The Iowa Flood Center (IFC) has released updated flood inundation maps for Rock Valley, Iowa following last summer’s flood event. In June 2024, major flooding in Northwest Iowa caused the Rock River in Rock Valley to rise to 27.7 feet, shattering the previous flood record of 22.7 feet set in June 2014. In response, the IFC updated its flood inundation maps to increase the maximum stage from 25 to 30 feet to more accurately represent potential flood scenarios.
The updated flood inundation maps are available to the public through the Iowa Flood Center’s publicly accessible Iowa Flood Information System (IFIS) online tool. Users can access the maps by visiting IFIS and clicking “inundation maps,” to select their community and view adjustable flood stage heights and flood extent and depth areas. These nonregulatory maps provide valuable information to help individuals and communities prepare for and respond to potential flooding.
New data has led to updates in how to understand flood risks in Rock Valley. Since the last maps were created in 2015, the IFC has collected more years of river flow data that can be used to estimate how often major floods occur. For example, what was considered a "100-year flood" in 2015 is now expected to happen more frequently. More advanced computer modeling techniques have also improved the accuracy of flood inundation maps, helping to better understand areas at risk and how communities can better prepare for flood hazards.
Detailed community-based maps are available for dozens of cities and small towns in Iowa (with more added every year) to show how predicted flood extent and depth could affect property and critical infrastructure. These inundation map libraries are meant to supplement National Weather Service river stage flood forecasts by providing a visual representation of potential inundation extent based on predicted river stage at stream gage locations. In addition, the IFC provides high-resolution interactive flood maps for every Iowa stream in all 99 counties showing the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year floodplain boundaries. The maps are also available through IFIS and provide critical information to evaluate flood risks and support decision-making, though they are considered non-regulatory. Maps that have completed review and become regulatory should be accessed through FEMA’s Flood Map Service Center.
The Iowa Flood Center is part of the University of Iowa College of Engineering and is the first and only center in the nation focused solely on flood-related research and education. The IFC was established by the state of Iowa in 2009 following the devastating 2008 floods to help Iowans understand and reduce their flood risks. For more information, visit iowafloodcenter.uiowa.edu.