Hydroclimatic Parameter Shifts and Their Impact on Maize Production: A Multi-Decade Assessment in Akşehir/Türkiye

The intensifying effects of climate change on soil hydrology and agricultural water use require comprehensive understanding for sustainable maize production, a key crop in Türkiye's agricultural system. This study combines empirical trend analysis with AquaCrop model simulations under the RCP 4.5 climate change scenario to investigate the complex interactions between climate change, soil-water dynamics, and agricultural water footprint (WF) of maize cultivation from 2004 to 2022 in a major agricultural region (Akşehir) of Türkiye, providing critical insights for irrigation management and food security.

Through Mann-Kendall tests and Sen's slope estimators, coupled with AquaCrop model simulations, we identified considerable climate change-induced shifts in hydroclimatic parameters affecting soil-water relationships. Reference evapotranspiration (ET₀) showed a significant decreasing trend (τ = -0.43) with a decline of 2.7 mm/year, while crop evapotranspiration (ETc) exhibited an even stronger declining pattern (τ = -0.58) with a decrease of 2.8 mm/year. These trends occurred against a backdrop of significantly increasing atmospheric CO₂ concentration (τ = 1.000) with an annual increase of 2.1 ppm/year.

The analysis of WF components revealed promising trends for sustainable water management under changing climate conditions. The unit blue WF showed a significant decreasing trend (τ = -0.35) with an annual reduction of 4.27 m³/ton, indicating improved irrigation efficiency, while the unit total WF demonstrated a strong declining trend (τ = -0.58) with a decrease of 2.7 m³/ton/year. Although the unit green WF showed a slight increasing trend (τ = 0.17) with an annual increase of 1.17 m³/ton, this shift from blue to green water use suggests a positive transition toward more sustainable water management practices in a changing climate. This favorable redistribution of water sources, combined with improved irrigation efficiency, has supported agricultural productivity, as evidenced by the marginally significant increasing trend in maize production (τ = 0.39).

While these findings demonstrate successful adaptation of maize cultivation systems to changing climatic conditions in our study region under the RCP 4.5 scenario, broader country-level and global analyses are essential to understand geographic variations in water productivity and potential shifts in agricultural suitability under climate change. These spatially explicit insights would be valuable for developing targeted adaptation strategies and ensuring sustainable food production across different agro-ecological zones. Our results highlight the importance of regional-scale studies in understanding climate-water-crop interactions and emphasize the need for integrated approaches to enhance agricultural water productivity while maintaining environmental sustainability in the face of accelerating climate change.

*Key Words:* Climate change, water footprint, AquaCrop model, soil hydrology, maize production