inlets
               4.  Prevent new inlets from forming
               5.  Maintain existing dune formations
               6.  Prevent back-beach flooding
               7.  Prevent adverse downdrift effects due to the method
                   employed in any area.

         If you were approached to recommend an erosion control strategy,
         what would be the first questions you would ask? We expect the
         information you might want would include some of the items
         listed on the attached page. Although the situation described is
         somewhat vague, it is probably similar to some of those you have
         actually encountered in your work.

         We hope that you can find some time before the meeting to give some
         thought as to the process you would use and the specific type of
         technical information you would require to make a preliminary
         determination of which erosion control alternative(s) would be most
         promising.

         As you think about developing your list, we would like you to
         consider to the following points.-



                                     - continued









                                         10







                                  APPENDIX B







                                           3


               1.  To the extent possible, we want to concentrate
                   on technical information needs.

               2.  We are trying to identify the most suitable or
                   appropiate strategy in a general sense, rather than
                   trying to design a specific structure for a particular
                   area. In a particular situation, which option (e.g.,
                   bulkheads, nourishment, groins, etc.) is most likely to
                   warrant the effort needed to explore a detail design?

               3.  We are interested in knowing how a particular piece of
                   information might be used in the decisionmaking process
                   and identifying the minimum amount of information
                   necessary.

               4.  What form or format should the information be in to
                   facilitate its use.


         When we meet in Tampa, we hope that each of you would discuss the
         physical information you need identified and briefly touch on how
         that information would be used. Based on these preliminary
         dicussions the group would then focus on how changes in the
         objectives of an erosion control plan might affect the type of
         information required.

         By the end of the second day, we hope to produce a comprehensive
         list of the type and amount of technical information and physical
         data that is needed to make an informed decision on the most
         suitable erosion control strategy for an area given a range of
         possible objectives. This list will then serve as a basis for the
         second workshop which will concentrate on determining on what data
         is available for the south shore of Long Island and identifying
         informational gaps.

         So far, that is our agenda. We would appreciate hearing any
         comments, suggestions and/or criticisms you may have. Also, if you
         have any questions or would like additional information regarding
         either the content or logistics of the meeting please don't
         hesitate to contact us (Henry (516) 632-8674; Jay (516) 632-8730.

         We look forward to seeing you in Florida.

                                      Sincerely,



            Henry Bokuniewicz                         Jay Tanski

         HB:JJT/mj







                                 APPENDIX B







                        POTENTIAL TECHNICAL INFORMATION NEEDS

         While by no means complete, the following is an example of some of
         the types of physical and technical information that may be
         required to make a preliminary determination of the most
         appropriate methods for controlling erosion in an area.



         1. Shoreline Type (barrier island, headland, etc.)

         2. Historical Shoreline Trends

                   -long-term recession/accretion rates
                   -short-term recession/accretion rates

         3. Shoreface Form and Variability

                   -beach/dune topography
                   -equillibrium/storm profiles
                   -seasonal profile variations
                   -shoreface volume changes
                   -depth of profile closure
                   -offshore bar location/size/variability

         4. Sediments

                   -grain size composition/variability
                   -sediment transport rates, volumes, directions
                   -sediment sources/sinks

         5. Long-term and Extremal Sea Conditions

                   -tidal range
                   -magnitude and recurrance intervals of storm surges
                   -long-term average wave climate (height, frequency,
                    direction)
                   -extremal wave climate (height, frequency, direction)

         6. Type, location, and effects of man-made structures

         7. Location and sediment dynamics of existing inlets.








                                         APPENDIX C




                   First Workshop on Long Island's South Shore Erosion Problems
                                February 24-25, 1989, Tampa, Florida


          Discussion contribution from N. C. Kraus listing basic data required for
          shoreline change modeling for evaluation of alternative shore protection
          designs. (excerpted from Hanson, H., and N. C. Kraus, 1989, Technical Report
          CERC-89--, -GENESIS: Generalized Model for Simula:ting Shoreline Change,"
          Report 1, Reference Manual, U.S. Army Engineer Waterways Experiment Station,
          Coastal Engineering Research Center, Vicksburg, Miss., in prep.)

                                               Table 4
                            Data Reguired for Shoreline Change Modeling


              Type of Data                               Comments

          Shoreline position       Determination of the shoreline trend. Shoreline
                                   position at regularly spaced intervals alongshore by
                                   which the historic trend of beach change can be
                                   determined.


          Offshore waves           Time series or statistical summaries of offshore wave
                                   height, period, and direction.

          Bathymetry               Bathymetry for transforming offshore wave data to
                                   values in the nearshore at regularly spaced interval
                                   alongshore.

          Structures and           Location, configuration, and construction schedule of
          other engineering        structures (groins, jetties, detached breakwaters,
          activities               breakwaters, seawalls, etc.). Porosity, reflection,
                                   and transmission characteristics, as appropriate.
                                   Location, volume, and schedule of beach fills,
                                   dredging, and sand mining.

          Regional transport       Sediment budget for the area; identification of
                                   littoral cells; location and functioning of inlets;
                                   discharges from rivers; wind and wind-blown sand.

          Regional geology         Sources and sinks of sediment; grain size distribu-
                                   tion; regional trends in shoreline movement; subsi-
                                   dence; sea level change.

          Tide                     Tidal range; tidal datum.

          Extreme events           Large storms (waves, surge, beach erosion, failure of
                                   structures, etc.); inlet migration, opening, or
                                   closing; river discharges; earthquakes.

          Other                    Wave shadowing by large land masses; strong coastal
                                   currents, such as the Gulf Stream; etc.







                                                  21












                                       APPENDIX D



          Shoreline Processes

          The information and data needs presented in the body of this
          report represent the most basic or fundamental technical knowledge
          required to begin developing a sound coastal erosion management
          plan. Collectively, they can provide a basis for decision
          making. However, the certainty with which erosion risks can be
          estimated and the impacts of proposed actions can be predicted
          depends not only on the availability of site-specific data but
          also on a basic understanding of the interaction and effects of
          the complex and variable coastal processes operating along the shore.
          An effective, comprehensive plan must also incorporate the most
          up-to-date knowledge of the processes involved. For this reason,
          any proposed management plan should also include provisions for
          utilizing the acquired physical data to assess and quantify the
          phenomena affecting shoreline changes. of particular importance
          are those processes influencing sediment dynamics and regional and
          local sand budgets, some of which are listed below. A proper
          evaluation of these topical areas requires a skillful
          interpretation and analysis of the type of data described
          previously. More rigorous investigations of the following
          phenomena associated with the transport of sediment will often be
          critical in adequately assessing proposed erosion management
          alternatives in certain areas.


               Longshore sediment transport

                 Data needed:
                    a.  shoreline orientation
                    b.  wave statistics
                    C.  location, volume, size characteristics of sand
                        deposits (sources)
                    d.  sand trapping rates at structure.

                  Uses:
                    a.  identify and minimize impediments to the
                        longshore sand supply
                    b.  characterize reversals in the transport
                    C.  calculate the lifetime of nourishment projects
                    d.  estimate sand by-passing needs around structures and
                        inlets
                    e.  evaluate the performance of existing
                        structures
                    f.  estimate the rate of inlet shoaling or
                        closure.










                                       22








              Cross-shore sediment transport (including seasonal cycles,
              storm effects and long'-term flux)

                Data needed:
                    a.  sequential bathymetric profiles
                    b.  wave and current data
                    C.  sediment grain size and distribution

                Uses:
                    a.  calculate the impact of extreme events on
                        the sediment budget
                    b.  estimate the rate of recovery after storm
                        erosion
                    C.  siting of structure such as breakwaters or
                        groins whose relation to the bar is
                        important
                    d.  identify sources or sinks of sand for the
                        beaches.


              Inlet processes

                Data needed:
                    a.  history of occurrence and migration rate
                        from charts and aerial photographs
                    b.  volume and rate of growth of ebb and flood
                        tidal deltas
                    C.  wave refraction in the vicinity of inlets
                    d.  tidal prism and cross-sectional areas
                    e.  current patterns and velocities.-


                Uses:
                    a.  evaluate potential sources of sand for
                        renourishment and identify offshore sand sinks
                    b.  decide on the need to artificially close
                        or stabilize new inlets
                    c.  estimate the amount and frequency of sand
                        by-passing required at inlets
                    d.  examine the hydraulic interaction of
                        multiple inlets
                    e.  evaluate role in barrier island migration
                        processes.

              Dune formation and aeolian processes

                Data needed:
                    a.  geomorphology (size, composition, form) of
                        existing dunes including vegetation
                    b.  meteorological data (precipitation,
                        evaporation, local winds)
                    c.  beach conditions (grain size, berm
                        elevation, tides).

                Uses:
                    a.  quantify role of dunes in the sediment budget
                    b.  calculate the amount of wind-driven sand



                                       23







                        supplied to inlets (shoals are sometimes
                        formed by wind-driven sand in inlets)
                    C.  evaluate feasibility and need for dune
                        reconstruction or renourishment for erosion and
                        flood protection
                    d.  estimate impact of structures or other actions on
                        dune building processes.

               Bluff erosion


                 Data needed:
                    a.  heights and recession rates
                    b.  composition
                    c.  groundwater seepage
                    d.  frequency of collapse.

                 Uses:
                    a.  estimate the role of bluff erosion in
                        supplying sand for longshore transport
                    b.  assessing the effectiveness of armoring
                        the bluff toe to prevent erosion (if
                        groundwater seepage is the dominant
                        erosive mechanism other protective
                        measures, such as drainage systems might
                        be needed.)

               Morphodynamics (the identification of bars,
               shoals, shore-connected ridges, ebb/flood tidal deltas
               rhythmic beach features, etc. and associated processes)

                 Data needed:
                    a.  aerial photographs and sequential
                        bathymetric records
                    b.  grain size distribution.
                    C.  wave and current climate


                 Uses:
                    a.  evaluate their role as sediment reservoirs
                        in the coastal sand budget or conduits for
                        sand transport
                    b.  calculate rate of transport around inlets.

               Overwash processes


                 Data needed:
                    a.  distribution and morphology of former
                        overwash platforms
                    b.  volume of sand moved in overwash events.


                 Uses:
                    a.  calculate the amount of sand removed by






                                       24








                   b. estimate the rate at which platforms are
                       provided for marshes
                   C. identify and quantify role in barrier island
                       migration.






















































                                                                of Commerce
                                                  us Department        r L" rarY
                                              NOAA Coastal Services centc
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