Flooding events a major concern for Grand County following #EastTroublesomFire — The Sky-Hi Daily News #ColoradoRiver #COriver #aridification

The map above displays estimates of the likelihood of debris flow (in %), potential volume of debris flow (in m3), and combined relative debris flow hazard. These predictions are made at the scale of the drainage basin, and at the scale of the individual stream segment. Estimates of probability, volume, and combined hazard are based upon a design storm with a peak 15-minute rainfall intensity of 24 millimeters per hour (mm/h). Predictions may be viewed interactively by clicking on the button at the top right corner of the map displayed above. Map credit: USGS

From The Sky-Hi Daily News (Amy Golden):

One of the biggest concerns following the East Troublesome Fire in Grand County is flooding risk, specifically flooding that picks up debris to create mudflows. Local and national officials are working to get the word out about this new risk and prepare Grand County for a changed landscape this summer…

A number of watersheds were burned in the East Troublesome Fire, including 94% of the Willow Creek Watershed, 90% of the Stillwater Creek Watershed, 42% of the North Inlet Watershed and 29% of the Colorado River Watershed.

Projections have found that water flow from snowmelt and weather events on the burn scar could be 14 times higher than before. According to Grand County Emergency Manager Joel Cochran, the National Weather Service will be monitoring rainstorms that produce even a little bit of rain…

The US Geological Survey has also produced preliminary hazard assessment across the East Troublesome burn scar. The assessment found that most of the water basins in the burn scar present a moderate risk of debris flow hazards with a high risk in certain areas.

County officials have been working to identify specific risks to property and life.

The first part of that included field surveys for damage assessments, which were completed last week. Using additional modeling, risk for various structures have been further assessed and officials are working to communicate that hazard to land owners.

In her Tuesday update to commissioners, Grand County Water Quality Specialist Katherine Morris added that some narrow canyons and roads near flowing water would likely need formal evacuation plans.

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