Although hydraulic analysis can benefit from digital terrain models and other GIS data sets, the complexity and unfamiliarity of GIS programs deters hydraulic engineers from using them. In developing HEC-GeoRAS, the Hydrologic Engineering Center has linked ARC/INFO's data development and display capabilities to HEC-RAS's hydraulic analysis capabilities. GeoRAS allows an engineer with little GIS training to use ARC/INFO to develop geometric data for import in HEC-RAS and view exported water surface profile data. The GeoRAS interface provides specific and logical access to ARC/INFO, allowing the engineer to concentrate in hydraulic principles, rather than GIS mechanics, during model development and analysis.