SEASONAL CLOSURE OF CHILAW INLET, SRI LANKA: PHYSICAL PROCESSES AND MATHEMATICAL MODELING

Chilaw inlet, with the affiliated lagoon, is located on the west coast of Sri Lanka about 120 km north of the capital Colombo. Each year during the summer monsoon, which lasts from May to September, the inlet closes due to a sand spit forming across the inlet. The morphological evolution at Chilaw inlet was studied during the summer monsoon in order to understand the physical mechanisms governing the process of closure and how to mathematically model it. A measurement campaign was performed from May to July, 2006, resulting in high-resolution topographic maps, from which the morphological changes at the inlet during the monsoon could be deduced. A mathematical model was developed based on the identified sediment pathways at the inlet using a reservoir-type model description to simulate the morphological elements including the spit and its growth across the inlet.