In normal times, the creek stays within the banks of the creek bed.
For the most part, this works.
Water runs through the bottom of the canyon under cottonwoods, footbridges, and campsites that have sat there for decades.
But then, the channel changed.
Flash flooding occurred down Bright Angel Canyon at approximately 2:30 p.m. on August 29 and washed so fast through the canyon to create new channels in a matter of hours.
One week later, a drone flew along the canyon.
What it recorded was the path that the water took.
Why floods become destructive inside a narrow canyon
There isn’t much room for water to spread when you are in a canyon.
That is the first obstacle.
Anytime heavy rainfall occurs above the canyon, runoff is funneled into the same tight space as the creek.
The water picks up speed.
Anything that comes with it (debris) follows the creek.
Trees, rocks, and sediment travel downstream together, creating a rapidly moving wall instead of a rising creek.
Bright Angel Canyon increases that effect by narrowing the space available and forcing runoff into a single tight path containing trails, bridges, and park buildings.
Danger develops rapidly.
People standing on dry land may find the canyon looking completely different within minutes.
Speed is why floods caused by rain falling in canyons are treated differently from common rainstorms.
What the flood actually destroyed
Nearly all foot bridges crossing over Bright Angel Creek were destroyed.
The entire trail system relies on these crossings.
Without them, large areas of the canyon will be impassable.
Both Phantom Ranch and Bright Angel Campground were affected. The National Park Service reported that the North Kaibab Trail remained closed, while portions of the South Kaibab, Bright Angel, Tonto and Plateau Point trails remained accessible.
The Black Bridge and Silver Bridge across the Colorado River were both closed.
By the next morning (August 30), 62 individuals had been removed from Phantom Ranch and the lower portions of the North Kaibab Trail.
Additional removals were conducted from Phantom Ranch and Cottonwood Campground.
By early September, two people had died in the flood, and one person remained missing.
On September 1st, park personnel assessed damage to parks utilities, buildings, bridges, and paths along the length of Bright Angel Canyon.
Flood debris and metal structures created problems on the river, which led to the closure of river traffic through that area.
Inside the flood corridor a week later
September 6th saw another flight along the canyon starting near Bright Angel Campground.
Aerial photography demonstrates scale. It does not demonstrate force.
A drone may show where sediment ended up.
It will never be able to clearly illustrate what velocity would have been necessary to rip out bridges that have endured numerous seasons of regular flooding.
The aerial photographs captured conditions on September 6, eight days after the event, not conditions during the deluge.
In addition to ongoing rains causing potential additional flash flooding, rockfall, mudslides (debris flows) remain potential hazards in the weeks ahead.
Why the missing bridges matter most
The missing bridges tell the true story. Trail repairs and debris cleanup can occur. Repairing a destroyed crossing is significantly more difficult.
Every piece of material needed to repair or replace destroyed crossings must first arrive at the canyon.
Like visitors, workers and equipment face similar obstacles accessing the canyon.
A footbridge appears tiny against the backdrop of the Grand Canyon walls until it is gone. Once it is gone, routes, transport, and emergency access can disappear with it.
A creek that deviated from its normal path for a couple of hours greatly impacted a significant portion of the canyon used as one of the top hiking corridors in North America.
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