Images

Interstate 70 in Glenwood Canyon, Colorado. In the summer of 2021, travelers in Colorado's Glenwood Canyon were safely evacuated before massive debris flows buried highways and destroyed bridges, thanks to a debris flow warning system developed in part by the U.S. Geological Survey.

USGS scientist assesses debris flow in Glenwood Canyon, Colorado. This post-wildfire debris flow follows the 2020 Grizzly Creek Fire. 

Kelli Baxstrom excavates a pit for sensor installation at a monitoring site in Maricao, Puerto Rico.

Rockslide on California State Route 70 in the Feather River Canyon, Butte/Plumas county line, northern California. This slide was triggered on October 24, 2021 by a Category 5 atmospheric river, which released more than ten inches of rain in the area over a 48-hour period. Approximately seven thousand cubic yards of rock and debris buried and closed the highway.

The USGS “Chambers” site is located in the Plumas National Forest in northern California. The site consists of instrumentation monitoring the hillslope in the lower part of the image. The hillslope exhibits moderate soil burn severity and hosts sandy soils derived from granitic bedrock.

The USGS “Chips” site is located in the Plumas National Forest in northern California. The site consists of instrumentation monitoring the hillslope in the lower part of the image. The hillslope exhibits moderate soil burn severity and hosts silty soils derived from metamorphic bedrock.

Debris flow caused by intense rainfall from Tropical Storm Fred in August 2021. Haywood County, NC. 

The hillslopes above Cinnamon Creek within the Grizzly Creek burn area one year following the Grizzly Creek fire.  

Hillslope recovery along Blue Gulch in the Grizzly Creek burn area.  This photo was taken approximately 1 year following the Grizzly Creek fire. 

Ground level view of debris covering the eastbound lane of I-70 following the June 26-27, 2021, storms. The green sign in the background indicating Milepost 120 is mostly buried by mud.

2020 Calwood Fire burn area, Boulder County, Colorado. This overview photo looking west from the ridge separating the 'Calwood' side of the burn area from the 'Heil Ranch' side.  The photo was taken approximately 7 months after the fire, which occurred in the fall of 2020.

A scientist installs a hillslope monitoring station in the 'Heil Ranch' section of the 2020 Calwood Fire burn area.  Hillslope monitoring stations collect data about rainfall and soil properties, and record debris flows that occur in burned watersheds.  

Burned hillslope in the 2020 Calwood Fire burn area, Boulder County, Colorado.  This hillslope sits above a very small drainage area and is still devoid of vegetation approximately 7 months following the fire.  Small rills or incisions on the slope formed in areas where runoff became concentrated.  

Overview photograph of the area burned by the 2020 Calwood Fire in Boulder County, Colorado.  The hillslopes are covered by burned tree remnants and boulders. In this view, very little vegetation has returned.  

Approximately 7 months following the Calwood Fire, Boulder County, Colorado vegetation begins to regrow on the burned hillslope.  

Rain Gauge installed after the 2020 Grizzly Creek fire in Glenwood Canyon, Colorado. Scientists installed a network of rain gauges and soil moisture sensors throughout the rugged burn area. These instruments provide real-time data on rainfall intensity and duration, which are critical factors in determining the likelihood of a debris flow. 

Rain gauge in Glenwood Canyon, Colorado. After the 2020 Grizzly Creek fire, scientists installed a network of rain gauges and soil moisture sensors throughout the rugged burn area. These instruments provide real-time data on rainfall intensity and duration, which are critical factors in determining the likelihood of a debris flow. 

Rain gauge installed in Glenwood Canyon, Colorado. After the 2020 Grizzly Creek fire, scientists installed a network of rain gauges and soil moisture sensors throughout the rugged burn area. These instruments provide real-time data on rainfall intensity and duration, which are critical factors in determining the likelihood of a debris flow. 

Three soil moisture sensors shown before their installation in a soil pit. The sensors will form a vertical subsurface array geared to track infiltration behavior. 

This photograph of a small watershed within the 2020 Calwood Fire burn area, Boulder County, Colorado was taken 6 months following the fire.  The removal of vegetation and change in soil properties make steeply burned areas susceptible to postfire debris flows.  

Soil pit shown with three soil moisture sensors installed in a subsurface vertical array. The wetting and drying of the soil will be tracked over multi-annual timescales.