hot deserts

• Thar Desert development opportunities:

  • farming
  • mineral extraction
  • tourism
  • energy generation
• farming:

  • commercial farming made possible by irrigation through the Indira Gandhi Canal 
  • crops grown like: wheat, cotton, maize, mustard, pulses
  • boosts economy by providing jobs for people and generated income plus gives food to locals
• Mineral Extraction:

  desert has valuable reserves of minerals like:

  • gypsum (plaster for making cement)
  • feldspar (used to make ceramics)
  • phosphorite (makes fertiliser)
  • kaolin (whitner in paper)
  • limestone (building and producing cement)
  • marble (construction)
• Tourism: 

  • Thar Desert National Park (120 species found there)
  • explore desert with local guides on camels
  • important source of income and creates jobs 
  • multiplier effect (when a positive change happens, which then has a knock-on effect on other businesses. For example a new office may open, which leads to an increase in lunchtime sandwich sales at the local café and more bus passengers)
• Energy Generation:

  • energy produced using solar panels
  • energy used to clean water supplies contaminated with salt (desalination)
  • wind energy from turbines used to generate electricity 
  • Jaisalmer Wind Park is India's largest wind farm 
  • extensive coal deposits 
  • thermal energy plant constructed at Giral
  • oilfield discovered in Barmer 
  • important resources for the locals and good source of income as can sell to other countries and have an industry, plus renewable energy sources helps environment
• Thar Desert development challenges:

  • extreme temperatures
  • limited water supply
  • inaccessibility
• Extreme Temperatures:

  • can exceed 50°C
  • tarmac can melt leading to limited transport
  • lack of water limits farming 
  • hot sand so hard to walk 
  • difficult for people to function overall 
• Water supply: 

  • limited (120-240 mm of rain annually)
  • without water the development of mining, farming and tourism and therefore the economy would not be possible
  • some parts of desert have over-irrigation so causes waterlogging ( water that submerges land and makes it marshy)
  • high temperatures mean water evaporates and leaves layer of salt on surface making it hard to grow crops 
  • rivers and streaks are 'intermittent' (occurring at irregular intervals) dry up in hot weather and recover after rainfall 
• Inaccessibility:

  • most of desert is inaccessible 
  • extreme environmental conditions and poor infrastructure 
  • honeypot (popular) site for tourists in Jaisalmer (could be good for income there)
  • greater differences between rich and poor hinder overall development 
  • some areas are more developed than others
• characteristics of hot deserts:

  • heat: up to 49°C
  • dry: less than 250mm rainfall annually
  • large diurnal temperature range (happens over a period of a day cause less clouds so sun directly heats surface during day and heat is lost at night)
  • soils: sandy, rocky, crusty in appearance due to hot water evaporating and reaching the surface leaving a layer of salts
  • less vegetation: species of animals and plants adapt because salts on surface means less vegetation
• distribution of hot deserts:

  • 15°-30°N and 15°-30°S latitudes 
  • Hadley cells near the equator 
  • high pressure area (cold air sinks so clear and dry skies)
• plant adaptations: acacia trees, cacti, ephemerals
• acacia trees:

  • short fat trunks to store water
  • pyrophoric (fire resistant)
  • long tap roots (50m) for groundwater 
• cacti: 

  • succulent (store water)
  • spikes (deter consumers)
  • spines (reduce water loss by transpiration)
  • transpiration = water vapour exits through stomata of leaves)
  • waxy skin (retain water)
  • widespread roots (water)
• ephemerals:

  • seeds stay dormant for long time
  • complete life cycle very quickly (short life cycles)
  • bright colours attract insects
• animal adaptations: desert fox, kangaroo rat, perentie, thorny devil, desert tortoise
• desert fox:

  • thick fur on feet (protect from heat)
  • light fur (reflects heat)
  • large ears (dissipates heat)
• kangaroo rat:

  • don't sweat (reduce water loss)
  • produce little urine
  • live in burrows during day
  • nasal counter flow 
• perentie:

  • shelters underground 
  • climb termite mounds or shrubs to get off hot ground 
• thorny devil:

  • tiny grooves over body (direct moisture to mouth)
  • camouflage 
• desert tortoise:

  • dormant during hottest part of summer (aestivation)
• soil erosion is the wearing away of surface soil by water and wind so there are no more nutrients for plants to grow
• causes of desertification:

  • overgrazing
  • over-cultivation
  • lack of rain
  • deforestation from demand for fuelwood
• overgrazing:

  • too many animals
  • plants die
  • soil exposed
  • no new plants
  • soil erosion
• over-cultivation:

  • soil loses nutrients
  • no plants
  • soil erosion
• lack of rain:

  • plants die
  • soil exposed
  • no new plants
  • soil erosion 
• deforestation:

  • trees cut down
  • less trees protecting soil
  • soil exposed
  • no new plants
  • soil erosion
• reducing desertification methods:

  • bunds
  • planting trees
  • renewable energy
• bunds:

  • rocks place along contours of land parallel to gradient of a slope
  • holds water on soil rather than letting it run quickly over the surface 
  • controls destructive force of rainwater
  • retains topsoil preventing soil erosion
• planting trees:

  • holds soil together and protects from rain 
  • provides nutrients so other trees and plants can grow
• renewable energy:

  • lowers trees cut down
  • sold to other countries for profit 
  • increases power supply without increasing carbon emissions
• desertification: the process by which deserts are formed through degradation of land when the soil is eroded, the vegetation is destroyed and bodies of water and therefore wildlife is lost.

  • areas on the borders of existing deserts are most at risk
• a desert is an area that receives less than 250mm of rainfall a year