Urban Growth Impacts on Surface Hydrology in Mid-Atlantic and New England Watersheds

Principal Investigator:

Stephen D. Prince, Scott Goetz (WHRC)

Despite a great deal of effort, much of the progress that has been made in restoring the health of the nation’s waterways has been offset by continued urban, suburban, and exurban development. The expansion of impervious surface areas (the built environment, such as roads, houses, etc) associated with this urban growth disrupts the hydrology and ecology of waterways by inhibiting infiltration, increasing peak flows, reducing base flows, reducing lag time between storm events and peak discharge (i.e., increased flashiness), facilitating the overland transport of pollutants, and increasing sediment loads associated with stream channel incision and erosion. Other impacts result from the associated loss of resource lands (forests, wetlands, agriculture and riparian buffer areas), which serve ecological functions such as filtering water flows and buffering chemical pollutants.

Many of the pollutants arise from impervious surface areas, particularly the roads and parking lots built to accommodate increased vehicle use. The adverse effects of these changes can be mitigated by increased vegetation cover, landscape configuration, and low-impact development techniques, which together reduce the volume and velocity of overland flows, uptake excess nutrients, maintain stream bank integrity, provide shade that reduces stream warming, and generally reduce the negative ecological and economic impacts of urbanization.

The aim of this project is to advance the understanding of the impacts of land cover, land use and land use change on discharge behavior of watersheds. The relationships of runoff to land cover have long been known, but have only been documented for small watersheds and not for large regions such as the 164,000km2 Chesapeake Bay watershed.

The necessary data sets for Chesapeake Bay watershed are available as are the parameters needed for the application of runoff models through our collaborators at EPA’s Chesapeake Bay Program and our participation in the Chesapeake Community Modeling Program (CCMP), which includes a wide variety of hydrological modeling programs that are active in the region. A number of appropriate hydrological runoff models will be applied to the region in order the translate the current and future projections of land cover of the region into estimates of runoff, nutrient transport into the Chesapeake and other adverse effects of urbanization for the very large region that constitutes the Chesapeake Bay watershed.