Iowa Floodplain Mapping Project

Originally published on: January 19, 2012

The Iowa Floodplain Mapping Group next to the Iowa River

A group of students and faculty next to the Iowa River

Iowa Flood Center (IFC) researchers are about 1½ years into a four-year project that will provide floodplain maps for most of Iowa.

The Iowa Floodplain Mapping project is funded with $10 million from the U.S. Department of Housing and Urban Development. Working closely with the Iowa Department of Natural Resources (DNR), the IFC is preparing new floodplain maps for the 85 Iowa counties that were declared Presidential Disaster Areas following the 2008 floods.

“These maps will provide Iowans with new information concerning flood risk in their own communities, so they are empowered to make informed land use and land management decisions,” says IFC Associate Director Nathan Young, an IIHR associate research engineer and manager of the project.

IFC researchers are mapping all streams draining one square mile or more, relying on statewide LiDAR (laser radar) data recently collected by the Iowa DNR. LiDAR is a remote sensing technology used to develop digital elevation models of the land surface. This new data will make it possible to accurately describe Iowa’s river and stream networks, develop computer-based flood simulations, and delineate floodplains.

The actual mapping process follows very specific FEMA guidelines, and Young expects the new maps to be more accurate than older maps. “Besides the detailed LiDAR data, the IFC has more data related to regional and local precipitation and flooding frequencies than was available when many of the older floodplain maps were produced,” says Young.  “We are also using more refined techniques for developing the maps than those used for many older existing maps.”

The maps will be completed in a staggered schedule over the next 3–4 years. After IFC completes the mapping phase, the Iowa DNR will make the initial maps available for community review. Regulatory maps will be published once the maps have been reviewed and adopted by FEMA.

The final maps FEMA-approved maps will be available online to guide floodplain regulation and management.