AQA GCSE Geography - Hot Deserts

Describe the location of hot deserts?

- near the tropics of Cancer and Capricorn

- 30 degrees north and south of the equator

- in dry, continental interiors away from the coast

Describe the climate of hot deserts?

- little rainfall (<250mm annually)

- extreme temperatures (50 degrees at day and below 0 degrees at night)

Describe the soil of hot deserts?

- Sandy and shallow with a coarse gravelly texture

- Salty (evaporation draws salts to the surface)

- Thin with a white crust due to the infrequent rainfall

- infertile (not much leaf fall)

Name 4 plant adaptations?

- tap roots

- small and waxy leaves

- spines

- large, fleshy stems

Describe how tap roots are useful adaptations?

Tap roots are long roots (7-10 metres) that reach deep underground to access water supplies

Describe how small and waxy leaves are useful adaptations?

small and waxy leaves ensure less water is lost through transpiration

Describe how spines are useful adaptations?

Spines lose a lot less water than leaves through transpiration, furthermore they help protect the plant and its water supplies from animals. e.g. cacti

Describe how large, fleshy stems are useful adaptations?

Large, fleshy stems allow for lots of water to be stores. e.g. succulents

Describe the 3 adaptations of the Saguaro Cacti?

- thick, fleshy stems to store water

- spines for protection and efficient in water loss

- widespread root systems to access water supplies

Why do animals need to adapt in order to survive in hot deserts?

Hot deserts provide harsh conditions for animals, so they need to adapt both physically and behaviourally in order to survive. They must avoid heat, find water, retain water and survive.

Describe the 5 adaptations of a camel?

- long eyelashes to keep dust out

- light in colour to reflect heat

- tough mouth for eating thorny plants

- large padded feet to stop sinking

- stores fat in humps

Describe the 2 adaptations of the Jerboa mouse?

- nocturnal so it minimises its energy use

- huge ears to keep cool

Biodiversity

the variety of life in the world or in a particular habitat or ecosystem

Describe the biodiversity in a hot desert?

- the harsh climate means very little biodiversity in general

- highest levels of biodiversity are in areas with water (so around temporary ponds and rivers, or along desert margins)

Case study - The Western Desert

- Located in south west of America

- Over 200,000 square km

- Extends across several US states e.g. Arizona, California

- Comprises of Sonoran, Mojave, Chihuahuan desert.

- Low population density with majority of inhabitants living in large cities

What are the 4 development opportunities in the Western desert?

1. Farming

2. Mining - mineral extraction

3. Tourism

4. Energy

Explore the development opportunity of Farming?

- Most farming is large scale

- Farmers allocated 80% of Colorados rivers water through agri which just makes up 10% of the economy

- Canals are sources of water for irrigation

Explore the development opportunity of Tourism?

Jobs are created and there is the multiplier effect, but the desert is quite inaccessible and this creates problems like poor infrastructure.

- Las Vegas attracts 31 million a year

- Number of national parks

Explore the development opportunity of Mining?

The resources can be used or sold to make a huge benefit. However, mining has dangerous working conditions, it scars the landscape and uses up the scarce water resources left.

- Copper mined in Sonoran desert

- Uranium mined in Grand Canyon, used for nuclear power plants

Explore the development opportunity of energy?

Renewable energy resources are being used (this helps with climate change and deforestation), however things like wind turbines are an eyesore and can be hazardous

- Solar panels in Sonoran desert

- Oil extraction in Arizona providing jobs

What are the 3 challenges of development in the Western Desert?

1. Inaccessibility - the desert covers 200,000 sq km, however most of it is inaccessible. If transport breaks down extreme heat can be dangerous

2. Water supply - limited supply. Rainfall is 55mm a year. Population growth increases stress and pressure on water supply

3. Extreme temperatures - make it difficult for working conditions: to farm, for development, for tourist guides and even the tourists

Define desertification

the processes by which land becomes drier or degraded as a result of climate change, human activities or both. Areas most vulnerable to desertification are generally on the fringe of already existing deserts

What are the 6 causes of desertification?

1. Climate change- Less rainfall - Vegetation dies

2. Population growth- More water needed leads to over farming

3. Removal of fuel wood (deforestation)- protects it from wind and rain

4. Overgrazing- Strips the land of plant cover leading to wind and rain erosion

5. Over cultivation- Uses up nutrients plants fail to grow and lead to wind and rain erosion

6. Soil erosion- topsoil, most fertile is blown away. Soil is less productive.

Describe the 4 strategies to manage desertification?

1. Water management - grow drought tolerant crops/ earth dams/ use drip irrigation systems

2. Tree planting - protects the soil/ provides shade

3. Soil management - rotating crops/adding compost

4. Appropriate technology - use of cheap, sustainable and easily available available materials that are easy for local people to maintain as well

Define overgrazing

The removal of plant matter by livestock, exposing soil to erosion. Livestock are heavy animals that compress the soils with their hooves.

Define over cultivation

the excessive use of farmland to the point where productivity falls due to soil exhaustion - plants