HCFCD and partner spending by watershed since 2000.

For Better Flood Mitigation, Let’s Dig a Little Deeper

When I say “dig a little deeper” to improve flood mitigation, I’m speaking metaphorically, of course.

On September 17, 2023, Jim Blackburn, a lawyer and professor of environmental law in the Rice University engineering department, published an article in the Houston Chronicle. He titled it, “What Houston’s next mayor needs to do about flooding.”

Both Prof. Blackburn and the Chronicle labeled the article “opinion.” That’s fortunate because in some areas, Blackburn made assertions contradicted by facts. In most other areas, he made high-level recommendations without any specifics.

For example, among other things, Prof. Blackburn argues that Houston’s next mayor should:

  1. Build more mitigation projects for Halls and Greens Bayou Watersheds, which he says haven’t received their fair share.
  2. Address climate change with better planning and engineering tools.
  3. Speed up buyouts.

Let’s examine each and why we all need to dig a little deeper if we want to improve flood mitigation.

Halls and Greens Bayou Watersheds

Both Halls and Greens watersheds HAVE received mitigation projects. Many. And more than their fair share. You can see it in spending data and on the ground. However, Harris County Flood Control District has delivered the projects, not the City of Houston. 

HCFCD and its partners have spent more than $390 million on Greens and Halls mitigation improvements since 2000. Greens has received more dollars than any other watershed except Brays (where Rice is). And tiny Halls ranks third in dollars per capita among all watersheds.

Professor Blackburn and his graduate students need to dig a little deeper. They should get out more and smell the construction dust. For example, here is a new Halls Bayou detention basin, one of many built in the watershed during the last 10 years

New Halls bayou detention pond
New Halls Bayou Detention Basin west of Keith Weiss Park, photographed in March 2022.

Then, there’s this new detention basin along Greens Bayou at Cutten Road under construction in 2021. Again, it’s one of at least a half dozen built in the last ten years along Greens.

Cutten basin
One portion of the massive Cutten Road stormwater detention basin on Greens Bayou

I compile flood-mitigation funding by watershed through quarterly FOIA requests. I also cross-check the data by photographing construction from the air.

Photos such as those above support the spending reported below. However, neither the photos nor the spending data fit the current, popular political narrative about “historical disinvestment” in low-income minority neighborhoods.

Includes both Harris County and partner dollars

Of the top five watersheds above, four have a majority of low-to-moderate income residents; only Cypress Creek does not. Those five watersheds have received 60% of all funding going back to 2000, compared to 40% for the other 18 watersheds put together.

From high to low in the graph above, spending varies by 130X. Such data shows that many watersheds have been historically deprived – in the name of “equity.” But those deprived tend to be on the more affluent end of the spectrum.

Address Climate Change with Better Planning and Engineering Tools

Next, Professor Blackburn wants to address climate change with better planning and engineering tools. It’s hard to see what more the next Mayor of Houston could do in this regard. 

Professor Blackburn asserts that we need to “understand our changed rainfall patterns and integrate that knowledge into every aspect of the City’s thinking.” 

Since Harvey, the City has already adopted NOAA’s new Atlas-14 rainfall-probability statistics and incorporated them into its regulations. So, design professionals are already working on new, updated assumptions.

Plus, NOAA is currently working on Atlas 15 which predicts future impacts of climate change. But NOAA won’t release those stats until 2027 at the earliest – after the next mayoral election.

Professor Blackburn, a reputed expert, doesn’t define how climate is changing, but asserts that professionals should consider the changing patterns. He believes they should engineer “streets, sewage treatment plants, underground and above-ground stormwater systems, floodplains and general drainage flow patterns” with the unspecified climate patterns in mind.

It’s hard to argue against progress. But the real issue, in my opinion, is that leaders in many surrounding cities and counties have not yet uniformly adopted NOAA’s Atlas 14 standards. Perhaps the next Mayor could jawbone them into sending less water downstream

The Mayor could also discourage large increases in impervious cover under proposed programs such as the Houston Planning Commission’s so-called Livable Places. Livable Places would disproportionately increase flood risk for low-income and minority neighborhoods because of the program’s linkage to mass transit.

Speed Up Buyouts

Blackburn believes that buyouts should happen faster after a flood – before people rebuild. Most people agree that the process needs streamlining. But how?  

Experts have proposed multiple improvements. However, none has gained traction across the board with local, State, and Federal lawmakers. 

For instance, after Harvey, Harris County Flood Control executives pitched plans in Austin for a QBF (Quick Buyout Force). Instead of waiting for:

  • The President to declare a disaster
  • Congress to vote funds
  • FEMA to design rules for disaster relief
  • The State to adopt them
  • Local agencies to identify eligible recipients and solicit applications
  • Local, State and Federal authorities to review and approve the applications, and 
  • Money to flow through the pipeline…

…HCFCD argued for pre-approval of guidelines and to have a pot of funds available before disaster strikes, kind of like a savings account for a rainy day. Money could then be used immediately. Local agencies would later reimburse the Federal government for money they didn’t use.

Houston’s next Mayor could throw his/her influence behind such a plan or a suitable alternative.

Unfortunately, Prof. Blackburn doesn’t recommend a plan. Nor does he dissect each issue and give us the benefit of his wisdom. With all the brainpower and resources at his disposal, he could make a genuine contribution to the community. Perhaps his future opinion pieces will elucidate how we should improve beyond simply preparing for the future. 

Collectively, we all need to dig a little deeper to improve flood mitigation. We need to start with facts and get down to specifics.

Posted by Bob Rehak on 9/27/2023

2220 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Major funding announced for Cypress Creek Detention Project by Crenshaw, Harless, Ramsey and Petersen

Funding Announced for Massive Detention-Basin Complex on Cypress Creek

9/25/23 – Approximately 425,000 people live in the 204 square mile Cypress Creek watershed which has severe repetitive flooding. At a press conference this morning, County, State and Federal officials announced $50 million in funding for a massive complex of stormwater detention basins on Cypress Creek at T.C. Jester Blvd. to help protect those people.

The basins will span approximately 150 acres on both sides of T.C. Jester and include 1200-acre feet of planned stormwater detention capacity, wet bottoms, and recreational trails.

Approximate boundaries of three detention basins – one will go west of TC Jester and two more east. White area is existing basin.

Altogether, the stormwater detention capacity in this area will increase approximately 75X.

Google Earth calculation of existing and planned ponds

The existing pond covers approximately 2 acres and the new areas will cover more than 150.

Looking E over T.C. Jester. Existing 2-acre basin in foreground was site of press conference. Wooded area beyond will become two new detention basins.

Thanks to County, State and Federal Governments

The $50 million will come from three primary sources:

Harris County Flood Control District Executive Director Tina Petersen also reminded everyone of the money designated for Cypress Creek in the Flood Bond, which was considerable.

The GLO/HUD money has been requested but not yet confirmed although all indications are positive at this time. GLO Commissioner Dawn Buckingham has committed to making sure that people in all parts of Harris County benefit from the $750 million.

Timetable and Project Scope

HCFCD Director Dr. Petersen addressed the next steps in the projects. “A portion of the projects on the east side of T.C. Jester will start construction in the next 6 to 9 months. The remainder should go into construction no later than the end of 2024. So we’re going to see these projects move quickly. This type of progress would not have been possible without the critical funding that our Congressman and Representative secured “

The overall project includes three stormwater detention basins within a broader footprint. Two basin compartments are on the east side of T.C. Jester Boulevard and another is on the west side.

Excavation of the west side basin (see below) has already begun under an E&R (Excavation and Removal) Contract. A private contractor is removing the dirt, almost free of charge, then selling it at market rates to recoup costs and make a profit. An estimated 120,000 cubic yards of material has already been excavated to date.

Work to date on basin west of T.C. Jester. Looking N toward Cypresswood Drive.

The contractor began removing dirt in the general area to get a head start on construction, even before final design of the basin. The final design will begin soon.

Each basin will have a wet-bottom with maintenance berms, side slopes and high banks along the outside.

Construction for all basins should begin no later than Q4 2024. They have estimated 8-month construction timelines.

Extent of Benefits

The three stormwater detention basins will work together – taking stormwater from the main stem of Cypress Creek and holding it until water levels recede on the main stem.

The projects will also have recreational benefits such as hike and bike trails.

Director Petersen stated that the projects will primarily benefit the local area, i.e., benefits will not extend very far downstream. The 1200 acre feet will likely take several thousand homes out of the floodplain.

Even though those homes will be in the Cypress Creek area, 1200 acre feet being held back upstream is 1200 acre feet that won’t be in the living rooms of Lake Houston Area residents during the next big flood.

More to Come

Ramsey also pointed to more projects to come, though he didn’t elaborate. He said, “This is $50 million of the $100 million that will be spent over the coming months in the Cypress watershed. So hold on. We’re getting started. This isn’t the end. This is the beginning.”

Speakers at T.C. Jester Detention Basin Press Conference included U.S. Representative Dan Crenshaw, State Representative Sam Harless, Harris County Precinct 3 Commissioner Tom Ramsey P.E., and HCFCD Executive Director Dr. Tina Petersen.

Posted by Bob Rehak on 9/25/2023

2218 Days since Hurricane Harvey

Urban Flood Risk Handbook by World Bank

Review: Urban Flood Risk Handbook

The World Bank recently published the 177-page Urban Flood Risk Handbook: Assessing and Identifying Interventions by Scott Ferguson, Mathijs van Ledden, Steven Rubinyi, Ana Campos, and Tess Doeffinger.

The book is primarily targeted to flood-project managers and city officials. However, the informative illustrations and easy-to-understand writing make it a useful primer for anyone who wants to become more knowledgeable about flooding.

The World Bank bills the handbook as a “roadmap for conducting an urban flood risk assessment in any city in the world.”

What will the average person get from it? The ability to understand flood professionals, the issues they face, and how they evaluate problems/solutions.

It also made me realize that Harris County’s equity framework, which the county uses to allocate flood-mitigation funds, fails to incorporate many factors recommended by the Department of Homeland Security and others.

Outline of Handbook

The book contains five chapters.

Chapters cover the following sub-topics.

Intro and Chapter 1: Defining Risk

Much of the book has a checklist quality to it. For instance, what should professionals quantify when defining flood risk?

  • Hazards and their probabilities
  • Exposure – an inventory of elements and activities affected by hazards, for instance:
    • The population and its assets such as homes and belongings, private businesses, and industrial assets
    • Infrastructure such as roads, drinking water, sanitation, drainage, and flood protection infrastructure
    • Public infrastructure like health care and school facilities
    • Environmental and cultural assets
    • Economic activities.
  • Vulnerability – the degree to which people, property and infrastructure can be adversely affected

Here, for instance, I was surprised to learn that Harris County’s equity framework considered some, but not all of the factors that make areas vulnerable. For instance, it doesn’t really incorporate infrastructure!

Chapter Two: Hazard Assessment

The chapter on Hazard Assessment begins with a list of “boundary conditions” typically used within a flood model.

Five conditions typically include: (1) rainfall, (2) infiltration, (3) flow, (4) water levels and waves, and (5) pumps and flow control structures.

But just measuring rainfall can be difficult depending on the number and types of gages in use. “Most meteorological services only provide daily values (mostly from manual gauges), which provide part of the overall rainfall characteristics. However, the distribution and intensity within a single day are essential,” say the authors.

Automated gages that can measure short (sub-daily) periods are critical in informing regulations that affect the design of infrastructure. Short, high-intensity bursts are a significant factor in urban flooding. However, many areas have gages measured manually once per day. (The Flood Control District’s are all automated.)

As I scanned the text of this chapter, flashbacks from Harvey kept recurring. When I read this sentence, I thought of the Lake Conroe discharge designed to prevent the flooding of Lake Conroe homes. “Discharge rates from control gates normally relate to both upstream and downstream water levels…” [Emphasis added.] Did the dam operators consider downstream water levels at the time? The case is still pending in the courts.

In chapter 2, I also found the most illuminating discussion of differences between 1D, 2D and 3D modeling that I have ever read.

Ditto for a description of Manning’s Coefficient, which is used to estimate the impact of friction on the speed of water, which in turn affects the rate of accumulation and flood height.

Illustration of Mannings Roughness Coefficient and friction’s impact on speed of floodwater.

Trees and buildings create friction for floodwater that slows it down. But concrete and clear-cutting speed it up.

Such information is used to quantify the potential consequences of flooding to homes, businesses, and people across an area.

Chapter 3: Risk Assessment

Chapter 3 focuses on Risk Assessment and lists types of infrastructure that the Department of Homeland Security defines as “critical sectors.”

Again, Harris County’s Equity Framework (used to distribute flood-mitigation funds) considers none of these.

Chapter 4: Interventions

Chapter 4 discusses types of interventions (solutions to flooding). They fall into three main categories.

The chapter then addresses the limitations, applicability, costs, benefits, and environmental/social impacts of each.

It’s too complicated to summarize here. But it’s fascinating to see how flood professionals evaluate the range of options.


The last chapter addresses the business side of flood mitigation, i.e., bidding jobs. I’ll skip that here and close by saying this. Even after studying flooding for six years, I felt lights turning on almost every time I turned a page in this book.

I had a high level understanding of most of the concepts. But this gave me a much fuller understanding. I found myself constantly thinking, “Aha, so that’s how that fits in.”

And it’s a free download!

Kudos to the World Bank and the authors. They have provided a valuable addition to the literature.

Posted by Bob Rehak on 9/24/23

2217 Days since Hurricane Harvey

Used with permission of World Bank