Understanding the links between humans, climate change, water and carbon and in a Corn Belt Watershed

Abstract:

Accounting for the value of ecosystem services is difficult for several reasons: we need to understand and model the behavior of humans, and how they respond to changes in policies, we need to quantify the changes in material fluxes or ecological responses resulting from their behavior, and finally we need to monetize the value of those material fluxes. Since coupled human-natural systems are highly idiosyncratic, integrated modeling can be challenging because it is not easy to transfer results from one system to another. Moreover, modeling changes in multiple ecosystem services often requires the simultaneous coordination of several biophysical models. In a non-static world, climate change models are also often necessary to identify future challenges and opportunities for better policy-making.

We will discuss results from an integrated modeling perspective for the Raccoon River watershed in central Iowa. The watershed is in the heart of the Corn Belt, and it is under very intensive agricultural production which results in nitrate levels so high that a Total Maximum Daily Load has been put in place. The Des Moines Water Works that provides water to Iowa’s capital either from the Raccoon or the Des Moines River has had to build several layers of treatment to ensure the water is safe to drink.

We will present results from the integration of an agent-based model with a surface water quality model (the Soil and Water Assessment Tool) and an edge of field environmental model (the Environmental Policy Integrated Climate). The integration can simultaneously provide changes in water quality indicators – particularly nitrates, which can be monetized using the avoided cost method – and carbon sequestration – for which monetary values are readily available in the literature. This integrated system is linked to regional climate change models to help assess changes in agricultural productivity and farmers’ behavior in the future.

We will discuss the importance of quantifying and monetizing as many services as possible in the context of conservation and agricultural policies that compensate farmers for more environmentally friendly agricultural practices such as the use of no till or the planting of perennial grasses. Monetizing ecosystem services allows for the direct comparison of the costs and benefits of these policies.