मराठी
CISCEISC (Arts) Class 12
प्रश्नपत्रिका३७२
पाठ्यपुस्तक उत्तरे१६६८१
महत्वाचे प्रश्न आणि उत्तरे५८८५
संकल्पना स्पष्टीकरण आणि व्हिडिओ९५३
टाइम टेबल१५
अभ्यासक्रम

Overview of Drainage

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CISCE: Class 12

Key Points: Evolution of the Indian River System

  • Importance of Rivers: Rivers are the lifelines of India, and the drainage pattern is mainly influenced by the relief of land.
  • Two Major River Systems: On the basis of evolution, Indian rivers are divided into Himalayan rivers and Peninsular rivers.
  • Himalayan Rivers: The Indus, Ganga and Brahmaputra originate in the Tibetan Highlands, flow parallel to the Himalayas, and then cut deep gorges.
  • Antecedent Drainage: Himalayan rivers existed before the formation of the Himalayas and cut through rising mountains, forming deep gorges—hence they show antecedent drainage.
  • Indobrahma Theory: A mighty ancient river called Indobrahma once carried the combined flow of the Indus, Ganga and Brahmaputra and later broke into present river systems.
  • Break-up of Indobrahma: Its dismemberment occurred due to uplift in the western Himalayas and headward erosion by tributaries; Yamuna later became a tributary of the Ganga.
  • Peninsular Rivers: These rivers are older and mature, flow mostly west to east, show lateral erosion, and Narmada and Tapi flow west in rift valleys formed by faulting.
CISCE: Class 12

Key Points: The Drainage Systems of India > The Himalayan River Systems

  • Three Main Himalayan River Systems:
    Himalayan rivers are divided into Indus, Ganga, and Brahmaputra drainage systems.
  • Indus Drainage System:
    The Indus originates near Manasarowar Lake in Tibet (5180 m) and flows to the Arabian Sea. Its main tributaries are Jhelum, Chenab, Ravi, Beas and Satluj.
  • Important Indus Tributaries:
    i. Jhelum rises from Verinag and joins Chenab in Pakistan.
    ii. Chenab (Chandrabhaga) flows through deep gorges near Kishtwar.
    iii. Ravi and Beas originate near Rohtang Pass.
    iv. Satluj originates from Rakas Lake and has Bhakhra Dam.
  • Ganga Drainage System:
    The Ganga originates in the Garhwal Himalayas (6600 m) and is formed at Devaprayag by the meeting of Alaknanda and Bhagirathi.
  • Ganga Tributaries:
    Important tributaries include Yamuna, Ghaghara, Gandak and Kosi, all originating in the Himalayas and known for floods and shifting courses.
  • Brahmaputra Drainage System:
    Brahmaputra originates from Chemayungdung Glacier and is called Tsang Po in Tibet. It enters India as Dihang in Arunachal Pradesh.
  • Floods and Delta Formation:
    Brahmaputra becomes very wide (up to 8 km) in rainy season, causes floods, and joins the Ganga in Bangladesh to form the world’s largest delta.
CISCE: Class 12

Key Points: The Drainage Systems of India > The Peninsular Rivers

  • General Flow Pattern: Most Peninsular rivers originate from the Western Ghats and flow west to east to join the Bay of Bengal.
  • Main East-flowing Rivers: The important rivers flowing into the Bay of Bengal are Mahanadi, Godavari, Krishna and Cauvery.
  • Mahanadi River: It rises near Sihawa (Chhattisgarh), is 857 km long, flows through Odisha, and joins the Bay of Bengal.
  • Godavari River: It is the largest Peninsular river, rises in Nashik (Maharashtra), is 1465 km long, and is called Dakshina Ganga / Vridha Ganga.
  • Krishna and Cauvery:
    a) Krishna rises near Mahabaleshwar, is 1400 km long.
    b) Cauvery rises in Brahmagiri hills, is 800 km long, and is a perennial river because it gets water from both monsoons.
  • West-flowing Rivers: Narmada (1300 km) and Tapi (724 km) are exceptions as they flow westwards in rift valleys into the Arabian Sea / Gulf of Khambhat.
  • Other Important Rivers: Sabarmati and Mahi drain the north-west plateau, while Chambal, Sind, Betwa, Ken and Son flow northwards and join the Ganga system, with Chambal famous for ravines and badland topography.
CISCE: Class 12

Key Points: Differences between the Himalayan and the Peninsular River Systems

Himalayan River System Peninsular River System
Rivers are very long (some of the longest in India) Rivers are comparatively shorter
Have large catchment areas and basins Have smaller catchment areas and basins
More number of rivers Fewer rivers
Perennial rivers (fed by rain + snowmelt) Mostly seasonal rivers (rain-fed)
Flow through deep gorges Flow through shallow valleys
Form meanders and often change course Follow a straight course and rarely change
Form big deltas (Ganga-Brahmaputra is largest) and show antecedent drainage Form small deltas; Narmada-Tapi form estuaries and show consequent drainage
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