Dynamics of streamflow and sediment load in Peninsular Indian rivers (1965-2015)

The streamflow and sediment load in natural rivers around the world are undergoing significant changes due to the present climate change and anthropogenic activities. Therefore, for the management of water resources, soil conservation practices, and regulating coastal erosion; it is crucial to identify spatio-temporal variability and dynamics of streamflow and sediment load in natural rivers. The inherent characters of the tropical rivers in Peninsular India are not extensively studied. This paper examines temporal variation in streamflow, sediment load, and sensitivity of landscape complexity in varying sediment yield in 12 major tropical rivers in Peninsular India. About half-century of daily time-series records have been assessed to compute annual variabilities, trends, and abrupt changes through Mann-Kendall and Pettitt tests. Partial least squares regression has been employed to determine dominant drivers of sediment yield from a large number of topographic and climatic variables. The results indicate that concerning the global river runoff and sediment flux, 12 major Peninsular Indian rivers contribute less than 1% water and little more than 1% sediment to the world oceans. During the past five decades, a significant decrease in streamflow is found in Krishna, Cauvery and Narmada rivers and the changes are associated with variation in precipitation. After 2000, sediment load in almost all rivers has declined more than 40%. Construction of numerous high capacity reservoirs and dams have a significant influence on the reduction of sediment load. Profile curvature, plan curvature, relief, average elevation, circularity ratio and average annual rainfall explain the most among numerous other topographic and climatic variables with relation to the sediment yield in Peninsular India. The present study is intended to elucidate the dynamics of streamflow and sediment load during the past five decades and bridge knowledge gaps of the dynamic nature of Peninsular rivers in India.