How Raleigh manages flooding. A big test awaits.

Sourced from The News & Observer

Hurricane Florence could provide a difficult test for how Raleigh manages flooding.

As urban development increases in Raleigh, concrete and asphalt prevent rainwater from soaking into the ground and directs it towards streams and creeks instead. This rainwater also washes items such as soapy water, leaves and litter into drains and ditches, which lead to local streams and creeks. This increases the chance that local waterways will flood, and causes greater pollution and erosion in streams.

“We can only manage flooding, we can’t prevent it. What we try to do is understand where it can happen, and how often,” said Wayne Miles, stormwater program manager for the City of Raleigh.

Raleigh residents and commercial properties’ monthly stormwater fee — on average $5 per 2,260 feet of impervious surface — funds stormwater programs to decrease runoff and manage flooding, such as improvements to dams and underground pipes that manage stormwater. Raleigh has adopted several measures to manage flooding and stormwater. Here are a few of the most effective:

1. Computer modeling and analysis.
Raleigh’s Stormwater Management Division works with with the U.S. Geological Survey to place gauges along Raleigh waterways to monitor water levels. This includes places such as Pigeon House Branch Creek near Cameron Village, Crabtree Creek near Old Wake Forest Road, and Walnut Creek, off Fayetteville and Wilmington streets. The city also sends surveyors to measure water levels when flooding occurs. The data from these water gauges and surveys help the city develop computer models. “The computer models give us the freedom to simulate impacts and decide what improvements (we need to make),” Miles said.

2. Green stormwater infrastructure.
This form of landscaping makes a property more attractive and treats stormwater runoff. It incorporates vegetation that helps keep the air clean and holds soil together or uses rainwater to water plants. Planting inside medians along city streets is one way that Raleigh has promoted green infrastructure; Sandy Forks Road is one example. The city also included a green roof and rain garden at the new Union Station downtown.

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