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

Abstract

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

Victoria-Randenigala area was chosen in this work. as it is the major catchment of theMahawcli River which stretches the entire central hill country. With the use of SPANSGIS.information on erodibility. erosion potential. catchment natural stability. strictprotective areas and recommended forms of land-use were readily identified. Details of thefindings show that X4% ofthe area lies Ol'CF J ,()()O{I. Contour and 19% at >30% slopeclass. About 4Y!r; of the catchment area is at high erodibility risk despite 39'/{; existingforest cover. due 10 land degradation. Only 36% of the catchment area is considerednaturally stable. Hence protection priority should be given to 68% of the catchment area.To conserve the catchment, 31 (In of the area must be afforested and 40% must he plantedwith perennial crops or forest species.

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