AK - How Alaska's coastal communities are racing against erosion
A sandy bluff towers above the beach in Dillingham, Alaska. Every year, Alaska Native resident Ken Shade watches as a little more of his land falls over the edge, into the sea.
Dillingham is just one example of a small Alaskan town with a big erosion problem. Around the state, dozens of coastal communities are watching their coastlines crumble, losing at least 3 feet of land per year. Critical infrastructure such as airport runways, fuel tanks, and schools are in danger. Many Alaska Natives have been hard hit: Now, with climate change altering weather patterns, melting permafrost, and reducing sea ice, the land these communities are built on is falling into the sea.
Shade has already moved his house farther away from the bluff once, about 25 years ago, to save it from falling over the edge. The process took him a whole summer. After digging around the foundation and jacking up the house, he slid the building onto a trailer built out of old car axles, then dragged the whole thing using heavy machinery. His neighbor, a mechanic, took a different approach and tried to stabilize the bluff by building a wall in front of it using dozens of old cars. “It doesn’t work too well,” Shade said. Now when he sets out fishing nets, he catches car parts along with the salmon.
Other parts of town are also losing ground fast. The earth in front of Dillingham’s sewage lagoon — two open-air cells that hold the city’s wastewater — is receding at a rate of about 16 feet per year. Meanwhile, a mass grave containing victims of tuberculosis and the 1918 flu pandemic is slowly falling out of the bluff and onto the beach below.
“There’s just multiple issues everywhere,” said Dillingham city planner Patty Buholm.
Some communities have moved because of erosion. But the process can cost upwards of $100 million and involves giving up traditional land. Ways of stabilizing the ground, and letting communities stay in place, are sorely needed.
[Read next: As permafrost thaws, the ground beneath Alaska is collapsing]
The classic strategy is to build a large, rigid structure, such as a seawall or a revetment (i.e., a pile of boulders) between the water and the eroding land. Such structures have stabilized many Alaskan coastlines by shielding them from waves, but they’re fantastically expensive (think millions of dollars) and it can be difficult to transport the construction materials to remote locations.
What’s more, these techniques were developed in temperate regions. Some engineers think they’re likely to fail Alaska in the long term because they ignore a problem unique to cold regions: As permafrost melts, the land is turning to mush. Seawalls that were once along the coast may end up in the middle of the ocean as the land adjacent to them sinks and retreats.
