July 1 – Without A Paddle

Today’s factismal: The Great Mississippi Flood of 1927 covered an area larger than West Virginia

The mighty Mississippi is famous in song and story, and for good reason. At 2,340 miles long, it is the second longest river in the USA. With a drainage area of 1,150,000 sq mi, it covers nearly 40% of the USA. And with an average discharge of 593,000 cu ft/s, it moves enough water to completely cover Louisiana to a depth of ten feet in just one year!

A ferry crosses the Mississippi River in New Orleans (My camera)

A ferry crosses the Mississippi River in New Orleans
(My camera)

Of course, that drainage is all well and good when it works. But sometimes it fails and the water comes in faster than it can drain away. When that happens, we get a flood. And the worst flood in US history happened in 1927 when a series of strong rainstorms lingered through summer and into fall and winter. Every day, the Mississippi’s level rose more and people got more worried. On Christmas Day, the river finally over-topped its banks and the levees that had been put into place to prevent flooding. That quickly led to catastrophic flooding with the river breaking through the levee in more than 45 places. Before it was over, more than 27,000 sq mi of land would be flooded – an area the size of West Virginia!

The area covered by the Great Mississippi Flood of 1927 (Courtesy US Archives)

The area covered by the Great Mississippi Flood of 1927
(Courtesy US Archives)

The flood did more than $400 million in damage ($5.230 billion in 2013 dollars) and killed 246 people. It also changed the way that we treated the river. Up until that point, the belief had been that we could control flooding by constructing bigger and stronger levees; the Great Flood of 1927 showed that the effects were worse when those levees broke than it would have been if the levees had never been built. As a result, today the US Army Corps of Engineers and local flood agencies work to divert flood waters into temporary catchments and alternate rivers. Though this hasn’t prevented the Mississippi from flooding, it has reduced the damage done when it does flood.

Of course, the Mississippi isn’t the only river that floods. And naturally, there’s an app for that. Called FloCast (Flood Observations – Citizens As Scientists using Technology Project), the app was designed by the University of Okjlahoma to let you provide information on local stream conditions to scientists who are trying to discover where the next great flood will happen – and stop it.

2 thoughts on “July 1 – Without A Paddle

  1. Pingback: July 30 – Zoned Out – Little facts about science

  2. Pingback: February 2 – Lord Love A Duck | Little facts about science

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