Scour protection design in highly morphodynamic environments

Offshore wind parks are often developed in areas with a highly morphodynamic seabed. In order to keep the pile fixation level within acceptable limits for pile design, sophisticated scour mitigation strategies are required. This paper discusses the scour protection strategy for the Nordergrunde Offshore Wind Farm, where 10m seabed level drops are predicted at some monopile locations. Physical model tests were performed to validate the scour protection design, focussing on correct falling apron behaviour and the stability of the loose rock scour protection. The outcome of the tests showed good correlation with a modified relative mobility parameter. Using this parameter, the scour protection was optimised for the individual pile locations.