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Whitewater Rafting by Rasheed, Kohner, Scotty, and JB

We love the splashy thrills of the American River. We noticed how different the rapids were from the calm parts of the river, and wondered how the same river could have such differences in it. Our question: what makes the water flow differently in the rapids compared to a calmer stretch of river? How can we use what we learn to help us become better whitewater rafters?

What did we do?
We compared a calm stretch of the river with an active rapid, and measured the river elevation change and water speed in each. Then we investigated river obstacles such as tongues, eddies, and holes. We also checked out how different paddling styles affected our navigation abilities. As the final test, we rafted through Satan's Cesspool, a rockin' Class III rapids at the end of our trip.

What did we find out?
For the calm versus active waters, we found a greater elevation change in the rapid areas than in the calm stretch. We found that the water around tongues, eddies and holes pushes our raft around in various directions, which helped us avoid getting dumped into the river. Finally, we learned that there is a time and a place to back paddle and forward paddle. For example, you might want to back paddle through an eddy, and forward paddle through a tongue.

What can you do?
• When rivers carve out a path, they tend to "meander," which means that they snake back and forth. Make a river model with sand in a jelly roll pan. Tilt the pan, pour water slowly at the top, and watch how the water carves out a meandering river.

• One interesting feature of river rapids is called an "eddy," a calm spot on the backside of a large boulder in the river. If you want to find eddies indoors, use a room fan and place objects in front of it. Use a streamer on a stick to show how the air flows around the object.

• How does the temperature of water in a lake or stream differ at different depths? Design an investigation to find out.

• Use this earth science investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!