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Beach Nourishment and Protection (1995) / Chapter Skim
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7 Conclusions and Recommendations
Pages 140-158

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From page 140...
... RECOMMENDATION: Federal, state, and local authorities with responsibility for coastal protection should view beach nourishment as a viable alternative for providing shore protection and for restoring lost recreational beach assets. The planning and execution of successful beach nourishment projects can best be accomplished through a broadly based coalition of disciplines and interests that brings together all the scientific, engineering, economic, and governance knowledge and experience available.
From page 141...
... establish the goals and expectations of the project and its continuation as a long-term program; establish clear and quantifiable measures of success; establish and maintain an effective monitoring program that supports the management, design, and execution of subsequent nourishment cycles; develop and maintain a public awareness program; and account for the uncertainties implicit in shore protection measures through the implementation of contingency planning and the identification of future sources of both renourishment material and project funding. SPECIFIC FINDINGS Design The design of a successful beach nourishment project depends on an understanding of the underlying causes of erosion at the site and a capacity to model or evaluate quantitatively the coastal processes, such as wave climate variations and the cross-shore and alongshore transport rates of sediments.
From page 142...
... RECOMMENDATION: The design methodology for beach nourishment projects should include the following: · design profiles based on natural profiles at the site suitably adjusted for nourishment grain size rather than straight line segments or other unrealistic approximations; spreading losses owing to the nourishment project accounted for explicitly in the design; volumes adjusted to account for rock outcrops and seawalls in order to provide sufficient volume to nourish the entire profile from the berm or dune to the seaward limit of the active profile and avoid underestimating fill requirements; sediment performance characteristics included in the analysis of sediment considered for use as beach nourishment material, with specific attention to the equilibrium shape of the profile, the transportability of the sediment alongshore, and the erodibility of the material during a storm; these factors used at first in conjunction with overfill and renourishment factors and later as a substitute for these factors as more experience is gained; the possibility of erosional hot spots recognized in the design; analytical and numerical models used to estimate end losses that will be caused by spreading of the fill material to adjacent . beaches; the Blrst renourishment time interval shortened to allow for uncertainties in alongshore erosion rates, thus enabling correction of erosional hot spots before the design is compromised and avoiding overbuilding of accretional areas; and safety factors developed to account for variability and uncertainty and applied appropriately to both design volumes and advanced-fill volumes.
From page 143...
... , to provide a reserve capability to prevent flooding and wave attack where dunes cannot or do not exist, especially in areas like the Pacific coast, where storm surges are small and to reduce wind-blown losses to the land. Broad prohibitions on the use of fixed structures in conjunction with beach nourishment projects can contribute to suboptimal project performance where fixed structures can provide secondary storm damage reduction or are needed to anchor the ends of projects.
From page 144...
... If a beach nourishment project is not maintained, adverse effects of any structure should be mitigated or the structure should be removed. Nontraditional Shore Protection Devices The techniques used in conventional shore protection have had the benefit of decades of field performance and the development of demonstrated design models to predict that performance.
From page 145...
... RECOMMENDATION: Sponsors of beach nourishment projects should use a methodology for selecting borrow sites that assesses: · the required quality and quantity of sand, · the effect of borrow sites on adjacent beaches when these sites are located within the closure depth of the beach profile or are part of a shoal that normally feeds the downdrift beach, and · the need for, and negative and positive effects of, bypassing sand. If sand must be taken from borrow sites located within closure depths, it should be done as a planned sand bypass operation that is designed specifically to mitigate the effects of a feature or structure that interrupts the littoral movement of sand.
From page 146...
... that will trigger renourishment; the timing and extent of the expected profile adjustment and its impact on . beach widths; the possible impacts of major storms on beach character and on projected costs, sand volumes, and the timing between renourishment projects; the potential occurrence of erosional hot spots and the requirements for corrective action; and the adjustment from the temporarily wider and steeper construction pro file to the expected equilibrium profile.
From page 147...
... Department of the Interior will become increasingly important for the continued maintenance of some beach nourishment programs. Existing mechanisms for allocating these mineral resources through competitive bidding, and by negotiated agreement between the USACE and the Minerals Management Service for projects involving federal cost sharing, do not incorporate provisions for contracting forward for sand resources.
From page 148...
... Project Scope Beach nourishment programs are often undertaken without due consideration for their relationship to and impact on other portions of the littoral cell that often cross political boundaries. Most programs encompass only a portion of an area that can be considered a littoral geographic region or littoral cell.
From page 149...
... Therefore, various measures of success need to be defined for beach nourishment programs. A program may or may not be successful in meeting all objectives underlying its establishment.
From page 150...
... Environmental and Monitoring Issues Most beach nourishment programs are inadequately monitored following construction. Monitoring of the physical environment and the performance of the fill material is often too limited in scope and duration to quantify project performance adequately.
From page 151...
... Costs and Benefits Assessing and Allocating Costs and Benefits Beach nourishment programs result in economic benefits in a variety of forms and to a variety of recipients. Cost-share ratios arbitrarily mandated by Congress do not necessarily reflect the actual distribution of benefits; nor do these ratios take into account the impact of navigation projects on nearby and downdrift shores.
From page 152...
... In particular, the policy should recognize the storm damage reduction and recreational values to the total area affected and account for the benefits of sand transport to adjacent areas. Because only limited postconstruction assessment of beach nourishment programs has taken place, there is little information about the types of costs and benefits (beyond storm damage reduction and recreation)
From page 153...
... RECOMMENDATION: The U.S. Army Corps of Engineers should improve the basis for economic valuation of beach nourishment projects by: · reassessing the categories of costs and benefits included in evaluating a project, · incorporating uncertainties in assessing uncertain costs and benefits both with and without the project, · investigating behavioral responses stimulated by beach nourishment projects; and their policy ramifications, and · coupling projects with local growth and land-use plans to increase the net benefits of projects and designing financing schemes that provide efficient incentives.
From page 154...
... Nevertheless, the increase in the level of protection provided by beach nourishment projects and programs supports a finding of reduction in flooding risk, which would merit a reduction in insurance premiums. RECOMMENDATION: The Federal Emergency Management Agency should weigh the effect of an adequately designed, constructed, and maintained beach nourishment program on flooding risk and hence on flood insurance premiums.
From page 155...
... Second, mitigation funds may be used to restore beach and dune dimensions as soon as possible to protect against subsequent storm damage. At present, these are the only standing emergency assistance programs available at the federal level for shore protection and are relied on by coastal communities following damaging storms.
From page 156...
... RECOMMENDATION: In recognition of uncertainties in the prediction of coastal processes, cognizant government authorities should establish and maintain construction and location requirements to set construction back from the storm hazard regardless of whether a beach nourishment project is in place. RECOMMENDATION: In recognition of uncertainties in the prediction of coastal processes, the Federal Emergency Management Agency should establish and maintain construction standards for buildings or lots within the benefit area of a beach nourishment program and should prepare Flood Insurance Rate maps as if a beach nourishment project were not in place.
From page 157...
... RECOMMENDATION: The U.S. Army Corps of Engineers should require the collection, analysis, and dissemination of directional wave data as part of major beach nourishment programs in which there is a federal cost share.


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