DRAINAGE SYSTEM OF INDIA

BASIC CONCEPTS

• A river drains the water collected from a specific area called its catchment area.
• The flow of water through well-defined channels is called drainage.
• The network of such channels is known as a drainage system.
• The boundary separating two drainage basins is called a watershed.

BASIS OF CLASSIFICATION OF INDIAN DRAINAGE

I. ON THE BASIS OF ORIENTATION TO THE SEA

1. ARABIAN SEA DRAINAGE (About 23% area)
• Major rivers:
  - Indus
  - Narmada
  - Tapi
  - Mahi
  - Periyar

2. BAY OF BENGAL DRAINAGE (About 77% area)
• Major rivers:
  - Ganga
  - Brahmaputra
  - Mahanadi
  - Godavari
  - Krishna
  - Kaveri
• These two systems are separated by:
  - Delhi Ridge
  - Aravalli
  - Sahyadri (Western Ghats)

II. ON THE BASIS OF SIZE OF CATCHMENT

1. MAJOR RIVER BASINS (More than 20,000 sq km)
• Total 14 basins including:
  - Ganga, Brahmaputra, Krishna, Tapi, Narmada, Mahi, Pennar, Sabarmati, Barak etc.

2. MEDIUM RIVER BASINS (2,000 to 20,000 sq km)
• About 44 basins including:
  - Kalindi, Periyar, Meghna etc.

3. MINOR RIVER BASINS (Less than 2,000 sq km)
• Mostly found in low rainfall regions.

III. ON THE BASIS OF ORIGIN AND NATURE

• Himalayan Drainage
• Peninsular Drainage

DRAINAGE PATTERNS

• Dendritic Pattern: Tree-like pattern. Example: Rivers of Northern Plains.
• Radial Pattern: Rivers flow in all directions from a central highland. Example: Amarkantak.
• Trellis Pattern: Main rivers flow parallel and tributaries join at right angles.
• Centripetal Pattern: Rivers flow towards a lake or depression.

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THE HIMALAYAN DRAINAGE SYSTEM
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• Includes:
  - Indus
  - Ganga
  - Brahmaputra systems
• These rivers are perennial.
• They are fed by:
  - Glacier melt
  - Rainfall

CHARACTERISTICS OF HIMALAYAN RIVERS

• Cut deep gorges in mountains.
• Form V-shaped valleys, rapids and waterfalls.
• In plains, they form:
  - Flood plains
  - Meanders
  - Oxbow lakes
  - Braided channels
  - Deltas
• Kosi is famous for frequent shifting of course and is called “Sorrow of Bihar”.

EVOLUTION OF HIMALAYAN DRAINAGE

• Geologists believe that a mighty river called Indo-Brahma once flowed along the Himalayas.
• During Miocene period (5–24 million years ago), it was broken into:
  - Indus system (west)
  - Ganga system (central)
  - Brahmaputra system (east)
• Causes:
  - Uplift of Potwar Plateau (Delhi Ridge) separating Indus and Ganga.
  - Down-thrusting of Malda Gap diverting Ganga and Brahmaputra towards Bay of Bengal.

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THE INDUS RIVER SYSTEM
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• Origin:
  - Near Bokhar Chu glacier in Tibet (Kailash range).
• In Tibet known as:
  - Singi Khamban or Lion’s mouth.
• Flows between:
  - Ladakh and Zanskar ranges.
• Enters Pakistan near Chillar.
• Meets Kabul river near Attock.
• In India, it flows only through:
  - Leh district of Ladakh.

MAJOR TRIBUTARIES

1. JHELUM
• Origin: Verinag spring (Pir Panjal).
• Flows through Srinagar and Wular Lake.
• Joins Chenab near Jhang.

2. CHENAB
• Largest tributary.
• Formed by:
  - Chandra and Bhaga at Tandi.
• Also called Chandrabhaga.
• Length: about 1180 km.

3. RAVI
• Origin: Near Rohtang Pass.
• Flows through Chamba valley.
• Joins Chenab in Pakistan.

4. BEAS
• Origin: Beas Kund near Rohtang.
• Flows through Kullu valley.
• Joins Satluj near Harike.

5. SATLUJ
• Origin: Rakas Lake near Mansarovar (Tibet).
• Known as Langchen Khambab in Tibet.
• An antecedent river.
• Feeds Bhakra Nangal Project canal system.

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THE GANGA RIVER SYSTEM
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• Origin:
  - Gangotri glacier near Gaumukh (Uttarakhand).
• Length: 2525 km.
• States covered:
  - Uttarakhand, UP, Bihar, West Bengal.
• Enters plains at Haridwar.
• Splits into:
  - Bhagirathi and Hugli.
• Empties into Bay of Bengal near Sagar Island.

MAJOR TRIBUTARIES

• Yamuna (longest tributary)
  - Origin: Yamunotri glacier.
  - Chambal is its important tributary.
• Gandak
  - Formed by Kaligandak and Trishulganga.
  - Joins Ganga near Sonpur.
• Ghaghara
  - Origin: Mapchachungo glacier.
  - Joined by Sarda.
• Kosi
  - Antecedent river.
  - Called Sapta Kosi.
• Ramganga
  - Joins Ganga near Kannauj.
• Son
  - Origin: Amarkantak.
  - Joins near Arrah.
• Damodar
  - Joins Hugli.
  - Earlier called Sorrow of Bengal.
• Mahananda
  - Last left bank tributary.

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THE BRAHMAPUTRA RIVER SYSTEM
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• Origin:
  - Chemayungdung glacier near Mansarovar.
• In Tibet called:
  - Tsangpo.
• Cuts deep gorge near Namcha Barwa.
• Enters India as:
  - Siang or Dihang.
• In Bangladesh known as:
  - Jamuna.
• Joins Padma and falls into Bay of Bengal.

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THE PENINSULAR DRAINAGE SYSTEM
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• Older than Himalayan system.
• Rivers have:
  - Broad valleys
  - Mature stages
• Most rivers flow eastwards.
• Exceptions:
  - Narmada and Tapi (west flowing)

CHARACTERISTICS

• Fixed course
• Absence of meanders
• Non-perennial (seasonal)

EVOLUTION OF PENINSULAR DRAINAGE

• Three major events:
  1. Submergence of western flank disturbed symmetry.
  2. Faulting created Narmada and Tapi rift valleys.
  3. Tilting of plateau directed rivers towards Bay of Bengal.

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RIVERS FLOWING INTO BAY OF BENGAL
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• Mahanadi
  - Origin: Sihawa, Chhattisgarh.
• Godavari (Dakshin Ganga)
  - Origin: Nasik.
  - Largest peninsular river.
• Krishna
  - Origin: Mahabaleshwar.
• Kaveri
  - Origin: Brahmagiri hills.
  - Perennial due to dual monsoon rainfall.

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RIVERS FLOWING INTO ARABIAN SEA
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• Narmada
  - Origin: Amarkantak.
  - Rift valley river.
  - Forms estuary near Bharuch.
• Tapi
  - Origin: Multai, MP.
• Luni
  - Largest river of Rajasthan west of Aravalli.
  - Ephemeral river.
• Other small rivers:
  - Sabarmati, Mahi, Periyar, Bharathapuzha, Sharavati, Mandovi, Zuari etc.

IMPORTANT FACT

• Mahi river crosses Tropic of Cancer twice.

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CONCLUSION

• Indian drainage system reflects:
  - Geological history
  - Relief structure
  - Climatic conditions
• It plays a vital role in:
  - Agriculture
  - Settlement
  - Civilization
  - Economic development

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Subject: Geography

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