Deserts Flashcards
Spain- Causes of risk desertification
climate change:
-average temp has risen by 1.5 degrees = increased risk of forest fires
-decrease in rainfall specifically in southern Spain
-between 1995- 2015, volume of fresh water in Spain fell by 20% = less groundwater recharged = less plants and roots = more soil erosion
Agriculture:
-80 million tones of topsoil is lost each year due to intensive cultivation of olive trees in Andalusia
- illegal boreholes made by farmers to supply crops with water = uses 70% of groundwater depleted
-intensive irrigation induced due to Almeria in Andalusia being driest area in Europe and contributes $1.5 billion to economy
-also Spain is Europe’s largest export of strawberries which 95% are grown in Andalusia
Development
-huge increase in tourism in Southern Spain in the last 50 years = 180,000 holiday homes were built along Spanish coast in 2004 = increasing strain on water supplies due to more demand for water for swimming pools, water parks and irrigation of golf courses
Spain- Impacts of the risk of desertification
Environmental:
-exploitation of ground water= loss of habitats e.g 150,000 ha of marshland surrounding Donana National Park has been lost since 19000, most drained by farming
Social :
-as groundwater becomes salinised = no longer suitable for drinking or irrigation = effect on farming and farmers livelihood = food and water insecurity
-conflict over water = black market for water created supplied from illegal boreholes = 40% of land in Murcia is illegally irrigated
Economic
-Brussels and EU threatening Spain with financial sanctions over Andalusia’s plan to allow more irrigation
-salinised water unusable for farming and agriculture which contributes $1.5 billion to economy
-Irreversible damage has been done to more than 3.5 million hectares of crops
Spain - solutions
success:
National Hydrological Plan 2001:
-drip irrigation has reduced amount of water wasted
-desalination plants built to provide fresh water from the sea
-areas at high risk of wildfires have been identified= helps draw up defense plans, some areas are reforested after wildfires or deforestation = area of forested land in Spain increased from 27% to 37% 1990-2015
-official water trading scheme has been set up = allows farmers to buy water reducing illegal exploitation of aquifers
failures:
-desalination plant in Torrevieja cost $300 million to build and isn’t running due to lack of buyers for the water
-government proposed various schemes to transfer water from plentifully supplied areas to very little supplied = people protested against transfer from Ebro River to Southeast Spain due to damage to wetland ecosystems it would cause
The Sahel- causes of risk of desertification
climate change:
-30% decrease in rainfall in 1970s and 80s due to oceans warming and air pollution from human activity
agriculture:
-removal of large parts of the natural vegetation, including shrubs, grasses, and trees, and replacing them with crops and grass types that were suitable for (short-term) grazing.
-deforestation= From 2000 to 2020, Sahel experienced a net change of 48 ha (32%) in tree cover
population increase:
-rate of population increase (3%) is greater than the increase in food production (2%) = pressure on land and agriculture
The Sahel- impacts of risk of desertification
environmental:
-37% forest cover was reduced in West Africa between 1975 and 2013
-The Sahel ecological zone has shifted 25-35km southward resulting in biodiversity loss and conversion of arable land to sand dunes = migration of people and species
social:
-food and water insecurity in Burkina Faso (2.5 million food insecure people
-water supply - lake chad (largest lake in chad) has shrunken by 95% since the 1960s due to pop growth and unsustainable irrigation = water insecurity and economic effects on farming
economic:
-increased temps and land degradation = reduces crop yields = economic downturn and risk of famine as 70% of labour force in Burkina Faso is in agriculture
-Mali’s lake Faguibine drying = caused 200,000 farmers and fishermen to abandon their livelihoods
The Sahel - solutions
Success:
-Burkina Faso’s Magic stone lines increase surface resistivity slowing wind causing less soil erosion and adjust microclimates due to shade reducing evaporation and helps store water
= crop yield since increased by 50%
30,000 km and low cost
issues:
-hard to scale up, works more on a smaller scale
Great green wall- Africa
-1/5 of degraded land restored (20 million hectares)
-42% reduction in chronic infant malnutrition = fruit resources from trees, baobab leaves
issues
-depleting groundwater = less soil moisture
-over 50% of seedlings lost within a decade because soil conditions weren’t optimal for chosen species
The Badlands
-Rills and gullies are formed by fluvial erosion on hillsides. Rills are smaller
-Badlands in southwestern South Dakota- American national park 250,000 acres large
-formed by deposition and erosion
-erode at the rate of 1 inch per year = in around 500,000 they will be completely gone
-on average badlands see less than 20 inches of rain per year= harsh environments
Describe the Atacama désert
-hyper-arid désert due to
-dominated by high pressure (falling limb of Hadley cells), 30 degrees Latitude
-continentality : prevailing winds from east= air travels far before desert= drying out
-relief: air from east has to rise over the Andes and so dries before it passes over, Chilean coast range
-cold ocean currents: Peru current flows along the coast and it is cold = limited thermal capacity
Describe the Sahara desert
-23 degrees north latitude
-Central Sahara upnto 2000km from body of water
-Atlas mauntains separating Sahara desert from the Mediterranean sea
-cold canary currents
describe the Kalahari desert
-25 degrees lattitude south
-Koronnaberg Mountains act as a rainfall catchment
-cold ocean currents on the west
episodic flood in imlil
huge quantities, but rarely occur
E.g. imlil Morocco
1995 70mm rain in 3 hours
6m depth of water, 150 died
