Exam (elaborations) GIZMOS Student Exploration River Erosion

Exam (elaborations) GIZMOS Student Exploration River Erosion Vocabulary: cutbank, discharge, erosion, flood, floodplain, meander, meandering river, oxbow lake, point bar, river speed, sediments, slope, streambank, streambed, tributary, weathering Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. The image above shows a raging mountain river in full flood. What do you think is making the water brown in color? Mud from the mountains 2. What impact do you think the flooding river will have on the surrounding landscape? It can damade buildings and electrical systems. Gizmo Warm-up If you stand by the bank of a river, it may seem that very little is happening. But over thousands and even millions of years, rivers can have a profound effect on the landscape. In the River Erosion Gizmo, you will see how rivers move materials and how they affect landscapes. To begin, check that Mountain stream and Short-term erosion are selected. The Gizmo shows a typical stream that is moving through a hilly area. 1. The two movie cameras ( ) allow you to observe different parts of the stream up close. Click on the left movie camera. What do you see? fish swimming over bolders in the river. 2. Sediments are small rock fragments such as sand or pebbles. What evidence do you see that sediments are being transported? where the river is leading to 3. Now select the right movie camera to see the bank of the mountain stream. What is happening to sediments on the bank? they are falling down the river Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :44:25 GMT -05:00 This study resource was shared via CourseH GIZMOS Student Exploration River Erosion Activity A: Mountain streams Get the Gizmo ready: ● Check that Mountain stream and Short-term erosion are selected. ● If necessary, click outside the circle to close the zoomed-in view. Introduction: Erosion occurs when sediments and other materials are moved from one place to another. Along with weathering, which is the breakdown of large rocks into smaller sediments, erosion can have a profound impact on the landscape. Question: How does river erosion affect landscapes in the mountains? 1. Label: First, get to know some of the different parts of a mountain stream. Turn on Show labels. ️Label the image to the right, then fill in the word that goes with each description. A small stream that flows into a larger stream: tributary A place along a stream where water drops straight down: water fall A letter that describes the shape of a typical mountain valley: v shaped The side of a stream: stream bank The bottom of a stream: stream bed 2. Observe: Turn off Show labels. Next to “Release barrel,” click Play ( ). Observe how fast the barrel moves as it floats down the stream. What happens when the barrel goes over the waterfall? speeds up 3. Calculate: The two red flags are 100 meters apart. The time at which the barrel passes the flag is shown. Remember, there are 60 seconds in a minute. A. How many seconds did it take for the barrel to go 100 meters? 3:09 min B. To find the barrel’s speed, use a calculator to divide the distance traveled (100 m) by the time it took the barrel to float 100 m. The units are meters per second (m/s). What is the speed of the barrel? 1.89 m/s Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :44:25 GMT -05:00 This study resource was shared via CourseH 4. Record: Click Reset ( ). Turn on Show data. A. The slope of the channel is how steep it is, or how many meters the streambed drops for every horizontal kilometer. What is the slope of the stream? 22m / km B. River speed is a measure of how fast water flows. What is the river speed? 1.1 m/s C. How does the river speed compare to the speed of the barrel you calculated on the previous page? The barrel was faster than thwe river D. Discharge is the water volume that flows past a given point every second, measured in cubic meters per second (m3 /s). What is the stream’s discharge? 2.3 m^3/s E. What types of sediments are transported by this stream? sand,silt,and clay Sediments are classified by size. The smallest sediments are clay particles, followed by silt, sand, and pebbles. Larger sediments include cobbles and boulders. 5. Observe: Turn off Show data. Next to River flow, select Flood. Look at the landscape, and then click on the movie cameras to see zoomed-in views. Describe what you notice below. It shows the river way dirtier than the sediment moving. 6. Calculate: Click Play to release the barrel. How many seconds does it take the barrel to get from one flag to the other? What is the speed of the barrel? Time: 2:04 Speed: 1.24 7. Compare: Turn on Show data. During a flood, how do the river speed, discharge, and transported sediments compare to normal flow conditions? The river speed and discharge is way faster than theirs pebbles now in the river. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :44:25 GMT -05:00 This study resource was shared via CourseH Activity B: Meandering rivers Get the Gizmo ready: ● Select Meandering river. ● Select Short-term erosion, Low vegetation, and Normal river flow. Turn off Show data. Introduction: Meandering rivers are found in flatter areas. Unlike the V-shaped mountain valleys, the valleys of meandering rivers have wide, flat bottoms called floodplains. Question: How does river erosion affect landscapes in hilly or flat areas? 1. Label: Turn on Show labels. ️Label the image to the right, then fill in the word that goes with each description. A large S-shaped bend in a river: meander A flat area next to the river pointbar A steep stream bank on the outside of a bend in the river: cut bank A gently sloping deposit of sediments on the inside of a bend in the river: 2. Observe: Turn off Show labels. Click Play to release the barrel. Observe the path of the barrel as it floats down the river. (The flags are 100 meters apart.) A. How many seconds did it take for the barrel to go 100 meters? (Remember, there are 60 seconds in a minute.) 125 seconds B. What is the speed of the barrel? 0.8m/s C. Turn on Show path. Did the barrel stay in the center of the river or go from side to side? it moved from side to side D. As the barrel went around each meander, did it stay closer to the point bars or the cutbanks? it got close to the cutbanks because it was on the outer edge of the stream getting pushed. In a meandering river, the water flows faster on the outside of a meander, near the cutbank, and moves more slowly near the point bar on the inside of the meander. The current carries the barrel toward the cutbanks and away from the point bars. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :44:25 GMT -05:00 This study resource was shared via CourseH 3. Compare: Click Reset. Turn on Show data. List the slope, speed, discharge, and transported sediments of the meandering river. Then select Mountain stream and fill in the remainder of the table. Change back to the Meandering river and compare the values. Meandering river Mountain stream Slope 1.0 m/km 22.0 m/km Speed 0.8 m/s 1.1 m/s Discharge 187 m3/s 2.3m3/s Transported sediments silt,clay cut banks sand ,silt,clay In what ways is a meandering river different from a mountain stream? 4. Observe: Turn off Show data. Click the right movie camera to see the cutbank. Look at the sediments just above the water. What do you see? i see a lot of little things moving down the stream Now select the left movie camera to see the point bar. Look at the sediments in the water. What do you notice? there are less sediments in the pointbar than the cut bank. Erosion occurs at the cutbank, where water is moving faster. As a result, cutbanks are ste