Investigation of multi-model spatiotemporal mesoscale drought projections over India under climate change scenario

Projected droughts for 21st century over India have been analysed using precipitation and temperature data obtained from Regional Climate Models (RCMs) under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Standardized Precipitation Index (SPI), Standardized effective Precipitation Evapo-Transpiration Index (SP*ETI) and Standardized Precipitation-Evapotranspiration Index (SPEI) at the timescale of 12-months have been used for drought characterization. The K-means clustering algorithm has been utilized to delineate distinct drought homogeneous regions in India. Trends and periodicities in drought characteristics have also been analysed. The results of this study reveal that increase in evapotranspiration due to projected rise in temperature would play a major role in affecting future drought dynamics in most parts of India. Analysis indicates that computed magnitude of drought intensity, duration and frequency depends on the choice of drought indicator. SPEI drought index has been found to project highest drought risk as compared to other two indices used in this study. North India is more vulnerable to increase in drought severity and frequency in near future. However in far future, most parts of the country, except few southeastern states, are likely to face an escalation in drought severity and frequency. A shift in drought hazard from central India toward southeast-central India is likely to happen with increase in greenhouse gas (GHG) concentration. The areal extent of droughts has been found to be increasing historically which is expected to increase further in future for most parts of the country. Historically, drought dynamics were more influenced by decrease in precipitation. However, in future, the drought dynamics will be significantly influenced by increased evapotranspiration resulting from increase in temperature in spite of likely increase in precipitation. The periodicity analysis indicates inter-annual periodicities influencing monsoon months to be distributed uniformly across all clusters of the Indian subcontinent with dominant cycles of 2-3.6 years. Further, change in periodic cycles of drought due to climate change is found to be insignificant.