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:
Average number of tropical cyclones per year AND how it has varied in different periods.
Years with the most and least hurricanes and landfalls.
Earliest and latest hurricane formations (hint: March 7 and December 31).
Longest- and shortest-lived hurricanes.
Lowest pressure in the Atlantic basin.
Most hurricanes occurring in Atlantic basin at one time.
Number of hurricanes in each month.
Hurricane strikes of various categories by state.
When hurricanes are most likely to strike different areas.
Average return periods for hurricanes in different areas.
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.”
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 7/8/22based on a study by NOAA, NWS and NCDC
1774 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/07/20220708-Screen-Shot-2022-07-08-at-7.11.56-PM.jpg?fit=1200%2C753&ssl=17531200adminadmin2022-07-08 19:27:262022-07-08 19:32:28Hurricane Records
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
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/07/20220707-Screen-Shot-2022-07-07-at-12.32.19-PM-2.jpg?fit=1200%2C737&ssl=17371200adminadmin2022-07-07 18:31:582022-07-07 18:33:16HCFCD Asks for Army Corps Help with Tunnels, Halls Bayou, Addicks/Barker
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.
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 youhold risk and population constant, while increasing cost…
Population = 5000, Risk = 10 and Cost = $100,000, then Benefit = 2
Population = 5000, Risk = 10, and Cost = $1,000,000, then Benefit = 20
…benefit increases by spending morewithoutreducing risk! A taxpayer nightmare!
Population Example
If you hold cost and risk constant, while increasing population…
Population = 2000, Risk = 10, and Cost = $1 million, then Benefit = 50
Population = 5000, Risk = 10, and Cost = $1 million, then Benefit = 20
…benefit decreases by helpingmore 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.
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
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/07/20210520-RJR_7082.jpg?fit=1200%2C800&ssl=18001200adminadmin2022-07-06 20:47:392022-07-07 08:48:23Formula for Allocating Future Flood-Mitigation Funding Deceives
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.
A look at the lists reveals striking facts. For instance:
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:
That last one really caught my eye.
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:
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:
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:
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:
The formula is…
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…
…benefit increases by spending more without reducing risk! A taxpayer nightmare!
Population Example
If you hold cost and risk constant, while increasing population…
…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.
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