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DESERTS Flashcards

1
Q

What is a desert?

A

High rate of evapotranspiration which exceeds precipitation

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2
Q

Hyper-arid is..

A

<50mm a year

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3
Q

hammada

A

Barren and rocky ground

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4
Q

reg

A

gravel/pebble plain between Hammada and erg

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5
Q

erg

A

Mostly sand dunes

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6
Q

What factors affect soil development

A

Climate, topography, time, vegetation and parent material

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7
Q

Desert soils are called…

A

aridisols

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8
Q

aridisols are..

A

Infertile and thin because of a lack of rotting material and vegetation nut mineral rich because they do not get washed out by the rain

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9
Q

xerophytes

A

Plants which adapt to desert conditions

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10
Q

Properties of xerophytes

A

Separately distributed- no sharing
Long roots up to 15m to reach sources below the ground
Small way or thorny leaves to protect from predators and reduce transpiration

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11
Q

What are succulents

A

Can expand to store water after an event of rainfall - cacti

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12
Q

4 atmospheric processes

A

Continentality
Rainshadow effect
Cold ocean currents
High pressure

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13
Q

High pressure

A

Hot wet air rises from the equator through convection
As the air heads to the poles it rains and becomes dry and dense creating high pressure on the ground (Anticyclone)
A lack of clouds also increases evapotranspiration

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14
Q

Continentality

A

Lack of impact from oceans

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15
Q

Rainshadow effect

A

Where rain is dumped on the windward side of the mountain cause it condenses on the mountain
Then pressure on the leeward side sinks and warms up the dry air creating a desert

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16
Q

Cold ocean currents

A

Cold seas create cold air which is denser than warm air and sinks to the ground
This results in high atmospheric pressure where the cold air from the ocean meets the warm dry air
This creates cold fog which sinks instead of rising and raining

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17
Q

Weathering process’s

A

Chemical or biological weathering – not common in the desert due to an absence or vegetation and rotting materials

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18
Q

Mechanical weathering - insulation weathering

A

Expansion and contraction of rocks surface layer due to extreme temp fluctuations

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19
Q

Wind transportation in deserts

A

Traction = Surface Creep
Saltation - rocks are hit forward by smaller particles
Suspension

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20
Q

Exogenous river

A

The source in outside the desert region

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21
Q

Endoreic rivers

A

Terminate in deserts into a lake or a sea

22
Q

Ephermal rivers

A

Flow seasonally or temporarily

23
Q

Landlords associated with wind

A

Yardage
zeugen
barchans
seifs

24
Q

Landlords associated with water

A 
wadis
Canyon
Mesa
Buttes
Alluvial fan
Inselbergs
badlands
25
Yardang
Parallel elongated ridges parallel to the prevailing wind formed by wind abrasion
26
barchan
Crescent shaped sanding - horns are in the direction of the dominant wind direction
27
seifs
Longitudinal elongated sand dunes which form parallel to prevailing wind
28
wadis
Steep dried out river valleys, a large Wadis is a canyon, and alluvial fan can often be found at the bottom
29
Mesa
Large risen plateau formed by river erosion
30
Buttes
Same as mesa but smaller pinnacles of rock
31
inselberg
more rounded relic landforms that form in rocks like granite where there is an absence of layering, therefore the surface is much smoother
32
Badlands
– a semi-arid landscape intensely carved by heavy rainstorms and impermeable rocks
33
How much of the world is affected by desertification according to the UN
A third
34
Human cause of desertification
Over- cultivation – intense farming can reduce soil fertility and its capacity to retain moisture Over-grazing – Grassland has a sustainable carrying capacity for animals and vegetation and soils deteriorate Over-irrigation - an excess of water can create salinization and form an impermeable and infertile salty crust Tourism- road building, deforestation etc. Over population Deforestation
35
Location and things happening in the sahel
Edge of Sahara Belt of 1000km Poorest countries on earth Border conflicts, kidnapping, movement of arms and drugs, oil gas and gold reserves Since 1960 the Sahara expands south 2-5 km a year
36
Since what year has the share expanded how much south
Since 1960 the Sahara expands south 2-5 km a year
37
Cause of desertification in the sahel
Population increase Firewood overgrazing drought
38
How many people like in the sahel and doubling time
260 million | 20 year doubling time
39
Population increase in the sahel % and % of increase in food production
3% a year and food production is at 2%, therefore there is additional pressure for over-farming
40
How is the sahel being managed
Fences and trees to reduce effects of wind erosion Promoting solar ovens to reduce the demand for firewood Green-wall project in Senegal with a 15km tree belt The Eden reforestation project charity- over 1 million trees are being planted in Ethiopia and Sudan
41
States of the Mojave
Cali, Nevada, Utah, Arizona - home to death valley, hottest place in the world atm
42
Issues in the mojave
``` Urban expansion Water supply Military training Conservation Waste management Tourism ```
43
Mojave- Urban expansion
Population expected to triple in next 20 year- retirement and big cities like las vegas Shortages in water and land - conflict
44
Mojave- water supply
California Aqueduct transport water from the Nevada mountains to stop strain on the Colorado river
45
Mojave- military training
DoD work with the BLM to conserve biological resources
46
Mojave- conservation
- $93 million was spent within 10 years to successfully bring the Mojave desert tortoise from he brink of extinction
47
Mojave- Waste management
2009 a landfill site near the Joshua Tree NP was halted
48
Mojave- tourism
Designated off road areas prevent off-road vehicles from damaging vulnerable areas
49
Difference between the sahel and Mojave - region
sahel is an international region where it is hard to come to agreements
50
Difference between the sahel and Mojave - economy
sahels surrounding countries are amongst the poorest in the world therefore more money is spent on development not desert management whereas the USA is the largest economy in the world
51
Difference between the sahel and Mojave - political
Political instability means there few links between countries and money is often spent on weapons and defence whereas The USA has well-respected environmental groups with a strong government
52
Difference between the sahel and Mojave - population per rainfall
Rainfall seems to be becoming more and more un reliable with a rising population whereas in the US there is a stable population so desertification kept under control

Geography AS (6 decks)

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