Flood risk for Iowa farmland

Date:
April 6, 2022
Source:
University of Iowa
Summary:
Researchers have created a detailed set of maps examining the
flood risk for all farmland in Iowa. The maps show 450,000 acres
of crops in areas with a 50% chance of flooding, and losses from
flooding averaging $230 million annually.



FULL STORY ==========================================================================
As farmers ready for planting season, a new study examines the flood
risk for all cropland in Iowa.


==========================================================================
The study from IIHR-Hydroscience and Engineering at the University of
Iowa is the first to detail the flood risk to farmland statewide. The researchers used flood maps developed at the Iowa Flood Center, and incorporated data from the Federal Emergency Management Agency (FEMA) and
the U.S. Department of Agriculture to create the crop flood-risk analysis.

Among the main findings:
* Nearly 450,000 acres of Iowa farmland are located in a two-year
flood
return period, meaning there's a 50% chance the land will flood
in a given year. That's less than 2% of the total farmable land
analyzed in the study.

* Iowa agriculture sees crop losses, on average, of $230 million a
year due
to farming that takes place in flood-prone areas.

The researchers also identified four watersheds as most vulnerable to
flooding and crop losses: Middle Cedar in east-central Iowa, North Raccoon
and South Skunk in central Iowa, and West Nishnabotna in southwest Iowa.

The new agricultural flood-risk maps developed by the IIHR researchers
can be updated to reflect changes in climate; changes in land use, such
as a shift in farming in a location; and changes to the landscape, such
as the addition of a road or other infrastructure, to give a continuous
picture of the flood potential for farmland across the state.

"It's a comprehensive approach to help create solutions with information
that helps farmers take a clear-eyed look at their land and for
policymakers and others to use as a starting point to determine how
Iowa's landscape can be best used to reduce flooding," says Enes Yildirim, graduate research assistant at IIHR and the study's corresponding author.



==========================================================================
The researchers analyzed nearly 25 million acres of agricultural land in
Iowa and farming operations from 2016 to 2020 to classify the flood risk according to eight scenarios: 2-year, 5-year, 10-year, 25-year, 50-year, 100-year, 200- year, and 500-year return periods. Cropland located in
a 2-year return period has a 50% chance of flooding in a given year;
farmland in a 5-year return period has a 20% of flooding in a given year;
while farmland in a 100-year return period has a 1% chance of flooding
in a given year.

The researchers then incorporated flood maps from FEMA and the U.S. Army
Corps of Engineers along with data from the USDA, including crop type,
yields, costs and price, planting frequency, and a corn suitability
rating, which indexes a farmland's productivity.

"We have taken all this information from federal agencies and
have tailored it to create a more dynamic picture about the current agricultural flood risk in Iowa," says Ibrahim Demir, associate professor
in civil and environmental engineering at Iowa and a study co-author.

Iowa has seen its fair share of flooding. Since 1953, 29 flood-related
disaster declarations have been issued for the state, according to
FEMA. Major, if not historic, flooding has occurred four times over the
past decade and a half alone -- in 2008, 2014, 2016, and 2019.

The new maps seek to address objectively the flood stress points,
by showing farmland that is prone to chronic flooding and has low
productivity yields compared to other areas.



==========================================================================
"We highlight the $230 million in average annualized losses to show that
there is farmland that is frequently exposed to floods and has a low
corn suitability rating -- why not consider changing its use?" Yildirim
says. "That, of course, would require further conversations, but you
have to look at the costs and benefits of continuing to farm that land." Policymakers also can entertain what to do with farmland that is prone
to regular flooding but is highly productive. That is especially true
for cropland in the West Nishnabotna region in southwest Iowa, the
researchers found.

"The West Nishnabotna is a region that has a high corn suitability
rating but also is exposed to regular flooding," Yildirim says. "So, it
might need extra protection from flooding to maintain food production,
such as building a levee, for example." The researchers found rotating
crops had a negligible impact on flood losses.

The study, "Agricultural flood vulnerability assessment and risk
quantification in Iowa," was published online Feb. 26 in the journal
Science of the Total Environment.

The University of Iowa and the Iowa Water Center funded the research.


========================================================================== Story Source: Materials provided by University_of_Iowa. Original written
by Richard C. Lewis.

Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* Maps_showing_flood_risk_in_Iowa ========================================================================== Journal Reference:
1. Enes Yildirim, Ibrahim Demir. Agricultural flood vulnerability
assessment
and risk quantification in Iowa. Science of The Total Environment,
2022; 826: 154165 DOI: 10.1016/j.scitotenv.2022.154165 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220406101626.htm

--- up 5 weeks, 2 days, 10 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)