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Greater Houston Flood Mitigation Consortium

We’re still figuring out how to do development in a floodplain

From the inbox:

The Greater Houston Flood Mitigation Consortium has released dual research reports that examine current standards in the area’s drainage, detention, and development regulations. The reports also include findings that encourage implementation of new and updated flood management infrastructure approaches and regulations to mitigate the risk of future flooding.

According to Consortium Project Manager Christof Spieler, “This research is intended to inform and unite our city and county leadership, development community and residents in planning for our region’s future. Some of the current regulations are not sufficient to address current flood risk and are further compounded by our region’s growth. Taking time to consider how we could benefit from updated regulations isn’t trying to limit that growth, but would set into motion the research and creative solutions required for growing in more resilient ways.”

Research Paper 1: Detention & Drainage Regulations:

According to researchers from Rice University’s SSPEED Center and report contributors Houston Advanced Research Center, as more and more land in and around Houston is developed, runoff and an inability for the land to absorb water from heavy rain events become contributing factors to flooding. The report goes on to identify areas where current detention regulations, which are in place to prevent those negative impacts, may in some situations be allowing new development to increase downstream flooding.

Specifically, the report findings state current regulations, with the biggest impact being from projects of 50 acres or less on greenfield sites:

  • Overestimate the runoff from some undeveloped sites and, as a result, underestimate detention required to maintain current conditions;
  • Use one-size-fits-all drainage formulas that do not reflect the variation in soils, vegetation and topography across the county; and
  • Only address maximum flow rate, not total runoff volume, meaning the cumulative effect of multiple developments can still increase flood levels. Further, downstream flooding can last longer while multi-day events can have a greater impact even if current requirements are met.

Suggestions to improve current regulations:

  • Increase the default minimum detention requirements set by the City of Houston and Harris County Flood Control District for development sites of all sizes to be a more conservative figure.
  • Allow developers / property owners with sites of any size to provide less than the default minimum detention requirements, provided there is an engineering study, based on field operations, that quantifies pre-development runoff.
  • Install gauges to collect measurable data on runoff in a variety of undeveloped watersheds.
  • Commission engineering studies for the undeveloped portions of Harris County’s major watersheds to understand cumulative effects and determine appropriate parameters.
  • Based on the studies, set specific criteria for the watershed, which could be coordinated across multiple jurisdictions in the watershed.
  • Require evaluation of cumulative effects across entire watersheds.
  • Require evaluation of multi-day events (three, five or seven days) as well as storms lasting a day or less.

Research Paper 2: Development Regulations:

According to the researchers from Kinder Institute for Urban Research Rice UniversityTexas Southern University, and Houston Advanced Research Center, the region can embrace a form of growth and innovation that sees opportunities in rules and systems that encourage resilient growth to avoid placing people and property in harm’s way.

Suggested approach for considering new regulations and policies:

  • Create regulations and policies to ensure both residents and officials understand that there is a range of flood risks both in and outside of current mapped floodplains.
  • Create systems that utilize both green and gray infrastructure elements for public and private infrastructure to maximize our ability to mitigate flooding.
  • Create land use and development policies that minimize future risk and address existing issues rather than relying too much on expensive infrastructure projects.

The report points out that these regulations are instituted and enforced by a variety of jurisdictions and operate within a legal framework set by the Texas Legislature. Changing the framework can require actions at many levels, and no one entity is solely responsible. Keeping the above points in mind and considering best practice research, key report takeaways include:

  • Tailor new developments to avoid at-risk areas in such a way as to keep people and structures from harm’s way and to reduce the number of existing vulnerable residents and structures.
  • Adopt regulations that inform residents about their flood risks and their options to mitigate those risks. This information should be proactively accessible to homeowners and renters both in and out of the mapped floodplains.
  • Provide public funding and programming to assist low-income residents in bringing their older, flood-prone homes up to new standards.
  • Require design standards and development permitting to incorporate broader resilience goals to help facilitate a more resilient region.
  • Implement regulations and design standards to encourage both green and gray infrastructure solutions to maximize our ability to reduce flooding. In order to see their use increased, green infrastructure efforts should be incentivized or even required, as the City of Houston is now studying.
  • Successful stormwater and floodplain management needs to be implemented at the regional level with the cooperation of city, county and regional institutions. Stormwater and floodplain management professionals within these institutions are best suited to put into place new and emerging best practices.
  • Balancing economic goals with regulatory reform can be a struggle. As new data and technology reveal a new picture of flood risks for the Houston region, this balance will likely shift, resulting in the need for a new set of regulatory practices. This report summarizes best practices that are potentially relevant for the Houston region.

A link to both reports can be found at  houstonconsortium.org.

flooding, harvey
See here and here for previous research, and here for the Chron story. I don’t have anything to add, I just hope Commissioners Court and the Lege are paying attention.

Still lots of houses at risk of flooding

This is going to take a long time to really mitigate.

A new study is raising concerns that restrictions on new construction put in place after Hurricane Harvey could leave low-income residents with fewer choices for affordable housing.

More than 475,000 people in Harris County live in multifamily units at risk of flooding, according to the study released Thursday by the Greater Houston Flood Mitigation Consortium. The group includes the University of Houston, the Kinder Institute and the Local Initiatives Support Corporation, among others. Even without the flooding risk, units are becoming less and less affordable.

“The issue of flooding and the issue of affordable housing are very connected,” said Christof Spieler, the consortium’s project manager. “We have a lot of Houstonians who are in the difficult position where the housing they can afford is the housing that puts them at risk of flooding.”

In Harris County, 26 percent of all multifamily units — buildings with two or more units — are currently located within a flood-risk area. After Harvey, Houston leaders passed an ordinance known as Chapter 19 that requires elevation for rebuilding in the flood plain. The down side, according to the consortium, is that this requirement may lead to the loss of affordable multifamily units in the floodplain.

“Chapter 19 has the best interests of people in mind, but I just don’t think that we really thought through the potential impact on multifamily units,” said study co-author Susan Rogers, the director of the University of Houston’s Community Design Resource Center. “I don’t think any of us want to encourage apartment owners to continue to renovate and put people in (apartments) clueless of what could happen to them.”

While most of the multifamily units in Houston that are being rebuilt were permitted before the ordinance took effect, researchers heard through focus groups that property owners are worried about what will happen after the next storm.

“If you’re trying to keep affordable units, but safe and not-falling-apart units, you don’t want reputable property owners to either go bankrupt and abandon their properties to the kind of ‘owner of last resort’ who will potentially not bring things back up to where they should be,” said Kyle Shelton, director of strategic partnerships at Rice University’s Kinder Institute and another of the study’s lead authors.

The press release is here, the full report is here, and Mayor Turner’s response to this report is here. All of the Consortium’s research is here if you need to read more. I don’t have much to add to this, just that if we want to make good policy decisions to fix the mistakes of the past and prevent making more of them in the future, we really need to understand the full scope of the issues. I’m glad we have this group doing that work for it.

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.