Big Idea
How the land and water interact with the natural water cycle is a key idea to understanding the answer to the question “What is a Watershed?”
Driving Question
- What is the value of water?
Guiding Question
- What is a watershed?
- How does the natural water cycle depend on gravity and topography everywhere and all the time?
Summary
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.
Instructional Plan
Engage
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.
Explore/Explain
In this activity students will build a model of a watershed to show how gravity and topography work together to move water. They will also see in their different models, that as Earth’s features define the watershed, the topography and geography may change, the forces of moving water down the watershed stay consistent.
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?
Elaborate
Return to your schoolyard map. Analyze where puddles collect and how rainwater moves through the schoolyard. Can they hypothesize about the change in the topography of those areas? Do they see areas on the schoolyard that are higher than others? What forces are at work to move the water “down” to follow the curves of the land?
How might they note that on the map?
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. This website will show students how a drop of water would travel from the schoolyard through to the river. A demonstration that We ALL Live in a Watershed!!!
Extension
Look at a topographical map of your school that shows natural landforms before your the built environment was transformed (paved over and built up) .
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.
A legend for reading a topographical map is included in the slide deck on slide 8.
Teacher Support
Driving Question
- What is the value of water?
Guiding Question
- What is a watershed?
- How does the natural water cycle depend on gravity and topography everywhere and all the time?
Students will:
- Describe how gravity and topography interact to move water through a watershed.
- Earth’s features may vary geographically, but the forces of gravity and topography define the watershed.
Watershed (noun) The region or area of land that drains into the nearest river or stream or other body of water.
Contour Line (noun) A line on a map joining points of equal height above or below sea level.
Gravity (noun) The force that attracts a body toward the center of the earth, or toward any other physical body having mass.
Groundwater (noun) Water held underground in the soil or in pores and crevices in rock.
Surface Water (noun) Water that collects on the surface of the ground.
Topography (noun) The study of elevation, or the peaks and valleys of a landscape, and how they affect the flow of water
Tributary (noun) A river or stream flowing into a larger river or lake.
Analysis of the features of their watershed model.
Applying new knowledge of topography to topographical map of school. (Extension)