Mapping: Map a Watershed Using Topographic Maps Copy

Teacher Goals

• Students will be able to read a topographic map.

• Students will develop a map of a watershed using a topographic map.

Required Resources

• Topographic maps 

  Free topographic maps can be obtained at The TopoZone, which is produced by Maps a la carte, Inc. Fill in the search boxes at the bottom of the web page.

  • Topographic maps
• No Description Available

  • Topo Diagram.jpg
  • Topographic maps
  • Watershed - Topographic Map
  • Watershed Map: Performance Checklist/Assessment

Steps

1. Know the "rules"

   1. Contours always occur in pairs. If you cross a 50 ft. contour moving uphill, you must cross another 50 ft. contour moving downhill.
   2. Contours never cross.
   3. Contours have equal vertical seperation. The vertical measure that is indicated between two contour lines is the same for any two lines on a map.
   4. All contour lines close on themselves. All contour lines will close someplace on earth.
   5. Contour lines do not merge or split. The lines must be continuous and close on themselves.
   6. The steepest slope is perpendicular to the contour. Streams always flow along the steepest slope and always cross contour lines perpendicularly. Refer to the diagram below.

   • Topo Diagram.jpg

2. Downstream outlet

   Locate and mark the downstream outlet of the watershed, this is the farthest downstream point in which you are interested.

3. Water features

   Locate all the water features such as streams, wetlands, lakes and reservoirs that eventually flow into the outlet. To determine whether a stream is flowing to or from a lake or river, compare the elevation of the land features to that of the water body. A lake will occupy only one elevation. If a stream crosses a contour or elevation line higher that the lake, then the stream is flowing toward the lake.

4. Mark directions

   Use arrows to mark the direction of the stream flow.

5. Mark the high points

   Find and mark the high points on the map. Then connect these points, following ridges and crossing slopes at right angles to contour lines. This line marks the watershed boundaries.

Teacher Notes

• Duration: One to two class periods.