Study of the Horsepen Creek Stream System
Angela M. Moore, Marlene McCauley, David Dobson (Guilford College)
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This is an in depth laboratory exercise that can be adapted to any stream system, and has been successfully implemented with classes composed primarily of non-majors. This field exercise allows students to go through the entire process of forming hypotheses, collecting data, and analyzing/presenting their work in a professional format.
Undergraduate introductory course in geology
Skills and concepts that students must have mastered
Students should have been introduced to the concepts of the hydrologic cycle, stream discharge, and of sediment transport. The details of water quality and chemistry are included in the lab, but at a very basic level that is discussed in the handout itself. It is important to emphasize how stream systems are directly related to the students, in our case Horsepen Creek has been identified as an impaired stream by the EPA, and our small campus stream is a tributary to Horsepen Creek. Horsepen Creek flows into one of the small reservoirs used by the City of Greensboro as a drinking water supply, a critical issue in the recent severe droughts we've experienced in North Carolina.
How the activity is situated in the course
This is a stand alone exercise but is the most significant, integrative assignment students undertake in the course. It is structured as three laboratory periods; one to collect the data, and another lab period to learn to use spreadsheets to graph and analyze the data, and another lab focused on individual assistance with the writing and format of the final report.
Content/concepts goals for this activity
Students learn a variety of skills in this exercise, including the delineation and investigation of watersheds, the measurement and calculation of stream discharge, and performing basic sediment size sampling and water quality sampling.
Higher order thinking skills goals for this activity
Students must analyze specific data and determine if the results are "as expected" based upon the lectures and reading. Specific factors that are assessed include water quality parameters, sediment size distributions, and stream discharge and velocity. In addition, students must also develop a hypothesis of their own that can be tested with the collected data, and they are expected to incorporate data from previous years in this analysis.
Other skills goals for this activity
Students learn to methodically perform field data collection, including the use of water quality meters, sieving and weighing sediment samples, and measuring stream velocities and cross-sectional areas. Another goal of this assignment is to introduce students to professional, technical writing in the sciences.
Description of the activity/assignment
To prepare for this lab activity, there are several preceding lectures on the basics of the hydrologic cycle, river systems, and sediment transport. We also introduce the watershed, including city maps of the land use in the area of the creek. Students read the relevant chapter in the textbook beforehand. Students collect the field data from the stream during the first week, and the second week focuses on teaching them to analyze the data, and to use spreadsheets to graph their results. A very detailed, formal report is handed in by each student at the culmination of the project.
The field experience requires students to collect and analyze data from four different stations along a local, impacted creek system. At each location students measure velocity and cross-sectional area, which they use to calculate the stream discharge. Students also collect data on the sediments by sieving and weighing samples, which they later use to generate cumulative sediment distribution curves. Water quality collected at each site includes total coliform, turbidity, nitrate concentrations, pH, dissolved oxygen, and temperature. Students are required to discuss all of these factors in their final report, and to assess whether the data are 'as expected' from the lectures and the reading. In addition, students develop and test their own hypothesis about the system. For example, they might choose to investigate whether sites with higher flow velocities correlate with higher sediment sizes.
This activity reinforces specific concepts about streamflow and sediment transport, and also illustrates how the field of geology contributes to our understanding of the interaction of humans and their environment.
Determining whether students have met the goals
Students are required to turn in a formal, comprehensive laboratory report that is used to assess their understanding of the field and lab work. A grading checksheet has been developed that is given to the students, to help organize the paper and to give students a clear outline of all the pieces that must be included.
More information about assessment tools and techniques.
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