Shoreline Response to Coastal Structures

Abstract

The coastal erosion has become a critical problem for states which are facing acute shortage of land due to high density of population and narrow width available for the state. With this in mind, different protection methods have been used over time, most on the basis of the artificial nourishment of beaches and building coastal structures such as groins and detached breakwaters. The decision to build a coastal structure should be based on a thorough analysis of the shoreline developments in the past and estimated developments in the future. The physical processes causing erosion should be properly identified, otherwise erroneous decisions may be taken. In the present paper an attempt is made to design series of groins and series of detached breakwaters for shore protection taking into account both alongshore sediment transport and cross-shore sediment transport. A mathematical model was used, which takes into account wave parameters, detached breakwater configuration, groins configurations, initial shoreline and bathymetry as input and provides shoreline changes. Shoreline response was obtained by varying various parameters of detached breakwaters and groins, such as detached distance of breakwaters, gap width between the breakwaters, width of breakwater, length of groins, gap width between groins and length of groins. With detached breakwaters it was seen that coastline is subjected to less erosion as compared to the groins because detached breakwater does not block the littoral drift completely and allows passage of some drift material. Therefore detached breakwaters used in combination with beach nourishment offer a better and environmentally suitable solution to combat coastal erosion problems.