Alluvial fan flooding

Flooding that occurs on the surface of an alluvial fan (or similar landform). An alluvial fan is the area at the base of a valley where the slope flattens out, allowing floodwater to decrease in speed and spread out, dropping sediment over a fan-shaped area. This type of flooding is characterized by high-velocity flows; active processes of erosion, sediment transport, and deposition; and unpredictable flow paths.