Back when I was a youth, I visited a friend who was stationed at White Sands in NM. As I was driving down there through the desert, I had noticed white sticks with numbers, usually1-5, posted along the roads. I asked him about that, and he told me that’s so drivers know how deep the water is across the roads. He then showed me a couple of dams out in the middle of the desert and a topographic map of the area.
I got it.
The first time I was ever in Phoenix I was down there going to work out at Palo Verde NGS. So they gave me directions and told me to head west and “cross the river” and so on and so on. So I start driving down the road I was supposed to be on and kept driving but never crossed a river. So I turn around and go back and they say that there is no river but the dry river bed that the road drops into and across!
Never seen it flood in person but have seen many videos of that area since and it flat gets to rolling!