New study targets past flooding as key to helping property owners assess climate threats
The study, published Monday in the journal Earth's Future, found that 43% of flooded buildings in North Carolina between 1996 and 2020 were located outside the Federal Emergency Management Agency's Special Flood Hazard Area — areas that FEMA projects have a 1% risk of flooding in a given year.
The findings could help more communities get a better handle on their flood risk and flood insurance needs, experts and authors of the study said. Flood insurance has become increasingly hard to get as some companies increase the price of policies or step back from insuring homes in certain markets due to more frequent and severe weather. That has left property owners more vulnerable.
Experts told NBC News that with access to the right data sources, databases like the one described in the study could be developed nationwide.
FEMA's maps are the main source nationally to identify flood-prone areas and what structures need to be insured. But experts say the system is outdated and has low resolution. The 100-year flood plain projection doesn't paint a complete picture of what areas are likely to flood. And climate change has rendered previously authoritative weather and climate projections less reliable, the authors noted.
The study's use of address-level data allowed the researchers to pinpoint specific buildings that had flooded more than once. That information could help property owners know whether they should be purchasing flood insurance even outside of FEMA's flood hazard zones, experts said. In the U.S., 99% of counties have flooded at least once but only 4% of homeowners have flood insurance, according to FEMA.
'More information about where it has flooded in the past could help people make different decisions,' said Helena Margaret Garcia, the lead author of the study and a doctoral student at the University of North Carolina-Chapel Hill.
FEMA and the National Flood Insurance Program did not return requests for comment.
FEMA is currently in the process of redeveloping its flood mapping system, through an initiative called the Future of Flood Risk Data, that it says will provide a more comprehensive look at flood hazards and risks in the country using more efficient, accurate and consistent technology.
As the planet warms, heavier rainfall is becoming more common because hotter air can hold more moisture, which later falls as rain. Climate change is also leading to a rise in global sea levels, which has made coastal and even some inland areas more vulnerable to flooding. Hurricane Helene, the third-deadliest hurricane of the modern era, caused severe flooding in mountainous areas in the middle of North Carolina. Damage totaled more than $78 billion, according to the National Oceanic and Atmospheric Administration.
Severe rainfall has caused flash floods to rip through towns across the U.S. in the last two weeks, most recently on Monday in New Jersey and New York City. Extreme floods resulted in at least six deaths in North Carolina and more than 100 deaths in Texas. Flash floods are the top storm-related killer in the U.S. resulting in an average of 125 deaths per year in the last few decades, according to the National Weather Service
A North Carolina climatologist said warmer ocean waters, which also feed storms, could have been a factor in fueling last week's Tropical Storm Chantal, which broke rainfall and river-crest records in the state.
With the changing climate, having access to up-to-date maps is crucial, experts say.
For the study, researchers mapped 78 flood events between 1996 and 2020 using data from the National Flood Insurance Program — the FEMA program through which property owners can purchase insurance for potential flood-related losses. They also used emergency service requests and 'volunteered geographic information,' which they acquired through social media posts, to create what they describe as a 'first of its kind' database. Data on past floods is often difficult for the general public to access, which can make it challenging for homeowners to know whether their property has previously flooded, experts said.
Garcia said researchers can use the same methods from the study to create similar historical maps for regions across the nation to help officials identify areas in their state they may not have previously thought of as a flood risk.
While the study found that only 20,000 of the 90,000 buildings flooded more than once — more than double the number of buildings that filed NFIP claims — authors of the study are working on research to quantify its human impact. Some are looking at health outcomes, including how a flood might interrupt people's health care, and others looking into the quantity of displacement due to the repetitive flooding, Garcia said.
Antonia Sebastian, an assistant professor in the department of geological sciences at UNC-Chapel Hill, said the study aims to create a 'comprehensive record of past flooding' by gathering data on flood events that don't make the biggest headlines but still have an impact on homeowners.
'Places that have flooded before will flood again. It's just a matter of time,' Sebastian said. 'And those are all risky places.'
Chad Berginnis, the executive director of the Association of Flood Plain Managers who wasn't involved in the study, said FEMA's maps are designed to implement the NFIP by determining what areas have to purchase flood insurance, using the 100-year flood plain as a guide. He said the study's analysis of historical flooding highlights that officials may need to require flood insurance in areas outside of FEMA's flood hazard zone.
'FEMA flood maps are a starting point and not an end point,' Berginnis said. 'They will show you one kind of flood risk, but if you want a total perception of flood risk, one of the things you got to do is find historical flood information.'
He said replicating similar database models as the one described in the study in other local areas could help flood plain managers increase awareness among their communities about who is at risk of flooding by pinpointing where it has occurred previously.
'Just given the flood history of [the Guadalupe River], and having a daughter of the age that's going to camps too, I mean, this is really hitting home to me. You know, how is it that we, that societally, we're not comprehending that these same locations can also be very risky areas and not either demanding or finding out a little bit more about it. So, I think clearly we don't have enough awareness of flood risks.'
June Choi, a doctoral student in earth system science at Stanford University who was not part of the study, said the finding that many flooded buildings were located outside of at-risk areas designated by FEMA's flood maps is likely the case across all states. The new database may be limited because it doesn't factor in how building density changes over time. But its use of historical records and address-specific data still make it a valuable resource for assessing future flood risk, she said.
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NBC News
7 hours ago
- NBC News
New study targets past flooding as key to helping property owners assess climate threats
The number of structures at risk of flooding in the United States could be higher than previously thought, according to a study published Monday. The study, published Monday in the journal Earth's Future, found that 43% of flooded buildings in North Carolina between 1996 and 2020 were located outside the Federal Emergency Management Agency's Special Flood Hazard Area — areas that FEMA projects have a 1% risk of flooding in a given year. The findings could help more communities get a better handle on their flood risk and flood insurance needs, experts and authors of the study said. Flood insurance has become increasingly hard to get as some companies increase the price of policies or step back from insuring homes in certain markets due to more frequent and severe weather. That has left property owners more vulnerable. Experts told NBC News that with access to the right data sources, databases like the one described in the study could be developed nationwide. FEMA's maps are the main source nationally to identify flood-prone areas and what structures need to be insured. But experts say the system is outdated and has low resolution. The 100-year flood plain projection doesn't paint a complete picture of what areas are likely to flood. And climate change has rendered previously authoritative weather and climate projections less reliable, the authors noted. The study's use of address-level data allowed the researchers to pinpoint specific buildings that had flooded more than once. That information could help property owners know whether they should be purchasing flood insurance even outside of FEMA's flood hazard zones, experts said. In the U.S., 99% of counties have flooded at least once but only 4% of homeowners have flood insurance, according to FEMA. 'More information about where it has flooded in the past could help people make different decisions,' said Helena Margaret Garcia, the lead author of the study and a doctoral student at the University of North Carolina-Chapel Hill. FEMA and the National Flood Insurance Program did not return requests for comment. FEMA is currently in the process of redeveloping its flood mapping system, through an initiative called the Future of Flood Risk Data, that it says will provide a more comprehensive look at flood hazards and risks in the country using more efficient, accurate and consistent technology. As the planet warms, heavier rainfall is becoming more common because hotter air can hold more moisture, which later falls as rain. Climate change is also leading to a rise in global sea levels, which has made coastal and even some inland areas more vulnerable to flooding. Hurricane Helene, the third-deadliest hurricane of the modern era, caused severe flooding in mountainous areas in the middle of North Carolina. Damage totaled more than $78 billion, according to the National Oceanic and Atmospheric Administration. Severe rainfall has caused flash floods to rip through towns across the U.S. in the last two weeks, most recently on Monday in New Jersey and New York City. Extreme floods resulted in at least six deaths in North Carolina and more than 100 deaths in Texas. Flash floods are the top storm-related killer in the U.S. resulting in an average of 125 deaths per year in the last few decades, according to the National Weather Service A North Carolina climatologist said warmer ocean waters, which also feed storms, could have been a factor in fueling last week's Tropical Storm Chantal, which broke rainfall and river-crest records in the state. With the changing climate, having access to up-to-date maps is crucial, experts say. For the study, researchers mapped 78 flood events between 1996 and 2020 using data from the National Flood Insurance Program — the FEMA program through which property owners can purchase insurance for potential flood-related losses. They also used emergency service requests and 'volunteered geographic information,' which they acquired through social media posts, to create what they describe as a 'first of its kind' database. Data on past floods is often difficult for the general public to access, which can make it challenging for homeowners to know whether their property has previously flooded, experts said. Garcia said researchers can use the same methods from the study to create similar historical maps for regions across the nation to help officials identify areas in their state they may not have previously thought of as a flood risk. While the study found that only 20,000 of the 90,000 buildings flooded more than once — more than double the number of buildings that filed NFIP claims — authors of the study are working on research to quantify its human impact. Some are looking at health outcomes, including how a flood might interrupt people's health care, and others looking into the quantity of displacement due to the repetitive flooding, Garcia said. Antonia Sebastian, an assistant professor in the department of geological sciences at UNC-Chapel Hill, said the study aims to create a 'comprehensive record of past flooding' by gathering data on flood events that don't make the biggest headlines but still have an impact on homeowners. 'Places that have flooded before will flood again. It's just a matter of time,' Sebastian said. 'And those are all risky places.' Chad Berginnis, the executive director of the Association of Flood Plain Managers who wasn't involved in the study, said FEMA's maps are designed to implement the NFIP by determining what areas have to purchase flood insurance, using the 100-year flood plain as a guide. He said the study's analysis of historical flooding highlights that officials may need to require flood insurance in areas outside of FEMA's flood hazard zone. 'FEMA flood maps are a starting point and not an end point,' Berginnis said. 'They will show you one kind of flood risk, but if you want a total perception of flood risk, one of the things you got to do is find historical flood information.' He said replicating similar database models as the one described in the study in other local areas could help flood plain managers increase awareness among their communities about who is at risk of flooding by pinpointing where it has occurred previously. 'Just given the flood history of [the Guadalupe River], and having a daughter of the age that's going to camps too, I mean, this is really hitting home to me. You know, how is it that we, that societally, we're not comprehending that these same locations can also be very risky areas and not either demanding or finding out a little bit more about it. So, I think clearly we don't have enough awareness of flood risks.' June Choi, a doctoral student in earth system science at Stanford University who was not part of the study, said the finding that many flooded buildings were located outside of at-risk areas designated by FEMA's flood maps is likely the case across all states. The new database may be limited because it doesn't factor in how building density changes over time. But its use of historical records and address-specific data still make it a valuable resource for assessing future flood risk, she said.
Daily Mail
4 days ago
- Daily Mail
Scientists issue chilling warning over 'doomsday tsunami' likely to hit parts of the U.S. by 2100
A doomsday tsunami is likely to strike the US in the near future, according to new research led by researchers at Virginia Tech. The study, published in the Proceedings Of The National Academy Of Sciences, found that a devastating earthquake along the Cascadia Subduction Zone (CSZ) in America's Pacific Northwest is almost assured to take place by 2100, with a 37 per cent chance it'll happen at any point in the next 50 years. If an earthquake between 8.0 and 9.0 in magnitude struck today, scientists warn that a 100-foot mega tsunami would wipe out most of the West Coast, as the coastline would drop by almost eight feet instantaneously. Doomsday: Scientists say a tsunami could hit U.S. as massive earthquake is due by 2100 (pictured: aftermath of the 9.0 quake that struck Japan in 2011) The CSZ is a nearly 700-mile-long fault line off the west coast of North America where one tectonic plate, the Juan de Fuca Plate slides beneath another, the North American Plate. It stretches from northern Vancouver Island in Canada to the southern half of the US West Coast, running along the coasts of Washington, Oregon, and California. The Federal Emergency Management Agency (FEMA) estimated that there would be 5,800 deaths from a CSZ earthquake alone and another 8,000 due to the mega tsunami it would unleash. Professor Tina Dura, the lead author of the study, said: 'This is going to be a very catastrophic event for the US, for sure. The tsunami is going to come in, and it's going to be devastating.' Danger zone: The Cascadia zone, which sits under Washington, Oregon, and northern California, is said to be 'overdue' for another major earthquake. The last one struck in 1700 By 2100, climate change is predicted to raise sea levels by as much as two feet. If the Cascadia Subduction Zone doesn't suffer another mega earthquake until then, it will likely amplify the devastation and flooding beyond the damage expected in 2025. The 2022 emergency report from FEMA projected that there would be more than 100,000 people injured and over 618,000 buildings damaged or destroyed during the next major CSZ earthquake. That damage would include more than 2,000 schools and 100 critical facilities along the West Coast, costing the country more than $134billion. Disastrous: If the CSZ ruptured, it could cause a magnitude-9 earthquake throughout the region. The darker areas mark the areas that would receive the most damage, extending inland, where the devastation would be more moderate The new study also predicted that the West Coast would be reshaped for centuries. The earthquake and mega tsunami would radically expand 100-year floodplains in Washington, Oregon, and California by as much as 115 square miles. Floodplains are areas expected to suffer historic flooding at least once every 100 years. If those regions suddenly expanded by more than 100 miles, more homes, roads, and local infrastructure would fall into dangerous flood zones. However, in the worst-case scenarios where subsidence (sinking of the ground) is at its highest, the researchers estimated that their flood zone predictions could more than double. 'After the tsunami comes and eventually recedes, the land is going to persist at lower levels,' Dura told BBC Science Focus. 'That floodplain footprint is going to be altered for decades or even centuries.' The Cascadia Subduction Zone is becoming a major area of concern now because of the growing amount of time that's passed since its last major seismic event. The last major earthquake struck on January 26, 1700. Historians and scientists estimate that it was a magnitude 9.0 earthquake which unleashed a mega tsunami that destroyed the village of Pachena Bay in British Columbia. Records of the event show that waves up to 100 feet high struck just 30 minutes after the quake, leaving no survivors. Scientists have estimated that the CSZ builds up into a major earthquake every 400 to 600 years, meaning it's already been 325 years since the last cataclysmic event. 'You can imagine, during the next earthquake, when the land drops down, you're going to suddenly have to contend with multiple centuries of equivalent sea level rise in minutes,' Dura warned.
Metro
5 days ago
- Metro
'Doomsday' 100-foot mega tsunami likely to hit the US at any moment
Scientists are warning that a 100-foot, Doomsday-style mega tsunami is primed to hit the US West Coast at any moment – and likely within 50 years. On top of that, experts say that the sooner the tsunami hits, the better. The natural disaster threat stems from the Cascadia Subduction Zone, which is a nearly 700-mile fault line from northern California to British Columbia, that has not had much movement in 300 years. That means that the zone is due for a major earthquake, and its effects are predicted to be worse as time goes on. 'By 2100, when climate-driven sea-level rise will compound the hazard, a great earthquake could expand floodplains… more than tripling the flooding exposure of residents, structures, and roads under the high subsidence scenario compared to the 2023 floodplain,' states a recent article published in the Proceedings of the National Academy of Sciences. There is a 37% chance of a quake in the Pacific Northwest happening in the next half-century, and one is almost guaranteed to hit by 2100, according to the study published in April. 'This is going to be a very catastrophic event for the US, for sure,' the study's lead author, Tina Dura, told BBC Science Focus. 'The tsunami is going to come in, and it's going to be devastating.' A quake of magnitude 8.0 to 9.0 could create a 100-foot tsunami capable of crushing eight feet of the coastline and wiping out much of the West Coast. 'After the tsunami comes and eventually recedes, the land is going to persist at lower levels,' Dura said. 'That floodplain footprint is going to be altered for decades or even centuries.' More Trending Such a quake could cause 5,800 deaths, and the resulting tsunami could claim another 8,000 lives, according to the Federal Emergency Management Agency, the nation's agency helping people before, during and after disasters. The coasts of California, Oregon, and Washington, up to northern Vancouver Island in Canada, are under the threat. The last massive earthquake, magnitude 9.0, hit in January 1700 and spurred a tsunami that took out the village of Pachena Bay in British Columbia. 'This study underscores the need to consider combined earthquake and climate impacts in planning for coastal resilience at the Cascadia subduction zone and globally,' states the article. Get in touch with our news team by emailing us at webnews@ For more stories like this, check our news page. MORE: Woman bombarded with hundreds of Amazon packages she never ordered MORE: Urgent recall of Ritz crackers over 'life-threatening' health risk MORE: Mystery after missing paddleboarder's body found in 'unusual' position on secluded lake
