The effects of 2011 Ohio and Mississippi river valley flooding on Cairo, Illinois, area

Excerpt

In April 2011, the Ohio River began flooding farmland and cities from Pennsylvania to Illinois that were not protected by levees. The US Army Corps of Engineers (USACE) had realized as early as March that the torrential rains and heavy snow melt across the Upper Midwest were setting up the Mississippi River Basin for an epic flood year (USACE 2011). By late April, lakes and reservoirs along the Wabash and Ohio rivers were filled to capacity and cities without levees, such as Metropolis, Illinois, had lower sections covered by floodwaters. Cairo, Illinois, and many of the cities on the lower Mississippi River were protected by levees.

The levee is a massive earth works designed to contain floodwater. It has a flat crown at least 2.4 m (8 ft) wide with 3:1 sloped sides (a levee 9.1 m [30 ft] high would be at least 57.3 m [188 ft] wide, including 2.4 m [8 ft] wide crown plus two sides, each 27.4 m [90 ft] wide). The height of the levee changes the force of the river; a levee as high as a three- or four-story building can explode with the same power and suddenness of a dam bursting. The greatest…