Spatial assessment of soil erosion risk using RUSLE and GIS techniques

Abstract

Soil erosion by water is considered a major cause for land degradation in Jordan, where 0.14 cm of productive top soil is eroded annually. This investigation is intended to estimate the annual soil loss in Wadi Kerak watershed, and to examine the spatial patterns of soil loss and intensity, as an essential procedure for proper planning of conservation measures. To achieve these objectives, the revised universal soil loss equation (RUSLE) model has been applied in a geographical information system framework. After computing the RUSLE parameters (R, K, LS, C and P) soil erosion risk and intensity maps were generated, then integrated with physical factors (terrain units, elevation, slope, and land uses/cover) to explore the influence of these factors on the spatial patterns of soil erosion loss. The estimated potential annual average soil loss is 64 ton ha−1year−1, and the potential erosion rates from calculated class ranges from 0.0 to 790 ton ha−1year−1. Soil erosion risk assessment indicates that 54.5 % of the catchment is prone to high to extreme soil losses higher than 25 ton ha−1year−1. The lower and middle parts of the catchment suffer from high, severe, to extreme soil erosion. While 45.5 % of the basin still undergoes slight and moderate levels of soil loss of less than 25 ton ha−1year−1, yet 76.91 % of soil erosion occurred on four different terrain units, and 72.29 % of soil erosion occurred in zones less than 600 m in elevation, with 88 % present on areas of 0°–6°, 5°–15°, and 15°–25° slope categories. 32.6, 30.3, and 33.1 % of soil erosion occurred on rainfed mixed farming and irrigated areas, barren, and rangeland, respectively. The present results provide a vital database necessary to control soil erosion in order to ensure sustainable agriculture in the highland region of Jordan.