Storms now pounding Southern California are raising the specter of more danger for residents -- debris flows in areas already reeling from devastating fires. Debris flows are like mudslides, except much faster and more destructive, as they contain a mix of rock, plants and even boulders or trees in addition to mud.
Andrew Gray, an associate professor of watershed hydrology at UC Riverside, is an expert on the way water and sediment move through landscapes after wildfires. He weighs in here on the threats to life and infrastructure posed by these fast-moving flows, and how residents can best respond.