Hot deserts (2 case studies - The Sonoran and The Thar)

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  • Created by: Kelleigh
  • Created on: 02-06-13 15:24

General information

Distribution - Northern Africa, Australia, Central America, West Coast of South America - Dry areas of the world (continental interiors, e.g. above the tropic of cancer and capricorn, 30 degrees north and south of the equator)

Climate - Air descends giving high pressure - Arid climate controls life - Persistant high pressure (blue sky conditions) means no clouds or rain - Less than 250mm of rainfall per year

Soils - Soil is arid due to little rainfall - Soils rapidly soak up the little rainfall - Evaporation draws salts to the surface (leaving white residue) - There is little organic matter, soils are very sandy and stony, they are not fertile

Vegetation - Desert yellow daisy (small leaves that are hairy and succulent (hairs capture moisture,  leaves maintain moisture)) - Sagebrush (roots 25m to get deep water supplies, needle leaves reduce surface area, so water loss too) - Joshua Tree (waxy resin reduces water loss) - little organic matter due to little vegetation which means nutrients aren't returned to soil - Plants struggle to grow (salty soil) - Saguaro Cactus (roots close to surface to soak up water before it evaporates, skin is pleated to allow expansion when its full, grows slowly so doesn't require much energy

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The Sonoran Desert, Arizona, USA (MEDC case study)

One of North America's largest, hottest and wettest deserts - 300mm of rainfall

It is located in south-west America (Arizona, California and Mexico)

It is beautiful, great diversity of flora and fauna, including the saguaro cactus

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The Sonoran Desert, Opportunities

Cotton agriculture continues to sustain economic and cultural value (new irrigation systems) - 15 cotton mills (In Marana)

Residutial and commercial growth

Extensive park and trail systems provide outdoor opportunities

Fantastic education = high success

Retirement area (new retirement complexes with swimming pools and golf courses) but also youth and families

PGA golf tours (2007) - wealthy activities, prestige and tourism

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The Sonoran Desert, Management

There is a strong sens of pride that keeps the community going (cotton mills)

Everyone can live, grow and work all in the same community as there is a diversity of opportunities

There is a town centre, tree lined streets, homes, restaurants, jobs and a business community

Education, Business, Community and leisure = makes it sustainable for economic growth. High achieving "probusiness" mindset

Highways are crucial to economic growth, growth is balanced with environmental factors (stewardship is employed, conservation strategies and water renewable sources)

The challenges are easily overcome (MEDC), e.g. air conditioning and the piping of water

Home design - "Desert House" - Desert Botanical Garden in Phoenix, Arizona

Housing developments are close to exsisting ones, no hillside developments - fragile environment

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The Thar Desert, Rajasthan, India (LEDC case study

One of the major hot deserts in the world

Stretches across north west India and into Pakistan, covering 200,000kmsquared

rainfall is low - 120 - 240mm per year

the summer temperatures can reach 53 degrees celcius

It is sandy hills with extensive mobile sand dunes and clumps of thorn forest vegetation, a mixture of small trees, shrubs and grasses

The soils are generally sandy and not very fertile, as there is little organic matter to enrich them

Soils drain quickly so there is little surface water

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The Thar Desert, Economic opportunities

Subsistence farming - is very popular - a few animals on grassy areas, fruit trees and cultivating vegetables (not much variety (limited range)) - Some crops are sold at local markets - crops feed family - gives small money for clothes and food - it's unreliable - Hunter gatherers (collect honey, Kohlis tribe in Pakistan region of Thar)

Tourism - Camels in Jaisalmer - desert safaris - beautiful landscape - local people benefit from acting as guides and looking after camels

Mining and industry - Gypsum (stone, limestone - steel) is used for plastering for construction companies - wool and leather - phorpherite (horse manure) - Kaolin (paper whitening) - feldspar (ceramics) - local hide and wool

Irrigation and commercial farming - Indira Gandhi canal (650km) helps Jodphur, Jaisalmer and 3,500km cubed of land is irrigated

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The Thar Desert, management

Stabilising dunes - very mobile dunes - planting blocks of trees and establishing shelterbeds of trees and fences alonside roads and canals - a threat to farmland, roads and waterways

Forestry - Ber tree (large fruits are sold for a profit, low rainfall, created by scientists - hardy breed of plum) - Prosopis cineraria (well adapted to hostile conditions, very important)

1977 - In Rajasthan, a big concern was mobilising sand dunes, a government funded 'Desert Development Programme' - main aims were to restore the ecological balance by conserving, developing and harnessing land, water, livestock and human resources

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The Thar Desert, Challenges

Tourism (desert becomes over-developed), Unreliable rainfall, fragile desert ecosystem, frequent droughts

Population pressure - overgrazing and overcultivation - most populated desert in world (83 people/km squared) - increasing population

water management - excessive irrigation - poisonous salts (to plants) are deposited on the ground (salinisation) - unsustainable fall in water table

soil erosion - takes thousands of years to reform - overgrazing and overcultivation have damaged vegetation, leads to erosion by wind and rain

Fuel - use manure (rather than using to improve soil quality) - reserves of firewood are the main source of fuel

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