Soil Erosion and Sediment Yield Assessment at Sub Watershed Scale in an Ungauged Basin Based on Impacts of LuLc Changes

Abstract

Soil Erosion (SE) is one of most important threat to natural resource on Earth which detrimentally impacts crop productivity, leads to the loss of habitat, affects biodiversity and has a negative effect on the socio-economic development of the area under consideration. On other hand, sediment yield (SY) refers to the quantification of eroded soil particles that reaches outlet of a river basin. Assessing SE and SY in an ungauged river basin is crucial for effective watershed planning, management and soil and water conservation measures. By utilizing Remote Sensing (RS) and Geographic Information System (GIS) and empirical approach, erosion and yield mapping can identify vulnerable regions and reveal the geographical pattern of soil loss across degrading sites. The accurate identification of SE and SY prone areas at the sub-watershed (SW) scale is vital for addressing these issues effectively and evaluating the extent of soil degradation comprehensively. In the current study, Ponnaniyar River basin has been chosen as the study area, which is a tributary of Cauvery of South India. It is a non-perennial river with poor terrain conditions and is located in an ungauged basin. The main aim of this study is to assess the SE and SY at sub-watershed scale based on land use/ land cover (LULC) changes with limited datasets. The LULC of selected river basin was classified for the year 2021 by using different traditional and machine learning classifiers and its accuracy was assessed using statistical methods. The annual rate of soil erosion was studied using the Revised Universal Soil Loss Equation (RUSLE) model based on various LULC classifiers. The comparative study made between the RUSLE based Sediment Delivery Ratio (SDR) and Modified Universal Soil Loss Equation (MUSLE) at SW scale was done to identify the suitable SY model with study area. Using grade average method, the SWs susceptible to severe SE within basin were assessed and prioritized by integrating different combination. newline