Thar Desert
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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. [1] (http://www.gesource.ac.uk/worldguide/html/image_626.html)
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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.
Physiography and Geology
There are three principal landforms in the desert region i.e.
It is a desolate country where sand is piled up into huge wind blown dunes. The sand dunes are of three types viz., longitudinal parabolic, transverse and barchans. The first type, running NNE-SSW, i.e. parallel to the prevailing winds, occurs to the south and west of the Thar. The transverse dunes, aligned across the wind direction, to the east and north of Thar and barchans, with the conclave sides facing the wind in the interior, predominant in Central Thar. On the whole the Thar Desert slopes imperceptibly towards the Indus Plain and surface unevenness is mainly due to sand dunes. The dunes in the south are higher, rising sometimes to 152 m whereas in the north they are lower and rise to 16 m above the ground level. The Aravalli ranges form the main landmark to the south-east of Thar Desert. The more humid conditions that prevail near the Aravallis prevent the extension of Thar Desert towards the east and the Ganges Valley. In the heart of the sand covered area, the bare, dune free country of Barmer, Jaisalmer and Bikaner present an anomaly.
Desert soils
The soils of the Arid Zone are generally sandy to sandy-loam in texture. The consistency and depth vary according to the topographical features. The low-lying loams are heavier and may have a hard pan of clay, calcium carbonate or gypsum. The pH varies between 7 and 9.5. The soils improve in fertility from W & N.W. to E & N.E. Desert soils are Regosols of wind blown sand and sandy fluiratile deposits, derived from the disintegration of rock in the subjacent areas and blown in from the coastal region and the Indus valley. The desert soils occupy the districts of Jodhpur, Bikaner, Churu, Ganganagar, Barmer, Jaisalmer and Jalore. The Thar consists mainly of the wind-blown sand. The area is covered not only by sheet of sand but also of rockey projections of low elevations which constitute the older rocks of the country. Water is scarce and occurs at great depths, from 30 to 120 m from the ground level.
Some of these soils contain a high percentage of soluble salts in the lower horizons, turning water in the wells into poisonous. Being poor in organic matter they show a low loss on ignition. They contain varying amount of CaC03.
Biodiversity of desert
Stretches of sand in the desert are interspersed by hillocks and sandy and gravel plains. Due to the diversified habitat, the vegetation and animal life in this arid region is very rich. About 23 species of lizard and 25 species of snakes are found here and several of them are endemic to the region.
Some wildlife species, which are fast vanishing in other parts of India, are found in the desert in large numbers such as the great Indian bustard, the black buck, the Indian gazelle, and the wild ass in the Rann of Kutch. How these animals and insects survive in these harsh conditions, under such high temperature and without drinking water and green vegetation are amazing. They have evolved excellent survival strategies, their size is smaller than other similar animals living in different conditions, and they are mainly nocturnal. There are certain other factors responsible for the survival of these animals in the desert. Due to the lack of water in this region, transformation of the grasslands into cropland has been very slow. The protection provided to them by a local community, the Bishnois is also a factor.
The Desert National Park, Jodhpur, spread over an area of 3162 sq.km, is an excellent example of the ecosystem of the Thar Desert, and its diverse fauna. Great Indian bustard, black buck, chinkara, desert fox, Bengal fox, wolf, desert cat etc. can be easily seen here. Seashells and massive fossilized tree trunks in this park record the geological history of the desert. The region is a haven for migratory and resident birds of the desert. One can see many eagles, harriers, falcons, buzzards, kestrel and vultures. Short- toed eagles, tawny eagles, spotted eagles, lagger falcons and kestrels are the commonest of these.
Tal Chhapar Sanctuary is a very small sanctuary in district Churu, 210 km from Jaipur, in the Shekhawati region. This sanctuary is home to a large population of graceful black buck. Desert fox and desert cat can also be spotted along with typical avifauna such as partridge and sand grouse.
Natural vegetation of desert
The natural vegetation is classed as Northern Desert Thorn Forest (Champion 1936). These occur in small clumps scattered in a more or less open forms. Density and size of patches increase from West to East following the increase in rainfall. Natural vegetation of Thar Desert is composed of following tree, shrub and herb species.
Tree species
Acacia leucophloea, Acacia Senegal, Anogeissus rotundifolia, Prosopis cineraria, Salvadora oleodes, Tecomella undulata
Small trees and shrubs
Calligonum polygonoides, Acacia jacquemontii, Balanites roxburghii, Ziziphus nummularia, Calotropis procera, Suaeda fruticosa, Crotolaria burhia, Aerva tomentosa, Clerodendrum multiflrum, Leptadenia pyrotechnica, Lycium barbarum, Grewia populifolia, Commiphora mukul, Euphorbia nerifolia, Cordia rothii, Maytenus emorginata
Herbs
Eleusine compressa, Dactyloctenium scindicum, Cenchrus biflorus, Cenchrus setigerus, Lasiurus hirsutus, Cynodon dactylon, Panicum turgidum, Panicum antidotale, Dichanthium annulatum, Sporobolus marginatus, Saccharum spontaneum, Cenchrus ciliaris, Desmostachya bipinnata, Cyperus arenarius, Erogrostis species, Ergamopagan species, Phragmitis species, Typha species
The people of desert
The people of Thar Desret are simple and brave. The main occupation of the people in desert is Agriculture and animal husbandry. In past years there has been a tremendous increase in human population as well as animal population. This has led to improper control of grazing and extensive cultivation resulting into the deterioration of vegetation resources. The increase of human and livestock population in the desert has lead to deterioration in the ecosystem resulting in degradation of soil fertility also. The living standard of the people in the desert is low.
A large irrigation and power project has reclaimed areas of the northern and western desert for agriculture. The small population is mostly pastoral, and hide and wool industries are prominent.
There are around 50% Muslims and 50% Hindus in the Pakistani part of the Thar Desert. The desert turns into a green meadow after rain and is worth a visit. A colorful culture rich in tradition prevails in the desert. The people have a great passion for music and poetry.
See also
References
- Govt. of India. Ministry of Food & Agriculture booklet (1965)- soil conservation in the Rajasthan Desert- Work of the Desert Afforestation Research station, Jodhpur.
- Kaul, R.N. (1970). Afforestation in Arid zones (edited): Dr. W. JUNK N.V. Publishers The Hague.
- Gupta, R.K. & Prakash Ishwar (1975). Environmental analysis of the Thar Desert. English Book Depot., Dehra Dun.
- Kaul, R.N. (1967). Trees or grass lands in the Rajasthan- Old problems and New approaches. Indian Forester, 93: 434-435.
- Burdak, L.R. (1982). Recent Advances in Desert Afforestation- Dissertation submitted to Shri R.N. Kaul, Director, Forestry Research, F.R.I., Dehra dun.
- Yashpal, Sahai Baldev, Sood, R.K., and Agarwal, D.P. (1980). Remote sensing of the 'lost' Saraswati river. Proc. Ind. Acad. Sci. (Earth and Planet Sci.), V. 89, No. 3, pp. 317-331
- Bakliwal , P.C. and Sharma, S.B. (1980). On the migration of the river Yamuna. Journal Geological Society of India, Vol. 21, Sept. 1980, pp. 461-463.
- Bakliwal, P.C. and Grover, A.K. (1988). Signature and migration of Sarasvati river in Thar desert, Western India. Rec. Geol. Surv. Ind. V 116, Pts. 3-8, pp. 77-86.
- Rajawat, A.S., Sastry, C.V.S. and Narain, A. (1999-a). Application of pyramidal processing on high resolution IRS-1C data for tracing the migration of the Saraswati river in parts of the Thar desert. in "Vedic Sarasvati, Evolutionary History of a Lost River of Northwestern India", Memoir Geological Society of India, Bangalore, No. 42, pp. 259-272.
- Ramasamy, S.M. (1999). Neotectonic controls on the migration of Sarasvati river of the Great Indian desert. in "Vedic Sarasvati, Evolutionary History of a Lost River of Northwestern India", Memoir Geological Society of India, Bangalore, No. 42, pp. 153-162.
- Rajesh Kumar, M., Rajawat, A.S. and Singh, T.N. (2005). Applications of remote sensing for educidate the Palaeochannels in an extended Thar desert ,Western Rajasthan, 8th annual International conference, Map India 2005, New Delhi.de:Thar