Forestry and Environment Sympoisum 1998, Sri Lanka

Fourth Annual Symposium organized by Department of Forestry and Environment Science, University of Sri Jayewardenapura, Sri Lanka.

Thursday, October 05, 2006

GIS IN SOIL EROSION - MODELLING OF VICTORIA - RANDENIGALA CATCHMENT,SRI LANKA

H G Gunawardana
Forest Department, Battaramulla.

Land and water resources are the backbones of an agricultural-based country like ours. Their role in national productivity, however, depends on how we manage them. Appropriate management alternatives are the result of technically sound decisions. With the aid of a resource-based computer program like SPANS-GIS, such decisions arc readily drawn after input variables are integrated into the program.

Victoria-Randenigala area was chosen in this work, as it is tile major catchment of the Mahaweli River which stretches tile entire central hill country. With the use of SPANS-­GIS, information on erodibility, erosion potential, catchment natural stability, strict protective areas and recommended forms of land-use were readily identified. Details of the findings show that 84% of the area lies over 1000fi. Contour and 19% at >30% slope class. About 43% of' the catchment area is at high erodibilily risk despite 39% existing forest cover, due to land degradation. Only 36%, of the catchment area is considered naturally stable. Hence protection priority should be given to 68% of the catchment area. To conserve the catchment 31% of the area must be afforested and 40% must be planted with perennial crops or forest species.

SPANS-GIS proved useful in identifying key elements necessary in managing Victoria­ - Randenigala catchment. It is a valuable tool in providing information that helps man in managing land and water resources.

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