This activity is part of the On the Cutting Edge Exemplary Teaching Activities collection (view details)

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Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as "Exemplary" in at least three of the five categories. The five categories included in the peer review 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 https://serc.carleton.edu/teachearth/activity_review.html.

Initial Publication Date: October 23, 2017 | Reviewed: March 13, 2019 (see revision history: 2 events)

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Educator Guide Lab 4: Sharing a River: The Colorado River Story

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Summary and Learning Objectives

In Lab 4, students take a journey to the Colorado River Basin near Lees Ferry. They explore aspects of the Colorado River Basin using a variety of resources, interactive maps, and tools such as Google Maps. This journey give them perspective on the scope of the watershed and how various stakeholders have siphoned the water from the river to serve seven western states' needs. Then they collect data concerning where the water comes from, who is using the water and how much they are using, and what the future may hold for the people living in the basin. In the final part of the lab, students use a quantitative method to measure the rings (using ImageJ) to produce a graph, a tree-ring chronology and use it to determine how water levels in the Colorado River Basin have varied over the past 200 years. They use the similar procedure followed by dendrochronologists to build a record that can be used to identify climate anomalies such as droughts. Then they compare their tree-ring width graph to published stream-flow data to determine how reliable a proxy tree rings are for measuring changes in the flow volume of the Colorado River.

Note: Please download the Student Activity Sheet (pdf or Word version) found in the Printable Materials section of this document if you wish to have students respond to Stop and Think questions as they go through the lab.

Learning Objectives

After completing this lab, students will be able to:

describe how tree rings can be used to determine past stream flow and hydrological conditions in the Colorado River Basin.
explain how proxy data, such as measurements of annual growth rings in trees, reveal the nature, scale, and duration of past climate events like droughts.
explain how tree-ring data can leads to a deeper understanding of the challenges we face as a society and to helps to guide our decision making.

Activity Overview and Teaching Materials

Detailed overview of what students will do in each part of the lab and how long it will take.

Part 1: Straws in the Colorado River: Will We Run Out of Water?

In Part 1 of this lab, students take a journey down the Colorado River to give them perspective on the scope of the watershed and how various stakeholders have siphoned the water from the river to serve seven western states' needs. Then they collect data concerning where the water comes from, who is using the water and how much they are using, and what the future may hold for the people living in the basin.

Part 2: Explore the Colorado River Basin

In Part 2 of this lab, students explore aspects of the Colorado River Basin using a video, interactives and tools such as Google Maps.

Part 3: Understanding Long-term Stream Flow Using Tree-ring Science

In Part 3, students explore several tree-ring sites and work in teams and use a quantitative method to measure the width of tree rings (using ImageJ) to produce a graph of the climate record in the Colorado River basin over the past 120 years. Then they compare their results with stream flow data to determine how good a proxy tree rings are for measuring changes in the flow volume of the Colorado River.

Example student Powerpoint (download PPT (PowerPoint 2007 (.pptx) 19MB Mar20 19))

Printable Materials

Download and print files needed for each part of the lab, including student handouts and answer keys.

To download one of the PDF or Word files below, right-click (control-click on a Mac) the link and choose "Save File As" or "Save Link As."

Student Activity Sheet for Lab 4 (PDF (Acrobat (PDF) 232kB Mar14 19))(Word (Microsoft Word 2007 (.docx) 68kB Mar14 19));
Suggested Answers -- educator-only file

Suggested Answers

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Example student Powerpoint (download PPT (PowerPoint 2007 (.pptx) 19MB Mar20 19))

Teaching Notes and Tips

What you need to prepare ahead of time, and general recommendations for classroom implementation.

To add a hands-on component, consider purchasing a core apparatus (about $240) Forestry Suppliers. Visit The Ultimate Tree-Ring Webpages for tips, advice on cleaning kits for your core apparatus, and more information.
Have ImageJ downloaded on all student computers or give them the link to download it themselves.
If you would like students to learn the rudiments of ImageJ on an individual basis have them go through the ImageJ Beginner's Tutorial.
Go through each section of the lab. Download and print the student worksheets unless students are going to print themselves at home.
Go through each section of this part of the lab. Students may need help interpreting some of the graphs and figures.
Familiarize yourself with the Colorado River Basin Interactive Map.
If students have never used Google Maps before, take them through a short tutorial of how to navigate in the program and how to type a location in the Search Box to go to a specific location.
In Part 3, students will work in small groups. Divide the students into groups of four or five. Each group will be assigned one of the three study sites to focus on. When they are in their groups, they should elect a member to act as the "PI" (principle investigator) of their research group. The PI will organize and guide the completion of your final report. Then group members should decide who will act as:
Data crunchers - the member(s) who will use ImageJ to measure and record the data from two core samples taken from a single tree on your study site.
Tech person - the member who will be responsible for producing the graphs of the data in Excel or similar program and will procure the necessary images for the report.
co-PI - the member who will assemble the various parts of the presentation with the PI and produce the PowerPoint of the group's results and final report.
If students are not familiar with measuring on images with ImageJ, have them review the ImageJ tutorial found here.
If you are not familiar with measuring on images with ImageJ, review the ImageJ tutorial found here.
Decide how you want to divide the dataset, the number of decades of tree ring data that your students will measure using ImageJ. You can have students select their own interval of rings or you can assign them. Keep in mind that either the students or you will need to assemble all the parts of the data and create a graph for the class to analyze and discuss.
Bring up the image and go through how to set scale and take a sample measurement if possible.
- Climate Fluctuations, Drought, and Flow of the Colorado River (2004) Webb, R., Hereford, R., McCabe, R. USGS Factsheet https://pubs.usgs.gov/fs/2004/3062/
- Climate Change Impacts on Hydropower in the Colorado River Basin (2012) Thiel, Aaron/Center For Water Policy/University of Wisconsin-Milwaukee
- Gray, S. T., J. J. Lukas, and C. A. Woodhouse (2011), Millennial-length records of streamï¬‚ow from three major Upper Colorado River Tributaries 1, J. Am. Water Resour. Assoc., 47(4), 702â€"712.
- Jacoby, G. C., and C. W. Stockton (1976 ), Long-term surface-water supply and streamï¬‚ow trends in the Upper Colorado River basin based on tree-ring analyses, Natl. Sci. Found. Lake Powell Res. Proj. Bull., 18, 70.
- Meko, D. M., C. A. Woodhouse, C. A. Baisan, T. Knight, J. J. Lukas, M. K. Hughes, and M. W. Salzer (2007), Medieval drought in the upper Colorado River Basin, Geophys. Res. Lett., 34, L10705, doi:10.1029/2007GL029988.
- Woodhouse, C. A., and J. J. Lukas (2006), Drought, tree rings and water resource management in Colorado, Can. Water Resour. J., 31(4),297â€"310.
- Woodhouse, C. A., S. T. Gray, and D. M. Meko (2006), Updated streamï¬‚ow reconstructions for the Upper Colorado River Basin, Water Resour. Res., 42, W05415, doi:10.1029/2005WR004455
- Drying of the West, National Geographic. February 2008. By Robert Kunzig, Photographed by Vincent Laforet http://ngm.nationalgeographic.com/2008/02/drying-west/kunzig-text
- TreeFlow (a comprehensive web resource for tree-ring reconstructions of streamflow and climate, providing easy access to reconstruction data as well as information about how the data were developed and can be used): http://www.treeflow.info
- TreeFlow: Colorado River Streamflow: A Paleo Perspective http://www.treeflow.info/perspective
- IPCC Report, Chapter 2 - Future Climate Changes, Risks, and Impacts
- David, Owen, Where The River Runs Dry, New Yorker May 25th, 2015 Issue: https://www.newyorker.com/magazine/2015/05/25/the-disappearing-river

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TREX

Tree-Ring Expeditions

Educator Guide Lab 4: Sharing a River: The Colorado River Story

Summary and Learning Objectives

Learning Objectives

Activity Overview and Teaching Materials

Printable Materials

Teaching Notes and Tips

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