Mississippi Feature

Flood!

The Mississippi river system is the third longest river system in the world, draining 41% of the continental United States. That's an awful lot of water, especially when the river floods!

The Mississippi River flood of 1993 was the most devastating flooding disaster in U.S. history. Seventeen thousand square miles of land were covered by flood waters in a region covering all or parts of nine states (North Dakota, South Dakota, Nebraska, Kansas, Missouri, Iowa, Wisconsin, Minnesota, Illinois). The chances of a flood that large are one in one hundred in any given year, which is why it is called a hundred year flood.

Before humans moved in and populated the area, the Mississippi River, like all rivers, was free to meander throughout its flood plain, overflow its banks seasonally, and there was nothing to stop it. The Mississippi River is now one of the most heavily engineered natural features in the U.S.

The character of the river and the flood plain has changed because of agriculture and urbanization. Approximately 80% of the original wetlands along the river have been drained since the 1940's. Wetlands in their natural state act as storage reservoirs for flood waters. They absorb water during heavy rains and release it slowly. The gradual release of flood water run-off to streams reduces flood volumes. The river channel itself has been artificially managed and constrained by levees and flood walls. These structures increase the volume of water that can be held in the channel, which can increase the size of the flooded area if the levee breaks.

Nearly fifty people died as a result of the flooding in 1993, 26,000 were evacuated and over 56,000 homes were damaged. Economic losses caused by the flooding totaled $10-12 billion. Indirect losses in the form of lost wages and production can't be accurately calculated. Des Moines, Iowa, located in the center of the flood region, became the largest U.S. city to lose its water supply when its water treatment plant flooded. More than 250,000 people lost drinking water for 19 hot summer days. The flooding submerged eight million acres of farmland. Barge traffic was halted for two months; carriers lost an estimated $1 million per day. Flooding is estimated to have cost $500 million in road damage. Twenty percent of the people who suffered some sort of economic or personal loss in the 1993 flood have moved out of the flood plain.

On one hand, this type of flooding is a natural occurrence, and without it, the river ecosystem would fail. The river needs to reclaim nutrients in the form of vegetable matter and such, and deposit it in the form of the silt that flooding leaves behind. Some plants and animals can only grow or spawn during high flood times. On the other hand, floods mean crop and property losses. And loss of life.

The Mississippi isn't the only river that floods. Rivers around the country, and the world, flood regularly, and every flood leaves human tragedy in its wake. So, why do people continue to live in flood plains? Family history, a connection to the land, the fact that bad flooding events are rare, all combine to keep people where they are. If there was a chance a major disaster like this would hit your home, especially if it just had, would you leave?

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