Introduction to a Watershed

Inspiration

Ask students to imagine themselves in a small airplane on a long flight across vast and varied terrain.

Ask students how the rivers they saw were similar to one another. In what ways were they different? Did the width of the channel vary from one image to the next? Did the width change within any one image? How do they explain this variation? Did they see only the river? How did the surroundings of the river affect the picture they saw? What does the word "basin" suggest? In what ways does the word "basin" relate to their images of the river?

Re-image one of the rivers and river basins. Create a healthy and hearty rainstorm of considerable duration. Watch it rain over your entire basin. Imagine it raining on every inch of the terrain. Follow one raindrop down to one particular place. The ground is now saturated. The drop will "run off." Where does it go? Follow it out of the frame of your picture. Follow others falling at different locations. Is all the water moving at the same speed? In what areas does the water hurry? In what areas is it lazy? How does it change as it "goes somewhere"?

Focus

What you are imagining here is a drainage basin or watershed. It has, of course, component parts and processes particular to watersheds. A watershed is the land that water flows across or under on its way to a stream, river, or lake. The landscape is made up of many interconnected basins, or watersheds. Within each watershed, all water runs to the lowest point, a stream, river, or lake. On its way, water travels over the surface and across farm fields, forest land, suburban lawns, and city streets, or it seeps into the soil and travels as ground water.

It has been said, "Everyone and every thing lives in a watershed." Is this true? How about a scorpion in Death Valley? An Antarctic penguin? Is everyone and every thing dependent upon some watershed? Can you think of exceptions?

Keeping this quotation in mind, look at local, continental, and global watersheds and see if your findings support or dispute the quote.

Reflection

"A river is really the summation of a whole valley. To think of it as nothing but water is to ignore the greater part." -Hal Borland

Read only the first sentence of the quote to students. Do you agree? What are the component parts of the sum?

Read the second sentence to students. To "see" a river as Hal Borland suggests it be seen, what, in addition, to the water in the river, would our senses have to take in?

Can you remember really "seeing" something, perhaps something very common to you, for the first time? A flower; an insect; a parent; a problem; etc. What were the circumstances that allowed you greater vision in this instance?

Creation

Discuss briefly the local watersheds and the bodies of water into which they flow. Introduce the term "divide" and, using local maps, have students identify "divides" for particular local watersheds.

Have students use an almanac to make a list of the 15 largest cities by population in North America. Using a map of North American Rivers, have students identify the continent's major rivers, waterways, and large bodies of water. Without consulting an atlas, have students attempt to correctly place as many of those 15 cities as they can. Check accuracy with an atlas. Discuss the relationship they see between large population centers and waterways.

Label all major rivers shown on the map and sketch in major topographic features that determine the direction of flow. Also label all bodies of water into which the rivers flow.

Repeat the same procedure using a map of major watersheds of the world (one without the river names labeling the watersheds). Identify the 10 cities of largest population outside of those cities in North America. Attempt to locate them on the map without the aid of an atlas. Now, consult the atlas, locate correctly, and discuss city placement relative to waterways.

Using an atlas, invite students to identify the major rivers that drain the watersheds shown on the map. Which are the five largest watersheds? Which of the rivers have you never heard of? Which are most familiar to you? What accounts for the familiarity with some and lack of familiarity with others?

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