“ PHYSIOGRAPHIC DIVISION OF INDIA “Regional Classification of Himalayas and The Indo-Gangetic Plains” ” B.A – II - GEOG (HONS & SUBSIDIARY), PAPER –III, SECTION – A AMIT KUMAR ASSISTANT PROFESSOR DEPARTMENT OF GEOGRAPHY S.N SINHA COLLEGE, WARISALIGANJ, NAWADA LONGITUDINAL DIVISION OF HIMALAYA Longitudinally, the Himalayas can be divided into following sections : Name Position Extension in Km PUNJAB HIMALAYA Between Sindhu & Satluj 560 km KUMAON HIMALAYA Between Satluj & Kali 320 km NEPAL HIMALAYA Between Kali & Tista 800 km ASSAM HIMALAYA Between Tista & Dihang 720 km 1. The Punjab Himalayas: The 560 km long stretch of the Himalayas between the Indus and the Sutluj rivers is known as the Punjab Himalayas. A large portion of this sector lies in Jammu and Kashmir and Himachal Pradesh as a result of which it is also called the Kashmir and Himachal Himalaya. Karakoram, Laddakh, Pir Panjal, Zaskar and Dhaula Dhar are the main ranges of this section. II. Kumaon Himalayas: This section extends from Sutluj to Kali river valleys and is said to have 360 lakes, such as Naini Tal and Bhim Tal. The Pilgrimage centers (Badrinath, Gangotri) located in this section is of particular importance to the Hindus. III. Nepal Himalayas: This section extends from Kali to Tista and has the distinction of having some of the highest peaks in the world including Mt Everest. IV. Assam Himalayas: This section extends from Tista to Dihang. Pauhunri and Kulhakangari are noted peaks. THE INDO-GANGETIC PLAINS 1. It is an aggradational plain formed by the alluvial deposits of the Indus, Ganga and the Brahmaputra and their tributaries. 2. The plain stretches from west (from the banks of the Ravi and Sutluj) to east (the Ganga delta) to a length of 2400 km. 3. It is about 90-100 km wide in Assam, 160 km near the Rajmahal Hills, 200 km in Bihar, and 280 Km near Allahabad and 500 km in Punjab - Rajasthan 4. The plain merges into the Thar Desert in the south-west. A low watershed of the Delhi ridge (278 m) along the right bank of the Yamuna River separates the Satluj plains (a part of the Indus plain) from the Ganga plains. 5. According to the recent studies, the average depth of the alluvium has been estimated at about 1300-1400 m which goes on decreasing towards south and finally merging with the irregular edge of the peninsular block. Divisions of the Great Plains The Great Plains may be divided into a number of smaller units on the basis of the characteristics of the alluvium, surface gradient, drainage channels and regional world traits. The great plains are classified into four belts: The Bhabar belt The Terai belt The Bangar belt The Khadar belt Bhabar Plains: It lies all along the foot of the is from Siwaliks with remarkable continuity from the Indus to the Tista. It is generally 8 to 16 km wide belt consisting of gravel and unassorted sediments deposited by the Himalayan rivers in the foreland zone due to sudden break of slope. The porosity is so high that all streams disappear in the Bhabar tract leaving out only dry channels. Terai Plains: South of the Bhabar lies a 15-30 km wide marshy tract called terai where streams reappear to the surface. The Terai is more marked in the eastern part than in the west due to higher amount of rainfall. It is a zone of excessive dampness, thick forests, rich wild life and malarial climate. Bangar or Bhangar Plains: The Bhangar represents the uplands (alluvial terrace) formed by the deposition of the older alluvium and lie above the flood-limit of the plains. The main constituent of Bhangar is clay which at places gives way to loam and sandy-loam. Khadar Plains: The younger alluvium of the flood plains of the numerous rivers is called the Khadar or Bet (in Punjab). Its alluvium is light coloured and poor calcareous matter consisting of deposits of sand, silt, mud and clay. Delta Plains: Deltaic plain is an extension of the Khadar plain. It covers about 1.86 lakh sq. km of area in the lower reaches of the Ganga river (West Bengal). It mainly consists of old mud, new mud and marsh. REGIONAL CLASSIFICATION OF GREAT PLAINS On the basis of regional characteristics, the Great Plains may be divided into following four major regions: 1. The Rajasthan Plains: This includes Marusthali and Rajasthan Bagar areas (Steppe lands) to the west of the Aravalli mountains. A part of the plain has also been formed by the recession of the sea as is evidenced by the occurrence of several brackish water lakes in the region, i.e. Sambhar, Degana, Kuchaman, Pachpadra, Didwana and Lunkaransar Tal from which table salt is obtained. At present Luni is the only flowing river which is lost in marshy land of Rann of Kutch. Most of the Rajasthan Plains are covered by vast stretches of sand. Western part is covered by shifting sand dunes locally known as Dhiran. The eastern part of the Thar is drained by a number of short seasonal streams originating in the Aravalis and supports agriculture in some patches of fertile tracts called Rohi. The region is known for having largest island saline wetlands. The general slope of the Rajasthan Plain is from east to the west towards the Indus river. 2. The Punjab-Haryana Plains: The Punjab- Haryana Plains owe their origin to the aggradational activity of the Satluj, the Beas and the Ravi rivers. The region has two regional slopes, westward towards the Indus river and southwards the Rann of Kachchh. The south-eastern part of the plains bordering the Rajasthan Plains (near Hissar) is sandy and is characterized by shifting sand dunes. On micro regional basis the Punjab Haryana Plains may be divided into following categories 1. The Bari Doab (between the Beas and the Ravi) 2. The Bist Doab (between the Beas and the Satluj), 3. The Malwa Plain (occupying the central part of the region) 4. The Haryana-Bhiwani Bagar in the southern and south-eastern part of the region. 3 The Ganga Plains: The Ganga Plains extend from the Yamuna river in the west to the western borders of Bangladesh covering a distance of about 1,400 km and an average width of 300 km. The maximum height is found near Saharanpur (276m) from where it goes on decreasing towards the Sagar Islands (3 m). (a) The Upper Ganga Plain: It occupies a total area of 1, 49,029 sq. km. Besides the Ganga and the Yamuna, other important rivers of the region include Ramganga, Gomati, Ghaghara and Rapti etc. Upper Ganga Plains is divided into three micro units: 1. The Ganga-Yamuna Doab 2. The Rohilkhand Plain and 3. The Avadh Plain. (b) The Middle Ganga Plain: It occupies total area of 1, 400, 00 sq. km. The Middle Ganga Plain includes eastern Uttar Pradesh and the Bihar plains. There are two large troughs, which may be called Gorakhpur trough and Raxaul- Motihari trough of over 8,000 m deep. Besides Ganga, Gomati, Ghaghara, Rapti, Gandak, Kosi (in the north), and Son (in the south) are other important rivers of be the region. The Kosi, called 'Sorrow of Bihar' has shifted its course over 120 km in recent times. The Middle Ganga Plain can be broadly divided into two sub regions: 1. The Northern Ganga Plain. 2. The Southern Ganga Plain. The former is further divided into four micro units: 1. The Ganga Ghaghara Doab 2. The Saryupar Plain 3. The Mithila Plain and 4. The Kosi Plain. Similarly the Ganga Plain South is sub-divided into 1. The Ganga-Son Divide. 2. The Magadh Plain. 3. The Anga Plain. c) The Lower Ganga Plain: The Lower Ganga Plain incorporating an area of 80,968 sq. km, extends from the foot of the Darjeeling Himalaya in the north to the Bay of Bengal in the south. The eastern part of the Plain is drained by Sankosh) joining the Brahmaputra, and the western part by the tributaries (Mahananda, Purnabhaba, Ajay, Damodar, Dwarkeswar, Rupnaryan) of Ganga (Padma- Bhagirathi). The Brahmaputra Plains: The Brahmaputra Plains, also called as Assam Valley, are the easternmost part of the Great Plains drained by the Brahmaputra and its tributaries. These plains from Sadiya (in the east) to Dhubri (near Bangladesh border in the west) are about 720 km long and about 80 km wide covering a total area of about 56,274 sq. km. The general altitude of the valley ranges from 130 m in the east to 30m in the west (Sadiya 130m, Dibrugarh 105m, Sibsagar 97m, Jorhat 87m, Tezpur 79m, Guwahati 55m, and Dhubri 34m) with an average slope of 12 cm per km. Majuli (area 929 km²) is the largest river island in the world. The Assam Valley is divided into two sub regions: 1. Upper Assam Valley 2. Lower Assam Valley. The Upper Assam Valley include the districts of Lakhimpur and Sibsagar and Tezpur Tahsil of Darrang district. The Lower Assam Valley consists of Dhubri, Goalpara, Barpeta, Kamrup, Nagaon and Darrang districts..