An alluvial fan is a landform created by the deposition of sediment as water flows from a steep area to a flatter region. This process occurs when a river or stream loses energy, causing it to drop its sediment load. The fan shape typically spreads out in a triangular or fan-like pattern, with the apex at the point where the water exits the mountain or hill. Alluvial fans are commonly found in arid and semi-arid regions, where intermittent streams flow from mountains. They can be important for agriculture, as the sediment deposited can enrich the soil. Additionally, they often serve as natural flood control features, helping to manage water flow in surrounding areas.