Siltation and Coastal Erosion at Shoreline Harbours

Abstract

One of the major maintenance problems encountered by the shoreline harbours along east coast of India is siltation of approach channels due to huge longshore sediment movement by wave action along the coast. Wave induced longshore sediment transport rates along east coast of India at selected major shoreline harbours Chennai, Visakhapatnam and Paradip have been estimated using an energy flux method. The direction of littoral drift is generally from south to north during the period March to October when southwest monsoon blows over Bay of Bengal and reverses its direction from north to south during the period November to February during northeast monsoon season. The rates of sediment transport however vary from one shoreline harbour to another depending upon the wave climate and other near shore features. While the littoral drift rates are high during south west monsoon season from March to October at Visakhapatnam and Paradip harbours, the Chennai harbour on the other hand experiences high rates of littoral drifts during north east monsoon months particularly from November to January due to storm waves along the coast. The estimated sediment transport rates have been compared with the available dredging quantities to know their accuracies. The problems of siltation and coastal erosion have become severe over the years due to deepening of the harbour channels as a part of expansion and modernization of ports. Hence, a detailed study on siltation problems faced by the shoreline harbours will definitely useful not only for dredging management plan for existing ports but also for planning new port locations along the coast. The historical problems of the shoreline harbours due to construction of harbour installations at selected important ports along east coast of India have been discussed briefly.