Rainfall variability and its impact on sediment discharge from the rivers of Kerala region, Southwestern India

Because of the direct connection between rainfall and both erosion and transport of sediments, variations in rainfall are likely to affect both processes. Factors governing rainfall variation during the last 100 years, and the role played by rainfall in erosion and fluvial sediment discharge of Kerala Rivers during the last 20 years have been investigated. Rainfall variation during the last 100 years over Kerala suggests that the annual rainfall has decreased in the last five decades. Geographical variation is also documented with a higher rainfall in northern Kerala. Further, physiography, particularly the Sahyadri (Western Ghats) mountain range, plays an important role in the spatial distribution of rainfall. There is a positive relation between rainfall variability, run-off and sediment discharge of the rivers of Kerala. It can be suggested that the geomorphic features of the landscape play an important role in the supply, transport and deposition of sediments in coastal areas, including continental shelf.