Study Site Characterization

Abstract

a. Many coastal failures can be traced back to inadequate site characterization analyses. Site characterization involves identifying distinguishing qualities and features of a region that have a direct and indirect impact on the conception, design, economics, aesthetics, construction, and maintenance of a coastal project. The coastal environment varies spatially and temporally and therefore a design that is functionally, economically, and environmentally appropriate at one location may be inappropriate at another. Physical, biological, and cultural attributes need to be delineated so that an acceptable project is adopted and potential effects of the project are determined. b. Waves bring an enormous amount of energy to the coast that is dissipated through wave breaking, generation of currents, water level changes, movement of sediment, turbulence, and heat. Incident waves vary spatially and temporally, with their properties changing with movement over the bottom. The beach is composed of sediment particles of various types, sizes, and shapes which move along and across the shore. The beach and backshore exhibit different textural properties that vary alongshore, across-shore, and with time. The coastal region supports a diverse biological community of aquatic, terrestrial, and avian organisms. It also must continue to enhance the quality of human existence by providing commercial and recreational benefits. In light of the profound diversity of the coastal zone, it is imperative that the coastal designer have a full understanding of potential impacts of engineering activities on the regional environment. c. This chapter enumerates important physical and engineering factors that should be identified. Readers are directed to other pertinent sections of this manual for specific details on monitoring the coastal environment and for information on the physics of coastal processes. Not all factors described in this chapter pertain to all coasts. For example, ice and volcanic hazards are not applicable to a Gulf Coast project design. However, most factors should be included in all other site characterizations. d. General Design Memorandums (GDMs) and monitoring reports (Table V-2-1) prepared by U.S. Army Corps of Engineer (USACE) Districts may be consulted for examples of site characterization studies. The Alaska Coastal Design Manual (U.S. Army Corps of Engineers 1994) also summarizes important site characterization features