Extreme precipitation events in the central U.S. increased as much as 40 percent between 1979 and 2009 compared to the previous 30 years (1948-1978).{{P.Y. Groisman, R.W. Knight, and T.R. Karl, “Changes in intense precipitation over the central United States,” Journal of Hydrometeorology 13, no. 1, 2012. 47-66.}} Yet many of the region’s infrastructure standards and floodplain maps are based on older precipitation data. Reducing the region’s exposure to flooding and optimizing long-term investments so that they account for future conditions requires a more current and comprehensive understanding of where and when urban and riverine flooding could occur. Watershed plans, stormwater models, and other studies help the region identify the most effective stormwater solutions, and coordination of these tools can help address problems across jurisdictional boundaries. In the absence of detailed models, the Regional Urban Flood Susceptibility Index can help convey the potential risk of urban flooding. Residents and business owners making important investment decisions often lack information about flood risk. Ironically, though established to provide affordable flood insurance, repair damaged homes and businesses, and promote floodplain management, the National Flood Insurance Program (NFIP) has the unintended effect of perpetuating development in flood-prone areas. This is particularly true in locations without strong floodplain management regulations that discourage redevelopment. The NFIP does not adequately communicate the level of risk, set premiums to reflect the full risk of loss, or provide options for low-income property owners.

Action 1

Regularly update precipitation data and explore options to account for future climate scenarios.


Illinois State Water Survey

Action 2

Update floodplain maps to reflect current development conditions as well as current and future precipitation.


FEMA, Illinois Department of Natural Resources (IDNR), and county stormwater agencies

Action 3

Continue advancing watershed and sewer modeling efforts to identify and increase awareness of areas of riverine and urban flooding risk.


County stormwater agencies and municipalities

Action 4

Collect flooding data and communicate risk and possible solutions to residents and businesses, with particular attention to residents who may be more vulnerable to the impacts of flooding.


Local governments

Action 5

Continue to develop planning tools to understand and plan for urban flooding risk.


CMAP and partners

Action 6

Implement efforts to ensure that the sale of property is informed by accurate flood risk information.


The State and real estate community

Action 7

Reform the NFIP to adequately identify and communicate risk.