The Tide is High, But I’m Holding On: Stormwater Challenges in Coastal Regions and the Path Toward Resilience

Coastal stormwater managers are facing unprecedented challenges when it comes to tackling stormwater flows. Many factors come together to create an especially tough situation along our coastlines. Today, we’ll share four images that highlight the multiple issues “flowing” together to make coastal stormwater management such a challenge, and then we’ll discuss the first steps we need to take down the path toward resilience.

(1) Home is…where the COAST is!

The population density in coastal communities is over SIX TIMES greater than that of corresponding inland communities. Along with surfboards (😉) all those people bring with them…pavement (!) and other impervious surfaces that make it impossible for the land in these areas to absorb rainfall naturally. Thus, coastal regions are at risk for increased flooding and water pollution due to stormwater. Remember, this is before we even take climate change into consideration!

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(2) The tides are moving in…and they’re here to stay!

Historically, stormwater systems were designed to funnel rain waters out to sea (or river…) to reduce flooding. Well, now we’ve come full circle, because these systems are starting to funnel seawater inland. In many coastal regions, tidal Intrusion into coastal infrastructure systems is the new normal. For example, those working in Charleston, SC, have observed that storms occurring within 2 hours of high tide take significantly longer to drain, which can lead to localized flooding. This effect gets even worse during king tide events.

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(3) The main ingredient in stormwater is…..storms!

Rain frequency and intensity is expected to change throughout the country as climate change progresses. The threat is increased along those of our coastlines that lie in the path of severe storms and hurricanes. Data show that, while the frequency of hurricanes remains relatively consistent, the intensity of these storms is increasing. Warmer air and water temperatures combine with higher sea levels to increase all of the ingredients needed to create intense storms.

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(4) Bringing it all together

We’ve seen that increased population, sea level, and storm intensity all come together to amplify the stormwater-related risks that need to be managed along our coasts. So what’s the bottom line?

A new study from Princeton University has pulled these factors together and concluded that what’s currently considered a 100-year flood events (which, statistically, only have a 1% chance of occurring each year) will now occur every 1 to 30 years along our coasts.

This study utilized the latest climate data on sea level rise and tropical cyclone activity to determine the relative contribution of each of these factors. The found that in Northern regions, sea level rise is more influential, while changing storm intensity is more of a factor along our southern coasts.

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Moving Toward {Stormwater} Resilience

What can managers in coastal regions do NOW to alleviate these threats?  First: get to know your counterparts in other departments! As climate change progresses, professionals who have rarely found cause to work together suddenly find themselves in the same space (often, the coastline… 😉). Stormwater professionals, have you hugged an oceanographer lately? Or perhaps a meteorologist or architect?  We all hold valuable pieces of the puzzle and it’s important to learn to work together.

Second: define your problem in a regionally specific way:

Problems of ANY type are impossible to address effectively if they are not well defined. Flooding in urban areas is especially hard to address because it often exists outside of the traditionally mapped zones. “It isn’t dictated by natural landscapes but is instead reliant on an unmapped series of impermeable roads and parking lots. Its outlets aren’t river mouths, but storm drains of varying capacity.” Now imagine those storm drains are already full of seawater when a *stronger than normal* storm hits.  What are the impacts to your area? Not just above ground, but within the stormwater system itself. Have you defined these impacts on your system now, so you can plan for changes in the future?

StormSensor can help!

We have designed an affordable system that allows you to track precipitation and flows into and out of your stormwater system; think of it as Google traffic maps, but for water! All of our data are available to you in real-time via our cloud-based software. And in the off chance you’re not glued to your screen 24/7, we’ve got you covered. We use AI to continually monitor your data and have even defined several real-time alerts to direct your attention to potential issues as they pop up. Tracking flows in this way can help you to determine hotspots for flooding, tidal intrusion, or system failure so you can plan upgrades in an informed manner and continue to track their success!

Interested in learning how the StormSensor system could benefit your region? Schedule a short demo with us!

About the author

Suzie Housely

Talk stormwater with Suzie has over a decade of experience in the Stormwater industry including both government and academic work. She leans on her experience to meaningfully interpret scientific studies and government policies to communicate a practical message. Suzie lives just outside Nashville, TN and gets outside whenever she can to explore nature with her husband and two small children.