Google Earth and Meandering Rivers
Summary
This activity uses Google Earth to introduce students to a variety of measurements related to meandering rivers by looking at how rivers around the world have changed over time.
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Context
Audience
200-level undergraduate class on Earth Surface Processes. Required for majors and taken by many environmental studies students. Intro geology is the only pre-requisite. There is a page describing this class here.
Skills and concepts that students must have mastered
Reading or lecture on rivers. At this point students have read the rivers chapter from Key Concepts in Geomorphology and had a lecture on the same material. They have been introduced to rivers in planform and should know what sinuosity, wavelength, amplitude, and radius of curvature are. We have covered in class why these terms vary and what self-similar patterns there are among locations. Rivers come towards the end of my class, so students have already used Google Earth and have some context for dynamic processes shaping Earth's surface.
How the activity is situated in the course
This is an exercise that is part of a one-week unit on low-land rivers. It takes one 50-min class period.
Goals
Content/concepts goals for this activity
- Plan-form of meandering rivers and specific concepts associated with them (sinuosity, wavelength, amplitude, and radius of curvature).
- Making quantitative geomorphic measurements
- River migration over time.
Higher order thinking skills goals for this activity
- Interpretating aerial/satellite images.
- Using GIS-technologies to gain quantitative geomorphic information.
Other skills goals for this activity
- Using Google Earth
Description of the activity/assignment
This exercise takes advantage of student's interest in Google Earth to teach some basic concepts about meandering rivers. Students prepare for class by reading about lowland rivers and/or hearing a lecture on them. They bring their own laptops to class or share with a partner or I take the entire class to the computer lab next door. In class they work through the worksheet and use Google Earth to take quantitative measurements of the rivers. They look at historic migration of meander bends and quantify river sinuousity, wavelength, amplitude, and radius of curvature of meander bends. They explore meandering bedrock rivers in Taiwan as a cool thought exercise in how that can happen. They end with looking at images from an area that they will have a field trip to during their next lab period. To keep people from flying through the exercise and getting bored, we do the whole activity in think-pair-share style. Students work on a location, answer the questions, and then we discuss it as a class.
Determining whether students have met the goals
I don't have any summative assessment for this assignment but a lab exercise has them do these calculations as part of a field trip report. As a formative assessment, I both talk with individual students/groups while they are working on a location and have a class discussion about each location before moving on to the next site. One could collect and grade the handouts as summative assessment.
Some things to consider with formative assessments:
- Are students trying to understand the differences between locations or just getting through it as quickly as possible?
- Do they seem interested in understanding what we can learn from the landscape using historic photos or just inferring past river locations?
- Are they being systematic and careful with their measurements so that they are meaningful?
- Are they discussing what they are finding with students around them?
- Do they ask good questions that would expand their knowledge?
- If they describe what they found to the entire class, are they articulate? Can they concisely explain what they found? Can they ask questions that would extend their knowledge?
If you have the students turn in the handout, I think I would grade it as "great", "ok", and "poor" for each question rather than looking for exact numbers that are correct.
Teaching materials and tips
Activity Description/Assignment: Student handout for Meandering rivers in Google Earth assignment (Acrobat (PDF) 91kB Oct2 15)
KMZ File with place locations: KMZ file with locations for the activity (KMZ File 1kB Oct2 15)
Here are some teaching notes for this activity:
- I have done this activity in a computer lab and with students bringing laptops. Both work fine. You don't want more than ~2 students/computer. In addition, tablets don't work for measurements in Google Earth.
- I've posted a kmz file with place locations. Have students download this at the start of the exercise.
- Make sure students have a recent version of Google Earth installed so that they can see the historic images. I send a reminder email the night before if students will bring their own computers.
- To keep the class somewhat on the same page and encourage students to think more deeply about each location rather than rushing ahead, I have the entire class work on one section (one location, usually), then we discuss it as a class, and then move on to the next site. You could do it with an end of class wrap up instead, but I find that discussions go better if you do this along the way.
- My students have used Google Earth and made measurements numerous times before doing this activity. If you haven't done this in your class, you probably want to have them go through a brief tutorial on using Google Earth at the beginning of the exercise. Here is a help page on making measurements in Google Earth: https://support.google.com/earth/answer/148134?hl=en
- For students to answer the last question comparing different areas, I ask them to do some basic searching online about the geologic/climatic setting of each of the rivers and to look for dams upstream. I do this partly because it is more inquiry-based for them then and partly because it gives students who are a bit more advanced time to dig deeper rather than twiddling their thumbs.
- The bedrock meanders are explained in a fair amount of detail in Stark et al. (2010). The gist of the story is that they find that storminess (number of typhoons a year) drives bedrock meandering. The mechanism is that rivers undercut the outside of meander bends, which causes landslides, which increases meandering.
- Solution Set:
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Supporting references/URLs
Students need to have the most recent version of Google Earth so that they can view historic images.
A paper about bedrock meanders in Taiwan: Stark, C. P., et al. (2010). "The Climatic Signature of Incised River Meanders." Science 327(5972): 1497-1501.
The text I use for my class: Bierman and Montgomery, Key Concepts in Geomorphology.