Utility of a GIS in watershed management. A case study

A geographic information system data base was established for a small watershed in Shelby County, Tennessee, for both surface and subsurface water attributes. The surface water portion of the GIS was used to predict and illustrate the flood prone areas of the watershed for various levels of flood frequency. Flood elevations determined from accepted rainfall/runoff relationships were entered electronically into the GIS with the predicted elevations shown as flood prone areas. The system represents a tool for the evaluation of the impact of runoff changes due to development in a watershed on the exiting hydraulic conveyance structures and provides the engineer the capability of illustrating the changes to decision makers. The subsurface complement consisted of establishing a data base containing both subsurface (water and geological) characteristics and those surface characteristics which influence groundwater quality and/or quantity. Having such data in a common system permitted the analysis of contamination potential from surface activities for the Memphis water system. The combination of the surface and subsurface GIS data bases would permit total watershed management to include both surface water runoff as well as the movement of part of the surface water into the subsurface system