HEC-RAS (Hydrologic Engineering Centers River Analysis System) is a computer program that models the hydraulics of water flow through natural rivers and other channels.ĭEVELOPER :Hydrologic Engineering CenterHEC-RAS is designed to perform one-dimensional hydraulic calculations for a full network of natural and constructed channels. Hydrologic Engineering CenterThe Hydrologic Modeling System (HEC-HMS) is designed to simulate the complete hydrologic processes of dendritic watershed systems.