Lab 08 Meandering Rivers

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Open the Lab 08 Meandering River.KMZ file in Google Earth. 1. Now fly to Yakeshi, China (Question 1 on the KMZ file). Just north of the city is a beautiful series of scroll bars (former point bars that have been abandoned) formed by the meandering river moving across the landscape. a Describe what you are seeing here. (How are the meanders moving over time? Is the river becoming straighter or more curved?) b How long is the river through a particular reach compared to the birds-flight distance? (For this you’ll want to measure along the river and then measure a straight line between those two end points.) This ratio (river length divided by straight line length) is called the sinuosity of the river. Provide an image from GE of the river section you measured. Include your paths (be sure to make the lines wide enough to be visible and different colors) in the image. Below your image present your calculation of the sinuosity of the river for your selection. Figure 1. Meandering river terms. Image from: http://www.sierrapotomac.org/W_Needham/MeanderingRivers.htm Earth Science Online Lab 08 Worksheet Meandering Rivers 2. Other important measurements for meandering rivers include the radius of curvature, amplitude, and wavelength. a Using the information from figure 1 on the last page, describe in words what the wavelength, radius of curvature, and amplitude are. b Calculate these values for the river outside Yakeshi on a section that has at least 3 waves. 3. Fly to the Green River in Washington state. (Question 3 on KMZ file) There should be a little button labeled 1990 in the lower left of the screen. Click on that. You’ll notice that the image changes back to 1990 and a tool bar with dates shows up in the upper left of your screen. You can use the arrows on this toolbar to scroll through images taken at different time. There are 24 images at this site over a period of 29 years. For one image for each year of photos (so only one of the two 2007 images, for example), use the line drawing tool to trace the main channel of the Green River across your screen in the area contained within the white box. Describe how the river has moved over time. Measure how far it has moved between the 7/1990 and 5/2019 images. What are the sinuosity, amplitude, radius of curvature, and wavelength here for the two images you looked at? Did those values change over time? 4. Fly to Harbin, China (Question 4 on KMZ file). This isn’t too far away from Yakeshi and also has scroll bars. What is sinuousity, amplitude, wavelength, and radius of curvature here? How is this, much larger, river changing over time? Provide evidence to support your answer. 5. Now we’re going to look at meandering rivers in bedrock (seriously – they are really cool). Fly to Wutai, Taiwan (Question 5 on KMZ file). You should be looking down at a mountainous landscape with some seriously meandering rivers. Fly around the landscape. How do the sinuousity, amplitude, wavelength, and radius of curvature here differ from the flatter rivers in Yakeshi and Harbin? What process is forming the meanders here? In other words, how on earth do you get a river to meander in bedrock? Note that the rivers are not running on the top of the mountains – this is an optical illusion that has to do with where the sun is when the image was taken and where you expect it to be. You can turn on Terrain to make a 3D image give a more realistic view, if you computer has a slower processor or internet bandwidth, this might make maneuvering slower. 6. Now we’re going to be a little closer to home. Fly to Carlisle Reservation, Ohio (Question 6 on KMZ). Do you see any evidence of the meander bends moving? What is change in the sinuosity, wavelength, amplitude, and radius of curvature here? Has there been much change? Why do you think this is the case? Earth Science Online Lab 08 Worksheet Meandering Rivers 7. Now that you’ve looked at so many rivers, please compare and contrast the processes going on in Yakeshi, the Green River, Harbin, Taiwan, and Carlisle Reservation. Take into account the geology, climate, and anthropogenic setting of the sites. For example, be sure to look for dams upstream of locations. You may want to ask the internet for help with the geologic/climatic setting of each site. Create a comparison table for this using the following format. River Name and Location Geology Climate Anthropogenic Setting Sinuosity Wavelength Amplitude Radius of curvature