USING GIS TO DEVELOP A NEW PHYSIOGRAPHIC MAP OF KENTUCKY

A new physiographic map of Kentucky has been developed using quantitative digital data to produce geographically referenced boundaries, rather than simply diagrammatic outlines. Physiography is the regional description of topography and landforms. If landforms can be defined by their patterns of slope and relief, these data, derived from digital elevation data sets, can be used to delineate physiographic regions. This method should allow more reliable identification of relevant physiographic regions for users. Previous physiographic maps for Kentucky were page-size graphic illustrations, and relied upon the authors' knowledge of major landform changes, bedrock geology, and land-use patterns to distinguish and characterize the different regions and subregions. When the various maps were digitized, the result was poorly documented digital themes with inaccurate geospatial references. With increasing use of GIS and other digital data technology, a properly georeferenced and well-constructed physiographic map can benefit numerous end users.

The new map was constructed by comparing several digital data sets available at the Kentucky Geological Survey (KGS). Slope and relief (local topographic range) maps were derived from U.S. Geological Survey digital elevation models (100-meter resolution). Initial physiographic boundaries were manually drawn to delineate areas according to slope and relief pattern. These boundaries were then reevaluated and revised using KGS digital geologic maps (1:500,000 scale) and U.S. Department of Agriculture soil-association maps (1:250,000 scale). Specific topographic expressions from USGS digital raster graphic files (1:100,000 scale) were checked for the final placement of selected boundaries.

The new physiographic map serves as a general tool for delineation of areas with similar landforms, slope patterns, bedrock, and soils. This can help biologists, archaeologists, soil scientists, geomorphologists, land-use planners, historians, and others studying or working with surface materials or landforms make better decisions. The new map will be available in both digital and traditional paper versions.