Iowa City Press-Citizen: UI to Reveal Flood Inundation Map

Thursday, September 1, 2011

By Josh O'Leary

Iowa City Press-Citizen

Residents near the Iowa River will no longer have to take the weatherman's word for it when it comes to predicting the effects of future floods.

A new Web-based flood inundation map for the Iowa City area, which is set to be unveiled today, will give users a new tool to see firsthand how varying river levels and flow rates will affect a flood's path.

The Iowa Flood Center, housed at the University of Iowa, has created an inundation map for Iowa City and five other cities -- Cedar Rapids, Charles City, Des Moines, Hills and Waterloo -- and a half-dozen more are in the works.

The map, which is available on the National Weather Service's website, gives users the ability to adjust the river's parameters and zoom in to see how their property might be affected at various flooding stages.

Carmen Langel, managing director of the Iowa Flood Center, said that, in the past, predictions were made based on the 100-year and 500-year flood maps. This new model, however, generates a detailed map for every 6 inches of water level.

"This kind of takes the guessing out," Langel said.

Iowa City Public Works director Rick Fosse said the map gives users the ability to do in seconds what previously had taken cities hours to calculate.

"The neat thing about it is that it's not only accessible to city staff, but it's also accessible for the public," Fosse said. "So if there's a particular flood forecast, they can get on this website and begin to make decisions about their own property -- what's their best option."

The state established the Iowa Flood Center at UI in the spring of 2009, a year after historic floods caused unprecedented damage in Eastern Iowa, including the Iowa City and Coralville area. In July 2010, the state gave the flood center about $10 million for its statewide floodplain mapping project.

With the Iowa City map now finalized, leaders of the project -- a collaboration between the Flood Center, cities and the National Weather Service -- will highlight the new model at a news conference today.

Had the mapping model been in place in 2008, Fosse said it would have been invaluable for residents faced with difficult decisions.

"It would have been a huge benefit to the people on the fringe of the flooded area who were trying to make decisions about what they should do," Fosse said. "In the end, some people did not take action that should have taken action, and other people took action who did not need to. This mapping will certainly help to reduce that."

The maps will not, however, eliminate much of the uncertainty inherent with flood forecasting, Fosse said.

"A flood may be predicted to go to a stage elevation of 23.5 feet, for instance, but where it ultimately ends up depends on what Mother Nature does to us between the time the forecast is made and when the flood peaks," he said.