Creek Flooding 101: What Happens During Severe Weather

News posted Jun. 01, 2017 - 6:00 am
Water Over Roadway

In April, Raleigh experienced heavy rain for nearly three days with total rainfall reaching about nine inches in some areas of the city, and averaging about seven inches across the city. A majority of that rainfall occurred during a 12-hour period. To put this in perspective, seven inches of rain applied over Raleigh’s 150-square-mile area equals approximately 17.7 billion gallons of water or 26,800 Olympic pools. In response to this rain event, many of the City’s creeks and streams experienced significant flooding.

Why Does This Happen?
When a large amount of rain falls in a short period of time, flooding within floodplains, like those beside Crabtree Creek and Walnut Creek, is likely to occur. This happens because the creek cannot handle the full volume of water flow within the stream bank causing it to naturally overflow. For this reason, flooding is expected in the floodplain during heavy rainfall events. Flash flooding also may occur during periods of highest-intensity rainfalls when the volume of water briefly overwhelms pipes and drains.

What You Should Do
Since not much can be done to stop the flooding during rain events that bring large amounts of rainfall to an area, the City urges residents to pay attention to road closures and barricades, which are put in place for driver and pedestrian safety. Most importantly, emergencies should be reported to 9-1-1.

How Stormwater Management Helps
The Stormwater Management Division limits new development within floodplains and acquires and restores floodplain areas in order to reduce damages related to flood events through the Federal Emergency Management Agency’s (FEMA) Hazard Mitigation Grant Program. This includes purchasing and demolishing properties and restoring the area to the natural function of the floodplain. To learn more, contact the Stormwater Management Division at 919-996-3940 or RaleighStormwater@raleighnc.gov.

This article was originally printed in the Stormwater Management Division's Urban Watersheds publication. Subscribe to learn more and to receive stormwater-related news.

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