Flood inundation maps help with planning, decisions

IOWA CITY - Residents, business owners and city leaders around Iowa likely will have a new tool during future floods - inundation maps that show flood risk well beyond the reaches of a community's 100-year floodplain and can be called up with the click of a mouse.

The Iowa City-area flood inundation map was posted this week to the National Weather Service website, the first such NWS inundation map for an Iowa community, officials said in unveiling the tool Thursday at the University of Iowa. The UI's Iowa Flood Center joined with the National Weather Service and the city of Iowa City to make the inundation map more accessible and user friendly by putting it on the NWS site.

To view the map, click here.

Cedar Rapids, Waterloo and Elkader are the primary candidates to be the next Iowa communities to have flood inundation maps posted to the National Weather Service site, officials said.

The new maps are important because they visually show the inundation levels for a variety of flood stages, Rick Fosse, Iowa City public works director, said. The maps show the extent of the flooded landscape with every six-inch rise in the flood level. Previously, anything other than a 100-year flood event or a 500-year flood event - where maps were already drawn up - required city officials to spend hours mapping the possible inundation levels in between, Fosse said.

"What this tool does is it makes that information available in a second," he said.

Such a map would have been a wonderful tool during the flood of 2008, to help people know if they did or did not need to prepare and evacuate, Fosse said.

"Especially for people around the perimeter of flooding," he said. "People can get an idea of their flood risk even if they're beyond the 100-year floodplain."

Similar inundation maps are already available on the Iowa Flood Center website for numerous Iowa communities, including Iowa City, but putting the information on the National Weather Service site makes it a more user-friendly format and includes additional data and information, officials said.

The Iowa Flood Center has been developing such inundation maps, including these Iowa River maps, for Iowa communities since the center was launched two years ago.

"It puts the information in context for better planning," Nathan Young, associate director of the Iowa Flood Center, said.

Improving flood preparedness is one of the center's key goals, Young said. The inundation maps will be maintained and updated as necessary, Young said, such as when flood mitigation measures in the future change flooding models.

National Weather Service officials hope to get inundation maps for more Iowa communities added to the organization's website, Maren Stoflet, service hydrologist with the National Weather Service in the Quad Cities, said.

"We hope to expand these maps ... to make these much more widespread," she said.