Assessment of soil erosion and sediment delivery ratio in the Arghandab Catchment, Kandahar Province, Afghanistan by using GIS-based RUSLE method

Abstract

A significant proportion of Arghandab Catchment in Kandahar Province, Afghanistan has been under potential degradation threat due to soil erosion. This study assessed the extent of soil erosion and estimated the sediment delivery ratio (SDR) in the catchment by employing the Revised Universal Soil Loss Equation (RUSLE), utilizing the Geographic Information System (GIS) and the Remote Sensing (RS) techniques. Data, related to rainfall erosivity (R factor), soil erodibility (K factor), slope length and steepness (LS factor), cover management (C factor), and support practices (P factor), employed for the RUSLE model were processed using the GIS tools and R-Studio software. Average RUSLE factor values estimated in the studied area ranged from 51.8 to 124 MJ mm ha-1 h-1 year-1, 0.03725 t ha h ha-1 MJ-1 mm-1, 9.2, 0.445, and 0.75 for R, K, LS, C, and P factors, respectively. The results revealed that the average annual soil loss from the catchment was 6.81 t ha-1 yr-1, ranging from 0.002 t ha-1 yr-1 in the flat areas up to 94.7 t ha-1 yr-1 in the hilly and mountainous regions. Soil classes of slight, moderate, high, very high, severe, and very severe covered areas of 20.1% (263,542.3 ha), 12.2% (160,286.5 ha), 22.8% (298,740.6 ha), 20.3% (265,546.8 ha), 17.6% (231,224.4 ha) and 6.9% (90,879.9 ha), respectively. The computed SDR for Dahla Reservoir located in the catchment was found to be in between 24.2% and 36%. LS factor was identified as the most crucial variable associated with soil erosion. The findings from this study can be applied when designing effective conservation strategies in the management of erosion and water management.