Severe Landslides In Washington Could Be Signs Of Times Ahead
A massive landslide that pushed 200,000 cubic yards of earth down the west side of Whidbey Island grabbed national headlines in March. Landslides have also caused numerous delays in passenger and freight rail along Puget Sound.
Ashley Ahearn from our EarthFix team reports the winter of 2012-2013 has been one of the worst on record for landslide destruction. And that has some wondering if the problem will get worse in the Northwest as a result of climate change.
One of the busiest stretches of railway in Washington State runs along the shores of Puget Sound, between Seattle and Everett. It’s also one of the most high-risk corridors for landslides.
Every day about 40 trains – full of freight or passengers – travel these tracks, en route from Seattle and points south, to Canada.
But for the moment, anyway, you won’t hear any approaching trains. Just some sea lions bantering offshore…
And some men in orange vests operating heavy machinery a little ways down the track.
Melonas: “We’re out here, as you can see, we have a ditcher front end-loader right now removing the debris.”
Gus Melonas is spokesman for BNSF Railway. Behind where he’s standing, a massive truck overflowing with exposed tree roots and mounds of earth rolls past, clearing the tracks after a recent landslide.
Melonas says this has been a bad year for slides.
Melonas: “This would rate right at the top – definitely top 5 as far as slide after slide – some feel top three.”
That’s top three worst years for landslides in BNSF’s recorded history. The company has been keeping a tally since 1914.
Landslides are caused by a lot of different things. Increases in housing development on bluffs, changes in vegetation.. but ultimately…
Godt: “What causes a landslide is ultimately gravity.”
That’s Jonathan Godt, He’s a scientist with the US Geological Survey and has studied landslides in Western Washington.
Godt: “You’ve got a steep slope and gravity wants to pull everything down and when water enters the soil it changes the stress of the soil.”
That’s right, water stresses out soil. It pushes the particles apart, weakening the composition of say, a bluff overlooking Puget Sound, and making the soil heavier with moisture.
Climate change experts predict that in the Northwest we could see more precipitation overall, with heavier downpours and storm events.
In Washington the average annual precipitation has increased by about 1/3 of an inch each decade since the beginning of the 20th century. And this winter saw above average rainfall in North Puget Sound.
That’s where BNSF says 95% of their landslide problems have occurred.
Whitely-Binder: “That has certainly arisen as a very prominent issue and one for which there is a very clear climate connection.”
That’s Lara Whitely-Binder. She’s with the Climate Impacts Group at the University of Washington. Whitely-Binder says that while you can loosely tie individual rain events to mudslides, there’s no way to prove that climate change is to blame for this year’s bout of landslides.
Landslides are nothing new for the Northwest. BNSF Railway has documented 900 slides on their tracks in the past 100 years.
But Whitely-Binder says in the future there could be more wet winters like this past one.
Whitely-Binder: “We would anticipate seeing a greater risk of landslides moving forward in time.”
The Washington State Department of Transportation had 55 rail cancelations due to mudslides in 2012.
Carol Lee Roalkvam heads environmental policy at WSDOT. In 2011 she co-authored an assessment of WSDOT’s vulnerability to climate change.
Roalkvam: “We’re aware now of more upriver flooding than we’ve seen in the past. More extreme rain events – the sudden and intense rain that we’ve been experiencing more frequently so a lot of the state routes are vulnerable to landslides today and the projections are that those will be worse.”
But Roalkvam says she’s confident that WSDOT has strategies in place to respond to the infrastructure risks posed by climate change.
Roalkvam: “I don’t think anyone can design themselves away from risk but I think we have a lot going for us here.”
Gus Melonas with BNSF agrees that there are a lot of near-term engineering solutions for the railway.
Melonas: “We’ve made appropriate drainage, ditching, we’ve put up catchment walls, retaining walls, slide detection fences, the marine wall along Puget Sound.”
Melonas added that the railroad has spent “millions and millions of dollars” on rail upkeep – but could not give a specific figure.
The federal government has provided 16 million dollars to fund landslide reinforcement at 6 sites along this problematic stretch of railroad.
Meanwhile, passenger rail traffic is on the rise and if a proposed coal export terminal is built near Bellingham, rail use could jump as much as 50% above existing traffic levels here.
Copyright 2013 Northwest Public Radio