What Makes a Watershed?

This image shows a watershed.

Water enters the watershed as precipitation. It then soaks into the ground by infiltration and becomes part of the groundwater. It may also flow downhill as runoff over the ground until it enters the stream's surface. In the picture, the watershed is everything within the yellow dashed line. If the name of the stream is Brooker Creek, then the watershed is called the Brooker Creek Watershed. Likewise, everything that drains to the Mississippi River is called the Mississippi River Watershed (or Mississippi River Basin). Click to enlarge the watershed image and then roll over the image to learn about six watershed components.

What do you notice about the layout of the land? Why is the stream located where it is?

The land is bounded by areas of high elevation and the water flows downhill from the force of gravity. Eventually, all of the water makes its way to the lowest point and collects there.

You know the streets that make the boundaries of your neighborhood and the roads that border your hometown. What makes the boundary of a watershed?

Watersheds are bounded by areas of higher elevation. The boundaries are the highest points that surround a body of water.