Deserts

• Found between 20' north and 30' south of the equator - hot dry air sinks and causes cloud free conditions
• rain = low = less then 250mm per year
• extremely hot during the day but cold at night - no clouds to insulate and stop heat loss - daily temperatures (diurnal) can range between 35-40' in the summer
• deserts are dry and arid with little vegetation
• Vegetation and soil


  soil - dry and not very fertile, due to lack of rainfall and sparse vegetation, there is little decomposing matter to enrich the soil - nutrients decay quick because of high temperatures

  only limiter number of plants can survive the harsh conditions
• due to the harsh conditions, soil is poor and biodiversity is low - only adapted thing can survive

  desert people are often nomadic (keep moving for food and water) - they grow crops when they can, and rely on animals such as goats and camels for food and transport
• Cactus adaptations

  • wide spread root spread
  • spines instead of leaves
  • stems that can store water
  • small surface area that can minimise evaporation
  • sharp spines to deter thirsty animals
• camel adaptations

  • nostrils that can close - keep sand out
  • double eye lashes - protect eyes from sand
  • leathery mouth helps camels to eat spikey plants
  • store fat in their humps to sustain themselves when food and water is scarce
  • hair on back - protect against sun
  • long legs - keep camel off sand so it can stay cool
  • leather pads to protect the bottom of their feet and to stop them from sinking
  • very concentrated urine to minimise water loss
• Thar desert - location

  • border of north India and East Pakistan
  • continent - Africa
  • South west of Himalayas
  • lies between Tropic of Cancer and the Equator
• Thar desert - development

  Tourism

  • tens of thousands of people visit each year - brings money to Pakistan
  • camel rides
  • annual festival each winter - local people benefit - provide food and accommodation by acting like tour guides
• Thar desert - challenges

  Tourism

  • litter
  • high temperatures
  • water supply = scarce -> more people = less water
• Thar Desert - development

  farming and agriculture

  • survive in hot desert conditions by grazing animals on the grassy areas and cultivating fruit and veg
  • commercial farming - grown over decades by irrigation
  • construction of Indira Gandhi Canal in 1958 revolutionised farming crops, such as wheat and cotton - they now thrive
• Thar Desert - challenges

  farming and agriculture

  • lots of water used up for plants to grow - water supply = scarce
  • high temperature = plant die
  • water used for animals drinking water
• Thar Desert - development

  energy production (wind turbines)

  • rich energy resources:

  coal

  oil

  wind

  solar
• Thar desert - challenges

  energy production (wind turbine)

  • takes up space
  • produces Carbon Dioxide
  • not sustainable resource
• thar desert - development

  mineral extraction

  • desert regions has valuable reserves of mineral -> used in India, exported all over the world
  • most important:

  gypsum (used in construction (plaster))

  feldspar (ceramics)

  phosphate (fertilisers)

  kaolin (whitener in paper)

  limestones
• Thar desert - challenges

  mineral extraction

  • takes time - outside in hot conditions for long periods of time
• desertification


  the degradation of semi-arid land - a process by which fertile land becomes drier and less productive, becoming desert
• where is at risk of desertification


  every continent is at risk of desertification except from Antarctica

  Africa is most as risk
• causes of desertification

  • farming - regular ploughing dries out soil, use of chemical fertilisers damages the soil - weakens living organisms in the soil
  • overgrazing - Ethiopia
  • global warming
  • water shortages
  • strips soil of vegetation protection
  • climate change
• Impacts of desertification

  • sand storms
  • reduces world food population - less fertile land - more people less food - 200 million tonnes of cereal lost per year
  • 110 countries are effected
  • gullying
  • cracks inland
  • effects everywhere
  • death
  • a third of the land is at risk
  • migration (social)
• How to reduce desertification


  technology needs to be;

  • appropriate for people
  • affordable
  • appropriate for the place
  • sustainable
• Sanell desert 


  the Sanell desert is the region at the greatest risk of desertification
• The Great Green Wall


  7100 km long

  15km wide

  belt of vegetation and tree's to stop the spread of desert

  location - North Africa, stretches from west to east, over 20 countries (eg Nigeria, Senegal, Chad, Ethiopia, Mali) - from the Atlantic ocean to Red Sea
• How does plant trees help against desertification

  • why is it happening in Senegal - overgrazing, deforestation, over farming, climate change (droughts)
  • Senegal's environment - bare, dry
  • Acacia Tree Project - plant trees, tech people how to plant, sew and harvest
  • this Project helps as it prevents soil deprivation
  • effects on people - gives job, helps mentally, produces products to sell, source of income
• Great green wall


  symbol of hope

  launched in 2007 to restore Africa's degraded landscape

  once complete - over 8000km of nature

  20 countries

  8 billion dollars invested
• Great green wall - objectives


  by 2030 - restore 100 million Ha of land, sequester 250 million tonnes of Carbon, create 10 million jobs

  climate resilience

  grow fertile land

  economic opportunity

  food security
• Great green wall - results 2020

  • Ethiopia - 5.5 billion planta
  • Senegal - over 18 million trees planted, 800000Ha of land restored
  • Nigeria - 8 million trees, 1396 jobs
  • Sudan - 200Ha of land restored
  • Burkina Faso - 16 million trees planted
  • Mali - 135000 plants
  • Eritrea - 129 million trees
  • Niger - 146 million trees
• Great green wall 


  tree's need to be far apart for water
• great green wall - negatives 


  takes time

  lots of countries have to agree