Interference of natural coastal sediment dynamics due to the Colombo harbour expansion project

Abstract

Man-made coastal structures directly affect sediment balance in the surrounding beaches. Ongoing South Colombo harbour expansion project has created 5 km long breakwater affecting the sediment dynamics of the Colombo beaches. Present study is focussed on quantitatively and qualitatively analyse the effect of Colombo harbour expansion project on economically important beaches in an around Colombo city area and to forecast possible consequences to the Colombo harbour itself. We have taken monthly variations of beach width, beach profile and the mean grain size of the sediments at mean sea level from selected 8 beaches. Data was processed and analysed to establish sitespecific erosion vulnerability. Results shows cumulative beach erosion has high affinity to erosion causing drastic reduction of beach width after the construction of the breakwater. This study highlights necessity of proper mitigation plan to protect the beaches affected by the construction of southern Colombo harbour expansion project.