Five Flood Facts from the Army Corps of Engineers - KTIV News 4 Sioux City IA: News, Weather and Sports

Five Flood Facts from the Army Corps of Engineers


Five Flood Facts (IV)

A Focus on the 2011 Missouri River Basin Flood

The Flood Fight continues with water levels high, up and down the river. The U.S. Army Corps of Engineers, Missouri River Joint Information Center, continues to answer flood-related questions.

In an ongoing effort to help the public better understand the many aspects of this flooding, the following answers to commonly asked questions are provided.

This week, the topic addressed is the Missouri River System and the Corps responsibility along it.

What is the Master Manual?

The Master Manual is a water control plan that guides how much water should be released from the six reservoirs on the Missouri River Basin, when and for how long. The Master Manual hydrology (runoff volume, timing, shape of watersheds, etc.) is based on over 100 years of historical runoff records (1898-2004).

The Corps revised the Master Manual in 2004 following a 14-year period of public involvement to balance all the competing uses for the Missouri River and to serve all the purposes for which it was authorized and constructed. Input was derived from residents and farmers who live along the Missouri River, in addition to local, state and federal elected officials. Hundreds of alternatives were analyzed and considered during this process. In 2006, a secondary spring pulse revision was added.

Each fall, a draft annual operating plan is developed to provide stakeholders information on the expected results of the operation of the reservoir system for the coming year under widely varying water-supply conditions. The draft plan is also circulated in the fall, and public meetings are held through the Missouri River Basin to gain input from the public and tribes. Based on input received, the plan is finalized and released, generally in December.

Floodwise, for what is the Corps responsible?

In addition to the operation of the six Missouri River mainstem dams and reservoir system, the Omaha District has constructed nearly 582 miles of federal levees from Montana to Missouri including North Dakota, South Dakota, Wyoming, Colorado, Iowa and Nebraska (from Omaha to Rulo, in Nebraska).

The Corps conducts annual and more intensive five-year periodic inspections for levees within the Public Law 84-99 and its dams. Local levee sponsors are responsible for the operations, maintenance and monitoring of their levee systems. As soon as an issue is identified on one of the federal levees, the Corps immediately gets a team on site with the local sponsor to assess the situation. During this flood event, the Corps has multiple teams on the ground inspecting both sides of the Missouri River to support surveillance activities and provide technical assistance to levee sponsors.

What beyond flood control dictates the Corps operation of the Missouri River?

The Missouri River Mainstem Reservoir System is multiuse and is operated through the balancing of eight diverse, Congressionally-authorized purposes. Flood risk management is only one of these mandates. It directs that these reservoirs capture spring and summer runoff and allows the Corps to manage releases throughout the year in order to accommodate the other seven authorized purposes: navigation, irrigation, water supply, hydropower, fish and wildlife, recreation, and water quality.

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Who tells the Corps what to do?

The Corps is under the direction of U.S. Congress. The Flood Control Act of June 22, 1936 tasked the Corps with certain responsibilities regarding this type of natural disaster. Moreover, Public Law 93-288 authorizes the Federal Emergency Management Agency (FEMA) to task the Corps with disaster recovery missions under the Federal Response Plan.

What is in the immediate future for the river?

After this flood fight is over, the Corps will begin a post-flood assessment that will analyze how the system performed and how the system was managed.

2011 will be a new point in the history of the Missouri River Basin, both in terms of hydrology and flood plain impacts. The Corps will review the flooding this year to determine the flood's effects and learn where improvements or adjustments might be warranted. Whether future studies may lead to changes in the operation of the reservoir system is yet to be determined.

The Corps has not conducted any extensive investigations at any of the breached areas. As the river levels approach bankfull, we will be able to complete a more detailed assessment.

The process of erosion/scour is a function of water depth, velocity, sediment characteristics and sediment availability. The higher the flow velocities, the greater the potential for erosion/scour.

Areas that have not experienced erosion/scour for a number of years, or areas that have been traditionally depositional, may experience these effects and need to be checked.

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