Location of the six major river basins within the River basin.

Map Exploration - Watershed CPR

What Is a river basin? - Quora

Arctic Change - Land: Rivers

Six major river systems in India considered in the study

Watersheds of North America - Wikipedia

NASA SVS The Rivers of the Mississippi Watershed

San Joaquin River Basin

Mapping the World's River Basins by Continent

Basin

OVERVIEW — South River Watershed Alliance

Potomac Basin Facts - ICPRB