Coastal Protection against Wind-Wave Induced Erosion Using Soft and Porous Structures: A Case Study at Lake Biel, Switzerland

At the southern shore of Lake Biel in Mörigen, Switzerland, the sandy beach covered with reed plantations suffers strong erosion although a protection project was realized in the late 20th century. The design of this protection project included the construction of segmented porous structures (brushwood fences) parallel to the shoreline. Their purpose was to damp the incoming energy of wind-generated waves and to protect the shoreline against additional erosion. In order to enhance the shoreline protection, an additional study, based on in situ analysis of wind, waves and bathymetric evolution and numerical modeling of wave field and nearshore wave generated current responsible of sediment transport on the other hand, was carried out. The results revealed that by an adaptation of the existing system an enhancement can be achieved in order to thwart any further erosion and to promote sediment deposition at the leeside of the fences.