Residential development and stormwater runoff

This thesis describes an investigation of how local land use policies influence residential development and hydrologic impacts within lake watersheds. In particular we focused on how policies impact water resources by influencing human behavior. Many policies potentially alter economic returns that landowners gain from alternative land uses, and therefore lead to landscape changes in an indirect way that can be difficult to predict. Our primary objective was to develop and describe a method that links an economic model which simulates land use change to a hydrologic model which simulates surface water runoff. We demonstrated an application of this method by quantifying the effects of changing a zoning regulation, minimum lot size, on predicted residential development and stormwater runoff within lake watersheds in the city of Ellsworth, Maine, USA.

Our model results suggest that increasing minimum lot sizes in one watershed leads to decreases in future residential construction and stormwater runoff within that watershed. As a consequence we expect that density restrictions in the form of increased minimum lot sizes may help to lessen water resource impacts within a watershed, other things being equal. However, we also expect that residential construction may increase in neighboring watersheds to make up for the decreased housing supply in the restricted watershed. This suggests that policy makers should consider potential “spillover” effects related to policies that decrease housing supply within particular areas.

With this investigation we demonstrated one way in which our model can be used to gauge landscape and runoff impacts of alternative policies. In this application, we also quantified the spillover effects arising from decreased housing supply in a regulated watershed, highlighting the importance of regional planning in water resource management.