🏜️ Physical: Hot Deserts

Question 1

What is mineral extraction?

Answer 1

The removal of solid material resources from the earth such as ores, coal, oil and precious stones.

Question 2

Define hot deserts.

Answer 2

Areas of the world that have high average temperatures and very low precipitation.

Question 3

What is desertification?

Answer 3

The process by which land becomes drier and degraded, as a result of climate change or human activities or both.

Question 4

What is biodiversity?

Answer 4

The variety of life in the world or a particular habitat.

Question 5

What is overgrazing?

Answer 5

Grazing too many livestock for too long on land, so it’s unable to recover its vegetation.

Question 6

What is over-cultivation?

Answer 6

Exhausting soil by over-cropping the land.

Question 7

What is appropriate technology?

Answer 7

Technology suited to the needs of the local people that combines cheap materials and is environmentally friendly.

Question 8

What is soil erosion?

Answer 8

The removal of topsoil faster than it can be replaced, due to natural, animal and human activity. Topsoil is the top layer of soil and is the most fertile because it contains the most organic, nutrient rich materials.

Question 9

What is aridity?

Answer 9

The state or quality of being extremely dry.

Question 10

What is Diurnal Temperature Range?

Answer 10

The difference between the maximum and minimum temps in that day.

Question 11

What is a xerophyte?

Answer 11

A species of plant that has adaptations to survive in an environment with little water e.g. cacti

Question 12

What is carrying capacity?

Answer 12

The maximum number of people an area of land can support before environmental damage.

Question 13

What is the desert fringe?

Answer 13

Boarders of hot deserts. They support greater biodiversity and large plants. Semi-deserts.

Question 14

What is the definition of a desert?

Answer 14

An area receiving less than 250mm of rainfall resulting in extreme aridity.

Question 15

What are the physical characteristics of hot deserts?

Answer 15

• Extreme aridity (250mm< rainfall)
• Lack of biodiversity
• Barren (sparse vegetation)
• Rocky + sandy
• Above 40° during the day + sometimes cold during the night

Question 16

Describe the location of deserts.

Answer 16

Deserts are found between 20° + 30° North and South of the equator (at the tropics)

Question 17

Explain why deserts are where they are and how they’re formed.

Answer 17

• Insolation concentrates strongest on the equator making it hottest
• Low air pressure at the equator warms air and then clouds form with heavy rainfall when risen
• The air rises until it is eventually dry and heads N+S due to the Coriolis effect
• The cold, dense dry air then sinks forming deserts

Question 18

Describe the soils found in the desert.

Answer 18

Sandy and rocky, typically about 1mm deep. They lack organic material and may have white powder on the top where salts are drawn to the surface by evaporation.

Question 19

Why do deserts get very hot in the day and cold at night?

Answer 19

Lack of clouds means that temperatures during the day are very hot, and at night the lack of clouds means that there is nothing to keep the heat in.

Question 20

What are some examples of interdependence in hot deserts

Answer 20

• Plants + Soil: plants tie soil together preventing soil erosion, they also shade from sun and evaporation and help soil retain water. Soil gives plants extra nutrients through dead vegetation + fixing chemicals from the air into soil
• Animals + Plants: primary consumers feed on the producers, giving them energy and animals can disperse the producer’s seeds
• Food Webs

Question 21

What are three issues related to biodiversity?

Answer 21

Dry conditions, high temperatures and competition for nutrients.

Question 22

What are desert yellow daisies and how have they adapted to the challenges of hot deserts?

Answer 22

A species of flower with small, linear hairy leaves to reduce loss of water through evapotranspiration. They also have a waxy resin also to reduce water loss.

Question 23

What are prickly pear cacti and how have they adapted to the challenges of hot deserts?

Answer 23

A species of cacti with roots spread out over a large, shallow area under the soil to maximise nutrient absorption and make the most out of sudden rainfall.

Question 24

What are saguaro cacti and how have they adapted to the challenges of hot deserts?

Answer 24

A species of cacti that only grows in the Sonoran desert that grows very slowly to conserve energy, can store up to 9 tonnes of water, body is made of vertical pleats that expand for greater water storage and they can lose 82% of its water before dying of dehydration.

Question 25

What are fennec foxes and how have they adapted to the challenges of hot deserts?

Answer 25

- A small species of fox that have large ears, usually 6 inches long to help dissipate excess body heat through capillaries. - Their kidneys are adapted to restrict water loss and they receive moisture from their food. -Their thick fur helps insulate them at cold nights. - Their sandy fur helps camouflage - They have thick fur on the soles of their feet which gives them excellent traction on the loose sand and insulates against the hot sand

Question 26

What are peringuey's adders and how have they adapted to the challenges of hot deserts?

Answer 26

They are a species of adder that moves sideways and means that 50% of their body is in contact with the hot sand.

Question 27

What are kangaroo rats and how have they adapted to the challenges of hot deserts?

Answer 27

- They are a species of rat that don't sweat and have oily skin to reduce water loss. - Produce little urine - Live in burrows during the day - Don't need to drink, get water from food

Question 28

What are camels and how have they adapted to the challenges of hot deserts?

Answer 28

- A species of mammal that can go a week or more without water, and they can last for several months without food, can drink up to 32 gallons in one drinking session - They store fat in hump that can be metabolised for energy - A healthy body temperature changes from 34° - 42° - Their huge feet help them walk on sand easily - They have thick lips so they can eat prickly desert plants without any pain - They have hair in and outside if their ears to keep sand out

Question 29

What are the opportunities in the Western Desert, USA?

Answer 29

- Tourism - Farming - Mineral Extraction - Energy Generation

Question 30

Explain how tourism is a development opportunity.

Answer 30

- There are multiple national parks like the Grand Canyon + Joshua Tree NP - The Colorado museum shows the heritage and culture of native Americans - Lake Mead + Powell offer sailing, power, water skiing and fishing - Las Vegas gets 37mil visitors per years - Tourism has become the western Desert's most important source of income

Question 31

Explain how farming is a development opportunity.

Answer 31

- Farming is available for more inhospitable areas of the Western Desert - Coachella valley produces lush crops of vegetables, lemons, peppers + grapes - They have a huge wine industry - Perfect conditions for growth: aquifers and canals - Farmers are allocated 80% of Colorado water even though they make up just 10% of the economy

Question 32

Explain how mineral extraction is a development opportunity.

Answer 32

- Copper mining has taken place for centuries in the Sonoran desert - Western Desert is rich in copper, uranium, lead, zinc and coal - There's a copper mine in Arizona called the Ajo copper mine

Question 33

Explain how energy generation is a development opportunity.

Answer 33

- Strong insolation in deserts brings huge solar energy - Sonoran solar project required 360 workers to build it - Hoover dam employed 5k people - Sonoran solar project produces energy for 100k homes

Question 34

What are the challenges in the Western Desert, USA?

Answer 34

- Water supply - Climate - Transport and accessibility - Climate change

Question 35

Explain how water supply is a development challenge.

Answer 35

- Colorado river has low flow between September and April - Temperatures are due to rise and therefore more water evaporation - Silts + sands get trapped behind the Glen Canyon Dam and Hoover dam which makes the water that leaves colder and changes the river ecosystem, losing many species

Question 36

Explain how transport and accessibility is a development challenge.

Answer 36

- In 2015 an elderly man died due to dehydration and lack of roads - Low population density of less than 1 person per square km, so there is a lack of surfaced roads

Question 37

Explain how climate is a development challenge.

Answer 37

- Average temperature of 27° and can reach 50° - Manual labour outside is extremely difficult due to the intensive heats - High temperatures lead to water loss and evaporation

Question 38

Explain how climate change is a development challenge.

Answer 38

- In 2014, Lake Mead reached a record low level - By 2100, average annual temps could be 5° higher - The western desert is projected to warm faster than the rest of the world - Population growth and temperature increase means an even greater water security is expected in future

Question 39

Why is vegetation so vital in dry areas?

Answer 39

It protects the soil from drying out and desertification

Question 40

What are the causes of desertification?

Answer 40

- Climate change - Population growth - Removal of fuel wood - Overgrazing - Over-cultivation - Soil erosion

Question 41

How does population growth cause desertification?

Answer 41

Increased demand for food and fuel, which leads to deforestation and overgrazing.

Question 42

How does removal of fuel wood cause desertification?

Answer 42

It exposes the soil to erosion.

Question 43

How does overgrazing cause desertification?

Answer 43

By removing vegetation and exposes the soil to erosion.

Question 44

How does over-cultivation cause desertification?

Answer 44

When crops are planted in the same place repeatedly, the soil loses nutrients and becomes less fertile. This makes it harder for crops to survive, and without plants to hold the soil together, it's more likely to be washed or blown away.

Question 45

How does soil erosion cause desertification?

Answer 45

It removes nutrients from the soil, making it difficult for plants to grow

Question 46

What three strategies are used to manage desertification?

Answer 46

- Water and soil management - Tree planting - Appropriate technology

Question 47

Explain how water and soil management reduce the risk of desertification and give an example.

Answer 47

Aims to prevent intense rainfall washing away loose soil and causing soil erosion. An example is low rock walls called bunds in parts of the Sahel that follow the contours of the land and any soil carried by water is deposited, creating a reasonable thickness of soil that can then be cultivated.

Question 48

Explain how tree planting reduce the risk of desertification and give an example.

Answer 48

Trees help prevent soil erosion by acting as an umbrella. Their roots also help bind the soil together. An example is in the Senegal region of the Sahel, the FAO of the UN initiated a project on planting Acacia trees which also creates economic help.

Question 49

Explain how use of appropriate technology reduce the risk of desertification and give an example.

Answer 49

Appropriate technology is cheap and sustainable. An example is in Senegal, where about 86% of the rural population depends on biomass for cooking which is bad for desertification, so they have fuel-efficient stoves that require 55% less firewood - reducing fuel costs and amount of vegetation used