On the Changing Role of Climatic Drivers to River Basin Scale Flooding

Floods result from the interplay of climatic drivers, catchment characteristics and river system dynamics. The observed shift to extreme climatic events necessitates a better quantification of their impact on flood generation. Improving our current understanding of flood generation processes in the observed climate provides a pathway to improve flood projections in a warming climate.

This presentation will share insights from our work on river basin scale flooding in India. Using a physical hydrological model, we conducted an event-scale analysis of high flows across multiple river basins in India. The results highlight the significant role of antecedent catchment moisture, as well as the duration and spatial extent of precipitation events, in driving river basin scale flooding. The study also examines and distinguishes the relative importance of large-scale moisture transport, and origin, persistence and direction of propagation of low-pressure systems in triggering localized and widespread floods. Furthermore, we find that prominent flood drivers in a warming climate are similar to those observed in the historical period. Careful attribution of observed flood changes, combined with a thorough assessment of changes in key drivers, is essential for deriving reliable projections of future flood risk.