Pop Bottle Hydrograph
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process.
This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Apr 30, 2008
Skills and concepts that students must have mastered
How the activity is situated in the course
Experiments take ~10 min to run and ~ 5 to discuss. Need 1-3 student volunteers.
Content/concepts goals for this activity
Reinforce basic skills: data collection, setting up a table, unit conversion, plotting data.
Terms: unsaturated zone characteristics, effect of impermeable surfaces and sewering, effect of vegetation, etc.
Higher order thinking skills goals for this activity
Transformation of data: measure weight over time but plot discharge. Analogous to stage-time graph conversion to hydrograph (but does not address rating curves).
Formulation of hypothesis: following basic model, have students discuss expectations for altered models before these are run.
Other skills goals for this activity
-Calculate a water balance to determine amount of transport vs. storage in the watershed if components are weighed before and after.
-Insert gutters (straws) that will make system more "flashy"
-Add sponge or vegetation to increase peak lag time and decrease rising limb (Admission: I haven't tried this!)
-Compare different materials (gravel vs. silt) and examine transmissivity (note, to save time, can be completed side-by-side tests to just compare time.)
-Just re-run first setup to examine effect of antecedent moisture (see caveat in challenges!)
Description of the activity/assignment
Determining whether students have met the goals
- Have students draw concept sketch (of sorts) that includes 2 hydrographs for different settings (urban vs. forest, upstream vs. downstream floods) with labels (lag time, rising limb, falling limb, peak discharge) and short descriptions that explain why the hydrographs are shaped as they drew them. Would be quick to grade but synthesizes lots of info.
- Would be good to develop questions that test misconceptions.
Download teaching materials and tips
- Activity Description/Assignment (Microsoft Word 97kB Jul16 08)
- Form for data collection and graph (Excel 31kB Apr30 08)