Building a Watershed Model

Transcription

1 9 Building a Watershed Model Purpose Students will build a model to identify the characteristics of a watershed. Students will learn how elevation determines the flow of water within a watershed. Overview In this activity, students will work in groups to create a landscape that includes multiple watersheds. Students will observe the relief of the landscape and form predictions about how water will move through the landscape. They will simulate rainfall using a spray bottle and observe how the water flows through the landscape. They will compare their predictions to their observations. Student Outcomes Activate student prior knowledge through reflection on experiences they have had with rain events, storms, and flooding events. Practice inquiry investigations and questioning skills by comparing predictions and observations. Identify characteristics of a watershed, patterns of water movement within a watershed, and how elevation influences water flow. Time minute class period Level Secondary earth/environmental science (9-12) Materials and Tools White plastic tablecloth Large, waterproof tray Newspaper or magazine pages Spray bottles filled with colored water - this represents rain Permanent markers Masking tape Prerequisites GLOBE Watersheds Human Impact Activity 1: Philadelphia Tackles Rainwater Runoff Pollution podcast Activity 2: Building a Watershed Model - Teacher Overview - 2 pages

2 10 Background Students should be familiar with the basic definition of a watershed. They should also be familiar enough with the water cycle to know that new water reaches the ground in the form of precipitation. Water that does not evaporate or get absorbed as ground water drains into a body of water as surface runoff. A variety of factors influence the amount of surface runoff that flows into a river, including topography and type of land cover present. Teaching Notes This activity can be done in groups or as a class, depending on available materials and class size. Once students have built their watersheds, but before they begin to use the spray bottles to create rain, engage them in the following questions: a. Discuss the definition of a watershed. (The areas of land that drain into a body of water river, lake or pond is known as a watershed.) b. What are the highest elevations and lowest elevations on your landscape? c. Where will water go if rain were to fall? d. Where will rivers and streams develop? As indicated in the student guide, students will then use markers to show where they predict water will flow and pool in their watershed. They will also record their predictions in the student guide. Activity 2: Building a Watershed Model - Teacher Overview - 2 pages

3 11 Name Date Class Introduction Building a Watershed Model Let s review the water cycle. We know that new water reaches the ground in the form of precipitation. Water that does not evaporate or get absorbed as ground water drains into a body of water as surface runoff. A variety of factors influence the amount of surface runoff that flows into a river. One major factor is the type of land cover found on the landscape. What other factors could affect surface runoff? In this activity you will predict how water flows into rivers and streams. You will be making a model of a landscape that includes multiple watersheds. You will use newspaper to form hills and valleys and a plastic tablecloth to represent the surface of the earth. After you write down your predictions about how you think the water will flow in your model, you ll use a spray bottle to simulate a rainstorm. The purpose of this model is to explore the factors that determine how rivers and streams are formed. Materials and Tools White plastic tablecloth Large, waterproof tray Newspaper or magazine pages Spray bottles filled with colored water - this represents rain Permanent markers Masking tape Procedure: 1. Create your landscape. Crumple pieces of newspaper and arrange them on the tray. Design your landscape so that the newspaper forms taller mounds around the outer edges of the tray, and the shorter mounds in the middle. Activity 2: Building a Watershed Model - Student Guide - 4 pages

4 12 2. Lay the white plastic tablecloth over the crumpled newspaper. Secure the tablecloth along perimeter by taping it to the tray. 3. On your model, use a marker to label the areas of high elevation with an H. Label the low elevation areas with an L. 4. Discuss the following questions with your classmates and teacher: a. What is the definition of a watershed? b. What are the highest elevations and lowest elevations on your landscape? c. Where will water go if rain were to fall? d. Where will rivers and streams develop? 5. Using a different color, draw on the tablecloth where you predict the rivers and streams will form. Use arrows to show which direction you predict the water will flow. Draw circles where you think the water will form puddles. 6. In the box labeled Prediction draw a bird s eye view of the model, using H and L to indicate the areas of high and low elevation. Each group member should draw his or her own map. 7. In this same space, draw where you predict water will flow in your model. Use arrows to show water flow and circles to show where you think the water will form puddles. Predictions 8. Obtain a spray bottle from your teacher. Holding it about 5 inches above the plastic tablecloth, spray for several minutes until you see a continuous flow of water in your model. This is your model run. Take turns running the model. Each group member should begin his or her turn by spraying the model in a different place on its surface. Activity 2: Building a Watershed Model - Student Guide - 4 pages

5 13 9. Draw another elevation map of your model in the box labeled Observations on the next page. Draw what you observed during the model runs. Use arrows to show where the water flowed and circles to show where puddles formed. Observations Questions: Q1. In your own words, define the term watershed. Q2. What do all watershed boundaries have in common? Q3. How can there be two watersheds right next to each other? Activity 2: Building a Watershed Model - Student Guide - 4 pages

6 14 Q4. Describe what you observe about the way water flowed over the surface of your model. What type of land cover do you think most closely matches this kind of surface? Explain your response. Q5. Did the arrows you drew in your predictions landscape align with where the water actually flowed? Q6. What is a model? What is the purpose of building models? Q7. In your model, what determines where the water flows? Q8. What changes to the land could be made to slow the flow of water into the rivers and streams? What changes to the land would increase flow into the river? Q9. Suppose this model were to represent farmland a different type of land cover. How would that change the way water flows across the surface? Activity 2: Building a Watershed Model - Student Guide - 4 pages

7 15 Name Date Class Building a Watershed Model Introduction Let s review the water cycle. We know that new water reaches the ground in the form of precipitation. Water that does not evaporate or get absorbed as ground water drains into a body of water as surface runoff. A variety of factors influence the amount of surface runoff that flows into a river. One major factor is the type of land cover found on the landscape. What other factors could affect surface runoff? In this activity you will predict how water flows into rivers and streams. You will be making a model of a landscape that includes multiple watersheds. You will use newspaper to form hills and valleys and a plastic tablecloth to represent the surface of the earth. After you write down your predictions about how you think the water will flow in your model, you ll use a spray bottle to simulate a rainstorm. The purpose of this model is to explore the factors that determine how rivers and streams are formed. Materials and Tools White plastic tablecloth Large, waterproof tray Newspaper or magazine pages Spray bottles filled with colored water - this represents rain Permanent markers Masking tape Procedure: 1. Create your landscape. Crumple pieces of newspaper and arrange them on the tray. Design your landscape so that the newspaper forms taller mounds around the outer edges of the tray, and the shorter mounds in the middle. Activity 2: Building a Watershed Model - Answer Key - 4 pages

8 16 2. Lay the white plastic tablecloth over the crumpled newspaper. Secure the tablecloth along perimeter by taping it to the tray. 3. On your model, use a marker to label the areas of high elevation with an H. Label the low elevation areas with an L. 4. Discuss the following questions with your classmates and teacher: a. What is the definition of a watershed? b. What are the highest elevations and lowest elevations on your landscape? c. Where will water go if rain were to fall? d. Where will rivers and streams develop? 5. Using a different color, draw on the tablecloth where you predict the rivers and streams will form. Use arrows to show which direction you predict the water will flow. Draw circles where you think the water will form puddles. 6. In the box labeled Prediction draw a bird s eye view of the model, using H and L to indicate the areas of high and low elevation. Each group member should draw his or her own map. 7. In this same space, draw where you predict water will flow in your model. Use arrows to show water flow and circles to show where you think the water will form puddles. Predictions 8. Obtain a spray bottle from your teacher. Holding it about 5 inches above the plastic tablecloth, spray for several minutes until you see a continuous flow of water in your model. This is your model run. Take turns running the model. Each group member should start his or her turn spraying the model in a different place on its surface. Activity 2: Building a Watershed Model - Answer Key - 4 pages

9 17 9. Draw another elevation map of your model in the box labeled Observations on the next page. Draw what you observed. Use arrows to show where the water flowed and circles to show where puddles formed. Observations Questions: Q1. In your own words, define the term watershed. The area of land that drains into a body of water river, lake or pond is known as a watershed. Watersheds are outlined by ridges of high elevations, or divides. Q2. What do all watershed boundaries have in common? They are always located at the top of hills and mountains and encircle the water body. Q3. How can there be two watersheds right next to each other? A ridge separates the two areas. Q4. Describe what you observe about the way water flowed over the surface of your model. What type of land cover do you think most closely matches this kind of surface? Explain your response. The water flowed over the surface, none of it seeped in. Small streams flowed into each other to form larger streams, and the water collected in low- lying areas. This matches the kind of runoff described in the podcast so this model represents developed land. Activity 2: Building a Watershed Model - Answer Key - 4 pages

10 18 Q5. Did the arrows you drew in your predictions landscape align with where the water actually flowed? Student answers will vary. Q6. What is a model? What is the purpose of building models? A model is a simplified representation of a real- world system or phenomenon. People build and manipulate models to so they can better understand how these systems work. Q7. In your model, what determines where the water flows? Students should observe that the water always flows downhill. Topography determines the path of water in this model. Q8. What changes to the land could be made to slow the flow of water into the rivers and streams? What changes to the land would increase flow into the river? Decreasing the height of the high elevations flattening the landscape would slow the flow of water over the model. Creating more high- elevation spots on the landscape more places with a steep slope would increase the rate of flow. Students might also refer to changes in land cover that would change rates of water flow. Q9. Suppose this model were to represent farmland a different type of land cover. How do you think that would that change the way water flows across the surface? Water would flow more slowly over farmland than developed land because it would encounter more surface friction from planted crops than it does over the simulated paved surface. Water could also infiltrate the soil, which would reduce surface runoff and lead to decreased puddling (potential flooding) in low- lying areas. Activity 2: Building a Watershed Model - Answer Key - 4 pages