Human Impact on Wetland Ecosystems A Case Study – The Mundel Lake and Its Environs – Sri Lanka

Abstract

The Mundal Lake and its environs can be considered as a disturbed wetland system due to excessive utilization of the resources beyond the sustainable limit. The area is located between Puttalam Lagoon (on the north) and the lower basin of the Deduru Oya (river) (on the south). The flat continental shelf on the western margin of the Lake consists of a straight coastline with wide beaches, berms and sand dunes. The old raised dune ridges bound the eastern margin. The Mundal Lake and its surroundings are consisted of different types of landforms, and formation and evolution of these features have a close relationship with local climatic conditions, such as temperature, rainfall pattern, evapotraspiration, wind circulation and salinity levels. All these factors have contributed to the rich biodiversity in and around the lake. Fishermen and farmers are hereditary people in the area. About twenty-thirty years ago, fertile patches of coconut lands were located along the sand barrier and old dune ridges, while mangrove associates and salt marshes associations covered the edges of lagoon and the creeks. But introduction new development activities such as aquaculture farms in recent years have disturbed the physical environment in and around the Mundal Lake. Use of tidal and mud flats and destruction of mangrove patches and salt marshes in large scale to construct prawn ponds are the main human impacts in the area. Damming and destruction of natural cannel network to intake water to ponds as well as to discharge of effluents from the prawn ponds, construction of dykes, canals, pipe lines and electric wire networks are the other destructive activities. Converting ridge and runnels and reclamation of mud flats to cultivate of coconut and other crops, and extraction of ground water thorough deep well to reduce the high salinity of the ponds are also have responsible for raise a number of issues of the area.