Impacts of climate change on cereal irrigation and water productivity in the Yellow River Basin, China

Increasing food demand and water scarcity pose critical challenges to food and water security, exacerbated by climate change. Although substantial progress has been made in crop yield forecasting, limited research has investigated how irrigation water requirements (IWR) and water productivity (WP) respond to changing climate conditions at a basin scale. To address this knowledge gap, we developed an agro-hydrological model to estimate IWR and WP for maize and wheat across the Yellow River Basin (YRB)—a major cereal-producing region in China—under different climate scenarios from CMIP6. Projections indicate that 70% of maize-irrigated areas will experience an increase in IWR of more than 20%, particularly in the lower YRB due to reduced rainfall during the growing season. In contrast, spring wheat IWR is projected to decrease by 12–16% in the western YRB and 5–8% in the northern YRB, depending on irrigation frequency, due to increased rainfall. Although over 90% of the winter wheat-irrigated areas may require less irrigation water in the near future (2021–2060), non-negligible increases in IWR are expected in the far future (2061–2100) in the southern YRB due to increasing reference evapotranspiration (ET₀). These effects increase with higher levels of radiative forcing and longer time horizons. In addition, changes in IWR are most pronounced in humid areas (low ET₀/P ratios), while increases in WP are most pronounced in areas with ET₀/P values around 1.7 for maize and 4 for spring wheat. The implementation of high-frequency irrigation could mitigate large-scale negative effects. These results highlight the need for water-saving irrigation practices to improve water and food security in the YRB.