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

阿根廷的潘帕斯草原，这个项目的目标地区，有一个非常平坦的浮雕，只有在地球上的其他几个地方发现，例如美国中西部或中欧的部分地区。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。地下水接近地表，与地表水和气候密切相关，根据其深度，可能对自然和人类系统产生积极或消极的影响。例如，浅层地下水可以提供有用的备份，在降水量低时稳定作物产量，但如果它到达地表，也可能引发大规模洪水事件。相反，土地使用（例如，作物与牧场）可对地下水的数量和质量产生重大影响，因为植被通过蒸散和排水影响地下水的补给。该项目正在组装一个链接的建模框架，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，湿期或干期），以及个人和土地使用决策。该框架结合了（一）基于物理的水文模型，（二）生物物理作物生长模型和（三）基于代理的土地利用决策和农业生产模型。链接模型用于探索决策的结果（例如，土地分配），通过将地下水的深度保持在理想的限度内，平衡经济和农艺考虑（利润、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做出的。 目前，用于生产粮食的水超过了所有其他用途。在今后几十年中，气候多变性和变化将对农业用水和需求构成严重挑战，从而对全球粮食安全构成严重挑战。在平坦的潘帕斯草原，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一个独特的机会。为了处理在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战略如何在各种气候和社会经济情景下发挥作用的方法。重点是找到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。通过探索在多种可能的未来下的战略成果，利益攸关方可以确定脆弱性，并设计适应机制来科普变化。平原地区浅层地下水复杂的双向动力学提出了另一个有趣的社会科学问题：农民面临的洪水和干旱风险不仅受到他或她自己的决定的影响，还受到附近其他人的影响。这所谓的？相互依存的安全？这一问题需要邻近农民采取协调行动，管理地下水位和相关风险。本项目将解决了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.