Mississippi Floods, 1993.

When and Where The summer of 1993 Mississippi River, USA –

The summer of 1993

Mississippi River, USA –

Scale Image is 185 km across, north is in the top left corner.

Image is 185 km across, north is in the top left corner.

Causes of the flooding: Higher than normal rainfall during first half of 1993. Individual storms frequently dumped large volumes of precipitation that could not be accommodated by local streams. The ground was saturated because of cooler than normal conditions during the previous year. The river system had been altered over the previous century by the draining of wetlands and the construction of levees.

Causes of the flooding:

Higher than normal rainfall during first half of 1993.

Individual storms frequently dumped large volumes of precipitation that could not be accommodated by local streams.

The ground was saturated because of cooler than normal conditions during the previous year.

The river system had been altered over the previous century by the draining of wetlands and the construction of levees.

Agricultural and Residential Damage

Commercial Damage and Other Effects 150 levees collapsed under the pressure of the water. Dams burst. Bridges closed. 48 people killed. 70,000 people evacuated from their homes. Final damage cost estimated at $10 billion. Over 25% of the crops were lost.

150 levees collapsed under the pressure of the water.

Dams burst.

Bridges closed.

48 people killed.

70,000 people evacuated from their homes.

Final damage cost estimated at $10 billion.

Over 25% of the crops were lost.

Urban

Rural

Communication

Residential

Community Action

Flood Protection

Clean Up

Mud

Hose Down

Drinking Water

Homeless

Failed Crops

Valmeyer, Illinois

Modification of the Mississippi: 80% of wetlands drained since 1940’s River channel constrained by levees and floodwalls. Levees had not been built high enough to cope with this level of flood (a 1 in 100 year event). Reservoirs had been built on the tributaries to store floodwater but not on main river as it would halt transportation. Channelisation – deepening, widening, straightening, lining.

Modification of the Mississippi:

80% of wetlands drained since 1940’s

River channel constrained by levees and floodwalls.

Levees had not been built high enough to cope with this level of flood (a 1 in 100 year event).

Reservoirs had been built on the tributaries to store floodwater but not on main river as it would halt transportation.

Channelisation – deepening, widening, straightening, lining.

Human Impacts

River Engineering