Irrigation adaptation for crop production under climate change a modeling study in North America

Under global climate change conditions, Irrigation demand is expected to incline to maintain a high-level crop production, especially encountering extreme drought events. The increasing demands for agricultural water use will further deplete terrestrial water storage. In this study, we intend to answer two scientific questions: (1) How much water is needed for irrigation under future climate condition? (2) What is the impact of these irrigation demands on terrestrial water cycle, such as groundwater, soil moisture, and evapotranspiration. To answer these two questions, we conducted simulations using the Noah-MP land surface model, which dynamically model both crop growth and irrigation, under current and future climate conditions. For both experiments, the meteorology forcing are from high-resolution convection-permitting regional climate simulations at 4-km resolution, CONUS I. As one of the worlds largest food baskets, the study region includes the cropping region of maize, soybean, and wheat across the U.S. and Canada. Two drought periods are investigated in the early 2000s, the 2006 Midwest drought and the 2011 Southern U.S. drought, together with their corresponding impacts by the end of the 21st century under the Pseudo global warming condition (PGW). Our preliminary results show that to achieve the current level of yields for current irrigated regions, climate-induced evapotranspiration demand will increase significantly under future climate condition, leading to a plummeting trend in groundwater storage. For current rainfed regions, future precipitation is not sufficient for crop production, suggesting potential needs to implement irrigation infrastructures. This study has important implications for both agricultural industries and water management agencies, for optimizing cropping and irrigation strategies to maintain crop production and improve water use efficiency