It’s remarkable. Even on large mesa tops flooding can be severe. There is no “soil” to begin with as we understand it. Just sand, and sandstone eroded into weird spires and alcoves, bone dry most of the time. But when it does rain, there is little absorption at all. It builds up into a raging torrent with astonishing speed.
In the slot canyons it is particularly dangerous because there might not be any rain or even clouds in the immediate area.
As I understand it, it can rain hard 100 miles away and be sunny in the Canyon which will then get an onrush of water through the lowlands and canyons.
I’ve seen videos and they are frightening even just watching. The “water”comes fast like a wall of thick tomato soup plus logs and rocks with it.
Yup.
Like the Antelope Canyon disaster in 1997.
An interesting video on this topic.
US Said This Desert Canyon Was Lost — Then 15 Piles of Rocks Built in 1933 Brought the Water Back
Deep inside Saguaro National Park in Arizona, small rock-and-cement check dams built during the Great Depression are still changing how water moves through the Sonoran Desert. Beginning in 1933, young men from the Civilian Conservation Corps (CCC) constructed these masonry barriers to fight severe erosion—and decades of accumulated sediment eventually created something unexpected: persistent water in one of North America’s driest landscapes.
This documentary explores how the Civilian Conservation Corps check dams helped restore degraded desert canyons after decades of overgrazing had stripped vegetation and accelerated soil loss. Unlike conventional dams, these structures were never designed to permanently block water. Their purpose was simpler: slow violent monsoon runoff, reduce erosion, and trap sediment.
Over successive storms, layers of sand, clay, and fine material accumulated upstream. That porous sediment began acting like a natural underground reservoir, absorbing monsoon water and releasing it gradually long after the surrounding desert surface had dried. The script traces this process to a spring near the historic structures, surrounded by greener vegetation and concentrated wildlife.
Nearly 90 years of monsoons, extreme heat, and winter freezes have tested structures built largely by hand from materials found directly in the canyon. Their story connects the Civilian Conservation Corps, Saguaro National Park history, Sonoran Desert restoration, check dams, erosion control, sediment capture, water harvesting, groundwater infiltration, watershed restoration, and drought resilience.
• How Civilian Conservation Corps workers built small masonry check dams in Arizona beginning in 1933
• Why slowing monsoon runoff allows sediment and water to accumulate instead of disappearing downstream
• How decades of sediment deposition can create localized water storage, vegetation recovery, and desert habitat
We explore ecological restoration, water recovery, conservation history, rewilding, and overlooked projects that have transformed damaged ecosystems around the world.
Yeah