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

密西西比河流域（MRB）是一个复杂的水、农业和环境挑战正在迅速出现的地区，预计气候变化将加剧这些挑战。农业集约化使作物产量呈持续上升趋势，但代价是对水资源（如地下水枯竭）和生态系统（如海湾缺氧）产生许多不利影响。在湄公河流域东部以雨养为主的农业生态系统中，在未来气候条件下维持作物产量趋势可能需要大量扩大灌溉。相反，在mrb西部，特别是在高平原含水层（HPA）的部分地区，密集的地下水灌溉正在导致含水层枯竭。因此，在未来气候条件下，不同MRB农业生态系统的可持续农业集约化可能需要适应战略，包括从雨养农业向灌溉农业的转变，反之亦然，这将对错综复杂的水、农业、营养和生态系统产生深远的影响。本项目将通过考察各种农业适应措施在一系列气候变化情景下的有效性，解决这一复杂的水-农业-营养关系挑战。它将让K-12学生参与与美国紧迫的水-食物-环境问题相关的外展活动，为本科生提供计算研究机会，并在多学科的界面上培养研究生。研究结果将通过同行评议的出版物、两所大学的推广活动和会议报告来传播。结果将与农民、水资源管理者和更广泛的MRB社区面临的关键问题相关。该项目的目标是(1)评估气候变化下东部湄公河流域扩大灌溉规模以维持粮食生产的必要性、潜力和可行性；(2)量化西部湄公河流域持续灌溉和未来气候下的水资源短缺；(3)评估合理的农业适应策略，以减轻整个湄公河流域的水资源压力；(4)量化绿色、蓝色、以及各种适应和气候变化情景下整个MRB的灰水足迹。该项目将使用基于社区土地模型第5版（CLM5）的全新综合水文-农业-生态建模框架，能够在大范围内模拟地表水、地下水、作物生长、农业管理、灌溉、水库运行和养分流动过程。该框架将为研究气候变化下水、农业和营养系统的共同演变提供新的能力，并以相对高的分辨率在大范围内评估替代的水和作物管理实践。该研究将利用全面考虑水资源可持续性和全流域灰水足迹的气候变化适应措施，为东部和西部不同的MRB农业生态系统的可持续农业集约化提供新的知识。这种新型的系统建模方法将有助于推动自然与人类耦合系统的研究走向下一代地球系统科学。该奖项由环境可持续性和水文科学项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.