A drainage divide is a geographical boundary separating neighboring drainage basins, where precipitation on either side of the divide flows into different bodies of water. Drainage divides can range from sharp ridges, such as mountain crests, to subtle topographic boundaries. They are crucial in hydrology, determining the direction of water flow and influencing river systems.
Reference: Twidale, C. R. (2004). “River Patterns and Their Meaning.” Earth-Science Reviews, 67(3-4), 159-218.