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Coastal Zone Information Center COASTAL EROSION control handbook for ... Rhode Island COASTAL ZONE INFORMATION CENTER TC 224 .R4 N48 1981 COASTAL ER OSION control handbook for... Rhode Island written edited illustrated designed ... Arthur J. Neumann Prepared for the Rhode Island Coastal Resources Management Council May 1981 'CREDITS Credit is given to the Landscape Architecture Department at the Rhode Island School of Design, for helping to develop the skills necessary for the preparation of this project. As a faculty advisor, Michael Everett has offered guidance and criticism that has led to the format of this project. Lee Whitaker, of theDivision of Coastal Resources, has provi-- ded his knowledge of Coastal Zone Management and has lent support throughout this project. Donald Greenough and Mtcholas Pisani, have, in part, allowed the field work to be possible, and have provided their suggestions and knowledge of Engineering. Other persons within the Coastal Resources office have generously provided their assistance and use of office facil- ities for the preparation of this project. Linda Steere and James Parkhurst, Biologists for the Division of Fish and Wildlife, have shared their knowledge. Special attention is given to the outstanding efforts that Donald Greenough, James Parkhurst, Nicholas Pisani, and Linda Steere have afforded in support of Coastal Conservation and Restoration. CONTENrrs PREFACE I Planting 21 PROBLEM 2 Soll, Preparation 24 SOLUTION 3 Ground cover planting 24 METHOD 3 Mulches 25 NON-STRUCTURAL CRITERIA 4 Shrub planting 26 AESTHETIC CRITERIA 5 Tree planting 26 STORM EROSION .. RHODE ISLAND 7 NATURAL ENVIRONMENT SHORELINE ECOSYSTEMS Geology 9 COASTAI, WETIANDS 30 Hydrology 10 Natural Inventory R.I. Coastline 10 Physiography.. Geology 31 Tides & Winds 12 Soils 35 Waves 13 Hydrology 35 Currents & Surges 14 Vegetation 35 Littoral Transport 15 Biotic Community 38 Natural Stabilizers 15 Aesthetic Environment 39 ECOSYSTEM MANAGEMENT 17 Existing .. Proposed Solutions. 41 VEGETATION .. EROSION ABATEMENT 18 Salt Marsh Establishment 48 Selection 19 Shore Erosion Abatement 48 Delivery 20 Site Suitabilities 49 Site Preparation 21 Site Preparation 51 Planting 51 BEACHE S 80 Factors Limiting Establishment 53 Natural Inventory Maintenance 54 Physiography.. Geology 80 Soils 83 BARRIER BEACHES 55 ilydrology 86 at@ral Inventory Vegetation 86 Physiography.. Geology 56 Biotic Coitnaunity 87 Soils 61 Aesthetic Environment 89 Hydrology 61 Existing .. Proposed Solutions 90 Vegetation 63 SITE SPECIFIC -DESIGN 98 Biotic Community 64 COASTAL VEGETATION 103 Aesthetic Environment 66 Coastal Wetlands/Beaches Existing .. Proposed Solutions 68 Ground cover 104 Beach Grass Establishment 76 Shrubs 105 Procurement 76 Trees 107 Arrangement 76 Barrier Beaches 108 Planting 77 REFERENCES 110 Fertilization 78 ILLUSTRATIONS PREFACE The State of Rhode Island's Coastal Resources Management Council's (CRMC) gulding principal is to "preserve, protect, develop, and where possible restore coastal ecological systems, and to measure, judge, and regulate any environmental alteration of the coastal resources.01 Since ecological systems are the basic functional units of nature, it is nec- essary to design plans and programs for the protection of each resource. Tile adopted policies and regulations of the CRMC state that the Council shall. favor non-structural- erosion controls. The intention of this publication is to evaluate and provide au understanding of Rhode Island's coastal systems, determine past and present impacts of structural- erosion controls, and to provide a range of options for the use of non-structural erosion controls that will best simulate natural processes and reduce impacts to the coastal. zone. The premise of this handbook is that structural erosion controls generally are visually and physically degrading to ecologically and environmentally important coastal systems locally and wl.thin a broader scale. The overriding design goal is to make erosion control measures visually and physically subordinate within the coastal zone landscape. There are erosion conditions along isolated sections of the Rhode Island shoreline where non-structual controls are not wholly appropriate nor effective. In such cases, structural controls must be designed for site specific conditions and evaluated by the CRMC and its staff to ensure that the proposed structure will effectively c-ontrol the erosion without causing adverse impacts on adjoining and nearby shoreline property or the environment. THE PROBLEM It has been proven that wind, water, and gravity are the primary factors that encourage erosion with- in coastal areas.. The rate varies according to the slope, soil composition, vegetative cover, meteorolog- ical conditions, and wave and current velocities. It is a fact that within these coastal areas property is threatened by erosion, and people invariably consider structural solutions. People do so without realizing non-structural methods'are less expensive, and in the long run, more effective buth physically and visual- ly In Rhode Island human activity close to the shoreline will weaken Its' capacity to withstand erosion- al forces. In certain cases where people clear house lots along the coast, the loss of vegetation intenst- fies the velocity and rate of fresh water runoff, causing the erosion and sedimentation to the shoreline and adjacent area, and a loss of property will result. Another example can be seen along the beach where a jetty has been constructed. Here sand accumulates and restores the immediate area although, the down- drift zone has been deprived. Therefore, cummulative effects should be considered before any alteration to the coastal gone has been initiated. All shoreline systems are dynamic and change their shape and character in response to storms, cur@ rents, unnecessary human modifications, and the gradual rise in sea level, therefore, these are unstable sites for permanent structures. CRHC field experience has demonstrated that a portion of the public sector is not aware of the fact that any alteration to the coastline could impact upon that area. The people that should be totally aware of this (i.e.,homeowners,contractors,and developers) are not and often times fall to file an'appli- cation with the CRMC for shoreline alteration. Normally, if non-structural methods of erosion abatement are used the owner can begin work with a letter of assent from the Council instead of having to go through the application procedure. Failure to receive CRMC approval prior to commencement of shoreline alteration work or the installation of shoreline protection facilities will result in delays, possibly legal action, and otherwise avoidable problems had the party correctly sought Council approval. It is the' intention of this handbook to inform the public of shoreline treatments most acceptable to the state, based on existing natural conditions, 2 SOLUTION In 1972, the Coastal Zone Management Act was passed by the federal government because of an awareness for potentially adverse effects of intense pressures upon the national coastal zone. It Is on the state level of government that specific policies and regulations have been designed to manage the coastal zone (illus.1). Theoretically the planning and management processes continue to evolve from basic standards and criteria. Concurrently, the-Science Of Ecological Planni-nS and' the Art Of Landscape Architecture will be used to evaluate and design solutions for non-structural erosion controls. The Ecological PlannIng Process will establish a framework that is broad enough to study entire ecosystems as well as examine individual environments within that ecosystem. METHOD TUE SCIENCE OF ECOLOGICAL PLANNING Involves two stages: 1. Inventory of natural and cqltural conditions. 2. Synthesis of natural and cultural conditions. THE ART OF LANDSCAPE ARCHITECTURE Includes: 1. Evaluation of aesthetic environment based on aesthetic criteria. 2. Selection and !adaptation of preferred design solutions. The preferred design solutions are based on the idea of ecosystem management and are clearly-cognizant of cultural needs. 3 NON STRUCTURAL CRITERIA A survey of Narragansett Bays' shoreline in 1979, revealed that along a quarter of the shoreline natural features had been replaced by man-made structures. Most of the construction on the shoreline that has taken place in the last t1jo decades is an attempt at "erosion prevention", undertaken at great cost by private owners. Unfortwately, many of the people who have built bulkheads or rip-rapped their shore- front with fitted stone or concrete do not realize that most of the erosion In the Bay takes place during major storms and hurricanes and that their structures will not withstand even a "ten year storm" of high intensity. These same structures, however, are usually.more elaborate than what Is necessary to check the small scale erosion that takes place between major storms (1). Vegetation as a means of erosion abatement is more efficient than structural methods and is by far less.expensive. If a comparitive cost analysis was done for constructing a bulkhead or rip-rapping as opposed to planting and maintaining vegetation the results would be totally in favor of planting vegetation. While doing so, the cost of reconstruction after a major storm should be kept in mind. Not only is the use of vegetation as a means for erosion control less expensive, but it also provides for wildlife needs. With the proper selection of plant species, food, shelter, and breeding habitats can be provided for local species. 4 AESTHETIC CRITERIA "AESTIIETICS" is defined as a branch of philosophy concerned with that which Is beautiful in art and na ture. The aesthetic quality of Rhode Island's coastal systems is based on and characterized by landform, water, and vegetation. Each coastal system offers uILLqug variety and vividness. Variety Is seen and vivid- ness is perceived as a strong, clear impression on the senses. Variety and vividness Is derived from terrain patterns, presence of water, weather characteristics, vegetational pattern, and cultural land use patterns. Uniqueness Is determined by the composition of space, form, texture, and color of any given coastal unit. Since coastal systems are considered aesthetic resources they are visual or sensory attributes of a landscape, and have a value distinct from that of the practical utility of ecological functions of the resource. The protection of aesthetic resources. along the coastline, would reinforce the wise management of biological and ecological resources, and would maintain and enhance the visual ad perceptive qualities that these resources provide. Management of the environment for its aesthetic aad ecological attributes is a valid concern I-or everyone. Any physically placed cultural influence prevalent within a, or along a coastal system forms a basis for aesthetic judgement. Cultural influences alter the unIque quality, and uniLy of a particular landscape unit. Unity alteration is degrading to Rhode Island's coastal landscape. 5 41 7V- STORM EROSION R.I. EFITM I I zz"41 41 00 im al-@ iN!n j Ne Aai M"A @c 4", Ilk fr- -4 f. NATURAL ENVIRONMENT GEOLOGY Approximately 12,000 yrs. ago during the last ice age, in the Tertiary and Pleistocene Periods, R.I. was a series of hills and valleys with rivers flowing toward a sea whose shore lay off what is now Block Island. As the glacier moved southward, it covered the land with ice as much as a mile thick, scouring and scraping the land to create the gentle contours characteristic to the R.I. landscape. As the glacier re- treated, vast quaptities of boulders, sands, and sediments where deposited over the land and Into the river valley that now underlies Narragansett Bay (2). A large variety of shoreline types can be found along the coastal edge of Rhode Island. Sandy barrier beaches can be found along the southern shorelines. These landforms act as natural buffers that protect the coastal wetlands directly- inland. This southwestern shoreline is generally composed of glacial. outwash. (illus.2). 2. 3. Along the southeastern coastline starting in Newport, large cliffs of bedrock prevail formIng a Jagged shoreline, and in places sandy beaches have formed from eroded bedrock and other sediments. East along Little Compton, and in Tiverton, easily erodeable shorelines of glacial till exist (illus.3). Wide sandy beaches are found along the ocean shore at Bonnet Shores, and between the southern headlands of Middle- town. There are a few sandy beaches Inside Narragansett Bay where longshore currents have built small barrier spits across shallow embayments and cu8pate beaches such as Conimicut Point. The most common shoreline in the state is a narrow shoreline of till backed by a scarp. The scarp is often unvegetated. The shorelines of Beavertall and Common Fence Point are made of soft rock that is easily erodible. Brenton Pt., Is made of a hard granite and metaniorphic rock that is by far the most resistant to erosion. Another category of shoreiine is common in sheltered waters, where sediments are likely to accumulate. Here salt marshes flourish. If undisturbed salt marshes are capable of laying down a layer of peat, composed of 9 dead plant material, that permits the living marsh to grow upward and keep pace with the ri sing sea level. In some old and well-established marshes, the peat may be several feet thick. HYDROLOGY Glaciers have dramatic effects on sea level. When New England's surface water was in the form of ice, the oceans were much smaller. During the last glacier, the Wisconson, sea level in this region was about 300 ft. lower than it is today. As the ice melted sea level rose and advanced inland. The rise due to both a slow increase in the volume of water in the ocean and to a gradual sinking In the New England land mass. The present rate of rise in sea level may seem insignificant, but it should be kept in mind that much of the shoreline is low-lying and that a vertical rise of 1 ft. may account for an inland advance of thirty or more feet. Rainfall In R.I. averages 3 ft. per yr., and river discharge peaks in March and April. With the in- creasing development of paved upland surfaces discharge into rivers and streams is greatly accelerated and can contribute to the rise in sea level. Some scientists conclude that the increase in carbon dioxide in the worlds' atmosphere caused by the rapid burning of fossil fuels in this century may cause a warming trend. This could melt more ice at the poles and rapidly accelerate the rise in sea level worldwide. Others argue that the carbon dioxide levels are not great enough, or it may only serve to forestall the period of climatic cooling that wil preclude the next era of glaciation (3). RHODE ISLAND COASTLINE The Rhode Island coastline, like others, Is never still. To the casual observer this seems obvious since the water conditions are ever changing. Tide and waves, storm and calm are the dynamics that can go unnoticed. But there are other actions revealed to a slightly more perceptive observer. Certainly, this does not make the coast different in kind from all other places on earth, but the rate of change is always faster. Since the coastal zone is only a narrow band at the junction of land and sea, it makes the rela- tive importance of change a serious matter, not only to man, but to the survival of the intricate and pro- ductive systems of plants and animals that are found there. Like man, these organisms have continuously adapted to the coastal dynamics. The balance between the organized biological arrangements and the chang- ing face of the coast are often delicate when seen against the extremes of energy released through sotrms, sweeping ocean currents, and large tidal increases. To better appreciate the conditions of coastal existence, It to helpful to think of tile coast as the meeting and mixing place where fundamental forces and substances from both land and sea are joined. Every day of every year materials are blown or washed from the land's surface and carried down to tile water's edge. Tile constant renewal of tile meteorological and hydrological systems powered by solar energy and gra- vitattonal forces guarantee the transport of the earths' materials to the oceans will continue. Contained in the flows of waters and winds are sands, silts, clays, and organic particles along with dissolved chem- Ical compounds from tile land. These substances may accumulate in higher concentrations as they are trans- ported to coastal waters thus increasing the load for eventual deposition to the oceans. Title land to sea movement contributes basic material for the building of coastal forms, and Is the source of salts and chemical nutrients necessary to tile health of coastal and o4@eanic ecosystems. Unfortunately, not 611 materials transported from land to coastal. waters are benign and beneficial. The same forces that carry chemical nutrients such as nitrogen, phosphorous, calcium, iron, potassium, aiid others also move tile waste products of human endeavor to the coast. These waste substances are often harm- ful either because they are over-concentrations of otherwise useful and needed materials or because they are directly toxic to living things. When tile land-derived materials enter the coastal areas, the currents, tides, and waves of the coastal waters provide the transport system for distribution and dilution. This action of transport from places of origin or concentration to places richly endowed with nutrients and food sources spreads the chemical basis for biological productivity along tile coastal zone and outward to the ocean. River outfalls, coastal wetlands, and estuaries are singularly important areas for which nutrients and food are removed. Many of the currents transporting materials from the outfalle carry them long dis- tances. Less dramatic, but equally Important are the local currents and daily tides (tllua.4). VAMP-b 4. in many ways, it Is tile effects of day-to-day stresses of w1nds. waves,tides, and currents rather than maJor storms that are tile physical factors which determine the biologic systems occupying different loca- tions along the coast and from coast to open sea. It is the high and low levels of tide that determine the zonation of plant and animal species on all shores. It is the depth of disturbance of waves coupled with turbidity that limits the growth of subtidal organisms on the floor of the sea. It Is the shape and compo- sition of the water's floor, In combination with coastal currents and tides that influence species of fish in their choice of habitats. It is the patterns of flow, the circulations, and mixing of fresh and saline waters in tile estuaries : and coastal ponds, that fix tile locations of shellfish beds or the spawning areas of other mollusks (clams and scallops), crustaceans (crabs and lobsters), and fish. And it Is the transport and dilution of both benificial. and harmful chemicals and sediments by coastal and ocean ctir@ rents that in large part determine tile level of productivity of coastal ecosystems,O). The dynamics of a coastal area are therefore, essential to Its' ecological well-being. 'rIDES & WIND Tile forces of the sea originate in tile sun and tile moon. The sun causes air movements, winds, and hel.ps the moon create the tidal rise and fall of tile ocean surface. Air movements originate with tempera- ture changes. The still heats the earth, the waters of tile earth, and the air around tile earth, but this heating Is not uniform. The air In some parts of the earth Is heated more than that in other places. The warmer, lighter air rises, causing a zone of reduced pressure; winds result as colder, denser air moves into this zone (5). The moon and to a lesser extent theisun, creates the tides of tile sea. During full moon days and twb days thereafter the,tide averages its highest provided there is no meteorologic influences. This is al.so true during new moon periods. This tide level is referred to as "Mean High Water Spring",MHWS. On other days tile highest limit line is, M11W. The low tide limits are just the opposite with "Mean Low Water Spring", MLWS, and MLW. The mean tide level is genetally that of mean sea level. In Rhode Island tidal fluctuations vary from a height of 3.6 ft. at the southern portions of the state, where the Narragansett Bay and the Sakonnet Rivers meet the ocean, to 4.6 in the upper, northern, zones of these areas. Although, when high energy storms are present the water level can exceed the height of all average high tide in places by 10-12 feet (1). Together, the sun and moon generate tile tides because they attract the water masses in tile same way that the earth attracts objects near its surface. Because of this gravitational force and the fact that the sunt moon, and earth are always in motion with relation to each other, tile waters of the ocean basins are set in motion. Once the water masses of the oceans have been set in motion, they create the tides and currents (5). WAVES The familiar waves of the sea are "wind waves" generated by winds blowing over the water. They may vary in size from ripples on a coastal pond to large ocean waves. Wind waves cause most of the damage to shorelines. Another type of wave, the tsunsmi, is created by earthquakes or other large disturbances on the ocean bottom, but fortunately they do not occur frequently along the Rhode Island coastline. Wind waves, known as oscillatory waves, are usually defined by height, lenght, and period (illus. 5). Wave period is the time between successive crests passing over a given point. WAVE CHARACTERISTICS 5. When waves move over the water, only the form and energy of the waves move forward. Advance of the wave form causes oscillatory motions of the individual water particles. These particles describe circular orbits in deep water with each particle returning to its original position after passage of the wave. The diameters of the circles decrease with depth from a diameter at the surface equal to the wave height. In shallow water the orbital movements become flattened, and at the bottom, if the water depth is shallow, sediments begin to shift (illus.6). SEDIMENT & WATER MOVEMENT 6. The height, length, and period of waves are determined by the distance the generating wind blows over the water, and the length that it blows. The fetch,is therefore, the determining factor for wave develop- ment. Generally, the longer the fetch, the stronger the wind, and the longer the time that the wind blows over the water, the larger the waves will be. If winds of a local storm blow toward the coast, the genera- ted waves will reach the local shore in essentially the form in which they are generated. If the waves are generated by a distant storm, they may travel through many miles of calm water and decay as a result. Waves that have under-gone this type of change will reach the shore as relatively long, low waves (5). CURRENTS & SURGES Currents are created in the oceans, adjacent bays, and tidal marshes when the water in one area becomes higher than the other. Water in the higher zone flows toward the other and a current begins. Causes of differential movement are tides, wind, waves, and stream and river flow Into the ocean. Changes in water temperature also cause changes in water density and produce currents Stich as tile Gulf Stream. As the wind blows over tile water it creates stress, and the water particles move In the saute direction as the wind. Thus, a Surf tee current Is created. When the. water hits a barrier, such as land, a storm" surge"Is experienced. Its velocity depends on wind Speed, direction, fetch, and water depth. "Storm surges" oil tile north Atlantic coast rise to a lesser degree than than that oil tile shallower southern Gulf coast. Waves create a current known as tile "longshore current" when they approach the beach at an angle. These currents are responsible for the transport of sediments along the littoral zone (6). LITTORAL TRANSPORT Littoral transport is defined as the movement of sediments in the nearshore zone by'waves and currents and is divided Into two general classes: transport parallel to the shore, longshore transport. and trans- port perpendicular to the shore, onshore-offshore transport. This transport is distinguished from the mat- erial moved, which is called "litioral drift" (illus.7). Onshore -offshore transpoit Is determined primarily by wave steepneds, sediment size, and beach slope. In general, high steep waves move material offshore, and low waves of long period, move material oushore. Longshore transport results from tile stirring up of sediment by the breaking wave, and the movement of this sediment by tile component of tile wave in an alongshore direction, and by the longshore current gener- ated by tile breaking wave. Tile direction of longshore transport is directly related to tile direction of wave approach, and the angle of tile wave to the shore. The average annual net rate of littoral transport at a given place Is fairly regular from year to year unless the shoreline has been altered by some sort of structure that eliminates or reduces the supply of sand. Obviously, tile rate depends on local shore condi- tions and alignment as well as the energy and direction of wave action in tile area NATURAL STABILIZERS Despite the potential for shoreline erosion along the R. 1. coastline, tile growth of biological coui- munltles on shore and In the intertidal zones help to stabilize tile shifting coastline. The successful es- tablishment of living coutuitinities of plants and animals is very important to these areas. Beach grasses and Shrub communities protect against wind and water induced erosion along barrier beaches and beachs. Salt marsh comutunItles cushion some of the intertidal areas against tile full forces of storm-drivel] water. In all Instances, the presence of healthy vegetation is a natural mechanism providing a more stable base for tile plants themselves, fostering a physically stronger biologic community, and allowing for the expansion 15 Zi qrN "_r. 7. of t'lie community along its margins. The dynamic m1x of natural forcbs along the coast slows the development of large, highly productive and relatively permanent coasEal ecosystems. Some R.I. salt marshes, for " ; I .' instance, have taken thousands of years to grow to their present size. All the while, they are subject to the physical stresses of changing weather, water movement, and dramatic changes in sea level. Yet they sur- vive and grow.,In addition to their value as habitat and sources of primary productivity, natural land- forms, barrier beaches, dunes, beaches, and salt marshes, In the coastal zone provide significant protec- tion from coastal storms, flooding, and erosion. Beaches and. marshes also,. didsipate destructive storm k waves over their gradual slopes*. Dune systems, If stabilized by beach grasses and other binding vegetation, prevent direct wave attack against inland areas. Barrier beaches protect both miinland development and the salt marshes afid pr6ductive habitat between them and the mainland. In order to function effectively as natural buffers, however, these- landforms and the natural proces- ses which link them together must remain relatively free from alterations which would disturb their natural state of "dynamic" equilibrium. For example If natural erosion of one beach Is providing sediment material via littoral transport that is eventually deposited on another beach farther downcoast, it will be Important to prevent any action to retard erosion of the upcoast beach from Impeding the flow of sand to the downcoast beach. As another example, barrier beaches migrate slowly inland and downcoast, but this movement allows them to maintain their elevation and protective capability relative to rising sea level and storm forces. Only monumental climatic alteration or geologic change would be sufficient to destroy or damage the natural resiliance of the coastal ecosystems were it not for the presence of man. Pressure for development of sensitive buffer areas for residential, commercial or recreational uses has been significant in the past, resulting in substantial losses of property during major north- east storms and hurricanes, and impairing the ability of these buffers to protect inland development and other unique aspects of the coastal zone. These man-Induced stresses, however, are not simply occasional; they are widespread.and becoming more frequent. FCOSYSYTEM MANAGEMENT The concept that ecosystems recognizes that all life is interconnected and interdependent. It rests oil the understanding that there is an organization among plants and animals in response to their physical en- vironment that promotes optimal efficiency in capturing, storing, and transforming the energy and chemical elements essential for life and growth within the-group of organisms living in a given area. Since this process occurs both worldwide and locally, it is possible to think of something as large as one global eco- system or as small as the group of plants and animals livingon one type of rock in the intertidal zone. The fundamental physical and chemical conditions In the environment make it possible or impossible for particu- lar organisms to survive in a particular place. It is for this reason that the living world exhibits such variety; species occupying any one place are only those that are adapted to functioning together in their local conditions of sunlight, physical forces, and chemicals.(4). Modern coastal management depends on growing knowledge of ecosystems as the basis for decision making. Such knowledge is also essential to all levels of private and public planning for land and resource use, unlike earlier management techniques that focused efforts on WhOle ecosystems. Changes in any one,part of the ecosystem, however small or remote,cause alterations in all other parts, and sets the pace for management. The coastal zone of Rhode Island has several types of coastal ecosystems, barrier beaches, sand dunes, beaches, salt marshes, barrier wetlands,and cliffs, ledges, and bluffs. While the major elements of each ecosystem are known, and the principals that govern the physical and biological interactions of each are understood, there is still a need for the physical protection of these vitally important natural resources. Ultimately, it will be the degree to which improved knowledge of the coastal systems can be disseminated to, and consistently applied by, all coastal zone users and decision makers that will preserve Rhode Island's coastal resources in the future. 17 VEGETATION.. EROSION A11KFEMENT There are two methods by which erosion can be controlled, either permanent or temporary. Temporary erosion controls are those that are implemented until permanent control has become established. Nature has provided itself with the most efficient means of erosion control., that being vegetation. Where there is a fairly good cover of surface vegetation, along R.I.'s shoreline and adjacent slopes, the ground is stable. Where there Is little or no surface vegetation, these areas are unstable and prone to erosion. The foliage and branches intercept rain that would otherwise fall directly on a elope, their roots bound and stabilize soil, and their fallen leaves and dead twigs reduce the rate of overland water flow. Since indigenous plant species are the most adapted to these areas their chance of survival Is far greater titan those introduced from foreign places. It is a fact that indigenous plant species require lit- tle to no maintenance after they have become established. Planting vegetation on highly erodeable steep slopes 19 hard to acheive, therefore it to here where vegetation should be left in its natural state. Eventhough planLlng on steep slopes is difficult, with the proper knowledge and procedures It is highly possible to achetve with good results. With the availabil- Ity of water becoming a problem more and more people are using Indigenous plants that are more adapted to coastal soils and the climatic conditions that prevail.. A setting of native shrubs and trees grown naturally and Informally can look very neat and appealing without demanding care. In fact, limiting maintenance Is Important to the plants survival. Leaf cover, for example, should be left on the ground under the plants to decompose and build tip organic content withlit the soil. This aids water retention, recycles nutrients, and reduces the risk of erosion. Indigenous plant species require virtually no pesticides. Chemical Insecticides can be counter-productive and deprive the landscape of its natural. vitality. Bugs are important to nature and all are not at odds with landscape objectives. If no hard chemical pesticides are used, temporary Inconveniences In the landscape ittay result: but that is the way nature operates and It i;s best accepted. Landscaping with plants that would grow naturally without care or energy subsidy will support the design and function of the landscape requiring a minimum of supplemental care. This practice not only helps to fight the forces of erosion, but also conserves energy by limiting the need for pesticides, fertilizers, and water, all of which require fossil fuels for processing and delivery. The balance bUnatural systems and all the creatures of nature who depend on a quality functioning natural environment are also protected. A well designed native landscape can help to stop erosion, require limited maintenance, and look the way it Is naturally supposed to, once established. 18 SELECTION The usual method for introducing shrubs and trees is by planting. Seeding is undesireable because of establishment time, cost and difficulty of germination. Planting has the advantege of allowing the plant to be placed in the exact position required to give both physical and visual protection immediately. The rapid drying, especially of steep slopes, makes these sites even more unfacourable for direct seeding. Therefore, the selection of appropriate plant material is necessary. Plant material can be obtained as seed, bare-root, balled and burlapped, or container grown. Direct seeding, is most often done with grasses in spring and late summer or early in the fall. Seeding is difficult on slopes because of the lack of water. When Seeding is done during periods of rain the chance of erosion is greatly increased. For a comprehensive procedure and listing of grass types refer to the state of Rhode Island's, Soil Conservation Service, "Sediment Control Handbook". Bare-root plants, are those that have no soil under their roots. Great care must be taken to be sure that the roots do not dry during planting. Bare root plants should be dug and replanted only when they are dormant. Bailed and burlapped plants, are those that are dug in a nursery with a ball of soil around their roots that is held in place with a burlap wrapping. Container grown plants, are those that are produced in the nursery in a container and sold in that form. The selection of plant species should be governed by the selection of materials appropriate to the site. All plant material chosen should be of normal health and vigor, there survival depends on it. Listed are standards set forth by the, American Nurserymen's Association: 1. The general condition of plant material should be: a. Uniformity of leaf coloration. b. Dormant plants should exhibit firm, moist, and uniformly placed buds. c. Plants should have uniform twig and leaf growth on top and sides, including their base. d. Generally, plants of the same species should exhibit the same growth habit. e. Balled and burlapped plants should have a firm root ball of relatively good size. 2. Check individual plants for for freedom of defects. a. Decay. Look for spots of rotten tissue on the main stem and branches. b. Sunscald. Look for areas on bark that is differing in color,usually on the south or west side. c. Abrasions of the bark. d. Girdling roots that are close to the surface and circling the trunk or main stem. e. Improper pruning. Stubs left are point of entry for insects and diseae. If cuts are made, they should be flush with trunk, or if on branch it should be back to the bud. f. Frost cracks. Long vertical splits in the bark on south and southwest side. Entry for fungi and bacteria. g. Signs of injury. Dead leaves,and flower buds,die back of twigs and branches;blackened sapwood; sunken patches of discolored bark,sunscald,on trunk or limbs. 3. Check individual plants for freedom of diseases and insects. a. Diseases. Will appear in many forms such as abnormal growth of leavs,twigs,fruits, discoloration of leaves and bark,unusual discharge of sap through the bark,etc. Any plants showing these signs reject. b. Insects. Look for eggs, evidence of leaf feeding,and twig,bark and trunk feeding. Look for bore holes in trunk and bark. Trees showing any of these signs reject. 3. Check all container grown plants for healthy root systems. Plants that are found to be pot bound, wrapped around the interior of the container,and plants that have insufficiently developed root systems, will not hold the soil together when removed from the container and should be rejected. Healthy roots should be able to hold the soil mass together yet not be crowded around the outside. They will appear whitish in color. DE LIVERY In spite of the desirability of ordering trees and shrubs from a nursery close at hand in order to minimize delivery time and to obtain stock acclimatised as possible to the site, it is often necessary to order from more distant and larger nurseries with a wider range of species and cheaper stock. Speed of delivery has always been recognized as an essential, the more so on difficult sites where the good condition of delivered stock may be a very important factor in the success of the operation. Most large nurseries deliver by road whenever possible. All possible steps must be taken to minimize the time during which the plants are out of the ground. As soon as the plants are received, care should be taken to ensure that the roots are kept covered with a material to keep them moist. Balled and burlapped material should be protected from drying damage and should also be kept moist by watering and covering the root ball (7). 20 SITE PREP Grading and earth moulding operations however necessary fbr,erosion control or land use,.may often be detrimental to the growth of trees and shrubs planted shortly afterwards. The heavy machinery or heavy foot traffic can cause compaction of the soil with loss of structure and reduction in soil aeration. This happens particularly in areas of high clay content. Apart from compaction and air loss, grading disturbs the natural contours of landforms, causing soils to lose moisture, and increases the velocity of runoff. Site preparation should be done with regard to: -Natural contours of the land should remain unless proven othl@rwise. -Proper site preparation is Important to insure the successful establishment of newly implemented plants. -Site prep and planting should be backed to minimize moisture loss in soil. -Large sites should be prepared and planted in sections to limit exposure of slope. -Remove and disturb only what is necessary. -Vehicular and foot traffic should be localized to maintain slope stability. -All materials to be disposed of should be removed from the site vicinity. -Hay bales or approved equal should be used on the toe,top,aud back of slope to reduce runoff velocity (illus.8). PLANTING Ideally planting takes place while the plant is dormant, after the plant has hardened off after the last years growth, this being the period during the end of October to the beginning of April. Provided periods of cold winds and frost are avoided, planting can go on throughout the winter and spring with reasonable success. If new plantings go into the winter, t4hen the humidity is low and winds are high, the mortality rate of new plants is most likely to be high. Therefore, it is important to supply new plantings with adequate moisture so that they do not become dehydrated during the winter months. Hot dry summer months are also critical (7). Plants growing naturally spread by underground runners, rhizomes, and by seeds. When they spread and grow naturally they often form dense clusters. The feasibility to produce this type of appearance is not economical and can not always be done. If plants are spaced closely they have the ability to obtain surface stabilization by the root network sooner. This is not to say that plants cannot be placed in such a way they take on a natural character. Too often plants are placed in the landscape in neat straight lines, and In order to maintain their appearance they must be maintained. Maintenance is often difficult on slopes. The placing of plants so they take on natural character will contribute to the visual quality,of the coastal zone landscape (illus.9). r"". vvy mw.& rwxr- or WNW f rmwuf .;,r,t7lM forzrniq eouw wo HAY mm,5 .4 AFMF70@ WOK A"fM[Vy P5 evbfAt- w Plants should be spaced according to their growth habit and size. On slopes plants can be spaced closer on slopes if desired because each plant receives a higher percentage of light from all sides,espe- cially on southern facing slopes. Reccomendations for planting are: -Slope should be saturated with water to a depth of 4-6inches prior to pJantIng. -All planting should be done from top of elope to base whenever possible. -Ground cover should be used on slope for water retention and slope protection. -11ay bales or approved equal should be used at toe,top,and back of slope for runoff protection an(] sedimentation (illus.8). SOI L PR E P The soil's ability to retain moisture and provide chemical nutrients is essential for the establishment of newly planted plants.The soil pil indicates, to a certain extent,ithe nature of Lhe Internal chemical processes of solls which determine the state dr condition of soil fertility. Every kind of plant is be- lieved to have a most suitable soil reaction or pil range for Its best growth. The average range for soll pil Is from 4.5 - 9.0. The minimum pH limit designates the strongest acidity, and tile maxi-Iflum pil Ilitilt indicates the strongest alkalinity the plant will tolerate without the possibility of serious Injury (8). i Since moisture to of main concern for enabling plants to become established the preparation of exist- Ing sol.1 Is r&Eommended. Loam is a good moisture retainer, -peat is a moisture retainer and provides acid, and manure is a good source for organic material. It is recommended that the soils for planting pits be prepared since they are generally well drained along Rhode Island's coastline. For optimum success of new plants soil preparation is essential. Further Information can be acquired from a professional or from tile R.I. Soil Conservation Service (9). G. COVER Low growing ground cover in close proximity will prevent surface erosion more effectively than trees and shrubs which are necessarily spaced further apart. Ground cover plantings have been used extensively throtighout the U.S. along highway cuts for soil stabilization and have proven effective. They can be used along with tree and shrub planting for extra soil protection, design feature, or for steep slopes where tree and shrub planting is difficult. 24 Procedure for planting GROUND COVER I-Cover watered area of slope for planting with an even layer of mul.ch approx. 2 - 3 Inches. 2-Plant at previous planting depth and space according to effect desired keeping in mind the closer the better protection. 3-Water after planting Is complete to help bind mulch. 4-When handling ground cover remember never to let root system to dry out. Keep moist. Maintenance -Water for first growing season. -Check mulch to make sure it remains in tact%and control competing weeds. MULCH Mulches protect expoded soils, retain moisture:,necessary for plant establishment, and some decompose with time and provide organic material to the soil. Mulches can be either temporary, like jute netting,oi- or permanent, like shredded bark. Recommended mulches are as follow: Hay o Straw Jute Netting-Burla 75-100lbs. per acre. Used in critical areas of concentrated Good for steep slopes and other critical areas. water flow. Keep molst,they are subject to wind blowing. Best for steep slope. Salt marsh hay can be used where applicable. Must be anchored with pins etc.,refer to manufacturer or professionals recommend-.0, Manure ation. I inch cover. Brush Introduces weeds. Adds fertility. Cut brush can.be scaftered on slope. Subject to odor. Introduces weeds and other plants. Not recommended for under n6w plants. Peg and Twine Shredded Bark Used to anchor hay or straw from wind. Stretch twine between driven pegs in criss-cross Apply molst. manner. 3"minimum depth. Pegs 8-10" long,3'-4' on center. Water after installation for stability. SHRUBS Shrub planting is mosu effective on low -moderate slopes. Existing shrubs should be saved whenever possible. Procedure for planting SHRUBS I-Choose plant species beat suited to site. 2-Dig planting pit 6"wider and 12"deeper than roots. 3-Fill bottom 12" of pit with prepared soil and place in plant. 4-Add prepared soil to fill;pit 112 full,add water and allow to settle. 5-Never allow soil level to go above-previous mark on main stem. 6-If present, fold burlap from top of ball and fill pit with soil. 7-Form-saucer around plant and thoroughly water; 8-Place mulch on top of planted surface foromaximum moisture retention. TREES Tree planting Is most effective and easily acheived on low and moderate slopes.Extating trees should be saved whenever possible. Procedure for planting TREES I-Same as shrub. 2-Stake trees with 37stakes approx. 120 degreea apart. 3-Stakes can be away from root ball or firm against It for added support. 4-Ties to be placed directly above first limb,use protective material between wire and bark. 5-For maximum support drive stakes a standard of 2-3'. MAINTENANCE -Trees and Shrubs require water for first growing season. -Control competing weeds until plants become established. -Check mulch for stability. Sotirces: (9,10,11,12) 26 .01 An 1-41 P. A WHWr, KP fop :6L)P -:5011- [OW MTWAII@ dog 0 0@ wwlo, JVU-4 H,.,MW 410A COASTAL WETLANDS I COASTAL WETLANDS In Rhode Island, coastal wetlands are inundated with saline water semi dlurnally. Technically these coastal systems are classified as salt marshes, based on the plant species that exist and the tidal influence. These salt marshes are flexible features that can change in shape as sea level rises and as sediments erode and are carried into these areas via water. R.I. has a total of 3,668 acres of salt marsh and 76 acres of fringe marsh that are generally less than ten yards wide (13). According to Rhode Island State Law, a coastal wetland shall mean any salt marsh bordering on the tidal waters of this state, whether or not the tidal waters reach the littoral areas through natural or artificial water courses, and such uplands directly associated and contiguous thereto which are necessary to preserve the integrity of such marsh. Marshes shall include those areas upon which grow one or more of the following: smooth cordgrass (Spartina alterniflora), salt meadow grass (Spartina patens), spike grass (Distichlis spicata), black rush (Juncus gerardi), saltwort (Salicornia spp.), sea lavender (Limonium carolinianum), salt marsh bullrush (Scirpus spp.), high-tide bush (IVa frutescens), tall reed (Phragmites communis), tall cordgrass (Spartina pectinata), broadleaf cattail (Typha latifolia), narrowleaf cattail (Typha angustifolia), spike rush (Eleocharia rostellata), chairmaker's rush (Scirpus amercana), creeping bentgrass (Agrostis palustris), sweet grass (Hierochloe odorata), wild rye (Elymus virginicus). SALT MARSH FRINGE MARSH Salt marshes are found along the Narragansett Bay and Sokonnet River shorelines and outside their proper limits. They occur in sheltered waters that are protected from ocean waves and strong currents. Those that exist outside the properlimits are generally found along the southern shore of R.I.. These are sheltered from the ocean by barrier beaches, turned barrier spits. The term given to these marshes is "Barrier Wetlands". Salt marshes in R.I. range from highly altered ponds like Point Judith, to small undeveloped ponds like Trustom which is in a rural setting. Wherever they exist they are all beginning to feel the pressures of development. The salt marsh is one of the most important ecosystems along the R.I. coastline with its' net primary productivity far surpassing that of any other environmental ecosystem. The salt marsh can be viewed as a self sustaining life support unit, transferring food and chemicals back and forth between the productive land system and the open ocean. As such, it fills a vital role in maintaining the physical-biological character of the near shore coastal area as well as supporting life in both terrestrial and aquatic zones (14). NATURAL INVENTORY PHYSIOGRAPHY .. GEOLOGY The Original physical form of Rhode Island's salt marshes was created by geologic and glacial processes primarily during the last ice age roughly 12,000 yrs. ago. Each salt marsh has its own identity, primarily based on physiographic form. As the glacier melted heavy till was layed down and the meltwaters carrier finer outwash to lower lying areas. As sea level rose the low lying land was covered by salt water and was first colonized by algae, and where the water was shallow aquatic grasses became established. The grasses trapped fine sediments and as the elevation increased terrestrial vegetation took over. The vegetation then trapped more sediments that were suspended in fresh water stream and river outlets and in tidal waters (illus.13). Two conspicuous physiographic features of the salt marsh are meandering creeks, that carry fresh and tidal waters during high and low tides. If shallow enough, the water may evaporate leaving a concentration of salt. Meandering creeks are formed by a complex process dependent on surface irregularities and the deflection of water. These aforementioned salt marsh characteristics are delineated by a rise in topography inland ranging from several feet to 35ft. (illus.14). Barrier wetland formation has been a result of glaciation also but in a different way. The southern shoreline is the result of later modification of glacial action caused by marine erosion and deposition. Along this area the Charlestown Moraine exists. Here the glacier maintained a stationary front long enough to allow outwash to flow out into the meltwater. This outwash formed a low relatively flat plain (illus.15). After sea level rose however, a large portion of the outwash plain was covered. As currents began to form barrier spits the salt marshes started to establish themselves in much the same way as other initially more protected coastal wetlands began (2). ZE -14 7K Aa 4.1 YUk AT W 44 MT Ilk Is NN tpk Wr" 10 HIt., WF-Ir-r- W11 lic., VIC, jp !I sit. ,iu WfWWA 15. SOILS Within Rhode Island's salt marshes peat and muck Is found atop glacial. outwash,, till.1 'or both. Peat is formed by decaying matter which is in excess. This peat is highly acid due to a complete lack of oxygen caused by both chemical processes and constant waterlogging. Some of the more pristine salt marshes have a peat layer several feet thick. The adjacent upland slopes consist of a thin layer of organic material, where vegetation is or was once prevelent, underlayed by outwash or till over bedrock. The till and,or out- wash vary In thickness depending upon location (2,15). HYDROLOGY Salt marshes are the meeting and mixing grounds for fresh land based water and saline tidal waters. The fresh water content of a salt marsh is dependent upon rainfall and and that which is derived from sur- face flow, channeled flow, or subsurface flow.from the land. Surface flow is intermittent and normally follows rainfall or melting snow. Channeled flow includes all permanent and temporary rivers, streams and creeks, along with all intermittently flooded drainageways, swales, and so forth-which convey land run6ff toward coastal wetlands. Subsurface flow is derived from soil that hag a large capacity for water storage when its surface Is open. This water however, moves through the soil at a rate much slower than the others, although this time allows for removal of pollutant6 by natural filtration. Salt water influence varies according to wind, tide, and current amounts and velocities. The influx of salt water is essential to the survival of a salt marsh. The flushing action of tides seems to take away and bring in sediments and nutrients necessary for.life support both in the marsh and adjacent waters. The nat@ ural drainage pattern must be presumed to be beneficial, both In the manner by which waterborne nutrionts and sediments are delivered to the marsh and the rate of delivery (4,16). Sedimentation from cleared upland areas would prove to be detrimental to the life of salt marshes. VEGETATION As in all biological systems, vegetation serves a variety of roles in the marsh. It is able to use solar radiation and nutrients to produce food; it reduces extreme temperatures, it transfers moisture frow the soil to the air by means of transpiration, and it adds organic material to the marsh soil. While marsh plants use a large amount of food they produce In order to survive in their rigorous environment, the re- mainder is available to be used as a source or nutrients by other plants and animals. This contribution can be substantial considering that each year, anywhere from five to ten tons of organic matter may be produced by each acre of salt marsh. Wheat fields, by comparison, yield one and one-half tons per acre per year, hay fields, four tons per acre per year, and deserts and oceans, one-third of a ton per year, making the salt marsh one of the most productive of all ecosystems (17). SImilar to most Intertidal biotic communities, Rhode Island's salt marshes generally show clear patterns of zonation (illus.16). In general the variety and complexity of plant communities are greater In the larger marshes. In some marshes the zonation pattern is broken Into a mosaic pattern; In other- usoally smaller marshes, one or more of the zones may be present. Fringe marsh is frequently composed almost ex- clusively of Spartina alternifolia (cordgrass). Along the bordering slopes plant communities differ from site to site also. Besides marsh and bordering plants contributing to the productivity of the marsh, microscopic algae covering the muddy surfaces also contribute. They are essential food sources for small Invertebrate an].- mals. After the plant and algae have produced a seasons growth, they die back and become detritus. Decompo- sers, which are primarily aquatic bacteria, fungi, and protozoans, break down the detritus Into minerals, gasses, and water. These by-products of detritus form the basis for aquatic life in and outside the HiAts of the salt marshes aquatic realm, as seen in the following Illustration (15,17). MOPM 6Y4r____ 36 ION :L4 MAI? W 1--- 4A 16. BIOTIC COMMUNITY The salt regime of the marsh community has been a ma. Jor factor in restricting the number of animal. and warine species that Inhabitat the marsh. Among marine animals only a relatively few can adjust to the rapid salinity changes that occur with the tides. Those few that do adjust can endure tidal marsh condi" Lions. These few aquatic species are relatively free of the kinds of competitors and enimies that harass related species in nearby waters.Usually only a few species are prominent but upward of 60 species of fishes have been found In tidal streams (17). The marsh vegetation supports not only a resident population of marine life but "migrants" as well, Including mammals such as the raccoon and the oposatim, and several species of Bong birds. The raccoon, visits the water's edge at low tide where it digs and eats mussels and crabs. The meadow mouse moves into the lower slope from the fringing upland. There It feeds upon Lite vegetation; It Is preyed upon by owls and hawks. The muskrat Is a permanent resident In the less saline parts of the marsh where it feeds on an abun- dance of bulrushes and cat-tails. While most species of eastern U.S. birds may be found In the ittarshes, only a few species are charac- teristic of the salt marsh and either breed there or closely frequent it. The more common species include certain rails and sparrows, the black duck, blue-wioged teal, certain shorebirds, the marsh hawk, short - eared owl, red-wing blackbird, meadowlark, and marsh wren. Herons also frequent salt marshes. Salt marshes also play a role to certain migratory birds like the canadian goose. Many of the birds support their diets by eating small fishes, aquatic Insects, snails, add plants (15,18). It to the adjacent upland environments where these -associated marsh species seek shelter when not feeding on Lite marsh.Here is where efforts must be made to provide suitable habitats for these Important marsh creatures. 38 AESTHETIC ENVIRONMENT The aesthetic quality of Rhode Island'ql salt marshes is based on the unity of landform, water, and vegetation. The.aesthetic environment offers uniq!M variety and vividness. Variety is seen and vividness is perceived as a strong, clear impression on 01-esenses. Variety and vividness is derived from terrain pat- terns, presence of water, weather characteristics, vegetation patterns, and cultural land use patterns. Uniqueness is derived from the composition of form, space, color, and texrure. Views in and around salt marshes are contained by the bordering landforms. Generally, the densely vegetated hill and valley topography has become disturbed by cultural development. Development along the marsh perimeters has, in most cases, drastically altered their natural unity. In places where vegetation has become re-established the built And altered landscape has become subordinate and unified once again. It is on the edges, where marsh meets land, that strong focal points exist. Alteration*of unity at this point goes unnoticed and becomes visually degrading if not handled properly. The following illustra- tion was done of an edge condition in Rhode Island. Three different coastal edges exist. Two are vis- ually degrading. These dominate hard lined edges their textures,and their colors are visually de- grading,not to mention their physical degradation. M V to -On They totally alter the marsh unity. The natural -nq edge his variety in its' own right. It gives the viewer the perception and feeling of salt marsh. It also reduces the dominance of the ad acent --7: house-and it supports life in the marsh,and acts as a natural buffer to waves and currents. The W choice to save the vegetation also saved the natural character of the slope and landform. LOA On the following page the next illustration was drawniseveral hundred yards downshore from the above illustration. Here the altered coastal edge is less dominate. Instead of altering the total edge terracing was used;it enabled the landform to maintain its natural form. Wood as a material lit this case helps to maintain the composition and be- comes subordinate. There is a certain quality to this setting that gives the marsh a pleas- ing vitality. If alteration to the coastal edge is to be done it should add to the visual and .- sensory resource. 40 EXISTING.. PROPOSED SOLUTIONS Erosion occurs on the surface of slopes bordering Rhode Island salt marshes. Surface instability leading to erosion can occur on otherwise stable slopes because of the breakdown or stripping of vegeta- tion. This breakdown and stripping of vegetation generally occurs during construction of property adjac- ent to salt marshes (illus.17). The exposed soil is able to erode and cause sedimentation to occur on the slope and marsh. Further activity can cause channeling of water..This is when water collects In a footprint, tire track, and etc..This channeling accelerates the flow of water that gradually cuts down through the soil and forms rills.which can form into gullies. Channeling, rills, and gullies should be avoided hence, they are capable of transporting large quantities of sediment. The aforementioned activity can be avoided by minimizing activity on and near the slope (illus.18) by instituting a setback line to: -Insure conservation of landform and*vegetat-ion. -Maintain visual,biological,and ecological quality. -Reduce risk of erosion and sedimentation. -Prevent bulldozing of soil and vegetation over slope. If the land and slope is classified as severe then (fllus.8,p'age22) should be followed to: -Reduce velocity of runoff. -Reduce sediment transport onto slope and into marsh. -Maintain visual quality of landscape after construction. Another common unaccepted activity along the coastline of salt marshes Is to construct revetments. Revetments are in the form of seawalls and stone rip-iap.(Illus.19). The procedure here, prior to the Coastal Zone Act, was to build a seawall and to dump fill to extend property or the fill was dumped and the rip-rapwas used to hold it in place and prevent toe erosion. Rio-Rap is still being used to date and It causes impact to the salt marsh: -Alters natural runoff patterns -Reduces subsurface water flow -11olds back chemical nutrients -Restricts vegetation from encroaching intamarsh. -Alters aesthetic environment. The practice of constructing seawalls was not unnoticed by the CRMC, and is no longer allowed unless absolutely necessary. 11owever, existing seawalls are being undermined and repair Is often requested. This should no longer be accepted as the norm since it has been proven they cause severe impacts. They should be removed and what is necessary should be done to allow salt marsh vegetation to,flourish once again. The seawall can be removed and the land sloped to its natural angle of repose. If Insufficient space is provided then the filling of marsh for vegetation establishment may be considered worthwhile. This would eliminate the typical procedure of filling toe of seawall with stone (Illus.20). Access to the waters edge through salt inarshes is often required,although methods to protect the salt marsh vegetation become visually degrading when it Is not necessary. The best accepted method would be to lower the boardwalk to the point where it doesn't become dominate within the landscape and so it does not .rest on the marsh vegetation (illus.21). Keep In mind: -Low level boardwalks should be used when necessary. -They become subordinate and do not visually and pf'iyalcally degrade salt Inarshes to a large degree. -Wood is beat material-it holds up to weather,and tends to blend with the environment. -Boardwalks save marshes by localizing access. -Allow access to waters edge during high and low tides. -Save vegetation from foot traffic. At certain locations where slope erosion has begun to threaten property the first step toward solving the problem Is to define the erosional forces effecting the slope. After the problem has been defined, then choose from the range of proposed controls outlined in the barrier beach-aud beach sections. It Is possible to use one or a combination of solutions to solve the specific problem. For a listing of plant species best adapted for coastal use refer to pages(104-108). 42 10 @xp-@w -A;kgl @0[- HAb I OeOW 4ir .Aoor IZZOMMIM r@VVA F IU 'Aw I j Vol 17. @l H roe I"p ffwm 4WS off MM Nl*HrA12 ALAA AA A jA mll-w ol fir 19. ot. fo At FXK Wf VO',@Mf W V*j q 20. POMIHAfr,- 21. SALT MARSH ESTABLIS14mr4,NT Salt marsh development, improvement, and management was initially done to provide water fowl habitats at the tur'n of the century. During the last decade the technology of tidal marsh establishment has evolved considerably. There have been extensive projects ranging from Virginia to the northern Chesapeake, and throughout other parts of the U.S.. The gentleman responsible for the majority of norlitern east coast work Is, Edward Garbisch Jr. from, Maryland. SHORE EROSION ABATEMENT Marsh establishment along eroding shoreline batiks may provide effective erosion conLrol.'The estab- Halted marsh functions as a biological buffer, absorbing wave and current energy as they pass through. Sed- Iment from alongshore drift and from bank and slope erosion is trapped within the stand of marsh grass and the shore Increases in elevation. As the,sbore elevation Increases, the contact time of tidal water with the eroding bank decreases. The contact time may only occur with periods of storm tides. Generally, the wider the band of marsh that can be developed seaward of the eroding bank, the more effective will. be the erosion abatement. A six to ten foot wide band is the.narrowest that can be expected to provide meaningful erosion abatement.(19). 5.e "t 4. Milk W May planting 2 months later 48 GUIDELINES FOR SITE SUITABILITIES Tidal amplitudes, currents, wave dynamics, water salinities, and directionsand volumes of sediment transport are variable throughout the coastal zone. It is improbable that any two locations will have the same variables replicated. Consequently, the designs and specifications for marsh establishment must be site specific. The application of guidelines should be tempered with judgement based on local conditions. If natural marshes exist in the area of the site, preferably the immediate area, new marshes can be established artificially either on fill materials or on existing sediments-@of suitable elevations. New marshes sometimes can be developed In areas where prevailing stresses are too severe to allow natural marsh establishment. Generally, in areas subject to open water fetches in excess of nine miles are not likely to be suited for cistablishment. Sediment, or substrate surface elevation is a most critical parameter for site suitability. It is recommended by Garbisch, to set the low elevation vegetative boundary at the Mean Tide elevation. As pre- viously stated, if shoreline erosion abatement is of.concern, a minimum vegetative band width of 6'10 ft. is required. The erosion abatement will increade with increasing vegetation band widtfi; however, if sandy sediment can be trapped, a 15-20 ft. band of marsh vegetation will control a broad range of shore erosion situations. To estimate the width of shore that is available for marsh establishment, measure-fhe width of non- flooded shore three hours after or before the predicted high tide for the area (illus.22). This measurement sbould be made at a time when no major weather systems are passing or have recently passed through the area. Also, it is advisable to make the band width measurement on a day when tide tables predict average low tides (19,20). Shading markedly restricts the productivity of most marsh vegetation. All areas of the site should be exposed to direct sunlight for at least four hours each.day during the growing seAson. Shoreline trees should be removed or pruned to permit the necessary exposure to direct sunlight. Heavily wooded and steep sloped shorelines facing north may never receive the required sunlight to allow marsh establishment. Other vegetative erosion controls should be used. P 3A @f H 6HMrmf rvw ImfiH& WH-r[ZVPr-P AFFA fO rr- M rAb U " 3 h rb. M-1 W lVi1*116 rf- io rf KUMI,- HEM OK IoWd I pr. 3hr Mlf ------ ww M61M [pr IM"-CJY-,P M. 014 Ir- 0 All MUHL" 3[r. 1411f ------ H.W. MAK5 PAV 22, SITE PREP Substrate types. There is no apparent limitation of uncontaminated substrate types to marsh estab- lishment. Clay, silt, sand, and peat and combinations thereof are acceptable for marsh establishment. Be- cause of its poor fertility, poor nutrient absorption capacity, and unsuitability for grading and for most seeding and transplantipg cechniques, marsh peat is the least desireable substrate for marsh establishment. _@lUes. Surface slopes should be as low as practicable without Impounding water and should not exceed Lhose that are unstable tinder normal conditions in the absence of vegetative cover. Elevations. Surface elevations are the key to successful marsh establishment. In areas subject to low tidal amplitudes of two feet or less, acceptable elevation tolerances are most stringent. Variances of just inches could mean unsuitability for establishment. The existing or proposed elevations of a particular site should be tied in with those in the immediate area that support the marsh types designed for establishment (22). PIANTING �2rlg and Bare Root Plants. Sprigs are single culm plants. A culm may contain several single stemed plants. If gathered in the field they should be collected in late winter or early spring before the plants resume vigorous spring growth. Early growth Is derived from stored energy and It is important to plant before the spring growing season so plants can root and become established before the warm summer months. Otherwise a high mortality rate should be expected. Mortalities can also be reduced by cutting back the aerial part of the transplant to reduce transpiration. Bare root plants are normally single plants that have been gathered or ordered. If ordered they have most likely been grown from seed. If bare root plants are purchased they could be held outside In tubs.of estuarine water for approximately 2-3 weeks. Planting should be done no later than June In Rhode Island. Sprigs and bare root plants of Spartina patens should be transplanted on a grid of!lft. and Spartina alterniflora on a grid of 1.5-2ft. (illus.23). Uniform cover can be expected during the second growing season. It is recommended that three bare root plants be placed in each planting pit (21,22). ell Will VAt.- F". fo W,H -WUI -.:, aur @ AT- 1520 MR. IN; MAr,) U-1-3 @1*13- .,23 Peat potted stock that has been ordered can also be used. This type has been the most successful In terms of survival, sustaining site stresses, and providing flexibility in establishment. Peat potted stock is the most expensive. It has the advantage being.planted any time of the year and can be held over at the site for as long as six months. The extraction of transplant material from a natural stand of marsh can be a very laborious process, and if not done properly can damage the site.It should be avoided since the existing stand of vegetation can be severely impacted upon. Any ordered plant material should come from a local source. For local listings contact the Division of Fish and Wildlife. After planting has been completed a slow release fertilizer should be applied by side dressing. For late winter or early spring apply one ounce,of 8-9month release Osmocote 18-6-12 fertilizer per transplant. For mid-spring to early summer, apply one ounce 3-4 month release Osmocote 19-6-12 fertilizer per plant. According to Garbisch, water salinities do not have an effect on nutrient release properties of fertilizer (19,22). FAC1YJRS LIMITING ESTABLIMIENT Assuming that toxic substances are not present in the substrate or ill tidal waters, wave and salt stresses are the most important factors limiting vegetative establishment. Salt concentrations are most likely to arise in areas where tidal waters have a salinity content of, 20-30ppt,itaving porous sandy'substrates as opposed to muddy or peaty substrates, and within the M.H.W. and spring tide elevation range. In such areas and during times of summer drought and wind setup leading to extended periods of unusually low tides, evaporation of soil moisture leads to increases in soil and soil solution salinities. Capillary action tends to carry salt water to the sediment surface where it evaporates, leaving deposits of crystalline salt and creating a soil salinity that decreases sharply with depth (20,22). Unfortunately, salt stress problems are difficult to forcast. They telate to meteorological conditions and regional. wind and tide influences. Toxic salt concentrations may develop months after an area is plant-t ed. Vegetative establishment should not be attempted during periods of concentrated sAlifitty levels. Planting should be delayed until rain or tidal water reduce the salinity level. if there is a liklihood of salt stress developing at a site, it would be advisable to consider trans- planting the planted vegetation into trenches (illus.23). This will put the plants In a lower salinity zone, and the salt would tend to be drawn to a higher salinity zone (22). MAINTENANCE Three principal maintenance requirements for wetland establishment or restoration are: debris and litter removal, protection against waterfowl depredation, and fertilization. Organic litter which often deposits throughout the uppermost elevations of the tide should be period- ically removed, especially during the first growing season. Stich litter can produce extensive damage even to natural stands of wetlands. During the latter part of the growing season, submerged aquatic plants begin washing out and depositing throughout the upper elevations of the tidal zone. Such,deposits can have a par- ticularly adverse impact to newly planted salt marsh vegetation, and should be removed-(22). Populations of Canada geese can also be detrimental to salt marsh grass. Geese normally feed on 111arsh grass from the seaward edge in. Their feeding habits can be detrimental for the first two growing seasons of newly planted marsh grass. The stringing of nylon line onto stakes has proven effective in other south- ern locations. Normally 1/8" nylon line is tightly strung to 15-20"spaced wooden posts that extend from, 6" above the sediment surface to roughly 6" above Mean High Water (19). Fertilization required beyond those previously mentioned depend on water quality and wave stress at the site. When plant development is inferior to that found in other marshes then fertilization should be conducted. Where high physical stress occurs on site then fertilization should take place every other year. Fertilizer should be surface broadcasted at ebb tide. For further information contact the state Division of Fish and Wildlife. 54 BARRIER BEACHES BARRIER BEACHES In Rhode Island barrier beaches are located along the southwest shoreline; extend-Ing from Jerusalem Beach west to Napatree Point, in Westerly, and along the eastern shoreline from Sakonnet Pt. to Ouicksand Pond, In Little Compton, and along the northeastern shoreline of Block Island. Barrier beaches have been defined by the Rhode Island Coastal Resources Management Program as; WNW-- narrow strips of land made of Z unconsolidated material extend- Ing roughly parallel to the general coastal trend and separated from the mainland by a relatively narrow body of fresh, brackish or a wetland'."' 72M Along barrier beaches exist sand dunes. They are an important and integral part of the beach and COM- monly form a ridge running parallel with the trend of the beach. D4neu and barrier beaches are rugged, they receive the full bruht of ocean storms. They do not have delicate and easily damaged tidal areas Aike the salt marshes ot confined waters. Dunes and barrier beaches are tough and resilient. They require minimum management attention if not vulnerable to destruction by construction and users. unlike, beaches dunes can be easily damaged and require extensive safeguards if Improperly used and abused. Their great capacity to 55 store sand makes them the chief stabilizer of the ocean beachfront. When the dunes are damaged so that they erode away, the essential buffer is gone and the whole shore and adjacent low-lying inland area is threat-.-! eued with each storm or hurricane. A generally poor understanding of the development of both barrier beach- es and sand dunes to withstand alteration has frequently led to disastrous and expensive consequences. Rhode Island barrier beach systems are very delicate, and in an undisturbed state are a public@asset of the greatest degree. Approximately 65% of R.I.'s 27.3 miles of barrier beaches are undeveloped. The recreational opportunities and uniquely beautiful open space they provide are of Immediate and growing ben- efit in an Increasingly developed region. It is a fact that these areas are being more heavily used each year by growing local populations and by increased tourist populations. Therefore, it is of utmost impor- tance for people to understand how they can be better become a part of these exceptionally dynamic features. NATURAL INVENTORY, PHYSIOGRAPHY .. CEOLOGY The natural physical form of Rhode Island barrier beaches is a result of both geblogic and natural forces. They have formed as a result of energy transferred by wind, waves, and currents.' They have been delineated according to topographic form as seen below. Barrier beaches typically formed as sand spits with their sediments being derived from accumulations at headlands. The transport of sediments, to form barrier beaches was done by longshore currents, running primarily In a direction from west to east (illus.24).As the spits continued to accumulate sediments they grew in size and became attached to the adjacent headland. Technically, these barrier spits are termed "Bay-mouth Bars".11ence, there remains a body of water on the landward aide. Often during storms and hurri- canes these spits become breached by wave energy and currents and the inland body of water becomes tidal once again. These breachways become 'static when sediments fill them in and close them off from the ocean (23). Once the bay-mouth bar becomes wide and stable dunes form directly behind the beach because of the invasion of vegetation. When sand accumulates on the seaward slope of a dune it will extend, or build, the dune seaward toward the ocean. According to the Rhode Island Coastal Resources Management Program: "A sand dune is an elevated accumulation of sand formed by wind action and normally follows tile gen- eral coastal trend Immediately inland of an unvegetated beach." Refer to the illustration on the following page. Barrier beaches are ever-changing landforms. They are constantly under pressure by the natural forces to migrate inland. The annual rate is approximately 4 feet (24). To the casual observer this Inland advance is not obvious until photographs are examined or until exposed peat substrates are uncovered on barrier beaches during storm activity. This substrate that Is normally found 30-40 inches under the ocean beach Is proof that inarsh once flourished farther out to sea (illus.26). During periods of increased wave activity, primarily In winter months, the beach topography undergoes change. Waves attack the beach berm fronting the dune and when it is completely diminished they begin to attack the dune and transport the berm and dune sand offshore and deposit it onto a bar. During periods of calm the ocean swells will transport; the sand back onto the beach and the wind will transport it further atop a newly forming dune (Illus.25). This dune building, however, is generally at a very slow rate (24). 57 V VV. ;..., XQ VL Nix Ail t VJNF@ gm 14 i,.@ vl;.I.@,, ? RHODE ISLAND SAND DUNE DELIMITATIONS 6S oe ...... ... Par arm -1 F- WAVr. wr,,ray MA 'aij 4-41 A. V41 1"441 "VT I we 71. P @j I(AH WAVr- MrPY @)rorf 6ff-/ A ij Zf U-4 "R. r; iftt4 25. SOILS Barrier beaches consist of sorted sands and gravel derived from headlands and Inland areas? Generally, these soils are found along the southwestern barrier beaches, whereas the barrier beaches along the .eastern shore have accumulations of pebbles and in certain areas cobbles have been left by eroded till.. Generally, the soils on the southwestern barrier beaches are derived from outwash. Due to the porous nature of these coarse materials water percolates through them very rapidly. Salt derived from ocean water leaches through at the same rate. On the backdune Is where winds have deposited larger accumulations of salt. In soils containing organic matter, near vegetation higher percentages of salt prevail. By nature, the water retainIng clay and organic soils, retain moisture and trap salts.The pil level of these salty soils to generally high causing them to fall into tile alkaline range (25). Sand dunes consist of fine light weight sands. These sands are rounded In shape and hold a very low natural angle of repose unless bonded by moisture or vegetation. Whibn water surrounds sand particles It enables them to become bonded and they are able to support one another. Moist sands hold an Increased degree of slope. Vegetation plays the saute role, although the plant roots act more as anchors. HYDROLOGY Longshore currents transport sediments via water. This Is a constant process and large quantities of sediments can be transported. The direction of current Is dependent upon waves, wind and tides. Not only are currents running parallel to the shoreline responsible for sediment transfer, but waves play allarge role*In causing "Washovers". These occur when waves and water penetrate through the dune line and Inundate low-lying Inland areas. The_Sreat force behind the flow of water has literally l6veled dunes In the past (illus.26). The forces of water seem to dictate activity on barrier beaches over an extended period of time. The force Is responsible for the well-being of barrier beaches as well as the destruction and there is assurance that nothing will defeat its force without causing impact down the line. 61 77 VECErNrION Plants of the high energy barrier beaches are part of a very dynamic natural system and are subjected to some unusual stresses. The stresses experienced by plants varies according to the physiographic form of the barrier beach. Within each zone there exists a plant community (illus.27). Each plant community exists because of Its ability to adapt. Within the barrier beach plants are exposed to tile critical effect of freshwater availability, wind erosion, and;wInd born salt spray. Water held between sand particles is normally a reliable supply for tile dune plants, however, other plants must have deeply penetrating roots or live on the dune's lower slope to absorb water from ground- water zones in order to survive (26). Sand is blown from beaches to dunes and among dunes almost constantly, where 'thereJa little or no protective vegetation on the dunes, sand moves in the general direction of the prevailing winds until it encounters an obstacle sufficient In size to trap it. Tile shifting mass of dune sand provides only a pre- carious surface for plants. Wind can not only cover plants with sand but it can cause it to tear foliage, defoliate plants, reduce moisture content, and occasionally causes plants to become uprooted. As a result plants have become adapted by becoming smaller and more compact, having shorter stems, and foliage has be- ,come thinner and smaller. Plants have also been able to establish deep root systems and to form special facilities for storing moisture. Winds carrying salt spray in from the ocean also discourage plant growth. Protective coatings and rain water helps tile plants to survive in areas experiencing salt spray. Beach grass for instance has a long narrow leaf structure that reduces surface area. Bayberry has glossy wax- like leaf coatings that prevents salt absorption; the salt forms a crust and rain washes it away.Still other plants like Dusty Miller and RugoAa Rose have a tomentum characteristic. Their leaves are covered by tiny hairs causing salt crystals to form on the hair tips. With time the salt dries and falls to the ground. In general the barrier beach cotmunity is greatly influenced by tile presence or absence of the ass- ociated plant community. Inland areas are more protected and, as a result, more fully stabilized by plants. Ammophlla breviligulata, American beachgrass, plays a dominate role*in the development of coafktal vegetation communities, and performs vital functions in the stabilization of tile ephemeral barrier duties. Beach grass is beat known for Its stalks of seed heads that appear during late July or early August. American beacligrass usually starts to green-up and grow along the beaches In late March and becomes dormant by late fall. It grows in bunches containing many culms, stems, that may reach a height of two to three feet. Many new culms appear beneath tile sand in early spring. These come from the base nodes or from rhizomes that have-spread beneath the sand for several feet as seen on the next page (26,27). 63 BEACIIGRASS f Beactigrass is by far the most dominate specie associated with barrier beaches. Other dune and backdune plant species are scattered throughout-in dense clumps. Farther toward the barrier wetland a transition zone of plants occur. Here barrier beach plant species are found interspersed with those of barrier wetlands. There is no clear delineation of species in the transition zone.(illus.27) BIOTIC COMMUNITY Along with vegetation a barrier beaches aquatic and terrestrial creatures alike are subjected to un- usual stresses. Because of the stress factor barrier beaches are the least productive of ecosystems. Because there is so little opportunity for food-producing plants to exist on the beach, animal life is sup- ported by imported detritus that originates, for example, in the highly productive salt marsh ecosystem. Few animal organisms are adapteLd to the strenous sandy beach environment, though their population@may be high where-Abreachways exist. Most beach animals are filter or deposit feeders that must live below the S9 dWMA IVJM4 -ArfU WW @9W oil riol surface of the sand, extending their siphons and tentacle plumes Into the flooding tidewaters for feeding. Crabs also emerge from their burrows on the incoming tide to search for food. Beach fleas, flies, crabs,; and beetles feed along the high tide line where detrittis is left by retreating water. Many shore-birds feed at the waters edge and the backdunes serve as nesting grounds. Eventhough barrier beaches aren't highly productive ecological systems the biologic communities they serve are an integral part of the system. Therefore, it important to understand the potential impacts and effects of alteration to these zones. Beach and dune organisms are especially sensitive to disturbance by vehicular and pedestrian traffic. Nesting birds are put tinder stress by traffic. Nests are sometimes des- troyed, particularly those of terns, which prefer the more open lower beach where traffic is the heaviest (14,16). AESTHETIC ENVIRONMENT The aesthetic quality of Rhode Islands barrier beaches is based on the unity of landform and water. Upland along the dune ridge and 'on backdune areas vegetation Is another aesthetic attribute. The aesthetic environment offers !Lniq!le varie-ty and vividness. Variety is seen ohd vividness is perceived as a strong, clear impression on the senses. Variety and vividness are derived from terrain pattern, presence of water, weather characteristics, vegetatiofial pattern, and cultural land use patterns. Uniqueness Is derived from the composition of form, space, color, and texture. The beach is a palette for ever-changing textures and formations. The dunes give a scale to the beach that is often times lost by the great expanse of ocean. Dunes paralleling the beach create visual barriers that hold back views inland. When on the beach side of the dunes one cannot help but feeling a part of the barrier beach environment. It is a feeling unique in itself. When cultural elements are seen behind dune ridges from the beach this Oe@rception becomes less fulfilling.and distorted. In a way the presence of cultural objects begin to break down the unity of the natural landscape and adversely affect the sense of place. The ocean water that flows onto the beach with every new wave brings the two elements of land, or beach in this case, and water together into a unified environment. Wind, petcipitation, tides, and waves are the elements that offer variety and provide this environment with a unique vivid quality. This unique vivid quality provides fot a fulfilling visual and mental experience. Vividness can also be produced Jor instance, by a sailboat beln@ powered by the natural force of wind sailing offshore. This cultural element becomes a part of Lite environment and is subordinate within it as opposed to a dominant static house that Is visually experienced as a dominate object In this barrier beach environment. 1'his same house, however,, could of become subordinate if careful attention was given to scale, form, texture, and color. The dune and backdune landscape offer a different visual experience. Unlike the beach setting, one becomes more a part of the land environment instead of the water. Homogeniously spreading vegetation, gently sloping topography, water, and cultural influences are all a part of the composition. Within Many backduie environments along the shore dominate cultural influences physically and visually degrade the landscape. Title visual and physical degradation of this backdune landscape intensifies with every new cultural change. It is a fact that buildings on barrier beaches are degrading to the landscape. In the last decade Rhode Islanders and others have moved at an increasing rate to coastal locations.Previously the risk of occupying these flood hazard zones was avoided since the ocean periodically reclaims Its right of passage taking costly human life and property Investments. The National Flood Insurance Program, however, has en- couraged people to risk building in these hazardous areas. This does not happen without stipulation. The state and federal restrictions cause these buildings to degrade the environment that they are out to protect. These highly elevated buildings, often termed houses, become dominate and can 'be seen forilong distances. Their height creates high visual contrast and often times conflicts with the natural topography and existing vegetation. When buildings become lowered and cleverly placed in the landscape they become subordi 'nate and no longer visually degrade the landscape within the.barrier beach setting. Doing so enables the viewer to feel more apart of the natural environment and less apart of the Impeding cultural world in these natural settings (illus-33). 67 EXISTING.. PROPOSED SOLUr FIONS Wind and water erosion occurs throughout the barrier beach environment because of natural and cultural forces working t6gether and individually. The easily erodeable dunes are of primary concern sinde they -o' absorb the shock of storm waves and help to:shield land and human habitations from flooding tides and flood- Ing-. Paradoxically, they also are vulnerable to seemtngly.harmless activities. Even a footpath worn across a dune can have cummulative effects to that area; leading to a large leveled area. Plants are destroyed and the sand is left bare to the wind.and erosi@ei:occurs. When erosion occurs over an extended period a "Blow- out"results. A blowout is characterized by negative space in:the dune usually large in width. This process is liable'to continue and whole stretches of dune may be lost and landward areas they once shielded are left open to the sea. Footpaths and motorized vehicles must be localized and not extend aimlessly through the dunes (illus.28). The guiding principal is to preserve and protect dune grass especially on sites where'they are most susceptable to destruction. Increased use should be designed for on both public and private property (illus.29 and 30). Barrier beach management amounts to foresight and practical care wherever possible. This foresight should promote and hold these important beach and dune forms over a long period. Beach fencing has become an accepted and integral part of erosion abatement along Rhode Island barrier beaches and others nationwide. There is no proof that they are physically degrading, and they have been used on beaches for so long they apoear to be an integral part of the coastal landscape. Their function and best accepted implementation procedures are outlined in (illus.31). Where a dune "blowout" occurs hay bales can be staked along the blown out area (illus.32). This method has proven effective In Rhode Island, and the accumulation rate is faster than that of beach fencing. Also, with storms the bales breakdown and do not become a hazard. The use of Christmas trees for blowout construc- tion and dune building has become widespread. Although, during storms these trees can cause adverse effects when they are hurdled about by waves and wind. They also cause Increased erosion in their adjacent vicinity. The use of Christmas trees should be discouraged. Another cause of sand erosion on barrier beaches Is constrOction. During this time dune and backdune zones should be protected from alteration. The best way to do this would be to keep all construction acti-@@ vity within a pre-determtned zone with respect to naturally occurtrig landform and vegetation. In the case of sewage disposal units only the specific disposal site and immediate access to that site should be permitted. Af ter installation of the disposal system a cover of planted beacligrass is recommended to anchor the sand from blowing winds (illus.33). Any other non-vegetation material could be visually degrading. In addition to planting beacligrass within the barrier beach environment not only will they provide pro- tection from erosion, but they also can provide a natural buffer between private and public properties. It is recommended to use low profile plants that allow salt-sprays, storm waters, and wind to pass over them. These low shruba occur in the dune and backdune zones and are assumed to be the best adapted to these envi- ronments. Indigenous plant species should be used since they are the beat adapted plants for these harsh conditions. The planting procedure for these areas is done much the same way as other locations. However, it is important to add an adequate amount of moisture retaining soil to provide organic nutrients and to allow plants to become established. Ground covers should be planted to protect the soil from baking plant roots and moisture loss. Since moisture holding soils also allow salt to accumulate an acidifying fertil- izer should be used-to lower the alkalinity. If possible.frequent watering will also help to remove salts from the soil (28). For a listing of plants beat adapted for barrier beach planting refer to page (109). 69 A(,H p r JM V2 F"rP Pf ROW AWAY !2AHV- (MY-?W V( W,6tU(,flOH Of RU 6KAb-,5 rKOM VWIM4 f [TVP5fFIAM F V, IOW PrJV M. WAVf6 Arf, AM fO 'Or-]Mfr- W r,@? A 5 A V 28. @5HOIJIV rc:l @@Ljw P LV- A@ R-JU, -MOW @AJW \.*i"6 .6 k HlkjIHMr4w WVfH - 12 RAMJKJA,f@ rAwl"6-. HH lakp [/)NWI rWAA @NH)l Vol V@Y "M i@4 rcw fo I@Xlwp -fHray--,H @Aprb L-2f Wcw-- \,AfH A Kf-Uf M-[Wrr-,H to - TOP il V-5 IrwIl -7--Mf fc?. !@Mljzr- rMH 31 mw p IM @5fAU rmvvr, wit-- ran taww mfum- wwn WCfl m np fo loq-va- w Of RMth. MOW .@)Ivr, or Pmr, nowovf X \hs. -1 32. HI&H WVAKP co r1cop ATP& e44 AtPvf- mmm 4 mvrlt_ [Yrlr- or 57. ffAtH 6M5 ft9 U, _7 OX r, [MH it; M114. fo 614M , ry-cvj- OH 1@- -4 Ell - I "@Wf WHP M- WAIV-P A HIHNLTI 33. BEACH GRASS ES"IrABLISHMENT I'lie earliest recorded dune grass installation In the northeast was started about 1903, on Cape Cod. Its purpose was to reclaim areas of drifting sand where beacligrass had been depleted.The establishment of beach- grass to stabilize sand dunes has become a widely accepted practice. Extensive revegetation has taken place along the eastern seaboard as well as southern Gulf coast. In R. I.Pand other parts of New England American beacligrass, Ammophila breviligulata,id:the primary specie used. Although with the introduction of beacligrass from other places the introduction of disease is very likely. Therefore, a diversified plant species to stab- ilize dunes ig becoming essential. To date no other species have been found to adapt as well as Ammophila breviligulata. The effectiveness of establishing plantings for the various purposes of dune building and stabilization usually depends upon the methods of doing the following (29): a.The selection and procurement without to much difficulty or expense. b.The arrangement of the plantings which will. aid and maintain the development of topographic forms. c.The methods of planting and care of the plantings to promote the vegetation and forms of dunes required. PROCUREMENT Ultimately the best way to acquire beachgrass is to do selective and proper thinning of existing plants, The prerequisite for this procedure is having the proper knowledge. If the correct procedure is not followed the destructi6n of existing plants is almost guaranteed. Therefore, the safest way to obtain beach- grass,'in quantity, would 7je to purchase it from commercial nurseries. Beachgrass is ordered in culms. Culms are bunches of grass with several stems. Generally 3,000 culms are enough to plant an'area of about 2,000 square feet (28). A list of local commercial outlets can be obtained from the state Division of Fish and Wildlife. In areas requiring extensive stabilization seeding can be done for propagation directly onto the site. However, this method is not as effective as the use of transplants because of the slow rate of growth, and in most cases cover is desired immediately. ARRANGEMENT The arrangement of the plants f6v dune formation and early stabilization should be related to the over- all cliaracter of the beach arba. Generally, the area sliould be planted nearly uniformly so as to prevent the final vegetation from becoming of unequal density at different places, because an Irregular cover promotes erosion between areas of greater plant density. Planting in rows Is not as good as random arrangement, because rows tend to funnel winds, but rows cannot be avoided at times If planting machinery Is used. If sand fencing is used to start the dune formation, the design of fences determines the design of the plant- ings. Planting without fencing or hay-bales to aid deposition and stabilization is not recommended. Planting where some wind deposition Is occuring is recominended, although If this Is not the @@ase then planting should be limited to the top of dune and backdune areas. PJANTING I-For dune establishment the zone of planting should be as wide as the dune ridge to be developed, so as to assure its development. 2-Planting times for best results are from October 15 through April. At this time the Sand is moist,temp- eratures are cool, and most culms are dormant. Summer planting should be avoided, although at that time the rate of survival may be improved by watering. 3-After culms have been purchased dead leaves and underground stems that can Interfere with planting should be removed. The culms may be clipped to a length of about 18 incites from the base to reduce bulk and to make planting easier. 4-All culms should be kept cool and moist and planted as soon as possible. The basal, or base, portion where new growth will develop, must be protected from drying out. This should be done by packing Elie culms tightly together or by covdring the basal portions with ihoist burlap or sand. While planting, culms can be carried efficiently in a pall containing a few incites of water. 5-The first object to planting is to place culms.close enough to assure a sufficient mass of underground parts. The mass of both underground and aerial parts will cause sufficient build-up and stabilization around the plantings. Clumps of three should be planted in one pit. Spacing should be 12" on active dune tops, 12"-18" on backdunes, and 24" for non-active areas (illus.34). Culms should be planted at a depth of 7"-9" from the base of the plant. 6-Within a few minutes after planting the pit should be backfilled with existing sand and firmed with the foot, not firmly packed. 77 FERTILIZATION After planting fertilizer should be used to establish beach grass faster than natural conditions. Fertilizer can increase the plants height and encourage it to grow into unprotected areas. Fertilizer should be applied either all at once in April or May, the beginning of the beacligrasses growing season, or It can be applied at once and again in July. If fertilizer is applied during two differ- ent months then the amount should be cut in half. As a general rule, planting done from July through Sept. should be fertilized Immediately after planting. Those planted after Sept. should be fertilized in April. On small areas broadcasting can be done by hand, and machinery can efficiently spread It on larger areas. Inorganic fertilizers, high in nitrogen, are the most effective and least expensive to use.Granular ones such as 10-10-10, and ecetera are satisfactory. The first number indicates the percentage of nitrogen. The rate of application is 2-3lbs. per 1,000s.f. for two years. After this,fertilizer can be used to maintain a healthy stand (28,29). VUH@ "fikok ., - VUHr, MR? 1.5'-Z4* [Mf WIH6 OH "r- 9fA" AKrA,12- Z-.fl r FK @@jH@A PfAKF- W PH ;ZfOM V ArKll- .5 'ulw? fo rf- rmfP ffK _wv fo ff- firmi-Y pty-W 4"p am@? -ro Amiw- MP WHMAJ@, Air, 7IT or lo-lo-lo rfrillW lkw m @)Pvp ovw W44 WF-P Apt)@. PrI p rFbDlf@-,> qT-V\P -501-4 IW A M Eo7o IH IL)[,-f [Or W@W/ mwf BEACHES BEACHES In Rhode Island several beach types exist along the shorelines of Narragansett Bay,,t:lie Sakonnet River, and outside their proper limits. Beaches along unprotected southern coastline are the most physl- cally stressed, and consequently the least productive of coastal ecosystems. Unlike the more sheltered beaches of the upper Bay, these areas are exposed to ocean swells and currents. Beaches are highly variable landforme consisting of unconsolidated materials eroded from land based geologic formations. Waves and currents are continually at work changing the physiographic form and geo- logic composition. This constant alteration of beach forms within the littoral zone make these sites un- suitable for permanent structures. Beaches In Rhode Island are characterized by their particle size of sediments, wave and current action, and their associated landforms directly inland.(6). PHYSIOGRAPHY .. GEOLOGY The physlographic and geologic form of beaches and their Inland features are aresult of past geolog- I.c action and more recent weathering processes. Typically, beaches are delineated by an Inland rise In topography, or.slope, when eroded is termed a scarp or escarpment (illus.35). These slopes and scarps range in height from 3ft. to 40ft.. Eventhough a beach may be temporarily eroded by storm waves, and later partly or wholly restored by swells, erosion and accretion patterns may occur seasonally.(Illus.36). The long-range condition of a beach, whether eroding, stable, or accreting depends on the,rates of supply and losses of littoral sediments. The shore increases in size when the rate of supply exceeds the rate of loss. The beach Is considered stable, eventhough subject to storm and seasonal change, when the rates of supply and loss are equal. Since the physlographIc form of beachea Is determIned by Its geology beacbes can be characterized as steep or gently sloping. Generally the larger the sand particles which make up *the beach, the steeper. the beach will be. Beaches with gently sloping foreshores and backshore zones usually have an accumulation of the finer or smaller sizes of sand. The height and angle of a backshore slope or scarp is also determined by its surficial and under- lying geology. When the slope becomes eroded the sediments are transported by runoff to the beach where, with time, are transferred by waves and currents along the shoreline to nourish other eroded beaches. 80 -A4 I'v No by @NOV 04,11 V@qol HIM ff-,cAp mp rw m".H PDr--IH6- [Od WAVV.- rWW>Y MHW I fililli'MMMEMI IN R) IK16-, H16H WAW FW6Y p WA R) C".,U 36. SOILS. The lower slopes and scarps backing beaches generally consist of glacial outwash and till. The lower slopes consisting of outwash range from 3ft. to 20ft. in height, whereas the taller ones, consisting pri- marily of till, range from 10ft. to 40ft.. This outwash consists of scirted gravel, sand, and finnite interlayered zones of silt and clay. The till Is characterized more by its' boulders and cobbles, and clay, although it does contain quantities of sand and gravel. Till is found directly over bedrock. For the most part, where vegetation exists and the weathering process has taken place ther exists a soil layer known as the solum. This solum is a cover found over till or outwash or both. SOLUM PARENT MATERIAL A&VP BEDROCK Where both outwash and till have been stripped bare of vegetation, these soils have taken on their natural angle of repose. Since outwash Is fairly consistent In size ahd shape the angle Is normally con- stant. Till Is composed of sediments varied in size atid shape and therefore, its degree of slope is often varied throughout the slope and often times steep in locations (Illus.37). Beaches contain eroded soils and consist primarily of sorted sand, pebbles, cobbles, and boulders. The most common beach types are sand, sand with pebble, and sand with cobble.The width varies with locat- ion. All of these beaches have great capillary action that allows water to pass through rapidly. The finer grained sediments become more or less saturated by a filut of water in the tidal zone. This retention HY OUfV@Mll 5-20'/ 5:1 V I Lf-f,, MONO WAW WWff f"ON 10-35'/ 2:1 Illy1w pw6NY MM HlIr 3 7" WNW V t.oOo' .4 @@ UN 38@ of water cushions the beach and reduces wearing action by waves and the beach becomes relatively flat. Where larger more coarse sands are prevelent the accretion and wearing action by. waves and currents, if present, occurs more rapidly (6). There are two types of stability failure on steep slopes. The first, slippage, Involves a circular movement In section of the entire slope, or of a portion, that results In the falling of material'to a lower angle of repose and causes the toe of the slope or immediate area to be pushed forward. This norm- ally results when the soil has been weakened by pressure or If it becomes saturated with water and becomes tooheavy. This can occur from on the slope or from waves eating away at the slope toe. The second type of failure involves the surface of the slope, where the surface is subject to surface erosion by precipita- Llon (illus.37). Fresh-water runoff can be greatly accelerated by Increased levels of subsurface satura- tion. This zone of saturation Is most critical on an exposed slope witen pressure forces the water to flow out near the base. This water can carr@ sediments with it and cause slope stabUlty (23). HYDROLOGY The beach, slope, and scarp topography are constantly under physical stress from waves and currents, runoff from the land. The more sheltered beaches are mainly subjected to runoff and at times storni waves and currents, whereas the more exposed beaches are subject to constant forces of waves and currents front Lite ocean. Concurrently, the more exposed beaches are undergoing constant change.This is only noticed by the casual observer during storms or other periods of Increased hydrological stress. VEGETATION Plant life is sparse on the physically stressed beaches. Itere It Is difficult for the plants to find anchorage. If stable long enough plants are able to secure themselves to the face of a scarp. On.less physically stressed beaches plant life has grown within the backshore zone and on the lower to upper portions of the slope.This vegetation receives Its water and chemical nutrients from .ground water that is supplied from stored quantities, and from that which has been stored in more surft- cial zones beneath the surface. Plants living on the backshore and lower slope receive an abundance of water since they are In the transition zone where salt water meets freshwater. Plants that exist on the drier sections of the slope are there because they have adapted themselves to these often streno"s cond- itions. There are several plant communities that find their way to the coastal beach edge. A list of the atore dominate species is on pp. 104-109. Naturally occuring vegetation plays a very important role In 86 maintaining slope stability and providing a chemical nutrient balance for the optimum functioning of biological processes within the beach and associated environments (26). BIOTIC COMMUNIT'i Stress factors are also experienced by animals that live within the beach environment. It is the foreshore and tidal zones where life abounds. t-_4 BEACH COMMNlTY The rocky shore represents one extreme of the intertidal habit and the sandy beach represents the other. Where beaches of unstable pebbles exist life is usually barren. Life on sandy beaches does not experience violent fluctuations in temperature as do those on rocky shores. The animals living on cobble shores require protection from sunlight, dessication, and violent water movements, therefore they have made their homes in the mud that has been trapped beneath the cobbles. The faunal community depends upon the stability of the.cobbles. If they are easily overturned by waves, the populations beneath will die from exposure. If rock movement is greatest in the winter, when waves are intensif ied, then the summer population: will. consist largely of summer annuals. The animals of the higher surface zone of the shore are able to endure the periods of exposure to the drying action of wind, sun and summer heat, low salinity during rainstorms, and the scouring of winter ice flows. Cradled within and growing on the face of water-worn boulders and cobbles, animal and plant organisms adapt to zones that meet their respective sensitivity to tidal exposure. Larger forms of algae play a dominant role in the p-roductivity of the rocky shore ecosystem. They can be.seen at a variety of elevations within and 'below the intertidal zone. These complex algae have no roots or rigid steins but fasten themselves to the rock- face with structures called holdfasts. Observation of the rocky shore community from the zone above the high spring tide level, the splash zone, reveals blue-green algae which leave a slippery scum on rocks and shells, and black lichens. One of the most striking aspects of rocky shore plants and animals Is .Lhat they live on a solid substrate fully exposed to Lite forces of water. There Is no opportunity to maneuver for living space above or below the surface as do organisms of sand and mud fl.aL communities. Many of Lite plants and animals are long-lived and permanently anchored. Compared to other ecosystems, rocky shore animal populations exhibit less annual or seasonal change in numbers. Also, unlike other coastal ecosystems, rocky shore communities use or retain very small quantities of nutrients they produce.Where there is much tidal and wave energy released against the rocky shore, mucit of the food material produced by plants and animals Is carried away as detr1tus and becomes part of the food chain for fish, crustaceans, and molluscs found In the open water or on nearby tidal flats and sand beaches (14,30). ,Unlike cobble and boulder beaches, life on sand beaches is subjected to continual movement from waves, tides, and wind. The sandy shore at low tide appears barren of life alth6ugh beneath Lite sand, life exists waiting for the next high tide. Eventhough the surface temperature of sand at mtdday may be 50 degrees F higher than Lite returning sea-water, the temperature a few incites below the surface remains almost constant throughout the year. Nor Is there a violent fluctuation In salinity, even johen fresh water runs over the surface of the sand.. Below 10 incites, salinity is little effected. Organic matter accumulates within Lite sand, especially in sheltered areas. This detritus offers food for some Inhabitants of the sandy beach, but where It accum-'. ulates in large quantities, it prevents the free circulation of water,and anaerobic bacteria form a black zone resulting from oxygen deficiency. Most animals of the sandy beach either occupy permanent or semipermanent tubes within the sand, or they can burrow rapidly Into the sand when they need to do so. Except for a few beach hoppers and a few plant-feeding insects, the true sand dwellers feed on detritus. For this reason sandy shores containing the greater amounts of organic matter support more life. Whether hidden beneath the sAnd or exposed on the rocks, all forms of life along the waters edge of the shoreline has adapted remarkably well to the rise and fall of tides.Their survival Is essential (14,30). AESTHETIC ENVIRONMENT The aesthetic quality of Rhode Island beaches is based on the unity of landform, water, and vegetation. Each coastal system offers unique variety and vividness. Variety is seen and vividness Is perceived as a strong,clear Impression on the senses. Variety and vividness itre derived from terrain patterns, presence of water, weather characteristics, vegetational pattern, and cultural land use patterns. Uniqueness is derived from the composition of form, space,. color, and texture. When naturally occuring vegetation exists on a slope or scarp, there is no need for aesthetic judge- ment. These natural features exist because they serve a function within the landscape and natural. world. This, however, forms the basis for aesthetic evaluation. When cultural elements have been intr6duced into and onto these beach areas then aesthetic evaluatlon is warranted. The degree of degradation would depend on the cultural items composition in contrast with that of the beach and adjacent area and the quantity bf the particular item. For example, where a plastic item is prevelent on a beach this zone Is considered visually degraded. The degree of degredation depends on the composition of the plastic. Along developed shorelines views onto beaches from adjacent areas are often focused on the edge where land meets beach because it is here a strong focal point exists due to alteration of the otherwise natural area. Normally, the focal point is on the edge where water meets beach in the natural i:cdlturally undis- turbed landscape. This altered edge can be evaluated aesthetically by examining the natural features and comparing their composition with that of the altered edge. For example, if a beach consisted of cobbles and rip-rap had been installed it wouldbe less visually degrading than if cobbles were used as opposed to concrete. Since natural vegetation exists on both sides of the property then this would be rated as a high degree of degradation as seen in the following illustration. V RIP RAP.. VISUAL. DEGRADATION EXISTING.. PROPOSED SOLUTIONS Increased erosion rates on beaches and their bordering slopes Is primarily caused by human alteration. In the past groins have been placed perpendicular to a beach shoreline to trap littoral drift or to retard erosion of the shore. This is done to afford protection to the adjoining backshore, however, groins deprive downshore areas of deposition and the rate of erosion is greater than accretion In the downshore zone (illus.39). This type of erosion should become obsolete If it hasn't already. A less degrading method of building beaches Is to deposit sediment on the updrift side of eroded area and let the longshore cur- rents transport the sand to the area to be restored. This method has been done in Florida on several occasions and has proven effective for an extended period of time. The most important aspect of this beach restoration is to choose sediment that is closely characteristic to that of the extsting without having to use another beach as a borrow site. Inland from the beach, Is where the concernable erosion takes place. For the most part people bring on their own erosion problems by altering the slope in some manner. The following slope protection measures should be followed: -A setback line,pg.41, should be used during construction. -Deposition of foreig n matter onto slope should be prohibited. -Foot traffic and other increased weight should be kept off of slope. -Slopes should not be left bare of vegetation when the chance of erosion prevails. Revetments are another typical structural solution to erosion abatement on si.opes. Fortunately instal- lation costs are astronomical. or their degradation would have become more widespread by this time. Revet- ments are negative features when used along the coastline, they accelerate erosion on adjacent beaches where moderate and high wave energy is present (Illus.40). Their use should be restricted. In order to best simulate natural processes, that are more likely to be effective and less degrading, other measures have been formulated and should be chosen from a wide range of options. 90 WGIKJ - R.- .1141, doull-An 39. mv c fVWMMfb 1,5 ActrPPP Tfit' W4"lkl WWI ft-v@ 4fPw do-@ay 6INL)LAX MA5 W"rfrl fHq m"v MV 1@ HI&MY PPMqfV Wlc,. 0 m Mcf-F, ff ro 1, kK- Vr6qqW AM'b 114q AVOIP iMpr"qf 0 For- -Hal W-5 f fo rmltq- PrI itAul5por-f rip-rAr VO!510M 40, TREATMENT OF SLOPE TENDING TO SLIP PROBLEM: Lack of subsurface stability. SOLUTION: 1) Use of bubgrade baffles to retain.and support soil and to--maintain visual quality. 2) Establish vegetation for utilization of roots to anchor soil. PROBLEM: Weight at top of slope. SOLUTION: 1) Reduce angle of slope. (illus.42) 2) Create dual slope gradients. (illus.42) TREATMENT OF SLOPE SURFACE PROBLEM: Runoff causing erosion. SOLUTION: 1) Avoid damage to vegetation. 2) Consider and evaluate flow redirection. 3) Establish vegetation. 4) Terracing of slope. 5) Brusbwood matt. (illus.43) 6) Hay/straw matt. (illus.43) 7) Jute matt. (illus.43) The aforementioned solutions,and those previously stated in earlier sections,can be adapted to I specific uses individually and jointly for effective slope stabilization. For allisting of plants best suited for slopq planting refer to pages (104-108). rv PPmv gwr@, for vw-hma All 614r tq@ PArW 0 1?4@ wpbm)clf6v Or @f v wlmr-. VillmNowb Ap@ L)pw Ow -@)@ 6 0 VrWfAflOO fO M Uf"tllW 19" r"Q*v M-- I DYKf-b CA" im -bn@ffl VM61 /\I,frmklr- womv M fo PgTO6 PrWf '14@ 9@wt PHU Kut) VA -Y r \@Iouv 94 41, aL 12 5">5011" lypo 2. rpm llul @, KV; MAlffk, lbot, k IF. mv--@-w wwlvl MAOK.- v fwo 42. V, VP Off fo @y Wv y v "MH W* Kai PM1 or M- I A PIA AA, rim lot xkqnw 0 5. V1. PIULTI-1 00 @bwp V--) Dbw Pr 6-plWzkrIw 0 Or "P "cbVV PJ)Wff. WHIV, ow 16 awjj1K1c> pf@4 10 brf -b-@ 6ONNbf Or fv@&b f OR pe 6F-W 66rtt 11:5MM6 No [,#&prr fHM k 00. P. - I Apo" o14 IM)AWWAVY W11H MUM- Al@ 60 WFW6 6HODW M @@ IWX 1*6 dxpl@ \M-4 Wir WRA@ -1119 @fA V"f, AMQ0fijY, OG H 0 6 )w It) ODw lb MM4"y L PIZ- @J=b"Aom- HM, A tHMCr-- cf W-01M FIP T pa& 01@ k*AW itrOw ff, PKLY 6tw- 56PVW,5Hr1?- Lyt-r, LGCX- ppflf @Mo- 4- 96 SITE SPECIFIC DESIGN I RHODE ISLAND #101.6j"." 1-- 6 [O@AfJOM WAPWICK Klr(/K ILL- Af. tl I I-- Bowe seemn" HY r W051 W M MAf- Hm caup 2v -zam *N55 W fH Ho capf4 60" A [W @AF6@, fOp 6f COT@@ I W/ k`x WUJP WAn vr& "I "MW105 qrlw m wx@ PF -.-Pi O@b WHM HP\6 r" pootl- W-, V- WP 5 - U1 WAJ@r oxr w oulf if owww wAwb fig air,, MPM fopr 61W Hm 15 Nf-" 16 wmqw f F@, lb wwv-) I" MUPIAJ jWWTX- HUHMP YVb. WAb "AM& f lb I, I utmulv f6 r4y clv@ 60 @MVW 6pm it/ or . aj wAb. Ml@,- LIA@r WA5 l4w Pill- wbr 6YU "A 4 @o Wry vi 1,5 oof fklr, bwpo lop5f I I vll@ WOOV" 45 IWP ll@lop HW@@ Vlewl@r F@ow, H@- -@tpp- a7 M, 1.9@*fiolAb Vib f A fo o bl P 1,5 bW OP- wi H JHP PPMAI@6- WOP OP CW P" cf VpflOM15. A). "I. -Z-r., MUIMOMMIG-16). @AM Ab(A@ Mmovr" WK 6 .5NVVI b-wm;@frmf WNKM14 qftb. roof1wb ou 44. IM-5fAL-1- tffI mrw fo m w PrWf Of NW ZOMF,b. . PAW dAwl@, 5. &P t?Tcv--6 wILoAm. 6. 7. 6Mw AW W1 MffIH6,. @HPD or glo'xllob- WPI 6 -4*Tf, \44, AL@W m . nop rrO@AMY 1@6f@07H 6LVLV-blw To rpovipf., 4 1 6@9 pf@- 102 COASTAL VEGETATION Provided are lists of dominate indigenous plant species best adapted to Rhode Island's coastal areas. These lists were composed after conversations with biologists who frequent in the "field", with other professionals, and after extensive observations by the author of this publication. The intention of these lists is not only to provide insight, but to provide plants that can best aid erosion abatement as well as support natural functions and biotic communities. The majority of these plants are easily transplantable and can be purchased through statewide nurseries. Not listed, but equally important, are native perenials and grasses. For the most part, these species can be used as permanent ground covers or as temporary erosion controls while other plant species are becoming established. Sources Rhode Island State Department of Environmental Management JAMES PARKHURST ....Biologist, Division of Fish and Wildlife LINDA STEERE .......Biologist, Division of Fish and Wildlife CAROLYN WEYMOUTH ...Biologist, Wetlands Section Dirr, M. 1977. "Manual of Woody Landscape Plants." Stipes Pub. Co. N.Y. State College Ag. Dept. 1962, "Plants for New York Seashores." Cornell ext. bull. 1023. SCS. 1978. "Conservation Plants for R.I." Rhode Island SCS. 1980. "Sediment and Erosion Control Handbook." Rhode Island Viertel, A. 1976, "Trees, Shrubs and Vines." Syracuse Univ. Press Wyman, D. 1971. "Gardening Encyclopedia." Macmillan Pub. Co. C UASTAL WETLANDS BARRIER WETLANDS REACHES GROUND COVER wTAHICAL NAME TOLERATES SOIL TYPICAL HEIGHT CROWTH FRUIT COMMON NAME SHADE, malmomr/WET FFET / WIDTH RATE Arctostlphyl.os tiva urni Partial 1) 6-12 2-4 Slow Red bearberry 1/4 Inch Cal-Itina vulgarls Partial D H 1-2 2 Slow scotch heather 1) M W Very Red CeIastrtis scandenq Partial 10-20 American bittersweet Fast 1/4 Inch Loid-cern japontca Partial D M 15-20 Very Black Japanese laomysuckle Fast 1/4 Inch Parthenocissits quinquefolla Yes D M 15-20 Very Black Virginia creeper Fast 1/4 inch R11119 radicang Yes 1) M W 15-20 Very poison Ivy Fast V11its lambrusen Yes D M 20-30 Very Black wLld grape Fast 1/2 inch Comptotila Iferegrina No D 2-4 2-4 Slow Ned. COASTAL WETLANDS BARRIER WETLANDS BEACHES SHRUBS BOTANICAL NAME TOLERATES SOIL TYPICAL HEIGHT GROWTH FRUIT COMMON NMIE SHADE DRY/MOIST/WET FEET WIDTH RATE Rhus sp. Partial D 10-12 Fast sumac Mamnus cathartica Partial D H 10-15 Fast Black common buckthorn 1/4 Inch Rosa rugosa No D M 3-5 3-5 Med. Red rugosa. rose 1/4-1/2 Inch Rosa virgintana Yes D H 3-5 Fast Virginia rose Spirea. latifolia Partial D M 2-4 3-4 Fast Dry meadowsweet Pod Spirea tomentosa Partial D 4-5 4-5 Fast hardhack spirea Symphoricarpus albus Yes D M W 3-6 3-5 Fast White siiowberry ornamental Vaccinium corymbosum Partial D H 4-6 4-6 Slow Blue-Black highbush blueberry 3/8 inch Viburnum dentatum Partial D H 4-6 4-6 Med. Blue-Black arrowood viburnum 1/4 Inch Viburnum cassanoldes withe-rod viburnum Partial D M 4-6 4-6 Med. Blue-Black 1/4 Inch COASTAL WETLANDS BARRIER WETIANDS BEACHES SHRUB BOTANICAL NAME TOLERATES SOIL TYPICAL HEICHT GROWTH FRUIT COMMON NAME SHADE DRY/MOIST/WET FEET WIDTH RATE Amelanchler canadensis Yes M. W 6-20 Med. shadbush Aronia arbut1folla Partial D M 6-10 3-6 Med. Red red chokeberry Berberis thunbergii Yes D 3-6 3-4 Med. Red Japanese barberry Clethra. alnifolia. Yes M W 3-8 4-5 Slow Black suimnersweet 1/8 inch Cornus stolonifera. Yes M W 3-5 3-5 red osier dogwood Ilex glabra. H W 3-5 3-4 Slow Black inkberry 1/4 Inch Iva frutescens Partial M W 3-6 marsh elder Lonicera tatarica. No D M 4-8 4-6 Very Red tatarica honeysuckle Fast 1/4 inch Myrica pennsylvanica Partial D M 3-5 3-5 Fast Black bayberry Persistent Prunus maritima Partial D M 6-8 Med. Red beach plum 3/4-1 inch 105 COASTAL WETLANDS BARRIER WETLANDS BEACHES TREES BOTANICAL NAME TOLERATES SOIL TYPICAL HEICHT CROWTH FRUIT COMMON NAME SHADE DRY/MOIST/WET FEET WIDTH RATE Morus alba Partial D H 20-30 20-25 Fast Pod white mulberry Prunus americana No- D M 15-25 Fast Red American cherry Partial I inch Prunus serotina Partial D M 20-25 Med. Red black cherry 1/2 inch Pinus rigida Partial D M 15-25 Med. pitch pine Quercus sp. No- D M 30-40 Slow- Nut oak Partial Med. Salix discolor No M W 10-20 Very Catican pussy willow Fast Salix sp. No M W 30-50 Very Catican willow Fast COASTAL WETLANDS BARRIER WETLANDS BEACHES TREES BOTANICAL NAME TOLERATES SOIL TYPICAL HEIGHT GROWTH FRUIT COMMON NAME SHADE DRY/MOIST/WET FEET / WIDTH RATE Aflanthus altissima Yes D H W 45 Very Persistent tree of heaven Fast Sawara Alnus glutinosa Partial M W 12-15 Fast common alder Young Acer rubrum Yes M W 40-50 20-40 Med. red maple Fast Crataegus mollis Partial D 15-25 Very Red downy hawthorn Fast 1/2-1 inch Eleagnus angustifolia No- D H W 10-15 Very Silvery Rtissian olive Partial Fast 3/8 inch Eleagnus umbellata, No- D M 10-15 Very Red autumn olive Partial Fast 1/4 Inch Betula populifolia Yes D H 20-40 Med. gray birch Fast Juniperus virgininna No D H 20-25 Med. American red cedar Juniperus communis No D 5-10 Slow common juniper Robinia pseudoacacia No- D M 30-40 20-25 Very Persistent black locust Partial Fast Samara 107 BARRIER BEACHES All plant species adapted to the barrier beach community have become Indigenous to the slightly acid soils found along R.1 barrier beaches. All are normally below five feet in height and are best adapted to full sun. DUNE Ammophila breviligulata TRANSITION (back dune/coastal wetland American beachgrass Baccharis halimifolia Parthenocissus quinquefolia Artemisia stelleriana groundselbush Virginia creeper dusty miller Iva frutescens Suaeda maritima. Lathyrus maritimus marsh elder sea blite beach pea Juniperus communis Vitis lambrusca Solidago sempervirens common juniper wild grape seaside goldenrod BACKDUNE Aster sp. Prunus maritima aster beach plum Hudsonia ericoides Rosa rugosa beach heather rugosa rose Juniperus conferta Rosa virginiana shore juniper Virginia rose Myrica pennsylvanica bayberry Panicum capillare witch grass 109 REFERENCES 1. Boothroyd,J.&Al-Saud,A.1978. "Survey of The Susceptibility of Narrag. Bay to Erosion". Unpublished. 2. Quinn,1971. "Bedrock Geology of Rhode Island". U.S.G.S. Bulletin no.1295. 3. Ilicks,S.1972. "On Trends of Long Period Sea Level Rise." Shore & Beach,April. 4. Clark,J.1974. "Coastal Ecosystems." The Conservation Foundation. 5. Van Dorn, W. 19 74. "Oceanography and Seamanship." Dodd, Mead&Company. 6. Army Corp.1961. "Shore Protection Manual". Army Corps of Engineers. 7. American Nurserymens Assoc. "Inspection Gui'de For Landscape Planting." June 1972. 8. Spurway,C.1941. "Soil Reaction (pH) Reaction of Plants." Mich. State. Univ. April. 9. 11ackett,1972. "Landscape Development of Steep Slopes." Oriel Press, England. 10. Powell,Winter,Bodwitch,1970. "Soil Erosion and Sediment Control." U.S.C.S. 11. S.C.S. "Rhode Island Erosion Control Handbook." 1980. 12. S.C.S. "Conservation Plants For Rhode Island." 1978. 13. Balvorson,W.,Gardiner,W. "Atlas of Rhode Island Salt Marshes." U.R.I. Marime memo. no.44 1976. 14. Smith,R.1966."geology and Field Biology." Harper & Row. 15. Teal,J.&M.1969. "Life and Death of The Salt Marsh." Audobon/Ballantine 16.,Odum,E.1961."Role of Tidal Marshes In Estuarine Production." Conservationist, June-July 17. Oduni,E.1971."Fundamentals of Ecology." W.B.Saunders Co. Philadelphia 1.8. Shus ter, C. 19 76. "Nature of a Tidal Marsh." N.Y.State Conservationist, Aug.-Sept. 19. Knutson,P.1977. "Planting Guidelines For Marsh Development and Bank Stabilization." Army Corps. 20. Woodhouse,W. Seneca, E., Broome, S. 1974. "Propogation of Spartina alternifolia. For Substrate Stabilization and Salt Marsh Development." TM-46,Army Corps. 21. Garbisch,Jr.,E.1977. "Survey and Basic Guidelines For Marsh Establishment." 1977. 22. Environmental Concern,lnc.1977."Specification for Salt Marsh Establishment." St. Michaels, Md. 23. Lahee,F.1969. "Field Geology." McGraw Hill. 24. Olsen,S.1973. "Rhode Island Barrier Beaches." URI. Marine Tech. Report no. 4. 25. Goodno,R.1978. "Marine and Coastal Facts." Sea Grant Specialist. 26. Farb, P. Hay,D. 1966. "The Atlantic Shore." Harper & Row. 27. 11ank,V. "Sand Dune Stabilization on the North Atlantic Coast." Journal of Soil & Water Cons. Vol.22 28. Jagschi tz, J. Wake field, R. "How To Build and Save Beaches and Dunes." URI. Marine Leaflet, Series no.4 29. Army Corps.1954. "Dune Formation and Stabilization by Vegetation." Army Corps of Engineers, Memo.no.101. 30. Leonard,J.1972. "Atlantic Beaches." Time Life Books. 110 ILLUSTRATIONS illus. I CRMC limits of Jurisdiction pg. 6 Barrier Beach 2 Glacial outwash 9 3 Glacial till 9 24 Formation 59 4 Coastal zone nutrient exchange 11 25 Dune erosion 60 5 Wave characteristics 13 26 Peat exposed 62 6 Sediment and water movement 12 27 Vegetation 65 7 Littoral transport 16 28 Dune breaching 70 8 Hay bale detail 22 29 Increased use access 71 9 Planting for natural character 23 30 Access 72 10 Ground cover planting detail 27 31 Dune fencing 73 11 Shrub planting detail 28 32 Haybale dune building 74 12 Tree planting detail 29 33 Flood elevations and ISDS 75 34 Dune Planting 79 Coastal Wetlands Beaches 13 Physiographic and geologic form 32 14 Slope @33 35 Physiographic form 81 15 Physiographic and geologic form 34 36 Seasonal physiography 82 16 Vegetation 37 37 Soils 84 17 Vegetation destruction 43 38 Hydrology 85 18 Setback line 44 39 Groins,beacli restoration 91 19 Revetments 45 40 Revetments 92 20 Revetment problems 46 41 Baffles 94 21 Access 47 42 Slope reduction 95 22 Development suitabilities for marsh 50 43 Brushwood,hay,jute netting 96 23 Marsh plant spacing 52 The preparation of this project was financed in part by a grant from the National Oceanic and Atmospheric Administration, under the provisions of the Coastal Zone Management Act of 1972 (Public Law 92-583), through the Integrated Grant Administration program as a part of Federal Regional Council grant FRC-JF-01-11. NOAA COASTAL SERVICES CENTER LIBRARY 3 6668 14109 0607