Experimental study on wave-induced scour in front of sloping coastal structures and the influence of bed protection

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Abstract

The erosion of the seabed in front of coastal structures induced by waves can lead to multiple types of failure instability or function of the structure. On this topic most research has been done into erosion in front of vertical structures. For sloping structures a knowledge gap exists in the understanding of the processes that lead to erosion of seabed material directly in front of the structure. In this report the structural and hydraulic paramters that influence the development of a scour-deposition pattern in front of sloping structures is tested. For this model tests have been done in the wave flume of the laboratory of Hydraulic Engineering at Delft University of Technology. This has resulted in a design formula that can be used for a first estimation of the maximum scour depth in front of sloping coastal structures where bed-load transport is dominant. Parameters that are used in determining this depth are the number of waves, the incident significant wave height, the relative water depth and the reflection coefficient of the structure. Performance of the formula with the model test results is good.