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Greater Houston Flood Mitigation Consortium

More on flood tunnels

They’re a thing, I swear.

Japanese flood tunnel

While it’s far from clear whether it will ever happen, the concept almost immediately generated widespread response when it was announced earlier this spring. Local officials told the Houston Chronicle it’s outside-the-box thinking with benefits that could outweigh the heavy price tag. Residents reading about the project on social media have expressed fears of sinkholes from the underground construction. Even entrepreneur Elon Musk, who owns tunnel construction company The Boring Company, jumped into the conversation on Twitter.

So would such a tunnel system really be a logical solution for Houston’s flood woes?

Drilled 100 to 200 feet underground, the underground channels act as temporary storage for floodwater during intense rainstorms, said Larry Larson, a senior policy adviser at the Association of State Floodplain Managers. Once the rain has stopped, the stormwater can be used for a variety of purposes. It can be pumped back to the surface into a river or wetlands or even used to recharge aquifers.

If cities have a section of river that regularly overflows, a tunnel can convey extra water underground and help reduce the amount of water that flows onto land during storms, said Christof Spieler, project manager of the Greater Houston Flood Mitigation Consortium. Large-scale tunnels can also act as an additional set of waterways, taking pressure off undersized drainage networks, he said.

But Larson and Spieler said it’s hard to tell if such a system would make sense for Houston — a low-lying coastal city that’s experienced three 500-year floods in the past three years.

[…]

Flood control tunnels are nothing new to Texas — San Antonio built the San Pedro Creek Tunnel in 1991 and completed the longer San Antonio River Tunnel in 1997. Austin continues to put the finishing touches on the Waller Creek Tunnel and a tunnel in East Dallas received the long-awaited go-ahead in February.

Should the district choose to pursue the project, tunnels could cost up to $100 million per mile, Steve Costello, the city’s chief resilience officer, told the Houston Chronicle.

See here for the background. There’s a longish and very wonky conversation with Larson and Spieler about flood control, which if you read it you will know is basically an oxymoron, so do read the full article. There wasn’t any mention of other Texas flood tunnels in the earlier article, so I appreciate the Trib bringing those examples. I have a hard time imagining that this will happen here, but as noted the cost of the study is negligible, so why not at least examine the possibility? The worst that can happen is you wind up crossing it off the list.

Feds approve $5 billion in Harvey aid

Good.

Photo by Yi-Chin Lee

Almost a year after Hurricane Harvey dumped historic rains on Texas, the state will receive more than $5 billion for a range of flood control projects, repairs and studies, the Trump administration announced Thursday.

[…]

[About $1 billion] will pay for the completion of flood control projects in the Houston area that were already underway — some of them for more than two decades because of the Harris County Flood Control District’s pay-as-you-go approach — and to repair damages that those projects suffered during Harvey.

A reworked flood control project on Clear Creek in southeast Harris County, the origins of which date back to the 1980s, will receive $295.2 million. Three major bayou-widening projects will receive a combined $185 million.

The U.S. Army Corps of Engineers determined how much to allocate to each project, factoring in guidance from members of the Texas congressional delegation.

Several flood- and disaster-related studies will also be funded; The Army Corps will receive $3 million to launch an unprecedented study of the Houston region’s watersheds. Another $6 million will go toward a study that will explore how to reduce flooding in Buffalo Bayou, including when the Army Corps releases water from Addicks and Barker dams. And the Port of Houston will get $30 million to dredge the perpetually-silty Houston Ship Channel. The Army Corps also will receive nearly $1.5 million to complete a safety project to shore up Addicks and Barker dams, which have been considered at risk of failure for years.

Most of the rest will be used to build coastal levees. I’m pretty sure this is a separate pot of money than the one the city will draw from for long term housing aid. Which is fine; we can use all the resources we can get, the more the better. If you want a reminder of what the priorities should be for Harvey recovery and future flood mitigation, I refer you back to the Houston Flood Mitigation Consortium report. The Chron has more.

Greater Houston Flood Mitigation Consortium report

From the inbox:

“Strategies for Flood Mitigation in Greater Houston, Edition 1”, a report released today by the Greater Houston Flood Mitigation Consortium, calls for accelerating the paradigm shift underway in how the Houston area plans for and recovers from flooding and its consequences. While eliminating flooding in Houston is not possible, there are practical opportunities for reducing the effect flooding has on people’s lives. This initial report, which is based on current information from multiple local agencies and experts, draws a number of key conclusions on Addicks and Barker reservoirs, including the important considerations about the proposed “third reservoir,” and flood mitigation tactics such as regulations, local drainage, and buyouts.

According to Consortium Project Manager Christof Spieler, “When the consortium was formed, its philanthropic funders intended to make Houston a more resilient city and ensure that all communities benefit from flood mitigation efforts. We’ve brought together experts on flooding, the environment, and urban planning, and, together, we are presenting our conclusions thus far. We hope they are useful to decision-makers as the region figures out how to respond through funding, policies, and projects.”

The philanthropic funders include Houston EndowmentKinder Foundation, and the Cynthia & George Mitchell Foundation with additional support from the Walton Family FoundationCullen Foundation, and Harte Charitable Foundation.

 

Among the key conclusions within the report:

Flood Mitigation Infrastructure:

 

v  There is no publicly available information that clearly proves or disproves the structural integrity of Addicks and Barker reservoirs. Rather than continue to subjectively debate this topic, there is a call for a clear report on the condition of the dams, including public transparency on risks and any required structural improvements that may be needed.

v  The “third reservoir” as currently proposed is primarily intended to mitigate new development. It is not designed to reduce flooding in Buffalo Bayou nor does it solve issues with the Addicks and Barker reservoirs. The “Plan 5” reservoir defined by the Cypress Creek Overflow Study creates a scenario that allows future development of the Katy Prairie, land that currently absorbs a considerable amount of stormwater.

v  A new reservoir in northwest Harris County, specifically designed to address the Cypress Creek watershed, could significantly help mitigate repeated flooding of Cypress. A “third reservoir” in the same general area studied in the Cypress Creek Overflow Study, that targets reducing flooding in the badly damaged Cypress Creek watershed, could be very effective in addressing repeated flooding in the downstream areas of that watershed.

v  Where watersheds remain undeveloped, acquisition of land along the bayous and creeks is a cost-effective flood mitigation tool. Whether in the upper undeveloped watershed or downstream along the channel and its tributaries, undeveloped land gives the water room to spread out in a flood event, to prevent the impacts that new development on that land would have, and to preserve these green spaces for flood mitigation.

Regulations:

 

v  Under current detention regulations, new development, especially in previously undeveloped areas, still increases downstream flooding. Natural ecosystems and agricultural areas absorb some water, hold some water through ponding, and release the rest slowly. While current detention regulations limit the rate of water, the assumed conditions in these calculations overestimate pre-development runoff rate and thus underestimate the increase in runoff. The regulations also do not limit total runoff volume, which is critical in multi-day storms.

 

v  The existing regulatory system overseen by multiple jurisdictions is confusing at best and possibly counter-productive. The current patchwork approach, with platting, detention, floodplain management, infrastructure requirements, and building regulations handled by multiple entities, makes it difficult to address watersheds, and as a whole, can allow harmful projects to slip through the gaps.

Buyouts:

 

v  Buyouts studied alongside flood control infrastructure allow for determining the most effective and least expensive solutions. This proactive approach is a departure from a system that is currently reactive, only buying homes that are hopelessly deep in a floodplain.Benefits can include preventing future flood damage, providing land for better flood control infrastructure, new parks and open space, and improved housing stock.

v  Extensive buyouts without a coordinated housing plan will worsen the affordable housing shortage already confronting the region. A countywide housing plan could anticipate future housing needs, particularly after a flood event and identify locations with access to work, schools, and social services.

v  Flexible funding from non-federal sources allows more properties to be included in buyout programs and encourages property owners to participate, avoiding the “checkerboard effect.” Federal funding comes with limitations while local funding can be flexible, addressing properties within a buyout area that don’t meet federal requirements and offering compensation and relocation assistance that makes moving feasible for residents.

Public Engagement:

v  An educated public is fundamental to building and sustaining support for the long work of mitigating flood impacts. Robust engagement through the decision-making process will not only improve results but ensure equitable outcomes.

General:

 

v  The level of flood protection across watersheds is not equitable. Addicks and Barker reservoirs are already able to handle the current 1 percent design storm. Even with the federal projects, Brays Bayou, Clear Creek, Hunting Bayou, White Oak Bayou and Greens Bayou will not be able to handle the 1 percent storm, and tributaries of those bayous, and well as several other major bayous like Cypress Creek and Vince Bayou have not been studied in detail or had projects identified.

v  Most flood control assessments, including the federal government’s cost-benefit ratio, calculate benefits through economic value, not impact on human lives. We can measure projects by the number of people who benefit or use more sophisticated tools like Social Impact Assessment.

A link to the full report can be found houstonconsortium.org.

In the coming months, watershed analyses will be completed, which will allow for more detailed conclusions and Edition II will include these findings.

See here for a bit of background, and here to find the report. It’s one thing to come up with good and constructive ideas, it’s another to get them implemented. You can start out with the support of political leaders, you can persuade them to adopt your ideas, and you can elect people who campaign on the promise of pursuing those ideas. I look forward to the next step in this process, because we’re going to need one. The Trib has more.

Thinking big about fighting flooding

Christof Spieler, on behalf of the Greater Houston Flood Mitigation Consortium, comments on a proposal to move forward post-Harvey.

On Oct. 25, Harris County Judge Ed Emmett released 15 recommendations for mitigating damages from future flood events. The researchers collaborating through the Greater Houston Flood Mitigation Consortium appreciate his willingness to release his priorities for public review and discussion.

The consortium was established by the Houston Endowment, Kinder Foundation and Cynthia and George Mitchell Foundation to provide the public and decision-makers with important information so that Harris County and related watersheds can be rebuilt as a stronger, more resilient, more equitable and more livable region.

We found Judge Emmett’s list to have many merits. The consortium is thoroughly assessing the implications of the 15 recommendations and plans to share our conclusions soon. In advance of detailed conclusions, we have organized the issues into six broad themes.

See here for the background. You should read the whole thing, but I’ll give you those six broad themes: Structural projects, green infrastructure, risk education, development and buildings, planning, and governance. There’s a lot to do, but there’s a lot to talk about first, and the conversation is just beginning. Read and see what you think.