Watershed

• Geographic area through which water flows across the land and drains into a common body of water, whether a stream, river, lake, or ocean
• Watershed boundary will more or less follow the highest ridgeline around the stream channels and meet at the bottom or lowest point of the land where water flows out of the watershed, the mouth of the waterway

Drainage basin

• Also known as catchment basin
• An area of land where surface water from rain, melting snow, or ice converges to a single point at a lower elevation
• Usually converses at the exit of the basin, where the waters join another water body viz. river, lake, reservoir, estuary, wetland, or sea
• Hence it is an area drained by tributary streams that coalesce into a main channel

Watershed Divide

• The line, which divides the surface runoff between two adjacent river basins, is called the topographic water divide, or the watershed divide.
• It marks the highest points between the basins, but isolated peaks within a basin may reach higher elevations than any point on the divide.