Department
of Earth Science |
Northeastern
Illinois University
INTRODUCTION TO EARTH SCIENCE
ESCI 121
Section 05
Fall 2008
Department
of Earth Science |Northeastern
Illinois University
| ACTIVITY ONE |
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On the Galena, Illinois quadrangle, find the word “RAWLINS” in the middle of the map. Between the W and the L in RAWLINS flows an intermittent stream. Using tracing paper, outline the watershed (drainage basin) for this stream. To do this, you may wish to follow this strategy:
1) Place the tracing paper over the stream area and mark on the paper a few landmarks that appear on the map. When the paper slides around, you’ll be able to re-orient it using these landmarks.
2) Using blue pencil, trace the course of several streams that occur in the area, including the one we are working on.
3) Find the highest land between the streams and our stream of interest. Draw a very light line following the general location of this high area.
4) Now, get more precise: Locate the very highest places between the streams. Ask yourself, “If rain fell to the land surface here and started flowing downhill, which way would it flow?” If it goes in a direction that makes it end up in our stream of interest, it is part of that watershed! Draw the exact line showing the boundary of the watershed. |
| ACTIVITY TWO |
| Sketch a topographic map of the area carved in the sand on the stream table. When you are done, have the instructor check your map. |
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ACTIVITY THREE |
Using the topographic quadrangles of Chicago Loop and Palos Park, find a place that illustrates the following features. Label and place sticky notes on the map to indicate the location of each feature. | |
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* a steep slope * a closed depression * a round hill top * a ridge (elongated hilltop) * a lake * a benchmark |
* a stream; find two places where contour lines cross the same
stream and put sticky notes on the map to show both places. Tell what
direction the stream is flowing. * a “Gaging Station” along a stream * a forested or undeveloped area (how can you tell?) * an urban area (how can you tell?) |
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| ACTIVITY ONE: The Stream
Table
Experiment A: Turn the water on by flipping the switch. Adjust the discharge by turning the valve until there is a small but continuous flow. This flow will create a stream. Carefully observe the stream for the next 5-10 minutes. It will change continuously during that time, and your job is to observe what happens. w How does the stream channel form? What shape does it take? Does the shape change over time? w Where does erosion occur? Where does deposition occur? Does this change over time? If so, how? w What feature forms where the stream meets the ocean? Sketch it. Place a toothpick near the main channel in this area. Watch it for a few minutes. What happens? If you build your house on a feature like this, what is likely to happen to it?
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| ACTIVITY TWO: Graphing Your Discharge Data w Graph the stream data you collected in preparation for an exercise next time: graph discharge vs. time, showing the 10 days before the peak flow, the day of the peak flow, and the 10 days following the peak flow. Follow the example shown in class. w Write the name of the stream and gage on a sticky note and apply it to the map of Illinois to indicate the location. |
(Skip Activity Three)
| ACTIVITY FOUR:
Present your stream data. Tape your
graphed discharge data to a sheet of poster paper.
In LARGE letters that can be read from halfway
across the room, show the following information: w Stream Name w Gage location (name of town) w Dates for which discharge is graphed w Peak flow (in cubic feet per second) w Drainage area w Your name |
| ACTIVITY FIVE: Collect and analyze the class'
collective data. w Use the data collection sheet provided (a clean copy can be printed from the Excel worksheet (legal size paper works best) linked here). w Fill in the data collection sheet by examining the posters around the room. Once your data collection sheet is complete, sit with a group of 2-3 other students and do the following: A) Analyze the data, looking for patterns in the relationships between variables. Look for trends: for example, you might find that whenever variable X increases, so does variable Y. Or, when watersheds are located in a certain kind of area, their graphs seem to exhibit a certain characteristic. Or maybe you'll find that when the storms occur in a certain season, or in a certain type of terrain, the graphs have a certain shape or look to them. For something to be a pattern, it has to show the same relationship repeatedly! B) Choose two of the patterns you listed in Step 1, and for each one of the two patterns, do the following: i) Propose a hypothesis to explain the pattern. (For example, why does variable Y seem to increase every time variable X increases? Explain.) ii) Note any exceptions to the pattern, and explain them. (Why do these streams/graphs not fit the pattern? What's different about them?) |