Introduction
HEC-ResSIM, first released in 2002 as the successor to HEC-5, models reservoir operations at one or more
reservoirs (both small and large scale) based on operational goals and constraints. HEC-ResSim contains three
separate modules: watershed, reservoir and simulation. Through the watershed setup module, the user builds
stream alignments, diversions, draws the location of reservoirs, levees, diversions, and off storage areas, and
sets computation points. Stream alignments then create stream elements, nodes, and junctions. Through the
reservoir module, the user may build the network schematic and describe the physical and operations elements of
the reservoir, including adding routing reaches and alternative scenarios for analysis. The simulation module
configures the simulation and reviews results. Computational points are common points at which the modules
exchange data. The model is able to simulate single events or events over a period of time. HEC-ResSIM has been
applied to simulate reservoir operations for flood management, low flows augmentation, water supply for planning
studies, detailed reservoir regulation plan investigations, and real time decision support for reservoir
operators.HEC-ResSIM’s key feature is a common data storage system DSS with other HEC models. The program allows
for advance programming rules using Phython scripting. HEC-ResSim was developed by the Hydrologic Engineering
Center of the United States Corp of Engineer and is currently supported only on the Microsoft Windows operating
system.
