Gizmos Student Exploration: River Erosion

G: R: JerVohn A: Brooke B: Khai Date: 3-18-19 Group #: 28

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? Dirt

2.What impact do you think the flooding river will have on the surrounding landscape?Erosion

Gizmo Warm-up https://www.explorelearning.com/

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? I see fish swimming in the water & some rocks.

2.Sediments are small rock fragments such as sand or pebbles. What evidence do you see that sediments are being transported? How the water is flowing & the fish moving right.

3.Now select the right movie camera to see the bank of the mountain stream. What is happening to sediments on the bank? It eroded & then it fell into water.This study source was downloaded by 100000827646477 from CourseHero.com on 02-26-2022 12:49:07 GMT -06:00

https://www.coursehero.com/file/40086664/Copy-of-KWAL-5-River-Erosion-GIZMO/

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: W aterfall

A letter that describes the shape of a typical mountain valley: V_shaped valley The side of a stream: Streambank The bottom of a stream: Streambed

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? The barrel speeds up when falling down the waterfall.

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? 91 seconds 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? 1.1 m/s V-shaped valley Waterfall Tributary Streambed Streambank This study source was downloaded by 100000827646477 from CourseHero.com on 02-26-2022 12:49:07 GMT -06:00

https://www.coursehero.com/file/40086664/Copy-of-KWAL-5-River-Erosion-GIZMO/

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? 22.0 m/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? There the same

D.Discharge is the water volume that flows past a given point every second, measured in cubic meters per second (m 3 /s). What is the stream’s discharge? 2.3 ㎥/s

E.What types of sediments are transported by this stream? Sand, silt, & 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.The water level rose, it moved faster, the water got darker, the amount of sediments increased, the erosion on banks of river increased.

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: 31 seconds Speed: 3.2 m/s 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 got aster, the discharge increased, & the transported larger sediments (pebbles).

This study source was downloaded by 100000827646477 from CourseHero.com on 02-26-2022 12:49:07 GMT -06:00

https://www.coursehero.com/file/40086664/Copy-of-KWAL-5-River-Erosion-GIZMO/

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:

Floodplain A steep stream bank on the outside of a bend in

the river:

Cutbank

A gently sloping deposit of sediments on the inside of a bend in the river:

Point Bar 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? 0.8 meters per seconds C.Turn on Show path. Did the barrel stay in the center of the river or go from side to side? Side to side

D.As the barrel went around each meander, did it stay closer to the point bars or the cutbanks? Cutbanks

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.

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.Foodplain Cutbank Meander Point bar This study source was downloaded by 100000827646477 from CourseHero.com on 02-26-2022 12:49:07 GMT -06:00

https://www.coursehero.com/file/40086664/Copy-of-KWAL-5-River-Erosion-GIZMO/