A nonprofit consortium of university researchers have reassessed the flood risk for every property in the nation -- more than 142 million homes and properties across the contiguous U.S. -- exposing a federal flood mapping system that is often either badly outdated or missing information altogether.
Brooklyn-based First Street Foundation's release Monday of its flood risk data -- and its modernized, more comprehensive model for assessing it -- identifies 70% more properties nationwide with flood risk than the Federal Emergency Management Agency's Special Flood Hazard Areas maps.
In Michigan, First Street finds almost 400,000 more properties with flood risk than FEMA identifies -- a big potential liability for property owners and renters, as most outside of FEMA flood zones are probably not covered by flood insurance, meaning their regular insurance wouldn't cover their losses if a flood occurred, and forcing residents to pay out of pocket for hundreds or even thousands of dollars in damages. .
Detroit -- not surprisingly, given it's the largest city in Michigan -- has the most properties identified as being at some flood risk under First Street's evaluation, with 39,744 parcels. Next on the list is Warren, with 11,916 parcels identified with some flood risk, followed by Grand Rapids with 9,448 parcels.
How many properties are affected in my community?
Explore the map and zoom in to see how the number of properties at risk of flooding in your area.
"We did this because the data hasn't existed," said Matthew Eby, founder and executive director of First Street.
Understanding flood risk in the U.S. has customarily meant looking at FEMA maps, designed to delineate flood risk areas for purposes of requiring those within them seeking a federally-backed mortgage to obtain flood insurance. But those maps come with limitations, Eby said.
"They look historically to understand your current risk," he said. "They say, 'Based on all of these events that have happened in the past, what is the likelihood of that happening again, today?' on an annualized basis.
"What we've done that's different from that is, we say, let's take all of those past events and learn from them, but also, what was the environment like when all of those events happened, and what does the current environment look like? The current atmospheric temperature, the current sea surface temperature. How does that change current risk?"
First Street, unlike FEMA, also looks at changing flood risk into the future, factoring in climate change.
How does flooding risk compare to neighboring communities?
Filter the table to see the number of properties in a flood zone, defined as a 1% annual likelihood of flooding in 2020.
"The flood risk isn't static; it's changing all the time," Eby said. "The atmosphere is getting warmer; sea surface temperatures are getting warmer. And those all fundamentally change the risk of flooding."
First Street also looks at rainfall-related flooding in different ways than FEMA does, and looks further away from rivers and lakes into smaller streams and tributaries and the potential for flooding around them.
Among the First Street flood risk study's findings for Michigan:
FEMA counts just over 124,000 properties across Michigan as in Special Flood Hazard Areas, meaning they have a 1% or greater chance of flooding every year. First Street's method finds 516,760 parcels at that level of flood risk, more than four times as many. Some 60,500 properties statewide have a Flood Factor score of 9 or 10, indicating a "severe" or "extreme" risk of flooding. Of those, 51,710 properties are considered to have a greater than 99% chance of flooding of a centimeter or more at the home or building footprint within the next 30 years. Flood risk exists whether a community is rich or poor. The city with the highest percentage of its total parcels at flood risk is River Rouge, at 81%. Coming in second is Grosse Pointe Woods with 60% of its total parcels at risk. River Rouge has a median household income of $29,671; Grosse Pointe Woods' is $95,697. In Emmet County, at the Tip of the Mitt on the Lake Michigan side, FEMA maps identify 199 parcels at flood risk. First Street's method finds 2,136 parcels at flood risk, more than 10 times as many. It's a similar story in Gladwin County, where FEMA lists 495 parcels at flood risk, about 2% of total parcels. First Street lists 5,235 parcels at flood risk, about 19% of total parcels in the county.
The large-scale flooding in Midland County last month caused by two failed dams wouldn't be captured in First Street's analysis, which presumes that dams and levees are in good working order.
First Street director of research and development Jeremy Porter was surprised by what he didn't find in Michigan's data.
"Outside of downtown Detroit, there's really not any FEMA special flood hazard areas," he said. "From Warren, all the way over to Southfield, south of Dearborn is almost completely empty of FEMA special flood hazard areas.
Kelly Karll is the environment and infrastructure manager at the Southeast Michigan Council of Governments, a regional planning agency. She's quite familiar with the limitations of FEMA data on flood risk, and said she's "excited to look at" First Street's new study.
"In areas where communities aren't part of the FEMA flood insurance program, those areas aren't mapped. But there's still flooding that occurs there," she said. "In areas where it has been studied, the data's very old."
Even areas where FEMA has updated flood studies within the past 10 years, it appears to have been built off a foundation of old, paper flood maps, Karll said.
"A lot of the data is still based on the 1970s," she said.
"We all know over the last 30-40 years we have more frequent rainfall, more intense rain storms, more rain each year. Combine that with all of the development that's occurred -- more impervious surfaces relates to more runoff."
FEMA itself understands its flood assessment limitations. In Feb. 27 testimony before a House subcommittee, Michael Grimm, assistant administrator for risk management for FEMA's Federal Insurance and Mitigation Administration, testified about the federal flood mapping program.
"While maintaining current flood maps is critical, we are still far from completing the initial job of mapping the entire nation," he said. "There are many counties and communities throughout the nation identified as not having flood maps at all."
FEMA has historically prioritized limited mapping resources to the most highly populated areas. "The unfortunate consequence is that areas of potential future development remain unmapped," Grimm said.
"Furthermore, there are roughly 3,300 communities with maps that are over 15 years old."
Grimm added that new flood maps were taking seven years to complete on average due to various regulations with which FEMA must comply. Yet FEMA's regulations call for it to reassess flood maps every five years to qualify them as current, he said.
"(It) can result in a situation in which maps have technically expired by the time that they are approved and publicly available," he said.
Grimm also testified about FEMA's "lack of consideration about future weather patterns and changing coastal conditions" in the development of its flood maps, "important factors" for communities on the ocean coasts and "communities along the Great Lakes."
In Detroit neighborhood, flood risk high, mostly unknown
Amanda Johnson moved into her home on Warwick Street, in west Detroit east of Rouge Park, two-and-a-half years ago. Then the rains and the flooding, came.
"Twelve days after we moved in," she said, sitting on a bicycle outside her home, her 2-year-old daughter, Willow Brown, strapped in the back. "They didn't recover anything; I just had to throw everything away."
She's endured three flood events at the house.
"I have low-income housing," she said. "You contact people, and they told me, '(You need) flood insurance.' And it just keeps flooding. Anytime it rains, there are foundation issues over here.
"There's really nothing you can do. It's an older home, and I don't have the money to fix it."
So Johnson and her daughter are now planning to move to Dearborn Heights next month.
FEMA considers Johnson's neighborhood an "area of minimal flood hazard." But First Street Foundation's assessment puts it at a "severe" or "extreme" risk of flooding within the next 30 years, at a 9 or 10 on its "Flood Factor" scale of 10.
Down Warwick Street from Johnson, Shirley Ellis has lived in her home since 1990. She was surprised to learn it's listed at extreme flood risk.
"I'm not planning on getting (flood insurance); I'll move first," she said. "I can't afford it."
It was a recurring theme cited by residents in and near the Warrendale neighborhood: renters whose insurance coverage, if any, almost certainly doesn't cover flood damages; no flood insurance and no financial means to buy any.
"In the vast majority of cases, it's, 'I'm not in a flood zone. Great; I don't need flood insurance,'" Eby said. "And what happens is, like Hurricanes Irma and Harvey, three-quarters of the flood damage is for uninsured residential homeowners who now have no mechanism to try to build back their home because they don't have any insurance to give them the financial means to do so."
How FEMA‘s maps compare
Explore the map and zoom in to see how FEMA‘s map compares to First Street‘s.
Other avenues for study
First Street will be able to add inputs to its supercomputers and update its Flood Factor analysis nationwide on a continuing basis, Eby said. Already, about 100 academic researchers at 20 different universities are using First Street's data sets for diverse research, Porter said.
"It's primarily economists and sociologists interested in the social and economic impacts of flood risk," he said.
As First Street makes much of its data publicly available, it can also sell its valuable data sets to for-profit companies -- helping fund the building of further, similar modeling, Eby said.
"We can do the same thing around heat and drought and fire," he said. "So then you can end up with a Fire Factor, or a Heat Factor, a Drought Factor, to truly understand all of these perils and risks and how they impact the individual property."
Contact Keith Matheny: 313-222-5021 or [email protected].
This article originally appeared on Detroit Free Press: What's your home's flood risk? New study measures it for every parcel nationwide
(c)2020 the Detroit Free Press
Visit the Detroit Free Press at www.freep.com
Distributed by Tribune Content Agency, LLC.