Morphodynamics and sand bypassing at Ameland Inlet, The Netherlands

In this paper, we review and analyze the cyclic morphodynamics and sand-bypassing processes at the Ameland Inlet, The Netherlands. The inlet is located between the islands of Terschelling and Ameland in the Dutch Wadden Sea. The bypassing rate and sand storage have a periodicity of 50 to 60 years in connection with the migration of the channels in the inlet and the transformation of the gorge between a one-channel and a two-channel system. These developments modulate the volumes of the shoal and bypassing bars and produce an attenuating sand wave toward the downdrift coast. An aggregate model is developed to describe the inlet morphology at this intermediate timescale. The model is based on a modified equilibrium-volume approach, which allows erosion and accretion of the shoal and bars to occur about their long-term equilibrium. The model results depict observed morphologic behaviors of the inlet and corroborate the measured modulation of the downdrift coastline. The simulation of the effect of the 1979 and 1980 sand mining operations in the ebb tidal delta reproduces the reported rapid recovery of the sandpits and illustrates the capabilities of the model as an inlet planning and management tool.