High-Resolution Image

Shown here are differences in impervious surface estimates between the national (DMSP-NLCD) and regional (Landsat ETM+) maps across the 168,000-square-kilometer Chesapeake Bay watershed. The regional map was aggregated to match the one-square-kilometer resolution of the national map.
In a paper published in 2005 Environmental Management, Woods Hole Senior Scientist Scott Goetz and University of California Santa Barbara doctoral student Patrick Jantz used DMSP and Landsat data to map changes in impervious cover in the Chesapeake Bay Watershed between the years 1990 and 2000 in order to determine the loss of forest and crop lands to expanding residential and commercial development. Goetz and colleagues, in a paper in the Journal of the American Water Resources Association, found that impervious cover impacted stream biology in hundreds of small watersheds.
In the same way that such regional maps inform Chesapeake Bay watershed restoration efforts, a similar national impervious cover map has utility for incorporating landscape configuration information into large-area hydrological models and for improving a range of watershed management efforts. Current maps of the built environment provide a baseline data set upon which ongoing regional and national mapping efforts can be developed to better inform environmental policy, particularly those related to human modification of the landscape that have multiple impacts on aquatic ecosystems and water quality.

Image contributed by Scott Goetz, Woods Hole Research Center, Falmouth, MA.