Rivers: Short In-class Activity
This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.
Images of the James River at Belle Island, Virginia, including one at flood stage, a plot of peak streamflow since 1935, and an image of potholes in the Petersburg Granite at the same location. These images can be used to have the students make observations, estimates, and interpretations.
These images linked to the thumbnails below give students opportunities to observe geologic features, consider changes in river discharge and their consequences, and learn about flood frequency by having them
- make observations
- do estimations and calculations
- present interpretations based on their observations and on their prior knowledge
- pose questions for further information
Context for Use
These images can be used in both small and large entry-level geoscience courses in various think-pair-share formats, with times ranging from five to fifteen minutes and could be used for a follow-on activity.
Description and Teaching Materials
James River in Richmond, Virginia at flood stage, looking upriver from the Robert E. Lee bridge (thumbnail linked to image). Belle Isle is on the right, November 1985. Photo by Rick Berquist, used with permission.
- What is happening in this picture?
- What makes the water so brown?
James River in Richmond, Virginia (thumbnail linked to image). The Robert E. Lee bridge and the bridge in the previous photo are in the background. Photo by Heather Macdonald.
- Estimate the height of the river during the flood shown in the previous image
Streamflow data for the James River, near Richmond, Virginia (thumbnail linked to image). Diagram generated by the USGS Peak Streamflow resource for the James River stream gage near Richmond, Virginia.
- Annual data are provided by the website above and can be downloaded as a graph or in a spreadsheet-ready format for students to use.
Potholes along the James River at Belle Isle, the same location as previous images (thumbnail linked to image). Photo by Heather Macdonald.
- Describe the shape of the bedrock river channel.
- How were those holes formed?
Teaching Notes and Tips
One approach for using these images would be to have students discuss an image or images with their neighbor, asking them to make observations and then consider what their observations mean. You might ask students to estimate the river stage (height). You could also ask students to list questions they would want answered to be able to make better interpretation or estimates.
After a few minutes, call for responses from students. You might do this using a using a think-pair-share format. Be prepared for a range of responses for estimates of flood stage (river height).
You might use these images in a discussion of flood frequency and magnitude and what is meant by the terms 50-year flood, 100-year flood. The U.S. Geological Survey "Surface Water Data for the Nation" website (more info) includes historical and real-time streamflow data. Stream flow data from the stream gage of the James River near Richmond, Virginia is available in a variety of formats including table, graph, and spreadsheet-ready.
From 1935 to present, the 1985 flood is the flood with the third highest magnitude. Note that in the plot of peak stream flow per year, water year does not always correspond to calendar year and the November flood occurred in the 1986 water year. The three highest peak stream flows since 1935 are
- June 23, 1972, 28.62 ft (gage height), 313,000 cfs (discharge)
- August 21, 1969, 24.95 ft (gage height), 222,000 cfs (discharge)
- November 7, 1985, 24.77 ft (gage height), 218,000 cfs (discharge)
The potential questions given below with the images are examples of questions to use as follow-up questions after students give their initial responses or could be a series of directed questions if you don't use a think-pair-share structure.
This activity includes informal assessment of the class. You could also collect the estimates and/or lists of observations and interpretations.
References and Resources
Sources for images:
- The American Geological Institute maintains a growing Image Bank (more info) , divided by category.
- Earth Science Picture of the Day (more info) has a searchable archive of photos.
- Martin Miller, a geology professor at the University of Oregon, has posted an online slide collection (more info)
- Lou Maher, a geology professor at the University of Wisconsin, has collected aerial views in his Geology by Lightplane (more info) project