New Study Finds Over 40 Million Americans at Risk From River Flooding

More than 40 million Americans are at risk from flooding rivers, according to a new study. This is over 3 times the current estimate based on FEMA flood maps.

The figures come from a groundbreaking study led by the University of Bristol in the United Kingdom, published on 28 February, 2018.

The timing of the study is apt. There are currently 5 states under a state of emergency (Louisiana, Kentucky, Indiana, Missouri and Michigan) as rivers across central and southern USA caused severe flooding.

Members from Coast Guard Station St. Joseph’s Ice-Rescue Team help evacuate individuals from their homes near St. Joseph River, Michigan, due to record flooding from heavy rain and melting ice, February 22, 2018. The flood waters were over two feet higher than anything previously experienced in the local area. (U.S. Coast Guard photo)

The new study has found that 41 million Americans are at risk from flooding rivers, which is more than three times the current estimate—based on regulatory flood maps—of 13 million people.

The study, published in the journal Environmental Research Letters, is based on a new high-resolution model that maps flood risk across the entire continental United States, whereas the existing regulatory flood maps produced by the Federal Emergency Management Agency (FEMA) cover about 60 percent of the continental U.S.

The increase in numbers of those at risk is a result of the expanded coverage of the map combined with its ability to estimate flooding on small streams—something that wasn’t adequately captured in previous flood-risk models, according to the study’s researchers.

Oliver Wing, the lead researcher behind the study and a PhD student at the University of Bristol’s School of Geographical Sciences, said that not only is the model is able to produce flood risk maps across the country, its level of accuracy on smaller scales—that is, along specific rivers—compares well with FEMA flood maps that presently serve as the primary source of flood hazard data in the U.S.

He added: “We were all surprised by how many Americans we found are exposed to flooding from rivers. It’s particularly worrisome considering that most of these people aren’t even aware of the risk they face. This research will help fill this critical information gap.”

Another key concern, Wing says, is that people continue to build in harm’s way, often without realising they are doing so.

The study—which integrates new maps from the Environmental Protection Agency that more precisely estimate where people live now and where future population growth is expected—predicts that under potential population growth and development projections, more than 60 million Americans may be vulnerable to a 100-year flood by 2050.

Wing added: “Because climate change may cause so-called ‘100-year’ floods to occur more frequently, even more people may be exposed to flooding in the future. All of this highlights the critical need for comprehensive floodplain and flood risk management planning.”

Kris Johnson, a scientist with The Nature Conservancy and co-author of the study, said: “By knowing those places most at risk from floods, we could avoid development in these areas.

“Protecting floodplains or developing them in ways that can withstand flooding—such as flood-tolerant parks—can prevent unnecessary risk to people and help avoid expensive damage to property and infrastructure. Floodplains also store and convey floodwaters, which can help prevent flooding in nearby communities.”

Johnson said avoiding future losses is particularly important as average flood losses in the U.S have increased steadily to nearly $10 billion annually. Consequently, the National Flood Insurance Program is now $24.6 billion into debt, not even counting the projected $16 billion cost of hurricanes Harvey and Irma last year.

He added: “Floodplains provide high quality habitats for wildlife, they can offer outstanding recreational opportunities for people, and they help improve water quality.

“Protecting and restoring the natural infrastructure of floodplains provides an important complement to built infrastructure like dams and levees. We need comprehensive approaches to reduce the devastating effects that flooding has on so many communities.”

The new study analyzes and identifies only those at risk from flooding from rivers. The estimate of 41 million people does not include the millions of additional Americans that are at risk of coastal flooding.

Source: University of Bristol

Flood Summary

Last updated: February 27, 2018
Event
Midwest and Southern USA, Southern Canada, February 2018
Date
February 16, 2018
Type
Flash flood, River flood
Cause
Extreme rainfall, Long-term rainfall, Snow melt

Locations

A - Pomeroy, OH (United States)
B - Jefferson, OH (United States)
C - Belmont, OH (United States)
D - Cincinnati (United States)
E - Point Pleasant, WV (United States)
F - Marseilles (United States)
G - Peotone (United States)
H - Fairplain (United States)
I - Croton Township (United States)
J - Lansing (United States)
K - Elkhart (United States)
L - Goshen (United States)
M - South Bend (United States)
N - Janesville (United States)
O - Rockwall (United States)
P - White Rock Creek (United States)
Q - Stilwell (United States)
R - Sodus Township (United States)
S - Orangeville (Canada)
T - Brantford (Canada)
U - Niles (United States)
V - Chatham-Kent (Canada)
W - Kalamazoo (United States)
X - Union County, Kentucky (United States)
Y - Simpson County, Kentucky (United States)
Z - Camden, Arkansas (United States)
- Watseka, IL, USA (United States)
- Grand Ecore, Louisiana (United States)

Magnitude

River level
15.85 metres
Ohio River at Cincinnati - February 18 to February 18, 2018
River level
15.36 metres
Ohio River at Pomeroy, Ohio - February 19 to February 19, 2018
River level
14.478 metres
Ohio River, Point Pleasant, WV, - February 19 to February 19, 2018
River level
5.25 metres
Thames river at Chatham-Kent, Ontario - February 25 to February 25, 2018
River level
12.46 metres
Ouachita River at Camden, Arkansas - February 26 to February 26, 2018
- 40.9 feet – 60.3 feet (moderate flood stage) – 9.7 feet – 26.8 feet – 50.49 feet
River level
18.38 metres
Ohio River, Cincinnati - February 26 to February 26, 2018
River level
2.95 metres
St Josephs River, South Bend, Indiana - February 26 to February 26, 2018
River level
8.17 metres
St Josephs River, Elkhart, Indiana - February 26 to February 26, 2018
River level
15.38 metres
Ohio River at Cannelton Lock and Dam, Kentucky / Indiana - February 26 to February 26, 2018
Rainfall level
60.7 mm in 24 hours
Meridian, Mississippi - February 25 to February 26, 2018
Rainfall level
63.5 mm in 24 hours
Jackson, Mississippi - February 25 to February 26, 2018
Rainfall level
61.2 mm in 24 hours
Cincinnati, Ohio - February 24 to February 25, 2018
Rainfall level
77.2 mm in 24 hours
Louisville, Kentucky - February 24 to February 25, 2018
Rainfall level
80.8 mm in 24 hours
Evansville, Indiana - February 24 to February 25, 2018
Rainfall level
57 mm in 24 hours
Lansing/Capital City, Michigan, USA - February 20 to February 21, 2018
Rainfall level
64 mm in 24 hours
Grand Rapids/Kent Co Michigan, USA - February 20 to February 21, 2018
Rainfall level
69.6 mm in 24 hours
South Bend/St.Joseph Co., Indiana, USA - February 20 to February 21, 2018
Rainfall level
54 mm in 24 hours
Chicago/O'Hare, Illinois, USA - February 20 to February 21, 2018
Rainfall level
64.6 mm in 24 hours
Lurgan Beach, Ontario, Canada - February 20 to February 21, 2018
Rainfall level
76.0 mm in 24 hours
Lucknow, Ontario, Canada - February 20 to February 21, 2018
Rainfall level
73.1 mm in 24 hours
Flesherton, Ontario, Canada - February 20 to February 21, 2018
River level
7.25 metres
Illinois River at Morris, Illinois, USA - February 21 to February 21, 2018
River level
3.50 metres
Muskegon River at Croton Dam, USA - February 21 to February 21, 2018
River level
4.28 metres
Grand River at Lansing, Indiana, USA - February 21 to February 21, 2018
River level
8.65 metres
St Joseph River at Elkhart, Indiana, USA - February 22 to February 22, 2018
River level
3.80 metres
Elkhart River at Goshen, Indiana, USA - February 21 to February 21, 2018
River level
5.14 metres
St. Joseph River, Niles, Indiana, USA - February 21 to February 21, 2018
River level
5.27 metres
Sugar River at Albany, Wisconsin - February 21 to February 21, 2018
River level
4.86 metres
Calcasieu River near Glenmora, Louisiana - February 27 to February 27, 2018
River level
10.45 metres
Red River at Grand Ecore, Louisiana - February 27 to February 27, 2018

Damages

Rescued
6 people
Ohio - February 16 to February 20, 2018
Fatalities
6 people
USA - February 19 to February 26, 2018
Missing people
1 person
Ontario, Canada - February 19 to February 23, 2018
Evacuated
400 people
USA - February 19 to February 23, 2018
Estimated figure - no official overall figures are available for the USA