Mapping & Monitoring

Impervious Surfaces

Woods Hole Research Center scientists derived Bay-wide impervious surface area maps for the 1990 and 2000 time periods at unprecedented resolutions using our Landsat database together with high resolution Ikonos satellite imagery, GIS maps of local planimetrics, and regression tree classifiers. In the case of the regression trees, a continuous variable is output (e.g. proportion of each pixel that is impervious), rather than categorical classes as with the land cover type mapping.

The impervious surface maps are at a fine resolution (30m), but, importantly, each cell provides sub-pixel information on the proportion (0-100%) of the 900 m2 area that is occupied by impervious surface features. These maps therefore represent a continuum of imperviousness across the entire Bay watershed. Validation of these maps is ongoing, but initial results using several different approaches suggest high accuracies, with an overall RMS error of just 2.7% for area means ranging from 0% to more than 40% imperviousness.

Access these data here:

ftp://ftp.whrc.org/GIS-RS/cbw/isa

This image shows the impervious surface map for 2000 for the Chesapeake Bay watershed. The images below show detailed maps for the areas labeled here.

 

Scranton Harrisburg
Scranton-Wilkes Barre, PA Harrisburg, PA
   
DC Richmond
Washington, DC Richmond, VA