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Iowa Floodplain Mapping Project

Accurate scientific information will be one of Iowa’s best defenses against future floods, according to IIHR Director Larry Weber.

Weber is part of an Iowa Flood Center (IFC) effort to update floodplain maps for 85 of Iowa’s 99 counties. The new floodplain maps will provide a direct and easy-to-understand way to communicate flood risk to Iowans.

The project is spearheaded by IFC Associate Director Nathan Young, who is also an associate research engineer at IIHR. IFC Director Witold Krajewski provides leadership for all IFC projects.

The IFC, located at the University of Iowa’s IIHR—Hydroscience & Engineering, is nearing the halfway point in the four-year Iowa Floodplain Mapping Project, 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 developing floodplain maps for the Iowa counties that were declared federal disaster areas after the 2008 floods. Some or all of the maps will eventually be adopted by the Federal Emergency Management Agency (FEMA) as regulatory maps.

Weber believes the maps will be an important new source of information for Iowans as they assess flood risk for their homes and communities. And with better information, people can make more informed choices about land use.

A Herculean Task

The scope of the project is huge. IFC researchers are mapping all streams draining one square mile or more. To accomplish this, they will rely heavily on statewide LiDAR (laser radar) data recently collected by the DNR.

LiDAR is a remote-sensing technology that researchers use to develop digital elevation models of the land surface. The availability of LiDAR was a major reason mapping funds were allocated to the state, Weber explains, since LiDAR data allow for more precise delineation of floodplain boundaries. With this data, the team will be able to describe Iowa’s river and stream networks, develop computer-based flood simulations, and delineate floodplains with reasonable accuracy.

The project involves digitizing the state’s stream network, performing hydraulic and hydrologic analyses, and using the results to create maps. After a successful pilot project in Poweshiek County, the team turned to the statewide project. The extent of the project requires the development of innovative, efficient new floodplain mapping tools, and the new data products will offer value beyond the mapping projects.

The project includes almost the entire state, and developing and managing such a large volume of data is a daunting task. Young leads a large team  of engineers, GIS staff, and students dedicated to the project. Partnering with the Iowa DNR has also been helpful,

Last modified on September 26th, 2012
Posted on May 10th, 2012