1. Drainage Definition: It refers to the river system of an area. Smaller streams join to form a main river, which drains into larger water bodies like lakes, seas, or oceans.
    • Drainage Basin: Area drained by a single river system.
    • Water Divide: Elevated areas (mountains or uplands) separating two drainage basins.

Drainage Systems in India:

India’s drainage systems are influenced by its geography and divided into:

  1. Himalayan Rivers:
    • Characteristics:
      • Perennial: Have water all year due to rain and melting snow.
      • Originate from north of mountain ranges.
      • Form gorges and have long courses.
      • Perform erosion in upper courses and deposition in lower courses, creating features like meanders, oxbow lakes, and deltas.
    • Examples: Indus, Ganga, Brahmaputra.
  2. Peninsular Rivers:
    • Characteristics:
      • Seasonal: Depend on rainfall; flow reduces in dry seasons.
      • Shorter, shallower courses compared to Himalayan rivers.
      • Mostly flow eastward into the Bay of Bengal, forming deltas.
      • Some like Narmada and Tapi flow westward, forming estuaries.
    • Examples: Godavari, Krishna, Kaveri, Mahanadi.

Major River Systems:

1. Himalayan Rivers:

  • Indus River System:
    • Origin: Near Lake Mansarovar in Tibet.
    • Key Tributaries: Zaskar, Nubra, Shyok, Hunza, Jhelum, Chenab, Ravi, Beas, Satluj.
    • Flow: Through India (Ladakh, Punjab) and Pakistan into the Arabian Sea.
    • Length: 2,900 km (One of the world’s longest rivers).
    • Indus Water Treaty (1960): India uses only 20% of the water, primarily for irrigation.
  • Ganga River System:
    • Origin: Bhagirathi (Gangotri Glacier) merges with Alaknanda at Devaprayag.
    • Flow: From mountains to plains (Haridwar).
    • Tributaries: Yamuna, Ghaghara, Gandak, Kosi.
  • Brahmaputra River System:
    • Origin: Tibet (as Tsangpo).
    • Features: Carries less silt in Tibet but heavy silt in Assam; causes floods and forms riverine islands like Majuli.

2. Peninsular Rivers:

  • Narmada Basin:
    • Origin: Amarkantak Hills, Madhya Pradesh.
    • Flows westward through a rift valley; forms Marble Rocks and Dhuadhar Falls.
  • Tapi Basin:
    • Origin: Satpura ranges, Betul (Madhya Pradesh).
    • Shorter than Narmada; flows westward.
  • Godavari Basin:
    • Origin: Western Ghats, Maharashtra.
    • Largest Peninsular River; known as Dakshin Ganga.
  • Krishna Basin:
    • Origin: Mahabaleshwar.
    • Tributaries: Tungabhadra, Koyana, Ghatprabha, etc.
  • Kaveri Basin:
    • Origin: Brahmagiri range, Western Ghats.
    • Features: Forms Shivasamudram Falls, used for hydroelectric power.

Lakes in India:

  1. Types:
    • Freshwater Lakes: Mostly in the Himalayas (e.g., Wular, Dal, Bhimtal, Nainital).
    • Saltwater Lakes: Found in arid regions (e.g., Sambhar Lake).
    • Artificial Lakes: Created by dams (e.g., Guru Gobind Sagar).
  2. Importance:
    • Prevent floods.
    • Moderate river flow.
    • Support hydropower, tourism, and recreation.

Role of Rivers in Economy:

  1. Rivers provide water for:
    • Irrigation, drinking, and industries.
    • Navigation and hydroelectric power.
  2. Settlements and cities often develop along riverbanks due to the availability of water and fertile land.

River Pollution:

  1. Causes:
    • Untreated sewage and industrial effluents.
    • Excessive water usage.
  2. Effects:
    • Decline in water quality.
    • Rising pollution reduces self-cleaning capacity.
  3. Examples: Ganga and other rivers facing pollution due to urbanization and industrialization.
  4. Solutions:
    • River cleaning action plans (e.g., Namami Gange Mission).

Extra Knowledge for Competitive Exams:

  • World’s Largest Drainage Basin: Amazon River.
  • India’s Largest Drainage Basin: Ganga.
  • Second Largest Waterfall in India: Shivasamudram (on Kaveri).
  • Biggest Waterfall in India: Jog Falls (on Sharavathi River).

Fun Facts:

  • 97% of Earth’s water is salty; only 3% is freshwater.
  • Most freshwater is trapped as ice.

Activity: Make lists of rivers, basins, and lakes using maps to better understand their geographical location and significance.

THESE ALL ARE THE NOTES OF CHAPTER 3 GEOGRAPHY. AND AFTER SOME TIME YOU GET IMPORTANT QUESTIONS HERE. *#THANKS FOR VISITING, VISIT AGAIN#* 😊