systematic manner (as given here and in the GENESIS Workbook) . Most physical 

 data needed for evaluating and interpreting shoreline and beach evolution 

 processes in a broad sense are used in the shoreline change modeling metho- 

 dology. Certain other data may be lacking in particular applications having 

 unique requirements , so that coastal experience and overall project planning 

 should not be subverted by complete dependence on shoreline change modeling 

 requirements . 



47. Geological and regional factors such as earthquakes, subsidence, 

 and structure of the sea bottom substrata may indirectly enter into shoreline 

 change modeling. For example, interpretation of historic shoreline position 

 change must account for subsidence if it has occurred. Environmental factors 

 such as water circulation and quality (temperature, salinity, sediment 

 concentration, etc.), as well as biological factors, may also have to be 

 considered. For example, although GENESIS can model the movement of beach- 

 fill material placed at arbitrary locations and times along the beach, the 

 breeding habits of sea turtles and birds may restrict the season and/or 

 location of the fill and constrain the project design and construction 

 schedule. In summary, satisfaction of the data requirements of the shoreline 

 change model provides an organized and comprehensive first step in assembling 

 the necessary data for project design. 



Steps c-e 



48. Provided that shoreline change at the site can be modeled, GENESIS 

 is well suited for quantitative and systematic evaluation of alternatives and 

 for optimization of the final plan. As an example, Hanson and Kraus (1986a) 

 simulated beach change for nine hypothetical combinations of plans to mitigate 

 erosion at a recreational beach. The without-project ("do nothing") alterna- 

 tive and several shore -protection schemes were evaluated for groins of various 

 sizes and spacings , beach fills of various quantities, and a single, long 

 detached breakwater. Technical criteria for judging the solution involved two 

 factors, protection of the eroding beach and minimization of the quantity of 

 sand transported downcoast that would enter the navigation channel of a 

 fishing harbor. For each alternative, shoreline change modeling allowed 



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