On August 25, Harris County residents will vote on a historic flood bond proposal. Everyone asks, “Will the bond include projects that help this area?”
That of course, raises the question, “What does the Lake Houston Area need?”
We Must Address Root Causes of Flooding HERE
Several factors make flooding here different from other parts of the region. Since Harvey, I’ve corresponded almost daily with experts in geology, hydrology, sedimentation, meteorology, city planning, engineering, mining, and disaster relief. The goal: to identify root causes of flooding in THIS area. They fall into three main “buckets”:
- Sedimentation. Sand and silt clog the San Jacinto everywhere. The Army Corps’ emergency dredging project will remove only part of the sand from a 2.1 mile stretch of the West Fork, and not even touch the East Fork. One of the largest blockages at the mouth of the West Fork will remain. And the Corps will only restore the areas it dredges to pre-Harvey conditions, not pre-1994 conditions.
- Releases from the dam at Lake Conroe can increase the volume of water flowing between Humble and Kingwood by ONE-THIRD. Of the roughly 240,000 cubic feet per second flowing down the west fork, 80,000 cubic feet of water per second came from the Lake Conroe dam. Many Lake Houston area residents say the onset of flooding coincided with release from Lake Conroe.
- We have a bottleneck at Lake Houston. In a flood, much more water converges on Lake Houston than Lake Conroe. At the peak of Harvey, Lake Houston took in 492,000 cubic feet per second whileLake Conroe took in only 130,000 CFS. Seven different watersheds converge on Lake Houston. Yet until water reaches the spillway of the dam, our floodgates have one-tenth the discharge capacity of Lake Conroe’s. This effectively eliminates pre-release as a mitigation strategy.
We Need Specific Solutions, Not Generic
True solutions to flooding in the Lake Houston area must address these unique challenges. Generic solutions, such as buyouts with bond money will help, but won’t affect many people. Pushing new development further away from rivers will help, but will not restore the carrying capacity of the San Jacinto, increase the discharge rate of the Lake Houston dam, or offset discharges from Lake Conroe.
We Need: Dredging, Detention, More Gates
The objective of the Lake Houston Area’s flood mitigation efforts should be, in my opinion and the opinion of many engineers, to restore our drainage systems to their original design capacity. Homes located outside of the 1% (100-year) risk area should not flood until we get a 1% flood. The same goes for the .02% level (500-year flood).
Experts generally focus on three categories of solutions that will help achieve those objectives: dredging, detention and greater discharge capacity for the dam, i.e., adding more gates. We need all three. No one solution will do the job by itself.
Additional DREDGING can remove sediment, restore carrying capacity, eliminate water backing up, and get us back to level of the original design assumptions.
Additional DETENTION on the West Fork will help offset discharges from the Lake Conroe dam, which affected the heavily populated area between Humble and Kingwood, where the worst and most damage took place.
Additional GATES on Lake Houston will help relieve the bottleneck created by the different discharge rates between Lake Conroe and Lake Houston.
Here’s a diagram that shows what we need in the flood bond, where we need it, and why.
Of the three types of projects, dredging is the easiest and fastest to implement. It can buy us time while we build additional dams and gates. That could take years.
More Explanation to Follow
I will elaborate on each of these in coming days.
Harris County Commissioners and executives from the Flood Control District will hold a meeting in Kingwood on July 10 to solicit input from the community on the flood bond.
Hopefully, this series of posts will help focus discussion on the things that will do the most good for the largest number of people at the lowest cost.
Mark Your Calendars for July 10
In the meantime, mark your calendars for July 10. The County wants your input. Get your friends and neighbors to do the same. If you want peace of mind, we need to restore our ditches, rivers, and drainage systems to their original design capacity.
The location of the bond meeting may change because of the expected turnout and need for parking. So check back often.
Posted June 26, 2018, by Bob Rehak, 14 days before the flood bond meeting and…
301 days since Hurricane Harvey.