Soil erosion in the Buyuan basin, Upper Mekong: Based on RS/GIS and RUSLE

Revised Universal Soil Loss Equation (RUSLE) associated with GIS/RS technology has been widely applied to estimate regional soil loss around the world. However, In the Buyuan river basin, the largest tributary within the Upper Mekong, little work has been conducted to assess the situation of soil erosion, though it plays considerable roles for sediment supply to the Lower Mekong after cascade dams have been built in the mainstream of upper Mekong. This work employed RUSLE with GIS/RS to investigate soil erosion in the Buyuan basin during 1989-1999. Results indicate that the total area of soil erosion is larger, accounting for 90% of the total catchment area; annual average erosion modulus of 1989 is 19.996 (t / (km² · a)), and 17.364 (t / (km² · a)) in 1999; soil erosion load is about 1.53 × 10⁷ t and 1.33 × 10⁷ t in 1989 and 1999 respectively; According to the Standards for classification and gradation of soil erosion in China, slight and light erosions occupy most area of the basin and increase by 193.99 km² and 0.22×10⁶ t from 1989 to 1999. During the period, On the contrary, the other classifications (i.e. medium, strong, extremely strong and acute) of erosion reduce by 193.99 km² and 2.24×10⁶ t respectively. Generally, the situation of soil erosion in this tributary basin was becoming better due to effective contemporaneous the soil and water conservation measures.