Content Environmental Characteristics Opportunity and Constraints Human Activities in Tropical...

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  • ContentEnvironmental CharacteristicsOpportunity and ConstraintsHuman Activities in Tropical DesertDesertification

  • Where is Tropical Desert ?Between 20 to 30 N and S.Subtropical High Pressure Zone.Sinking Limb of The Hadley Cell.Usually in Western Part of Continents.

  • Examples of Tropical DesertLow Developed Countries:Sahara DesertHigh Developed Countries:Southern CaliforniaWest Australian

  • Opportunities And Constraints

    AtmosphereHydrosphereLithosphere

  • Atmosphere1.High insolation input High temperature in daytime Large diurnal range of temperature

    2.Low annual rainfall, less than 250mm Rainfall unreliable, variable and localized Low relative humidity

  • Opportunities And ConstraintsHigh temperature --- Long growing season favors plant growthToo high for people to live

    High insolation input--- Solar energy

  • HydrosphereLow annual rainfallSmall base flowLow discharge (except exotic rivers)Low water tableBut flash flood may happen

  • Opportunities And ConstraintsFarming and navigation are difficult.Oasis Farming is possible where water table is stable.Nomadic herding is possible.

  • LithosphereSoils are salineCoarse texturedAlkaline (over pH 9)Little leaching and CEC

  • Opportunities And ConstraintsRich in mineral resourcese.g. oil, salt.Large area for settlementUnfavorable for farmingSand Storm

  • Human activities in TD

  • 1.Nomadic herdingpeople move with cattle and sheep from place to place for water and pasture.

  • 2.Arable farmingIt is the practice of extensive agriculture to produce crops without irrigation in regions with low rainfall.

  • 3.MiningOil, rock salt, etc are mined

  • 4.Scientific researche.g. nuclear testing due to sparse population and space there

  • Case Study Dubai

  • Where is Dubai ?Coast of the United Arab Emirates. Lies within the Arabian Desert.Sandy desert surrounding the city.

  • Economic Activities in DubaiBefore 1970s, agriculture was the major economic activities.However the discover of oil made the rapid development of oil industry.In the past 20 years, the government is developing the city into financial city. Oil industry accounts only 5% of the GDP.

  • Desertificationthe degradation of land in arid, semi arid and dry sub-humid areas

    resulting from various climatic variations, but primarily human activities

    increase in population demand for land ( for growing crops and grazing animals)

  • CausesHuman development deforestation (for constructing buildings, extracting resources) population growth overcultivationsoil fertility soil left exposedOvergrazing compact soil together reduce percolation rate erosion

    Climatic factors rainfall vegetation cover soil exposed to wind erosion

  • 1930s United Statespart of the Great Plains Dust Bowl Overgrazing Drought Since 1949Chinapopulation of rural area Overgrazing

  • Soil becomes less productive.Vegetation becomes damaged.Food production is affected.

  • Sustainable developmentAfforestationConstruction of water channels to supply water.Control the population, so demand of land can be reduced.