Flood risk for Iowa farmland —


As farmers prepared for planting season, a brand new examine examines the flood danger for all cropland in Iowa.

The examine from IIHR-Hydroscience and Engineering on the College of Iowa is the primary to element the flood danger to farmland statewide. The researchers used flood maps developed on the Iowa Flood Middle, and integrated knowledge from the Federal Emergency Administration Company (FEMA) and the U.S. Division of Agriculture to create the crop flood-risk evaluation.

Among the many fundamental findings:

  • Almost 450,000 acres of Iowa farmland are positioned in a two-year flood return interval, which means there is a 50% probability the land will flood in a given yr. That is lower than 2% of the whole farmable land analyzed within the examine.
  • Iowa agriculture sees crop losses, on common, of $230 million a yr attributable to farming that takes place in flood-prone areas.

The researchers additionally recognized 4 watersheds as most susceptible to flooding and crop losses: Center Cedar in east-central Iowa, North Raccoon and South Skunk in central Iowa, and West Nishnabotna in southwest Iowa.

The brand new agricultural flood-risk maps developed by the IIHR researchers could be up to date to replicate modifications in local weather; modifications in land use, reminiscent of a shift in farming in a location; and modifications to the panorama, such because the addition of a street or different infrastructure, to provide a steady image of the flood potential for farmland throughout the state.

“It is a complete method to assist create options with info that helps farmers take a clear-eyed take a look at their land and for policymakers and others to make use of as a place to begin to find out how Iowa’s panorama could be finest used to scale back flooding,” says Enes Yildirim, graduate analysis assistant at IIHR and the examine’s corresponding writer.

The researchers analyzed practically 25 million acres of agricultural land in Iowa and farming operations from 2016 to 2020 to categorise the flood danger in accordance with eight situations: 2-year, 5-year, 10-year, 25-year, 50-year, 100-year, 200-year, and 500-year return intervals. Cropland positioned in a 2-year return interval has a 50% probability of flooding in a given yr; farmland in a 5-year return interval has a 20% of flooding in a given yr; whereas farmland in a 100-year return interval has a 1% probability of flooding in a given yr.

The researchers then integrated flood maps from FEMA and the U.S. Military Corps of Engineers together with knowledge from the USDA, together with crop kind, yields, prices and worth, planting frequency, and a corn suitability score, which indexes a farmland’s productiveness.

“We now have taken all this info from federal businesses and have tailor-made it to create a extra dynamic image concerning the present agricultural flood danger in Iowa,” says Ibrahim Demir, affiliate professor in civil and environmental engineering at Iowa and a examine co-author.

Iowa has seen its fair proportion of flooding. Since 1953, 29 flood-related catastrophe declarations have been issued for the state, in accordance with FEMA. Main, if not historic, flooding has occurred 4 occasions over the previous decade and a half alone — in 2008, 2014, 2016, and 2019.

The brand new maps search to deal with objectively the flood stress factors, by exhibiting farmland that’s susceptible to power flooding and has low productiveness yields in comparison with different areas.

“We spotlight the $230 million in common annualized losses to point out that there’s farmland that’s regularly uncovered to floods and has a low corn suitability score — why not take into account altering its use?” Yildirim says. “That, after all, would require additional conversations, however you need to take a look at the prices and advantages of continuous to farm that land.”

Policymakers can also entertain what to do with farmland that’s susceptible to common flooding however is extremely productive. That’s very true for cropland within the West Nishnabotna area in southwest Iowa, the researchers discovered.

“The West Nishnabotna is a area that has a excessive corn suitability score but additionally is uncovered to common flooding,” Yildirim says. “So, it would want further safety from flooding to take care of meals manufacturing, reminiscent of constructing a levee, for instance.”

The researchers discovered rotating crops had a negligible affect on flood losses.

The examine, “Agricultural flood vulnerability evaluation and danger quantification in Iowa,” was revealed on-line Feb. 26 within the journal Science of the Complete Atmosphere.

The College of Iowa and the Iowa Water Middle funded the analysis.

Story Supply:

Supplies offered by College of Iowa. Unique written by Richard C. Lewis. Notice: Content material could also be edited for type and size.