DEGREE OF LAND DEGRADATION IN THE UPPER MAHAWELI CATCHMENT AREA (AN INDICATIVE MAP GENERATED USING GEOGRAPHIC INFORMATION SYSTEMS)

Abstract

The Upper Mahaweli Catchment (UMC) is located in the central hills of Sri Lanka. Totalsurface area is 3110.81 Km2 with the sub-catchments of Kotmale, Victoria, Randenigalaand Rantembe. During the past few decades, land degradation has increased due tochanges in plantation agriculture, population growth and inappropriate land managementpractices on steep slopes in the UMC area.

This study was carried out to identify land quality in three basic levels: degraded lands,degrading lands and good lands in the UMC area. From the agricultural perspective, theeffect of land degradation could be linked to the natural fertility levels of the land or cropyield characteristics. As such data was not available, present land cover and slope wereused as indicators of land degradation. Assumption is that, land cover could be taken as acumulative result of fertility levels, natural quality of soils & climate and anthropologicalimpacts. Accuracy was checked by field investigation.

The results of this study can be useful for watershed management, agricultural resourcesmanagement and planning, to develop guidelines and policies.