Estimation of Soil Loss in Nyera Amachhu Watershed using RUSLE Model

Abstract

The Soil erosion is one of the huge destructions to the soil structures. Nowadays, the environment has been threatened by soil erosion in which it declines the degree of soil fertility that can obviously give enormous affect to the agriculture land and eventually the agriculture productivity. On other hand, human settlements have also immensely affected by such problem that occurs near by the settlement that already done and started the living. Such massive problem was the obstacles that people were facing at our study area the Nyera Ama chhu watershed, due to which the necessary conservative actions has become very needed at the place. Though the erosion is very huge destruction to the environment, application of the conservative measure was not a great decision to adopt in every area but taking actions to the area of high susceptibility to erosion would be the priority. There are many factors that affects the soil erosion. Based on the easiness, accuracy and advancement, the Revised Universal Soil Loss Equation model (RUSLE) was adopted to study the area Nyera Ama chhu. This model has got various parameters which includes runoff-rainfall erosivity factor (R), soil erodibility factor (K), topographic factor (LS), cropping management factor (C), and support practice factor (P) that’s contribute to the soil erosions. Those various parameters are computed and prepared from the Geographical information system (GIS) using required data source and methods. The annual average soil loss from the study watershed area was 66.411 t ha^-1yr^-1 and erosivity factor gives the great influence over other parameters to the soil loss in the study area. The soil loss depends upon the soil types and its structures. Clay, Loam, Sandy loam soil were present in the study area. Southern, north-western region of the area has huge loss of the soil and less in mid watershed area and north east region. RUSLE and GIS based approach provide a reliable estimation of soil loss that help in identify the priority area for effective planning and implementation of sustainable soil management practices so reduce soil erosion, particularly for sustainability of the Nyera Amachhu Watershed located in eastern region of Bhutan.