Where do rivers flow?
All rivers are surrounded by a certain amount of land that is higher in altitude (upgradient) than the actual river. Precipitation that falls in this area eventually flows downhill towards the river. At any particular point on a river, the land upgradient of the point is the river’s drainage basin (often known as the watershed). This example of a drainage basin gives a rough idea of how precipitation flows downhill into rivers (and lakes). [ EPA Watershed Interactive Website] Which direction do rivers flow? What separates two drainage basins from each other are ridges of higher land. The Continental Divide, runs along the highest ridges of the Rocky Mountains. Precipitation falling on the western side of the Divide will flow towards the Pacific Ocean and precipitation falling on the eastern slopes will flow towards the Atlantic Ocean, via the Gulf of Mexico. The United States has many drainage basins of many sizes, and many, many ridges that define these drainage basins. In Atlanta, Ga
