CAS-Climate: To Irrigate or Not? Assessing Climate Change Adaptation for Sustainable Water-Agriculture Systems in the Mississippi River Basin

The Mississippi River basin (MRB) is a region where complex water, agricultural, and environmental challenges are rapidly emerging and are expected to be exacerbated by climate change. Agricultural intensification has enabled consistently upward crop yield trends, but at the cost of many adverse impacts on water resources (e.g., groundwater depletion) and ecological systems (e.g., Gulf hypoxia). In the primarily rainfed agroecosystems in the eastern MRB, sustaining crop yield trends under future climate could require substantial irrigation expansion. Conversely, in the western MRB—particularly over parts of the High Plains Aquifer (HPA)—intensive groundwater irrigation is causing aquifer depletion. Thus, sustainable agricultural intensification in the divergent MRB agroecosystems under future climate will likely require adaptation strategies that involve transitions from rainfed to irrigated farming and vice versa, which will have profound implications on the intricately interwoven water, agricultural, nutrient, and ecological systems. This project will address this complex water-agriculture-nutrient nexus challenge by examining the effectiveness of various agricultural adaptation measures under a range of climate change scenarios. It will engage K-12 students in outreach activities related to pressing water-food-environmental issues in the US, provide computational research opportunities for undergraduate students, and train graduate students at the interface of multiple disciplines. Results will be disseminated through peer-reviewed publications, extension activities at two universities, and conference presentations. Outcomes will be relevant to critical problems faced by farmers, water managers, and broader MRB communities. The project objectives are to (i) assess the need, potential, and feasibility of irrigation expansion in the eastern MRB to sustain food production under climate change, (ii) quantify water scarcity under sustained irrigation and future climate in the western MRB, (iii) assess plausible agricultural adaptation strategies to reduce water stress across the HPA, and (iv) quantify the changes in green, blue, and gray water footprints across the entire MRB under various adaptation and climate change scenarios. The project will use a newly integrated hydrological-agricultural-ecological modeling framework based on the Community Land Model version 5 (CLM5), capable of simulating surface water, groundwater, crop growth, agricultural management, irrigation, reservoir operation, and nutrient flow processes over large domains. The framework will offer novel capabilities to study the co-evolution of water, agriculture, and nutrient systems under climate change and assess alternative water and crop management practices at relatively high resolution, yet over large domains. The study will generate new knowledge on sustainable agricultural intensification across the divergent eastern and western MRB agroecosystems using climate change adaptation measures that holistically consider water resource sustainability and basin-wide gray water footprint. The novel systems modeling approach will contribute to advancing research on coupled natural and human systems toward next generation Earth system science. This award is co-funded by the Environmental Sustainability and Hydrologic Sciences programs. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.