ADAPTATION OF LAND USE TO SURFICIAL GEOLOGY IN METROPOLITAN WASHINGTON, D. C

This study is concerned with environmental constraints on land-use development, specifically the extent to which land-use patterns in the Washington, D.C., metropolitan area have adapted to the geologic suitability of the underlying terrain. Implicit in the investigation is a process of communicating geologic information, and incorporating such information into land-use decisions.;The study found significant relationships among land uses and geologic map units, and significant differences in land-use and geologic suitability regimes in subregions based on distance from city center. More recently-developed areas near the urban core have higher proportional associations of residential and agricultural land use with appropriate surficial geologic characteristics than do the outlying areas on the metropolitan fringe. These results suggest that the recent availability of earth science information to land-use planning agencies has somewhat improved the allocation of changed land uses to geologically-suitable terrain.;In the study area as a whole, residential and agricultural land-use occurrences were found to be 67% and 56% adaptive, respectively, to corresponding surficial geologic terrain deemed most suitable for those uses. While these results constitute evidence that land-use patterns have evolved somewhat in accordance with a geologically-adaptive model, nevertheless major areas of residential and agricultural land uses are associated with geologically-unsuitable terrain, with the likely consequence that the region has borne increased costs over the years in establishing and maintaining such uses.;Land-use data were derived from high-altitude color infrared aerial photography, and the information on geologic suitability was obtained from a new U.S. Geological Survey map of landforms and surface materials compiled to aid non-geologists in land-use planning decisions. The new map was further interpreted and subdivided into those areas geologically suitable and unsuitable for residential and agricultural uses, respectively.