Spatially distributed soil losses and sediment yield: A case study of Langat watershed, Selangor, Malaysia

Abstract

Soil erosion is one of the major environmental issues faced globally, causing other environmental-related problems, such as loss of fertile soil, reduced water quality, and reduced reservoir capacity. The objective of this study is to model the potential soil erosion and sediment yield in the Langat watershed, Selangor, Malaysia. Geographical Information System (GIS) is used to spatially map the Revised Universal Soil Loss Equation (RUSLE) parameters, erosion map and sediment yield (SY) in the study area. The models were calibrated using ground truth data obtained from field sampling conducted at the vicinity of the Langat watershed. RUSLE prediction estimated that the average soil erosion rate at the Langat watershed was 67 t ha−1 yr−1 with 68% (1517 km2) of the study area classified at very low risk, 16% of low risk (364 km2), 5% of moderate (121 km2), 3% of the area with high risk (65 km2) and 8% of very high risk of erosion (172 km2). The average sediment yield produced at the outlet was 9 t ha−1 yr−1. The accuracy assessment conducted using Kappa coefficient showed a strong positive correlation with khat = 0.83 for image classification. Based on the spatial assessment, the most critical erosion area was situated at the steep slope, and disturbed land use with high precipitation. Results obtained from this study is an assistance for decision makers to take appropriate mitigation action for environmental protection.