The Effect of a Groin Field on a Sandy Beach

A model has been developed that explains sediment accumulation within a groin field from the aspect of mass conservation. The model revealed that intergroin sedimentation is related to the gradient of the adjacent longshore sediment transport. An important model parameter is the length Lambda of the structure's zone of influence. It is shown that the accumulation rate reaches its maximum when the intergroin distance is close to 2 Lambda, while material accretion terminates when the distance is close to 2 Lambda. The optimal relationships between the intergroin distance, groin length, and width of the sediment flux have been obtained. This allows operational forecasting of the accumulation volume and distance the beach advances within time periods from hours to decades. The model can calculating the optimal groin field parameters to achieve the required performance and avoid unnecessary impacts. The calculations reasonably agreement with published observations.