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 we thought previously, according to a study published on Monday.

The study, published Monday in the Earth’s Future journal, revealed that 43% of the flooded buildings in North Carolina between 1996 and 2020 were located outside the flood risk zone of the Federal Emergency Management Agency – The areas that FEMA projects have a risk of 1% flood in a given year.

The results could help more communities better understand their flood risks and their flood insurance needs, study experts and authors said. Flood insurance has become more and more difficult to obtain as certain companies increase the price of the fonts or take a step back from houses in certain markets due to more frequent and more serious time. This left the owners more vulnerable.

Experts told NBC News only with access to good data sources, databases like that described in the study could be developed nationally.

FEMA maps are the main source on a national scale to identify areas subject to floods and what structures must be ensured. But experts say that the system is exceeded and has a low resolution. The projection of the 100 -year flood plain does not paint a complete table of the areas likely to flood. And climate change has made weather and climatic projections previously less reliable, noted the authors.

The use by the study of data at the address level allowed researchers to locate specific buildings that had flooded more than once. This information could help owners to know if they should buy flood insurance even outside the risk of FEMA flooding, experts said. In the United States, 99% of counties flooded at least once, but only 4% of owners have flood insurance, according to FEMA.

“More information on the place they have flooded in the past could help people make different decisions,” said Helena Margaret Garcia, principal of the study and doctoral student at the University of Caroline in North-Chapel Hill.

The FEMA and the National Flood Insurance Program have not returned requests for comments.

FEMA is currently in the process of redeveloping its flood mapping system, thanks to an initiative called the future of flood risks, which, according to him, will provide a more complete overview of risks and risks in the country using more efficient, precise and consistent technology.

While the planet warms up, stronger precipitation becomes more and more common because the warmer air can contain more humidity, which later falls in the form of rain. Climate change also leads to an increase in the world’s sea level, which has made coastal areas and even certain interior areas more vulnerable to floods. Hurricane Helene, the third most final hurricane in the modern era, caused serious floods in mountainous areas in the middle of North Carolina. Damage has totaled more than $ 78 billion, according to the National Oceanic and Atmospheric Administration.

Serious precipitation has caused sudden floods to tear in the United States in the past two weeks, more recently in New Jersey and New York on Monday. Extreme floods have led to at least six deaths in North Carolina and more than 100 deaths in Texas. Sudden floods are the best killer linked to the storm in the United States, resulting in an average of 125 deaths per year in recent decades, according to the National Weather Service

A climatologist of North Carolina said that the warmer ocean waters, which also feed the storms, could have been a factor in the food of the Tropical Storm Chantal last week, which beat the precipitation and crest of the river archives.

With the evolution of the climate, it is crucial to have access to up -to -date cards, according to experts.

For the study, researchers have mapped 78 flood events Between 1996 and 2020, the use of data from the national flood insurance program – the FEMA program by which owners can buy insurance for potential flood losses. They also used requests for emergency services and “volunteer geographic information”, which they have acquired via social networks publications, to create what they describe as a “first of its kind” database. Data on past floods are often difficult to access the general public, which can make it difficult for owners to know if their property has already flooded, experts said.

Garcia has said that researchers can use the same study methods to create similar historical cards for regions across the country to help managers identify the areas of their state that they might not have considered a risk of flood.

While the study revealed that only 20,000 of the 90,000 buildings have flooded more than once – more than double the number of buildings that have filed NFIP complaints – study authors are working on research to quantify its human impact. Some people examine health results, including how a flood could interrupt people’s health care, and others that examine the amount of movement due to repetitive floods, Garcia said.

Antonia Sebastian, assistant professor in the Department of Geological Sciences of UNC-Chapel Hill, said that the study was aimed at creating a “full recording of past floods” by collecting data on flooding events that do not make the biggest titles but always have an impact on the owners.

“The places that have already flooded it will flood it again. It’s just a matter of time,” said Sebastian. “And these are all risky places.”

Chad Berginnis, Executive Director of the Association of Flood Plain Managers who was not involved in the study, said that FEMA cards are designed to implement the NFIP by determining which areas to buy flood insurance, using the 100 -year flood plain as a guide. He said the analysis of the study on historical floods stresses that officials may need to require flood insurance in areas outside the FEMA flood risk zone.

“FEMA flood cards are a starting point and not an end point,” said Berginnis. “They will show you a type of flood risk, but if you want a total perception of the risk of flooding, one of the things you have to do is find information on historical floods.”

He said that the replication of similar database models than that described in the study in other local areas could help flood plain managers increase the awareness of their communities on which risk in identifying where it occurred.

“I have just received the history of the floods of [the Guadalupe River]And having a daughter of the age that also goes to the camps, I mean, it really strikes me. You know, how we, that we, socially, do not understand that these same locations can also be very risky areas and not require or know a little more about it. So, I clearly think that we do not have enough awareness of flood risks. »»

June Choi, a doctoral student in terrestrial system sciences at the University of Stanford who was not part of the study, said that the conclusion that many flooded buildings were located outside the risk areas designated by FEMA flood cards is probably the case in all states. The new database can be limited because it does not take into account the way in which construction density changes over time. But its use of historical recordings and specific data at the address always make it a precious resource to assess the risks of future flood, she said.