Abstract
Soil erosion is a dynamic process where productive topsoil is removed causing loss of land productivity and reduction in storage capacity of surface water bodies. Soil erosion is one of the major causes of land degradation in most areas of Sri Lanka. Therefore, the assessment of erosion hazard of different areas of Sri Lanka is a necessity to apply appropriate conservation measures and combat the land degradation. This study focused on mapping of erosion hazard zones by combining Geographic Information System (GIS) data along with In VEST model. Soil erosion hazard zone maps were developed for each district and for whole Sri Lanka. Results showed that 11.8% of the area in Sri Lanka is under high hazard level of erosion and 4.8% of the area is under very high level of hazard which are intolerable for any land use with respect to the sustainable productivity. Furthermore, six districts namely Badulla (36.5% high erosion hazard), Kandy (32%), Kegalle (38.5%), Nuwara Eliya (40.7%), Rathnapura (38.7%) and Matale (20.3%) showed considerable susceptibility for soil erosion mainly due to the topography and the land use. Four other districts namely, Galle (20% high erosion hazard), Matara (20%), Kaluthara (20%) and Colombo (9%) also showed high tendency for soil erosion due to the land use changes with the urbanization. These areas should be given priority when implementing soil conservation practices and land use changes to reduce further soil loss.