AS Geography: Arid Environments FLASHCARDS NEEDED

Climate: 

Influenced by...

Temperature: Huge solar radiation during day, terrestrial radiation escapes by night - becoming cool - Large diurnal range

Precipitation: aridity can be cause by...

• latititude (Hadley cells)
• offshore winds (winds blowing towards the sea)
• relief (mountains blocking way)

therefore Little plant cover ground is exposed

Winds: 

Cross winds (such as NE Trade Winds) causing huge sandstorms

Insolation Weathering: Also known as 'Onion-skin' weathering

• Layers of rock expand & contract due to the large diurnal range in temperature
• Granular disintigration can occur when light and dark minerals in rock, such as granite, heat and cools at diffrent rates

Wetting & drying:

• Similair process as insolation weathering, but with flash-flood water instead being heated up and cooled

Crystal Growth:

• High temperatures causes saline groundwater to the surface and water then evaporates. Crystals grow between pores in rocks and expand. Particularly occur on coastal deserts

Main Feature - Pedestal Rock:

• Hard rock cap with soft rock being eroded away
• Cyrstal growth forming case-hardened layer that protects top pedestal

Wind - Deflation: 

Removal, by wind, of uncolnsolidated material - creating depression hollows

Abrasion:

Wind blowing against the rock like sandpaper

Attrition:

Sand particuls hitting each other, becoming smaller

Main Feature - Yardangs: Wind aroding hard rock, creating smooth, board side in direction of wind

Water - 

Ephemeral River: Temporary river + loose sediment = huge loss of sediment & rock abrasion

Main Feature - Wadis: Temporary river which often braids into smaller channels & deposits

Plant: Prickly Pear Cactus

Is a Xerophyte, has many diffrent mechanisms to survive

1.) Is a succulent, so stores its water in leaves/stems for when its needed

2.) Opens its stoma to absorb carbon at night, to avoid transpiration

3.) Asexual reproduction as opposed to seed-based, which saves precious energy but they can still do thisto maximise survival 

4.) Waxy leaves or cuticles which act like waterproofing, protecting from water loss

5.) Have a crassulacean acid metabolism so they can do photosynthesis when stoma are closed

Arid animal: Camel

1.) large, flat feet to spread their weight on the sand

2.) thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss

3.) a large surface area to volume ratio to maximise heat loss

4.) the ability to go for a long time without water -  store food in their humps, but they lose very little through urination and sweating

5.) the ability to tolerate body temperatures up to 42°C

6.) slit-like nostrils and two rows of eyelashes to help keep sand out.

7.) Thick lips to eat thorny plants

Case Study: Mojave & Sonoran Desert

Ecosystems = Flora, Fauna, Soils 

Physical:

• Rainfall - Too muc rain = flash fooding. Too little = drought
• Dust storms - Can damage fragile plants such as Creosote bushes
• Plants, such as the Saguaro Cactus, are vunerable to lighting strikes. Which, in turn, could cause fires
• Soils - Relatively thin & infertile, making the growth process for plants even worse
• Often, cold winters & frosts  can affect plants which are prepared for heat, not cold

Human:

• Non native species - Donkeys, which excaped captivety, roam wild and affect native species such as the Bighorn Sheep by competing for food. Bufflegrass was introduced to improve pasture, it spread, causing forest fire risk; killing off 20% of Saguaro Cactus in 1994

Human (Continued):

Urbanisation - Displacement, fenced of migration routes, Pronghorn (travel great distances) are blocked from food & water 

Water extraction - Cities like Vegas take water from a region with barely any water of its own, decline in Cottonwood trees, a species which grows along the river banks

Soils ability to hold water and air hindered by vehicles driving over them (Eg. Military Installments)

Desert Tortoise loss of habitat & killed by grazing animals; also targeted by collectors

Case Study: Egypt - Pyramids, Valley of Kings, Sharm-El-Sheikh

Opportunities:

• Egypt derives 45% of its income from tourism - can be used to improve infrastructure
• Money can be used to resotre heritage - Ancient tombs in valley of kings
• Preserves the cultures through money raised through shows and events 
• Creates direct employment & indirect imployment; eg. fisherman

Challenges:

• Need money for tourism, tourists cause damage to sites and break rules (eg, humidity in tombs damaging the artwork + scaling the pyramids) - vicious cycle
• Jobs often low paid & un skilled and are often exploited by TNC's which majority of money reaching them, not the country
• Over realience: Seasonal + political instability such as terroist attack in red sea caused decline in tourism to Sharm-El-Sheikh
• Psuedo events which are often held by people not related to the local culture + traditional necklaces ect are often manufactured
• Untreated sewage pumped into the oceans - In Sharm-El-Sheikh, local coral reefs have been polluted
• Tourists casuing offence to majority muslim population through exposing clothes and behaviour

Case Study: Niger Agriculture

Niger...

is a poor semi-air country, $900 GDP + life expectancy of 44

Desertification is leading to lack of food to feed the populance

Planting Pits ('Za') - Holes with seeds placed in to collect runoff and rainwater + manure

Manuring - Famers corral their animals in fields to fertilise it naturally, as chemicals are expensive

Intercropping - Grasses & shrubs planted between crops to act as windbreak

Bunds - Low stone walls built on edge of fields to retain earth and hold back water

Case Study: Uluru. Australia

• Involving local people in managment; eg Aborgines as Park Rangers, meaning they dont have to move hundreds of miles to find work
• Education by Aboriginal lecturers on how sacred the ground is to them
• Camping ground, hotels and shops moved 10km away with that former land being rehabilitated + new facilities are designed with low rising architecture and desert colours and solar panels 
• Roads have been improved and official walking tracks constructed to limit people wandering onto precious wildlife etc