1. a smaller drainage basin that is part of a larger river basin or watershed
Usage: geography; hydrology

Examples

• The Colorado River basin contains several major subbasins.
• Scientists studied water flow patterns in each subbasin separately.
• The northern subbasin receives more rainfall than the southern region.
• Urban development has altered the natural drainage in this subbasin.
• Each subbasin contributes differently to the main river’s flow.
• The map shows five distinct subbasins within the watershed.