Sediment yield from a tropical mountainous watershed by RUSLE model, An insight for sediment influx into the tropical estuary

Sediment yield is the possible volume of sediments that a basin is capable of delivering to its watershed outlet. It is a function of the topography of the drainage basin, climate, including precipitation, land use- land cover, soil characteristics, and other factors associated with the rate of soil formation and its transportation. Modeling sediment yield from a watershed enables computing quantitative estimates of sediments generated from a watershed. The Revised Universal Soil Loss Equation (RUSLE) is an efficient model for the assessment of annual soil loss from a basin using remotely sensed data in the Geographical Information System (GIS) platform. In the present study, the assessment of sediment yield from the Gangolli river basin of Karnataka, located on the central west coast of India, is carried out based on satellite data, processed in the GIS platform following the RUSLE model. The basin has a relief of 1200 m and a total catchment area of 1513.04km2, spread on the western face of the Western Ghat region of the South Kanara district. The basin is located in a tropical environment and experiences a hot humid climate and annual precipitation of ~ 355 cm. Physiographically, the basin is divided into three subdivisions; the high-relief mountainous region of the Western Ghats, the residual hilly region with low relief, and the coastal plains. The basin has a high circularity Index (0.25) and a moderately high elongation ratio (0.51). The total actual sediment yield from the basin has been estimated to be 6,32,976.38 tons/yr-1 and the potential yield is 23,26,047.61 tons/yr-1. implying high sediment flux into the estuarine system. The results of this study help to strategize inland soil conservation planning as well as estuarine management.