Drainage Patterns and the Indus System
NCERT Class 9 - Contemporary India I, Chapter 3 • NCERT Class 11 - India Physical Environment
Drainage Patterns and the Indus System
The area drained by a river and its tributaries is a drainage basin, and the upland separating two basins is a water divide. India's rivers fall into two great groups - the Himalayan rivers, fed by snow and rain, and the peninsular rivers, fed by rain alone.
Drainage patterns
| Pattern | Shape and cause |
|---|---|
| Dendritic | Like the branches of a tree, where the slope is uniform and the rock uniformly resistant |
| Trellis | Tributaries join the main stream at right angles, where hard and soft rock alternate in parallel bands |
| Rectangular | Streams turn at sharp angles, following a network of joints and faults |
| Radial | Streams flow outward in all directions from a central dome or peak |
| Centripetal | Streams converge inward into a basin or depression |
- Rivers that existed before the mountains rose and cut down as fast as the land rose are called antecedent; the Indus, Satluj and Brahmaputra cut deep gorges across the Himalayas for this reason.
- The Ambala upland is the water divide between the Indus and the Ganga systems, and the Delhi ridge is another familiar divide.
Himalayan and peninsular rivers compared
| Point | Himalayan rivers | Peninsular rivers |
|---|---|---|
| Source of water | Snow, glaciers and rain | Rain only |
| Flow | Perennial | Largely seasonal, shrinking in the dry season |
| Stage of valley | Youthful, still cutting down | Mature, with broad shallow valleys |
| Course | Meandering and often shifting | Fixed, with almost no meandering |
| Catchment | Very large basins | Smaller basins |
| Delta | Large deltas, since they carry much silt | Small deltas or estuaries |
- Peninsular rivers flow over hard rock in nearly fixed courses, which is why they are well suited to dam sites and hydroelectric projects, while Himalayan rivers flowing on soft alluvium shift course and cause floods.
The Indus system
- The Indus rises near Lake Mansarovar in Tibet, flows north-west, enters India in Ladakh, and is about 2,900 kilometres long, making it one of the longest rivers in the world.
- In Ladakh its tributaries include the Zaskar, Nubra, Shyok and Hunza.
- Its five great Punjab tributaries are the Jhelum, Chenab, Ravi, Beas and Satluj, which join and enter the Indus near Mithankot in Pakistan.
| Tributary | Source and note |
|---|---|
| Jhelum | Rises at Verinag in Kashmir and flows through the Wular lake |
| Chenab | The largest tributary, formed by the union of the Chandra and Bhaga |
| Ravi | Rises in the Kullu hills near the Rohtang pass |
| Beas | Rises near the Rohtang pass and flows entirely within India |
| Satluj | Rises in Tibet near Mansarovar, an antecedent river crossing the Himalayas |
- Under the Indus Waters Treaty of 1960, India has full use of the three eastern rivers - Ravi, Beas and Satluj - while Pakistan has the three western rivers - Indus, Jhelum and Chenab - on which India retains limited non-consumptive rights.
हिंदी संकेत: व्यास एकमात्र ऐसी बड़ी सहायक नदी है जो पूरी तरह भारत में बहती है। सिंधु जल संधि में पूर्वी नदियां भारत को और पश्चिमी नदियां पाकिस्तान को मिलीं।
Exam me kaise aata hai
Match-the-following on river and its source is very common. Factual questions ask which is the largest tributary of the Indus and which rivers are antecedent. Statement-based questions compare Himalayan and peninsular rivers.
UPSC / State PSC ke liye
Note the reason antecedent rivers matter - they prove that the rivers are older than the present height of the Himalayas, which supports the account of a slowly rising range. For the treaty, the analytical point is that India's limited use of the western rivers is a non-consumptive right, not a bar on all use.
Yahan confuse hote hain
✗ The Satluj rises in India | ✓ It rises in Tibet near Mansarovar and is an antecedent river
✗ Peninsular rivers are perennial | ✓ They are largely seasonal; Himalayan rivers are perennial
✗ Under the treaty India got the western rivers | ✓ India got the eastern rivers - Ravi, Beas and Satluj
Ek nazar me
- Drainage patterns - dendritic, trellis, rectangular, radial and centripetal.
- Indus, Satluj and Brahmaputra are antecedent rivers cutting across the Himalayas.
- Himalayan rivers are perennial and youthful; peninsular rivers are seasonal and mature.
- The Indus rises near Lake Mansarovar and enters India in Ladakh.
- Its five Punjab tributaries are the Jhelum, Chenab, Ravi, Beas and Satluj.
- The Chenab is the largest tributary; the Beas flows entirely within India.
- The Indus Waters Treaty of 1960 gave India the eastern rivers and Pakistan the western.