The term upriver (or upstream) refers to the direction towards the source of the river, i.e. against the direction of flow. Likewise, the term downriver (or downstream) describes the direction towards the mouth of the river, in which the current flows.

Can rivers flow upstream?

Rivers tend to flow downstream, but sometimes they don't. Sometimes they flow sideways and sometimes they flow upstream! ... Rivers flow because water falls, due to the effect of gravity.

How does the river flow downstream?

The word downstream (which is one word instead of being two words; down stream) mainly means the direction that the water in a river flows. Downhill, towards the sea, or nearer to the mouth of the stream (where the river ends). It can also be known as downriver.