ASIAN: DESERTS

Desert

Deserts in Asia are characterized by small amount of moisture. They receive an annual average rainfall of ten inches (25 cms) or less, and have an arid or hyperarid climate, characterized by a strong moisture deficit, where annual potential loss of moisture from evapotranspiration well exceeds the moisture received as rainfall.

The desert biome of the earth covers about 35 per cent of the total land area of the world. Deserts are very dry, receiving less than 25cm. The area of the desert biome in Asia are increasing as there is increasing desertification because of human over interaction. Deserts and xeric shrublands occur in all tropical, subtropical, and temperate climate regions. Desert soils tend to be sandy or rocky, and low in organic materials. Soil is generally saline or alkaline.

Adaptations:

Plants and animals in deserts of Asia are adapted to low moisture conditions. Hyperarid regions are mostly devoid of vegetation and animal life, and include rocky deserts and sand dunes. Vegetation in arid climate regions can include sparse grasslands, shrublands, and woodlands.

Deserts are inhabited by the Xerophytes which include succulent plants, geophytes, sclerophyll, and annual plants. Animals, including insects, reptiles, arachnids, birds and mammals, are frequently nocturnal to avoid moisture loss. In the southern Arizona, the unique Saguaro cactus grows too many meters in height and can survive up to 200 years of age if left undisturbed. First blooms do not appear until it is 50 to 75 years old.

Cold Deserts:

Cold desert in Asia is the Gobi desert occurs where seasonal shifting of the subtropical high is of some influence less than six months of the year. Specifically interior locations are dry because of their distance from moisture sources or their location in rain shadow areas on the leeward side of mountain ranges such as Himalayas and Andes.

Winter snows occur in the cold deserts but are generally light. Summers are hot, with highs varying between 30º and 40ºC. Night time lows -even in the summer, can cool 10º to 20ºC from the daytime high.

Map showing the location of deserts in Asia

Source: http://www.worldatlas.com/webimage/countrys/aslanddeserts.htm

Major Hot Deserts in Asia

The main hot deserts in Asia are as follows:-

  1. Arabian Desert
  • The Arabian Desert is the fourth largest desert in the world, with an area of about 2,330,000 square kilometers.
  • It is a vast desert wilderness stretching from Yemen to the Persian Gulf and Oman to Jordan and Iraq. It occupies most of the Arabian Peninsula, with an area of 2,330,000 square kilometers.
  • Animal species that are found are- Gazelles, oryx, sand cats, and spiny-tailed lizards are .They have adopted to desert conditions.
  • The rainfall amount is scanty and is generally around 100 mm, and the driest areas can receive between 30 and 40 mm of annual rain. Such dryness remains very rare throughout the desert, There are hardly any hyperarid areas in the Arabian Desert, in contrast with the Sahara Desert, where more than half of the area is hyperarid (annual rainfall below 50 mm).
  • Many species, such as the striped hyena, jackal and honey badger have become extinct in this area due to hunting, human encroachment and habitat destruction. Other species have been successfully re-introduced, such as the sand gazelle, and are protected at a number of reserves. Overgrazing by livestock, off-road driving, and human destruction of habitat are the main threats to this desert ecoregion.
  • The area is home to several diverse cultures, languages, and peoples, with Islam as the predominant faith. The major ethnic group in the region is the Arabs, whose primary language is Arabic. Nomadic Bedouin tribes have travelled through the Arabian Desert for thousands of years.
  • Ecological threats to the region include agricultural projects; human destruction of habitat; military activity (during Gulf War where US tanks eroded the top desert soil leading to increased sand dunes and dropping of depleted uranium on Iraqi targets that has become a cancer risk and source of water contamination); oil and gas production (Kuwait oil wells sabotage, dumping into Persian Gulf) and overgrazing by camels and goats, with increased herd size, and a more sedentary lifestyle amongst the Bedouin.

 

  1. Sahara Desert
  • The third largest desert in the world and the largest non-polar desert is the Sahara. Situated in North Africa, the Sahara makes up parts of Algeria, Chad, Egypt, Eritrea, Ethiopia, Libya, Mali, Mauritania, Morocco, Niger, Somalia, Sudan, Tunisia, and Western Sahara. The Sahara spans over 9,400,000 square kilometers across the continent, and is the world’s hottest desert.
  • It is covered by mountains, rocky areas, gravel plains, salt flats and huge areas of dunes. Contrary to popular belief, the desert is only 30% sand, and the rest 70% are gravel plains.
  • Areas in the central sometimes get no rain for years at a time.
  • Common vegetation – acacia, grasses and tamarisks.
  • Common animals – addax antelope, dorcas gazelle, fennec fox, horned viper, jackal, jerboa, sandgrouse and spiny-yailed lizard.
  • Nomads such as the Tuareg live here. It is crossed by Arab caravans since the 10th century.
  1. Gobi Desert
  • The fifth largest desert on Earth is Asia’s Gobi Desert. Situated in northwestern China and southern Mongolia, the Gobi Desert was created as a rain shadow from the tall Himalayan Mountains, which prevent rain from reaching Gobi.
  1. Thar Desert
  • It lies in India and Pakistan covering 200,000 sq. kms. It is mostly rocky sand and sand dunes with a majority part of the desert covered by sand dunes, and the rest covered by gravel plains.
  • Common vegetation- acacia, euphorbias, grasses, shrubs.
  • Animals- black buck, dromedary camel, great Indian bustard, Indian spiny-tailed lizard, jackel and sandgrouse.
  • Small villages of ten to twenty houses scattered throughout the Thar.

Kara Kum Desert
The Kara Kum covers 135,000 square miles, nearly 70 percent of Turkmenistan’s land. Because of the desert’s location along the Caspian Sea, the weather in Karakum is milder than many Asian deserts, which typically experience frigid winters and scorching summers.

Kyzyl Kum Desert
Crossing over Kazakhstan into Uzbekistan, this 115,000 square mile desert features a wide variety of flora and fauna. Though the area only receives 4 to 8 inches of rain per year, the rain occurs during the region’s cooler period so the water does not dissipate quickly and supports large migratory game.

Takla Makan Desert
China’s largest desert extends over 123,550 square miles. Composed primarily of shifting crescent sand dunes, the Takla Makan is one of the largest sandy deserts in the world. Despite the inhospitable and unpredictable nature of the desert sands, the Chinese government erected a road across the desert in the mid-1990s.

 

Why do hot deserts occur between 20-30 deg latitudes on the western margins on the Asian continent?

The occurrence of hot deserts in the 20-30 deg latitudes in both hemispheres and on the western margins of continents are due to a combination of multiple atmospheric and surface factors. The factor that determines the type of climate in any region is the amount of rainfall. Deserts are characterised by HOT and DRY conditions with very LESS RAINFALL. The following factors that occur in the 20-30 latitude regions contribute to the desertic conditions in these areas.

The occurrence of hot deserts in the 20-30 deg latitudes in both hemispheres and on the western margins of continents are due to a combination of multiple atmospheric and surface factors. The factor that determines the type of climate in any region is the amount of rainfall. Deserts are characterised by HOT and DRY conditions with very LESS RAINFALL. The following factors that occur in the 20-30 latitude regions contribute to the desertic conditions in these areas.

the north and south hemispheres respectively.Thus they flow over the entire continents from east to west. Because of this, by the time they reach the western margins of the continents all the moisture that they have been carrying would have been lost as rainfall for those regions along the way. What comes here – is just dry moisture free winds. Again this is not favouring the rainfall in this region resulting in dry desertic conditions.

Leeward sides of Mountains:

Another important factor that could be obeserved in some regions are the presence of High rise mountains along the western coasts.

Thus beacause of these reasons deserts in Asia are found between 20-30 deg latitudes on the western margins on the Asian continent.

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