23 terms

Hot Deserts location on the globe


Terms in this set (...)

What is a desert?
A desert is an area that receives less than 250mm of rainfall per year.
Where are hot deserts found?
The hot deserts of the world are located between 15° and 30° north or south of the equator. This is a zone of subsiding or sinking air. Air that rises due to the intense heat at the equator divides to flow north and south.
What is the climate like in a desert?
The location of the hot desert can be largely explained by the global atmospheric circulation. At these latitudes, air that has risen at the Equator descends forming a persistent belt of high pressure. This is why the lack of cloud and rain and the very high daytime temperatures.
What are desert soils like?
Desert soils tend to be sandy or stony with little organic matter due to the general lack of leafy vegetation. They are dry but can soak up water rapidly after rainfall. Evaporation draws salts to the surface, often leaving a white powder on the ground. Desert soils are not very fertile.
How have plants adapted to the desert?
Plants have developed a lot of adaptations:

1. Some plants have horizontal root systems, just below the surface.
2. Seeds can stay dormant for years but can germinate quickly when it rains.
3. Some plants store water in their roots, stems, leaves or fruits (called succulents).
4. Small leaves, spines, glossy and waxy leaves all help to reduce water loss.
5. Some plants have long taproots (7-10 metres) to reach groundwater.
How have animals adapted to the desert?
Animals have developed a lot of adaptations to deal with the lack of water and vegetation.

Many rodents are nocturnal surviving the extremely high daytime temperatures by living in burrows underground and only venturing out during the cooler nights. Snakes and lizards retain water by having lizard waterproof skin and producing only tiny amounts of urine. Camels are adapted to cope with many days without water.
Where is the Thar Desert?
The Thar Desert is one of the major hot deserts of the world. It stretches across north-west India and into Pakistan. The desert covers an area of 200,000km (squared). It is the most densely populated desert in the world.
What are is the environmental conditions of the Thar Desert.
The soils in the Thar Desert are sandy and not very fertile, with little organic matter to enrich them. They drain very quickly so there is little surface water. The landscape is mainly sandy hills with extensive mobile sand dunes and clumps of thorn forest vegetation - a mixture of small trees, shrubs and grasses. Rainfall in the Thar Desert is low between 100mm and 240mm per year and can reach temperatures up to 53 degrees.
What are the opportunities for development (Mineral extraction)?
The desert region has valuable reserves of minerals which are used all over India and exported across the world. The most important minerals are:
1. Gypsum (Used in making plasters for the construction industry and in making cement).
2. Feldspar (Used to make ceramics).
3. Phosphorite (Used for making fertiliser).
4. Kaolin (Used as a whitener in the paper).

There are also valuable reserves of stone in the region. At Jaisalmer, the Sanu limestone is the main source of limestone for India's steel industry.
What are the opportunities for development (Tourism)?
In recent years the Thar Desert, with its beautiful landscapes, has become a popular tourists destination. Tens of thousands visit the desert each year from neighbouring Pakistan. Desert safaris on camels, based at Jaisalmer, have become particularly popular with foreigners as well as wealthy Indians from elsewhere in the country.
What are the opportunities for development (Energy)?
The Thar Desert is a rich energy source.

1. Coal - there are extensive lignite coal deposits in parts of the Thar Desert and a thermal energy plant has been constructed at Giral.
2. Oil - A large oilfield has been discovered in the Barmer district which could transform the local economy.
3. Wind - Recently there has been a focus on developing wind power, a renewable form of energy. The Jaisalmer Wind Park was constructed 2001. This is India's largest wind farm.
4. Solar - with its sunny, cloudless skies, the Thar Desert offers ideal conditions for solar power generation.
What are the opportunities for development (Farming)?
Most of the people living in the desert are involved in subsistence farming. They survive in the hot and dry conditions by grazing animals on the grassy areas and cultivating vegetables and fruit trees. Commercial farming, which has grown in recent decades, has been made possible by irrigation. The construction of the Indira Gandhi Canal in 1958. Other crops grown under irrigation include pulses, sesame, maize and mustard.
What are the challenges to the Thar Desert (Extreme temperatures)?
The Thar Desert suffers from extremely high temperatures. Sometimes exceeds 50 degrees. This prevents challenges for people, animals and plants living in this environment.
1. Working outside in the heat of the day can be very hard, especially for farmers.
2. High rates of evaporation leads to water shortages which affect people as well as plants and animals.
3. Plants and animals have to adapt to survive in the extreme heat. Some animals are nocturnal, hibernating in the cooler ground during the daytime.
Why are there water shortages in the Thar Desert?
Water supply has become a serious issue in the Thar Desert. As the population has grown and farming and industry have developed, demand for water has increased. Water in this region is a scarce resource. The desert has low annual rainfall, high temperatures and strong winds. This causes high rates of evaporation.
What are the sources of water in the Thar Desert?
There are several sources of water in the Thar Desert.

1. Traditionally, drinking water for people and animals is stored in ponds, some of which are natural (tobas) and other are man-made (johads).
2. There are a few rivers and streams that flow through the desert, such as the River Luni which feeds a marshy area called the Rann. But these are intermittent, and flow only after rainfall. Most settlements are found alongside these rivers.
3. Some water can be obtained from underground sources (aquifers) using wells but this water is salty and not very good quality.
What is the function of the Indira Gandhi Canal (Thar Desert)?
The main use of the canal is to irrigate the desert. This source of freshwater has transformed an extensive area of the desert and has revolutionised farming in the region. Commercial farming takes place growing crops such as wheat and cotton now flourishes in an area that used to be a desert.
Two of the main areas to benefit from the canal are centred on the cities of Jodhpur and Jaisalmer were over 3500km (squared) of land is under irrigation. The Canal provides drinking water to people.
What are the challenges to the Thar Desert (Accessibility)?
Due to the very extreme weather and the presence of vast barren areas, there is a very limited road network across the Thar Desert. The high temperatures can cause the tarmac to melt and strong winds often blow sand over the roads. Many places are accessible only by camel, which is the traditional transport in the region. Public transport involves seriously over-worked bus services.
What is desertification?
Desertification happens where land is gradually turning into desert, usually on the edges of an existing desert. This can occur when land is overgrazed by livestock or stripped of vegetation by people collecting firewood. Once exposed to be weather, it will crack and break up. It will then be eroded by wind and water.
Where is desertification a problem?
Most of the areas at risk from desertification are on the borders of existing deserts, for example, the Sahara Desert in Africa.
What causes desertification?
Desertification can be caused by natural events, such as droughts, as well as poor land management. The areas close to deserts are ecologically very fragile. Slight changes in temperature and rainfall associated with climate change can have serious impacts. This makes these semi-deserts even more prone to overgrazing or over-cultivation.
How can desertification be reduced by making deserts National parks?
In some parts of the world, hot deserts areas at risk of desertification have been protected by making them national parks. The Desert National Park in the Thar Desert was created in 1992 to protect some 3000km square of the desert to reduce desertification.
How can desertification be reduced by making water and soil erosion?
Commercial farming in hot deserts often involves irrigation. Water from underground sources or
What causes desertification?
The causes of desertification are as followed:

1. Soil erosion is often linked to desertification. When vegetation has been destroyed the soil is exposed to the wind and the rain making it vulnerable to erosion.
2. Over-cultivation resulting from the need to produce more food can lead to the soil becoming exhausted. It will turn to dust and become infertile.
3. Population growth is also increasing the demand for fuelwood. Trees are stripped of their branches and eventually die.
4. Population pressure can result in the land close to existing deserts being overgrazed. This means that there are too many animals to be supported by the limited vegetation. When vegetation has been destroyed and the land will turn to desert.
5. In some deserts regions, such as the Sahel on the southern fringes of the Sahara Desert, climate chnage is resulting in drier conditions and urnreliable rainfall. On average it now rains less than it did 50 years ago.