Class 9 Social Science Notes Chapter 3 (Drainage) – Contemporary India Book

Alright class, let's delve into Chapter 3, 'Drainage', from your Contemporary India I textbook. This chapter is crucial not just for your exams but also for understanding the physical geography of our country, which often forms a significant part of government exam syllabi. Pay close attention to the terms and locations.

Chapter 3: Drainage - Detailed Notes for Government Exam Preparation

1. Introduction: What is Drainage?

• Drainage: Refers to the river system of an area. It describes the pattern and network of rivers, streams, and lakes that drain water from a specific region.
• Drainage Basin: An area drained by a single river system (the main river and its tributaries) is called a drainage basin or catchment area. Think of it like a large funnel collecting water.
• Water Divide: An elevated area, such as a mountain or an upland, that separates two drainage basins is known as a water divide. For example, the Western Ghats act as a major water divide for Peninsular rivers. Ambala is located on the water divide between the Indus and the Ganga river systems.

2. Drainage Systems in India

Indian rivers are broadly divided into two major groups based on their origin:

• The Himalayan Rivers: Originate from the Himalayas.
• The Peninsular Rivers: Originate in the Peninsular Plateau.

Key Differences:

3. The Himalayan Rivers

These are ancient rivers that existed even before the Himalayas uplifted. They cut deep gorges through the mountains.

• Major Systems:

  • The Indus River System
  • The Ganga River System
  • The Brahmaputra River System

• Characteristics:

  • Perennial: Fed by both rain and melting snow/glaciers.
  • Long Courses: Travel vast distances from source to sea.
  • Intensive Erosion: Cut deep gorges (e.g., Indus Gorge), V-shaped valleys in upper reaches. Carry huge loads of silt and sand.
  • Depositional Features: Form meanders, ox-bow lakes, floodplains, braided channels, and large deltas in middle and lower courses.

a) The Indus River System

• Source: Near Lake Mansarovar in Tibet ( कैलाश Range).
• Entry into India: Enters India in the Ladakh region. Forms a picturesque gorge.
• Tributaries in India: Zaskar, Nubra, Shyok, Hunza (in Kashmir region).
• Flow: Flows through Baltistan and Gilgit, emerges from mountains at Attock.
• Major Tributaries (joining in Pakistan): The Satluj, Beas, Ravi, Chenab, and Jhelum join together to enter the Indus near Mithankot in Pakistan. This section is also known as the 'Panjnad'.
  • Jhelum: Rises from Verinag spring (Pir Panjal range).
  • Chenab: Formed by two streams, Chandra and Bhaga (Himachal Pradesh). Largest tributary of Indus.
  • Ravi: Rises west of Rohtang Pass (Kullu hills).
  • Beas: Rises from Beas Kund near Rohtang Pass. Flows entirely within India.
  • Satluj: Rises near Mansarovar (Rakas Lake) in Tibet (Langchen Khambab). Enters India through Shipki La pass. Bhakra Nangal project is on this river.
• Length: About 2900 km (one of the longest rivers in the world).
• Drainage: A little over one-third of the basin is in India (Ladakh, J&K, Himachal Pradesh, Punjab). The rest is in Pakistan and China.
• Indus Water Treaty (1960): India can use only 20% of the total water carried by the Indus river system. This water is used for irrigation in Punjab, Haryana, and southern/western parts of Rajasthan.

b) The Ganga River System

• Source: The headwaters, called 'Bhagirathi', are fed by the Gangotri Glacier.
• Formation: Bhagirathi is joined by the Alaknanda at Devprayag in Uttarakhand. From Devprayag onwards, it is known as the Ganga. (Alaknanda's source is Satopanth glacier above Badrinath. Its tributaries include Pindar, Mandakini, Dhauliganga).
• Course: Emerges from mountains onto the plains at Haridwar.
• Length: Over 2500 km.
• Drainage Basin: Largest in India. Covers states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, West Bengal.
• Tributaries (Left Bank - from North/Himalayas):
  • Yamuna: Largest tributary. Rises from Yamunotri Glacier. Flows parallel to Ganga and joins it at Prayagraj (Allahabad). Its own tributaries include Chambal, Betwa, Ken (Peninsular origin).
  • Ghaghara: Rises in Mapchachungo glacier (Tibet). Joins Ganga in Bihar. Tributary: Sarda (Kali/Mahakali).
  • Gandak: Rises in Nepal Himalayas. Joins Ganga at Sonpur near Patna.
  • Kosi: Rises in Nepal Himalayas ( सप्त कोशी ). Known as the 'Sorrow of Bihar' due to frequent devastating floods. Changes course frequently.
• Tributaries (Right Bank - from South/Peninsula):
  • Chambal: Rises in Malwa plateau (MP). Known for badland topography (Chambal ravines).
  • Betwa: Rises in Vindhya range (MP).
  • Son: Rises in Amarkantak plateau. Joins Ganga near Patna.
• Delta Formation: Flows eastwards till Farakka (West Bengal). Here, the river bifurcates:
  • Bhagirathi-Hooghly: A distributary, flows south through deltaic plains to the Bay of Bengal (Kolkata is on its banks).
  • Main Stream (Padma): Flows southwards into Bangladesh, joined by Brahmaputra (called Jamuna in Bangladesh). The mighty river formed by Ganga and Brahmaputra is known as Meghna before flowing into the Bay of Bengal.
• Sundarban Delta: Formed by Ganga and Brahmaputra. World's largest and fastest-growing delta. Name derived from Sundari trees. Home to Royal Bengal Tiger.
• Conservation: Namami Gange Programme (integrated conservation mission), Ganga Action Plan (earlier initiative).

c) The Brahmaputra River System

• Source: Tibet, east of Mansarovar lake, very close to sources of Indus and Satluj (Chemayungdung glacier).
• Course in Tibet: Flows eastward parallel to the Himalayas. Known as Tsangpo (meaning 'The Purifier'). Carries less water and silt in Tibet (cold, dry area).
• Entry into India: Takes a 'U' turn near Namcha Barwa peak (7757 m) and enters India in Arunachal Pradesh through a deep gorge. Here it is called Dihang.
• Formation of Brahmaputra: Joined by Dibang, Lohit, Kenula and many other tributaries in Assam to form the Brahmaputra.
• Course in Assam: Flows through a region of high rainfall. Carries large volume of water and considerable silt. Has a braided channel (many interlacing channels) for its entire length in Assam. Forms many riverine islands.
  • Majuli: World's largest riverine island, formed by Brahmaputra.
• Flooding: Prone to devastating floods during monsoon season in Assam and Bangladesh due to heavy rainfall and silt deposition raising the river bed.
• Course in Bangladesh: Enters Bangladesh and is known as Jamuna. Joins Padma (Ganga) and eventually forms the Meghna before emptying into the Bay of Bengal.

4. The Peninsular Rivers

These rivers originate in the Peninsular Plateau and Central Highlands.

• Characteristics:

  • Seasonal: Flow depends on rainfall. Dry up or have reduced flow during the dry season.
  • Shorter/Shallower Courses: Compared to Himalayan rivers.
  • Origin: Most originate in the Western Ghats and flow towards the Bay of Bengal (Eastward flow). Some originate in Central Highlands and flow westwards.
  • Drainage Basins: Relatively smaller.

• Main Water Divide: Western Ghats.

a) East Flowing Rivers (Form Deltas)

• Mahanadi:
  • Source: Highlands of Chhattisgarh.
  • Length: About 860 km.
  • Basin: Maharashtra, Chhattisgarh, Jharkhand, Odisha.
  • Delta: Forms a delta before flowing into Bay of Bengal. Hirakud Dam is on this river.
• Godavari:
  • Source: Slopes of the Western Ghats in Nasik district, Maharashtra.
  • Length: About 1500 km (Largest Peninsular river).
  • Basin: Largest among Peninsular rivers. Covers parts of Maharashtra, Madhya Pradesh, Odisha, Andhra Pradesh, Telangana.
  • Tributaries: Purna, Wardha, Pranhita (confluence of Wardha & Wainganga), Manjra, Wainganga, Penganga. (Note: Manjra joins from the south, others mostly from the north).
  • Nickname: Often referred to as 'Dakshin Ganga' (Ganga of the South) due to its large size and extent.
  • Delta: Forms a large delta.
• Krishna:
  • Source: Near Mahabaleshwar (Western Ghats).
  • Length: About 1400 km.
  • Tributaries: Tungabhadra, Koyana, Ghatprabha, Musi, Bhima.
  • Basin: Maharashtra, Karnataka, Andhra Pradesh, Telangana.
  • Delta: Forms a delta. Nagarjuna Sagar dam is on this river.
• Kaveri:
  • Source: Brahmagiri range of Western Ghats (Karnataka).
  • Length: About 760 km.
  • Basin: Karnataka, Kerala, Tamil Nadu.
  • Waterfalls: Forms the second biggest waterfall in India - Sivasamudram Falls (used for hydroelectric power).
  • Flow: Carries water somewhat consistently throughout the year because upper catchment receives rainfall during summer monsoon and lower catchment during winter monsoon (NE monsoon).
  • Delta: Forms a delta ('Garden of Southern India'). Known for disputes over water sharing (Kaveri Water Dispute).

b) West Flowing Rivers (Form Estuaries)

• Narmada:
  • Source: Amarkantak hills in Madhya Pradesh.
  • Flow: Flows westwards through a rift valley between Satpura (south) and Vindhya (north) ranges.
  • Features: Creates picturesque locations like 'Marble Rocks' near Jabalpur and 'Dhuandhar falls'.
  • Length: About 1312 km.
  • Basin: Madhya Pradesh, Gujarat.
  • Mouth: Forms an estuary before draining into the Arabian Sea.
  • Conservation: Sardar Sarovar Dam (associated with Narmada Bachao Andolan).
• Tapi (or Tapti):
  • Source: Satpura ranges, in Betul district of Madhya Pradesh.
  • Flow: Flows westwards through a rift valley, parallel to Narmada but south of it.
  • Length: About 724 km.
  • Basin: Madhya Pradesh, Gujarat, Maharashtra.
  • Mouth: Forms an estuary before draining into the Arabian Sea.
• Other West Flowing Rivers: Sabarmati, Mahi (both rise in Central Highlands/Aravallis and drain into Gulf of Khambat), Bharathapuzha (Ponnani - longest river in Kerala), Periyar (Kerala). Coastal rivers are generally short.

5. Lakes

• Importance:
  • Help regulate river flow (store water during heavy rain, release during dry season).
  • Prevent flooding.
  • Used for generating hydropower.
  • Moderate climate of surroundings.
  • Maintain aquatic ecosystems.
  • Enhance natural beauty, promote tourism, provide recreation.
• Types in India:
  • Freshwater Lakes:
    • Most are in the Himalayan region, often formed by glaciers (e.g., Bhimtal, Nainital, Loktak, Barapani).
    • Wular Lake (J&K): Largest freshwater lake in India. Result of tectonic activity.
    • Dal Lake (J&K): Famous for houseboats and Shikaras.
  • Saltwater Lakes:
    • Sambhar Lake (Rajasthan): Largest inland saltwater lake in India. Used for salt production.
  • Ox-bow Lakes: Formed by meandering rivers cutting off loops (common in Ganga plains).
  • Lagoons: Formed by spits and bars in coastal areas, trapping seawater. E.g., Chilika Lake (Odisha) - largest saltwater lagoon in India, Pulicat Lake (AP/TN), Kolleru Lake (AP).
  • Lakes in Inland Drainage Basins: Sometimes seasonal (e.g., Sambhar).
  • Man-made Lakes (Reservoirs): Created by damming rivers for hydro-power generation. E.g., Guru Gobind Sagar (Bhakra Nangal Project on Satluj).

6. Role of Rivers in the Economy

• Historical Significance: River banks attracted settlers from ancient times (river valley civilizations). Cities developed along rivers.
• Modern Significance:
  • Water Source: Essential for domestic, industrial, and agricultural use.
  • Irrigation: Backbone of agriculture in India.
  • Navigation: Used for transport (though less prominent now compared to roads/rail). National Waterways are being developed.
  • Hydro-power Generation: Dams on rivers generate electricity.
  • Fishing: Livelihood for many communities.

7. River Pollution

• Causes:
  • Discharge of untreated sewage and industrial effluents into rivers.
  • Agricultural runoff (pesticides, fertilizers).
  • Domestic waste, dumping of garbage.
  • Religious offerings, immersion of idols.
  • Reduced flow due to excessive water diversion for irrigation/industry, decreasing the river's self-cleansing capacity.
• Impact: Adversely affects aquatic life, contaminates water sources, poses health risks.
• Concern: Growing domestic, municipal, industrial, and agricultural demand affects water quality. Large rivers like Ganga are heavily polluted.
• Solutions: Need for effective sewage treatment plants, industrial waste management, public awareness, and conservation efforts (like Namami Gange).

Multiple Choice Questions (MCQs)

1. Which of the following landforms separates two drainage basins?
   a) River Valley
   b) Water Divide
   c) Delta
   d) Estuary

2. The river Narmada originates from:
   a) Satpura Range
   b) Brahmagiri Hills
   c) Amarkantak Hills
   d) Slopes of the Western Ghats

3. Which one of the following lakes is a saltwater lake?
   a) Wular
   b) Dal
   c) Sambhar
   d) Gobind Sagar

4. Which is the largest Peninsular river?
   a) Krishna
   b) Godavari
   c) Mahanadi
   d) Kaveri

5. The river Brahmaputra is known as _______ in Tibet.
   a) Dihang
   b) Tsangpo
   c) Jamuna
   d) Meghna

6. Which river forms the Dhuandhar falls near Jabalpur?
   a) Tapi
   b) Mahanadi
   c) Narmada
   d) Son

7. The world's largest delta, the Sundarbans, is formed by which two rivers?
   a) Indus and Jhelum
   b) Ganga and Yamuna
   c) Ganga and Brahmaputra
   d) Krishna and Godavari

8. Which of the following is NOT a tributary of the Ganga river flowing from the Peninsular uplands (Right Bank)?
   a) Chambal
   b) Betwa
   c) Son
   d) Kosi

9. Majuli, the largest riverine island in the world, is located in which river?
   a) Ganga
   b) Indus
   c) Godavari
   d) Brahmaputra

10. Which type of drainage pattern does the Ganga river system exhibit in the Northern Plains?
    a) Radial
    b) Trellis
    c) Dendritic
    d) Centripetal

Answer Key for MCQs:

1. b) Water Divide
2. c) Amarkantak Hills
3. c) Sambhar
4. b) Godavari
5. b) Tsangpo
6. c) Narmada
7. c) Ganga and Brahmaputra
8. d) Kosi (Kosi is a left-bank tributary originating from the Himalayas)
9. d) Brahmaputra
10. c) Dendritic (The tree-branch like pattern is characteristic of dendritic drainage)

Remember to supplement these notes by carefully studying the maps provided in your textbook. Visualizing the river courses, their tributaries, and the areas they drain is extremely important for exams. Keep revising these concepts regularly. Good luck with your preparation!