Watersheds and Rivers

Watersheds & Rivers

It is very simple to explain why rivers exists on Earth— gravity! You’ve familiar with “water seeks its own level,” but in reality, water is seeking the centerpoint of the planet, just like everything else is. In more practical terms, water usually seeks to flow directly to the oceans, which are, of course, at sea level. So, wherever on Earth water is, it attempts to flow downhill. With the planet being a very not-level place, water ends up filling the valleys and depressions in the terrain as rivers, streams, and lakes.

When observing the location of rivers and streams and the amount of water flowing in rivers, the key idea is the river’s “watershed”. If you are standing on level ground right now, just look downward. You are standing, and others are standing, within a watershed. To define a watershed, it is the region of land where all water falls into it and it drains away as it goes to the same place. Watersheds are be as small as a footprint or massive enough to engulf all the lands that drain water into the rivers,  that drain into the Bays of the Ocean. Bigger watersheds almost always contain multiple smaller watersheds. It is all dependent on the point of outflow; all of the terrain that drains to the outflow location is the watershed of that outflow location. Watersheds are vital because the river-flow and the quality of water of a river are impacted by things, human-induced or not, occurring in the land area “upstream” of the river-outflow point