Tag Archive for: Houston a Year After Harvey

Houston A Year After Harvey: Where We Are And Where We Need To Be

Jim Blackburn, JD, professor of environmental law at Rice and Phil Bedient, PhD., a professor of engineering also at Rice, have just released an important new study called Houston a Year After Harvey: Where We Are and Where We Need to Be . Because of the length, detail, intricate maps and charts, and file size, this is best viewed on something larger than a smartphone.

Written for the Average Adult

Three things immediately become apparent when reviewing this 55-page report. It’s wide ranging in scope. It’s an excellent work of scholarship. And it’s well written; the average adult should be able to understand all the key concepts without difficulty.

Houston A Year After Harvey: Three Major Sections

It’s an excellent summary of what happened during Harvey, how the community is responding, and what still needs to be done – major watershed by major watershed.

The Problems of Obsolete Flood Plain Maps

This paper is organized into three main sections. First, the issues of obsolete 100-year floodplain maps and increasing rainfall are discussed because they are key to fully understanding the current dilemma and shaping alternative concepts for long-term protection. Whether or not you believe in climate change, the case for revising flood maps is pretty compelling based on the math alone. We’ve had five so-called 500-year storms in the last 25 years. Are we just spectacularly unlucky? Or do we need to revisit the assumptions and underlying math?

USGS did this recently and designated Harvey a 42-year flood at the West Fork and Grand Parkway.

Any time you try to predict the frequency of rarely observed or unobserved events, such as 500-year storms, you venture way out on a limb. The data on which you base assumptions is thin. Worse, one of the fundamental precepts of extreme value analysis (EVA) is that nothing changes during the 500 years under analysis.

Good luck with that. Five hundred years ago, the U.S., Texas, Houston, developers, gasoline, F150s and sand mining didn’t even exist. As we get more data and update assumptions, flood maps are being redrawn. So are the guidelines which form the basis for different types of development. Instead of raising new homes two feet above the 100 year flood plain, officials are now talking about two feet above the 500-year flood plain.

Issues that Need to Be Addressed Watershed by Watershed

The second part of Houston A Year After Harvey is a geographic overview of the flood issues and potential responses to various watersheds across Harris County.

The discussion of the West Fork of the San Jacinto goes from pages 28-30. It starts with a discussion of sedimentation, where the sediment is coming from and why we need stronger regulation of sand mining.

In regard to sedimentation, the reports also discusses  the need for dredging to restore the river’s carrying capacity.

Finally, in regard to the San Jacinto, the report discusses the need to change the operating philosophy for the dams on Lake Conroe and Lake Houston to enable pre-release as a strategy for flood mitigation. This has already happened, they note, with the approval of the TCEQ to temporarily lower the level of Lake Conroe during the peak of hurricane season.

Different Solution Sets for Different Flooding Issues

The third major portion of Houston A Year After Harvey discusses different flood management concepts for three zones of the Houston area that have different flooding issues.

The authors break the county up into three major zones, A, B and C. A stretches from Addicks/Barker to the Katy Prairie. B covers the central part of the county. And C covers coastal areas.

The discussion of Zone B (which includes the Lake Houston and San Jacinto River) includes explanations for many of the projects listed on the Harris County Flood Control District Flood Bond that we are now voting on. See pages 42 through 45.

But don’t stop there. There’s also a great description for how the Ike Dike could work in Zone C.

How All the Pieces of the Flood Bond Fit Together

All in all, Houston A Year After Harvey makes a great case for the flood bond, without ever really setting out to do that. It will help give you a better understanding for how our drainage problems affect the people around us and vice versa.

The entire report is posted on this web site with permission of Rice University’s Baker Institute for Public Policy and SSPEED Center. ©2018 James A. Baker III Institute for Public Policy of Rice University. It will be permanently stored in the Reports Section under the Hurricane Harvey tab for easy future access.

Posted on August 13, 2018 by Bob Rehak

349 Days Since Hurricane Harvey