Hydrologic Modeling System (HMS), developed by the Hydrologic Engineering Center (HEC) of the United States Army Corps of Engineers, is computer software for simulation of precipitation-runoff processes. For modeling purposes, HMS requires the system to be subdivided into different elements properly attributed with the parameters that describe their operation. Setting up the hydrologic model and manual estimation of these parameters is a time-consuming and subjective procedure that can be automated using GIS. A set of raster and vector-based GIS tools for determination of hydrologic elements and their connectivity, calculation of their parameters, and preparation of an input file for HMS has been developed. These tools allow automated model setup that is faster and leads to reproducible results.