Assessment of Suspended Sediment Dynamics in the Largest Peninsular Basin of India

Abstract

The Godavari River Basin (GRB), the biggest Peninsular Indian basin, has experienced a major decline in both streamflow and sediment discharge since 1965, with a particularly notable loss occurring after around 1990. Previous studies reported an overall decrease of suspended sediment load around 123 Mt/year in the GRB, which places it as the third highest among all major river basins worldwide. However, there is a lack of adequate understanding of the consequences of reservoir operations, variations in flow, and the broader dynamics of sediment.  Here, we employed a dataset provided by the Central Water Commission (CWC), India, to better comprehend the fluctuations in suspended sediment load and discharge throughout different regions of the GRB. Our research focuses on analyzing the relationship between the variability of suspended sediment load and its response to factors such as dam constructions and discharge fluctuations. Our research findings indicate that a significant number of gauging stations had a decline of more than 50% in suspended sediment load after 1990. Further investigation clearly demonstrates a substantial decrease in suspended sediment load after 1990 due to the entrapment of suspended sediment load induced by the installation of large-scale dams. The temporal change in suspended sediment load in the Godavari and its main tributaries is associated with the rise in human activities observed in recent decades. The findings of this study have important significance for recognizing the complex relationships between land use land cover, suspended sediment loads, soil erosion, and reservoir management in the GRB.  In addition, this study can provide valuable information for policymakers to adopt more effective reservoir management, soil erosion control, and soil-water conservation measures in the GRB.