Dynamics of the Madu-Ganga Estuary

Abstract

Among the estuaries in Sri Lanka, Madu-Ganga Estuary plays a significant role to generate a massive income through tourism. The existing tropical ecosystem attracts the tourists. However, this ecosystem faces problems of environmental deterioration problems which affect the tourism industry and income of the local community. Therefore, this research is mainly focused for understanding hydro dynamics and sediment dynamics process in Madu-Ganga Estuary. The four field visits were carried out to cover southwest and northeast monsoon periods. In situ and laboratory tests were conducted for surface and bottom water samples of Madu-Ganga Estuary to analyse the quality of the water. In addition, grab and core samples and sub-bottom profile data were used to identify sediment distribution patterns of the estuary. Moreover, time series satellite images were used to identify nearshore sediment dynamics along the western coast of Sri Lanka. Results show that a significant variation of water quality parameters under the estuary mouth opened and closed conditions. The spatial variation of chloride content also indicates that estuary mouth opened condition plays a major role to control seawater invasion in this aquatic system. Sub-bottom profile data shows cyclic/seasonal changes in accumulation of sediments in Madu-Ganga Estuary. Time series satellite images indicate that sand can probably receive from the southern region by predominant longshore currents during the southwest monsoon. Further studies are recommended to identify lake ecosystem responses to physicochemical changes and to design seasonal mining capability.