The Hydrologic Modeling System (HMS) is a windows based program being developed at the U.S. Army Corps of Engineers Hydrologic Engineering Center to replace HEC-1. An ArcView based pre-processing system called HECPREPRO v. 2.0 was recently developed for HMS. This pre-processing system creates an input basin file for HMS starting from basic GIS data (primarily a digital elevation model). The basin file created by this system provides enough information for HMS to automatically build a model schematic and add selected transform and routing attributes to basins and reaches in this schematic. This system uses Avenue programs created in several previous research projects carried out at the Center for Research in Water Resources and at ESRI. Therefore, the efforts of several individuals have contributed to its development. The following links provide more information about HECPREPRO v. 2.0 and related programs.