U-Shaped Oxbows at Chichaqua Bottoms Greenbelt

This video shows and discusses the oxbows (U-shaped river bends) at Chichaqua Bottoms Greenbelt, which was formerly a part of the South Skunk River before the river was channelized.

• How did the oxbows get to be such a funny shape?

• Why aren’t all rivers that curvy?
• How long did it take to make the oxbows?
• Why is this water slow but other water is fast?

Students could:

• Develop initial models in pairs of how they think the oxbow might have formed. Students can share these models and after investigations and/or research to come to an answer, have students develop a whole-class consensus model.
• Compare and contrast oxbows with streams, rivers, and other familiar bodies of water.
• Experiment with stream tables to try to form oxbows.
• Identify evidence of weathering and erosion around your school or students’ homes.
• Compare a meandering river to a time-lapse of Chichaqua Bottoms from Google Earth. Discuss what’s different between the two scenarios - why are the “meandering rivers” changing and Chichaqua Bottoms not? Students may consult maps or research the area’s history to find out.
• Discuss the recommendation to re-connect Chichaqua Bottoms with other oxbows so the flow can be restored. Have them discuss and draw out what might happen to the oxbows if this happens.
• Introduce students to the phenomenon of Carter Lake, Iowa. Have them discuss similarities and differences between this case and the Chichaqua Bottoms oxbows. 
• Have students research examples of rivers being changed by both gradual and catastrophic processes.

• Des Moines Metropolitan Planning Organization/Iowa Department of Natural Resources | A Vision for South Skunk River and Chichaqua Bottoms Greenbelt: Describes how the area can be used for water trails purposes.
• Polk County Conservation | Chichaqua Bottoms Greenbelt Management Plan 2016-2036: Teacher background - gives extensive information on how the county plans to reconstruct the oxbows and other areas of Chichaqua.
• PBS LearningMedia | Science Trek: Rivers: Life of a River: Video explaining how rivers change over time.
• Google Earth | Google Timelapse: Zaragoza River:Timelapse is a global, zoomable video that lets you see how the Earth has changed over the past 32 years.
• Iowa State University Extension | The Iowa Watershed Approach - Oxbow Restoration: Short flyer on oxbow restoration projects in Iowa.
• Iowa PBS Explores | Cut-Off Lake: A piece of Iowa land a little over two square miles sits snugly in Omaha, Nebraska. Learn the colorful, confusing history involving floods, legal battles, and cessation of Carter Lake, Iowa.