🌊 Class 11 Geography – Chapter 3
Drainage System (जल निकासी तंत्र)
🌧️ Runoff
- The drainage system of any area is influenced by:
- Geological time period 🏞️
- Nature & structure of rocks 🪨
- Topographic slope ⛰️
- Amount & duration of flow of water 💧
👉 Flow of water through channels (नदियाँ व नाले) is called Drainage.
🌍 Drainage System
- Vahika = Rivers, streams & other channels that carry rainwater into lakes, ponds, or oceans.
- The network of these channels = Drainage System (जल निकासी तंत्र).
🌿 Types of Drainage Patterns
- 🌳 Dendritic Pattern – Tree-branch like pattern (e.g., rivers of Northern Plains).
- 🌄 Radial Pattern – Rivers flow outward in all directions from a mountain (e.g., Amarkantak).
- 🔲 Trellis Pattern – Main rivers flow parallel, tributaries join at right angles.
- 🌀 Centripetal Pattern – Rivers flow inward into a lake or trough.
🏔️ Himalayan Drainage System
- Evolved over a long time ⏳
- Major Rivers – Ganga, Brahmaputra, Indus
- Features:
- Perennial (सालभर बहने वाली) – fed by snow + rainfall ❄️🌧️
- Flow through deep gorges ⛰️
- Form V-shaped valleys
- Young rivers → active erosion & waterfall formation
- Create deltas (notably Ganga-Brahmaputra Delta, world’s largest 🌏).
🌊 Rivers of Himalayan Drainage System
🏞️ Indus River System
- One of the largest river basins in the world 🌍
- Area – 11.65 lakh sq. km
- Length – 2880 km (India: 1114 km)
- Westernmost river of Himalayas
- Origin – Bokhar Chu Glacier, Kailash Range (Tibet) 🏔️
- In Tibet = Singi Khamban (Lion Face 🦁)
- Flows NW → passes Ladakh, Baltistan → scenic gorge at Gilgit → enters Pakistan
- Tributaries from Himalayas – Shyok, Gilgit, Zaskar, Hunza, Nubra, Shigar, Gasting, Dras
- Main Tributaries – Jhelum, Chenab, Ravi, Beas, Sutlej
🌊 Jhelum
- Origin – Verinag Spring, Pir Panjal Range (Kashmir)
- Flows via Srinagar & Wular Lake
- Meets Chenab near Jhang (Pakistan).
🌊 Chenab
- Largest tributary of Indus
- Formed by Chandra + Bhaga rivers (at Tandi, Himachal) → also called Chandrabhaga.
🌊 Ravi
- Origin – West of Rohtang Pass, Kullu hills (Himachal)
- Flows via Chamba valley
- Joins Chenab near Sarai Indus (Pakistan).
🌊 Beas
- Origin – Beas Kund, near Rohtang Pass (4000 m)
- Flows through Kullu valley, forms Kati & Largi gorges
- Joins Sutlej near Harike (Punjab).
🌊 Sutlej
- Origin – Rakshas Tal (near Mansarovar, Tibet) – at 4555 m, called Langchen Khambab
- Flows ~400 km parallel to Indus, then enters India at Shipki La Pass
- Important for Bhakra Nangal Project irrigation system 🚰
🌿 Ganga River System
- Most important river of India (basin + cultural importance).
- Origin – Gangotri Glacier (near Gomukh, Uttarkashi, Uttarakhand).
- Known as Bhagirathi till Devprayag.
- At Devprayag – Bhagirathi + Alaknanda → forms Ganga.
- Enters plains at Haridwar → flows south → east → splits into Bhagirathi & Hooghly.
- In Bangladesh – called Padma.
- Length – 2525 km → largest drainage system in India.
- Tributaries:
- Left Bank – Ramganga, Gomti, Ghaghara, Gandak, Kosi, Mahananda.
- Right Bank – Yamuna (longest & westernmost), Son.
🌊 Brahmaputra River System
- One of the largest rivers of the world.
- Origin – Chemayungdung Glacier (near Mansarovar, Kailash).
- In Tibet (1200 km) – called Sangpo (“Purifier”).
- In Arunachal – known as Sisang/Dishang.
- Tributaries: Dibang, Lohit (left bank).
- In Bangladesh – joins Teesta (right bank) → called Jamuna.
- Finally joins Padma → Bay of Bengal.
- Known for floods, erosion & channel shifting.
🏞️ Peninsular Drainage System
- Origin – Western Ghats & Peninsular Plateau.
- Flow mainly west → east (except Narmada & Tapi).
- Older drainage system (compared to Himalayas).
- Features:
- Non-perennial (rain-fed).
- Wide & shallow valleys.
- Mature stage of development.
🔹 Major Rivers
- Mahanadi –
- Origin: Sihawa (Chhattisgarh).
- Length: 851 km.
- Basin: 53% (MP & Chhattisgarh), 47% (Odisha).
- Falls in Bay of Bengal.
- Godavari (Dakshin Ganga) –
- Origin: Nasik (Maharashtra).
- Length: 1465 km (Longest Peninsular river).
- Tributaries: Penganga, Indravati, Pranhita, Manjra.
- Krishna –
- Origin: Mahabaleshwar (Sahyadri).
- Length: 1401 km.
- Tributaries: Koyna, Tungabhadra, Bhima.
- Kaveri –
- Origin: Brahmagiri Hills (Karnataka).
- Length: 800 km.
- Tributaries: Kabini, Bhavani, Amaravati.
- Flows almost all year round.
- Narmada –
- Origin: Amarkantak Plateau (1057 m).
- Creates marble gorge & Dhuandhar Falls (Jabalpur).
- Major project: Sardar Sarovar.
- Joins Arabian Sea near Bharuch.
📊 Drainage Basin Division (By Watershed Area)
- Major River Basins (> 20,000 sq. km) → 14 basins (e.g., Ganga, Brahmaputra, Krishna, Narmada, Tapi).
- Medium River Basins (2,000 – 20,000 sq. km) → 44 basins (e.g., Kalindi, Periyar, Meghna).
- Small River Basins (< 2,000 sq. km) → small rivers in low-rainfall regions.
🌊 River Flow Trend (Regime)
- Himalayan Rivers → Perennial (snow + rainfall).
- Peninsular Rivers → Rain-fed, seasonal fluctuations.
- High flow in monsoon 🌧️
- Dry in summer ☀️
✅ Utility of Rivers
- Irrigation – 33% of annual flow usable 💧.
- Hydropower – Potential of 41 million kW ⚡.
- Navigation – ~10,600 km waterways 🚢.
- Navigable: Ganga, Brahmaputra, Mahanadi, Godavari, Krishna, Narmada, Tapi.
⚠️ Problems of River Water Use
- Inadequate water availability.
- Pollution & silt deposition.
- Seasonal variability.
- Inter-state water disputes.
- Shrinkage of river channels (urbanization).
❌ Why are Indian Rivers Polluted?
- Industrial waste & sewage dumped into rivers.
- Cremation grounds on riverbanks, disposal of ashes & corpses.
- Immersion of idols, flowers during festivals.
- Large-scale bathing, washing of clothes.
✨ Exam Tip:
- Dakshin Ganga = Godavari
- Perennial rivers = Himalayan
- Non-perennial rivers = Peninsular
- World’s largest delta = Ganga-Brahmaputra Delta
