Hiking a picturesque valley or climbing a craggy gorge are some of the most exhilarating experiences in nature. As a geologist, I have hiked and climbed some of the most intense terrains in the world, including in the Andes, Middle Eastern deserts, the Balkans and the Appalachians.

I am particularly drawn to canyons that provide beautiful windows into the rock record and the geologic history of a place. However, these narrow valleys can quickly become extremely dangerous when water pours in.

At Grand Canyon National Park in Arizona, at least two hikers died and a third was missing after powerful monsoon storms sent a deluge into one of the narrowest parts of the canyon on Aug. 29, 2026. Two of the survivors who were rescued described seeing the water quickly rise over the trail as they clung to a ledge, fearing they might never see their families again.

So, how do you balance a love for outdoor activity with managing this risk and hike canyons safely?

Why canyons are prone to flash floods

To understand the dynamics of a flash flood, it helps to start with the geomorphologic aspect – understanding the landforms and how they change over time.

In canyons and arroyos – steep gullies common to the Southwest – flash flooding can occur even when the heavy rainfall happens great distances away. A person can........

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