Lab 8: Eolian Processes & Arid Landscapes GEOG 1113L – Introduction to Landforms Lab Name: __Anora Oromoni ___________ I. Wind Transport and Dunes 1. Describe the difference between suspension, saltation, and surface creep. Suspension is what happens when the sand particles get suspended in midair. These particles are small and light enough to be carried high into the atmosphere, where they can be transported long distances. Saltation happens when larger particles are transported in short distance jump along a part. These particles are too heavy to be suspended, but they can be dislodged from the surface by wind and bounce along the ground. Surface creep happens when exposed sand is pushed or rolled along the ground. These particles are too heavy to be suspended or saltated, so they can only be moved by rolling or sliding along the surface. 2. Which type of wind transport contributes the most to the formation of dunes? Saltation 3. What shape does a barchan dune have? crescent-shaped sand dune 4. When a barchan dune comes across winds moving in two directions, incredibly long dunes can form, which are called what? Linear dune 5. When the wind is perpendicular to the crest of the dune, the dune is called what? Transverse dune 6. As seasons change and wind blows in different directions, what type of dune will form? Star dune 7. Which dune has a U shape and forms from unidirectional wind and the presence of vegetation? Parabolic dune 8. Name three types of obstacles that can drive the formation of dunes. Vegetations, Cliffs, hills, and manmade obstacles. 9. Match the term with its proper definition. __C__ Complex Dune A. The most basic form of a dune. __A__ Simple Dune B. The same type of dune superimposed onto one another.

__B__ Compound Dune C. Different types of dunes overlapping one another. 10. Name three important factors that drive dune formation. Time, wind regime, and sand supply. II. Dune Profile Read the definitions/hints within the diagram below and use them to determine which of the terms provided below should be placed in each blank box. Direction of Dune Movement Successive slip faces created as dune migrates Leeward Slope Slipface Windward (Stoss) Slope Previous Slip Faces Effective Wind Direction

III. Case study: The Disappearing Aral Sea The Aral Sea was once the fourth largest lake in the world. Over the last several decades, the lake decreased in size by more than 80% and the Southern (larger) Aral Sea disappeared altogether. This disappearance had devastating effects on communities in the region. Go to NASA’s Earth Observatory site and read the article for “Shrinking Aral Sea” at https://www.earthobservatory.nasa.gov/world-of-change/AralSea . As you watch the timelapse clip, you will see dramatic changes in the aerial extent of the Aral Sea. 1. When did the Aral Sea begin to shrink? What caused the Aral Sea to shrink? The Aral Sea began to shrink in the 1960s. It was caused by the diversion of water from the Amu Darya and Syr Darya rivers for agricultural irrigation. 2. How has the shrinking lake affected the quality of the water and farmland in the region? The shrinking of the Aral Sea has had a devastating impact on the people and environment of the region. The poor water quality and salinized farmland have made it difficult for people to live and farm. As the Aral Sea has dried up, fisheries and the communities that depended on them collapsed. The increasingly salty water became polluted with fertilizer and pesticides. The blowing dust from the exposed lakebed, contaminated with agricultural chemicals, became a public health hazard. 3. How has the lake’s loss affected local summer and winter temperatures? The loss of the moderating influence of such a large body of water made winters colder and summers hotter and drier. Step forward in time to see changes in the Aral Sea. The green region is the lake and the white region around the lake is the result of salt deposits. The yellow boundary around the sea is the approximate shoreline of the Aral Sea in 1960. Utilize the scale bar in the lower right corner of the images to approximate distances. 4. What was the distance between the eastern edge of the Aral Sea in 1960 and the western edge of the Southern Aral Sea in 2000? Compared to 2005? Compared to the distance in 2010? And, in 2015? The distance between the eastern edge of the Aral Sea in 1960 and the western edge of the Southern Aral Sea decreased significantly over time, from 200 km in 2000 to 0 km by 2010. The Southern Aral Sea remained dry in 2015. This is because the Aral Sea has been shrinking rapidly since the 1960s due to the diversion of water from its two main tributaries, the Amu Darya and Syr Darya rivers, for irrigation purposes. 5. What was the distance change between 2000 and 2005? Between 2005 and 2010? And, between 2010 and 2015? Does the rate of loss appear to be accelerating? T he distance change between 2000 and 2005 was approximately 145 km (90 miles). The distance change between 2005 and 2010 was approximately 130 km (81 miles). And the distance change between 2010

and 2015 was approximately 115 km (71 miles). Based on these measurements, it appears that the rate of loss of the Aral Sea is accelerating. 6. What is the average rate at which the Aral Sea has been shrinking between 2000 and 2018? (Remember that rate of change is the distance change divided by the number of years.) The average rate at which the Aral Sea has been shrinking between 2000 and 2018 is 200 kilometers / 18 years = 11.1 kilometers per year . Examine the image of a dust storm at: http://eoimages.gsfc.nasa.gov/images/imagerecords/19000/19853/aral_amo_2008120_lrg.jpg 7. Compare this image to the Aral Sea images from NASA’s Earth Observatory. Approximately when was the dust storm image taken (a range of a couple of years is fine)? (Hint: Compare the shape and color of the sea in the image with the images in the timelapse video. Look for the heart shaped piece.) The dust storm image was taken in 2008. This can be inferred by comparing the shape and color of the sea in the image with the images in the timelapse video. The heart- shaped piece of the sea is still visible in the 2008 image, but it has disappeared by 2014. 8. The winds in the image are blowing from which direction to which? (Hint: Think of the shape a dust cloud makes when you blow dust from the surface into the air.) The winds in the image are blowing from the southwest to the northeast . IV. Wind Erosion & Landforms For this activity, you will be looking at several images of arid and eolian landforms/processes. Terms and definitions are provided to help you decipher what each image is (all terms are used once). Open the “Lab 8 Part IV_Wind Erosion & Landforms” PowerPoint and use the “Notes” section under each image to type your answer. When you are finished, upload your completed PowerPoint activity to the Lab 8 submission folder on iCollege along with your lab assignment.

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