Drainage basin case study

Alex and Lucy

Background to drainage basin

• Precipitation

• Interception – lack of vegetation cover

• Gradient

• Permeability of the surrounding area

• Small area of drainage basin

The Mississippi River Flood of 2008

Where?

•Second longest river system in the United States.

•2,340 miles (3,766 kilometers)

•Source in north-western Minnesota, Mouth in the Gulf of Mexico

•East of United States, to the Rocky Mountains

When?

• Spring 2008 – Heavy Rain Begins

• June 4th- Indiana

• June 7th – Wisconsin (Tornadoes)

• June 9th- Iowa

• June 10th – Illinois

• June 14th – Michigan

• June 27th- Missouri

What? How? • Rain, For example 10 inches in Wisconsin

• During the course of the first half of June, 2008, much of the Midwestern U.S. received copious amounts of rainfall as one storm system after another traversed the region.

• •Stations reported values ranging from 6 to 10 inches (150 to 250 mm) for the day across parts of the state.

• •3 miles east of Center Point, IN with 9.5 inches (241 mm), an unofficial report in Edinburgh, IN indicated that 10.71 inches (272 mm) fell on June 7th, which one might expect to see less frequently than once every 1000 years.

• •June rainfall totals exceeded 12 inches (305 mm) across large portions of the region, with Martinsville, IN reporting a total of 20.11 inches (511 mm) of rain for the month

Hydrograph

Primary Effects

• As of June 25, 83 of Iowa's 99 counties were declared disaster areas by Governor Chet Culver.

Secondary Effects

• One third of total US Corn crop and 30% of the total US Soya bean crop

• American Farm Bureau federation estimates that crop loses will exceed $8 billion dollars.

• The Iowa Renewable Fuels Association indicated that some 300 million gallons of the state's 2.2 billion gallons of biofuel refineries were still offline by the end of June due to flooding.

Comparisons to 1993 Flood

Avoidance of Flooding

• Not caused by humans, not really avoidable, but….

• Increase the vegetation density in the drainage basin

• Widening the river to increase flow rate

• Not build on flood Plaines – decrease the affects of flooding

• Lengthen the river