Yes, Rivers Can Flow North!
A Lesson on Watersheds
By Timothy McDonnell
New York Geographic Alliance
Monroe Community College
Rochester, New York
Grade Levels: Upper Elementary and Middle School
Objectives:
1. To define these geographic terms: watershed, tributary, divide, source,
outlet, drainage area.
2. To demonstrate that the rivers can flow in any compass direction, but
they always flow downhill.
3. To make models of watersheds and to compare them to real river
systems.
Materials: compass directions displayed on the walls of classroom,
cardboard (or foam board), plastic tubing, funnel, cups, world map or atlas,
construction (or some other stiff) paper, markers, food coloring (optional),
dice, graph paper, river map of the United States, river map of New York
State.
Procedures:
1. Make a simple “river,” that is gently sloping (see the drawing on page
4), using cardboard (or foam board), plastic tubing, and funnel, and a
cup to catch water.
2. You should the four cardinal directions displayed in the classroom.
Point your river model “south.” Pour water down the funnel, and
discuss what happens with the students.
3. Repeat this process so the river flows east, west, and north. Discuss
what this means with the class. Can rivers flow in all directions?
4. Now tilt your river so it slopes uphill. What happens now? Try it in
other compass directions. Does it flow or not?
5. What must we conclude? Are “north” and “up” the same? Are “south”
and “down” the same?
6. Find the Mississippi River on a map. It flows from Minnesota the
Gulf of Mexico (near New Orleans). What direction is that? This
means that Minnesota is at a higher elevation than the Gulf of Mexico.
7. Repeat step 6 with the Nile River (Africa), the Yangtze River (China),
and the Columbia River (Washington/Oregon). What conclusion must
we make?
8. Rivers are parts of systems or watersheds. This is something that
needs to be modeled. First, give each small group of students a piece
of stiff paper (construction paper works well). Write the four cardinal
directions on the paper. Then, have them crumple the paper gently.
Then they should pull the paper out again, so there “mountains” in the
middle. Tape the paper to the desk surface.
9. Tell the students that this is an “island,” and their desktop is the
“ocean.” Using markers, they should trace the ridges along the high
points. These are divides. Using a different color, they should trace
one main “river” down the slope to the ocean. Then they draw in the
tributaries that connect to this main river. This is a watershed. They
repeat this process until they have several watersheds sketched on the
paper.
10. Optional: They can test this model out by rolling a marble down the
map. For each watershed, the marble should roll in a different
direction, but always downhill! Or, for older students, they can try
dripping diluted food coloring down the slides of the mountains
instead of using markers.
11. Another model of a watershed map is made by using dice and graph
paper. Have the students work in pairs. Give them a copy of page 5.
Notice that there a dots (sources of rivers) located just inside the
divides. They should turn the paper so the ocean side faces them. Start
with any dot. One student rolls a die. His/her partner draws a line in
one graph square as follows: 1 - down diagonally left; 2 – down
diagonally right, 3 – squiggly line straight down; 4 – an S- curve
down; 5 – a horseshoe-shaped loop left; 6 – a horseshoe-shaped loop
right. See p. 5 for an illustration. When the river reaches the ocean,
stop!
12. Pick another dot, and repeat step 11. However, if the second river
meets the first river, stop there. It becomes a tributary. To make it
look more realistic, trace over the river from this point to the sea, so it
is wider (more water in it). Keep going until all dots are used up. If
this river has six tributaries then it should be very wide by the time it
reaches the sea.
13. How close to real river systems is this model? Compare it to the
Mississippi River Watershed (p. 6). Have them trace the river with a
marker from its source at Lake Itasca in Minnesota to its delta in the
Gulf of Mexico just south of New Orleans, Louisiana. Then draw in
all tributaries of the Mississippi. (It’s easier to work backwards from
the river to the source). Then they should draw a dotted line around
the entire watershed.
14. Optional: They can do other watersheds on this map: Colorado,
Great-Lakes/ St. Lawrence, Rio Grande, Columbia. If you do this
activity, then you determine the Continental Divide, which separates
the rivers that flow into the Pacific, from those that flow into the Gulf
of Mexico (an arm of the Atlantic Ocean.)
15. Testing Their Understanding: Use the Watershed Map of New York
State, and sketch the watershed of the Hudson River. Where does the
river start, and where is its mouth? Suppose a factory on the Mohawk
River dumps chemical wastes down their drainage pipes. How does
that effect you as a resident of New York City?
Extension Activity: Canals are built to connect one watershed to another.
For example, the Erie Canal connects the Great Lakes Watershed to the
Hudson River Watershed. Look at a profile of the canal. Students should
notice that it sometimes goes uphill and then downhill. How can this be?
What do locks have to do with this, and where must the water come from?
River Model
The “Die” Model
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