Evolution of multivariate drought hazard, vulnerability and risk in India under climate change

Changes in climate and socio-economic conditions can induce water stress and threaten water security. India is an agriculture-dependent, densely-populated country undergoing rapid societal developments. For proper mitigation and adaptation planning in India, it is, therefore, important to assess how drought hazard, vulnerability and risk would evolve in future. Earlier studies present projected drought risk over India based on frequency analysis and/or hazard assessment alone. This study investigates future evolution of drought risk integrating vulnerability and hazard information at a country-wide scale under the mitigation (RCP2.6) and medium stabilization (RCP6.0) climate scenarios in combination with Shared Socio-economic Pathway middle-of-the-road (SSP2) socio-economic condition. A multivariate standardized drought index (MSDI) based on joint deficits of precipitation and soil moisture is chosen to characterize droughts. Drought vulnerability is assessed by the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method, a robust multi-criteria decision-making technique, considering indicators that represent exposure, adaptive capacity and sensitivity.  Though there is a reduction in areal extent of high or very high drought hazard classes in the country by approximately 7% in future, possibly due to projected rise in precipitation, the area under high or very high drought vulnerability classes increases by 33% in the worst-case scenario. Parts of West Rajasthan, Odisha, Haryana and West Uttar Pradesh are found to be high risk under all scenarios. Bivariate choropleth plots show that future drought risk is more significantly driven by changes in vulnerability resulting from societal developments rather than climate-induced changes in drought hazard. The present study can aid the administrators, policy makers and drought managers in formulating decision support systems for effective drought management.