What Is River Capture (Stream Piracy)?

River capture occurs when one river system diverts the headwaters of another. Two main mechanisms:

• Stream Piracy: A more aggressive tributary erodes through the drainage divide, capturing the rival's headwaters. Often due to steeper gradient, softer rock, or lower divide.
• River Diversion: A natural event (landslide, lava flow, glaciation) blocks a river, forcing it into a neighboring basin.

Consequences: altered drainage patterns, changed sediment load, modified aquatic habitats, shifted water chemistry. The captured stream's valley often becomes a "wind gap."