USACE CWMS - Yazoo Watershed

The Corps Water Management System (CWMS) includes four interrelated models to assist with water management for the basin:
- GeoHMS (Geospatial Hydrologic Modeling Extension)
- ResSIM (Reservoir System Simulation)
- RAS (River Analysis System)
- FIA (Flood Impact Analysis)

The Yazoo Basin is located in central and western Mississippi, encompassing approximately 13,500 square miles of drainage area (30% of the total area of the state of Mississippi). The authorized purpose of the four basin lakes is flood control. Other benefits are derived from the operation of the reservoirs, such as recreation, improved fish and wildlife habitat, and incidental navigation. The Flood Control Act of 15 June 1936 authorized the construction of the reservoirs within the Yazoo Basin. Construction began in the 1940’s and lasted through the 1950’s. All reservoirs were in operation by 1954.
There are two main topographic sections in the basin: the hill section and the delta section. The hill section above the lakes is fan shaped and is a rolling to hilly region with moderate variations on elevations. Soils in the uplands are composed chiefly of clays and loams and are moderately productive but subject to severe erosion. Alluvial soils in the stream valleys are fertile and generally cleared for cultivation. Vegetation in the hill section is characterized by hardwoods. The delta section is very flat and consists mainly of agricultural land.