The degradation of land in arid areas by which fertile land becomes desert like
- 75 billion tonnes of soil eroded annually
Human Causes:
- Overgrazing
- Reduces vegetation > soil erosion (due to lack of plant roots)
- Trampling by animals > compressed & breaks down structure of soil > erosion more likely
- Overcultivation:
- Reduces soil productivity > without plants > soil is easily eroded
- Irrigation:
- Depletes surface water and may involve unsustainable pumping of aquifers. As water levels are lowered, water availability for plants decreases, leading to soil erosion.
- Surface irrigation= large amounts of water added to soil quickly, washing topsoil away
- Too much water to irrigate crops = excess sink into soil and raise groundwater levels.
- If aquifer saline, may bring high conc. of salt close to the surface, increasing salinity
Impacts of Desertification
- Landscapes: The ground surface becomes more prone to erosion because:
- Vegetation slows wind speed, so reducing vegetation cover increases wind speed.
- Moisture evaporates from soil more quickly when it isn’t sheltered by plants, so it dries out.
- Plant roots that help to bind the sediment together are lost.
- Higher wind speeds = more mobile sediment can also = more sand to be blown into an area
- Ecosystems:
- Land less fertile, less plant life > reduces amount of organic matter that is put into the soil > further reducing vegetation growth. Less vegetation > less animal supported > – biodiversity
- Distribution of species. Plant & animal may die out or migrate to less degraded areas.
- Releases carbon stored in soil into atmosphere > climate change > widespread impact
- Populations:
- Reduction in the fertility of land > decline in agricultural productivity= migrate from the area >
- Often people migrate from rural to urban areas > may lead to overcrowding.
- Human health in other ways, e.g. dust from soil erosion can = respiratory diseases
- Reduction in the fertility of land > decline in agricultural productivity= migrate from the area >
Future Climate Change Impact:
- Semi-arid areas to become hotter and drier- More extreme weather events, such as heat waves
- Global temperatures are expected to rise up to 6 degrees between 2015 and 2100.
Future for Locals: uncertainty surround the potential strategies
- Depends mitigation of impacts of and prevent more land from being degraded.
Futures for Desertification:
- Desertification may continue:
- If action isn’t taken to reduce desertification, or if strategies aren’t funded or managed
- Decrease in agricultural yields > increase malnutrition and famine = hinder development
- May be conflict within and between countries as food and water becomes more scarce
- Humans may stop or reverse desertification:
- LOCAL: People plant vegetation to bind the soil and act as windbreaks. Farmers can carry out crop rotation to allow the soil to recover, and improve irrigation systems.
- GLOBAL: responses to climate change could have a major effect. However, this would require major commitment and cooperation around the globe.
- Humans may reduce the impacts of desertification:
- Local populations may change their lifestyles in order to adapt and reduce its impacts.
- g. local farmers could change their farming methods E.g. keeping small livestock such as goats and chickens, which would be less affected by desertification than crops
- Improvements in agricultural technology = increase food they produce per hectare