Wind!
The rivers of western Europe flow toward the Atlantic Ocean and the North Sea.
In North America, rivers located east of the Continental Divide flow toward the Atlantic Ocean, the Gulf of Mexico, or the Hudson Bay. The Continental Divide serves as a natural boundary that directs the flow of water; rivers on its eastern slopes generally move toward these bodies of water, while those on the western slopes flow toward the Pacific Ocean. This geographical feature plays a crucial role in the hydrology and ecosystems of the region.
Gravity causes the water to seek it's own level - the sea level! Directionally speaking, they flow from the northwest toward the southeast.
Tributaries
a delta
the Atlantic ocean
The Arctic Ocean
Candy
Small streams flow into rivers and the rivers flow to bigger rivers.
All of the rivers in Siberia tend to flow north. These rivers flow north as they being pulled to drain into the Arctic Ocean.
It has no 'purpose' it is a natural occurring division. The continental divide is a line that runs down through the Rocky Mountains and on the west side of the line rivers and streams flow down toward the Pacific Ocean and on the east side of the line rivers and streams flow towards the Atlantic Ocean.
Pacife