Tag Archive for: First Street Foundation

How Flood-Risk Information Affects Real-Estate Sales

A new study of “climate migration” by the First Street Foundation looks at how flood-risk information affects real-estate sales. It found that the availability of high-resolution data affects home buying, sometimes in surprising ways.

The foundation’s mission is to make climate-risk data accessible, easy to understand and actionable for individuals, governments, and industry. It estimates different types of climate risk from flooding to fire, wind, drought and more – from the state to the county, zip code and street-address levels.

First Street’s most recent study is called “Climate Abandonment Areas.” But most of the important findings have to do with flooding. First Street published the study in the journal Nature-Communications on December 18, 2023.

Cover photo from First Street Foundation Climate Abandonment Areas Study. No credit listed.

Key Findings

Among First Street’s key findings:

  • Flood risk is a house-by-house issue, not a state-by-state issue. People may still move to states with high flood risk, but increasingly they’re using flood data to avoid risky neighborhoods and properties.
  • In the U.S., 34.5% of the population and 41.9% of the housing stock have been impacted by flooding.
  • Nationally, 7.4% of census blocks are beginning to lose population because of flood risk. Within them, 3.2 million people (35.5% of the decline) moved away because of flooding between 2000 and 2020.
  • Dr. Jeremy Porter, Head of Climate Implications Research at First Street, said “the downstream implications of this are massive and impact property values, neighborhood composition, and commercial viability both positively and negatively.” 
  • As people leave to avoid flood risk, property values decline, affecting cities’ tax bases. Further, the population left behind tends to be older and poorer.
  • The study defines 9% of the census blocks in Harris County as “Climate Abandonment Areas.” It further claims Houston has passed a tipping point where more people are moving out than in, it says, because of flood risk.
  • Many areas have “pull factors” such as jobs that offset the number of people leaving. But their growth would be even higher if flood risk were lower. Said another way, areas with high flood risk grow more slowly if they grow at all.
  • Population losses are greatest among areas that flood frequently, i.e., a 5-year flood risk.
  • High-resolution information about flooding progressively reduced consideration of homes with high risk by 24.6% after 9-weeks of study.

Confusing Definitions, Frames of Reference

While this purports to be a study about how “climate change” affects “climate migration,” the numerous counter-intuitive climate-change references constantly obscure the findings.

For instance, the authors start out talking about wildfires, severe storms, flooding, drought, tropical storms and winter storms. But then they talk primarily about flooding in relation to people moving a matter of city blocks.

As a consequence, it gets confusing. “It appears that they are trying to fit a trend to the climate change agenda,” said one of the leading hydrologists in Texas.

One must read carefully to determine the frame of reference for each claim.

Good News, Bad News

The good news is that First Street data shows people seem to be paying more attention to flood risk when they purchase homes – assuming that good data is available.

The bad news is that good flood-risk data is often not available. Across our region, for instance, many areas remain unstudied. And recent data often remains unreported, i.e., in Harris County.

In the meantime, developers continue to build in floodplains. And new developments often don’t yet have listed addresses. So it’s hard to for homebuyers to estimate risk – even when using First Street’s models.

The hydrologist mentioned above felt First Street overcomplicated the issue. “This isn’t about climate change; it is about common sense. People built in places they shouldn’t have built decades ago and after enough disasters, people have had enough. They are moving. Floods have happened since the dawn of time and certainly before ‘climate change.’ Common sense tells you that people move when they have been hit hard and often enough.” 

Posted by Bob Rehak on 12/19/2023

2303 Days since Hurricane Harvey

New Data Suggests Houston’s Expected 100-Year Flood Is More Likely to Happen Every 8 to 23 Years

First Street Foundation, a non-profit risk-research group, estimates (based on what it says are “well known” Atlas-14 flaws) that a so-called 100-year flood event in Houston could likely happen every 8 to 23 years.

NOAA’s Atlas 14, a massive, years-long effort, which hasn’t even been fully implemented yet, may already be seriously out of date according to First Street.

As a result, First Street claims the design standards for infrastructure projects based on erroneous Atlas-14 data are likely to fail. Trillions of infrastructure investment dollars hang in the balance.

NOAA Replacing Atlas 14 with Atlas 15 Already

NOAA expects to release its latest Atlas-15 rainfall probability statistics for the U.S. sometime in 2027. Like Atlas 14 below, they will contain probabilities for every location in the country – for durations ranging from 5 minutes to 60 days and recurrence intervals from 1 year to 1000 years.

atlas 14 rainfall probabilities
Atlas 14 Probabilities for the North Houston area.

Moreover, for the first time ever, Atlas-15 probabilities will come in two flavors: with and without estimates for the impact of climate change.

First Street Foundation, a non-profit research and technology group, specializes in environmental risk assessment. They position their system, RiskFactor.com, as a stopgap until NOAA releases Atlas 15.

Time Lags Cause Confusion, Create Danger

FEMA still has not released flood maps based on the Atlas-14 probabilities above. The MAAPNext Group within Harris County Flood Control District has been working on those since Harvey. MAAPNext’s latest timeline (below) shows that FEMA may not make Atlas-14-based flood maps official for another 3+ years.

Engineers and government officials use this data when designing new subdivisions, industrial facilities, bridges, highways and other infrastructure.

For instance, they need to know, how high the bridge must be to let water flow under it during a flood to avoid catastrophes like the one below.

I-69 repairs
Old data led TxDoT to inadequately design the I-69 bridge over the San Jacinto West Fork. Repairs took more than a year after Harvey to complete while residents endured massive traffic jams.

Atlas 15 Underway Before Atlas 14 Implemented

A copyrighted article in the New York Times this morning by Raymond Zhong was titled “Intensifying Rains Pose Hidden Flood Risks Across the U.S.” In it, Mr. Zhong claims that new calculations show hazardous storms can dump significantly more water than previously believed.

“One in nine residents of the lower 48 states, largely in populous regions including the Mid-Atlantic and the Texas Gulf Coast, is at significant risk of downpours that deliver at least 50 percent more rain per hour than local pipes, channels and culverts might be designed to drain,” says Zhong.

Compounding the problem, “NOAA’s estimates are ‘the floor, not a ceiling,'” said Zhong, quoting Abdullah Hasan, a White House spokesman.

“That means millions of homeowners might be making decisions with an incomplete understanding of the true physical and financial risks they face,” said Zhong.

145,000 Houston Homes and Billions in Infrastructure Caught in Time Lag

Zhong quoted First Street Foundation, which said that in Houston alone, as many as 145,000 homes may be in the 100-year flood zone, but that they are not shown that way in current FEMA flood maps.

To put Atlas 15 and its climate change corrections into perspective…

First Street estimates that in Houston, what we currently think of as a 100-year flood may actually be an 8- to 23-year flood.

First Street Foundation Press Release

All this comes as the nation gears up to spend more than $1.2 trillion dollars on infrastructure which Congress and President Biden approved in 2021.

And that $1.2 trillion doesn’t even include the money homebuyers spend each year. About 30% of all household income in the U.S. goes toward housing. And the average American moves once every seven years.

That means virtually everyone is likely not making home-buying decisions based on the most current (accurate) flood probabilities. By the time FEMA releases Harvey-based Atlas-14 flood maps, Atlas-15 revisions will already be available to a select few.

While the Association of State Flood Plain Managers finds First Street data useful, it emailed a report at the close of business today about First Street. The report says that “ASFPM has and will continue to support NOAA’s work on Atlas 14 and 15, which will remain the gold standard within our profession.”

Problems Caused By Lack of Timely Updates

The vast majority of developers, homebuilders and engineers are ethical. But some less scrupulous developers can exploit confusion caused by irregular update policies.

Likewise, engineers who designed a bridge to one set of specs, may find their work out-dated before construction starts. What are the ethical obligations in a case like that?

Just this year, we’ve seen numerous instances of developers trying to get their plans grandfathered under pre-Atlas-14 regulations even as the U.S. moves toward Atlas 15. Little wonder that when a flood happens, few can explain where the system went wrong.

“The fact that the Nation will not have the most accurate estimates of extreme precipitation likelihoods available at the time of the design of these projects means that many of them will be out of date on the day they are opened to the public,” said Matthew Eby, Founder and Executive Director of First Street Foundation.

Governments at all levels need to work better together to shorten the data supply chain. Doing so could save Americans trillions of dollars.

Posted by Bob Rehak on 6/26/2023

2127 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.