Scaling of Short Duration Extreme Precipitation and Streamflow Over Major River Basins of India

The Clausius-Clapeyron (CC) equation implies 6-7% increase in extreme precipitation per degree rise in temperature. In practice, the extreme precipitation rate (with temperature) deviates from the CC rate. India has seen an increase in the rate of short-duration extreme precipitation and associated flash flood events in recent years. Many Indian River basins are susceptible to tropical depressions, which can lead to severe storms and extreme precipitation-induced flash floods. However, potential impact of climate warming on extreme streamflow events and associated flood in different climatic regions remains unexplored. Using ERA5-LAND reanalysis hourly data of precipitation, runoff, near surface air temperature (SAT), we simulated the streamflow of more than 220 gauge stations located across India. We observed the negative scaling of daily extreme precipitation with SAT, and positive scaling of short duration extreme precipitation with SAT over warm tropical regions. The streamflow-temperature scaling remains positive with super-CC scaling for smaller catchments and sub-CC scaling for large catchments. In a warmer climate, flash floods provide a greater hazard corresponding to smaller catchments especially, which need to be assessed by analyzing short duration precipitation extremes rather than daily precipitation extremes. Our finding suggests the consideration of appropriate risk factors during design and planning of hydraulic structures at critical zones against the threat of flash flood.