ANALYTICAL SOLUTIONS OF ONE-LINE MODEL FOR SHORELINE CHANGE NEAR COASTAL STRUCTURES

Analytical solutions provide a simple and economical means of quickly estimating qualitative and quantitative responses of the shoreline to a wide range of environmental and engineering conditions. This paper p resents analytical solutions for shoreline evolution in the vicinity o f coastal structures, including detached breakwaters, seawalls, and je tties with and without wave diffraction. The solution for a detached b reakwater illustrates the growth of a salient with time behind the bre akwater and the associated initial shoreline retreat at locations acro ss from the breakwater tips. A simple solution describing flanking of a seawall is obtained by using two different solution areas where the longshore sand transport rate and breaking-wave angle vary. A similar technique is used to model diffraction downdrift of a groin or jetty b y allowing the wave angle to vary with the distance alongshore accordi ng to a specified function or by employing a large number of solution areas. Cases are also presented for the accumulation updrift a groin a nd the shoreline response in a groin compartment with a breaking wave angle that varies sinusoidally in time. A solution for a single groin illustrates the impact of bypassing on the updrift accumulation.