Soil loss assessment in the Tasik Chini catchment, Pahang, Malaysia

Abstract

The Universal Soil Loss Equation (USLE) model is used to estimate average soil loss generated from splash, sheet, and rill erosion in agricultural plots at the Tasik Chini catchment. Use of the USLE has recently been extended for predicting soil loss and plan control practices in agricultural catchment by the effective integration of Geographic Information Systems (GIS) based on procedures to estimate the factor values in a grid cell basis. This study was performed to predict the soil erosion risk by the USLE/GIS methodology for planning conservation measures in the site. Rainfall erosivity (R), topographic factor (LS) and land cover management factor (C) values for the model were calculated from rainfall data, topographic and land use maps. Soil was analyzed for the soil erodibility factor (K). Soil samples were selected from the eleven soil series around the Tasik Chini area. A total of 55 samples were collected from the eleven soil series namely Tebok, Lating, Serdang, Kuala Brang, Kedah, Bungor, Kekura, Malacca, Rasau, Prang and Gong Chenak. Physical properties such as particle size distribution, texture, hydraulic conductivity and organic matter content (OM) were analyzed in order to support the erosion rate analysis. Results shows that five soil series have low rates of soil loss, i.e. Tebok, Lating, Bungor, Kekura and Gong Chenak series, having an average soil loss of 0.65, 0.10, 1.61, 4.23 and 0.53 ton/ha/year, respectively. Two soil series have moderate rates of soil erosion namely Serdang and Prang series (average of 47.41 and 41.10 ton/ha/year, respectively). Two soil series with moderately high rates of soil loss are Kuala Brang and Rasau soil (average of 57.16 and 57.93 ton/ha/year, respectively). Malacca Series has high rate of soil loss, ranges from 21.44 to 348.7 or average of 130.26 ton/ha/year. Kedah soil series has very high soil loss, ranges from 79.99 to 319.75 or average of 180.49 ton/ha/year. This high erosion rate is expected to generate higher sedimentation rate into the Tasik Chini water body, elevating the lake fills and eventually forming an extinct lake.