think or thwim

This is not what I expected. I’d imagined a fast moving wall of water, but this stuff looks like lava.

Kellick Creek at Ringwood Road Crossing southwest of Merriwa, NSW, Australia [Google Map]:

Wahweap drainage (in Arizona?):

These videos weren’t taken by him, but David Rankin films flash floods for fun. From his site:

Also, as a hobby, I chase, predict, and capture Flash Floods on video. I am fascinated with the amazing destructive power these floods have. 1 inch of rain over 1 square mile amounts to over 17.38 million gallons of water that need to be drained. Some of the floods in these videos were produced when 2 - 4 inches of rain fell over 30 square miles, over a billion gallons of water draining down one wash in the desert. These washes are usually bone dry for most of the year until the monsoon rains come.

He has a DVD of his flood films for sale. There’s a sample on his site.