Source: American Geophysical Union.
Adapted with permission.
Watersheds can be as small as a lake or thousands of square miles. The natural or human-made surface of the land and the sediments and rocks below are all part of a watershed. Rainfall
supplies watersheds, and water moves across the surface or infiltrates and moves through the ground.
In this activity you will use a computer model to explore the movement of water within your watershed.
• Computer with internet
1. Getting to know your watershed: Geometry and scales of streams.
• Open Model My Watershed: https://wikiwatershed.org/model/.
• Navigate to your local area.
• Click “Select by boundary.” Choose USGS Watershed unit (HUC-10).
• In the Layers list, select “Continental US Medium Resolution Stream Network.”
• Zoom out. Identify your local watershed. Which rivers are familiar?
• Double click a river to bring up the “Analyze” section for Stream Network Statistics.
• What is meant by stream order? Describe the results for stream order.
• What happens to the relative amounts of evapotranspiration, runoff, and infiltration as the amount of rainfall increases?
• Is there a point at which this relationship breaks down? Explain.
• In which fraction, evapotranspiration, runoff, or infiltration do you think the suspended solids, nitrogen, and phosphorus would be found? Explain.
• What happens to the amounts of each as precipitation increases? Why?
• Describe possible effects of changes in the amounts of total suspended solids, nitrogen, and phosphorus?