What is the value of water?

A natural watershed is the area of land from ridge top to ridge top that collects water and drains into the nearest stream, river, lake or other body of water.

Gravity and topography are key to  the interaction between the natural water cycle and the natural watershed.

Students will understand how the interaction between the natural water cycle and the natural watershed depends on gravity and topography,  everywhere and all the time.  During their walk outside in the previous activity, students may have seen how gravity was the force that moved water downhill. The topography of the ground determines the path the water takes to get to its destination. These two components define the natural watershed. In other words, water is on the move ‘down’ following the path determined by the topography of the area.

We all live in a watershed !

Students share their initial definitions of a watershed. They will revisit this definition later so have them write the definition in their notes.

Watershed video. This video is 4 minutes in length and gives a very good explanation of a watershed.
Chesapeake Unscripted: What is a Watershed? (Chesapeake Bay Program on Vimeo.)
→At Timestamp: 3:27 the narrator gives the definition of a watershed.

Watershed Vocabulary and components Review.

In this activity students will build a model of a watershed to show how gravity and topography work together to move water.  This can be done as a demonstration,  in small groups or pairs.  It does require a small amount of water from a spray bottle.

Instructions are outlined in the Instructional slide deck and as a student ready step-by-step instructions.

Building a Model of a watershed:

Students will use foil, or paper, and markers to build a model of a watershed. As students build their watershed, have students identify the geographic elements in their model. Have them notice areas of elevation (hills) or depression (valleys); where natural paths may have been formed. All of these elements impact the watershed.

They will mark specific geographic areas on their model in black and blue marker to be able to see how the water impacts the land.

Have students hypothesize where water might collect (pool or run) during a rain storm and make sure those areas are highlighted in blue (see watershed model directions).

To model precipitation, use a spray bottle to gently mist the model with water.

After observing their watershed in action, students may want to revise their definitions of a watershed using the vocabulary of the water cycle. Focus students on how landform features impact the watershed. If the students are working individually or in small groups, take time to compare their different models and draw any conclusions.

Group discussion prompts:

• Where did the water flow when precipitation landed in the model?
• What did the black lines represent in this model?
• What did the blue lines represent in this model?
• What happened to the water that landed near the black lines?

Note to teachers: Now is a good time to make the point that watersheds are sometimes called drainage basins (much like how a sink works to drain water to the lowest point)

Have students write down their observations using the vocabulary of the phases of the water cycle to make the connection to the real world.

DEVELOP THE CONNECTION

Help students make the connection between the contour lines on a topographic map and water flow. A topographic map shows 3D elevation in two dimensions. Since we know that gravity makes water go down, the contours on the topographic map help us to predict how and where the water will flow and shows the highest point (or ridge line) of the watershed.

How to read a topographical map: (This is included in the student slide deck)

We are about to look at a map from 1894 of Roxborough. Here are some key things to know to help you ‘read’ the map:

• Contour Lines (Brown Lines): These connect points of the same height. If you walk along one line, you stay at the same elevation.
• The “Hills” Trick: Concentric circles (circles inside circles) are hills. The smallest circle is the peak.
• Steep vs. Flat:
  • Close lines = Steep! (Think: hard to climb).
  • Far apart lines = Flat/Gentle slope (Think: easy walking).
• V-Shapes (Valleys): V-shaped lines pointing toward higher ground show a valley or stream.
• Colors & Symbols:
  • Blue: Water (rivers, lakes).
  • Green: Forests or parks.
  • Black/Red: Roads and buildings (like schools or churches).
• Map Key (Legend): Always check the legend to understand what the specific symbols on that map mean.
• Compass Rose: Look for the arrow pointing North to orient yourself.

Roxborough Reservoir from 1894 topographic map. (have fun examining this historic map for other stories this map tells!)

We all live in a watershed !
Now that we have discovered that gravity and landforms (topography) play a major role in defining a watershed or drainage basins it’s time to discover that no matter where you live, play or go to school, you are in a watershed

Look at the topography of your school.

How to find your school on https://www.philageohistory.org/tiles/viewer/     

To view a topographical map of your school  visit:  https://www.philageohistory.org/tiles/viewer/

Enter your school address in the Find Address box on the top right menu.

Click GO

A map of your school with a lot of information will be displayed. To remove the informational layers,  UNCHECK  Modern Street Labels and any other map layers that are checked.

CHECK the box next to c. 1890-1910 Topo Maps

This will display a topographical map of your schoolyard.

Check out this resource to follow a drop of rain through a watershed!
River Runner is an interactive resource that lets users trace the path of a drop of rain, from where it first falls to the ground, to the body of water where it ends up. The resource utilizes data from the United States Geological Survey to map watersheds and get accurate topographies of mountains as well.

Discuss if there are any days that they experience a problem with water drainage in their schoolyard?

Talk to the building engineer to find out about problem areas on the schoolyard for flooding to start to get a sense of the impact?