Identifying Watersheds with Topographic Maps

Goals for the Lesson

• Students will work cooperatively to complete various components of the lesson.
• Students will identify the features of a watershed.
• Students will identify how topographic features create and comprise a watershed.

State Standards Addressed: E & E Standards: Watersheds and Wetlands (4.1); Ecosystems and Their Interactions (4.6); Humans and the Environment (4.8)

Subjects Covered: earth science, geography, ecology

Topics: watersheds and topographic maps

Teaching Model: Focus-Explore-Reflect-Apply Learning Cycle

Materials Needed

• laminated topographic maps of local area; topographic maps can be ordered from the U.S. Geological Survey
• dry-erase markers
• aluminum foil
• crumpled newspapers
• plastic cups
• droppers
• paper towels

Preparation

Secure maps from available resource. Have maps laminated. Have all materials on hand and ready. Prompt students by having them recall what they learned from previous lessons related to the water cycle and topographic maps.

Introductory Activity (outside the classroom)

(adapted from Incredible Water w/ the Water Lion)

1. Divide class into groups of three or four students/group.
2. Each group is given a large piece of aluminum foil.
3. Each group is to create a watershed by placing the foil over crumpled up newspapers to create a simulated landscape with mountains, valleys, and a lowland area. All parts of the foil should drain into the single low area. The outer edges should be turned upward to keep the water on the surface of the foil.
4. Fill a plastic cup halfway with water and mark the water level on the outside of the cup with a marker.
5. Each group is to then put the half-cup of water into a spray bottle and use the sprayer to make it "rain" on the watershed. Be sure to spray all of the water.
6. Observe how the water moves in the watershed. Catch all the runoff water in the cup at the low area. Note how much water moved through the watershed. Was some water retained in/on the watershed? What do these bodies of water represent?
7. Remove all the water from the watershed, using a medicine dropper if necessary, and place all the water back in the cup. When you have removed as much water as possible, make a mark on the cup to indicate the new water level.
8. Now, put pieces of paper towel on the high parts of the model watershed. They will imitate the effect of the ground storing some of the water.
9. Again use the spray bottles to make it "rain" on the watersheds. Observe.
10. Again, return as much standing water as possible to the cup. Compare the water levels. What does this tell you about ground water?
11. Ask students to explain how what was just demonstrated represents the water cycle.

Follow-up Activity

1. Divide class into three groups (appx. six students per group).
2. Each group is given a topographic map of the local area of the county in which the school is located.
3. Ask the students to identify/describe what they are looking at.
4. See if anyone can locate our specific location on the maps.
5. After ascertaining the extent of the class's knowledge, ask the students to recall the concept of a topographic map (how it is a two-dimensional representation of the three dimensions of the surface of the land).
6. Referring to the topographic maps, have each group identify the following:
   • a mountain top
   • a mountain ridge
   • a steep mountain slope
   • a gentle slope
   • a stream
   • the confluence of two streams
   • a field or lowland area
   • cities or towns
7. Have the groups focus in on the specific section of the map that represents the location of the school. Have them locate the stream that flows by the school's property. Trace the stream upstream to determine it's origin and also downstream to where it meets up with a larger stream.
8. Challenge the groups to mark the surrounding area that delineates the stream's watershed. Have them mark the laminated maps with dry erase markers to indicate the watershed boundaries.
9. Have the groups share their mappings.
10. Ask for someone to explain the connection between the two activities (the activity involving the foil models of a water shed and the activity of analyzing the topographic maps).

Assessment

During the next school day, arrange class time so students can be dealt with individually to assess their knowledge and understanding of topographic maps and watersheds. Present each student in turn with a topographic map different from the one they studied the previous day. Use a map of the entire county or one representing a similar but different local area. Have each student identify each of the eight items asked for in step 6 of the map activity as well as having the student mark a watershed area with a dry erase marker.

Extension

1. Arrange a visit to a private home located along Pine Creek where the homeowner has an entire wall of his mudroom covered with topographic maps that cover parts of six counties of north-central PA. Students can locate the site of the school and explore the watersheds throughout the area that leads into the Susquehanna River. Use this activity as a springboard into a lesson on stream analysis; analyzing the stream close to its source and then at a point after it has passed by farmed land and urbanized land area.
2. Have students identify on the map where the stream by the school facility leads into a wetland area just prior to where the stream leads into a larger stream. Use this as a springboard to a discussion of or lessons on wetlands. On a future class day arrange for a field lesson when students will travel along the stream to the wetland area where they can explore and identify the various components of the wetland.

References

Incredible Water with the Water Lion (2002). University Park, Pa.: The Pennsylvania State University.

Yoas Services, 509 W 4th St., Williamsport, PA. Phone: 570-326-2041 (vendor of topographic maps)

Swistock, Bryan, and Sanford S. Smith (2001). From the Woods: Watersheds. University Park, Pa.: The Pennsylvania State University.

Topographic maps can also be ordered from the U.S. Geological Survey

Author

George Ness, BLaST IU17; LaSaQuik Alternative Education Program