Water footprint and water productivity dynamics of Mediterranean rice under climate change and water regime scenarios

Abstract

Introduction Rice production is highly dependent on water availability and is increasingly exposed to climate-driven changes in evapotranspiration, precipitation patterns, and irrigation demand.Methods This study evaluated future rice water footprint and water productivity responses using DSSAT-CERES-Rice outputs previously calibrated and validated for Mediterranean conditions in T & uuml;rkiye. The validation-year full-irrigation reference was used to represent future irrigated conditions in the present water footprint assessment. Simulations were evaluated using three GCMs, HadGEM2-ES, GFDL-ESM2M, and MPI-ESM-MR, two emission scenarios, RCP 4.5 and RCP 8.5, and three projection periods: 2016-2040, 2041-2070, and 2071-2098.Results For irrigated conditions, mean green + blue water footprint was highest in 2016-2040, reaching 1250 m & sup3; t(-)& sup1; for RCP 4.5 and 1056 m & sup3; t(-)& sup1; for RCP 8.5, but remained lower in the late-future period, reaching 674 and 668 m & sup3; t(-)& sup1;, respectively, by 2071-2098. For rainfed conditions, mean green water footprint was considerably higher in the near-future period, reaching 6401 m & sup3; t(-)& sup1; for RCP 4.5 and 4610 m & sup3; t(-)& sup1; for RCP 8.5, mainly because limited growing-season rainfall and increased water stress reduced simulated yields under non-irrigated conditions. These values remained below the near-future levels in the late-future period, reaching 1869 and 2608 m & sup3; t(-)& sup1;, respectively, in 2071-2098. Irrigation water productivity ranged from 0.88 to 9.37 kg m(-)& sup3;, indicating strong sensitivity to irrigation water use and yield response, particularly in scenarios with low simulated irrigation requirements.Discussion Overall, future rice water footprint was controlled not only by evapotranspiration, but also by yield response, irrigation regime, and GCM-specific climate responses. The study demonstrates that validated DSSAT outputs can be used not only for future yield projection, but also for water footprint assessment, providing a useful framework for future rice water management under climate change.