Drivers of widespread floods in Indian river basins

Abstract

Widespread floods affecting multiple subbasins in a river basin have implications for infrastructure, agriculture, environment, and groundwater recharge. However, the crucial linkage between widespread floods and their drivers remains unexplored for Indian sub-continental river basins. Here, we examine the occurrence and drivers of widespread flooding in seven Indian sub-continental river basins during the observed climate (1959-2020). The peninsular river basins have a high probability of widespread flooding, compared to the transboundary basins of Ganga and Brahmaputra. Favorable antecedent baseflow and soil moisture conditions, uniform precipitation distribution, and precipitation seasonality determine the probability of widespread floods in Indian river basins. The widespread floods are associated with large atmospheric circulations that cause precipitation in a large part of a river basin. Our findings highlight the prominent drivers and mechanisms of widespread floods with implications for flood mitigation in India.