ESDODDS: EXPERIMENTS ON SEDIMENT DEPTH OF DISTURBANCE FOR BEACHES UNDER THE INFLUENCE OF DRAINAGE SYSTEMS

The paper describes experiments undertaken the Large Wave Channel (Grosser Wellen Kanal, GWK) in Hannover on sediment mixing on a beachface exposed to the action of a buried drainage system. The general aim of the project was to understand the role of swash infiltration processes inside the sediment column. Preliminary results indicate that under High Energy wave conditions (Hs=0.8 m, Tp=6.5 s) the beach reached a quasi-equilibrium profile shape after 120 minutes of wave attacks. Thereafter the action of two adjacent drains did not stop shoreface erosion, except for the area immediately over the drains. Sediment mixing was small (approx 2-4% of wave height) and seemed to increase under drained conditions.