the.com/drainage basin

means The entire area of land where all the rain, streams, and groundwater drain downhill into a common river, lake, or sea.

from Straightforward compound, not a myth in disguise: 'drain' traces back to Old English 'drēahnian' (to strain or draw off liquid), and 'basin' comes via Old French 'bacin' from Vulgar Latin 'bacinus,' a wide bowl-like vessel. Geographers borrowed 'basin' for landscape because a watershed, seen on a map, really does look like a great shallow bowl tipped toward one low point — so the term is less a coinage than an honest piece of descriptive geology.