Impact of shipwrecks on the morphology of world coasts: A Review

Role of the grounded ship MV River Princess in activating erosion along the Candolim to Sinquerim coast of Goa, India, is evaluated. Beach and dune system was severely affected, as over a kilometre long strip of coastal sand dunes were destroyed. Results suggest that the wreck acted like an offshore breakwater, trapped sediment around the site, and created a sediment deficit with consequent erosion south of the site. Coastal retreat occurred at a rate of 7 to 8 m/year, over a period of 10 - 12 years, along 1.5 km of sea front. A comparison of the impact of similar grounded vessels around the globe confirms that shipwrecks in shallow seas have the potential of drastically altering the face of the coast, often within a short time. Major factors that determine the fate of the coast subsequent to a shipwreck are: distance of the wreck from the shore, the depth of water, the span of time when the wreck remains aground, the orientation of the vessel with respect to the shore, the direction and intensity of prevailing winds, the consequent wave regime, the resultant littoral currents and the disruption of sediment transfer along the shore. The kind of short-term coastal erosion witnessed in Goa as a consequence of a marooned vessel appears unprecedented in comparison to similar examples found worldwide.