Flash floods are definitely gonna kill people, so here’s your regularly scheduled PSA:
Desert soil does not absorb a significant amount of water. It reaches maximum saturation very very quickly, and all the rest of the water rushes downhill. Even if you can’t tell that the ground is not perfectly flat, the water can. And it will move. Quickly. No, faster than that. Nope, still faster. If you try to cross moving floodwater, you will get swept downstream and probably die.
Do not try to wade in/cross flood water that is any deeper than the thickness of the sole of an average athletic shoe, no I am not kidding, the water will get deeper literally while you’re standing in it.
This goes for cars, too. I’ve seen entire vehicles getting swept downstream in flash floods because the driver thought they could cross the “puddle” and Found Out.