7.1 A River Runs Through It

Where does your water come from?

Step 1: Go to the ArcGIS Online map, A River Runs Through It, and explore the map.

Step 2: In the upper-right corner, click the link, Modify Map.

Step 3: With the Details button underlined, click the button, Show Contents of Map (Content).

Step 4: In the Find Address or Place box at the top right of the map, search for your home address.

  • What is the largest lake or river near where you live?

Step 5: Looking at the water nearest you on the map, trace how it flows eventually to a sea, ocean, or bay.

Step 6: Make a list of the streams and rivers your local creek flows into before making it to the bay, sea, or ocean.

How removed are you from the ocean?

As rivers split farther upstream, each side-branching stream or tributary is assigned a higher stream “order” number.

Step 7: Using the list created above, count backward from the farthest tributary to determine which stream order a local creek outside your school is considered to be.

What makes up an entire watershed?

As part of the global hydrologic cycle, water evaporates from oceans, lakes, or rivers (or from plants or soil) and falls across continents. Because water is a fluid, it flows along a downhill path that eventually leads back to the ocean. All the areas draining into a single river system are known as that river’s watershed.

Step 8: Click the Edit button, and then click Areas to draw around each of the major rivers. Draw around the Mississippi River, including all rivers draining into it as part of the watershed. Draw around the watershed of the Columbia River in Washington. Draw around the watershed of the Colorado River in the southwestern United States. Draw around the watershed of the Rio Grande River along the border of Texas and Mexico.

Step 9: To check your work, zoom in two clicks to see the smaller regional river watersheds.

Can you find watersheds through the network of connected rivers?

Step 10: Turn on the layer, World Shaded Relief.

  • Where do most rivers start?

Step 11: Click the Hudson Bay Watershed bookmark.

Step 12: Click the button, Edit.

Step 13: Click the map at the upper edge of the Mississippi watershed (between Canada and the states of North Dakota and Montana), and continue drawing around the area of all rivers that drain into the Hudson Bay. You can use multiple smaller lines to create the boundary. Choose the Areas tool again for each section of line you want to draw on your current view of the map before panning.

Step 14: Continue drawing lines north along the Rocky Mountains to find the edge of where the rivers drain into the Hudson Bay and those that drain north into the Arctic through the Mackenzie River system. For a solution to the major North American watershed boundaries, turn on the layer, Watersheds.

What do other watersheds look like?

Step 15: Choose another extensive river system on another continent that is unfamiliar to you.

Step 16: Use the World Rivers and World Shaded Relief layers to guide where to draw the edges of the watershed.

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