Rain-on-snow flood risk to increase in many mountain regions of the western US, Canada
By a
The greatest flood risk increases are projected for the
The findings were published in the journal Nature Climate Change.
Rain-on-snow events vary widely in timing and scale but can cause costly and damaging flooding as rapid snowmelt triggered by heavy and prolonged rainfall converge in a cascade that can overwhelm downstream rivers and reservoirs. In 2017,
"Rain-on-snow events can be intense and dangerous in mountainous areas, but they are still relatively poorly understood," said
To study the past, present and potential future of rain-on-snow events, the researchers turned to a state-of-the-art weather modeling dataset developed at NCAR. Known as CONUS 1, the dataset contains weather simulations across the continental
"This high-res dataset allows us to resolve mountains in granular fashion and examine the factors that combine to melt the snowpack when a warm storm comes in and hits cold mountains like the Sierra," Musselman said.
The authors found that in a warmer climate, less frequent snow-cover at lower elevations would decrease the risk for rain-on-snow flood events in areas like the
The rain and melt produced during rain-on-snow events is projected to increase for a majority of western North American river basins as rain rather than snow affects more mountain watersheds, increasing the corresponding flood risk by as much as 200 percent in localized areas and potentially straining existing flood control infrastructure.
"We were surprised at how big some of the projected changes were," Musselman said. "We didn't expect to see huge percentage increases in places that already have rain-on-snow flooding."
The findings represent an important first step toward better understanding rain-on-snow flood risk in the context of anthropogenic climate change, which could significantly shift the timing and extent of future flood regimes.
The researchers hope that continued investment in snowpack monitoring networks and efforts such as
Keywords for this news article include: Climate Change, Global Warming,
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