Climate change projections and their implications on water availability for irrigated rice in South Asia

Abstract

This study projected water availability changes and impacts on irrigated rice yield across five South Asian basins under multiple RCP scenarios using CMIP5 ensembles coupled with SWAT and DSSAT-CERES-Rice models. Under RCP8.5-2050, seasonal precipitation declined by 13.6%, ET demand rose by 14.4%, and irrigation water deficit reached 182 mm. Rice yield was projected to decline by 2.1-36.3% depending on scenario, with temperature rise explaining 99.4% of yield variation. Reduced precipitation and increased ET jointly accounted for 58.2% of projected deficit, highlighting the convergence of rising demand and shrinking supply.