Hot Deserts

Question 1

What are the challenges of developing hot desert environments?

Answer 1

Managing water supply

Extreme Temperatures

Inaccessibility

Challenge of developing infrastructure due to lack of resources

Question 2

How are extreme temperatures a challenge in developing hot deserts?

Answer 2

Workers and residents face severe consequences due to dehydration.

At night temperatures drop to below 0 and this high diurnal range makes it very difficult for people to adapt

Salinisation occurs due to high evaporation rates. Salt is drawn up through the soil making the top layers infertile.

Question 3

How is managing water supply an issue in hot desert environments?

Answer 3

In the western desert nearly all the water is taken from the Colorado river and is used for irrigation, drinking water and leisure therefore as so much water is taken from the Delta where the river meets the sea near Mexico it has dried up. This leads to conflicts.

Question 4

How is inaccessibility an issue in a hot desert?

Western Desert

Answer 4

The sheer scale and harsh conditions such as salt flats and mountain ranges make building roads very hard. Only experienced drivers can drive over sand and gravel so with the extreme heat inexperienced drivers can easily break down and become stranded in the heat.

In the western desert, the population density is less than one person per kilometer square

Question 5

How have people adapted to the western desert’s tough climate?

Answer 5

Thick walls to keep the heat out

Flat roofs to collect rainwater

White-washed buildings to reflect the heat

Question 6

What are the economic benefits and ecological costs of taking water from the Colorado River to the western desert?

Answer 6

BENEFITS - Brings water to major US cities in the western desert such as Las Vegas and Los Angeles. Also brings life-giving water to allow farmers to grow crops in places such as the Coachella Valley

COSTS - Starves the river lower down due to dams such as the GLEN CANYON DAM. This causes political arguments between Mexico and the US. Also as a result of limited water lower-down sandbanks are starved of sediment so manu habitats are lost.

Question 7

How much agricultural money is gained as a result of Colorado’s aqueducts?

Answer 7

US $1.5 billion per year

Question 8

What is desertification?

Answer 8

The process of semi-arid grassland becoming drier and degraded, therefore turning into desert.

Areas at risk are on the borders of existing deserts, eg. Sahel

Question 9

What are the causes of desertification?

Answer 9

Population growth leads to more pressure on food and water resources which then leads to over-grazing, over-cultivation, and deforestation leading to soil erosion

Question 10

How is Darfur being affected?

Answer 10

Darfur is a region in Africa located on the fringes of the Sahara desert. There has been much conflict in Darfur (250 000 dead) and with a severe drought every 5 years food production cannot keep up with its growing population

As a result, people migrate to semi-arid areas of the desert which leads to overpopulation and therefore desertification.

Question 11

How can we tackle desertification?

Answer 11

Afforestation, planting trees so the roots bind the soil, and the leaves provide leaf litter for a rich humus layer therefore reducing deforestation. The Great Green Wall of Africa is an example of this which spreads across the Sahel.

This project provides hope for the future and employment for the impoverished. Will also bring about political cooperation. However, climate change is challenging the survival of the trees in the long term.

Fuel-efficient stoves reduce deforestation
Magic stones reduce soil being washed down slopes during heavy rainfall

Question 12

Where are hot deserts found?

Answer 12

On the tropics

Question 13

What are the soils like in hot deserts?

Answer 13

Soil forming is limited due to limited water and vegetation - infertile

Sandy, rocky soils

Salty due to hight rates of evaporation

Wind action forms massive sand dunes however dunes are not soil as there is no organic matter.

Once irrigated the land can become highly fertile for agriculture eg. Coachella Valley, California

Question 13

Hot Desert climate?

Answer 13

100-200 mm of rain a year

Diurnal temperatures due to cloudless skies - 35+ degrees in the day to sub 0 at night.

Question 14

How are plants adapted to Hot Deserts?

Answer 14

Cacti - Store water in their tissue. Spines also have small surface area to minimise transpiration. Widespread and deep root systems to access limited water supply.

Acacia trees - Drought resistant. They have short fat trunks that act as reservoirs for excess water. Fire Resistant. 50m deep roots.

Brittlebush only germinate after rainfall.

Question 15

How are animals adapted to Hot Deserts?

Answer 15

Camels - Humps that store fat that can be converted into water and energy when needed. Long eyelashes and closed nostrils to keep out sand. Wide feet that prevent them from sinking into the sand.

Desert foxes - Thick fur on the soles of their feet to protect them from the hot ground. Light-coloured fur reflects light

Nocturnal animals sleep when the sun is hottest, this saves their energy

Question 16

Why are deserts found on the tropics?

Answer 16

Air that rises over the equator heads polewards losing its moisture as rain. At this low altitude, the sun’s rays are still highly concentrated. Combined with the dry air this brings about arid conditions.

Question 17

What are some ways we can tackle desertification?

Answer 17

Green Wall, stabilises the soil and will add valuable nutrients from leaf litter - 15km wide across the whole Sahel region. The Atlantic Ocean to the Indian Ocean. Will provide jobs for the poor and provide political stability.

Fuel-Efficient Stoves - Require less wood so less deforestation occurs on desert fringes

Sahel’s Magic Stones - Slows the flow of water off the compact ground giving it a chance to saturate the ground to form rich sediment for plant growth

Question 18

How are hot deserts interdependent?

Answer 18

Plants take up nutrients and water from the soil and then pass them on to animals that eat them.

In return, animals spread their seeds when they egest the plant.

Question 19

How does overgrazing in hot deserts have a knock-on effect?

Answer 19

This causes soil erosion as there are fewer plant roots holding the soil together.
The wind can blow fine particles of sand into the atmosphere causing dust clouds that limit rainfall.

This makes the desert more arid and plants, animals, and humans may die.

Question 20

How is biodiversity threatened in the desert?

Answer 20

Deserts have relatively low levels of biodiversity due to a lack of vegetation and rainfall.

However, biodiversity is higher along temporary ponds and rivers and desert margins however, this is also where human populations are highest.

Their activities increased desertification leading to a loss of biodiversity.