IFC Completes Statewide Floodplain Maps

November 29, 2016

Floodplain map of Audubon, Iowa featuring the river

Floodplain map for Audubon, Iowa.

Easy-to-access, science-based information is one of the best tools we have to protect ourselves from flooding. The Iowa Flood Center (IFC) recently celebrated the completion of a six-year project to develop updated floodplain maps for the 85 Iowa counties that were declared Presidential Disaster Areas after the 2008 Iowa floods. The U.S. Corps of Engineers mapped the remaining 14 Iowa counties.

Nate Young interviewed by TV crew

IFC Associate Director Nathan Young (left) speaks with the media about the completion of the floodplain mapping project.

The IFC researchers used laser radar (LiDAR) data provided by the IDNR to map all streams draining one square mile or more. This LiDAR remote-sensing technology allowed researchers to precisely map Iowa’s river and stream network, develop computer-based flood simulations, and delineate floodplains with reasonable accuracy.The IFC hosted a seminar and reception in Iowa City on Nov. 28 to celebrate what IFC co-founder Larry Weber called “one of the crowning achievements of the Iowa Flood Center.” IFC Associate Director Nate Young, who served as leader of the project, presented a seminar highlighting the partnerships, processes, and perseverance that had brought the project to its successful conclusion. The Iowa Statewide Floodplain Mapping project was a collaboration among the Iowa Flood Center, the Iowa Department of Natural Resources (IDNR), the Iowa Natural Heritage Foundation, the U.S. Army Corps of Engineers, and the Federal Emergency Management Agency (FEMA).

A topographic map, with high points around a river

Statewide LiDAR (laser radar) data provided by the Iowa DNR provided detailed topographic data for the floodplain mapping effort.

The new floodplain maps provide Iowans with sound information on flood risk in their communities, so they can make informed land-use and land-management decisions. The maps define the boundaries of flooded areas for 100-year (1 percent annual chance of flood) and 500-year (0.2 percent chance) floods. Funding from the Iowa Natural Heritage Foundation allowed the team to also create maps for 2-, 5-, 10-, 25-, 50-, and 200-year floods.

The easy-to-use Google Maps–based web interface allows Iowans to directly access the maps. The IFC developed the entire library of flood maps to meet the standards of the Federal Emergency Management Agency (FEMA). FEMA will adopt some of the maps as regulatory documents. The remaining maps are available on the website to provide accurate information to Iowans, but are not FEMA regulatory maps.