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Deserts - Coggle Diagram
Deserts
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Climate
The climate is very hot. Summer day time temperatures can exceed 40°C. However, at night the temperature can drop below 0°C.
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Hot deserts have two distinct seasons: summer, when the temperature ranges between 35-40°C, and winter, when the temperature ranges between 20-30°C.
Soil
Desert soils are thin, sandy, rocky and generally grey in colour.
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The surface of the soil may appear crusty. This is due to the lack of rainfall. As it is so hot water is drawn up to the surface of the soil by evaporation. As the water evaporates, salts are left behind on the surface of the soil.
Animal Adaptations
Camels -
- Have humps to store fat which a camel can break down into water and energy when nourishment is not available
- Rarely sweat, even in hot temperatures, so when they do take in fluids, they can conserve them for long periods
- Have large, tough lips that enable them to pick at dry and thorny desert vegetation
- Have broad, flat, leathery feet to spread their weight and provide protection from hot sand;
Fennec Foxes -
- Have thick fur on their feet protecting them from the hot ground
- Have large, bat-like ears radiate body heat and help keep them cool
- Have long, thick hair that insulates them during cold nights and protects them from the hot sun during the day
- Have light-coloured fur to reflect sunlight and keep their bodies cool
CASE STUDY - THAR DESERT
Development Opportunities -
- Mining - the desert has valuable reserves of minerals such as feldspar, phosphorite, gypsum and kaolin. These minerals are used to produce a range of things from cement to fertilisers and are therefore valuable. Limestone and marble are also quarried in the area. Limestone is used for building and producing cement, and marble is used in construction.
- Farming - irrigation in the Thar Desert has made commercial arable farming viable. Producing crops such as wheat and cotton has created many jobs and generated income for the local economy.
- Tourism - the Thar Desert National Park attracts many visitors who want to see some of the 120 species found there. Tourists explore the desert with local guides on camels. Tourism is an important source of income and creates many jobs for local people. The multiplier effect of tourism creates many development opportunities.
Challenges of Development -
- Extreme temperatures - temperatures in the Thar Desert can exceed 50°C in the summer months. It is hard for people to farm, work in mines or as tourist guides during these months as it is simply too hot. This makes development difficult.
- Water supply - the supply of water to the Thar Desert is precious and limited. With only 120-240 mm of rain falling per year in the desert, water must be used sensibly and sustainably. Without water the development of mining, farming and tourism and therefore the economy would not be possible. Some parts of the desert have experienced over-irrigation, which has caused waterlogging of the ground. Here the excess water has evaporated, leaving a layer of salt on the surface making it difficult to grow crops.
- Inaccessibility - the desert covers a huge area of 200,000 sq km. Most of the desert is inaccessible due to the extreme environmental conditions and poor infrastructure. Beyond the city of Jaisalmer, development is limited. This has created a honeypot site for tourists in Jaisalmer but not beyond. Inaccessibility to many parts of the desert has led to greater differences between rich and poor.
Desertification
Causes -
- Population growth - the population in some desert areas is increasing. In places where there are developments in mining and tourism, people are attracted by jobs. An increased population is putting greater pressure on the environment for resources such as wood and water.
- Removal of wood - in developing countries, people use wood for cooking. As the population in desert areas increases, there is a greater need for fuel wood. When the land is cleared of trees, the roots of the trees no longer hold the soil together so it is more vulnerable to soil erosion.
- Overgrazing - an increasing population results in larger desert areas being farmed. Sheep, cattle and goats are overgrazing the vegetation. This leaves the soil exposed to erosion.
Soil erosion - this is made worse by overgrazing and the removal of wood. Population growth is the primary cause of soil erosion.
- Climate change - the global climate is getting warmer. In desert regions conditions are not only getting warmer but drier too. On average there is less rain now in desert regions than there was 50 years ago.
Strategies to Reduce it -
- Planting more trees - the roots of trees hold the soil together and help to reduce soil erosion from wind and rain.
- Improving the quality of the soil - this can be managed by encouraging people to reduce the number of grazing animals they have and grow crops instead. The animal manure can be used to fertilise the crops grown. Growing crops in this way can improve the quality of the soil as it is held together by the roots of plants and protected from erosion. This type of farming is more sustainable.
- Water management - water can be stored in earth dams in the wet season and used to irrigate crops during the dry season. This is an example of using appropriate technology to manage water supplies in the desert environment.
Plants + Animals
Hot deserts have distinct characteristics that allow certain species to thrive in such an extreme environment. Plants and animals have developed adaptations which allow them to survive in hot and dry conditions.