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
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 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
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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