Evaluation and projection of drought over India using high-resolution regional coupled model ROM

Drought is a recurring insidious hydro-climatic extreme that adversely affects agriculture growth and leading to long-lasting severe impacts on regional water resources and ecosystem. A comprehensive assessment of drought is possible in a sophisticated manner by advanced climate modelling approaches that enhance process understanding and improve future projections. In the present study, for the first time, a high-resolution regional coupled model (ROM) simulation is used for the representation and projection of meteorologoical, agricultural and hydrological drought over India till the end of the twenty-first century. ROM is evaluated against observations for hydroclimatic variables and is observed to reasonably capture the variations of precipitation for ~ 80% area followed by runoff and soil-moisture with a significant correlation over most of the regions for the historical period. In particular, ROM precipitation has considerable improvement for ~ 70% (~ 52%) area compared to GCM (RCM). The correlation between standardized precipitation index and standardized runoff index is quite high (0.92), while the standardized soil-moisture index exhibits a slight reduction (0.82), though statistically significant. In the future, the spatial patterns of droughts are very similar, though uncertainties are observed in severities derived by lag responses of driving variables. The dryness is mostly projected over Northern India (NI) and Southern Peninsula which poses a great threat of agricultural drought followed by hydrological and meteorological drought. This higher drought severity over NI is associated with the weakening of monsoon circulation in the Bay of Bengal due to reduced thermal gradient. This study demonstrates that ROM is an efficient tool for future drought studies at a regional scale for adequate water resources security and management.