Forest Cove Townhomes: One Down, Two to Go

On 7/5/2022, demolition began on the first of three townhome complexes remaining on Marina Drive in Forest Cove. The complexes had been damaged beyond repair when 240,000 cubic feet per second of stormwater roared through them during Hurricane Harvey.

Since then, the abandoned properties had become magnets for drug dealing, arsonists, and illegal dumping. But the buyout process stalled when owners of some of the units could not be found. The county had to exercise its powers of eminent domain on those by declaring the purchase of several units a “public necessity.”

Now, with legalities out of the way, demolition began at 4:45 Tuesday afternoon. You could almost hear a collective sigh of relief from Forest Cove residents. Removal of the eyesores will restore the community’s image while eliminating a public safety hazard.

Photos of Demolition

Here are some pictures taken between 7/5 and 7/9/22. All that’s left of the first complex is a shrinking pile of rubble, some twisted girders, and some driveway.

Forest Cove Townhome Demolition
Beginning of Forest Cove Townhome Demolition on 7/5/22
By end of second day, 7/6/2022, half of first complex was down, but most of rubble remained.
By end of third day, 7/7/2022, entire first complex was down. Contractors compacted rubble to make it easier to haul it away.
They also separated girders from the rubble. This EPA article describes recycling opportunities for demolition waste.
End of fourth day, 7/9/22. Most of waste was hauled away. Practically nothing remains of first building. Second complex in background will come down next week.
Pile of twisted girders. Remnants of a once proud townhome complex and a laid-back river lifestyle. Next up for demo: the building in background.

Next Steps

The next steps:

  • Demolish building in photo above 7/14/22.
  • Schedule demo of third building as soon as last buyout is completed.

Kudos to Harris County Flood Control and its contractors. This is not easy work when the temperature soars into triple digits. Their efforts will make a huge difference to the community.

Posted by Bob Rehak on 7/10/2022

1776 Days since Hurricane Harvey

Response to Concerns About Flood Mitigation Benefits Index (Part II)

The letter below expresses disagreement with two recent ReduceFlooding.com posts about a proposed Flood Mitigation Benefits Index. It is from Michael Bloom, P.E. While I disagree with almost all of his claims, I am reprinting his letter verbatim because I encourage healthy debate. Compare the posts and draw your own conclusions. – Bob Rehak, Host, ReduceFlooding.com.

This is Part II of my two-part article providing responses to concerns raised by my colleague on the Community Flood Resilience Task Force (CFRTF), Mr. Bob Rehak about the FMBI. If you missed Part I, you can read it here.

Why are we Using the Index When it Produces Inconsistent Results that are Not Intuitive? Mr. Rehak provides an example that holds the current population and current risk the same, but changes the total prior investment amounts, as illustrated in the table below:

Prior
Investment
($)		Current
Population
(Number)		Current
Risk
(% Annual Chance)		FMBI
Area A100,0005,000102
Area B1,000,0005,0001020

Mr. Rehak looks at these results and writes: “So, spending more money to get the same results increases benefits? Shouldn’t it be the opposite? That’s both depressing and confusing. You spend 10X the money; flood risk remains the same; and the “benefit” increases!!!??? You would think spending less money to achieve identical results would be more beneficial. It certainly is for taxpayers.”

Everyone should be depressed and confused by this result if the FMBI was illustrating the results for the same location. Mr. Rehak appears to make that inference when he writes: “spending more money to get the same results increases benefits.”

But Area A and Area B are two different locations. The FMBI is just telling us what the current conditions are at two different locations in the county. One location had 10 times the prior investment than the other – but both locations still have the same current risk.

Worse, in this case, BOTH locations have risks that are ten times the current standard of care for new developments – which require structures to have less than a 1% annual chance of inundation. Clearly, both locations need more flood risk investment. The FMBIs of 2 and 20 both are extremely low, meaning they need help, regardless of the prior investments. A high FMBI indicates that no additional help is needed in that location. A low FMBI indicates that additional help is needed in that location.

The table included in the middle of my February 17, 2022, post entitled “How Should We Decide Where to Invest in Flood Risk Reduction?” presents additional examples showing how the FMBI changes from location to location with only one changed variable. It also provides narrative explanations of each sequence. Notice how the index values are greater than 3,000 (sometimes greater than 20,000 or 100,000) in locations where the current annual chance of inundation is less than 1%? Again, a high FMBI means we don’t need to make more investments in that location. A low FMBI means that location needs more help.

Isn’t the FMBI Trying to Prove Inequitable Investments in Flood Risk Reduction? To some extent, partially, yes, it is. This was always an important aspect of the FMBI, when it was originally proposed as the “Flood Benefits Index (FBI)” by Dr. Erthea Nance and Iris Gonzalez in May 2021. I have continued to advocate for its use as one of four input variables we should use to create our county-wide “heat map.” This is explained in more detail in my other article. Mr. Rehak is concerned about the taxpayer. I am also. I don’t think the taxpayers of Harris County should pay for flood risk reduction projects in areas that already have a high FMBI. Said another way, it is a waste of taxpayer money to invest in additional flood risk reduction projects in areas currently with less than a 1% annual chance of inundation.

Isn’t the FMBI Measuring per capita Investment Associated with a Certain Level of Flood Risk and Mistakenly Calling that a “Benefit?” Mr. Rehak writes: “The more people you help with any given sum, the more the benefit goes down. Voila! That makes it look as though the highly populated watersheds (that have received the overwhelming majority of prior investments) have received little benefit. And that may be the point of this formula. It will send even more money to those same areas.”

This interpretation again seems to stem, I think, from Mr. Rehak’s belief that the index will be used to compare the same location at different times – before and after various investments. This is not the proposed use of the index. The proposal is to use the index to describe the current conditions at all locations in the county at the same time.

I’m not sure I understand Mr. Rehak’s concern about the index being a per capita value. The more people in an area who benefit from prior investments the better. Wouldn’t we want to invest in areas that help the most people?

The blue-shaded area of the table in my earlier post illustrates how population differences between locations will change the index value among those locations. For convenience I’ve repeated the table below:

Hypothetical examples.

Mr. Rehak accurately notes that the index goes up in locations with fewer people and down in locations with more people; this will incentivize planners to direct future investments in those higher population areas. He writes: “The more people you help with any given sum, the more the benefit goes down.” This is true, but Mr. Rehak’s statement doesn’t connect it to the past and it omits how the index will be normalized by area size. Index values will be calculated for similarly sized areas. This will allow an apples-to-apples comparison of per capita investments. The index is intended to incentivize future investments in areas with more people in cases where risk and prior investments are equal because we want to help as many people as possible.

By Michael Bloom, P.E.

Posted by Bob Rehak on 7/10/2022

1776 Days since Hurricane Harvey

If you have views on this subject, please share them through the contact form on this website.

Response to Concerns About Flood Mitigation Benefits Index (Part I)

The letter below expresses disagreement with two recent ReduceFlooding.com posts about a proposed Flood Mitigation Benefits Index. It is from Michael Bloom, P.E. While I don’t agree with all of his claims, I am reprinting his letter verbatim because I encourage healthy debate. Compare the posts and draw your own conclusions. – Bob Rehak, Host, ReduceFlooding.com.

One of my colleagues on the Harris County Community Flood Resilience Task Force (CFRTF) – Mr. Bob Rehak, as well as Commissioner Tom Ramsey, P.E., and others have asked me about the proposed Flood Mitigation Benefits Index (FMBI). After hearing some of the questions, and reading two recent blog posts by Mr. Rehak at Reduce Flooding, one on July 2, 2022 – Questionable Validity of Flood-Mitigation Equity Formula and on July 6, 2022 – Formula for Allocating Future Flood-Mitigation Funding Deceives, I figured I should provide a more detailed explanation of the index and directly address some of Mr. Rehak’s concerns.

In addition to getting to know Mr. Rehak while attending CFRTF meetings, Mr. Rehak and I have sat down, in person, a few times since both being appointed to the Task Force in order to discuss difficult issues, in particular the FMBI. I appreciate his candor and our ability to respectfully debate things – one might say – politely argue. This post (and Part II) are extensions of those discussions so others can benefit from the exchange.

I first described the FMBI in an article I published on February 17, 2022, entitled “How Should We Decide Where to Invest in Flood Risk Reduction?” The FMBI is explained about halfway down the post. To recap, the index is equal to:

Variation on formula presented to Commissioners Court on 6/28/22. It omits the word “Density” after population. See discussion below.

The index is intended to be calculated for all locations in the county at one particular time to help define the baseline conditions. The index will be used to help plan where additional flood risk reduction investments should be made. An area with a high FMBI has already received higher per capita investments, has a low risk, and therefore doesn’t need additional help. An area with a low FMBI has received little per capita prior investments, has a high risk, and therefore does need additional help.

Responses to Specific Concerns

Which Type of Project Costs Are Included? Does including construction costs, but excluding design, right-of-way acquisition, and operational costs skew the data? Since this is an index that will be calculated for all areas of our county, costs included or excluded will not adversely impact the results.  Using the index to compare conditions in various areas within our 1,700 square mile county will still be valid if the index is calculated in all areas of the county the same way. This is an example of “normalizing” the data. It allows for an apples-to-apples comparison among and between locations. It will help us pick where to invest in the future. Since land acquisition, design, and other non-construction costs are often a similar percentage of the construction costs, their exclusion from all index calculations will keep things consistent and unskewed.

Which Agency Investments are Included? Will excluding investments from Harris County Commissioner Precincts, cities, municipal utility districts, and other entities skew the data. I actually agree with this, the investment dollars will be slightly low, but only by a little bit. I anticipate that the total amount of flood risk reduction investment dollars made by these entities will be very, very, very small compared to those made by the Harris County Flood Control District (HCFCD) and the Civil Works program of the U.S. Army Corps of Engineers (USACE). Because of this difference in the size of these investments, I anticipate that the impact on the index calculation will be negligible. HCFCD has agreed to provide their investments from 2000 to 2020. Dr. Denae King and I have submitted a Freedom of Information Act (FOIA) request to the U.S. Army Corps of Engineers, the Federal Emergency Management Agency (FEMA), and the Natural Resource Conservation Service (NRCS) to identify all flood risk reduction investments going back to 1937 – the year the HCFCD was created to serve as the “local partner” to help secure federal investments through the USACE. These requests exclude repair and recovery dollars since those expenditures don’t permanently reduce flood risks.

What Risk is Included in the Index? Does the risk used in the calculation reflect the risk before or after mitigation efforts? The risk value used is the current risk. It is the risk remaining after accounting for all risk reduction investments “counted” in the numerator. The index reflects one point in time and should be recalculated every five years or ten years, much like the Social Vulnerability Index published by the Centers for Disease Control. The population and risk values will be based on the same snapshot in time. The investment value will be based on the sum of all investments made prior to that moment in time (adjusted for inflation).

Why Include Investments Back to 1937? Why consider investments made in areas of the county that were undeveloped back then? Won’t this radically skew the comparisons? Including all investments back to 1937 is vitally important because the vast majority of the flood risk reduction investments made in the county were made by the federal government through the Civil Works program of the USACE. HCFCD was CREATED in 1937 to be the local sponsor for USACE projects. Addicks, Barker, Buffalo Bayou, Brays, White Oak, Sims, Clear Creek, and many other projects, many of them initiated prior to 2000, all significantly reduced flood risks for structures that exist today. Even if the project was initially constructed in an undeveloped area, it still benefits structures that were built later and that exist today. That’s why the investment amount is a cumulative value (inflation-adjusted) and the risk value is today’s value. This approach won’t radically skew comparisons because all three of the values will be determined for all parts of the county in the same way.

Why only Consider Mitigation Investments? Doesn’t flood risk depend on many factors – not just mitigation investments? Yes, current flood risk depends on many factors, including development rules, building codes, finished floor elevations, development locations, and improvements to our understanding of rainfall statistics. The risk value in the index is not intended to measure the risk reduction obtained from prior investments. The risk value in the index is intended to present the current risk. The current risk reflects all factors, including prior mitigation investments, development, rainfall, and everything else. The risk value is not a measure of the change in risk, it is a statement of the current risk, no matter the cause or the contributing factors.

Why Use US Census Tracts? Don’t they change over time? US Census Tracts do periodically change, however, that will not diminish the value of the index. US Census Tracts are areas that can more closely match the scale of typical flood risk reduction projects; watersheds are too large to be informative; and smaller areas would be too complex for our planning work.

Harris County outlined in red, census tracts in blue. Map supplied by Michael Bloom.

The originally proposed FMBI used the population density in the denominator. This, admittedly, would cause issues when comparing index values between large US Census Tracts and small US Census Tracts. To address this issue, the CFRTF and the Infrastructure Resilience Team (IRT) have agreed to proceed with the calculation using just population. This will make the index a per capita value. Prorating investment amounts and risk to each Census Tract can be reasonably accomplished using area ratios or other methods. This will be useful as the CFRTF and IRT work together to prepare the 2050 Flood Resilience Plan.

How Can We Use Information From 1937 When the County is So Different Now? How can this approach work without considering the construction of Lake Houston in 1954, the interstate system, Beltway 8, and the conversion of farmland and prairies into entire communities? The risk value captures all of this. The risk value used in the index reflects the current risk of any part of the county. It will be based on state-of-the-art modeling being conducted as part of the MAAPNext project. The current risk is the current risk, regardless of past changes in the watershed.

Why are we Using the FMBI Formula to Reduce Flood Damage when it Doesn’t Measure Flood Damage? The FMBI is not a tool to directly reduce flood damage and it’s not designed to measure flood damage. The FMBI is a tool to better understand past investment patterns and current risk. The FMBI is proposed to be one of four datasets used to create a baseline conditions heat map. The other three under consideration include current inundation risk, social vulnerability index, and community resources. The baseline conditions heat map will then be used to figure out WHERE flood risk reduction and flood damage reduction projects should be located. 

How Can the FMBI Compare Benefits  without Using Before and After Comparisons? The index is not intended to compare the flood mitigation benefits of the same location at different times. The index is intended to show how different locations across the county at the same time vary when compared to each other. This will help us identify WHERE we have neighborhoods that desperately need help and WHERE we have neighborhoods that don’t.

By Michael Bloom, P.E.

Posted by Bob Rehak on 7/9/22

1775 Days since Hurricane Harvey

Part II will be posted tomorrow. If you have thoughts you would like to share on this subject, please send them via the contact form on this website.

Hurricane Records

Today, I discovered a fascinating 49-page document produced by the National Weather Service, the National Hurricane Center, NOAA and the National Climatic Data Center. It contains hurricane records going back to 1851. It covers the deadliest, costliest and most intense U.S. tropical cyclones and other frequently requested facts. Unfortunately, it only goes through 2010. But the wealth of information on the period it covers more than makes up for that.

Like the Baseball Encyclopedia for Weather Geeks

It’s like the Baseball Encyclopedia for tropical storms…a must read for weather geeks and anyone who wants to impress out-of-town friends. Texas plays a prominent role in this chronicle.

From Page 8. Mainland United States tropical cyclones causing 25 or more deaths, 1851-2010. The black numbers are the ranks of a given storm on Table 2 (e.g. 1 is the deadliest all-time – the Galveston Hurricane of 1900). The colors are the intensity of the tropical cyclone at its maximum impact on the United States.

A look at the lists reveals striking facts. For instance:

  • Fourteen out of the fifteen deadliest hurricanes ranked Category 3 or higher intensity
  • Large death tolls resulted largely from storm surge 10 feet or higher
  • A large portion of the damage in some of the costliest storms resulted from inland floods caused by torrential rains
  • One third of the 30 deadliest hurricanes ranked category 4 or higher
  • Only seven of the 30 deadliest hurricanes occurred between 1985 and 2010 while more than two thirds of the costliest hurricanes occurred during the same period.

A Look Behind the Facts

All costs are adjusted for inflation, so that’s not the major issue. Migration is. 1990 Census data showed that 85% of U.S. coastal residents from Texas to Maine had never experienced a direct hit by a major hurricane. But we have more risk now because more than 50 million people have moved to coastal areas since then.

The study warns, “If warnings are heeded and preparedness plans developed, the death toll can be minimized. However, large property losses are inevitable in the absence of a significant change of attitude, policy, or laws governing building practices (codes and location) near the ocean.”

Filled with Tables, Maps and Insight

One of the most interesting features: maps that show the tracks of record setting storms during the entire period and during each decade.

Amaze your friends with trivia, such as:

  1. Average number of tropical cyclones per year AND how it has varied in different periods.
  2. Years with the most and least hurricanes and landfalls.
  3. Earliest and latest hurricane formations (hint: March 7 and December 31).
  4. Longest- and shortest-lived hurricanes.
  5. Lowest pressure in the Atlantic basin.
  6. Most hurricanes occurring in Atlantic basin at one time.
  7. Number of hurricanes in each month.
  8. Hurricane strikes of various categories by state.
  9. When hurricanes are most likely to strike different areas.
  10. Average return periods for hurricanes in different areas.
  11. Hurricane landfall CYCLES.

That last one really caught my eye.

Hurricanes tend to cluster in certain areas during certain decades!

Biggest Lesson Learned

The study concludes with another warning. “The largest loss of life can occur in the storm surge, so coastal residents should prepare to move away from the water until the hurricane has passed! Unless this message is clearly understood by coastal residents through a thorough and continuing preparedness effort, a future disastrous loss of life is inevitable.”

To read the full study, click here.

This is a genuine work of scholarship dished up in a way that makes it accessible to the general public. That takes some talent! Credits go to Eric Blake and Christopher Landsea of the NHC, and Ethan Gibney of the National Climatic Data Center.

Posted by Bob Rehak on 7/8/22 based on a study by NOAA, NWS and NCDC

1774 Days since Hurricane Harvey

HCFCD Asks for Army Corps Help with Tunnels, Halls Bayou, Addicks/Barker

In June 2022, Harris County Flood Control District (HCFCD) pitched the Army Corps (actually the Assistant Secretary of the Army for Civil Works, referred to as ASA(CW)) for help with three large projects. They included Flood Tunnels; Halls Bayou; and the Addicks and Barker Reservoirs. This leave-behind summarizes the presentation.

Setting the Stage

The presentation begins with a history of the relationship between the Army Corps and HCFCD dating back to 1937. It references past joint projects such as work on the Addicks and Barker Reservoirs; and Brays, White Oak, Little Vince, Cypress, Greens and Sims Bayous.

It also references projects not yet completed such as work on White Oak and Hunting Bayous, and Clear Creek. Finally, it looks forward to future collaboration on Buffalo Bayou, Halls Bayou and a County Wide-Study that “lifts up and empowers our diverse communities to thrive.”

The intro contains graphics that summarize:

  • Damage during Hurricane Harvey
  • Atlas-14 rainfall vs previous estimates
  • Current and Active Army Corps projects
  • A county-wide map of “Recently flooded” (from Harvey) structures overlaid on a social-vulnerability map

The leave-behind then makes three “asks” corresponding with each of the three major projects.

Buffalo Bayou and Tributaries Resiliency Study

The first ask is for help “finding the right solution for Addicks and Barker Reservoirs.” It talks about managing residual risk and liability. Specifically, it asks for support through the completion of the Corps’ Buffalo Bayou and Tributaries Resiliency Study.

It alludes to policies and processes impeding needed progress. Then it says, we must blaze a trail for a new equitable flood risk management paradigm.

An engineer familiar with Buffalo Bayou told me that the study had been cancelled at one time because of a poor Benefit/Cost Ratio. It wasn’t because, as you often hear, that home values were low. It was because land acquisition costs were so high. Possible workarounds: several proposed “innovations” including:

  • Flood tunnels
  • A comprehensive benefits framework that includes more than a strict benefit/cost ratio.
  • “Emphasis on community resiliency, environmental justice, and climate change adaptation.”

The last update of this study on the Corps’ website is from late 2020. The final report has not yet been released. This post from 2020 summarizes the findings of the interim report.

County-Wide Section 203 Study

Section 203 of the Water Resources Development Act was amended to let non-Federal sponsors conduct feasibility studies that serve as the basis for authorization of new water resources projects, such as flood tunnels. But acceptance of the results is at the discretion of the ASA (CW). One objective of the presentation: to get the ASA(CW) to partner Harris County on a County-wide flood risk study.

The county pitched the partnership as:

  • A potential “pilot study for Justice40”
  • Climate change preparedness
  • Empowering vulnerable communities to withstand and recover from flood events.

Justice40 is a Biden initiative, announced within his first few weeks in office. It uses every lever at his disposal “to advance environmental justice and spur economic opportunity for disadvantaged communities. The “40” refers to Biden’s promise to deliver at least 40 percent of the overall benefits from Federal investments in climate and clean energy to disadvantaged communities. One of the priorities: mitigation initiatives that reduce or eliminate the risk of repetitive flooding.

Halls Bayou Section 118 Study

According to the presentation, the Federal government had a project to study flood-risk management on Halls Bayou from 1990 to 2016 when it was “de-authorized.” The county wants to restart it. Section 118 refers to “Pilot programs on the formulation of Corps of Engineers’ projects in … economically disadvantaged communities.”

Harris County wants the Corps to include Halls on its list of ten nationwide pilot studies for such communities. HCFCD points out that Halls has the highest percentage of Low-to-Moderate Income residents of any watershed in the county (71%). Halls has a poverty rate of 28% and a social vulnerability index of 0.85 out of 1.00. Halls also has frequent, severe, repetitive flooding.

At one time, HCFCD cancelled Halls’ Bayou studies because they all came back with Benefit/Cost Ratios below 1.0. That means costs exceeded benefits. HCFCD hopes to restart those in 2022. Section 118 gives the ASA (CW) a way to apply other criteria that compensate for a low BCR in disadvantaged areas.

Posted by Bob Rehak on 7/7/22

1773 Days since Hurricane Harvey

Formula for Allocating Future Flood-Mitigation Funding Deceives

How do you fairly allocate flood-mitigation funds? Voters have argued about that since the day Harris County Commissioners Court redefined the conventional meaning of “equitable” with the first equity formula in 2019. Since then the formula has changed several times to ensure low-to-moderate income (LMI) areas continue to receive the lion’s share of mitigation funding, even as some commissioners claim LMI areas get none.

On 6/28/22, the Harris County Community Resilience Flood Task Force proposed yet another formula for allocating potentially billions of dollars in future flood-mitigation funding. It purports to objectively calculate the benefits received by different areas. But it doesn’t in any conventional sense. And therefore, the results can be deceptively counter-intuitive.

Problems With Formula

The formula shows increased benefit when:

  • Risk remains unchanged.
  • Costs increase.
  • Population decreases.

The formula is…

Benefit = Total Cost/(Population X Risk)

On July 2, 2022, I posted about a variety of issues that affect the validity of this formula. Admittedly, the post got complex. So let me give you two simple examples that dramatize these problems.

In each example below, I’ll hold two of the three variables constant. That makes it easy to see whether “benefit” varies in a predictable direction. And whether that matches what people expect when they hear the word “benefit.”

Cost Example

The value of “10” applied to Risk in each case represents a 10% annual chance of flooding.

If you hold risk and population constant, while increasing cost…

  1. Population = 5000, Risk = 10 and Cost = $100,000, then Benefit = 2
  2. Population = 5000, Risk = 10, and Cost = $1,000,000, then Benefit = 20

…benefit increases by spending more without reducing risk! A taxpayer nightmare!

Population Example

If you hold cost and risk constant, while increasing population…

  1. Population = 2000, Risk = 10, and Cost = $1 million, then Benefit = 50
  2. Population = 5000, Risk = 10, and Cost = $1 million, then Benefit = 20

…benefit decreases by helping more people with the same dollars! Again, counter-intuitive.

Both takeaways are confusing. What is this formula measuring?!

I would argue that, in a flood context, most people strongly associate the word “benefit” with “risk reduction.”

But this formula doesn’t measure risk reduction. And it doesn’t measure efficiency either. It measures per capita investment associated with a certain level of flood risk and calls that “Benefit.”

So, the more people you help with any given sum, the more the benefit goes down. Voila! That makes it look as though the highly populated watersheds (that have received the overwhelming majority of prior investments) have received little benefit. And that may be the point of this formula. It will send even more money to those same areas.

In logic, they call this the fallacy of incomplete evidence – more commonly known as cherry-picking. You cherry pick data that favors your argument and ignore the rest. For instance, consider the image below.

Brays Bayou at Calhoun, photographed May 2021. Note abundance of multi-story apartments.

The total population in some areas includes many people in tall apartment buildings or high-rises. For many of them, flooding may be more inconvenient than financially devastating. Yet the formula assumes all people suffer equally.

The formula provides the appearance of objectivity and fairness. But it masks important information by lumping everything into a single number.

But the proponents of this formula don’t even want to discuss numbers. They want to render the results as heat maps, layered with Social Vulnerability Index, LMI and other data guaranteed to mask and perpetuate the lopsided distribution of flood-mitigation funds.

Omitting Benefits to Structures

By defining Benefit as the cost per person to achieve a certain level of flood risk, the formula omits any benefit to structures. That’s the traditional way to define the benefit of a flood-mitigation project. You measure “the value of damages avoided.” Whether one person lives in a house or two people live there, the cost to protect those people and that home remains the same.

For instance, widening a channel can reduce flood risk for a house. But with the proposed formula, that home and its value no longer count – only the number of people living within it. So, doubling the number of people in a representative home cuts the Benefit of a flood mitigation project in half.

Conclusions

The formula is a vast oversimplification. It omits valuable information such as avoided damages.

It’s also confusing and semantically deceptive in that results vary in counter-intuitive directions.

Finally, as I previously posted, the formula is not valid. It masks several apples-to-oranges comparisons.

Yet the majority of the Community Resilience Flood Task Force proposes using it to help guide (potentially) billions in future flood-mitigation investments. That could hurt taxpayers, flood victims, future bonds and the credibility of local government.

The formula can deceive people into making bad flood-mitigation investments. But in this case, there’s no Securities & Exchange Commission to protect investors. Only the ballot box.

Posted by Bob Rehak on 7/6/22

1772 Days since Hurricane Harvey

Beginning of End for Last of Forest Cove Townhomes

Today, 7/5/22, marked the beginning of the end for the last of the three remaining townhome complexes on Marina Drive in Forest Cove. Demolition began at 4:45 this afternoon on the complex nearest the Forest Cove community center. The job foreman estimates that removal of the two complexes shown below could take a week or more. By then, the third complex nearest the Forest Cove swimming pool should also be ready for demolition. Back in mid-June, Harris County Flood Control scheduled it for demolition on 7/14/22. So by the end of this month, Forest Cove could look very different.

Pictures Taken 7/5/22

The two complexes that started undergoing demolition today. These back up to the new Houston Parks Board Trail that will connect Kingwood with Precinct 3’s Edgewater Park at the NE corner of 59 and the West Fork.

Hurricane Harvey destroyed the townhomes almost five years ago, when approximately 240,000 cubic feet per second of stormwater inundated the homes to the third floors.

The homes became structurally unsound as you can see below.

Destruction wrought by Harvey.

HCFCD began buyouts of the 14 townhome complexes in this area back in 2019. The District completed 80% of the buyouts by February 2020. They expected to complete the remainder by the end of that year. But completing the buyouts took much longer than expected. This story explains why. Basically, HCFCD cannot tear town a complex until it has bought out all units within the complex. And some owners had left the area without forwarding addresses.

First bite into the first of three remaining complexes late this afternoon.
The second bite took out the corner of the structure.
Demolition will resume in the morning.

Harvey destroyed these townhomes so thoroughly that FEMA chose to film a video about the power of Harvey here.

Once prized for their river views, seclusion, and laid-back lifestyle, the remaining townhomes will come down this month and then HCFCD will let the area return to nature. It’s not clear at this time whether the county has plans to extend Edgewater Park this far.

More pictures and news to follow as the project progresses.

Posted by Bob Rehak on 7/5/22

1771 Days since Hurricane Harvey

CWA Exploring Alternate Plan for Adding Lake Houston Dam Gates

Coastal Water Authority (CWA) recently posted minutes from its May 11th board meeting that reveal a possible new direction for adding more flood gates to the Lake Houston Dam. After months of discussing various crest gate alternatives to increase the release capacity of the dam, engineers will now focus on examining two tainter gate alternatives. One would add six tainter gates, the other twelve.

Neither alternative would modify the concrete portion of the spillway, as crest gates would. Black & Veatch, the engineering firm in charge of the project, will explore adding the tainter gates in the earthen embankment to the east of the existing spillway. See below, upper right.

Looking ENE at Lake Houston Dam. Black and Veatch is now exploring adding tainter gates to the earthen portion of the dam in the upper right.

The eastern embankment is a solid earthen area 2800 feet long east of the spillway and existing gates (see upper right of photo above). Water cannot get over it in a storm because it is so much higher than the spillway. By adding various structures in this area, engineers could widen the current spillway capacity, allowing release of more stormwater.

Tainter gates rotate up from a central pivot point. Crest gates rotate down from a bottom hinge, like a piano lid.

Minutes from May CWA Board Meeting

Item IV(B) on Page 3 of the May 11, 2022, minutes states, “…CWA, City of Houston (COH), and Black and Veatch (B&V) met on April 14, 2022. During that meeting the COH requested that an alternate gate location to the east of the existing gate structure be further [emphasis added] evaluated.”

Following the meeting, B&V developed a scope of work to update the gate concepts and construction costs for this area. The COH provided comments and B&V modified its proposal. B&V reportedly began work on the new direction by June 1.

Additional Funding Needed

Each of the new alternatives would require additional funding; neither fit within the existing budget, according to the CWA staff. COH Public Works will pay for the new evaluation.

Wayne Klotz, P.E. and President of the CWA Board, reminded everyone present that COH owns the dam and is the FEMA grantee for this project, while CWA works for and takes direction from COH.

Minutes from the June CWA meeting have not yet been posted. The last post about gates on the COH District E website was almost a year ago on July 8, 2021.

7/4/22 Screen Capture from District E Website.

However, City Council member and Mayor Pro Tem Dave Martin did take questions on the project at an April 2022 community meeting. At the time, Martin expected to have a final answer on gates in a “September-ish” time frame.

Based on costs of the Addicks and Barker dam modifications by the Army Corps, some remain skeptical of any alternative for adding gates to the dam. The reason: budget and the Benefit/Cost Ratio.

Currently, the release capacity of tainter gates on the Lake Conroe Dam is 15X greater than those on the Lake Houston Dam (150,000 cubic feet per second (CFS) vs. 10,000 CFS.)

Concept Studied and Rejected Once Already

Adding gates to the eastern embankment was one of the original concepts evaluated. (See Column 5, Offsite Alternative #2, Column 5, Page 4.) But engineers focused on adding crest gates instead, largely because the total estimated costs for adding tainter gates at that time exceeded $90 million for a $50 million budget. However, the Army Corps also had environmental concerns about adding gates to the eastern embankment.

FEMA initially gave the City three years to complete the project (18 months for engineering and 18 for construction). Engineering began in April 2020.

No other details about May’s change in direction have been released to my knowledge.

Posted by Bob Rehak on 7/4/2022 based on minutes from the May CWA Board meeting

1770 Days since Hurricane Harvey

Questionable Validity of Flood-Mitigation Equity Formula

The results of an apparently invalid flood-mitigation equity formula could be used to steer billions of dollars in future flood-mitigation funding. Multiple data quality and collection issues may compound errors and the formula itself sometimes renders inconsistent, counter-intuitive results.

In the 6/28/22 Harris County Commissioners Court meeting, the Community Flood Resilience Task Force presented its first annual report. The report contains a lengthy discussion of a flood-mitigation equity formula developed by several Task Force members to “objectively” compare the “equity” of flood-mitigation investments (project costs). See the appendix starting on Page XVI and ending on Page XX.

The attempt to create objective comparisons between investments in different areas is well intentioned. However, I fear the proposed formula will create the appearance of objectivity while skewing data and producing misleading results. Here’s why.

The Formula

The formula is…

Flood Mitigation Benefits Index = Total Cost to Date/(Population Density X Risk)

…where…

  • Population Density is the number of people per square mile, calculated at the US Census Tract level.
  • Flood Risk is the current annual chance of inundation. For instance, a 1% chance = 1. Or a 10% chance = 10, etc.
  • Total Cost to Date shows cumulative dollars spent on flood-risk-reduction projects (construction only, adjusted for inflation) over the longest time period for which records are available, calculated at the US Census Tract level.

The report claims that a higher index means people have received more investment and therefore have less flood risk (i.e., more benefit). Conversely, a low index indicates less investment, more risk and less benefit.

The focus on census tracts is designed to make the data more granular than watersheds. Flood risk estimates will be averaged across the census tract and updated after MAAPnext data becomes available.

Here are several issues I have articulated to the Task Force.

Data Collection and Quality Issues

  1. Calculating only construction costs excludes other capital improvement costs such as engineering, design and right-of-way acquisition. Since 2000, construction costs have comprised only 40% of capital improvement costs. See below. And those costs don’t even reflect maintenance and repairs, which are crucial in reducing flooding.
All Flood Control and partner spending on all capital improvement projects from 1/1/2000 through the end of Q3 2021. Data obtained via FOIA Request from HCFCD.

2. According to the report, costs factored into the formula will include those from City of Houston projects and Harris County Flood Control projects. But they don’t include other municipalities’. There are at least 33 other cities in the County. The formula will reflect street-flooding risk, but not all spending to reduce that risk.

3. Likewise, it’s not clear whether the risk reflects pre- or post-mitigation spending, or both. Every time I ask about that, I get silence not an answer. Flood Control has spent more than $1.5 billion on flood mitigation since Harvey, while simultaneously developing new flood maps. Will the numerator of the formula sometimes reflect that investment but not the denominator?

4. Readily available digital spending data goes back only to 2000. But the Task Force committee chairman insists on getting data going back to the start of the Flood Control District – in 1937. If those records still exist, they will radically skew historical comparisons between watersheds, many of which were farms or forests until much more recently.

5. Flood risk depends on more than just mitigation investments. It’s a shifting target that has changed multiple times since 1937 as our understanding of rainfall probabilities has improved, and as different jurisdictions recognize that risk at different times. Flood risk also depends on upstream growth. That has been exponential. In the 2020 Census, Harris County had 4.7 million people. But in the 1930 Census, Harris County had only 359,328 – one thirteenth of today’s population, and presumably one thirteenth of the census tracts. So, attributing all change in risk to investment is fallacious.

6. Many of the census tracts have changed since the 1930s. Census tract boundaries are only “relatively” permanent. They often change based on Census results. For instance, when a census tract’s internal population grows over 8,000 persons, it may split into two or more smaller census tracts. Also, census tract boundaries may cross watershed boundaries. Major thoroughfares usually define census tract boundaries, not the direction of flowing water.

7. HCFCD has said they do not collect spending data by census tract. They calculate how much it costs to remove structures from the floodplain. So census tract data will have to be estimated manually – something that makes data-quality experts nervous.

8. Many neighborhoods outside Beltway 8 didn’t exist back in the 1930s. Beltway 8 didn’t even exist then. Nor did Lake Houston; the City began impounding water only in 1954.

9. The formula – designed to reduce flood damage – doesn’t measure flood damage.

10. So much data in this study won’t be directly comparable that I worry the authors won’t be able to highlight areas worthy of future investment. Final results will include compounded error on multiple levels. It doesn’t compare apples to apples; it compares apples to oranges, bananas, blueberries, cherries, strawberries, coconuts, Monty Python’s elderberries and more.

Questionable Validity

In fairness, I’m sure the final report, when it becomes available, would disclose these problems in an appendix or footnotes. But how many people dig into those? And who will “peer review” this study?

I have worked with market research my entire career and know the painstaking extents to which researchers go to ensure validity of their studies.

Validity has to do with accuracy. Are you really measuring what you purport to measure? For instance, is flood risk influenced ONLY by mitigation investment? Or is it ALSO influenced by other factors, such as:

The answer is a resounding YES to all those questions and more.

Good research studies typically measure the impact of one variable on another variable. For instance, in Harris County, what was the death rate last year among adults over 50 who contracted Covid among vaccinated and unvaccinated groups? Researchers carefully match the two groups being studied for factors such as randomness of subject recruitment, age, living situation, and history of other diseases. There is only one variable: vaccination. That way, they can tell whether the death rate varies among vaccinated people.

But the Flood Mitigation Benefit Index wasn’t designed with that kind of rigor. For example:

While purporting to compare ‘benefits’ of flood-mitigation to different areas, it doesn’t even employ pre- or post-measurements.

Further reducing comparability of results during the period studied:

  • Census tracts changed.
  • Population density changed.
  • Building codes changed.
  • Channels filled up with sediment, but maintenance won’t be measured.
  • AND the data does not measure street-flooding mitigation investments in almost HALF the county.

Because the flood-equity formula doesn’t control for such factors, we won’t know what caused variation in the results.

Formula Produces Inconsistent Results

The flood-equity formula does not even yield results that vary intuitively. For instance, when you hold population density and flood risk constant, but increase investment, the benefit goes up.

  • Example A: If Density = 5000, Risk = 10 and Investment = $100,000, then Benefit Index = 2
  • Example B: If Density = 5000, Risk = 10, and Investment = $1 million, then Benefit Index = 20

So, spending more money to get the same results increases benefits? Shouldn’t it be the opposite?

That’s both depressing and confusing. You spend 10X the money; flood risk remains the same; and the “benefit” increases!!!???

You would think spending less money to achieve identical results would be more beneficial. It certainly is for taxpayers.

Although the Task Force won’t admit it, the formula is really trying to prove “historical disinvestment,” a claim tossed around frequently in Task-Force and Commissioners Court meetings without data to back it up.

But if the goal is to protect the most people from future flooding, why not just invest in projects where the highest risk remains for the greatest number of people? Both of those are simple, unambiguous direct measurements. But those might not produce the results that the authors of this formula hope to get.

I believe we should look forward, not back, with our flood-mitigation dollars. We can’t change the past…whatever it was. We can only affect the future by what we do today.

Posted by Bob Rehak on 7/3/2022

1769 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.

Progress Report: Woodridge Village Excavation and Removal Contract

As of the end of June 2022, Harris County Flood Control District (HCFCD) had removed 42,483 cubic yards of dirt from the Woodridge Village property in Montgomery County. The dirt is part of an excavation and removal (E&R) contract that allows removal of up to 500,000 cubic yards. That amount would double the floodwater detention capacity on the site and help reduce the risk of flooding in Elm Grove and North Kingwood Forest along Taylor Gully. Heavy rains in May and September of 2019 flooded approximately 600 homes in the area.

History of Project

Harris County purchased Woodridge with the City of Houston from Perry Homes in February 2021. At the time of purchase, the site had enough detention capacity to meet pre-Atlas 14 requirements in Montgomery County. But Atlas-14 requirements call for about 40% more. Hence the need to increase floodwater detention capacity.

Harris County Commissioners Court approved the contract with Sprint Sand and Clay on July 20, 2021. It obligates Sprint to remove at least 5000 cubic yards per month. Excavation started on January 27, 2022. Five months later, Sprint has removed 42,483 cubic yards, 17,000 cubic yards more than the minimum.

Sprint will excavate within red area.

Chronological Excavation Photos

Woodridge Village Before e&r contract
Looking NE at Woodridge Village before start.
Woodridge Village E&R contract
Start of E&R Contract on January 27, 2022. Tree Line on right is the Montgomery/Harris County Line. Harris is on right.
January 29, 2022
February 27, 2022

Woodridge Village E&R
March 28, 2022
April 30, 2022
May 22, 2022
June 13, 2022, 41,174 cubic yards of material removed from the site
June 30, 2022, 42,483 cubic yards of material removed

Excavation & Removal Contract

E&R contracts provide a head start on construction of detention basins before completion of their final design.

Sprint has agreed to remove up to half a million cubic yards of soil for only $1000. But it gets to sell the soil for a profit on the open market. This provides significant savings to taxpayers by minimizing trucking and disposal fees.

By contract, Sprint has up to 36 months. If Sprint continues removing dirt at the rate of about 8,000 cubic yards per month, they should remove another 248,000 cubic yards before the end of the contract term.

With the dirt already removed, that would only put them at 290,00 cubic yards at the end of three years. So at some point, Sprint will have to sprint to catch up if they want to remove all 500,00 cubic yards.

Future of Woodridge Village

The rate of removal will ultimately depend on developments in the housing market. The latest report by the Census Bureau shows housing starts in May 2022 were down 7% from April 2022, but still 0.2% ahead of May 2021.

An engineering study currently underway includes the Woodridge property. HCFCD has the flexibility to change the E&R contract if necessary to accommodate any design requirements that emerge from the study.

Community engagement should be scheduled soon to gather input from area residents on the proposed project and to present project alternatives.

Posted by Bob Rehak on 7/1/2022

1767 Days since Hurricane Harvey