hot deserts

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characteristics :

high temperatures in summer

greater evaporation than precipitation

strong winds and lack of cloud cover

considerable variation in the occurrence of precipitation

low humidity

adaptations : plants

small leaves - decreases water loss

waxy skin - reduce water loss

water storage - survive for longer without a water supply

adaptations : animals - camels

long eyelashes, hairy ears and closing nostrils to keep out sand

thick eyebrows which stand out and shade eyes from the sun

thick fur helps them to keep warm at night

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challenges :

extreme temperatures - due to the lack of cloud cover, daily temperatures can range from over 40 degrees during the day to below freezing at night. Exposure to high temperatures can cause illness or death, and healthcare may be a long distance away. The hot season is often too hot for tourists so employment in the tourism industry can be seasonal.

water supply - the Sahara has very low annual rainfall (less than 70mm in places) . Rainfall is unpredictable and most rivers only flow during part of the year. Providing enough water for workers, industry or irrigation is extremely hard. Deep boreholes are used to extract water stored naturally under the Sahara but this isn't sustainable because the supply isn't being replenished. Some desert resources are so valuable that new developments find ways of supplying the water they need, e.g. the phosphate mines in Morocco pipe water from a dam in central Morocco.

inaccessibility - the Sahara is huge ~ people and materials have to travel long distances ~ often by air, which is expensive. It's difficult to provide services e.g. medical care, to remote regions, making it hard for them to develop. Expensive pipelines have to be built to transport oil and gas from remote areas. It takes 5 days by truck to transport salt from salt mines in Mali out of the desert.

opportunities :

mineral resources - Morocco is now the world's largest exporter of phosphate (which is used in fertilisers, cleaning products, batteries etc.)

oil and gas - Algeria is a leader in oil exploration and extraction in the Sahara Desert. 60% of its income comes from the oil and gas industry. It has many oil fields, including Hassi Messaoud, and the industry employs over 40000 people.

solar energy - 12 or more hours of bright sunshine and cloudless skies everyday are ideal for generating solar power. A 100km squared area solar energy development in Tunisia is planned to supply enough electricity to meet the needs of 2 million homes in Western Europe by 2018.

tourism - many people are fascinated by remote and exotic desert locations. Sandboarding , carting and cross-desert treks are popular tourist activities in the Sahara, e.g. camel trekking in Morocco. Tourism in the Sahara itself remains on a small scale, though many people visit cities on the outskirts e.g. Marrakech.

farming - water is essential for plant growth o commercial agriculture in the Sahara is only possible where there is enough irrigation water ~ e.g. the Aswan Dam provides a year-round water supply in Egypt.

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desertification : what is it?

it is the degradation of land so that it becomes more desert-like ~ it becomes drier and less productive. A third of the world's land surface is at risk of desertification, particularly at the margins of deserts.

desertification : how can it be reduced?

water management - growing crops that don't need much water (e.g. millet, sorghum or olives) can reduce water use. Using drip irrigation on crops instead of surface irrigation means that the soil isn't eroded by lots of water being added all in one go.

tree planting - trees can be planted to act as windbreaks to protect soil from encroaching on farm land. Growing trees in amongst crops protects the crops (and soil) by providing shade, which reduces temperatures and evaporation rates.

soil management - leaving areas of land to rest in between grazing or planting lets them recover their nutrients. Rotating crops that use different nutrients from the soil means that the same nutrients don't keep being removed. Compost can be used to add extra nutrients to the soil.

appropriate technology - this involves using cheap, sustainable and easily available materials that are easy for local people to maintain. For example, sand fences (barriers to trap windblown sand) or terraces can be constructed to stabilise the soil and reduce erosion. The rate of deforestation can be reduced by using solar cookers, which use the sun's energy to heat food. They are cheap and easy to make, and don't require fuel wood to work.