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 Rajasthan

PHYSIOGRAPHY

Western Sandy Plains

About 61% of the state area consists of sandy plains which lies to the west and north of Aravalli hills. The region is charaterised by arid landscape-barren hills, level rocky structural plains, rock cut pediments, gravel pavements, shallow colluvial plains, other sandy plains with alluvium underneath, sandy hummocks and low sand steaks, sand dunes of various kinds and interdunal plains. These plains have large sand dunes of height 50 to 100 meters and 8 to 10 km in length. In Barmer & Jaisalmer sand dunes are large but stable while in Churu, Sikar & Nagaur districts shifting sand dune are found. This region is most inhospitable region of the state; with scarcity of water the living conditions are very harsh.

The Luni Jawai plains occurs in the district of Jodhpur, Pali, Jalore, Sirohi, and in the southern part of the Nagaur. It contain the only integrated drainage system in the Thar desert. The Luni originates in the Aravalli hill ranges nears Ajmer and flows south-westward to the great Rann of Kutch. Enroute it is joined by numerous tributaries from the Aravallies, like the Lilri, the Guhiya, the Bandi, the Mirthri, the Sukri, the Jawai, etc. All these streams are ephemeral and have wide sandy beds. Tributaries from the isolated hills and rocky uplands in the plains also contributes to the flow in the Luni.The major tributaries originating in this zone, and joining the Luni, are two Jojris near Jodhpur and Pipar, the Luniwala near Siwana and the Sagi further southnear Bhinmal. All these streams register some flow during good monsoon rains and flash floods during spells of very high rainfall. All these streams form the vast alluvial plains through which they flow. Younger alluvial plains along the major streams give assured cultivation because of ground water, the older alluvial plains, the occasional isolated hills with fringing pediments and buried pediments, sand dunes with interdunal plains are the dominant landforms. The ranns of Pachpadra, Sanwarla and Kaparda are important saline depressions. These salt affected alluvial plains are more numerous near the confluence of the Luni with the Great Rann.

The Shekhawati tract is in Jhunjhunu, Sikar and Churu districts and northern part of Nagaur district. This zone has very few streams, most of which disappears after flowing for short distances in the sandy plains. The important streams are Mendha and Rupangarh which originate in the Aravalli hill range sand drain into the Sambhar salt lake. The other major stream Kantli flows north-westwards from Aravallies and disappear in the sandy plains near Rajgarh. The rainfall in this zone is higher than in the west and hence sand dunes in this zone support more vegetation.

Much of the Ganganagar district is occupied by vast alluvial Ghaggar flood plains. The wide dry valley of Ghaggar is now known to be that of the legendary Saraswati river which originated in the Himalayas. The dry valley passes through Hanumangarh, Suratgarh and Anupgarh, before entering into the Pakistan. Dry valleys of the Drishadvati, a major tributary of the Saraswati , occur in the Nohar-bhadra area in the eastern part of Ganganagar district. Canals have been constructed through almost all the dry valleys , making the lands around them very productive . The important canal systems are the Gang canal system , the Bhakra canal system, the west Yamuna canal system and the Indira Gandhi canal system. However, problems of water logging and salinity have also come up at places. The most notable examples are between Suratgarh and Anupgarh . Low sand dunes and sandy hummocks are scatteredly distributed on the deep sandy alluvial plains in this zone. Barchans have appeared in some parts of the plains because of deep ploughing of the soil without assured supply of canal water.

 The Aravalli hill ranges, the oldest mountains of India constitute the most dominant hilly area of Rajasthan . The ranges run diagonally across the state from north-east Delhi to south-west upto the plains of Gujarat, covering a distance of about 692 kms. Within Rajasthan, the ranges run from Khetri in the north-east to Khed Brahma in the south-west for a length of about 550 kms. In the north-east , the hill ranges become more prominent near Khetri and Alwar. Towards the south-west , the ranges become more prominent with peaks upto 1055 m above MSL. It is also a major water divide. The area to its east is well drained by several integrated drainage systems, while the area to the west has only one integrated drainage system, that is the Luni drainage system in the south-eastern part of the desert. The average height of this region is 600 meters above MSL, and highest at Guru Shikar in Mount Abu (1727 Meters). Mewar hills and Marwar hills are the some of the offshoots of Aravallies.

The eastern plains have rich alluvial soils drained by seasonal rivers, cover most part of Alwar, Bharatput, Sawai Madhopur, Bundi and Kota districts. The region of Banas plain is a broad plain having an altitude of 150 to 300 m MSL, with slope towards east. This plain is drained by Banas river through the northern part of Chitaurgarh and Udaipur district and several of its tributaries. The areas of Bhilwara, Tonk, Ajmer, Jaipur, Dausa and Sawai Madgopur are within catchment of Banas river. The tributaries like Kothari, Dain, Sohadra, Manshi, Bandi, Dhundh, Morel and Kareli join the Banas on its left bank side, while Berach, Wagan and Gambhiri, join it on the right bank side. The Banas is the major tributary of the river Chambal which ultimately joins the river Yamuna. The alluvium deposits become thin towards west where the plain is higher and more irregular, while in the east the thichness of alluvium increases. Another zone in this is of the Chappan plains which lies in the south-eastern part of Udaipur, Banswara, Dungarpur and southern part of Chittorgarh districts. The area is drained by tributaries of Mahi river which ultimately reaches the Arabian sea through the Gulf of Cambay.

Southern and south-eastern Rajasthan is mostly a plateau. The Hadauti plateau, having intrusions of black volcanic rocks into the Vindhyans, extends to a great part in Jhalawar, Baran and Kota districts. The Malwa plateau also extends into the southern part of Chittorgarh and Banswara districts having an average altitude of 500 m above MSL and is dotted with isolated low ranges at few places. This plateau in Rajasthan occurs in the upper catchment of the Chambal river to the south-east of the Mewar plains. The greater part of this area is drained by the river Chambal and its right bank tributaries like Kali Sindh, Parwan and Parvati. This plateau has two defined units of Vindhyan scrapland Deccan lava plateau.



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