Configuration Dredging — An Alternative to Groynes & Offshore Breakwaters

Abstract

The impact of dredging in the near-shore zone on beach stability has all too often not been understood. The scenario typically involves dredging of a new channel for a port, where the commercial value of the port is high and the designers of the port are not aware that a localised deepening of the seabed can dramatically change the direction of waves passing over the dredged hole. Projects involving such ‘errors’ are rarely publicised. However, if dredging can change near-shore wave characteristics resulting in beach erosion, it must also be possible, by designing the shape of a dredged hole, to create changes to the near-shore waves which promote beach stability. This paper describes such an example and how ‘configuration dredging’ can influence longshore sediment transport in a manner similar to groynes and offshore breakwaters. The paper also outlines the general applicability of the concept.