1998 Impervious Surface Data

Land Use/Land Cover and Impervious Surface

Land Use map of a portion of Coffee County, Al. with impervious surface.

Process Documentation

Despite the recognition of the environmental impacts of impervious surface area (ISA), few areas have ISA maps due in part to the technical challenges and cost constraints of using high spatial resolution (~ one meter) data for direct mapping of constructed surfaces. As an alternative, we have used existing national coverage data sources to model the percent cover of ISA on a one kilometer grid for the conterminous USA. The data sources included satellite observed nighttime lights, Landsat derived land cover, and U.S. Census Bureau road vectors. The ISA model was calibrated using eighty aerial photographs selected on urban-to-rural transects from thirteen cities in the USA. The product has values ranging from 0 to 100, indicating the percent cover of man made impervious surface. This product is the result of research funded by NASA's Land Cover Land Use Change Program.

The land cover data sets are single band raster images. All data are projected to Albers Conical Equal Area using the NAD83 Datum, GRS 1980 Spheroid with spatial resolution of 1,000 m x 1,000 m.

Source: NOAA-NESDIS National Geophysical Data Center

Values for impervious surfaces were assigned values ranging from 0-100 where 100 means that the area is 100% impervious to water.  Since these values were computed based upon light emitting from artificial sources at night, impervious surfaces due to rock are not indicated.

In the case illustrated to the right, the impervious surfaces are associated with an urban development while pervious surfaces are indicated by agricultural and forested land use.