Hot Desserts

Question 1

Hot Desert Characteristics

Answer 1

• located15-30 degrees north and south of the equator
• below 250mm rainfall
• daytime temperatures can reach 50degrees but usually average around 25
• summer and winter seasons
• low humidity between 10% - 30%
• saline, unfertile, sandy, rocky, grey soil
• low biodiversity

Question 2

Factors influencing the hot desert climate
+influence of pressure systems

Answer 2

• High pressure all year which means the air is descending and warming so precipitation does not occur because the air is not rising
• Prevailing winds are often from over land masses which means they contain little moisture
• Some deserts are in a rain shadow so there is little rainfall
• Cold ocean currents on the west side of continents may reduce summer temperatures due to the cooling effect of the ocean
  Influence of Pressure systems
• Air rises at the equator and when it reaches the upper atmosphere it moves north and south
• The air cools and starts to sink
• This creates a zone of high pressure at about 30° north and south of the equator
• Due to the sinking air, warm air cannot rise, condense and form clouds, resulting in high aridity

Question 3

Plant Adaptations

Answer 3

• Low growing - this helps to avoid water loss due to strong winds
• Thick stems - used to store water
• **Shallow roots **- these spread out near the surface to catch whatever rain falls
• Long roots - some plants have long tap roots instead of shallow roots to reach water deep underground
• Small leaves or needles - the smaller surface area reduces water loss

Question 4

Animal Adaptations

Answer 4

• Camels have a range of adaptations including **two sets of eyelashes and nostrils **which close to keep sand out of their ears and noses. They also store fat in their humps so they can survive for long periods without food or water
• ** Fennec Fox** - have large ears which help them to lose heat
• Insects and reptiles have** waterproof skin** to reduce water loss
• **Nocturnal **- some animals hunt at night to avoid the daytime heat

Question 5

Biodiversity Issues

Answer 5

• Low levels of precipitation and high temperatures in many areas of hot deserts lead to low biodiversity
• Where water is available there are higher levels of biodiversity
• When rainfall does occur in desert areas a desert bloom may follow
• Mining
• Climate Change
• Fuelwood gathering

Question 6

Opportunities Hot Deserts provide

Answer 6

**Energy **
* Solar energy in areas such as the Mojave, Desert
* Wind
* Coal mining such as the Thar coalfield
Mineral extraction
* Reserves of a range of minerals include copper, uranium, and coal in the USA Western Desert
Tourism
* Desert safaris in the Kalahari Desert
* Horseback riding in the Namib Desert
* Staying in a traditional Ger (Mongolian Yurt) in the Gobi Desert
* Balloon flights such as those over the Namib Desert
Agriculture
* Irrigation enables large scale agriculture in areas such as the Arabian Desert and Gobi Desert
* Subsistence farming occurs in many desert environments

Question 7

Challenges of Hot Deserts

Answer 7

Extreme temperatures: which can reach 50°C
* This leads to high levels of evaporation and water shortages
* Make working difficult
Accessibility
* There is a lack of roads due to low population
* Pipelines, roads and railways need to be built to withstand the high temperatures
* Sand often covers the roads
* Most of the desert areas are inaccessible
Water supply
* Water is often scarce due to low precipitation
* River flow is often unreliable
* Demand for water has increased as the population increases and there are more activities in the desert

Question 8

+definition

Natural Causes of Desertification

Answer 8

Desertification is the process by which land turns into desert, becoming drier and degraded
* **Soil erosion **leads to the loss of nutrients. Plants are unable to establish and grow
* Reduced vegetation means that nutrients are not added to the soil through the decomposition of dead organic matter
* Rainfall patterns have become less predictable leading to drought and any vegetation dying due to lack of water

Question 9

Human Causes of Desertification

Answer 9

• Overgrazing means the vegetation has all gone due to the numbers of animals or the land does not have chance to recover
• Over-cultivation leads to all the nutrients being taken up by crops leaving none for future vegetation to grow
• Deforestation removes shade for the soil and means there are no roots which bind the soil together. This increases soil erosion, whilst decreasing infiltration and interception
• Population growth puts increased pressure on the land as people raise more animals and grow more crops

Question 10

Strategies to reduce Desertification

Answer 10

Water management
* Contour stones or bunds can be used to increase infiltration
* Earth dams can be used in the wet season to store water
Education
Education including:
* Sustainable farming methods including agroforestry and crop rotation, which help to keep the soil healthy
* Family planning to reduce population growth
Afforestation
* Tree planting, such as the Great Green Wall across the Sahel, helps to reverse desertification
* Nutrients in the soil are replaced by falling leaves and branches
* The trees increase animal and insect activity which helps improve soil quality
Contour stones or bunds
* These help to reduce soil erosion by:
* Reduce overland flow