China Posted November 17, 2021 Author Share Posted November 17, 2021 The Pacific Northwest Is in the Midst of a ‘Cascading Hazard’ Things are a deadly, dangerous mess in the Pacific Northwest right now. An atmospheric river dumped rain across the region over the weekend, prompting widespread flooding and mudslides. Much of the damage occurred in places still trying to recover from a devastating wildfire season this summer, showing how climate change can compound disasters. In British Columbia, around 275 people, including 50 children, had to be rescued off of flooded highways near Vancouver on Monday after they became trapped Sunday evening by a deluge of water, rocks, and mud. At one point on Tuesday, every major road out of Vancouver to the rest of Canada was closed. About 7,000 people in the town of Merritt, British Columbia, were ordered to evacuate Monday due to flooding and after the wastewater treatment system failed. This is the second time in less than six months that the town of Merritt was under an evacuation order. In August, residents were placed under an evacuation order as two wildfires raged nearby. The wildfire flames have long since been put out, but they’ve left an imprint on the land that’s making the flooding worse. Wildfires burn off an important layer of vegetation that, Brent Ward, a professor of earth sciences at Simon Fraser University and co-director of the Center for Natural Hazards Research, said “captures some of the rain and can slow it down before it gets into soil.” Wildfires can also change how the soil interacts with rainfall. “When the organic layer in the upper part of the soil burns, it creates these organic compounds that travel into the upper part of the mineral soil and kind of precipitate,” Ward said. “It’s this waxy substance, and it makes that impervious to water—we call that hydrophobic. The water, instead of kind of centering down into the soil, it can’t go anywhere. It runs off, and runs down the slope, and hits a sort of steeper slope, and it erodes a lot. The sediment that’s eroding is often enough to generate a debris flow.” Click on the link for the full article Link to comment Share on other sites More sharing options...
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