The Severe Pacific Northwest Flooding Seen From Space

The State of Washington and the Province of BC are in a state of emergency following days of severe wind, rain, and flooding. The situation began when an “atmospheric river” (a plume of moisture) extended over the Pacific Northwest, triggering severe rainfall that caused already-rising rivers to overflow. This led to blocked roads, mudslides, fallen bridges, and thousands of animals drowning in farmland areas.

This extensive damage was photographed from space by Earth observation satellites, one of which was the European Space Agency’s (ESA) Copernicus Sentinel mission and the International Space Station (ISS). These images captured the extent of the floods in the Nooksack and Fraser River valleys this week, which both spilled over their banks this week, leading to washed-out roads and forcing the evacuation of thousands of people.

The Sentinel mission is a constellation of two identical Earth observations satellites designed by the EU to deliver a wealth of data and imagery central to the European Union’s Copernicus environmental program. Each satellite carries a wide array of high-resolution multispectral imagers that can photograph the Earth’s land and vegetation in 13 different spectral bands.

The image above (above left) was taken by Sentinel-2 in the optical band and shows the flooded areas between the towns of Linden and Ferndale (indicated in brown) and all the heavy sediment emptying into Lumni and Bellingham Bay (lower left side of the image). The Sentinel-2 images could not penetrate the clouds, but Sentinel-1 snapped additional photos in the radar band (above right) on Nov. 4th and 16th (before and after the heavy rains).

These images were combined to create the composite above and indicate the flooded areas in blue, with the darkest areas corresponding to the heaviest inundation. In addition to the hundreds who were evacuated, more than 158,000 people were affected state-wide by the resulting power outages and disruptions to other services. The torrential rainfall also led to mudslides that forced the closure of Interstate 5, which was since re-opened.

In similar news, former ISS Commander Col. Chris Hadfield shared a NASA image via Twitter that shows the extent of flooding from the Fraser River in interior British Columbia. As he noted in the tweet, the flooding up-river resulted in a tremendous amount of topsoil being washed out into the Salish Sea between the mainland and Vancouver Island, though out instances of outflow can be seen along the coast of Vancouver Island and Washington State.

For instance, one can see the sediment pouring out into the Saanich Inlet, the large bay in the lower left-hand side of the image that sits between the Saanich Peninsula and the southern tip of Vancouver Island. Further north, there are also outflows around the Gulf Islands and between the city of Nanaimo and Gabriola Island (center left). The image also manages to capture the flooding imaged by the Sentinel satellites, particularly in Bellingham Bay (center-lower right) and further south in Puget Sound (lower right).

These images illustrate the extent of this recent bout of extreme weather, described as the worst case of flooding in over a century. They also show how Earth Observation satellites are essential to recognizing and addressing the symptoms of Climate Change. As average temperatures, sea levels, flooding, and extreme weather increase due to higher levels of CO² in the atmosphere, satellite images help to understand and respond to resulting disasters.

They also help us to appreciate the extent of the problem and see it in a way that reminds us that Earth is a single system, and what happens in one part of the world has direct consequences for all the other parts.

Further Reading: ESA, CTV News Vancouver