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HOT DESERTS - DESERTIFICATION (Management (Water Management (Drip…
HOT DESERTS - DESERTIFICATION
Degradation of land so that it becomes more desert-like - it becomes drier and less productive.
A third of the world's land surface is at risk of desertification, particularly at the margins of deserts
Soil erosion
Key part of desertification
Exposed soil (not covered by plants) is easily removed by wind or water
Nutrients in the soil (e.g. from fallen leavesand dead plants) are lost, making soil unproductive
Eventually ground becomes:
Dusty
Stony
Bare rock
Sandy
Main cause - Climate Change
Rainfall
Reduce rainfall in already quite dry areas
Less water available for plant growth → so plants die
Soil is easily eroded, as without plants there are no roots to hold together the soil
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Temperatures
Global temp. expected to increase
High temp. → more water evaporation from land and plants
Soil drier from water loss and makes plants die → no roots to hold soil together → soil erosion
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Main Cause - Human Activities
Removal of fuel wood
Many people in arid (dry) areas rely on wood for fuel for cooking
Soil exposed from tree removal so easily eroded
Overgrazing
Too many cattle or sheep eat plants faster than they can re-grow
More soil erosion no plant roots to hold soil together
Trampling by animals also erodes soil
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Over-cultivation
If crops planted in the same area continually/regularly, all the nutrients get used up
So plants can no longer be grown there, without plants more soil erosion
Population growth
Pressure on the land
More deforestation (for firewood
More overgrazing
More over-cultivation
Management
Desertification can be reduced
Water Management
Growing crops that don't need much water
e.g. millet, sorghum or olives
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Reduces water use
Drip irrigation
Instead of surface irrigation
Soil isn't eroded by lots of water being added all in one go
Tree Planting
Planted as windbreaks to protect soil from wind erosion
Used to stabilise the sand to prevent the desert from encroaching on farm land
Trees among the crops → protects crops (and soil) by providing shade → reduces temperatures and evaporation rates
Soil Management
Leaving areas of land to rest in between grazing or planting lets them recover their nutrients
Rotating crops that use different nutrients from the soil mean that the same nutrients don't keep being removed
Compost can be used to add extra nutrients to soil
Appropriate technology
Cheap, sustainable and easily available amaterials that are easy for local people to maintain
e.g. sand fence (barrieres to trap windblown sand) or terraces ca be constructed to stabilise the soil and reduce erosion
Rate of deforestation reduced by solar cookers, which use sun's energy to heat food. Cheap and easy to make, and don't require fuel wood to work