The U.S. Army Corps of Engineers (Corps) Missouri River Basin Water Management (MRBWM) office develops runoff volume forecasts for the purpose of meeting downstream flow targets to serve system purposes such as navigation, water supply and flood control.
Runoff forecasts for Mainstem System operations use data from the National Weather Service’s Missouri Basin River Forecast Center and Climate Prediction Center, the U.S. Geological Survey, the Natural Resources Conservation Service, State climate offices, and others.
Short-Range Runoff (Inflow) Projections: Day-to-day scheduling of releases is necessary to regulate the System on an integrated basis and requires the Corps to develop daily flow forecasts at key streamgaging locations throughout the basin. These forecasts are based on observed and anticipated precipitation, temperature, temperature-snowmelt relationships, rainfall-runoff relationships, observed streamflow in the main stem of the Missouri River and tributaries, previous precipitation and other factors that often may be subject to only qualitative analysis.
Lower Missouri River Streamflow Forecasting: Scheduling releases from Gavins Point during the open-water season (generally late March through mid-December) is based on downstream navigation target locations on the Missouri River at: Sioux City, IA; Omaha, NE; Nebraska City, NE; and Kansas City, MO. Of these four locations, Omaha, Nebraska City and Kansas City also serve as downstream flood control target locations. The Corps’ Missouri River Basin Water Management office schedules the mainstem project releases, including Gavins Point. Scheduling Gavins Point releases requires developing accurate forecasts of lower Missouri River reach inflows between Gavins Point, the lowermost System dam, and flow forecasts of at the four downstream target locations. These forecasts are developed daily and project 14 days in the future. They are compared to daily forecasts developed by the NWS's Missouri Basin River Forecast Center.
Monthly Reach Inflow (Runoff) Forecasts: The first week of each month, the MRBWM office prepares a monthly incremental inflow forecast for the six System reservoir reaches. These forecasts are based on, but not limited to: monthly average reach runoff, historical reach runoff, existing and previous soil moisture conditions, reach precipitation and/or river gage readings during March-April and May-July, observed reach temperature, accumulated snow over the incremental drainage area, long-term precipitation and temperature outlooks, and accumulated mountain snow water equivalent. Projected runoff calculations includes water in the system, in the soil, in mountain snow, and plains snow estimates and precipitation outlooks from the National Weather Service's Climate Prediction Center.