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ContentContent
• Environmental Characteristics
• Opportunity and Constraints
• Human Activities in Tropical Desert
• Desertification
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 Desert
Low Developed Countries: Sahara Desert High Developed Countries: Southern California West Australian
Opportunities And Constraints
AtmosphereHydrosphereLithosphere
Atmosphere
1.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 Constraints
High temperature ---
Long growing season favors plant growth
Too high for people to live
High insolation input--- Solar energy
Hydrosphere
Low annual rainfall Small base flow Low discharge (except exotic rivers) Low water table But flash flood may happen
Opportunities And Constraints
Farming and navigation are difficult. Oasis Farming is possible where water table
is stable. Nomadic herding is possible.
LithosphereLithosphere Soils are salineSoils are saline Coarse texturedCoarse textured Alkaline (over pH 9)Alkaline (over pH 9) Little leaching and CECLittle leaching and CEC
Opportunities And Opportunities And ConstraintsConstraints
Rich in mineral resourcesRich in mineral resources
e.g. oil, salt.e.g. oil, salt. Large area for settlementLarge area for settlement Unfavorable for farmingUnfavorable for farming Sand StormSand Storm
Human activities in TD
1.Nomadic herding
people move with cattle and sheep from place to place for water and pasture.
2.Arable farming
It is the practice of extensive agriculture to produce crops without irrigation in regions with low rainfall.
3.Mining
Oil, rock salt, etc are mined
4.Scientific research
e.g. nuclear testing due to sparse population and space there
Case Study – Dubai Case Study – Dubai 杜拜杜拜
Where is Dubai ?Where is Dubai ?
Coast of the United Arab Emirates. Lies within the Arabian Desert. Sandy desert surrounding the city.
Economic Activities in DubaiEconomic Activities in Dubai
Before 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.
Desertification
‧the 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)
Causes
Human development → deforestation (for constructing buildings, extracting resources…)
→ population growth overcultivationsoil fertility ↓soil left exposed
Overgrazing compact soil together → reduce percolation rate → erosion ↑
Climatic factors rainfall ↓ vegetation cover ↓ soil exposed to wind erosion↑
1930s United States part of the Great Plains Dust Bowl →Overgrazing
→Drought
Since 1949‧China
‧population of rural area ↑ Overgrazing
• Soil becomes less productive.• Vegetation becomes damaged.• Food production is affected.
• Sustainable development• Afforestation• Construction of water channels to
supply water.• Control the population, so demand of
land can be reduced.