Department of Earth Science | Northeastern Illinois University

Earth Science 121

Watersheds and Hydrographs: Finding and Analyzing Patterns
(Due at the beginning of class, Wednesday, April 25, 2007)

Where to Begin

In class, you collected data on stream hydrographs (graphs of discharge vs. time) and some information on watersheds, and we recorded it all on a worksheet.  Click here if you want a clean copy of the legal-sized data collection sheet we used in class (Excel worksheet).

If you need to look at the hydrographs again, they're hanging in the classroom, along with the Illinois maps.

Now, your job is to analyze the data to find patterns.  Because the data we are working with are "live" and have never before been collected in the same place at the same time, you could discover something entirely new!  So look hard.

What to Do with the Data

Once you have a complete data set, do the following:

1) 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, say, urban areas, their hydrographs seem to exhibit a certain characteristic, something that doesn't occur when they are in rural areas.  Or maybe you'll find that when the storms occur in a certain season, or in a certain type of terrain, the hydrographs look a certain way.  For something to be a pattern, it has to show the same relationship repeatedly. 

List as many patterns as you can find!  The person who lists the most patterns will get a (small) prize.

2) Choose two of the patterns you listed in Step 1, and for each one of the two patterns, do the following:
       A) Propose a hypothesis to explain the pattern.  (For example,  why does variable Y seem to increase every time variable X increases?  Explain.)

B) Note any exceptions to the pattern, and explain them.  (Why do these streams/hydrographs not fit the pattern?  What's different about them?)

       C) Suggest a way you could further explore your hypothesis, or a way to test it to see if it holds true.

What to Hand In

* Your data collection worksheet (see the link above if you want a clean copy with the corrections added.)

* Your typed answers to Questions 1 and 2, above.  Remember to answer Question 2 for two of the patterns you discovered!

Department of Earth Science | Northeastern Illinois University

© 2007 Laura L. Sanders.  Last updated April 18, 2007.