CNH: From Farm Management to Governance of Landscapes: Climate, Water, and Land-Use Decisions in the Argentine Pampas

阿根廷潘帕斯草原，这个项目的目标地区，有一个极其平坦的地形，只有在地球上其他地方才有，比如美国中西部和中欧的部分地区。在这些平坦的平原上，气候、土壤水分和土地利用之间存在着强烈的双向耦合。地下水靠近地表，与地表水和气候密切相关，并根据其深度对自然和人类系统产生积极或消极的影响。例如，在降水少的时候，浅层地下水可以提供一个有用的后备，稳定作物产量，但如果它到达地面，也可能引发大规模的洪水事件。相反，土地利用（例如，作物与牧场）可以对地下水的数量和质量产生强烈影响，因为植被通过蒸发蒸腾和排水影响地下水补给。该项目正在组装一个相互关联的建模框架，以探索地表水和地下水之间的相互作用、合理的气候情景（例如，湿润期或干旱期）以及个人和土地利用决策。该框架结合了(i)基于物理的水文模型，（ii）生物物理作物生长模型和（iii）基于主体的土地利用决策和农业生产模型。相关模型用于探索决策（例如土地分配）的结果，这些决策通过将地下水深度保持在理想范围内来平衡经济和农学考虑（利润、作物轮作）与洪水和干旱风险的管理；这些决定是在未来气候不确定的背景下作出的。目前，用于生产粮食的水超过了所有其他用途。未来几十年，气候变率和变化将对农业用水和用水需求构成严重挑战，从而对全球粮食安全构成严重挑战。潘帕斯平原的气候、土地利用和土壤水分之间的紧密耦合为研究水文和生态系统过程之间的反馈以及这些过程如何受到人类决策的影响提供了独特的机会。为了应对未来气候和社会经济条件不明确的情况下的决策，该项目探讨了评估多种风险管理策略在广泛的气候和社会经济情景下的表现的方法。重点是寻找在大多数未来条件下表现相对较好的策略，即使我们不确切知道这些未来会是什么。通过探索多种可能未来下的战略结果，利益相关者可以识别脆弱性并设计适应机制来应对变化。平原浅层地下水复杂的双向动态引发了另一个有趣的社会科学问题：农民面临的洪涝和干旱风险不仅受到他或她自己决策的影响，还受到附近其他人决策的影响。这就是所谓的？相互依赖的安全?这个问题需要邻近的农民采取协调行动来管理地下水位和相关风险。这个项目将解决理解在这种情况下鼓励非正式或正式合作的条件的挑战。

The Argentine Pampas, the region targeted by this project, has an extremely flat relief found only in few other places on Earth, for example parts of the U.S. Midwest or central Europe. In these flat plains, there is a strong, two-way coupling between climate, soil water, and land use. Groundwater is close to the surface, tightly associated with surface water and climate, and can have either positive or negative impacts on natural and human systems depending on its depth. For instance, shallow groundwater can provide a useful backup that stabilizes crop yields when precipitation is low, but also may trigger massive flooding events if it reaches the surface. Conversely, land use (e.g., crops vs. pastures) can have a strong effect on the quantity and quality of groundwater, as vegetation influences groundwater recharge through evapotranspiration and drainage. The project is assembling a linked modeling framework to explore the interactions between surface and ground water, plausible climate scenarios (e.g., wet or dry periods), and individual and land use decisions. This framework combines (i) a physically-based hydrological model, (ii) biophysical crop growth models and (iii) an agent-based model of land use decisions and farm production. The linked models are used to explore the outcomes of decisions (e.g., land allocation) that balance economic and agronomic considerations (profits, crop rotations) with management of flooding and drought risks by maintaining the depth of groundwater within desirable limits; these decisions are embedded in the context of uncertain future climate. Water to produce food currently exceeds all other uses. In the next decades, climate variability and change will pose serious challenges to water availability and demand in agriculture and, consequently, to global food security. The tight coupling between climate, land use, and soil water in the flat Pampas offers a unique opportunity to study feedbacks between hydrological and ecosystem processes, and how these are influenced by human decisions. To deal with decision-making under ambiguity in future climate and socio-economic conditions, the project explores approaches that assess how multiple risk management strategies perform over a wide range of climate and socio-economic scenarios. The emphasis is on finding strategies that will perform relatively well across most future conditions, even if we do not know precisely what those futures will be. By exploring the outcomes of strategies under multiple plausible futures, stakeholders can identify vulnerabilities and design adaptation mechanisms to cope with change. The complex two-way dynamics of shallow groundwater in flat plains set up another interesting social science problem: flood and drought risks faced by a farmer are influenced not only by his or her own decisions, but also by those of others nearby. This so-called ?interdependent security? problem requires coordinated action by neighboring farmers to manage groundwater levels and associated risks. This project will address the challenge of understanding the conditions that encourage informal or formal cooperation in such situations.