An Experimental Study of Beach Evolution with an Artificial Seepage

Abstract

Beach erosion caused by extreme wave events (storm surges) is reported to occur in many coastal areas. Artificially lowering the groundwater table effectively stabilizes sand beaches in an environmentally friendly way. Mechanisms affecting beach stabilization remain unclear, however, due to the complex interaction between waves and coastal seepage. This study discusses the effects of coastal seepage on beach profile evolution and bed materials sorting based on laboratory experiments in which seepage is induced artificially by a drain pipe at three cross-shore locations on a 1:10 beach. Morphodynamic beach responses with and without seepage under a typical cnoidal wave condition are reported. Results show that artificial seepage impacts only insignificantly on total upper-beach deposition volume but could increase accretion on the berm’s leeside by reducing seaside sand accumulation. It also induces a steeper berm slope and shoreline recession. A drain pipe near the shoreline generated the greatest accretion height on the upper beach. Seepage location had no significance effect on bed material sorting, however.