Thar Desert
The Thar Desert (also known as the Great Indian Desert) is a desert
mainly located in the state of Rajasthan in northwest India. It continues
into Pakistan as the Cholistan Desert. It is a region of constantly shifting
sand dunes, with sparse vegetation in some areas.
Thar Desert is spread over northwestern India and eastern Pakistan covering
an area of about 4,46,000 square kilometres. The Thar desert is about
805 km (about 500 mi) long and about 485 km (about 300 mi) wide. It covers
four states of India and two states of Pakistan. The Thar Desert is bounded
on the northwest by the Sutlej River, on the east by the Aravalli Range,
on the south by the salt marsh known as the Rann of Kutch, and on the
west by the Indus Valley. NASA has prepared a satellite map of the Thar
Desert. http://www.gesource.ac.uk/worldguide/html/image_626.html
Indian desert
Indian Desert is the eastern part of the Thar Desert. It is spread over
four states in India, namely Punjab, Haryana, Rajasthan, and Gujarat covering
an area of 2,08,110 square kilometres. The maximum area is covered in
Rajasthan, about 3/5th of the total geographical area of the state. Of
the total desert in India 61% falls in Rajasthan, 20% in Gujarat and 9%
in Punjab and Haryana combined. The Indian Desert is said to be extending
at a rate of ½ km per year towards Punjab, Haryana, Uttar Pradesh
and Madhya Pradesh. Indian Desert is mainly inhabited by Hindus but Muslim
population is also there in minority. The Thar Desert also extends to
the southeast of Pakistan. Within south Pakistan it is inhabited by Sindhi
and kolhis.
Origin of Thar Desert
The origin of the Thar Desert is a controversial subject. Some consider
it to be 4000 to 10,000 years old, whereas others state that aridity started
in this region much earlier. Another theory states that area turned to
desert relatively recently: perhaps around 2000 - 1500 BCE. Around this
time the Ghaggar ceased to be a major river and now terminates in the
desert. It has been observed through remote sensing techniques that Late
Quaternary climatic changes and neotectonics have played a significant
role in modifying the drainage courses in this part and a large number
of palaeochannels exist.
Most of the studies have the same opinion with the palaeochannels of the
Sarasvati coinciding with the bed of present day Ghaggar and believe that
the Satluj along with the Yamuna once flowed into the present Ghaggar
riverbed. It is postulated that the Sutlej is the main tributary of the
Ghaggar and that subsequently the tectonic movements might have forced
the Satluj westwards, the Yamuna eastwards and the Ghaggar dried.
Remote sensing is widely useful for revealing the palaeochannels in the
desert areas using various digital image processing techniques of satellite
images. The present disorganized state of many streams in the Thar desert
of Western Rajasthan has been attributed by many investigators to change
in climate during Quaternary, and in the particular Holocene.
Climate of desert
The climate of the desert region is characterized by extremes of temperatures
ranging from even below freezing point in winters to as high as 52 °C
in summers. Rainfall is precarious and erratic, ranging from below 120
mm in the extreme west to 375 mm eastward. These rains are of the monsoon
type (July to September) and are generally of thundershowers. Mean wind
velocity varies from about 3 km per hour during December and January to
about 32 km per hour during May and June. Dust storms are also a normal
feature during summers. The velocity of dust storms may reach as high
as 130 km per hour, and may deposit as much as about 50 mm to 75 mm of
dust on the floor of residential buildings. Frosts are severe during winters
in the sandy areas and tree saplings up to 2 m height some times succumb
to such frosts.
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