Evaluation of watershed land-use changes and hydrologic impacts
This activity was selected for the On the Cutting Edge Reviewed Teaching Collection
This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are
- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Apr 3, 2007
Skills and concepts that students must have mastered
How the activity is situated in the course
Content/concepts goals for this activity
1. Better understand the relationship between land use and runoff or infiltration.
2. Develop and strengthen analytical and mathematical skills by quantifying volumes based on precipitation depths.
3. Recognize and compare differences in discharges over different time periods.
4. Provide experience in making empirical calculations that lay the foundation for eventual field data collection.
Higher order thinking skills goals for this activity
1. Understand sources of uncertainty in quantifying hydrologic processes.
2. Evaluate the relative size of those uncertainties and effects on results.
Other skills goals for this activity
Description of the activity/assignment
For each of the sets of documentation: historical and modern, the students follow the USDA-NRCS TR55 empirical procedure to estimate event runoff depths and peak estimated discharge from the watershed. An area-weighted curve number (CN) is calculated based on tabulated categories of land use. Some judgment is involved in adapting the tabulated land use categories to the specific watershed used, and selecting an appropriate statistical average rainfall event to use. The sum of Darcy's Law calculations of discharge along streamtubes to a surface stream or estuary provides a groundwater discharge value over time for comparison. Each of these parts of the activity provides opportunities for the instructor to discuss uncertainties and sources of error.
Note that although software allowing TR-55 analysis exists, it is simpler and more instructive to have students use the paper method and forms in the manual.
Determining whether students have met the goals
1. Results and analysis in lab reports that correspond to these exercises. There is no "right answer," but all students' calculations should be similar. It is instructive to compare all results as a class to illustrate uncertainty in the calculations and method as a whole.
2. Ability of students, as evaluated during class exams, to recognize what controls infiltration and runoff in a watershed.
3. Ease with which students can recognize the significance of order-of-magnitude calculations and understand the usefulness but inherent limits of such analysis for future lab exercises.
Download teaching materials and tips
Historical USGS Maps for New England and NY from the UNH Library:
United States Digital Map Library (Rootsweb.com)
United States Geological Survey EarthExplorer