Flash flooding could become the norm

Posted in: Water


nfip-300x200pxThe National Flood Insurance Program is up for Congressional re-authorization in September 2017. The program may expire unless a bill to continue the program is passed through both the House and Senate. The upcoming reauthorization process is an opportunity to review the program. The time is here to make changes to safeguard people and property, limit taxpayer liability and ensure that the NFIP continues to help people.

Rising sea levels and flash flooding could become the norm. Continuing to design publicly funded infrastructure will result in having to repair and rebuild infrastructure over and over again as more intense storms occur. It is important to account for future conditions, like a greater chance of occurrence of heavy rain events. Communities should plan defenses based on the future, not the past. This is a challenge for many communities to recognize as most infrastructure was designed to reflect the past.

According to the National Weather Service, the Louisiana flooding early this August was considered a 1-in-500 year rainfall event. There have been nine 1-in-1,000 year rainfall events in the U.S. since 2010. In just the past 17 months, eight rain events occurred that were considered to exceed the 500-year recurrence interval. Three of these events happened in the past three months.

As designers our criteria are often based on historical records. What will the extreme precipitation events of the future mean for us? We need to understand what will the 100- and 500-year floods look like 50 years from now and not just today.

Future risk needs to be taken into account. More frequent flood events could change the traditional methods for flood planning, like using the 100-and 500-year floodplain maps to plan how an area will be developed. Mitigation strategies ahead of a disaster can help a community become better prepared and reduce future impacts.

Communities can influence any future changes to the National Flood Insurance Program. It’s more cost effective to take action to protect assets now rather than wait for a flood to strike.


Karen Wiemeri

About the Author

Karen Wiemeri, P.E., is a project manager in the Water Group. She provides design and technical support for structural flood mitigation measures. Through her work with structural flood mitigation and stormwater management, Karen has an increased interest in more sustainable approaches to flood risk management that can complement existing defenses.

Read more posts by Karen Wiemeri

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