On April 5, 2018, the Greater Houston Flood Mitigation Consortium released Edition 1 of their Executive Summary report.  The report provides “information relevant to the local, state and federal investments being discussed for flood mitigation in Harris County.” The report also “summarizes the strategies that are in the Houston area’s toolbox and focuses on specific challenges and a variety of conclusions about how best to address both strategies and tactics.”

The report is 64 pages long, with a light gray font that is eye-strainingly small if printed out in hard copy format.  I’d suggest reviewing the report for more details, but don’t print it out. You should review the PDF report in digital format with a 150% zoom enabled.

This post will provide a few of my thoughts and reactions to the material in the report.  This should not be considered a summary of the report. For that, I’d suggest reading the report’s Section 6.0 – Conclusions.

Storm Surge: It was noteworthy that consideration of storm surge was excluded from the consortium’s work effort and the report. While the risk of storm surge is certainly much less than 1% per year, the negative consequences of a worst-case surge are very large.

Political Will: The report mentions the role of “political will” in planning and responding to flood risks. Someone involved in regional water planning once called me on my use of that phrase and since then I’ve tried to avoid using the term.  With a bit of online research, one can see that there is not a good definition of what it is. One good one I found suggests that it consists of three elements: (1) Opinion, informed by both knowledge of the issue and how the issue is framed; (2) Intensity, the depth and strength of the viewpoints held; and (3) Salience, the degree of importance of the issue and how passionate stakeholders might be about it.  .

Pot Shots at Developers: The report takes a few (perhaps) unwarranted shots at developers.  For example: “… there are instances when developers have found ways to work around the [regulatory] system.” (p. 2)  To support this statement I’d like to see a more detailed description of what situation was actually observed and how the circumstances were handled. At this point I pretty much expect mainstream media to rehash the narrative that development is to blame for all flooding and that new development doesn’t include mitigation, but I would have expected the Consortium report to avoid restating any portion of that narrative.

Principles: I support pretty much all of the principals presented in the report. A focus on human impacts over property impacts makes sense. Collaboratively and inclusively determining what level of risk we are willing to accept is key (because it’s not physically possible to achieve a zero risk level and we can’t afford to achieve an extremely low risk level). Collaboration and coordination across watersheds should be undertaken.  Risk communication is very important.  Using both structural and non-structural strategies should be used. We should implement solutions at different scales. Preserving and restoring ecosystems will be helpful. Science-based decision-making is preferable.  Learn from other regions and nations. Understand the network relationships and that flooding is connected to other concerns. The only principle that gives me pause is the call for limiting new development “where necessary to mitigate downstream flooding and keep people and property out of harm’s way.”  My main concern about this relates to private property rights and our collective ability to pay current landowners for the use of their property (to avoid a constitutional takings claim).

Offsite Flows: The report incorrectly states that land development engineers “typically focus on mitigating the runoff generated by their development project, and as such, flows entering onto their site from other sources may not be considered in their design analysis.”  This is just not true.  Offsite flows are always considered and engineers cannot obtain a development permit without addressing offsite flows. Ok, maybe, if the development site is surrounded by existing development that conveys water away from the subject site, we might not consider offsite flows; but in that case, why would we?

Flood Warning Systems: I strongly agree and support this idea. The report provides a good overview of the issues and the emerging capabilities.

Green Infrastructure: The report provides a good overview of these ideas along with rational and appropriate caveats about our topography and soils so that the reader might understand that green infrastructure approaches are not a silver bullet.  As I’ve written previously, we need to do more field infiltration testing to learn more about what is possible with soil amendments, deep root vegetation, and actual field conditions.

Sea Level Rise and Climate Change: Both are mentioned, contrary to some accounts of this report that suggested the report is silent on these topics.

Clarity About a Third Reservoir: The report does a good job of outlining the potential benefits and costs of any potential third reservoir (depending upon its design intent).  Many have called for its construction without being detailed about its purpose. Is it to mitigate new development flows? Is it to reduce the probability and frequency of Addicks and Barker overflows?  Is it to reduce the frequency of Cypress Creek overflows?  Is it to preserve the Katy Prairie?

Watershed Discussions: The report includes some great, factual, and thoughtful discussion about all of the major watersheds in the Harris County region. You should definitely read about the watershed in which you reside. There are also some great details about our level of investment, population stats, and the level of risk exposure in each watershed that should be more widely known.

Probabilistic Flood Analysis: I like the idea of using a Monte-Carlo or statistical method of estimating flood risk.  This would be in place of deterministically modeling each storm sewer, swale, channel, or bayou.  I wonder, however, if the various federal and state governing organizations (think: Federal Emergency Management Agency and National Flood Insurance Program), as well as lenders and reinsurance companies, would accept that type of risk mapping product?

Conclusions: Section 6 of the report is only five pages long. If you don’t have time to read through the entire document I would encourage you to read the conclusions.  Some very good thoughts and ideas for all Houston-area stakeholders to consider.