It might be considered a creek or stream.
A small, flowing body of freshwater is called a stream. Streams may also be called a: brook, creek, bayou, rivulet, wash, or run.
It could be a river.
Oasis.
oasis
Oasis.
Oasis.
stream
The Nile is a north-flowing freshwater river.
A mountain stream, or a river flowing lower down in the valley.
A stream, a small body of flowing water.
It is a fresh water stream.
An oasis is a small body of freshwater found in the middle of a desert. These areas often support vegetation and wildlife and provide a source of water for travelers and local flora and fauna in arid regions.