Colorado Springs, Colorado 2021-07-23 18:28:33 –
Areas burnt during last year’s historic wildfire season can pose a flash flood risk throughout the summer as rain speeds up along the steep terrain of burn scars and clears debris on major roads.
Heavy rains are typical of the summer monsoon season, but Colorado has an “abnormal flood year”, partly due to last year’s historic wildfire season and increased area of scorched land, state climate. Said assistant scholar Becky Bollinger.
So far this year, landslides along the burn scars have caused dozens of road closures, including along Glenwood Canyon’s Interstate 70, resulting in serious traffic delays or serious detours. The change in soil composition along the burn scars is likely to continue until the end of the monsoon season, Bollinger said.
Bollinger compared the rainfall along the burn scars to the rain that hits the car and quickly escapes, instead of the rain seeping into the soil.
“What’s happening in the soil, especially in areas hit by wildfires last year, is that it almost repels that water,” she said. “Basically, a fire changes the composition of the soil, preventing water from entering the soil as it normally would.”
In steep terrain, rain slides run down the slopes, making floods more dangerous as speeds increase, Bollinger said. If the slope is next to the road, it is exponentially dangerous.
“That slope creates flash floods, as opposed to normal flood events,” she said.
Rain can erode 24-40 tonnes of steep terrain per acre each year The first few years after the wildfire, according to the US Forest Office.
Vehicle and recreational traffic through Glenwood Canyon was blocked several times last month due to the high risk of flash floods after mud was washed off the road from the grizzly leak burn scars. On Thursday night, the lanes in both directions were closed again and there was no scheduled time to reopen. More rain wipes out large debris, then piles of debris along the road, The Colorado Department of Transportation said in a tweet.
“Some of them are luck or unlucky where these fires broke out, especially the grizzly leak fire, which wasn’t that big, but it’s located next to the I-70 and on its steep terrain. So, in fact, this is one of the areas most affected by the floods this summer, “Bolinger said.
The grizzly leak fire burned 32,000 acres inside and outside Glenwood Canyon last year. At the same time, there was an East Trouble and a Cameron Peak fire. Became the state’s two biggest flames in state history..
The landslide was triggered earlier this week along the burn scars on Cameron Peak. More than an inch of rain fell near Crown Point, and debris flowed into the Poodle River near Black Hollow Road, upstream of Rustic Village.
One died and several were reported missing As of Friday, flash floods sent debris flowing into the Poodle Canyon northwest of Fort Collins. Trees, mudstone, rocks and structures flowed into the river, destroying several homes, damaging buildings and depositing 6-foot-high debris in some places.
Part of Colorado 125 and US40 in Grand County closed Annoying burn scars a few hours Thursday after a landslide fell along the east.
But sometimes it doesn’t have to rain a lot for a flood to be a disaster.
“There is no perfect relationship between the amount of rain you get and the level of flooding. Even if you don’t expect heavy rain, that may be enough,” Bollinger said. “Even a little rain can quickly change the situation you are in, so you want to see what you are doing.”
Rain-wet landslides are not limited to burned areas. Telluride heavy rain And Avon filled roads and pedestrian trails this week In the rubble.
How long do you need to predict the risk of flash floods?
Flash floods, especially along the burn scars, can last until the monsoon season, which normally lasts until September, Bollinger said.
“When we look at the forecast, seeing thunderstorm activity predicted in any of these burn scars is at risk of another flood event soon,” she says. I did.
Where are the areas facing the greatest risk of flash floods this weekend?
According to the National Weather Service’s Boulder office, widespread thunderstorms are predicted throughout the highlands from Friday afternoon to evening.
Flash flood surveillance is being conducted until 9 pm in some areas, including East Trouble, Cameron Peak, Grizzly Peak, and burn scars from the Calwood fire, officials said.
According to the Meteorological Bureau, it is expected to rain 1 to 1.5 inches per hour in some areas.
The Meteorological Department warned that water levels and effluent flow rates could change rapidly during floods. If you get caught in flash floods, you’ll need to look for hills and check local weather forecasts on the radio and news to monitor weather conditions, the Meteorological Department said. People should not walk or drive in high water.
“When driving in the mountains, it’s good for people to know that they really need to know the risks of natural disasters they may face,” Bollinger said. “Flash floods are probably something you should know every summer, but they are even more of a problem, especially when driving near burn scars.”
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Mudslides and flash flooding along Colorado’s burn scars could cause disasters all summer long. Source link Mudslides and flash flooding along Colorado’s burn scars could cause disasters all summer long.