There is evidence also that glacial moraine formations from time to time may have largely affected the catchment area of these tributary streams. It would be as rash to assert that from Lake Victoria no waters could ever have issued with an eastward flow as it would be to state that 'from Chakmaktin none ever flow westwards.
The whole of the land which directs drainage towards one river is known as its basin, catchment area or drainage area - sometimes, by an incorrect expression, as its valley or even its watershed.
The catchment area from which the Caspian is fed extends to a very much greater distance on the west and north than it does on the south and east.
The plateau or highland region which forms the waterparting between the Tarim basin on the east and the Syr-darya catchment area on the west.
Suffice, for there is no sufficient catchment area north of the snows to support it.