Watershed Mapping From A Road Map
 

Concepts:

  • Water flows downhill; the area around connecting streams that drain to a central water body is a watershed.
  • A stream or river reach near a school has its own watershed.
  • Every river has its own characteristics, but all have a "tree-like" branching pattern.
  • Downstream areas are impacted by changes or activities occurring upstream.

    • Objectives:

  • To determine drainage pattern of the river.
  • To establish mental images of the watershed for use in later discussions about wildlife, habitat, land uses, and water quality.

    • Materials:

    A county road map (or state or regional map if the watershed falls in several jurisdictions) showing streams and rivers. Pencils and crayons. Optional: topographic map.

    Subjects:

    Social Sciences

     

    Preparation and Procedure:

    1. Discuss where surface water comes from (rain, snow melt, springs), and that it always seeks a downward course, and rivers journey toward the sea. (You might also discuss the appearance of other drainage and/or branching patterns, such as: veins in the human body or in leaves, tree branches, lightening strikes, computer programs, etc.)
    2. Explore with students what they already know about the stream or river near the school (direction of flow, headwater area, outlet, length, towns through which it flows).
    3. Students locate the school on the road map, and the closest stream or river near the school.
    4. Students follow (upstream and downstream) the stream segment near the school, including in their search all streams that are connected. Students place a pencil dot at the headstream end of every stream connected in their watershed.
    5. Students connect the dots by pencil. (This is a close approximation your watershed outline.)
    6. Students refine this outline by either assessing equal area to neighboring watersheds' stream ends, or by adjusting their watershed line to elevation points marked on the road map or to elevations on a topographic map.
    7. Draw the refined watershed boundary with a colored crayon.
    8. Draw watershed boundaries in different crayon colors around all major tributaries in the watershed.
    9. Color or otherwise mark areas of the watershed that represent large areas of forests, farms, industry, and towns or settlements. Discuss the likely impacts of land uses to areas of the river.

      Illustration of Watershed Map

     

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