Data Puzzle

To pic : Watersheds

Student Pages

Where did the water go?

Stream Monitoring Station on Cascade Brook

L

ocal research scientists installed a stream monitoring station on Cascade Brook in order to better understand how water moves through this small watershed. The downstream community depends on the water from this watershed and has been monitoring rainfall in the watershed for several years. Now that there is a stream monitoring station installed, the community wants to see if the rainfall Source: Courtesy of Martin Stute. numbers match the stream flow numbers at the monitoring station. If too little of the rainfall water is flowing through the station, there is a concern that water supplies might run short. Let’s find out. Directions: Follow steps 1 through 9. Use additional sheets of paper as needed and answer in complete sentences. 1.

Orient yourself to the topographic map (Figure 5.1, p. 124). 1a. Label the stream “Cascade Brook.” 1b. In what state is Cascade Brook located? 1c. Draw an arrow on the map to mark the direction in which the stream is flowing. In what compass direction is the stream flowing? 1d. Find the stream monitoring station. Label the boundary of the watershed that feeds into the stream monitoring station.

EARTH SCIENCE PUZZLES:

MAKING MEANING FROM DATA

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Data Puzzle

Watersheds

Student Pages Figure 5.1

Topographic Map of Cascade Brook and Surrounding Landscape (to be completed by student)

Cascade Brook stream monitoring station

s

Source: Adapted from U.S. Geological Survey topographic maps for Cornwall-on-Hudson and West Point, NY. Courtesy of USGS.

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Data Puzzle

Watersheds

Student Pages 2.

Notice that there is a grid superimposed on the map. Each square in this grid represents 100 m by 100 m in the real world. Using the grid, estimate the area of the watershed that feeds into the stream monitoring station. Include each square that is more than 50% inside the watershed. Show your work, and include units in your answer.

3.

You have just calculated the area of the watershed feeding into the stream monitoring station. Now we want to calculate the volume of water falling within this area (see Figure 5.2). This region received 114 cm of precipitation in a given year. In other words, if the year’s worth of precipitation were to be spread evenly across the landscape, it would form a layer 114 cm deep. What was the volume of water that fell into the watershed during this year? Show your work, and include units in your answer.

Figure 5.2

Volume of Precipitation Falling on a Watershed

Source: Illustration by Linda Pistolesi.

4.

Make a prediction. You have calculated the volume of water that fell in the watershed. What do you think was the volume of water that flowed through the stream monitoring station during this same year? Write your prediction down on a separate piece of paper, fold it over, and do not open it again until you have completed the puzzle.

EARTH SCIENCE PUZZLES:

MAKING MEANING FROM DATA

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Data Puzzle

Watersheds

Student Pages

Check with your teacher before going on. Your teacher might collect the predictions for a class discussion. 5.

6.

7.

8.

9.

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Table 5.1 shows the volume of water that passed through the Cascade Brook stream monitoring station each month for one year. Suggest some reasons (hypotheses) why the volume of stream flow varies so much from month to month. Clue: Think about the climate of this region of the country. What is the total volume of water that flowed through Cascade Brook at the stream monitoring station over the entire year? Show your work, and include units in your answer. Compare the measured volume of water flowing through the stream station in one year (see step 6) with your prediction of the volume of water flowing through the stream station (see step 4). Are they similar or different? Now let’s look at this quantitatively. Compare the total volume of water flowing through the stream monitoring station over the year with the volume of water falling in the watershed as precipitation during that same time. Express your findings as a percentage in a complete sentence.

Table 5.1

Volume of Water Passing Through Stream Monitoring Station, Jan.– Dec.

Month

Water Passing Through Stream Monitoring Station (cubic meters)

Jan.

99,094

Feb.

70,992

Mar.

81,842

Apr.

115,930

May

146,614

June

84,127

July

262

Aug.

0

Sept.

0

Oct.

76,429

Nov.

163,473

Dec.

130,619

Source: Courtesy of Black Rock Forest.

Suggest some reasons (hypotheses) why these amounts are not the same. Be prepared to defend your favorite hypothesis in class discussion.

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