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

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.