TIL wildfires can makes floods much, much worse. This morning I was listening to a podcast interview with a guy who's a geologist & hydrologist who lives in Arizona and studies its water. He said he lives in the Colorado River valley, upriver from Flagstaff. Sometime last year there was a wildfire up in the hills/mountains (somebody was burning toilet paper?) that wiped out the vegetation on the watershed uphill from the town. Then the seasonal rains came, heavier than usual. He said the culvert alongside his house is rated for 50 cubic feet of water per second, and estimated it was getting 300 cubic feet per second. He said there was a "mud geyser." He said the estimate was that the town got 30 times as much water as it normally does during these seasonal rains, mostly owing to the destruction of the thirsty desert vegetation. He also noted that the water coming down from the fire-ravaged hills was black with soot, in addition to carrying all of the usual debris with it, making the cleanup afterwards even tougher.
He didn't mention any mudslides. I think I've read before that wildfires that strip the hills of vegetation can cause big mudslides when the rains come. I want to say that happened in Brazil a few years ago and, like, wiped a whole town off the map. In that instance, I believe the roots of the vegetation literally held the side of the hill in place, and after the fire it was just bare dirt. For some reason, I hadn't connected the dots, vis-a-vis flooding, particularly in desert areas where the plants absorb enormous amounts of water in a short time.
