Mississippi Facts
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Mississippi is 4000 km long.
Mississippi is the 4th longest river in the World.
Flows through ten states.
Its drainage basin covers 40% of the USA.
Mississippi is used to transport many agricultural and industrial goods.
Mississippi Flooding
 Mississippi floods regularly creating fertile flood plain.
 Natural levees bank the river acting as natural flood barriers, except in
very wet periods.
 In 1973 a major flood event occurred.
Flood Management on the Mississippi
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300 + dams control the water.
Levees have been increased in places.
New levees built to prevent river spilling onto the floodplain.
Storage reservoirs created to store excess water.
Dykes created to control flow of river.
Sections of the river straightened by cutting through meanders.
River lined with concrete slabs to slow erosion.
For twenty years these worked until 1993!!
1993 Flood Event
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May & April heavy rain saturated the ground.
June & July caused flash floods.
Mid July River reached so high levees began to collapse.
30 million sandbags used.
Effects:
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48 killed.
Floodwater covered an area size of British Isles.
70 000 Evacuated.
$2 billion worth of crops destroyed.
River closed to traffic for two months.
Towns left abandoned.
Reasons for floods damage?
 Shortening the river made it flow quicker causing more erosion of the
levees.
 Speeding up the river flow increased pressure on river banks.
 Changing the flow of the river caused the worse floods ever even though
water was less than previous floods.