Vulnerability of water availability in India due to climate change: A bottom-up probabilistic Budyko analysis

Abstract

Quantifying the dependence of future water availability on changing climate is critical for water resources planning and management in water stressed countries like India. However, this remains a challenge as long-term streamflow data are scarce, and there are significant uncertainties regarding future climate change. We present a bottom-up probabilistic Budyko framework that estimates the vulnerability of available water to changing climate using three hydroclimatic variables: long-term precipitation, potential evapotranspiration, and actual evapotranspiration. We assimilate these variables within a probabilistic Budyko framework to derive estimates of water availability and associated uncertainty. We then explore a large range of possible future climates to identify critical climate thresholds and their spatial variation across India. Based on this exploratory analysis, we find that southern India is most susceptible to changing climate with less than 10% decrease in precipitation causing a 25% decrease in water availability. Key Points We develop a bottom-up probabilistic Budyko framework and test it in a data scarce region, India We assess critical climate thresholds for vulnerability of water resources across India We find high susceptibility of southern India to decreasing precipitation.