Urban flooding is rising in frequency and cost, according to a new report from the Illinois Department of Natural Resources. The Illinois State Water Survey, part of the Prairie Research Institute at the University of Illinois, analyzed the scientific data for the report. Sally McConkey, the head of the Coordinated Hazard Assessment and Mapping Program at the ISWS, talked about the report’s findings and what communities and homeowners can do to reduce flood damage in an interview with News Bureau physical sciences editor Liz Ahlberg.
How much of a problem is urban flooding in Illinois?
Urban flooding is a problem across Illinois. It occurs in large cities and small towns alike. Between 2007 and 2014, there were nearly 150,000 flood damage insurance claims paid, and another 200,000 payments from the federal government to individuals affected by flooding in urban areas – and these numbers are just the reported damage. The number of people suffering flood damage is much higher.
What did the report reveal about urban flooding trends in Illinois?
The information points to an upswing in urban flooding in the last 15 years. We saw a lot of flooding in urban areas In 2008, 2010 and 2013, which is consistent with the observed increase in intense storms producing an inch or more of precipitation. Climate models indicate this upward trend will continue. The highest risk areas seem to be in the older areas of communities and buildings constructed in the 1950s and 1960s.
What factors contribute to flooding in urban areas of Illinois?
Urban flooding tends to be a unique combination of factors in any specific location; there isn’t one source or one answer. Many storm sewers were constructed decades ago, before stormwater management standards were in place and with limited information on rainfall. Those systems are aging and unable to handle more intense rainfall. As communities grow, there are more roofs and roads and parking lots where there used to be open areas that could soak up the rain. Runoff from the built environment means more is conveyed to storm sewers. And some places just tend to flood because they are low-lying or have soils that drain poorly.
What actions or infrastructures could mitigate or reduce urban flooding damages?
Communities can start by evaluating their storm sewer systems, preparing a plan for upgrading the system and possibly incorporating green infrastructure. New sewer systems will be costly. Residents need to understand that they have to pay to maintain the storm sewers just like any other utility: water, sanitary sewers, telephone, cable or Internet. Storm sewers are underground, so we tend to forget about them.
What can someone do in their home or neighborhood to decrease the chances of flood damage?
Keeping storm sewer inlets free of debris can really help with local road flooding.
Reporting problems to the community can help the community evaluate problems on a neighborhood scale.
Any property owner who has water problems should first take a look at the drainage patterns around their building. Depending on the source of the water, it might take a backflow valve or some regrading around the structure to remedy the problem. Check your homeowners insurance policy and see if you have sewer backup coverage. Flood insurance is not part of the typical homeowners policy, but it is offered through the National Flood Insurance Program. Check with your insurance agent to make sure you are adequately covered.