The Katy Prairie Conservancy (now the Coastal Prairie Conservancy) has preserved prairies for more than 25 years to slow down and reduce floodwaters.

Tall-grass prairies and wetlands soak up, store and slow runoff from heavy rains, all of which decrease flooding for residents downstream.

But how does that work in practice in specific locations? How MUCH do nature-based initiatives reduce flooding? And how can they complement traditional engineered solutions?

Multifaceted Plan Could Hold Back Harvey’s Excess Floodwater

Working with the SSPEED Center at Rice University, the Conservancy produced this brochure. It outlines a plan to expand currently protected lands to 50,000 acres and restore 21,000 of those.

The plan would absorb, slow, and store water in the Upper Cypress Creek Watershed. It also recommends detaining water near Cypress Creek by creating shallow detention on private lands with the help of willing landowners.

Likewise, by constructing retention and detention ponds in the Upper Addicks Watershed, even more floodwater could be stored and slowed down. The plan also includes the creation of retention corridors along Bear and South Mayde creeks. The retention corridors would serve as a buffer for floodwaters that threaten communities along the creeks. These projects will store up to 110,000 acre-feet of floodwater.

That’s the equivalent of a foot of rain falling over 172 square miles! And that’s 10% of Harris County!

Expand Addicks Reservoir Storage through Excavation

Addicks and Barker Reservoirs are valuable assets that need to be restored and enhanced. Storing additional floodwaters in Addicks Reservoir can keep homes upstream safe and prevent extreme releases that destroy downstream properties, according to the Conservancy and SSPEED.

Put all these solutions together and the results look like the bar graph above.

The recommendations could easily hold back more water than Addicks had to release during Harvey.

Benefits Extend to Multiple Watersheds

During Harvey, so much water accumulated in the Cypress Creek watershed that it overflowed into the Addicks watershed. So, these recommendations could help reduce flood risk in superstorms along multiple streams, including Buffalo Bayou and Cypress Creek.

Other Interesting Statistics

The brochure also cites interesting statistics from other groups that touch on the plan. For instance, the Natural Resources Defense Council estimates that every 1% increase in soil organic matter results in the soil holding an additional 20,000 gallons of water per acre.

No One Solution

After studying flood reduction for almost five years now, I’ve concluded there is no silver bullet. No one solution will work for all situations. But every little bit helps. Multifaceted recommendations like these can ultimately reduce costs and increase effectiveness by harnessing the power of nature.

Natural solutions also provide numerous other benefits such as recreation and wildlife habitat.

Posted by Bob Rehak on 5/16/2022

1721 Days since Hurricane Harvey