Impervious surface from development causes flooding

Could similar development in the Suwannee River watershed have something to do with the 700-year floods in 2009 and 2013?

Georgia State University, PR, December 6, 2017 Researchers Find Urban Development Dramatically Increases Stream Flow,

Fig. 1 watersheds

…Between 1992 and 2011, the amount of developed land in these watersheds also doubled, almost entirely at the expense of forest land.

In both watersheds, this urbanization led to a 26 percent increase in annual stream flow from 1986 to 2010, as well as a doubling of high-flow days.

“This means that during a storm event, you’ll now see more runoff, more extreme flows and more flooding than you would have seen for a similar storm event in 1986,” said Jeremy Diem, the study’s lead author and associate professor in the Department of Geosciences at Georgia State.

Here’s the actual paper, Diverse multi-decadal changes in streamflow within a rapidly urbanizing region, Jeremy E. Diem, T. Chee Hill, Richard A. Milligan, Journal of Hydrology, Volume 556, January 2018, Pages 61-71,

Owed to Flint Riverkeeper Gordon Rogers, who has been saying for years there were no 700-year rains during those floods.

This problem is fixable, even for developments that went in before current codes that require detention ponds and the like, by adding ponds, trees, and other changes afterwards. Funding can be an issue.

For example, Valdosta has now spent upwards of $60 million on its new Withlacoochee Wastewater Treatment Plant, force main, and other improvements. It could be a lot less expensive to plan ahead.

 -jsq, John S. Quarterman, Suwannee RIVERKEEPER®

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