Examining alternative crop suggestions under drought conditions induced by the climate change

Abstract

Climate change impacts are becoming increasingly pronounced in Türkiye, with projections indicating further intensification in the coming decades. This study assesses potential hydro-meteorological changes in the Sarıgöl Afşar Dam Basin under RCP4.5 and RCP8.5 scenarios and proposes adaptive cropping strategies to mitigate drought impacts. Observed climate data (1986–2005) were statistically downscaled using NCEP/NCAR reanalysis and ensemble climate models to project temperature and precipitation for 2021–2050. Streamflow was simulated with the Dynamic Water Budget Model (DWBM), which incorporated twelve commonly used potential evapotranspiration (EPOT) equations—temperature-based, radiation-based, and combination approaches—within a precipitation–runoff framework. Model performance was evaluated using RMSE, R2, NSE, RSR, and PBIAS, identifying the Hamon method as the most reliable. Crop evapotranspiration (ETc) and irrigation water requirements (IWR) were estimated for grapevines (the dominant crop) and potential alternatives based on FAO-56 crop coefficients. Results show that continued grape monoculture would increase net IWR by 18.21% under RCP4.5 and 25.93% under RCP8.5 relative to the baseline (1986–2005). In contrast, the proposed mixedcropping scenario—40% grape and 60% olive cultivation—would limit these increases to 11.9% and 15.6%, respectively. Secondary scenarios involving winter wheat and sunflower, evaluated as a comparative reference to illustrate the lower water-demand characteristics of annual crops, also exhibited comparatively lower water demands. Integrating EPOT-based hydrological modeling with climate projections provides a robust framework for irrigation planning and supports the design of resilient, water-efficient cropping systems under future climate conditions.