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DESERTS

DESERTS. What is a desert? Where do they form? What’s happening to the world’s desert regions?. By Laura Grande. What is a desert?. Definitions vary as do deserts themselves. Most rely on rainfall and temperature analysis.

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DESERTS

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  1. DESERTS What is a desert? Where do they form? What’s happening to the world’s desert regions? By Laura Grande

  2. What is a desert? • Definitions vary as do deserts themselves. • Most rely on rainfall and temperature analysis. • Textbook: any region that receives less than 10 inches of rainfall annually and supports little or no vegetation. • Deserts can be warm or cold. • For the most part deserts are only similar in their small amounts of rain fall.

  3. Geological and topographical diversity… Red sandstone canyons: Southern Utah Chili Sand dune: Sahara Stark Granite Mountains: Arizona Coastal desert: Northern Chili

  4. Deserts cover 25% of earth’s land surface. • Modern irrigation systems have made it possible for 13% of earth’s population to live in desert regions. • 2/3 of earth’s oil reserves lie beneath the deserts of the Middle East, enabling some of the poorest nations of the world to become very wealthy. • Scientists are working to develop ways of converting desert sunlight into electricity. • Because of the arid environment, deserts are ideal for human artifacts and fossils to be preserved.

  5. Where Do Deserts Form?

  6. Desertification • The process which turns productive desert land into non-productive. • Sometimes this is caused by climate changes, but more often than not it is a result of human activity. • Cultivation of the same land year after year exhausts the soil. • Deforestation eliminates trees vital to hold the soil in the land. • Overgrazing of livestock strips away the grasses that help absorb rainfall. • No vegetation+ heat from the sun+ loose soil= land that is so impermeable that water runs off before it can be absorbed.

  7. What this creates… • Conditions more favorable for wildfires and strong winds. • This strains the plant, animal, and human life dependent on these factors. • According to the World Wide Fund for Nature, there was a world wide loss of about 30% of natural wealth between 1970 and 1995 because of desertification. • Desertification does not mean that deserts are expanding. • The Dust Bowl in America’s great plains was caused by desertification.

  8. About 3,6 billion of the world's 5.2 billion hectares of useful dry land for agriculture has suffered erosion and soil degradation. • In more than 100 countries, 1out of 6 billion world populations are affected by desertification, forcing people to leave their farms for jobs in the cities.

  9. What Can Be Done? • What used to be wasteland is now a vineyard. Ground water and underground channels have helped this vineyard flourish on land reclaimed from desert pavement in China. • Straw grids (left) and vegetation irrigated by water from a near by river stabilize dunes in China's Tengger Desert (right) to protect a nearby railroad from windblown sand

  10. Planting more green plants such as these soy beans, extract more nitrogen into the air and fix it into the soil to help make the land more fertile. • In Iran, petroleum is being sprayed over the land in semi-arid areas to give crops a coating which prevents moisture loss. • A number of schemes have been developed to help in counteracting desertification. What is important is that people realize the importance of our deserts in a global sense and stop desertification before it gets worse.

  11. Sources: • http://www.didyouknow.cd/deserts.htm • http://pubs.usgs.gov/gip/deserts/desertification/ • http://en.wikipedia.org/wiki/Desertification

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