Characterization of Regional Drought Over Water and Energy Limited Zones of India Using Potential and Actual Evapotranspiration

Abstract

AbstractUnderstanding the drought characteristics is critical for water resources management in water stressed countries such as India. Previous studies evaluating drought assessments over India considered precipitation (P) and potential evapotranspiration (PET) as drivers using standardized precipitation‐evapotranspiration index (SPEI). The suitability of actual evapotranspiration (AET), which accounts for both water and energy based evaporative demands, in drought characterization is limited. In this study, SPEI is restructured with AET to characterize the regional drought over water and energy limited regions as standardized precipitation actual evapotranspiration index (SPAEI). For this, AET estimated based on Budyko framework and remote sensing‐based AET data has been used. The original formulation of SPEI is limited toward capturing the seasonality present in P and PET. The SPEI is restructured to account for the water availability deficit in the drought assessment rather than the actual atmospheric water demand in a given period to capture the strong seasonality of rainfall. The study compared the drought characteristics with both PET and AET for various meteorological homogeneous zones of India, which are characterized as water‐limited (Central, North, West, South, and Jammu and Kashmir, J&K) and energy‐limited (Northeast and Northeast hills) zones. Overall, the proposed new drought index based on AET can be promising toward drought intensity, extreme drought areal extents, shorter‐time scale drought frequencies, and longer‐time scale drought durations for water‐limited zones. The proposed drought indices based on AET can be robust for the drought assessment under consideration of water energy along with land and vegetation variability and can provide more insights for water‐limited regions.