Drainage System and Water Resources of India
Drainage System and Water Resources of India
Rivers give 3 questions and are the most Bihar-relevant part of Indian geography, since the Ganga system dominates the state. The paper asks about the Himalayan and peninsular contrast, about tributaries, and about the projects built on these rivers.
Himalayan and Peninsular Rivers
| Point | Himalayan | Peninsular |
|---|---|---|
| Source | Glaciers and snow | Rainfall |
| Flow | Perennial | Seasonal |
| Course | Long, meandering in plains | Short, fixed |
| Valley | Deep gorges upstream | Shallow |
| Delta or estuary | Large deltas | Both; Narmada and Tapi have estuaries |
| Examples | Indus, Ganga, Brahmaputra | Godavari, Krishna, Kaveri, Mahanadi |
The perennial against seasonal contrast explains why the north faces floods and the peninsula faces water scarcity, and that reasoning is asked more often than the list of names.
The Ganga System
The Ganga rises from the Gangotri glacier as the Bhagirathi, is joined by the Alaknanda at Devprayag, and is joined by the Yamuna at Prayagraj.
| Bank | Tributaries |
|---|---|
| Left bank (north) | Ramganga, Gomti, Ghaghara, Gandak, Burhi Gandak, Bagmati, Kosi, Mahananda |
| Right bank (south) | Yamuna, Son, Punpun, Falgu |
Most of the left-bank tributaries listed join the Ganga inside Bihar, which is why the state has so many rivers for its size. The Son is the largest right-bank tributary, and it meets the Ganga near Patna.
The Ganga and Brahmaputra together form the world's largest delta, the Sundarbans, shared between India and Bangladesh, where the Ganga is known as the Padma.
✗ The Kosi is a right-bank tributary of the Ganga | ✓ It joins from the left, or north, bank — as do the Gandak, Bagmati and Mahananda
The Other Systems
- The Indus rises in Tibet; the Indus Waters Treaty of 1960 divided its waters between India and Pakistan.
- The Brahmaputra is called the Tsangpo in Tibet and the Jamuna in Bangladesh; it carries a very heavy silt load.
- The Godavari is the largest peninsular river and is called the Dakshin Ganga.
- Narmada and Tapi are the notable west-flowing rivers, running through rift valleys and forming estuaries rather than deltas.
- The Kaveri is called the Ganga of the South for its role in Tamil Nadu.
The west-flowing rivers in rift valleys point is the reasoning question: because they flow through a fault trough rather than building up a plain, they carry little silt to the sea and form estuaries, not deltas.
Water Resources and Projects
| Project | River | State |
|---|---|---|
| Bhakra Nangal | Sutlej | Punjab and Himachal |
| Hirakud | Mahanadi | Odisha |
| Nagarjuna Sagar | Krishna | Telangana and Andhra |
| Damodar Valley | Damodar | Jharkhand and West Bengal |
| Kosi Project | Kosi | Bihar and Nepal |
The Kosi Project is the Bihar entry: a barrage and long embankments built with Nepal to control a river that had repeatedly changed course. It reduced but did not end flooding, and the embankments themselves became a subject of debate — which is the honest answer to a question about its success.
Jawaharlal Nehru called such multipurpose projects the temples of modern India, a phrase asked directly. They serve irrigation, power, flood control, navigation and fisheries at once, which is what multipurpose means.
गंगा की उत्तरी सहायक नदियाँ ज्यादातर बिहार में मिलती हैं।
TRE pointer: For a Bihar paper the left-bank and right-bank tributary lists are the highest-value item, since most of the Ganga's northern tributaries join inside the state. The Narmada and Tapi form estuaries, not deltas point is the standard reasoning trap. Temples of modern India and the Kosi Project are the two named items most likely to appear.
60-Second Recap
- Himalayan rivers are perennial and snow-fed; peninsular rivers are seasonal and rain-fed.
- The Ganga rises at Gangotri and meets the Yamuna at Prayagraj.
- Ghaghara, Gandak, Bagmati, Kosi and Mahananda join from the left bank, mostly in Bihar.
- The Son is the largest right-bank tributary, meeting the Ganga near Patna.
- Narmada and Tapi flow west through rift valleys and form estuaries.
- Nehru called multipurpose projects the temples of modern India; the Kosi Project serves Bihar.
Frequently Asked Questions
Which tributaries join the Ganga from the north in Bihar?
The Ghaghara, Gandak, Burhi Gandak, Bagmati, Kamla Balan, Kosi and Mahananda all join from the left or northern bank, mostly within Bihar. They rise in Nepal and the Himalayas and carry heavy silt, which is why north Bihar floods so regularly.
Why do the Narmada and Tapi form estuaries instead of deltas?
Because they flow west through rift valleys, which are fault troughs with steep sides. The confined channel carries little silt to the sea, so no delta builds up at the mouth and the river ends in a funnel-shaped estuary instead.
What is a multipurpose river project?
A dam and reservoir designed to serve several purposes at once: irrigation, hydroelectric power, flood control, navigation and fisheries. Nehru called such projects the temples of modern India. Bhakra Nangal, Hirakud and the Damodar Valley scheme are the standard examples.
Was the Kosi Project successful?
Partly. The barrage and embankments, built jointly with Nepal, reduced the river's tendency to shift course and lessened flooding in some areas. But floods have continued, and the embankments themselves have been criticised for trapping silt and raising the riverbed.