Beach Nourishment and Protection (1995)

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APPENDIX D Design of Beach Nourishment Projects INTRODUCTION A beach that is under consideration for nourishment typically will have eroded over an extended period, so that its storm protection and recreational potential have been substantially reduced. The objectives of beach nourishment are to improve shore protection and recreational opportunities. The design pro- cess for beach nourishment projects determines the quantity, configuration, and distribution of the sediment to be placed along a specific section of coast in order to restore natural storm protection, recreational area, or both. The design objec- tive is to identify a unique project that best addresses and accommodates site conditions, erosion rates, wave climate, available sand, costs, funding sources, and environmental considerations. The design must consider long-term erosion and storm impacts to assess the appropriate nourishment quantity, quality, and placement along the shore. As a rule of thumb, the nourished beach can be expected to erode at least as fast as the prenourished shoreline. Therefore, an allowance for continued erosion of beach fill is also part of the design assess- ment. Further, the combination of higher tides and waves during storm conditions can erode the upper beach and directly impact upland areas, causing damage and failure of structures. Thus, reducing the vulnerability of coastal structures to storm damage is also an important design consideration. Each nourishment project has unique environmental and economic condi- tions that affect the design process. The beach nourishment project ought to be of sufficient size to provide a financially feasible level of protection to the upland structures. Impacts to sensitive nearshore or offshore environments should be 189

190 BEACH NOURISHMENT AND PROTECTION minimized to the extent possible. The following defines the beach nourishment formulation processes. Design is the process of solving problems or achieving a desired objective or objectives by: · proposing one or more alternative solutions; · evaluating those solutions in view of physical, economic, environmental. and other constraints; · adopting or adapting elements of the best alternatives; and · formulating the solution that best meets the desired objective or objec tives. Good design is an iterative process that requires attention to details. Beach nour- ishment design involves selecting the project's length, beach profile cross- section, dune height, use of structures for erosion control, sediment characteris- tics, and borrow source. Analysis is an important tool by which various designs or elements of a design can be objectively evaluated. For beach nourishment, analysis brings knowledge of coastal processes to bear on the evaluation of alternative designs. Analytical and numerical models of alongshore sand transport and cross-shore transport are examples of coastal process models that are important in beach nourishment project analysis. Judgment is also needed in evaluating candidate designs or elements of a design because coastal processes are complex (NRC, 1987, 1989, 1990, 1992) and design methodologies are constantly evolving. Judgment, however, is not totally objective because it depends on a designer's experience. Different design- ers may interpret objectives and constraints differently. Therefore, no two de- signers approach a problem in exactly the same way and, in general, will not arrive at identical designs. There are always trade-offs, and judgment is the factor that selects from among those trade-offs where no quantitative analytic proce- dures or criteria exist. Because judgment is not objective, design review is an important element of the process. Design review brings the experience and judg- ment of a number of designers to bear on a problem. The criterion for evaluating a design is how well it achieves the desired objectives within the given con- straints. For beach nourishment, project objectives usually include protecting backbeach areas from waves and flooding damage and providing a beach for recreational purposes. Where sea turtles nest on coastal beaches, replacing sea- walls with nourished beaches can reestablish nesting habitat. Public participation is important throughout the design process for any pub- lic works project such as beach nourishment, initially to ensure that objectives and constraints are clearly defined and later to ensure that the original objectives are still valid and have been met within the given constraints.

APPENDIX D 191 DESIGN HISTORY The design process has evolved over time from the first project design on Coney Island in 1922 (Farley, 1923; Davison et al., 1992; Dornhelm, 1995) to the latest computer-aided designs of nourishment at Ocean City, Maryland (Hanson and Byrnes, 1991), and the third periodic nourishment at Delray Beach, Florida (Coastal Planning and Engineering, 1992a). Since the early 1950s, the scientific basis for beach nourishment project design has increased significantly. Although some of the early projects used finer bay and lagoon sediments, which performed poorly, later projects used coarser offshore sand with more favorable results (Davison et al., 1992~. The evolution of the design process at Wrightsville Beach, North Carolina, demonstrates the changing nature of the design process. The early design cross- section placed sand primarily on the nearshore profile without consideration for building the offshore portion of the profile. The dry beach quickly adjusted to flatter natural slopes when sand moved offshore. The later renourishment designs for Wrightsville Beach provided enough fill for the entire active profile; the offshore movement of sand was properly anticipated. Hall (1952) documents 72 beach nourishment projects constructed in the United States between 1922 and 1950. Most were in New York, New Jersey, and Southern California. He also discusses design parameters and needs for further development of established source requirements and the quality of borrow mate- rials. Krumbein (1957) published the first papers that dealt with grain size as a design factor for nourished beaches. Later work by Krumbein and James (1965), James (1974, 1975), and Dean (1974) further developed the concepts of native beach sand as.a hydraulically stable population from which performance of a borrow material with dissimilar grain sizes can be compared. The work of James (1974, 1975) has been incorporated into the standard practices of the U.S. Army Corps of Engineers (USAGE, 1984~. These practices are based on (1) the overfill factor, RAP which predicts how much fill will remain after sorting by hydrody- namic processes, and (2) the renourishment factor, RI, which predicts how much nourishment will be necessary when compared with the performance of native sand (Davison et al., 1992~. Early nourishment projects did not consider the offshore profile properly, often using unrealistic slopes, which subsequently caused an excessive loss of subaerial (dry) beach (Vallianos, 1974; Jarrett 1987; Hanson and Lillycrop, 1988; Davison et al., 19921. Hallermeier (1981a, b) developed donations of the active profile based on wave parameters. Two limiting depths were defined. One of them, dL, is the maximum water depth for sand erosion and seaward transport by an extreme yearly wave condition and corresponds to the seaward limit of appre- ciable seasonal profile change. The second is the maximum water depth for sand motion (on a flat bed) by median wave conditions and corresponds to the seaward

92 BEACHNOURISHMENT AND PROTECTION limit of the constructed wave profile. Hallermeier suggested that do be used as the basis of beach nourishment design; later analysis showed field observations sup- porting this recommendation (Houston, 1991a; Hands, l991J. Birkemeier (1985) refined the seaward limit of profile change. His results were based on more accurate surveys at Duck, North Carolina. Dean (1983, 1991) proposed the use of equilibrium profile concepts for beach nourishment design. He suggested that the shape of the offshore profile can be approximated by a shape described as follows: h(y' = Ay067 (D-1) where hays is the depth at distance (y) and A is a scale factor related to grain size. The use of the Dean and Hallermeier/Birkemeier concepts provides a direct method for estimating nourishment quantities for various wave and sand source conditions. These concepts are generally accepted in the industry but are not widely used by designers, because overfill and renourishment factors are used to determine fill compatibility. Since profile shape change and winnowing occur on nourished beaches, both measures need to be considered in a design when the borrow sand is finer than the native beach sand. When an unconsolidated beach is nourished for the first time, sand will move offshore in sufficient quantities to flatten the offshore profile. Significantly less sand will move offshore in subse- quent nourishments, because the slope of the beach will have already been mod- erated by the first nourishment. The response of the native and natural beach to higher sea levels was first addressed quantitatively by Bruun (1962~. He suggested a balance of onshore erosion with offshore deposition in response to a change in sea level. Storm recession methods were proposed by Edelman (1972) using an approach similar to that of Bruun and applying these principles to storm surge. Edelman's method was used in a number of federal beach nourishment designs in the 1970s and 1980s (Strock and Associates, 1981, 19841. His method tended to overpredict storm recession,-because the technique assumed the profiles would reach full equilibrium with the peak storm surge without consideration of the duration of the storm. Swart (1974) proposed methods to evaluate erosion induced by storms based on evaluation of coastal erosion problems on the Danish North Sea. Kriebel (1982) developed a time-dependent dune recession model based on the equilib- rium profile and a uniform dissipation of wave energy per unit volume in the surf zone. This method was further developed and described by Kriebel and Dean (19851. In the Kriebel-Dean method, storm duration, waves, and storm surge were combined for the first time to analyze the profile response in storms. More recently, this model has been refined (EDUNE) by Kriebel (1990) to account for the existence of coastal structures and overtopping of the profile by wave runup. From 1988 through 1990, Larson (1988) and then Larson and Kraus (1989b)

APPENDIX D 193 developed the SBEACH (Storm-Induced Beach Change) model for predicting beach and dune erosion. This model allows for offshore bar formation during storms. It was recently refined (Wise and Kraus, 1993) to include the effects of seawalls, runup, and overwash quantities of sand that are pushed over the dune. The EDUNE and SBEACH models are the two numerical dune recession models in use today by U.S. beach designers. An analytical model for storm recession was first developed by Kriebel et al. (1991) and refined by Kriebel and Dean (1993~. The erosion rate of the nourished beach has been estimated by beach design- ers primarily by using historical erosion rates. Fill is added to the design quantity in sufficient volume to account for beach losses between nourishments. This additional quantity is called advanced fill. Most federal designs prior to 1983 estimated advanced-fill requirements based on the rate of erosion of the native beach and grain-size considerations only. The USACE issued a technical note on beach fill transitions (USACE, 1982a) that suggested the inclusion of "end losses" in advanced-fill quantities. Pelnard-Considere (1956) developed an analytical one-line (i.e., the shore- line) model to predict spreading losses of nourished sand to adjacent beaches. Bakker (1968) developed a two-line analytical model to predict alongshore and cross-shore changes. Perlin and Dean (1979) developed an N line analytical model that enabled prediction of the evolution of multiple contours along a project's beach. As noted in Appendix C, Price et al. (1973) and Komar (1973, 1977) demonstrated a range of computer-based numerical models for shore pro- cesses. Price et al. (1973' correlated computer-based models with the perfor- mance of sand in a groin field. These models were not commonly used for nourishment designs until the late 1970s and early 1980s. Hanson and Kraus (1989) developed a one-line (i.e., the shoreline) numerical model that is referred to as GENESIS (Generalized Shoreline Simulation Sys- tem). This model was applied by the Coastal Engineering Research Center (CERC) to the design of the Asbury Park to Sandy Hook, New Jersey, beach nourishment project in 1985. The GENESIS model was refined by CERC as a personal computer application and applied to a number of beach nourishment designs in the early l990s (see Manatee County General Design Memorandum, USACE, l 991 c). Dean (1983J refined the work of Pelnard-Considere to further develop an analytical model for the prediction of performance of beach nourishment. It was applied to a number of beach nourishment projects in the late 1980s and early l990s (Coastal Planning and Engineering, 1992a, b; USACE, 1989b) and has shown good correlation to monitored projects in Delray Beach, Florida (USAGE, l991c); see also Appendix C.

94 BEACH NOURISHMENT AND PROTECTION DESIGN METHODS Fill placed on a nourished beach will erode over time, diminishing the pro- tection afforded by the initial construction. Most nourishment projects are actu- ally designed as a series of sequential fill placements over time to account for the long-term erosion process. For design purposes, it is convenient to consider the fill placed on a beach as comprised of two components: the design cross-section, which achieves the project purpose (storm protection and recreational area), and an advanced-fill amount, which erodes between nourishment events (see Figure 4-7~. Federal design policy (USAGE, 1991b) requires that the design cross-section be optimized to return maximum net benefits (benefits less costs). The advanced- fill quantities are designed to achieve the lowest annual cost for the renourishment program. The construction volume contains both design and advanced-fill quantities. Construction templates reflect dune and berm elevations. However, the construc- tion template incorporates a significantly wider berm and a steeper slope than the design and advanced-fill profile. The difference between the construction, de- sign, and advanced-fill profile is necessary to accommodate the sand placement capability of the construction equipment that is expected to be available for the project. Within the first year or so after placement of beach fill, the construction profile will be reshaped by waves to an equilibrium profile, causing the berm to retreat to the design and advanced-fill profile (see Figure 4-7~. For design pur- poses, the construction profile is treated as an anomalous temporary feature. The Design Beach ~' It is standard practice to provide sufficient sand to nourish the entire profile, from the dune (where one exists) to the depth of significant sand movement, do . Estimates of fill are based on transferring the entire active profile seaward by the design amount (see Figure D-1~. If the borrow sand matches the native sand and there are no rock outcrops, seawalls, or groins, the design profile at each cross- section should be a replica of the existing profile but shifted to a seaward loca- tion. Enough sediment should be accounted for by the designer to nourish the entire profile (Bruun 1986; Hansen and Lillycrop, 19883. The total volume, VT, is independent of profile shape, since the shape of the reflourished profile will be parallel and similar to the existing natural profile. Using the limiting depth of profile change, dL' the nourishment quantity can be directly estimated by VT = (B + dL ~ L W (D-2) where B is the elevation of the berm as discussed in Appendix C, L is the length

APPENDIX D 4 3 2 1 ~ O o -1 UJ -2 -3 -4 195 Design Beach Do .. _ , Hi; ~ NGVD Depth of Closure 1 1 1 1 1 0 50 100 150 200 250 300 DISTANCE (m) FIGURE D-1 Design cross-section transferred seaward. of the nourishment project, and W is the desired amount of beach widening (Campbell et al., 1990~. If rock outcrops or other nonerodible surfaces such as seawalls, revetments, or groins exist on the nearshore native beach, the existing profile shape will not be directly representative of the nourished profile. If a beach that is armored (such as with seawalls) has experienced erosion over an extended period, the nearshore bathymetry can become deeper and the profile will be steeper than the equilibrium natural profile. This condition would be expected to result in the need for a larger amount of fill during the initial nourish- ment. In such cases, the use of an equilibrium profile defined by the grain size of the borrow material or an adjacent natural beach profile can be used to approxi- mate the nourished profile. Further, if seawalls, groins, or other structures or features have caused the profile to deviate significantly from the anticipated equilibrated profile after nourishment, then Equation (D-1) would be applied with appropriate modifications. Figure D-2 shows the monitored profiles of a nourishment project in Captiva Island, Florida. The project was constructed in the winter of 1988-1989 with 0.56-mm sand; the sand was coarser than the native beach sand of 0.38 mm. The project has been monitored twice a year since nourishment. The profile shown in Figure D-2 is a typical profile 5 years after the construction of a project. The

96 4 3 2 ~ O _ By O _ ~ -1 - LU -2 3 4 BEACH NOURISHMENT AND PROTECTION ~08/1 3/88 _, ,,f<: \& \\ - APR. 1993 OCT. 1993 NGVD ~ r I I I I I ~ ~, . . . -50 0 50 100 150 200 250 DISTANCE (m) FIGURE D-2 Captiva Island beach nourishment monitoring cross-section. nourished profile is similar to the native profile at a seaward location. Review of the profiles shows that they experienced little change beyond the 4-m depth contour. It is common practice, however, to utilize uniform slopes for the design cross-section and to use this cross-section for the entire beach (see Figure D-31. When this is done, it can lead to an underestimate of the fill if the design cross- section intercepts the bottom above the depth of closure. If rock, clay, or peat outcrops (or, in the special case of the Arctic, perma- frost) exist, the shape of the native beach profile will be affected. In those cases, the nourished profile will take a different form than the native beach, and nour- ishment quantities cannot be estimated directly by shifting existing profiles sea- ward. Rock outcrops, offshore hard clay, and glacial till tend to flatten the native beach offshore profile and will perch the nourishment sand, requiring less sand to widen the beach a specific amount. Where rock exists, the best way to estimate design quantities is to use the equilibrium profile based on the grain size of the borrow materials and allow the profile to intercept the offshore areas above the depth of closure of the profile. Volumes of design fill can then be estimated by direct comparison between the nourished equilibrium and the native profiles.  It is a customary objective for nourishment designs in the United States to establish a uniform beach width along a project's length. The existence of sea- walls can increase design beach requirements over estimates based on the sea- ward transfer of the profile. If a segment of the project shore has a seawall on or

APPENDIX D 4 2 1 o o IL 111 -c -4 197 Linearized Beach Slope - Approximation of Design NGVD Intercept Above Depth of a ; . . ~/ Closure Underestimates Design Fill - - - - - - - - 1 1 1 1 1 ~ 0 50 100 150 200 250 300 DISTANCE (m) FIGURE D-3 A linear design cross-section sometimes intercepts sandbars, providing an underestimate of design fill. near the water's edge, an amount of fill will be needed to bring the elevation of sand up to the proposed berm elevation in the area where seawalls exist. This can  significantly increase the fill requirements where seawalls are in the water. Once these "seawall volumes" are established, nourishment fill estimates can be based on transfer of the entire profile. This is important because gross volume estimates are made in the preliminary phase of a project's design. The project's sponsors base their support and budgets on these early estimates. In the final design, template comparisons will include extra volumes to fill seawall areas. If the preliminary design volume is significantly deficient because the seawall volume was missing, the designer may encounter pressure to compromise the design in order to avoid project cost overruns. Figure D-4 shows the design cross-section of a nourishment project planned for Captiva Island, Florida. The shaded portion of the profile is that amount of sand needed to bring the beach level up to the proposed berm level before the beach berm is widened. Sand is needed along the entire profile both subaerially and below the water. Once this amount of fill is accounted for, fill volumes can be estimated by shifting the profile seaward using

198 - 4 _ 2 - O O UJ -2 -4 -6 BEACH NOURISHMENT AND PROTECTION Seawall _~: --- 08/13/88 APR. 1993 OCT. 1993 NGVD Extra Volume Needed for Beach Areas Where Seawalls are in the Water l L -50 0 N"W 1 1 1 1 1 1 1 50 100 150 200 250 DISTANCE (m) FIGURE D-4 Captiva Island beach nourishment monitoring cross-section at R-98. Equation D-1. Because of the extra volume needed to build the berm in front of seawalls, the nourished shoreline will typically be shifted seaward in front of seawall areas as compared with nonseawall areas. This will cause alongshore gradients in littoral drift that need to be considered in advanced-fill designs. In USACE projects the target shoreline is designed to be fairly even. Any perturba- tion (such as a seaward-displaced shore to accommodate a seawall) will become an erosional hot spot. Surveyed profile variabilities are typically used to compute the quantities needed. The alternative to providing seawall volumes is to allow for narrower berms in front of seawall areas. The storm protective value of the seawall reduces the need for storm protection provided directly by the berm, enabling the use of a narrower width than would otherwise be necessary to achieve the same level of storm protection. The use of a narrower berm reduces or mitigates the littoral drift gradients associated with overly wide sections of nourished beaches in front of seawalls. The design beach is optimized by computing costs and benefits and determining the beach that would return the maximum net benefits (USAGE, l991b). Both storm damage reduction and recreational benefits are included in the analysis. Storm damage benefits are based on the reduction in storm damage over the life of the project with the design beach in place. Because of the existence of the design beach, the upland properties will suffer less damage during each storm

APPENDIX D 199 event. Damage estimates are based on inundation, wave attack, and erosion dam- ages (USAGE, 199 lb). Beach washout and profile response seaward of seawalls during a storm can be predicted using beach and dune recession models. Commonly used approaches include EDUNE by Kriebel (1986) and SBEACH (Larson and Kraus, 1990~. These models predict the evolution of the profile toward the equilibrium storm profile. Both models are driven by the deviation between the actual and equilib- rium wave energy dissipation per unit volume of water within the surf zone. The models assume that sand eroded from the upper beach deposits offshore, with no loss or gain of material to the profile. Storm surge estimates to be used in recession models and for calculating runup are based on methods described in Chapter 3 of the Shore Protection Manual and other engineering manuals published by the USACE (1984, 1986, 1989a). Many beach designers use published storm-surge frequencies developed by the Federal Emergency Management Agency (FEMA) and the National Oce- anic and Atmospheric Administration (NOAA). Storm hydrographs can be ob- tained from reports published by USACE, FEMA, and universities to generate storm recession probabilities that can be applied directly to damage functions and included in an economic model. Wave statistics can be obtained from wave gauge records, published summaries of observations, or wave hindcast estimates, such as the Wave Information Study (USAGE, 1990, 1993~. It has been recognized that storm surge frequencies are not necessarily the same as damage frequencies (Kriebel and Dean, 1985; USACE, 1986, 19884. Beach and dune recession, for example, is dependent on storm duration and wave heights, as well as on storm surge. To address this problem, the USACE (1988) developed a storm simulation model for a project in Seabright, New Jersey, which develops a family of storm events similar to the historical record. In this way a series of storms was developed and used in the storm recession model to establish a series of storm recession events that could be independently ranked. Similarly, wave runup and flooding can be ranked from the 500-year event to the 10-year event. A more representative damage frequency curve can therefore be used to compute storm damage and protection values. Natural and nourished beaches exhibit a variability in the level of storm recession measured along their length (USAGE, l991b). Some areas will show extensive washout, while others exhibit minor storm recession. Variability can be estimated by measuring poststorm beaches in the project area and establishing the levels of variability to be applied to the model. For example, if it is determined that beach recession varies by a factor of two, beach recession will vary from zero to twice the average that is represented by the computed value. As mentioned previously, the design beach is optimized by maximizing total net benefits, including storm protection and recreation. Recreational benefits are generated when a nourishment project rebuilds or maintains a public beach area. It is important for designers to recognize the basis for this economic benefit. If a

200 BEACH NOURISHMENT AND PROTECTION public beach erodes away, recreation on it is eliminated; therefore, a benefit is derived from building and maintaining a beach. More people will visit a nour- ished beach over the project's life, generating a net benefit to the nourishment project. Beach visits saved or increased by beach nourishment represent an eco- nomic benefit. Using standard economic principles, the annual costs and benefits of a project are compared to establish the design beach. The design beach is that added width of beach that returns maximum net benefits. Advanced-Fill Design Both the quantity and distribution of advanced fill the erodible portion of the profile before nourishment becomes necessary can be determined by ana- lyzing the historical erosion and shoreline changes of a beach and estimating how the project fill will affect coastal processes. Procedures used include the histori- cal shoreline change method (USAGE, l991b) or analytical (Campbell et al., 1990) or numerical methods (Hanson and Kraus, 1989~. The historical shoreline method assumes that the nourished beach will erode at the same rate as the prenourished beach. This method is commonly used by beach designers (based on survey results) but can yield a significant underestimate of nourishment re quirements, as discussed below. Most long-term erosion of a nourished beach is caused by increasing gradi- ents of littoral drift along the project's length. The two major littoral drift gradi- ents affecting the nourished beach are the preexisting littoral drift gradients that were responsible for the background or historical erosion of the prenourished beach and those gradients associated with the anomaly in the shoreline created by the project fill that cause end losses and spreading of the fill. All of these littoral drift gradients combine on the nourished beach to cause a progressive loss of fill from the beach nourishment project. Exclusive consideration of the background erosion rate neglects the end (i.e., spreading) losses, causing an underestimate of nourishment needs and thus an overestimate of project life. Losses from the project area due to spreading will cause accretion of sand on adjacent beaches. Although this may be beneficial to the adjacent beaches, the spreading losses from the project must be included in the advanced-fill design in order to achieve performance objectives for the project area. Delray Beach, Florida, is an example of a beach nourishment project where spreading losses represented the greatest component of the erosion rate on the nourished beach. The beach nourishment project was constructed in 1973 with 1.2 million m3 of sand from an offshore borrow source. Prior to the project, the beach was eroding at a rate of 15,000 m3/year. The beach has been monitored annually since 1973 with profiles from the dune to the 10-m depth contour. From 1973 through 1978, the beach eroded an average of 70,000 m3/year. The beach was renourished in 1978, 1984, and 1992. The erosion rate (the entire profile)

APPENDIX D 201 was again about 70,000 m3/year from 1978 through 1984. Between 1984 and 1992, losses moderated and averaged 35,000 m3/year. Over half of the sand lost from Delray Beach can be accounted for as accretion on adjacent beaches in Highland Beach and Gulfstream (Beachler, 19931. This example demonstrates the importance of estimating spreading losses in the design of beach nourishment projects. Along a project's length, gradients in littoral drift occur as a result of changes in the shoreline orientation or wave refraction and diffraction over discontinuous offshore contours (such as ebb shoals). This creates conditions of differential erosion and accretion along the project shore. The distribution of advanced-fill quantities ideally should be placed to anticipate these differences in expected erosion rates along the project. One such area mentioned earlier is the nourished beach in front of seawalls. A beach that is over-widened to provide a uniform berm in front of a seawall will erode faster as sand spreads to adjacent areas. Advanced-fill designs therefore need to recognize and accommodate these losses. Analytical methods have been developed by Pelnard-Considere (1956) and refined by Dean and Yoo (1992) to estimate net erosion losses from a project fill. These methods can be used to estimate gross advanced-fill quantities and are good tools to help designers develop judgment about the level of losses to expect from a project over time. Analytical models can be used by designers during the preliminary design phase to establish early estimates of gross fill quantities (see Appendix C). Numerical methods such as the GENESIS model (Hanson and Kraus, 1989) can estimate differential erosion patterns along a project's length to help design the distribution of advanced-fill placement. Calibrated numerical models predict both total erosion losses and differential erosion losses along a project. When numerical models are used for both purposes, however, analytical methods should be used in addition to the numerical models as a check on total erosion of the project fill. Sand Compatibility The grain-size distribution of the borrow material (nourishment sand) will affect how a beach erodes and how the nourished beach responds to storms. Nourished sand that is finer than the native material will form flatter slopes on the beach and underwater and provide a narrower dry subaerial beach. The most widely used methods are to compute the adjusted factor overfill, RAP and renourishment factors, R) (USAGE, 19841. The overfill method, RAP estimates how much of the borrow sand matches the native beach sand distribution. This method assumes that the nourished beach sand will undergo sorting as a result of coastal processes and will in time ap- proach the native grain-size distribution; the portion of the borrow sand not matching the native sand will be lost offshore. This method provides a multiplier

202 BEACH NOURISHMENT AND PROTECTION for the amount of borrow material needed to produce the required comparable amount of native material (USAGE, 1984~. The renourishment factor, RI, addresses the higher alongshore transportabil- ity of the finer grain sizes in the borrow sands. RI provides estimates of advanced- fill or renourishment needs. There is some question about the continued use of grain-size comparison RA and R) as measures of beach performance (Bruun, 1990; Campbell et al., 1990; Pilkey and Clayton, 1987, 1988; Dixon and Pilkey, 1989, 1991; Leonard, 1988; Leonard et al., 1989, 1990a, b). A more appropriate design approach would be comparisons of native and borrow sands based on the evolving concepts of the equilibrium profile (Dean, 1983,1991), alongshore transport dependency by grain size (Dean and Grant, 1989; USACE, 1984), and the storm recession perfor- mance of a beach with various grain sizes (Larson and Kraus, 1989a). This design approach has been suggested by Campbell et al. (1990~. Because finer beaches take flatter slopes than coarser beaches, they would require more fill to provide the same amount of beach widening. Estimates of these quantities can be made using the mean grain size of the borrow and native materials and the equilibrium profile concepts shown in the section on "Predic- tion" in Appendix C. If the material used to nourish a beach is finer than the native material, extra fill will be needed to flatten the slopes of the nourished beach. This extra fill is required only for the first nourishment; renourishment quantities would require no additional materials because slopes would already be adjusted by the first nourishment. Very fine portions of the fill such as silt and clay will be lost offshore during nourishments and renourishments. Most of the loss of fine material occurs during construction. It is therefore not customary to count these losses in the pay quantities. For the same wave climate, the rate of alongshore transport is dependent on the grain size of the sediments (Walton, 1985; Dean, 1987; Kamphuis, 1990, 1991; Kamphuis et al., 1986; del Valle et al., 1993~. Although field measure- ments of this dependency in the sand-size range of sediments are limited and of questionable validity (Komar, 1988), estimates have been made by Dean (1989) and USACE (1984) of the variation of alongshore transport with grain size. Further evidence and quantification of the dependence of transport on sand grain size have been shown by the USACE (1985~. The transport rate variance with grain size can be applied through analytical and numerical models to predict the erosion rates of dissimilar borrow sands. Long-term erosion and, therefore, renourish-ment quantities for finer sands would be greater than for coarser sands and can be estimated by this procedure. Although it is widely recognized that grain size affects transport rates, there are few empirical data on these effects. Therefore, transport rates must be estimated, and the accuracy of these estimates is uncertain. Research is needed to better define grain size and transport rate relationships. For the same wave climate, finer sands are more prone than coarser sands are

APPENDIX D 203 to erosion during storms with a storm surge of more than a 6-hour duration. This can be considered in the analysis of a design beach for storm protection. Gener- ally with a significant storm surge and storm duration, more fine sand will be required to protect upland property against undermining than would be required if coarser sand were used. Coastal models such as SBEACH and EDUNE take . . . grain size Into account. Finer sands are not always more prone to erosion during storms than coarser sands. The selection of a fine sand lessens the slope of the beach, which causes waves to break farther offshore, especially when there is a limited storm surge. If this occurs, wave energy is dissipated over a wider surf zone. Beaches consisting of coarser sand have steeper slopes and narrower surf zones. As a result, wave energy is more concentrated and therefore more directly impacts the shore. When affected by the same wave conditions without storm surge, the profiles of coarse- sand beaches undergo larger and more rapid changes during storms of limited duration and surge than profiles consisting of fine-sand beaches and show greater responses to individual storms (Shih and Komar, 19949. Therefore, the selection of coarser sand for a nourishment project may increase the dynamic behavior of beach profiles, leading to greater erosion during storms of limited duration with small storm surges. By considering the above described performance characteristics of sand, assessment of alternative borrow areas can be made. This analysis can comple- ment or substitute for the overfill and renourishment factor approaches previ- ously mentioned. Before performance-based analysis can replace overfill meth- ods, however, further research is needed to refine the dependency of sand transport . . on grain size. Design and Construction Profiles The design profile is the cross-section that the equilibrated beach is expected to take. On sandy beaches the best estimate of this profile is obtained by the seaward transfer of the existing beach by the amount of beach widening that is required (USAGE, 1992b). Estimates should be modified if the borrow material is of a different grain size than the native material. For finer sands, these adjust- ments in volume should be based on the amount of fill needed to adjust the offshore slopes from the shoreline to the depth of closure. Many designers specify linear design slopes as an approximation to the native beach and use this to estimate design volumes. This is a convenient and standard method to compute design volumes: superimposing a template over existing profiles and computing the resulting volumetric difference. However, if the design template intercepts a nearshore sand bar on the design beach profile, the designer will underestimate the design fill needs (see Figure Dub. For this reason, this method should be used with caution and judgment. It is suggested

204 BEACHNOURISHMENT AND PROTECTION c In > (D ~ 1. _1 . ~ ~- ~ \x \ )/ ~ \ \ At_ Construction Template (Temporary) Fill Redistributes by _ / Wave Action After \ ~ Construction _ swl FIGURE D-5 The construction template. that designers modify these procedures to better approximate equilibrated pro- files using the methods described above. The construction profile is the cross-section that the contractor is required to achieve. The constructed beach contains both the design fill and the advanced-fill quantities and is often steeper than the design cross-section because of construc- tion limitations. The construction cross-section is usually significantly wider than the design profile because of the steeper slopes and because it contains the advanced fill (Figure D-5. Wave action causes an adjustment of the construction cross-section to a flatter equilibrium slope; this usually occurs within the first few months to a year. Since the adjusted equilibrium profile contains the design and advanced fill, it is wider than the design profile during the renourishment interval. At the time of renourishment, the design and equilibrium profile would (theoretically) be equal. PLACEMENT OF NOURISHED SEDIMENT ON THE BEACH PROFILE Various design schemes have been used for the placement of nourished sediment on a beach. The approaches in common use are illustrated schemati- cally in Figure D-6 and include (1) placing all of the sand as a dune behind the active beach, (2) using the nourished sand to build a wider and higher berm above the mean water level, (3) distributing the added sand over the entire beach profile, or (4) placing the sand offshore to form an artificial bar. The selected design depends in part on the location of the source material and the method of delivery to the beach. If the borrow area is on land and the sand is transported by trucks to

APPENDIX D A. Dune Nourishment B. Nourishment of Subaerial Beach C. Profile Nourishment swl swl - D. Bar Nourishment _~ FIGURE D-6 Nourishment profiles. 205 swl swl _, the beach, placement on the berm or in a dune is generally most economical. If the material comes from offshore dredging, it is usually more practical to place the sand on the beach and near the shore or to build an artificial bar. After construction, sand is redistributed in the cross-shore direction to form a more natural profile, governed by the sediment size of the fill and the prevailing wave conditions. This is illustrated schematically in Figure D-7 for nourishment placed on a beach as a "construction profile" to form a wide elevated berm

206 BEACH NOURISHMENT AND PROTECTION 6 4 2 _ <-~-W,~ \` E ~x Z O _ _ ·k ~. _ O ~ \` ~CONSTRUCTION PROFILE ~ -2 ~"~/ 111 ~ '> DESIGN (ADJUSTED) PROFILE 4 _ hi:,": -6 r -8 1 1 1 1 1 -50 0 .. SW' PRE-FI LL PROFI LE 50 100 150 200 250 DISTANCE (m) 300 350 400 FIGURE D-7 Sand redistribution in the cross-shore direction to form a more natural profile. (Houston, 1991a). This placement artificially steepens the beach and results in the offshore movement of sand as it is reworked by the waves and redistributed over the profile. The "equilibrium profile" of Figure D-7 is the profile predicted by the analysis as the equilibrium profile that will eventually be achieved by the nourished sand after its initial reworking. This adjustment, as noted earlier, usu- ally requires a few months to several years. For this reshaping, the first year after placement may not be a sufficient interval if incident forces are unusually mild during the initial winter season. Figure D-8 provides an example of such profile changes derived from the monitoring program at Ocean City, Maryland (Hous- ton, 1991a). The nourishment fill was in the form of a uniform sand slope over the prefill profile, confined to the berm and inner surf zone. After four months, the resulting profile (labeled "01/17/89" in Figure D-8B) shows the expected readjustment into a more natural profile, with sand having eroded from the nour- ishment wedge to form an alongshore trough and the eroded sand having moved offshore to form a bar. The profile of 04/20/89 in Figure D-8C shows the effect of the first major storm that enhanced the formation of the alongshore trough and bar, with significant erosion of the nourished sand placed on the subaerial part of the beach. That erosion of the berm did not represent a permanent loss of sand from the beach, however, as it was deposited on the offshore bar and therefore was still landward of the closure depth of profile changes. The profiles of Figure D-8C show the subsequent onshore return of much of that sand during the lower- energy conditions following the storm, with the width of the berm expanding.

APPENDIX D 3 2 ~ ·'` LL J -2 111 3 4 r A. Initial Readjustment Profile line 14 - 04/16/89 Pre-fill _ 04/22/89 Post-fill . . 01/17/89 4 months B. Storm Impact 2 ?` Profile line 14 E . ~- 01/17/89 Pre-Storms ~ 1 - .. ~ ·~. .` 04/20/89 Post-Storms -1 _ a , LL W ~ -2 r ~ -3 ~ 4 ~1 3 2 - z o 11J -' 1 o -1 3 4 r _ Ore _ _ _ C. Recovery Phrase W . ~% _ Profile Line 14 04/20/89. Post-Storms 04/20/89 9 months 01/20/89 12 months ~-  ~-=~ - ·-.W 0 100 200 300 DISTANCE (m) FIGURE D-8 Ocean City, Maryland, project profiles. 207

208 BEACH NOURISHMENT AND PROTECTION Larson and Kraus (1991) have similarly analyzed the readjustment of nour- ished profiles as they are first eroded by normal waves and subsequently attacked by a hurricane or northeaster. They utilized the numerical model SBEACH to evaluate the profile changes in response to "synthetic" storms and obtained re- sults very similar to those seen in Figure D-8 for Ocean City. With profile adjustments such as those illustrated in Figure D-8, the general public may perceive the loss of nourished sand from the berm to the offshore as a sign of failure of the project. There is a need for public education at the onset of a project so that the public understands that some initial offshore sediment move- ment and erosion of the berm are expected and recognizes that, so long as the sand remains in the littoral zone within the envelope of beach profile changes, the sand has not actually been "lost." Although the profile adjustment will in most cases result in shoreline recession, the material will still be present in the active beach profile; much of it will be in the offshore bar and on the berm. Further, the presence of sand in the offshore bar acts to break stories waves and to dissipate their energy before they reach the shoreline; accordingly, the nourished sand within the bar is still meeting the objective of protecting the coast from property erosion. When sand placed on a beach is finer than the native beach sand, the profile adjustments will be greater, taking more sand from the subaerial beach to flatten the offshore profile. If the designer has properly accounted for the difference in grain size, the equilibrated beach will be of a width and height to provide the desired level of storm protection. If the effects of grain size have not been prop- erly considered, the adjusted profile may be narrower than desired. Hansen and Byrnes (1991) have investigated the optimum nourishment cross- section design for protection of the backshore against storm impacts. The beach profile response was modeled by using SBEACH, and the analysis was based on the nourishment project undertaken at Ocean City, Maryland, which involved the initial placement of about 2 million m3 of sand on the beach in June 1988. Six months after the project was completed, a northeaster hit the area, resulting in erosion of the beach with significant profile changes. Approximately one-third of the fill material was transported from the subaerial beach and deposited offshore between the 3- and 5.5-m water depths, but the total quantity of sand was con- served landward of the profile closure depth. Hansen and Byrnes (1991) used this measured change to calibrate SBEACH and then used the calibrated model to examine the responses of different beach fill designs (Figure D-6) that would have occurred under that northeast storm, including both measured wave heights and water levels in the model calculations. According to their analyses, all de- signs withstood the impact of one northeaster or hurricane. In simulations of back-to-back northeasters, the design involving the placement of all nourishment sand into a dune (Figure D-6A) provided the maximum protection of backshore properties, with some dune remaining even after two major storms. In the case of placing most of the nourished sand on the berm, SBEACH predicted that most of

APPENDIX D 209 the berm sand would have moved to the offshore bar. Therefore, excluding the desire to immediately have a wide berm for recreational purposes, the objective of providing backshore protection is best met by a profile design that places most of the nourished sand in dunes. The use of large dunes (i.e., man-made dikes) as a coastal protection measure has long been recognized in the Netherlands (Watson and Finkl, 1990; Verhagen, 1990; Louisse and van der Meulen, 19911. The coastal dunes there are, for the most, part man-made and are designed to withstand the 1-in-10,000-years condi- tion of wave intensity and storm surge. This extreme level of protection is justi- fied because entire cities lie behind the coastal defenses, whose failure would have catastrophic consequences. However, such an extreme storm condition or level of protection may not be definable. Maintenance of these dunes in part involves nourishment, with some sand also placed on the fronting beach. Bruun (1988, 1990) has been the primary proponent of nourishing the entire beach profile (Figure D-6C), which he terms "profile nourishment." The main advantage of this approach is that the sand is placed in approximately the same configuration as the existing profile, so that initial readjustments are, for the most part, avoided in particular the rapid erosion of a nourished berm. This would avoid some problems with adverse perceptions by the general public but, accord- ing to the analyses of Hansen and Byrnes (1991), would provide less protection from flooding and erosion compared with placement of the entire volume of nourishment sand in the dune and berm (Larson and Kraus, 1994; Williams and Meisburger, 19871. Beach nourishment has also involved the placement of dredged sand in the offshore (Figure D-6D; McLellan, 1990; McLellan and Kraus, 1991~. Dredged material is deposited in shallow water, typically using split-hull barges, either as a mound or in the form of a long linear ridge that simulates a naturally occurring alongshore sand bar (the term "offshore berm" is generally used for the con- structed bar but will not be used here because of potential confusion with the subaerial berm of the beach profile). It is expected that sand deposited in the offshore mound or bar will progressively move onto the beach, but even before that stage there may be benefits; the created bar could cause storm waves to break farther offshore, reducing the energy locally on the beach shoreward of the bar. This aspect of wave reduction has been shown in numerical models that calculate the theoretical wave attenuation owing to the presence of an offshore mound (Allison and Pollock, 1993) and also by field measurements of waves seaward and landward of a mound that is constructed from dredged sediments offshore from the entrance to Mobile Bay, Alabama (Burke and Williams, 1992~. Initially, there were disappointments in using offshore disposal to nourish adjacent beaches. For example, in 1935 the USACE built a sand bar at 6- to 7-m water depths off the updrift end of the eroding beach south of the breakwater at Santa Barbara, California. It was anticipated that this bar would supply sand to the eroding beaches. However, after 21 months of monitoring, there was no

210 BEACH NOURISHMENT AND PROTECTION movement of the bar and no alleviation of the shore erosion (Hands and Allison, 19911. After several such disappointments, successes were finally reported at Durban, South Africa (Zwamborn et al., 1970), at Copacabana Beach in Brazil (Vera-Cruz, 1972), and in Denmark (Mikkelsin,1977~. These successes rekindled interest in beach nourishment by offshore disposal, and in recent years this ap- proach has been used at a number of sites. The question remains as to why in some instances sand from the offshore nourishment mound or bar moves onshore to the beach so that the project is successful, while in other instances the dumped sediment remains as a stable deposit and does not move shoreward and onto the beach. Hands and Allison (1991) have reviewed a number of projects in an attempt to answer this question. They compared the disposal depth with the closure depth of beach profile changes as predicted in the analyses of Hallermeier (1981b) and found that, if the disposal depth is less than the closure depth, the disposal sediment would be active and move quickly onto the subaerial beach. This activity of the nourishment mound or bar placed at a depth that is shallower than the closure depth is not surprising because this placement in effect immediately introduces the sand into the near- shore zone of active profile changes where the nourished material can be readily incorporated into the overall beach profile. More uncertain, Hands and Allison (1991) found that if the disposal sand is placed at water depths greater than Hallermeier's closure depth, in half the cases the material was still active and moved onto the beach, whereas in the remaining cases the disposal sediment was stable and did not nourish the shoreward beaches. They also compared "stable" versus "active" disposal mounds and bars with the local wave climate and met with reasonable success in characterizing the sediment movement on the basis of the annual distribution of near-bottom wave orbital velocities calculated from measured wave parameters. As expected, if the orbital velocities were suffi- ciently high due to combinations of large waves and shallow water depths, the disposal sands remained "active" and tended to move onshore. "Stable" mounds like the one placed offshore of Santa Barbara during the 1930s were explainable in terms of the low-wave orbital velocities experienced over the mound. It can be expected that in the near future we will have a much better under- standing of the movement of offshore disposal sediments and that there will be established criteria to predict their onshore movement, so that the sediment suc- cessfully nourishes adjacent beaches. Much of this understanding will be derived from projects where the disposal mounds or bars are carefully monitored. Recent examples of such monitoring programs are provided by Andrassy (1991) and Healy et al. (1991), respectively, for beaches near San Diego, California, and off Tauranga Harbor, New Zealand. Healy et al. (1991) found that dispersion of the mound was rapid in the first 2 years, with some sand moving onshore to nourish the beaches, but that it progressively slowed and became stable after 7 years as the depth over the mound increased and a lag of coarse-grained material re- stricted further sediment movement.

APPENDIX D The Netherlands Method 211 Verhagen (1990) has described the beach nourishment design method em- ployed in the Netherlands, which, rather than relying on numerical models, places substantial reliance on historical data and makes few design assumptions. The recommended procedure is described in five phases: 1. Perform coastal measurements (for at least 10 years). Calculate the "loss of sand" in cubic meters/year per coastal section. Add 40 percent loss. Multiply this quantity with a convenient lifetime (e.g., 5 years). Put this quantity somewhere on the beach between the low-water- minus-1-m line and the dune foot. Verhagen addresses difficulties with this method, including approaches to use if detailed monitoring results are not available and the implicit assumption is that the beach will erode at the same rate as before nourishment. The explanation for the additional 40 percent volume is a recognition of end losses and the loss of finer particles during placement. According to Verhagen, the design basis for subsequent renourishments ought to be derived from the monitoring results of the earlier nourishments. Detailed placement on the profile is not a major concern because the waves will soon reshape the nourishment material. However, Verhagen indicates that the sand ought to be placed where placement is the least costly, as long as the site is within the nearshore zone of active wave breaking. In comparison with the U.S. methods described earlier, the Netherlands method is similar in accounting for background erosion. The major difference is that in the U.S. method the "spreading out" or "end" losses and other uncertain- ties are accounted for by a calculation procedure rather than the empirical factor of 40 percent that is used in the Netherlands method. The German Method Dette et al. (1994) have described a method employed in Germany that represents the volumetric losses over time from a beach nourishment project using the assumption that the volume decays exponentially with time. Presum- ably, the decay constant must be based on experience or, after the first and subsequent nourishments, the monitoring results from the project. This represen- tation, although approximate, allows analytical investigation of many design char- acteristics of interest. For example, it is possible to determine the total volumes required to maintain a beach at a minimum volume for various renourishment intervals. Also, it is shown that the minimum cumulative volume required to maintain the beach at a minimum width is accomplished by frequent additions of small volumes. However, the optimal nourishment frequencies must also con

212 BEACH NOURISHMENT AND PROTECTION sider the costs of mobilization and the fact that material lost through spreading flows to and benefits areas adjacent to the project. EVALUATION OF THE STATE OF THE ART OF DESIGN PRACTICE The design of beach nourishment projects in the United States has evolved as knowledge of physical beach processes has increased. By necessity, designers use those tools that are available and that will enable them to bring a project to construction. Because of limited survey monitoring, the validity of design as- sumptions and procedures cannot always be verified before the design of a renourishment project. The variability of storm conditions further compounds the process of design and verification. As a result of the above conditions, beach nourishment designers do not always consistently employ the latest design tools. This section identifies areas where improvements can be made to the design process to provide a more consis- tent and accurate beach nourishment design process. Areas where improvements are needed and can be made include: · design volume, · design of advanced fill, and · analysis of sand compatibility. The design volume needs to be (consistently) based on shifting each natural beach profile seaward by the design width in lieu of a single straight-line design template. This would avoid underestimates of fill where the design template intercepts sand bars and would take into account the natural variabilities of pro- file shape along the project. Where seawalls, groins, rock outcrops, or other structures or natural features exist, the existing profiles can be steeper than adja- cent natural beaches. In those cases, the design profile needs to be similar to the closest natural beach. An important design consideration is that profile steepen- ing of the native beach can be very significant and may necessitate more than double the fill density requirements of adjacent natural beaches. The design of advanced fill needs to accommodate the full range of condi- tions that will affect project performance. It is common for designers to specify a uniform advanced-fill amount for a project even though preproject erosion rates may have shown significant sporadic spatial variability. Advanced-fill quantities need to be proportioned along the project to anticipate expected erosion of each project segment. This is best accomplished by varying advanced-fill quantities consistent with preproject erosion rates and using the predictive tools that are available. These tools include use of analytical and numerical models and not just average background erosion rates. Although analytic and numerical shoreline models have been available since the early 1980s, their use has been limited.

APPENDIX D 213 Even when applied during project design, the results in some cases were not used to adjust advanced-fill quantities or distributions of that sand along projects. In most of the designs reviewed for this report, advanced-fill quantities were based primarily on average historical erosion rates distributed evenly along a project's length. An analytical model can be used during the preliminary design to estab- lish gross fill quantities. A numerical model can be used in the final design of a beach to establish the proper distribution of advanced fill. A performance-based procedure needs to be used in addition to RA and R~ to analyze sand compatibility, providing, as a minimum, a second estimate of fill compatibility. This is necessary to reduce the margin of uncertainty. The perfor- mance-based analysis would include consideration of the equilibrium profile, the alongshore losses, and the storm performance of the borrow sands, thus establish- ing a basis for evaluating the economic acceptability of the material. Further field and laboratory tests are needed to define the dependence of littoral drift rates on . . grain size. DESIGN FOR SEA-LEVEL RISE Since background erosion rates are used to design beach nourishment projects, these designs include the effects of relative sea-level rise over the period of the shoreline change data (see NRC, 1987~. If sea level rises at the same rate over the next 50 years, the nourishment design will include the effects of sea- level rise, as this effect is "built in" to the background erosion rates. If sea-level rise accelerates, additional sand will be needed in later renourishments. If the project is monitored effectively and the results are analyzed and applied, the effects of all physical factors on performance can be assessed and incorporated into renourishment designs. At each renourishment, an economic reanalysis is undertaken to determine if the project is still cost effective. This analysis is based on the actual performance of the project, which includes the effects of sea-level rise. If sea-level rise accel- erates, some projects may not be economically feasible in the future. However, because of the "noise" in the data on sea-level change, it may be several decades, at the earliest, before the role of any increases in sea-level rise can be determined. SAND BYPASS SYSTEMS In some regions the need for beach nourishment has resulted from sand being trapped by a harbor constructed (breakwaters) in the nearshore or by jetties built to fix the location of an entrance through a beach into an inland harbor. Where there is a net alongshore transport of sand, jetties and harbor construction can cause trapping of sand updrift of structures, within the entrance or harbor, and in an ebb-tidal shoal. It can also cause erosion of the downdrift beach. Sand must be dredged from the entrance channel and harbor, or from a sand trap constructed

214 BEA CH NO URISHMENT AND PROTECTION contiguous to and updrift of them, to maintain required navigation depths. In many cases, it is desirable that sand not accumulate updrift. It may be appropriate to bypass the sand around the barrier to nourish downdrift beaches. Similarly, sand that accumulates in navigation channels as a result of harbor protective works could also be placed on downdrift beaches to help restore the sand budget of the littoral system (Richardson, 19913. The amount of sand to be bypassed is established by the natural coastal processes in the region. The quantity needed for downdrift beach nourishment may be greater than the amount trapped in the entrance and harbor, and bypassing only this amount may not be sufficient to adequately maintain the downdrift beaches. The system designed to bypass the sand depends upon: · the quantity required to be bypassed, wave climate, and tidal characteris- tics; · the size and layout of the entrance and the harbor; · how often maintenance dredging is required; · how often nourishment is needed; and . the times of year that bypassing will be permitted (owing to environmen- tal and multiple-use requirements). The system that is optimum for maintenance dredging may not be optimum for beach nourishment (and vice versa), but the system chosen must be adequate for both functions. Owing to the complex relationships among wave dimensions and directional characteristics, water levels, and the transport and deposition of sand, a system that is optimum for normal use may be overwhelmed during some storms. The system used may have to be modified based on experience. Several different systems have been designed and used that may be appropri ate at a specific site: . mobile dredges in the harbor/entrance (Santa Cruz, California); · movable dredge in the lee of a detached breakwater forming the updrift sand trap (Channel Islands/Port Hueneme, California); · floating dredge within an entrance using a weir jetty on the updrift side (Hillsboro Inlet, Florida; Boca Raton Inlet, Florida; Masonboro Inlet, North Carolina; Perdido Pass, Alabama); fixed pump with dredge mounted on a movable boom (Lake Worth En- trance, Florida; South Lake Worth Inlet, Florida); · a series of fixed jet-pump/crater units mounted on a pier normal to the beach on the updrift side (Nerang River Entrance, Queensland, Austra lia); and jet pumps (eductor) mounted on a movable crane, with main water supply and booster pumps in a fixed building (Indian River Inlet, Delaware). .

lllllllllllsloxllllllllb-lllllllllllllllllllll 1"III~III~ I~=~I~I IIIBI 273 These and other instaNadons and 1beir operadonaI perchance He described in 1be OSACE's engineering and design manual !~ -~f~ ~~ 3~/~- ho~ (1991~\ Rich provides guidance far 1be design and evaluation of sand bypassing systems A coastal processes Judy far ~ project is very important (USAGE, 1991b). Also essential He sufficient refile data (see, fir example, Hereon and Ham 1966~. The in~adon son in Box ~-1 is based on quantitative data needed to plan ~ project. After 1be Rove in~adon teas been obtained or estimated, a system can be designed. Some details on layouts pumps, and 01ber mechanical components He avad~le in 1be USACE design manual ~EASLRI~G SUCCESS ~ucb of the debate over 1be perchance of bdacb noudshmen1 projects gems Tom 1be ~ 1ba1 project He omen criticized on 1be bash of publicly hated

216 BEACH NOURISHMENT AND PROTECTION positions and expectations that may not coincide with those of the design engi- neers. Nevertheless, opponents of beach nourishment projects have identified issues that need to be addressed during design, including the amount of dry beach added and the expected life of a project. Resolving these issues during design would further minimize uncertainties in prediction and would provide a more complete basis for assessing project performance. Success needs to be measured through comparisons of performance against design parameters, as determined through adequate monitoring with design pre- dictions. These include shoreline and berm positions, total volume, and the re- sponse of the beach to a storm. The first measure of success should be the longevity of the fill volumes- that is, the evolution of the fill from the construction volumes (design and ad 3.8 3.6 3.2 3.0 2.8 1 .e 1.6 1.4 3.4 ~ 2.6 _ 2 _ o, _ o 1.2 _ i, _ 1.0 -  _ - D :~ 0 0 co I Z - - FIGURE D-9 Nourishment fill performance at Delray Beach, Florida. ~ | ~ _ _ · ~ m ADZ ~ D |I a" · ~ _ ~ it ,, , , , ~ . , , , , . , , . \{ , , , ° ' ° ~ ~ ~ ~ ~ ~ ~ ~ al ~- ~- ~3 ~-$ ~9 '5

APPENDIX D INTERCOASTAL WATERWAY ~1.' - 1 MU ~ ~ 217 E ._ s In CO 1 a, NOTE: Seaward Scale is Exaggerated 10 x 11 , ~_ ~- / - I \ / Advance Fill ~ \v z co ' a, FIGURE D-10 Schematic of Delray Beach mean high water versus design. --- Design Fill MHW December 1992 MHW December 1993 MHW vanced-fill) to the design volume over the renourishment interval. Figure D-9 shows the volumetric change of the Delray Beach project with time, which can be used to analyze the erosion rate for the beach and predict the time for periodic nourishment. For example, Figure D-10 from Delray Beach, Florida, and Figure Dell from Captiva Island, Florida, show the mean high-water and berm crest locations versus the design beach standards. Figure D-10 shows that the beach exceeded the design standard mean-high water location as of 1993. Figure D-11 shows that the design berm crest has eroded, indicating the need for renourishment. HYBRID PROJECTS Hybrid projects are combinations of beach nourishment and structures, such as detached breakwaters, groins, jetties, revetments, seawalls, and submerged sills. There is a considerable body of knowledge on the structural design of the components and some information on their functional design. Procedures exist for the functional design of detached breakwaters and fill, and for groins and fill, but not for the other types of hybrid projects. Some examples of projects are given here to illustrate what can be done. Also given is information on their functional performance (nontraditional shore protection devices are discussed in Chapter 41. Studying these examples and others should help planners and designers decide whether to use a hybrid project at a specific site, rather than just beach nourishment. One type of hybrid project, a perched beach, which consists of a fill and an underwater sill to hold most of the

218 ~20 llJ cn 40 50 6n 70- FIGURE D- 1 1 October 1993. BEACHNOURISHMENT AND PROTECTION lo... ,~.t ,~eO^~~ ~§ ~ ,~ Far ~ 1986 Renounshment Project Fill Locations n -aye ~ ~ Advance Fill Design Fill Berm - Design Fill and Advance Fill Berm · October 1993 Berm Captiva Island project showing designed versus actual berm locations in sand from moving offshore seaward of the sill, has been used only twice in the United States, although its possible use has been discussed a number of times. Such projects have been used in a few other countries, and examples are given in this appendix. Detached Breakwaters Although hundreds of detached breakwaters, usually shore parallel, have been constructed worldwide to hold sand on beaches using the tombolo effect (Silvester and Hsu, 1993; Wiegel, 1988), only 21 major projects (235 segments) have been built in the United States (Chasten et al., 1994~. Many of the projects have functioned well (Hanson and Kraus, 1991~. However, breakwaters some- times cause downdrift erosion if there is a net alongshore littoral transport in the region. In some circumstances they may fill too much, causing other problems (Wiegel, 19871. There are a large number of papers on the theory and design  (both functional and structural) of detached breakwaters and their effects on beaches (see, for example Dally and Pope, 1986; Rosati, 1990~. The detached breakwater and beach fill at Redington Shores on the Gulf of Mexico coast of Florida was constructed in late 1985 and early 1986 (Terry and Howard, 19861. The northern 80 m of the rubblemound structure is parallel to the

APPENDIX D 219 Pinellas County Park seawall and about 100 m seaward of it, with a 30-m-long 45 degree (seaward) dogleg at the southern end. The breakwater was constructed in 3 m of water, and the crest elevation was originally at +0.5 m above mean low water. About 23,000 m3 of sand was placed along 300 m of shore in front of the seawall. A tombola formed in the lee of the breakwater, extending out to 35 m from the seawall by April 1, 1986 (Terry and Howard, 1986~. By October 1987 it had nearly reached the breakwater. Between April 1986 and February 1988, 44,000 m3 of sand had accumulated in the survey area, including the 23,000 m3 of initial fill (USAGE, 1992a). In August 1988,38 armor stones were removed from the breakwater to lower the crest elevation to 0.1 m above mean low water so that more wave energy would overtop it, and 290,000 m3 of fill was placed for the authorized Pinellas County project, a portion of which was placed at the site (USAGE, 1992a). Monitoring data on the project are available in a paper by Davis (1991~. When the committee members visited the project on February 8, 1993, the sand beach was out to the edge of the breakwater at low tide. For the safety of beach and water users, a series of poles and a line with floats had been installed just landward of the structure, together with a warning sign. Lakeview Park, Ohio, is located on Lake Erie about 40 km west of Cleve- land. The coast in this region consists of glacial till bluffs about 6 m high, which were eroding (recession rates of 0.6 to 1 m/year) and would continue to do so unless protected artificially (Pope and Rowan, 1983~. The project, completed in October 1977, has three detached rubblemound breakwaters, each 75 m long, roughly parallel to shore, and separated by 50-m gaps (Hanson and Kraus, 1991~. They are located in water depths ranging from 3 to 4 m, depending on the lake level, with the west end of the west breakwater 135 m offshore and the east end of the east breakwater 150 m offshore. A groin was constructed at each end of the fill, about a half a kilometer apart. About 85,000 m3 of sand (0.5 mm median diameter) was placed to form an artificial beach about 60 m wide. The berm elevation was +2 m low water datum (LWD), and the sand was placed with a 1 on 5 slope into the water (Walker et al., 1980~. Backpassing of sand is performed at yearly intervals by the city of Lorain, Ohio, using either dump trucks or pumps (Bender, 1992~. About 3,000 m3 is backpassed each time from the east (downdrift end) to the west (updrift end). Groins Groins can be beneficial, they can serve no useful purpose, or they can be harmful, depending on local conditions. As is well known to coastal engineers and scientists, groins do not create sand; they only affect its disposition. They serve no useful purpose unless there is alongshore transport of sand at the site. When used, it must be understood by all concerned that a long-term maintenance program is required. There is extensive technical literature on groins, some of which includes information on their use with sand fill. An annotated bibliography

220 BEACHNOURISHMENT AND PROTECTION has been prepared by Balsillie and B~no (1972). Some details on design proce- dures, including sand fill, are given in the Shore Protection Manual (USAGE, 1984) and by Kraus et al. (19941. There are instances where groins have been installed as part of a project plan but without the sand fill being implemented. A well-known example of an incom- plete project is at Westhampton Beach, on the Atlantic shore of Long Island, New York (Kraus et al., 19941. Fifteen quarry-stone groins were built in two incre- ments, eleven from 1965 to 1966 and four from 1969 to 1970 (interestingly, they have required no maintenances. They are about 400 m apart and 146-m long along a 5,600-m section of shore. The original plan included an extension west- ward to Monches Inlet with six more groins, but a 4,000-m gap exists between the last groin and the inlet owing to the objection of the Cupsoque County park management to placing groins on the park in this section of the beach (O'Brien, 19881. Beach nourishment and dune construction were part of the plan, but the sand fill in the 10 compartments between the first 11 groins was not made owing to local economic problems. Dune and beach fill was placed in the four westerly compartments when the additional groins were built (Nersesian et al., 1992~. The first 10 compartments have filled naturally (substantially, including the forma- tion of dunes); this has deprived downdrift beaches of sand, and major erosion has occurred. The net alongshore sand transport is from east to west, so this has adversely affected the county park beach between the westernmost groin and the inlet. The shore, dune, and buildings fronted by the 15 groins have had a high level of protection from a number of storms, some very severe (including the Halloween 1991 storm and the December 10-12, 1992 northeaster; Nersesian et al., 1992~. This section of the barrier island had a history of breakthroughs and inlet creation prior to construction of the project (Figure D-12. There are six groins along the beach at Atlantic City, New Jersey, and a modified jetty at its north end. These were planned as a part of the beach nounsh- ment project (Weggel and Sorenson, 1991~. As Weggel and Sorenson state: Historically, shore stabilization structures have contributed to the relative stability of Atlantic City's beaches. Prior to the construction of inlet and beach stabilization structures, Atlantic City's inlet and ocean shorelines experienced large-scale, erratic fluctuations as the inlet migrated. Compared with the pre- stabilization fluctuations, current shoreline changes are small. Inlet stabiliza- tion, initially by bulkheading and groins and subsequently by construction of the Oriental Avenue and Brigantine jetties, is perhaps the most significant ele- ment contributing to beach stability in Atlantic City. The groin and jetty modifications undertaken by the State of New Jersey in 1984 appear to have improved the performance of the 1986 fill when compared with earlier fills. Raising the crest elevation of the jetty has retained fill and prevented its return to the inlet by overtopping and by deflation. Extending the Illinois Avenue groin appears to have resulted in a beach that is about 100 feet wider near Profile 5 at Indiana Avenue. Similar, though less dramatic improve- ments occurred in the vicinity of the other improved/repaired structures.

APPENDIX D rat it I WESTHAMPTON _ ~ ~ ,_ Quantuck Canal Am_ _~c ~[\ HOW. Bride Ct ~5~ __ r::ll ~' 1 ~C2ri^~= ~ 1944 A_ _ _ A. 1 950 221 1 954 Sk ~ in_ - ~ -~ ~ 1 958 fit _ i\ ~ C(t _\ ~ 1 962 Atlantic Ocean I ~I ~ I I I I I I I · I I I Groin 15 Groin 11 Groin 1 GROIN FIELD NOTE: Groins 12 through 15 not constructed BREAK INLET 1000 500 0 500 1000 tIlll1....1 1 1 Scale in Meters FIGURE D-12 Historic barrier island breaching and inlet creation near Westhampton, Long Island, New York. From 1963 to 1967, the city of Deerfield Beach, Florida, built a series of relatively short, low-profile groins with rock mounds at their seaward edge. Al- though these groins are short, they have effectively trapped sand in the along- shore drift without significant downdrift impacts. Sand-Tight Jetties The concept of using long shore-normal structures to create compartments (relatively short "littoral cells," or "pocket beaches") has been considered a num

222 BEA CH NO URISHMENT AND PROTECTION her of times. Under what conditions they might be successful and how to ensure they will function as planned are not clear. Nearly all projects that are combinations of sand-tight jetties and beach nourishment exist because of jetties already in place for navigation purposes. The jetties, and the entrances they fix, may well be the cause of the erosion downdrift, which is why beach nourishment is needed at the site. There is some evidence that a sand-tight jetty (or long groin) can help establish a compartment for the sand fill (Egense and Sonu, 19871. It may be necessary to design, construct, and operate a sand bypass system as a part of the project. There are three sand-tight jetties in the Dade County, Florida, project (Wiegel, 1992a). One, the north jetty at Government Cut (the entrance to the port of Miami), is at the south boundary of the sand fill. The other two are the jetties at Bakers Haulover Inlet, located 15 km north of the cut, about two-thirds of the distance to the Dade County-Broward County line. The north jetty of the cut was originally not sand tight but was made fairly so during its 1986 rehabilitation. The south jetty of the Bakers Haulover Inlet has its outer 91 m curved southwardly to deflect alongshore currents to the south and encourage a gyre to dissipate these currents and minimize sand loss (von Oesen, 1973~. It was completed in July 1974. The north jetty of the inlet was rehabilitated in 1986, making it sand tight, raising its crest elevation, extending its length to 130 m, and constructing a 30-m- long "dogleg" toward its north end. The dogleg was used as a result of a hydraulic model study by the University of Florida (19591. These sand-tight structures seem to have served their secondary purpose of compartmentalizing the beach. Doheny Beach State Park, California, is a sand fill between the east breakwa- ter of Dana Point Harbor and the north jetty (called a groin locally, the purpose of which is to train the river flow to the ocean when floods cut a breach through the beach). The harbor and beach are located at the updrift end of the oceanside littoral cell. The rubblemound jetty is sand tight because its center is constructed of concrete sheet piles. The sand fill was placed in 1964, and the original jetty was constructed at that time. A pocket beach was formed that is still in place and heavily used. It is about 425 m long, and 72,000 m3 of sand fill was placed (Price, 19661. Prior to the fill the surface was basically rock and cobbles, although a sand beach forms whenever the winter runoffs of the creek are heavy. Rock and cobbles can be seen at the present time seaward of the beach at low tide (Wiegel, 1993b). Probably owing to this and the wave climate at the site, little sand is transported through or around the east breakwater and lost into the harbor. Revetments, Seawalls, and Bulkheads There are a number of examples where revetments, seawalls, and bulkheads have been constructed for protection of buildings, walkways, streets, and utilities prior to the use of beach nourishment and then left in place after a fill has been made. Locations where this approach has been used include Miami Beach and

APPENDIX D 223 Redington Shores, Florida. If the structures are well designed, well built, and well maintained, they can provide a backup to the major protection provided by the sand fill. This is important because of the episodic nature of coastal forces (such as waves, storm surges, currents) and an inability to predict future episodes reliably from data obtained from short-term studies. Galveston, Texas, presents a different category. Grade raising, seawalls, and embankments provide the primary protection of the city from hurricane storm surges and waves (Wiegel, 1991~. The purpose of a new beach nourishment project is to provide a recreational beach. There are a few cases where a revetment, seawall, or bulkhead has been designed and constructed as an integral part of a project. The beach nourishment and storm protection project on Fenwick Island at Ocean City, Maryland, nearly 11 km long, was completed in 1991 with about 5 million m3 of sand placed. A 1.3-km-long seawall was built along its southern end to protect the boardwalk. The project was constructed in two separate phases. The sand (0.30 to 0.35 mm median diameter) was obtained from two offshore borrow areas, pumped to shore, placed subaerially, and redistributed by use of bulldozers. The state of Maryland placed a recreational beach fill of 2 million m3 of sand between 3rd Street and the Maryland-Delaware border. This was intended to widen the beach (above mean high water) by about 18 m. Two years after the placement, the severely eroded area between 74th Street and 86th Street was found to be signifi- cantly narrower than 18 m. This was probably due to preproject profile steepen- ing, which would have required more volume to provide 18 m of widening. Then, during 1990-1991, the USACE placed 4 million m3 of sand. This was for storm protection and included a sand dune between 27th Street and the border with Delaware, and a concrete-capped, steel-sheetpile bulkhead along the seaward edge of the boardwalk from 3rd Street to 27th Street, with a berm in front of both. The second project described herein is at Bate Bay, New South Wales, Australia, 25 km south of Sydney Heads. It is a crescent-shaped bay with a 5.5- km shoreline. It is being described here for four reasons. One is that it is a hybrid project, with a 340-m-long seawall constructed along part of the project (Prince Street) with a walkway along its crest (Hirst and Foster, 1987~. The second is that about 10 metric tons of dyed sand was placed in the surf zone at the updrift end of the bay and tracked for several months. The third is that the sand sink is wind- blown sand, transported inland into dune fields (much of the sand in the central portion of the back-dune region has been mined over the past 40 years for con- struction and foundry uses). The fourth is that a new equilibrium seems to have been developed, reducing substantially the loss of sand inland owing to the refor- mation of dunes, vegetation, and the resulting moderation of wind action and sand washouts (Gordon, 1994J. There was severe erosion and changes in beach orientation in the Sydney region that took 3 to 5 years to recover, with foredunes taking about 6 years. There has not been as severe a sequence of events since

224 BEA CH NO URISHMENT AND PROTECTION (Gordon, 1994). Much of the erosion of Bate Bay beaches occurred during a series of severe storms in May and June 1974 (Gordon, 19921. Using calculations of estimated littoral drift (net transport from south to north in most of the bay) and sand blown inland into dune fields, profile measure- ments, aerial photographs, wave data, and sand tracer studies, it was concluded that Bate Bay was a closed system, with the loss of sand (the sink) being inland along the center portion of the bay at an average rate of about 46,000 m3/year. This was because the foredunes had degraded substantially, with washouts (troughs) and blowouts (Gordon, 19941. A mathematical model was developed and applied similar to the GENESIS model developed later at CERC (Gordon, 19943. The gross alongshore transport in the southern third of the bay was esti- mated to be 700,000 m3/year with a net of 41,000 m3/year (only about 6 percent of the gross) toward the north. Along the central third of the shore, the estimate of gross transport rate was 165,000 m3/year with a net of 21,000 m3/year toward the north. Along the northern third of the shore, the estimate was 86,000 m3/year with a net of only 1,200 m3/year toward the south. The net transports are all small differences of relatively large estimated quantities of gross transport. The management plan adopted was to establish a well-vegetated foredune along much of the bay and: . . . rather than mechanically forcing a new shoreline alignment on the embay- ment, the technique used involved: the establishment of some initial dunes on the existing alignment; feeding of the surf zone with nourishment sand; allow~ing] the natural processes to distribute the material throughout the em- bayment and also allocating] these processes to adjust foreshore/dune align- ment and the offshore seabed. After this was done, the back dunes in the center of the embayment would be stabilized. Remedial work was taken along the center reach of the foredunes, installing sand-catching fences, beach access tracks, infilling blowouts and washthroughs, and planting dune-stabilizing vegetation. Then in 1977 and 1978 about 80,000 m3 of sand was hauled by trucks from the inland portion of the dunes to the south end of the bay (at South Cronulla) and spread by bulldozer. After the 1978 swimming season, another 47,000 m3 of sand were transported and placed, for a total of 127,000 m3. In 1985, the 340-m-long seawall and walkway were constructed. The project has been monitored since completion and found to be effective (Gor- don, 19921. The rebuilt dunes and vegetation have caused the sand to be depos- ited on the seaward face and become a part of the foredune system. This has also changed the local wind patterns in the beach and dune area, and there has been a progressive decrease in the amount of sand blown inland. The project has been subjected to a number of major storms since completion, although none as severe as the 1974 storm. South Cronulla Beach has been slowly eroding but after 15

APPENDIX D 225 years is still in usable condition, and no renourishment has been required. It has performed as expected (Gordon, 1994~. In the management plan it was recognized that if the beach were subjected to a series of storms similar to those of 1974, it would be expected that substantial erosion would occur and that it would be within the project fill but would require rebuilding of the foredunes and beaches (Gordon, 1994~. Submerged Sill (Perched Beach) A beach nourishment and submerged sill (perched beach) project was con- structed in Italy between mid-1989 and mid-1991 along 3 km of coast at Lido di Ostia, about 35 km from Rome, on the Tyrrhenian Sea. This is on the Tiber River Delta, which in recent decades has been eroding at a recession rate of about 1.7 m/year owing to a major reduction in sand transported to the coast by the river due to dams and the mining of building material from the river bed (Ferrante et al., 1992~. The rubblemound submerged sill was constructed parallel to shore, about 150 m from it, in water about -4.0 to -5.0 m below mean sea level, appar- ently located where there was a natural sand bar. It has a 15-m-wide crest at -1.5 m below mean sea level, with a seaward slope of l(V)ertical to 5(H)orizontal. The maximum weight of the stone is 1 metric ton, and there is a 5-m-wide rock toe protection in a 1-m-deep trench. The stone was placed on a geotextile base. For safety the location is marked with buoys. The fill was a double layer of quarry material, the thick lower layer a mixture of sandy gravel, poorly sorted (0.08 to 120 mm), with a 1-m-thick layer of sand (0.3 to .3 mm) placed on top. The berm crest was located at +1.0 m above mean sea level, and the seaward slope was about 2.5 percent. The new shoreline was about 60 m seaward of the then- existing location. About 1,360,000 m3 of sand and selected sandy gravel were used for the beach, and about 300,000 m3 of rock (basalt and limestone from different quarries) was used for the sill. The project has been monitored during the 3 years since completion and has performed reasonably well while subjected to a number of severe storms. The elevation of the berm increased to +1.5 to +2.0 m above mean sea level, and the submerged profile deepened. Minor scour occurred seaward of the barrier toe. No adverse effects were observed on adjacent beaches. Subsequent to Ferrrante et al.'s 1992 paper, an additional kilometer of submerged sill was constructed in shallow water, closer to shore. This change in location was made based on observations of the performance of the first project. The new sill has performed in a more satisfactory manner, with sand moving in from the first beach fill, forming a wider beach along the section of coast in the lee of the new sill (Tomasicchio, 1994~. A 400-m-long artificial beach was constructed on the Mediterranean Sea coast at Monaco during 1965 to 1967. Three 80- to 100-m-long breakwaters were built with 80-m gaps between them, in water 6 to 10 m deep. Two were shore parallel and connected to it by groins made of concrete blocks. The third (west

226 BEACH NOURISHMENT AND PROTECTION breakwater) was connected to the shore. A sill was constructed across each of the gaps, with tops at -2.5 m below datum and backfilled with quarry-run rock. The fill was 80,000 m3 of local dolomite chippings that had a median diameter of 3 to 8 mm (gravel) (Tourman, 1968~. The project has performed in a satisfactory manner, requiring only about 5,000 m3 of replacement gravel during 23 years (Rouch and Bellessort, 1990~. RISK ASSESSMENT The terms "risk assessment" and "risk analysis" are usually associated with the decision-making process for projects or practices where the potential for adverse environmental consequences or loss of life is high. In recent decades, risk assessment studies have dealt with the probability of occurrence of catastrophic events in the design of nuclear power plants, with public health issues such as the risk of smoking and exposure to carcinogens, and with studies of terrestrial and aquatic systems (Cohrssen and Covello, 1989~. Good engineering design has always addressed the effects of unusual events on the performance and survival of engineering projects. This has been particularly true for civil engineering projects, where natural forces often present critical design conditions. Beach nourishment projects are no exception. Calculating the risk that a specific project will be damaged or will cause damage can be difficult because establishing the level of acceptable risk involves socioeconomic trade-offs for which there are no simple formulas. Often, deci- sions involving risk are based on emotion or judgment more than on an actual quantification of the risk. Because beach nourishment projects often have rela- tively short renourishment cycles, the public may perceive them as failures and as economically risky when, in fact, they are economically justified. For beach nourishment projects, there are two problems for which risks might be evaluated. These are (1) the risk that a project will bring about adverse biological effects at the beach or borrow site and (2) the risk that a project will not perform as anticipated. The following discussion deals only with this latter risk. Beach nourishment projects provide protection even when subjected to events that exceed their design level (see Appendix H). A project designed to protect against storm criteria with a 100-year recurrence interval will provide protection to some extent against storm criteria with a 200-year recurrence interval, al- though some damage will occur. Generally, there will be a low-level storm that will not cause any damage. However, a protected area may still sustain some damage during storms with a return period less than the storm criteria upon which the design was based. Even after a project has sustained some damage, most of the sand associated with the project usually remains immediately seaward of, or in close proximity to, the project area and continues to provide some level of protection. The elements of risk analysis include:

APPENDIX D 227 · hazard identification defining those hazards that could possibly result from a beach nourishment project and those to which a beach nourish- ment project might be subjected; risk assessment a definition of the severity of the risk, the probability of an event's occurrence, and the consequences of that event's occurrence; · significance of risk how the designer, client, and public perceive the risk and how much risk is acceptable; and decisions how the risk analysis will influence decision making in the design process, in scheduling and construction, and in the operation of a project. . . In many cases, there is a paucity of data on which to base decisions that might minimize risk. Engineering always requires making decisions with incom- plete data but strives to minimize the probability of failure or loss using the data that are available. Risk Considerations in Beach Fill Design The purposes of performing a risk analysis for a beach nourishment project include: · identifying the physical and biological problems associated with beach nourishment, · comparing technologies to determine their relative effectiveness in reduc- ing the risk associated with beach nourishment projects, and · setting management/operation priorities or selecting from among several actions. The first step in risk assessment is to identify what events could possibly occur during a beach nourishment project's lifetime and then to quantify their severity and the consequences of their occurrence. Events can be classified as those that result in economic loss and those that are likely to result in loss of life. The latter are more critical but fortunately occur rarely in the case of failure of a beach nourishment project. Possible events include large waves, elevated water levels, and high alongshore transport rates. The likelihood that a given event will occur is generally expressed in terms of a probability distribution. For example, wave heights and other extreme events frequently follow an Extremal Type I (Gumbel) distribution or other typical distributions for extreme values (see Fig- ure D-131. There are various levels of sophistication by which risk can be incorporated into a beach nourishment project design:

228 5 4 - C) 3 _ LL I ~ 2 _ O .0001 .0005 .001 .002 BEA CH NO URISHMENT AND PR O TECTI ON 90% Confidence Limit 90% Confidence Limit ~~ . , . . . 1 1 1 1 1 1 1 1 11 1 1 11 1 ~ 1 1 1 .005 .01 .02 .05 .1 .2 EXCEEDANCE PROBABILITY .4 .6 .8 .1 0 FIGURE D-13 Extremal Type I (Gumbel) distribution for annual maximum wave height statistics based on hindcast data for Atlantic City, NJ. (Jensen, 1983~. . . . Deterministic design uses a probabilistic description of the physical envi- ronment. This assumes a reasonable set of design conditions based on knowledge of the physical environment and tailors the design to that environment (e.g., design for the 100-year or 1,000-year storm). Probabilistic design considers the uncertainties in describing the physical environment. This approach develops the statistics of various events (e.g., high water levels, extreme wave heights, storm durations) and optimizes the design to minimize economic risk. The design wave height and water level that produce the maximum net benefits for the project are selected. Stochastic design or simulation includes procedures to generate one or more time series of data based on measurements of the physical environ- ment at a project site. For example, an artificial wave environment having the same statistics of the real wave environment at a beach fill site may be generated synthetically. Based on knowledge of the physics of coastal processes important to the performance of beach nourishment projects, the synthetically generated data series is used to evaluate the response of the project for many possible, statistically similar scenarios. From the many simulations, the range of possible responses of the project to the  environment is statistically defined. This constitutes an analysis of many simulations of a project's response to many statistically similar environ- ments in order to define a range of possible outcomes.

APPENDIX D 229 As knowledge of coastal processes and the ability to describe them math- ematically increases, design will rely more and more on computer simulations. Simulation as a design process requires: · knowledge of, and the ability to quantitatively describe, the physical envi- ronment at a site and · understanding of, and the ability to numerically model, the important coastal processes. Risk Relative to Storm Intensities and Nourishment Intervals For any beach nourishment design, there is a risk that storm intensities and durations will exceed those for which the project was designed. Assessment and quantification of this risk are important parts of the design analysis and the public information program. For beach restoration, there are basically two design ele- ments for which risk needs to be considered separately. The first is the risk that the design cross-section that provides storm protection for upland properties could be impacted by a major storm. In that case, the larger storm could erode the entire profile, leaving upland structures vulnerable to undermining and wave impact. This is the risk that upland damage would exceed acceptable levels and that the project will require emergency repair. A safety factor that would increase the size of the selected design cross-section could be used to decrease the risk of emergency action. The second risk concerns the renourishment interval. If weather conditions following a nourishment are generally stormier than average conditions or if portions of the project erode significantly faster than expected at hot spots, the time between renourishments may be shorter than the programmed postnourish- ment time period. It is also possible that the amount of offshore adjustment will exceed the design expectations, leaving a less-than-desired dry beach area a common problem in the first nourishment that would also necessitate earlier renourishment. This constitutes a risk of having to nourish a beach earlier than programmed and, if significantly in advance of the planned renourishment, could strain a local sponsor's financial resources for cost sharing. A substantially shorter interval than programmed could also lead to a public perception that the project is not performing properly. Therefore, the implications of shorter nourishment in- tervals need to be properly estimated, incorporated into the economic analysis and local funding plan, and communicated to all concerned, including the public. In practice, because of limitations in a local sponsor's financial ability to support renourishment when first needed, the programmed time interval for renourishment is often followed despite increased vulnerability as the result of excessive ero- sion. When renourishment is not timely with respect to maintaining designed levels of protection, some of the shore protection benefits may not be realized if

230 BEACH NOURISHMENT AND PROTECTION significant storms are experienced before renourishment actually occurs. It may be appropriate to increase advanced-fill quantities beyond those actually required in order to lower the risk of a shortened renourishment interval (or increased vulnerability to storms). A programmed shorter first renourishment interval would also help address the uncertainties of hot-spot erosion and offshore adjustment. Sample Calculation of Probability for a Storm Return Period The probability that an event with a given return period will be equaled or exceeded in a given period of time (usually the project's lifetime) can be esti- mated by the following equation: R = 1 - (1 --~ ~ TJ (D-3) where R is the probability that an event equal to or greater than the design event will occur at least once in n years (risk), T is the return period of the design event in years (the reciprocal of the probability that the event will be equaled or ex- ceeded in any one year), and n is the number of years. Consequently, if a nourish- ment project with a proposed lifetime of 10 years is designed for a 100-year storm, the risk of a 100-year storm occurring at least once in that 10-year period IS: R = 1 _ :1- 1 ) = 0.096 (D-4) or about a 10 percent chance. The risk that a 10-year storm will occur at least once in a 10-year period is R=1-~1- 1) =0.651 (D-5) or a 65 percent chance. The risk equation is derived from the binomial probability distribution for 1 minus the probability that the event will not occur at all in n tries. This procedure assumes that the environment is known well enough that a statistical distribution can be developed for the event's occurrence. The magnitude of the design event is generally found from a statistical analysis of measured data to give an estimate of the event's probability distribu- tion. Figure D-13 shows a typical plot of wave height versus the estimated prob- ability that the given wave height will be equaled or exceeded. In the figure the

APPENDIX D 231 wave height that will be equaled or exceeded once in a 100-year period (the 100- year event or the event that has a probability of 0.01) is 4.6 m. Water-level data alongshore sand transport data, and other parameters might also be analyzed in the same manner. One complicating factor in this approach and in those discussed below is the question of how well the physical environment is known and how well it can be described. Probability distributions constructed for wave heights, periods, water levels, and so forth, are merely approximations of the true population. More sophisticated analyses can include the uncertainty in defining these distributions (USAGE, 1992b, 1993~. Probabilistic Design Another type of design is termed "probabilistic design." This approach evalu- ates the economics of building projects at various scales. As the scale of a project increases, the level of protection it provides and the economic benefits also increase, so that protection is provided against more severe conditions; however, the cost of providing this additional protection also increases. For a beach nour- ishment project, the project's scale might be indicated simply by the berm width or by the volume of sand per unit length of beach. Damages at various project scales are determined by using the probability that the design conditions will be exceeded. Figure D-14 shows the various economic elements of the probabilistic design procedure for a range of beach berm widths. For a narrow berm (or, alternatively, for a low volume of sand per unit length of beach), annual damages to the backbeach area will be high. As berm width increases, annual damages decrease, since the wider berm provides more protection. Also, as berm width increases the recreational area, benefits may increase. Project costs also increase with beach berm width, since more sand must be placed. The cost of replacing lost sand from the project to maintain a given level of protection initially in- creases for narrow berm widths but levels off for wider berms. The level of design selected is the berm width that minimizes the net annual cost or maximizes the net benefits. The damages decrease for larger berm widths, since the probabil- ity of occurrence of storms large enough to erode the beach gets smaller. It takes larger, less frequent storms to destroy a protective beach with a wider berm. In the case of beach nourishment the analysis is further complicated by the fact that~the berm width, and hence the level of protection, is a function of time. For example, during the second year following construction, the level of protec- tion will generally be reduced because of any losses experienced by the project during the first year. During the third year, the protection will be further reduced; consequently, not only is the magnitude of a storm important but also when in the renourishment cycle it occurs. Figure D-15 shows how damages to backbeach areas might vary with berm width at the start of a storm and the wave conditions characterizing the storm. For increasingly wider berms, waves cause progres

232 a o _ _ BEACHNOURISHMENT AND PROTECTION \ \ Annual Damages Without Project _ - of< Total Cost - Annual Damages  With Project - - - Recreation Benefits Foregone ~ - Annual Cost of Project E m c' 2 _ E E _ Q - DESIGN BERM WIDTH FIGURE D-14 Various economic elements of the probabilistic design procedure for a range of beach berm widths. sively less damage. Application of this information requires that the berm width be known as a function of time. The berm width at any time depends on anteced- ent events and ideally should be defined statistically; however, an expression for average berm width as a function of time, if available, can be used. Figure D-16 presents the same information as Figure D-15 but in a different way. Here backbeach damage is plotted against wave height for various berm widths that could exist at various times during the renourishment cycle. For a given charac

APPENDIX D 6 233 \ B = Berm Width at Start of Storm B = Be - xt Be= Design Berm Width x = Average Annual Erosion Rate t = Time in Years BERM WIDTH AT START OF STORM FIGURE D-15 Annual damages as a function of significant wave height and berm width at the start of a storm. teristic wave height (or some other measure of storm intensity), there is a berm width that will completely protect the backbeach area. Waves larger than this zero-damage wave height will result in some damage. The risk of experiencing backbeach damage increases with time because of the beach erosion inherent in those areas where beach nourishment is needed. It is important to recognize that damages do not depend simply on wave action but also on other factors such as water level and storm duration. There is currently no single simple parameter to describe the effect of storms on beach nourishment projects. Risk Determination by Simulating the Performance of Beach Fills Because of the stochastic nature of the coastal environment and the response of beach nourishment projects to that environment, the sequence in which events occur and the condition of the beach nourishment project at the times those events occur are important. Consequently, simulation of the performance of beach nour- ishment projects holds the promise of quantifying risks associated with such projects. Simulating the performance of proposed beach fills requires that a long time series be generated of the physical events-storms, waves, and water levels that could occur during the lifetime of a fill. The synthetically generated time series must have the same statistical characteristics as the real environment. The

234 BEA CH NO URISHMENT AND PR O TECTI ON ~_ LL Zero Damage Wave Heights it/ WAX/ "" ~ ~,,~k - - SIGNIFICANT WAVE HEIGHT FIGURE D-16 Annual damages as a function of significant wave height and benn width. Berm width is a function of time since the last renourishment. response of the beach fill to many possible enactments of that environment is determined and statistically summarized. Answers are sought to such questions as: How many times and how much damage will occur? How will the beach width vary with time? What range of beach widths might prevail 2, 3, or 4 years following nourishment? In effect, simulation will provide a range of possible outcomes or responses to building a beach fill at a given site. Simulation requires extensive data on the physical environment at a site, specifically, information on waves (height, period, direction), water levels, storm durations, and their joint probability distributions. Simulation also requires that the important coastal processes involved be understood and amenable to quanti- tative description. Further confidence is required in the results of the simulations, and funds are available to run enough of them to obtain reliable statistics. Simu- lations using synthetic data have been used for decades in water resources engi- neering to optimize reservoir operating plans and to design reservoir systems (Fiering and Jackson, 1971~. There have been few coastal engineering simulation applications, mainly because of the complexity of the processes involved and the paucity of good data on the physical environment. In recent years, however, progress has been made in the development of computer models of the relevant coastal processes, and several simulations have been made. Weggel et al. (1988) statistically described the alongshore sand transport environment from wave hindcasts and then used synthetically generated alongshore transport data to simu- late the operation of a sand bypassing plant at Indian River Inlet, Delaware.

APPENDIX D 235 Strine and Dalrymple (1991) simulated the performance of a beach fill on the Delaware coast using synthetic wave data based on wave hindcasts. One result of numerous simulations is statistical information on when re- nourishment will be necessary. The length of the renourishment cycle can be established in a statistical sense if a given berm width is to be maintained. In addition, input to a "project operating plan" can result from simulations. Simula- tions can provide information on what conditions in the project should trigger action. For example, when the shoreline recedes to a given width in a specified month, renourishment is needed to provide the desired level of protection. BEACH NOURISHMENT AND THE BUDGET OF LITTORAL SEDIMENTS Beach nourishment can be viewed as a human intervention into the overall budget of littoral sediments, in many cases in response to adverse impacts on the natural system. The budget of sediments is simply an application of the principle of conservation of volume to the littoral sediments. The time rate of change of sand volume within the system is dependent upon the rate at which sand is brought into the system versus the rate at which sand leaves. The budget involves assessing the sedimentary contributions (credits) and losses (debits) and equating them to the net gain or loss (balance of sediments) in a given sedimentary com- partment (Bowen and Inman, 1966; Komar, 19761. The balance of sediments between the losses and gains should be equal to the local beach erosion or accre- tion. Table D-1 summarizes the possible sources (gains) and sinks (losses) of sand for a littoral sedimentary budget. In general, alongshore movements of sand into a littoral compartment, river transport, and seacliff erosion provide the major credits; alongshore movements out of the compartment, offshore transport (espe- cially through submarine canyons), and wind transport shoreward to form sand dunes are the major losses or debits. As listed in Table D-1, beach nourishment TABLE D-1 Budget of Littoral Sediments Credit Debit Balance Alongshore transport into area River transport Sea-cliff erosion Onshore transport Biogenous deposition Hydrogenous deposition Wind transport onto beach Beach nourishment Alongshore transport out of area Wind transport out Offshore transport Deposition in submarine canyons Solution and abrasion Solution and abrasion Mining Beach accretion or erosion SOURCE: After Bowen and Inman ( 1966).

236 BEACH NOURISHMENT AND PROTECTION 38,000 m3/yr 200,000 martyr Ediz Hook FIGURE D-17 Sand sources for Ediz Hook, Washington, spit (from Galster and Schwartz, 19901. represents a credit, the volume of which is intended to shift the balance of the overall budget from erosion (a net deficit) to shoreline accretion (a positive balance). The role of beach nourishment as a factor in the budget of sediments is illustrated by Ediz Hook on the Strait of Juan de Fuca coast of Washington (Figure D-17. The spit, composed mainly of gravels and cobbles derived from the Elwha River and cliff erosion into glacial outwash sediments, was formed by the eastward alongshore transport of those sediments (Galster and Schwartz, 19901. Erosion of Ediz Hook began early in the century as the river was dammed, cutting off its estimated supply of 38,000 m3/year of sediment to the littoral zone, and then by the construction of a bulkhead along the eroding sea cliff, depriving its 200,000 m3/year sediment contribution. Not unexpectedly, Ediz Hook began to erode, with the erosion being a maximum at its western end, while the terminal end of the spit continued to grow toward the east. The maintenance of Ediz Hook is important because it forms the natural protection of Port Angeles Harbor. The response to the growing erosion problem was the construction of a revetment along the length of the spit, together with nourishment of the fronting beach (Galster and Schwartz, 1990). The initial nourishment involved placement of gravel and cobbles, derived from inland sources, along the length of the spit. It is apparent, however, that nourishment might be more effective if placed at the western end of the spit as a feeder beach, basically replacing the sediment that was formerly contributed by the natural sources. The situation at Ediz Hook provides an excellent example that beach nourishment often represents human intervention into the overall budget of littoral sediments. At Ediz Hook, the sediment budget was first affected by cutting off the two major sources, sedi- ments derived from the Elwha River and from sea cliff erosion. Beach nourish- ment represents a further human manipulation of the budget in an attempt to restore those lost sources. This and other examples indicate the need for a broad

APPENDIX D 237 analysis in developing a budget of sediments for the site. This is necessary in order to better understand the basic causes of the erosion and the reasons for needing a nourishment project. VENEER BEACH FILLS Veneer beach fills have been used in situations where beach-quality sand is not available in sufficient quantities to economically undertake a nourishment project. Veneer fills involve placing beach-quality sand over a relatively large volume of material that is generally unsatisfactory for beach nourishment. The unsatisfactory materials, which may either be too coarse or too fine, serve as an underlayer beneath the beach-quality sand. The usual reason for using a veneer fill is economic: the cost of providing a cross-section built totally of beach- quality sand is prohibitive. Veneer fills are of two types: . fills where the underlying materials are coarser than typical beach sands (e.g., boulders, coral, rocks) and · fills where the underlying materials are finer than typical beach sands (e.g., silts or silty sands where the median grain size is much smaller than the native sand). In the United States, veneer beach fills have been used in Corpus Christi, Texas; Key West, Florida; and Grand Isle, Louisiana. At Key West, the underlying material was a coral rock much coarser than typical beach sand. At Corpus Christi, the underlying material was silt or silty sand, much finer than typical beach sand. At Grand Isle, a core of compacted clay was included in the dune cross-section as a barrier to erosion if the sand veneer is eroded to expose the core. A fundamental design problem associated with veneer fills is selecting a veneer that is sufficiently thick so as not to erode away and expose the core during storms or before scheduled replenishment. From a shore protection per- spective, not making the veneer thick enough poses no particular problem if the underlying material is coarser than the sand veneer. Erosion of the veneer ex- poses the coarse underlayer, which is more resistant to erosion. However, the veneer might have to be replaced before recreational benefits can again be real- ized. Conversely, for the situation where finer underlying material is used, if the veneer erodes, the underlying fine material will be exposed to wave action to erode more quickly and reduce the level of protection afforded by the fill. The design of veneer fills with fine underlying material requires knowledge of the seasonal and storm-induced profile changes along with knowledge of prevailing background erosion rates. The thickness of the veneer must be suffi- cient to provide an envelope to these profile variations and to the background

238 BEACH NOURISHMENT AND PROTECTION 1 1 Dune Beach Inner Bar Outer Bar _ ~ Shoreface -10 Owl Profile Line 62 297 Surveys 20 Jan 81 to 18 Dec 91 Profile Line 188 285 Surveys 26 Jan 81 to 18 Dec 91 1 1 1 1 1 1 1 0 100 200 300 400 500 600 700 800 900 1000 DISTANCE (m) FIGURE D-18 Profile envelopes showing depth of profile changes (from Lee and Birke- meier, 19931. erosion if the underlying fines are not to be exposed during storms or before scheduled renourishment. Because of these constraints, veneer beach fills with underlying fines are less likely to be used on beaches exposed to large waves or beaches that experience a large tidal range. One procedure that can be used to select a veneer thickness involves plotting many historical beach profiles for a proposed fill site on a single axis system and constructing an envelope to the profiles (see Figure D-183. This gives an indication of the required thickness of the sand veneer on a beach profile involved in seasonal profile excursions. The thickness found in this way provides a lower limit on the required veneer thick- ness. Similar plots for storm-induced profile changes, while often difficult to obtain, are needed to determine the depth of profile changes that might occur during storms. Selection of a design storm is thus also critical for a veneer's design. The selection of a veneer thickness for fills with coarse underlying materials is less critical. The same procedure outlined above can be used to select the thickness. In some sections of California the natural sand veneer over cobbles or bedrock is removed after storms and during the winter but returns in calmer weather.

APPENDIX D Corpus Christi, Texas 239 Beach Veneer Experience In 1978 a veneer beach fill was constructed at Corpus Chnsti Beach in Corpus Chnsti Bay, a sheltered area of relatively low wave action (Kieslich and Brunt, 19891. The tidal range at the site is less than 0.1 m. The project area had experienced erosion since the late 1800s. About 380,000 m3 of a silty-sand mate- nal was dredged from Corpus Chnsti Bay and placed as an underlayer along the 2.3-km-long project area. Subsequently, 230,000 m3 of coarse (median diameter, 0.4 mm) beach-sized material was trucked in and placed as a veneer. The 230,000 m3 of veneer sand included 96,000 m3 for 5 years of advanced nourishment to combat an estimated loss rate of 19,000 m3/year (see Figure D-l9~. The thickness of the veneer varied from 0.5 m on the berm to about 1.0 m on the foreshore. The project was completed in March 1978 and has performed well. The loss rate actually experienced has only been about 13,000 m3/year. The project was inun- dated during Humcane Allen in 1980, which created an 2.4-m surge in Corpus Christi Bay near the beach. Consequently, the project was under about 1.5 m of water and so was cushioned from direct hurricane wave attack. The beach lost 1.5 to 0.5 at ~0 J 'a -0.5 -1 .0 -1 5 . , Berm _ | Foreshore | 30 m min.: 35m+ .. ~ . . ~-+1.0 · .~ · W _., mhw 0.2 m msl ~-W ~ c \,~ -06 Existing ~ - , _~ 1 1 1 1 1 0 50 100 150 200 DISTANCE (m) FIGURE D-l9 Veneer beach fill cross-section, Corpus Christi Beach, Corpus Christi, Texas.

240 1.0 0.5 z o o us ~,~ 0.5 -1 .0 -1 .5 -2.0 _ 1 BEACH NOURISHMENT AND PROTECTION . ~ m "I Rock C: Existing Bottom 1 . =12 mail 1 1 0 20 40 60 80 100 120 DISTANCE (m) FIGURE D-20 Veneer beach fill cross-section, Key West, Florida. about 6,000 m3 of sand as a result of Hurricane Allen. The north end of the project continued to experience erosion, as evidenced by the growth of a spit there. As a result of this erosion, a terminal groin was constructed in November 1985 to stabilize the north end of the fill. Key West, Florida . A protective and recreational beach was constructed along the south shore of Key West by excavating a trench 2 m deep and 12 m wide in offshore relict coral and placing the rock material on the beach as an underlayer (USAGE, 1957, 1982a). A veneer of calcareous sand was placed on top of the rock underlayer. The offshore trench was excavated, and the excavated material was used as the base for the beach fill. (See the project cross-section depicted in Figure D-20.) The project was authorized in 1960 and involved the improvement of 2,000 m of beach (termed "smothered beach") along the south shore of Key West along South Roosevelt Boulevard. The project area is exposed to ocean waves but is somewhat protected by a coral reef some 8 km offshore. The mean tidal range is 0.4 m and the spring range is 0.5 m. Approximately 64,000 m3 of rock was excavated and covered by a 0.6-m-thick blanket of beach sand obtained offshore by dredging a nearby navigation channel. Approximately 103,000 m3 of blanket material (veneer) was used. The native beach material, when present, had a

APPENDIX D 241 median diameter ranging from 0.07 to 1.00 mm, with the finer materials coming from offshore. Veneer sand from two borrow area sources had sizes ranging from 0.24 to 1.00 mm. The bottom of the deepened offshore trench was also covered with a 0.6-m blanket of sand to an elevation of -0.6 m to serve as a bathing area. The slope of the trench on its seaward side is 1V (vertical) to 2H (horizontal). The elevation of the rock core beneath the berm is +0.6 m, while the sand blanket (veneerJ is 0.6 m thick and extends up to an elevation of +1.2 m. The width of the berm is 30 m, and the beach slopes seaward at 1V to 20H to the bottom of the trench. The beach in the project area is backed by a concrete seawall with a crest elevation of +1.8 m. The bottom elevation seaward of the trench is only about -0.3 m, so the constructed trench actually serves as a bathing basin. The project design anticipated a loss of about 15,000 m3/year of veneer sand, of which approximately 7,500 m3 was expected to be lost offshore to the trench while the other 7,500 m3 would be lost by alongshore transport from the project area. Project operation called for retrieving 23,000 m3 from the trench every 3 years and returning it to the beach. Every 6 years an additional 46,000 m3 was to be obtained from other sources, presumably offshore, to restore the beach. The offshore sands have not been used to date because the erosion occurred more slowly than expected. Grand Isle, Louisiana Grand Isle is a low-lying Mississippi River delta margin barrier island ap- proximately 12 km long, located 95 km south of New Orleans in Jefferson Parish (Combe and Soileau, 1987; Combe, 19933. Following Hurricanes Flossy (1956), Carla (1961), Betsy (1965), and Carmen (1974', all of which damaged Grand Isle, Congress authorized a beach nourishment and hurricane protection project. In 1983-1984 the USACE reconstructed the beach and dune using 1.8 million m3 of sand dredged from two offshore borrow areas. The material dredged from the offshore borrow areas was stockpiled between the shore and a shore-parallel dike and allowed to drain. The fill contained significant amounts of silts and clays; consequently, the stockpiled material was reworked using bulldozers and dra- glines to speed up drying so that the material could be reshaped into the design cross-section. Winter storms during 1984-1985 resulted in the loss of 175,000 m3 and led to the development of renourishment plans in 1985. However, Hurricane Danny struck in August 1985, Hurricane Elena in September 1985, and Hurri- cane Juan in October 1985, eroding 50,000, 30,000, and 280,000 m3 of sand, respectively, from Grand Isle. Between January and July 1986, an additional 50,000 m3 was lost. Hurricane Bonnie struck in September 1986 but caused little damage to the project; however, storms between July 1986 and February 1987 eroded an additional 95,000 m3. Renourishment was delayed when a storm struck in March 1987. Bids had been received several days earlier for Phase I of the renourishment but were rejected due to the altered site conditions caused by the

242 6 1 r - z 4 _ o 2 _ us J O BEACH NOURISHMENT AND PROTECTION am +3.6mto4.1m NGVD +0 9 m m <am, `~` ,, 1~8m~ . _ +2.3 m to + 2.4 m NGVD 0 5 10 15 20 DISTANCE (m) 25 30 FIGURE D-21 Veneer beach fill cross-section, Grand Isle, Louisiana. storm. Renourishment was finally begun in October 1987 and completed in March 1988. In Phase II of the renourishment project, completed in 1990, 1.1 million m3 was placed on the beach at a cost of $9 million, a clay core built of material excavated from the bay behind Grand Isle was added to the project's dune cross- section, and the dune elevation was raised (see the cross-section shown in Figure D-21~. The compacted clay core is intended to contribute stability to the cross- section by reducing erosion once the core becomes exposed during a storm. The clay core is credited with preventing damage by Hurricane Andrew. Expenditures on Grand Isle to date have been $1.8 million for repairs and $9.0 million for the complete restoration, yielding a total of $10.8 million. Damages prevented by the project are estimated to be $12.5 million. Current plans are to restore the beach and dune and to investigate using nearshore breakwaters to stabilize a portion of the project. Assessment of Veneer Fills Experience suggests that veneer fills with finer underlying materials can work in some low-to-moderate wave environments and low tidal ranges (e.g., in sheltered waters such as Corpus Christi Bay). Their performance in areas ex- posed to large waves and large tidal ranges is less certain. Veneer fills with underlying coarse materials, such as the Key West project, might also work in areas that experience larger waves. There has not been enough experience with fills of this type to say with certainty that they will be successful. Certainly, for the case of coarser underlying materials, erosion rates should decrease if the core becomes exposed; however, recreational opportunities may be lost.

APPENDIX D 243 REFERENCES Allison, M. C., and C. B. Pollock. 1993. Nearshore berms: an evaluation of prototype designs. Pp. 2838-2950 in Proceedings of Coastal Zone '93. New York: American Society of Civil Engi neers. Andrassy, C. J. 1991. Monitoring of a nearshore disposal mound at Silver Strand State Park. Pp. 1970-1984 in Proceedings of Coastal Sediments '91. New York: American Society of Civil Engineers. Bakker, W. T. 1968. The dynamics of a coast with a groin system. Pp. 492-517 in Prc~ceedin,,s of 11th International Conference on Coastal Engineering. New York: American Society of Civil . Englneers. Balsillie, J. H., and R. O. Bruno. 1972. Groins: An Annotated Bibliography. Miscellaneous Paper No. 1-72. Washington, D.C.: Coastal Engineering Research Center, U.S. Army Corps of Engi neers. Beachler, K. E. 1993. The positive impacts to neighboring beaches from the Delray Beach nourish- ment program. Pp. 223-238 in Proceedings of the 6th Annual National Conference on Beach Preservation Technology. Tallahassee: Florida Shore and Beach Preservation Association. Bender, T. 1992. Personal communication, U.S. Army Corps of Engineers, Buffalo District, with R. L. Wiegel. Birkemeier, W. A. 1985. Field data on seaward limit of profile change. Journal of the Waterway, Port, Coastal, and Ocean Engineering 3(3):598-602. Bowen, A. J., and D. L. Inman. 1966. Budget of Littoral Sands in the Vicinity of Point Arguello. California, Technical Memorandum No. 19. Washington, D.C.: Coastal Engineering Research Center, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. Bruun, P. 1962. Sea level rise as a cause of erosion. Journal of the Waterways and Harbors Division 88:117-133. Bruun, P. 1986. Sediment balances (land and sea) with special reference to Islandic South Coast from Torlakshofen to Dyrholarey. River nourishment of shores practical analogies on artifi- cial nourishment. Coastal Engineering 10: 193 -210. Bruun, P. 1988. Profile nourishment: its background and economic advantages. Journal of Coastal Research 4:219-228. Bruun, P. 1990. Beach nourishment- improved economy through better profiling and backpassing from offshore sources. Journal of Coastal Research 6:265-277. Burke, C. E., and G. L. Williams. 1992. Nearshore Berms Wave Breaking and Beach Building. In: Proceedings of Ports '92 Conference. New York: American Society of Civil Engineers. Campbell, T. J., R. G. Dean, A. J. Mehta, and H. Wang, 1990. Short Course on Principles and Applications of Beach Nourishment. Organized by the Florida Shore and Beach Preservation Association and Coastal and Oceanographic Engineering Department, University of Florida. Chasten, M. A., J. W. McCormick, and J. D. Rosati. 1994. Using detached breakwaters for shoreline and wetlands stabilization. Shore and Beach 62(2):17-22. Coastal Planning and Engineering. 1992a. General Design Memorandum Addendum for Third Peri- odic Nourishment at Delray Beach with Environmental Assessment. Boca Raton, Fla.: Coastal Planning and Engineering. Coastal Planning and Engineering. 1992b. Boca Raton Beach Restoration Project: Three Year Post- Construction, Vol. I. Environmental monitoring report prepared for the City of Boca Raton, Florida. Boca Raton, Fla.: Coastal Planning and Engineering. Cohrssen, J. J., and V. T. Covello. 1989. Risk Analysis: A Guide to Principles and Methods for Analyzing Health and Environmental Risks. Washington, D.C.: U.S. Council on Environmen- tal Quality. Combe, A. J., III, 1993. Grand Isle, Louisiana, Hurricane Wave Damage Prevention and Beach

244 BEA CH NO URISHMENT AND PR O TECTI ON Erosion Control, Louisiana Shoreline Erosion: Emphasis on Grand Island. The Louisiana Governor's Office of Coastal Activities and the U.S. Minerals Management Service. Combe, A. J., and C. W. Soileau. 1987. Behavior of man-made beach and dune, Grand Isle, Louisi- ana. Pp. 1232-1242 in Proceedings of Coastal Sediments '87, Specialty Conference on Ad- vances in Understanding of Coastal Sediment Processes. New York: American Society of Civil Engineers. Dally, W. R., and J. Pope. 1986. Detached Breakwaters for Shore Protection. U.S. Army Coastal Engineering Research Center, Technical Report CERC-86-1. Vicksburg, Miss.: Coastal Engi- neering Research Center, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. Davis, R. A., Jr. 1991. Performance of a beach nourishment project based on detailed multi-year monitoring: Redington Shores, Florida. Pp. 2101-2115 in Coastal Sediments '91, Vol. 2. New York: American Society of Civil Engineers. Davison, A. T., R. J. Nicholls, and S. P. Leatherman. 1992. Beach nourishment as a coastal manage- ment tool: an annotated bibliography on developments associated with the artificial nourish- ment of beaches. Journal of Coastal Research 8(4):984-1022. Dean, R. G. 1974. Compatibility of borrow material for beach fills. Pp. 1319-1333 in Proceedings of the 14th Coastal Engineering Conference, New York: American Society of Civil Engineers. Dean, R. G. 1983. Principles of beach nourishment. Pp. 217-232 in CRC Handbook of Coastal Processes and Erosion. Boca Raton, Fla..: CRC Press. Dean, R. G. 1987. Coastal sediment processes: toward engineering solutions. Pp. 1-24 in Proceed- ings of Coastal Sediments '87, Specialty Conference on Advances in Understanding of Coastal Sediment Processes, Vol. 1. New York: American Society of Civil Engineers. Dean, R. G. 1989. Pp. 313-336 in Measuring Longshore Transport with Traps in Nearshore Sediment Transport. R.J. Seymour, ea., New York: Plenum Press. Dean, R. G. 1991. Equilibrium beach profiles: characteristics and applications. Journal of Coastal Research 7(1):53-84. Dean, R. G., and J. Grant. 1989. Development of Methodology for Thirty-Year Shoreline Projection in the Vicinity of Beach Nourishment Projects. Prepared for Division of Beaches and Shore, Florida Department of Natural Resources, by the Florida Coastal and Oceanographic Engineer- ing Department, University of Florida, Gainesville. Dean, R. G., and C-H. Yoo. 1992. Beach nourishment performance predictions. Journal of Water- way, Port, Coastal and Ocean Engineering 118(6):567-586. del Valle, R., R. Medina, and M. A. Losada. 1993. Dependence of coefficient K on grain size. Technical Note, Journal of Waterway, Port, Coastal and Ocean Engineering 119(5):567-574. Dette, H., A. Fuhrboter, and A. J. Raudkiv. 1994. Interdependence of beach fill volumes and repeti- tion intervals. Journal of Waterway, Port, Coastal and Ocean Engineering 120(6):580-593. Dixon, K. L., and O. H. Pilkey. 1989. Beach replenishment on the U.S. coast of the Gulf of Mexico. Pp. 2007-2020 in Proceedings of Coastal Zone '89 Conference. New York: American Society of Civil Engineers. Dixon, K.L.. and O. H. Pilkey. 1991. Summary of beach replenishment on the U.S. Gulf of Mexico shoreline. Journal of Coastal Research 7:249-256. Dornhelm, R. B. 1995. The Coney Island public beach and boardwalk improvement of 1923. Shore and Beach 63(1):7-11. Edelman, T. 1972. Dune erosion during storm conditions. Pp. 1305-1311 in Proceedings of the 13th Coastal Engineering Conference. New York: American Society of Civil Engineers. Egense, A. K., and C. J. Sonu. 1987. Assessment of Beach Nourishment Methodologies. Pp. 4421- 4433 in Coastal Zone '87. New York: American Society of Civil Engineers. Farley, P. P. 1923. Coney Island public beach and boardwalk improvements. Paper 136. The Munici- pal Engineers Journal 9(4). Ferrante, A., L. Franco, and S. Boer 1992. Modelling and monitoring of a perched beach at Lido di

APPENDIX D 245 Ostia (Rome). Pp. 3305-3318 in Proceedings of the 23rd International Coastal Engineering Conference, Vol. 3. New York: American Society of Civil Engineers. Fiering, M. B., and B. B. Jackson. 1971. Synthetic Streamflows. Water Resources Monograph 1. Washington, D.C.: American Geophysical Union. Galster, R. W.? and M. L. Schwartz. 1990. Ediz Hook a case history of coastal erosion and rehabili- tation. Artificial Beaches, Special Issue, Journal of Coastal Research 6:103-113. Gordon, A. D. 1992. The restoration of Bate Bay, Australia-plugging the sink. Pp. 3319-3330 in Proceedings of the 23rd International Coastal Engineering Conference, Vol. 3. New York: American Society of Civil Engineers. Gordon, A. D. 1994. Letter to R. L. Wiegel dated 28 March 1994, 11 pp. Hall, J. V., Jr., 1952. Artificially constructed and nourished beaches in coastal engineering. Pp. 119- 133 in Proceedings of the 3rd Coastal Engineering Conference. New York: American Society of Civil Engineers. Hallermeier, R. J. 1981a. A profile donation for seasonal sand beaches from wave climate. Coastal Engineering 4:253-277. Hallermeier, R. J. 1981b. Seaward Limit of Significant Sand Transport by Waves: An Annual Zona- tion for Seasonal Profiles. Coastal Engineering Technical Aid No. CETA 81-2. Fort Belvoir, Va..: Coastal Engineering Research Center, U.S. Army Corps of Engineers. Hands, E. B. 1991. Unprecedented migration of a submerged mound off the Alabama coast. In: Proceedings of the 12th Annual Conference of the Western Dredging Association and 24th Annual Texas A & M Dredging Seminar, Las Vegas. Hands, E. B., and M. C. Allison. 1991. Mound migration in deeper water and methods of categoriz- ing active and stable berms. Pp. 1985-1999 in Proceedings of Coastal Sediments '91. New York: American Society of Civil Engineers. Hanson, M. E., and M. R. Byrnes. 1991. Development of optimum beach fill design cross-section. Pp. 2067-2080 in Proceedings of Coastal Sediments '91, New York: American Society of Civil . engineers. Hanson, H., and N. C. Kraus. 1989. GENESIS: Generalized Model for Simulating Shoreline Change. Report 1: Reference Manual and Users Guide. Technical Report No. CERC-89-19. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. Hanson, H., and N. C. Kraus. 1991. Numerical simulation of shoreline change at Lorain, Ohio. Journal of Waterway, Port, Coastal and Ocean Engineering 117:1-18. Hanson, M. E., and W. J. Lillycrop. 1988. Evaluation of closure depth and its role in estimating beach fill volumes. Pp. 107-114 in Proceedings of Beach Preservation Technology '88. Talla- hassee: Florida Shore and Beach Preservation Association. Healy, T., C. Harms, and W. de Lange. 1991. Dredge spoil and inner shelf investigations off Tauranga Harbour, Bay of Plenty, New Zealand. Pp. 2037-2051 in Proceedings of Coastal Sediment '91. New York: American Society of Civil Engineers. Herron, W. J., and R. L. Harris. 1966. Littoral bypassing and beach restoration in the vicinity of Port Hueneme, California. Pp. 651-675 in Proceedings of the 10th Conference on Coastal Engineer- ing. Vol 1. New York: American Society of Civil Engineers. Hirst, E. H. W., and D. Foster. 1987. The design and construction of Prince Street seawall at Cronulla. Pp. 201-207 in Proceedings of the 8th Australian Conference on Coastal and Ocean Engineer- ing. Launceston, Australia: Institution of Civil Engineers. Houston, J. R. 1991a. Beachfill performance. Shore and Beach 59:15-24. Houston, J. R. l991b. Rejoinder to: Discussion of Pilkey and Leonard (1990) [Journal of Coastal Research, 6, 1023 et. seq.] and Houston (1990) [Journal of Coastal Research, 6, 1047 et. seq.]. Journal of Coastal Research 7:565-577. James, W. R. 1974. Beach fill stability and borrow material texture. Pp. 1334-1349 in Proceedings of

246 BEACH NOURISHMENT AND PROTECTION the 14th International Conference on Coastal Engineering. New York: American Society of Civil Engineers. James, W. R. 1975. Techniques in Evaluating Suitability of Borrow Material for Beach Nourish- ment. Technical Manual No. 60. Ft. Belvoir, Va.: Coastal Engineering Research Center, U.S. Army Corps of Engineers. Jarrett, J. T., 1987. Beach Nourishment A Corps Perspective. Paper presented at the Coastal Engi- neering Research Board's 48th Meeting, Savannah, Georgia. Vicksburg, Miss.: Coastal Engi- neering Research Board, U.S. Army Corps of Engineers. Jensen, R. E. 1983. Atlantic Coast Hindcast, Shallow Water Significant Wave Information. Wave Information Study Report No. 9. Vicksburg, Miss.: U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. Kamphuis, J. W., 1990. Littoral sediment transport rate. Pp. 2402-2415 in Proceedings of 22nd Coastal Engineering Conference. New York: American Society of Civil Engineers. Kamphuis, J. W. 1991. Alongshore sediment transport rate. Journal of Waterways, Port, Coastal and Ocean Engineering 117(6):624-640. Kamphuis, J. W., M. H. Davies, R. B. Nairn, and O. J. Sayao. 1986. Calculation of littoral sand transport rate. Coastal Engineering 10: 1 -21. Kieslich, J. M., and D. H. Brunt III. 1989. Assessment of a two-layer beach fill at Corpus Christi Beach, Texas. Pp. 3975-3984 in Proceedings of the 6th Symposium on Coastal and Ocean Management, Coastal Zone '89. New York: American Society of Civil Engineers. Komar, P. D. 1973. Computer models of delta growth due to sediment input from rivers and longshore transport. Geological Society of America Bulletin 84:2217-2226. Komar, P. D. 1976. Beach Processes and Sedimentation. Englewood Cliffs, N.J.: Prentice-Hall. Komar, P. D. 1977. Modeling of sand transport on beaches and the resulting shoreline evolution. Pp. 499-513 in E. Goldberg et al., eds., The Sea, Vo1. 6. Komar, P. D., 1988. Environmental controls on littoral sand transport. Pp. 1238-1252 in Proceedings of 21st Coastal Engineering Conference, Vol. 2. New York: American Society of Civil Engi neers. Kraus, N. C., H. Hanson, and S. Blomgren. 1994. Modern functional design of groins. In: Proceed- ings of the 24th Coastal Engineering Conference. New York: American Society of Civil Engi neers. Kriebel, D. 1982. Beach and Dune Response to Hurricanes. M.S. thesis, University of Delaware, Newark. Kriebel, D. L. 1986. Verification study of a dune erosion model. Shore and Beach 54(3). Kriebel, D. L. 1990. Advances in numerical modeling of dune erosion. Pp. 2304-2317 in Proceed- ings, 23rd International Conference on Coastal Engineering. Kriebel, D. L., and R. G. Dean. 1985. Numerical simulation of time dependent beach and dune erosion. Coastal Engineering 9:221-245. Kriebel, D. L., and R. G. Dean. 1993. Convolution method for time-dependent beach profile re- sponse. Journal of Waterways, Port, Coastal and Ocean Engineering 119(2):204-227. Kriebel, D. L., N. C. Kraus, and M. Larson. 1991. Engineering methods for predicting beach profile response. Pp. 557-571 in Proceedings of Coastal Sediments '91. New York: American Society of Civil Engineers. Krumbein, W. C. 1957. A Method for Specification of Sand for Beach Fills. Technical Memorandum No. 102. Washington, D.C.: Beach Erosion Board, U.S. Army Corps of Engineers. Krumbein, W. C., and W. R. James. 1965. A Lognormal Size Distribution Model for Estimating Stability of Beach Fill Material. Technical Memorandum No. 16. Washington, D.C.: Coastal Engineering Research Center, U.S. Army Corps of Engineers. Larson, M. 1988. Quantification of Beach Profile Change. Report No. 1008. Department of Water Resources and Engineering, University of Lund, Lund, Sweden. Larson, M., and N. C. Kraus. 1989a. Prediction of beach fill response to varying waves and water

APPENDIX D 247 level. Pp. 607-621 in Proceedings of Coastal Zone '89. New York: American Society of Civil Engineers. Larson, M., and N. C. Kraus. 1989b. SBEACH: Numerical Model for Simulating Storm-Induced Beach Change. Report 1: Empirical Foundation and Model Development. Technical Report No. CERC-89-9. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Water- ways Experiment Station, U.S. Army Corps of Engineers. Larson, M., and N. C. Kraus. 1990. SBEACH: Numerical Model for Simulating Storm-Induced Beach Change. Report 2: Numerical Foundation and Model Tests. Technical Report CERC-89- 9. Vicksburg, Mississippi: Coastal Engineering Research Center, U.S. Army Waterways Ex- periment Station, U.S. Army Corps of Engineers. Larson, M., and N. C. Kraus. 1991. Mathematical modeling of the fate of beach fill. Coastal Engi- neering 16:83-114. Larson, M., and N. C. Kraus. 1994. Temporal and spatial scales of beach profile change, Duck, North Carolina. Marine Geology 117 :75 -94. Lee, G-H.. and W. A. Birkemeier. 1993. Beach and nearshore survey data: 1985-1991 CERC field research facility. Technical Report CERC-93-3. Vicksburg, Miss.: Coastal Engineering Re- search Center, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. Leonard, L. A. 1988. An Analysis of Replenished Beach Design on the U.S. East Coast. Unpublished M.S. thesis, Department of Geology, Duke University, Durham, N.C. Leonard, L. A., T. D. Clayton, K. L. Dixon, and O. H. Pilkey. 1989. U.S. Beach replenishment experience: a comparison of beach replenishment on the U.S. Atlantic, Pacific, and Gulf of Mexico coasts. Pp. 1994-2006 in Proceedings of Coastal Zone '89. New York: American Society of Civil Engineers. Leonard, L. A., K. L. Dixon, and O. H. Pilkey. 1990a. A comparison of beach replenishment on the U.S. Atlantic, Pacific, and Gulf coasts. Journal of Coastal Research, 6(Special Issue):127-140. Leonard, L. A., T. D. Clayton, and O. H. Pilkey, l990b. An analysis of replenished beach design parameters on U.S. East Coast Barrier Islands. Journal of Coastal Research 6(Special Issue):15- 36. Louisse, C. J., and F. van der Meulen. 1991. Future coastal defense in the Netherlands: strategies for protection and sustainable development. Journal of Coastal Research 7:1027-1041. McLellan, T. N. 1990. Nearshore mound construction using dredged material. Journal of Coastal Research 7(Special Issue):99-107. McLellan, T. N., and N. C. Kraus. 1991. Design guidance for nearshore berm construction. Pp. 2000- 2011 in Proceedings of Coastal Sediments '91. New York: American Society of Civil Engi- neers. Mikkelsin, S. C. 1977. The effects of groins on beach erosion and channel stability at the Limfjord Barriers, Denmark. Pp. 17-32 in Proceedings of Coastal Sediments '77. New York: American Society of Civil Engineers. Nersesian, G. K., N. C. Kraus, and F. C. Carson. 1992. Functioning of groins at Westhampton Beach, Long Island, New York. Pp. 3357-3370 in Proceedings of the 23rd International Coastal Engi- neering Conference, Vol. 3. New York: American Society of Civil Engineers. NRC. 1987. Responding to Changes in Sea Level: Engineering Implications. Marine Board, Com- mission on Engineering and Technical Systems. Washington, D.C.: National Academy Press. NRC. 1989. Measuring and Understanding Coastal Processes for Engineering Purposes. Marine Board, Commission on Engineering and Technical Systems. Washington, D.C.: National Acad- emy Press. NRC. 1990. Managing Coastal Erosion. Water Science and Technology Board and Marine Board, Commission on Engineering and Technical Systems. Washington, D.C.: National Academy Press. NRC. 1992. Coastal Meteorology: A Review of the State of the Science. Board on Atmospheric

248 BEACH NOURISHMENT AND PROTECTION Sciences and Climate, Commission on Geosciences, Environment, and Resources. Washing- ton, D.C.: National Academy Press. O'Brien, M. P., 1988. Letter to Professor Ben C. Gerwick, Jr., University of California, Berkeley (4 pp. plus four aerial photos concerning how a groin field functions, making the need for a sand fill part of the project). Pelnard-Considere, R. 1956. Essai de Theorie de l,Evolution des Formes de Rivate en Plages de Sable et de Galets. 4th Journees de l'Hydraulique, Les Energies de la Mar, Question III, Rap- port No. 1 (in French). Vicksburg, Miss.: U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. Perlin, M., and R. G. Dean.1979. Prediction of beach planforms with littoral controls. Pp. 1818-1838 in Proceedings of the 16th Coastal Engineering Conference. New York: American Society of Civil Engineers. Pilkey, O. H., and T. D. Clayton. 1987. Beach replenishment: the national solution? Pp. 1408-1419 in Proceedings of Coastal Zone '87. New York: American Society of Civil Engineers. Pilkey, O. H., and T. D. Clayton. 1988. Summary of beach replenishment experience on the U.S. coast barrier islands. Journal of Coastal Research 5:147-159. Pope, J., and D. D. Rowen. 1983. Breakwaters for beach protection at Lorain, Ohio. Pp. 752-768 in Proceedings of Coastal Structures '83. New York: American Society of Civil Engineers. Price, R. C. 1966. Statement of the California Department of Water Resources. Shore and Beach 34(1):22-32. Price, W. A., K. W. Tomlinson, and D. H. Willis. 1973. Predicting changes in the plan shape <'f beaches. Pp. 1321-1329 in Proceedings of the 13th Conference on Coastal Engineering. New York: American Society of Civil Engineers. Richardson, T. W. 1991. Sand bypassing. Pp. 809-828 in J. B. Herbich, (ed). Handbook of Coastal and Ocean Engineering, Vol. 2. Houston: Gulf Publishing Co. Rosati, J. D. 1990. Functional Design of Breakwaters for Shore Protection; Empirical Methods. Technical Report CERC-90-15. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Waterway Experiment Station, U.S. Army Corps of Engineers. Rouch, F., and B. Bellessort. 1990. Man-made beaches more than 20 years on. Pp. 2394-2401 in Proceedings of the 22nd Coastal Engineering Conference, Vol. 3. New York: American Soci- ety of Civil Engineers. Shih, S. M., and P. D. Komar. 1994. Sediments, beach morphology and sea cliff erosion within an Oregon coast littoral cell. Journal of Coastal Research 10:144-157. Silvester, R., and J. R. C. Hsu. 1993. Coastal Stabilization: Innovative Concepts. Englewood Cliffs, N.J.: Prentice-Hall. Strine, M. A., Jr., and R. A. Dalrymple. 1991. A Probabilistic Prediction of Beach Nourishment Lifetimes. Research Report No. CACR-91-01. Newark: Center for Applied Coastal Research, Department of Civil Engineering, University of Delaware. Strock, A. V., and Associates. 1981. Phase I General Design Memorandum, Segment II of Broward County, Hillsboro Inlet to Port Everglades, Beach Erosion Control and Storm Protection Study, November. Strock, A. V., and Associates. 1984. General Design Memorandum, Second Periodic Nourishment Project. Delray Beach, Florida, January. Swart, D. H. 1974. Offshore Sediment Transport and Equilibrium Beach Profiles. Publication No. 131. Delft, The Netherlands: Delft Hydraulics Laboratory. Terry, J. B.* and E. Howard. 1986. Redington shores beach access breakwater. Shore and Beach 54(4):7-9. Tomasicchio, U. 1994. Personal communication with R. L. Wiegel. Tourman, L. 1968. The creation of an artificial beach in Larvatto Bay-Monte Carlo, principality of Monaco. Pp. 558-569 in Proceedings of 11th Conference on Coastal Engineering. New York: American Society of Civil Engineers.

APPENDIX D 249 USACE. 1957. Beach Erosion Control Report on Cooperative Study of Key West, Florida. Jackson- ville, Fla.: Jacksonville District, U.S. Army Corps of Engineers. USACE. 1982a. Beach Fill Transitions. Coastal Engineering Technical Note CETN-II-6. Fort Belvoir, Va.: Coastal Engineering Research Center, U.S. Army Corps of Engineers. USACE. 1982b. Feasibility Report and Environmental Assessment on Shore and Hurricane Wave Protection, Wrightsville Beach, N. C.: Wilmington, North Carolina: Wilmington District, U.S. Army Corps of Engineers. USACE. 1982c. Final Feasibility Report and Environmental Impact Statement for Beach Erosion Control, Monroe County, Florida. Jacksonville, Fla.: Jacksonville District, U.S. Army Corps of Engineers. USACE. 1984. Shore Protection Manual, 4th ed. two volumes. Coastal Engineering Research Cen- ter, U.S. Army Corps of Engineers Publication No. 008-002-00218-9. Washington, D.C.: U.S. Government Printing Office. USACE. 1985. Sediment Size and Fall Velocity Effects on Longshore Sediment Transport. Coastal Engineering Technical Note CETN-II-11. Vicksburg, Miss.: Coastal Engineering Research Cen- ter, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. USACE. 1986. Storm Surge Analysis. Engineer Manual No. EM 1110-2-1412. U.S. Army Corps of Engineers. Washington, D.C.: U.S. Government Printing Office. USACE. 1988. Coastal Processes at Sea Bright to Ocean Township, New Jersey. Miscellaneous Paper CERC-88-12. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Wa- terways Experiment Station, U.S. Army Corps of Engineers. USACE. 1989a. Water Level and Wave Heights for Coastal Engineering Design. Engineering Manual 1110-2-1414. Washington, D.C.: U.S. Government Printing Office. USACE. 1989b. Wrightsville Beach, North Carolina, Renourishment Report and Supplement to the Environmental Assessment and Finding of No Significant Impact. Wilmington, N.C.: Wilmington District, U.S. Army Corps of Engineers. USACE. 1990. Comparison of Atlantic Coast Wave Information Study Hindcasts with Field Re- search Facility Gauge Measurements. Technical Report CERC-90-17, Final Report. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. USACE. 1991a. Sand Bypassing System, Engineering and Design Manual. Engineering and Design Manual No. EM 1110-2-1616. Washington, D.C.: U.S. Army Corps of Engineers. USACE. l991b. National Economic Development Procedures Manual Coastal Storm Damage and Erosion. Institute of Water Resources Report No. 91-R-6. Fort Belvoir, Va.: Institute for Water Resources, Water Resources Support Center, U.S. Army Corps of Engineers. USACE. l991c. Manatee County, Florida, Shore Protection Project, General Design Memorandum, with Environmental Impact Statement. Revised September 1991. Jacksonville, Fla.: Jackson- ville District, U.S. Army Corps of Engineers. USACE. 1992a. Shoreline Response to Redington Shores, Florida, Breakwater. Coastal Engineering Technical Note CETB III-48. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Waterways Experiment Station, U.S. Army Corps of Engineers. USACE. 1992b. Monitoring Coastal Projects. Engineer Regulation ER 1110-2-8151. Washington, D.C.: U.S. Army Corps of Engineers. USACE. 1993. Reliability Assessment of Existing Levees for Benefit Determination, Engineering and Design, Engineer Technical Letter 1110-2-328. Washington, D.C.: U.S. Army Corps of ~ . engineers. University of Florida. 1959. Bakers Haulover Inlet Tidal Model Study on Beach Erosion and Navi- gation, Industrial Experiment Station. Vallianos, L. 1974. Beach fill planning Brunswick County. North Carolina. Pp. 1350-1369 in Proceedings of 14th Coastal Engineering Conference. New York: American Society of Civil ~ . engineers.

250 BEACH NOURISHMENT AND PROTECTION Vera-Cruz, D. 1972. Artificial nourishment of Copacabana Beach. Pp. 1451-1463 in Proceedings of the 13th Coastal Engineering Conference. New York: American Society of Civil Engineers. Verhagen, H. J. 1990. Coastal protection and dune management in the Netherlands. Journal of Coastal Research 6: 169-179. von Oesen, H. M. 1973. A beach restoration project: Bal Harbour Village, Florida. Shore and Beach 41(2):3-4. Walker, J. R., D. Clark, and J. Pope 1980. A detached breakwater system for beach protection. Pp. 1968-1987 in Proceedings of 17th Coastal Engineering Conference, Vol. II. New York: Ameri- can Society of Civil Engineers. Walton, T. L. 1985. Sediment Size and Fall Velocity Effects on Lon,shore Sediment Transport. CETN II-11. Vicksburg, Miss.: Coastal Engineering Research Center, U.S. Army Engineer Waterways Experiment Station, U.S. Army Corps of Engineers. Watson, I., and C. W. Finkl. 1990. State of the art in storm surge protection: The Netherlands delta project. Journal of Coastal Research 6:739-764. Weggel, J. R., and R. M. Sorensen. 1991. Performance of the 1986 Atlantic City, New Jersey, beach nourishment project. Shore and Beach 59(3):29-36. Weggel, J. R., S. L. Douglass, and J. E. Tunnell. 1988. Sand-bypassing simulation using synthetic longshore transport data. Journal of Waterway, Port, Coastal, and Ocean Engineering 114(2): 146-160. Wiegel, R. L. 1987. Trends in coastal erosion management. Shore and Beach 55(1):3-11. Wiegel, R. L. 1988. Keynote address: some notes on beach nourishment, problems and advancement in beach nourishment. Pp. 1-18 in Proceedings of Beach Preservation Technology '88. Talla- hassee: Florida Shore and Beach Preservation Association. Wiegel, R. L. 1991. The coast-line, III, protection of Galveston, Texas, from overflow by gulf storms: grade-raising, seawall and embankment, American Shore and Beach Preservation As- sociation Coastal Project Award for 1990. Shore and Beach 59(1):4-10. Wiegel, R. L. 1992. Dade County, Florida, beach nourishment and hurricane surge protection. Shore and Beach 60(4):2-28. Wiegel, R. L. 1993. Dana Point Harbor, California. Shore and Beach 61(3):37-55. Williams, S. J., and E. P. Meisburger. 1987. Sand sources for the transgressive barrier coast of Long Island, N.Y.: evidence for landward transport of shelf sediments. Pp. 1517-1532 in N. C. Kraus, ea., Proceedings of Coastal Sediments '87. New York: American Society of Civil Engi neers. Wise, R. A., and N. C. Kraus. 1993. Simulation of beach fill response to multiple storms, Ocean City, Maryland. Pp. 133-147 in Proceedings of Coastal Zone '93. New York: American Soci- ety of Civil Engineers. Zwamborn, J. A., G. A. W. Fromme, and J. B. Fitzpatrick. 1970. Underwater mound for protection of Durban's beaches. Pp. 975-994 in Proceedings of the 12th Coastal Engineering Conference. New York: American Society of Civil Engineers.