My research assistant never really understood that water could be a nuisance, let alone a danger.
As we walk the scenic river promenade along the Skagit River, we don’t really notice how this town is adapting to climate change. We don’t feel a threat from the lovely water scene in front of us, nor the position of this attractive walk, on top of a raised riverbank, looking down on both the river and the town streets along it. Until we think about it, it’s not obvious that if the river were to overtop the bank - even by a few inches - it would pour down into the business district.
And there’s almost nothing to show us that the town is very worried about this catastrophic flooding. The unobtrusive protections the town’s engineering department has installed are hard to notice. Most days of the year, dark slots in the brick wall like this is all there is to see.
But when the river is about to flood the town, this is how that slot is used,
Panels are fitted into the slots, creating a temporary floodwall. More than once, the wall has successfully kept the river from inundating Mt. Vernon, this historic town in Washington State near my home.
A rising need
River floods are caused by more frequent and heavier rainfall, and that’s happening across the Midwest, Pacific Northwest, and northern Great Plains. In those areas, warmer temperatures increase evaporation, putting extra moisture into the air which then gets released as rain or snowfall. As extreme precipitation increases, so does flash flooding.
Across the state of Washington, the costs of flooding exceed all other natural disasters. In any given year, there is a better than an 80% chance that 10 or more floods will occur. We are responding to and preparing for more floods as climate change intensifies the risk. [WA Dept. of Ecology]
It’s important to understand that the problem doesn’t affect the whole country. The height of inland floods has actually decreased in the West, southern Appalachia, the Southwest, the Rockies and northern Michigan.
But then there are the coastal states. The increase of severe ocean storms, along with sea level rise, means that many coastal communities are facing more and more saltwater flooding. Some communities, both riverside and oceanside, will be rendered uninhabitable over the decades ahead. But for the time being many of these hazards are a matter of just a few dangerous inches a few times a year.
What do we look for?
There are hundreds of temporary flood barriers installed around the country. They range from protecting a single doorway to walling off a building like the Art Center at the University of Iowa, to the barrier a third of a mile long protecting more than twenty downtown blocks in Mt. Vernon.
It’s not always easy to spot them until, as a flood approaches, they get set up. Mt. Vernon’s $30 million project has been in place since 2018, but because the floodwall panels and most of the posts that support it are stored inconspicuously until needed, it’s virtually invisible.
Almost all the components of the city’s flood wall are sorted, color coded for fit, stacked in storage containers, and placed inconspicuously near the river. With the town’s existing equipment, their contents can be quickly moved to exactly where they’re needed. (Photo courtesy Blaine Chesterfield, Engineering Manager, Mt. Vernon)
Flood barriers are just one more way we are adapting to the effects of climate change, along with sandbags, permeable pavement, electric school buses, and drought-resistant landscaping. I’ll be looking at a half-dozen more such adaptation tactics in the coming weeks.
LEARN, THINK, ACT
Here’s a good place to see the components and construction of floodwalls and some of the many installations across the country.
On this map, we can see where the magnitude and frequency of river flooding has been increasing and decreasing.
FEMA’s Flood Mitigation Assistance program provides grants for building flood walls.