12 min readConcept sheetSection A MCQ (1 mark), map MCQ and objective (2 marks, two parts); Section B short answer (3 marks), map work (4 marks) and long answer (6 marks)
Drainage: Himalayan and peninsular rivers, and keeping rivers clean
India's rivers form two systems: perennial Himalayan rivers fed by glaciers, and mostly rain-fed peninsular rivers. Pollution threatens both, so people must help keep them clean.
Drainage basinThe area drained by a river and its tributaries
Tributary, delta, estuaryTributary: a stream that joins a larger river (Yamuna). Delta: a triangle of silt at a river mouth (Ganga). Estuary: a river mouth where sea water mixes with river water (Narmada)
Perennial riverA river with water all year round, like the Himalayan rivers fed by snow and glaciers
River clean-up plansGanga Action Plan (GAP) and National River Conservation Plan (NRCP)
Drainage words and the work of rivers
- A drainage system is the flow of surface water, mainly through rivers. It depends on the slope of the land, the rocks, and the amount and speed of water.
- Rivers remove extra water, carry sediment, give water for irrigation and keep up the water table (the level of water under the ground).
- Today rivers also give hydropower, water for industries and places for boating and rafting. So they are called lifelines.
- Many cities stand on rivers: Delhi on the Yamuna, Patna on the Ganga, Guwahati on the Brahmaputra, Nashik on the Godavari and Cuttack on the Mahanadi.
- By origin, Indian rivers form two systems: the Himalayan and the peninsular.
Himalayan and peninsular rivers compared
| Point | Himalayan rivers | Peninsular rivers |
|---|---|---|
| Source | Glaciers and snowy peaks of the Himalayas | Hills of the Western Ghats and the plateau |
| Water | Perennial: snowmelt and rain keep water in them all year | Mostly seasonal: they depend on rain and run low in the dry months |
| Valleys | Cut deep valleys by erosion | Flow in older, shallower valleys |
| Course | Long, meandering (winding in loops) across the plains; courses shift over time | Shorter, with fairly fixed courses |
| Main use | Ideal for irrigation, as they cross fertile plains | Rapids and waterfalls make them good for hydropower |
| Direction and mouth | Indus to the Arabian Sea; Ganga and Brahmaputra to the Bay of Bengal, forming a huge delta | Most flow east into the Bay of Bengal and form deltas; the Narmada and Tapi flow west and form estuaries |
| Main systems | Indus, Ganga, Brahmaputra | Mahanadi, Godavari, Krishna, Kaveri, Narmada, Tapi |
Major rivers at a glance
| River | Origin | Main tributaries | Flows through | Drains into |
|---|---|---|---|---|
| Indus | Tibet, near Lake Mansarovar | Jhelum, Chenab, Ravi, Beas, Satluj | Ladakh, then Pakistan | Arabian Sea |
| Satluj | Tibet, near Lake Mansarovar; enters India at Shipki La | Beas | Himachal Pradesh, Punjab, then Pakistan | Joins the Indus system, to the Arabian Sea |
| Ganga | Gangotri glacier, Uttarakhand (as the Bhagirathi) | Yamuna, Ramganga, Ghaghara, Gomti, Gandak, Kosi, Son | Uttarakhand, Uttar Pradesh, Bihar, West Bengal | Bay of Bengal |
| Brahmaputra | Tibet, near Lake Mansarovar (called the Tsangpo there) | Dibang, Lohit, Tista | Arunachal Pradesh, Assam, then Bangladesh | Bay of Bengal |
| Mahanadi | Near Sihawa, Chhattisgarh | Seonath, Hasdeo, Ib | Chhattisgarh, Odisha | Bay of Bengal |
| Godavari | Trimbakeshwar near Nashik, Maharashtra | Manjra, Wardha, Wainganga, Indravati | Maharashtra, Telangana, Andhra Pradesh | Bay of Bengal |
| Krishna | Near Mahabaleshwar, Maharashtra | Koyna, Bhima, Tungabhadra | Maharashtra, Karnataka, Telangana, Andhra Pradesh | Bay of Bengal |
| Kaveri | Brahmagiri hills (Talakaveri), Karnataka | Kabini, Bhavani, Amaravati | Karnataka, Tamil Nadu | Bay of Bengal |
| Narmada | Amarkantak, Madhya Pradesh | Tawa | Madhya Pradesh, Maharashtra (border), Gujarat | Arabian Sea, through an estuary |
Activity: make your own table of major rivers
- 1Open the physical and the political maps of India in an atlas, side by side.
- 2Draw a table with five columns: river, main tributaries, origin, states it passes through, and where it drains.
- 3Take the seven rivers your lesson names: Ganga, Brahmaputra, Indus, Satluj, Kaveri, Godavari and Krishna.
- 4Trace each river with a finger from its source to its mouth, and write down every state it crosses.
- 5Fill in each row, then check it against the table above.
- 6★Record what you notice: which rivers end in the Bay of Bengal, which in the Arabian Sea, and which flow west.
★ key step
Keeping rivers clean
- India's rivers fall into four groups: Himalayan rivers fed by snow, which never dry up; Deccan rivers that depend on rain; short west-coast rivers, dry for part of the year; and inland rivers of west Rajasthan that end in salt lakes or the sand.
- Over 97 percent of all water on Earth is salty, and most of the rest is frozen in ice caps. Less than 1 percent is fresh water in rivers, lakes, rain and under the ground.
- Many rivers, such as the Ganga and Yamuna, are sacred to millions, yet they are badly polluted.
- Sewage is the largest source of river pollution. Industrial and farm chemicals, garbage and plastic add to it. Polluted water harms aquatic life (water plants and animals) and causes diseases.
- People's indifference worsens the problem, as with the dark, dirty Yamuna in Delhi.
- Water is a state subject, so each state tends to treat a river as its own and ignore effects downstream. Experts want each river treated as one whole.
- The government started the Ganga Action Plan (GAP) and the National River Conservation Plan (NRCP).
- People's role: do not throw garbage, plastic or waste into rivers; save water; practise rainwater harvesting; join local clean-up groups; write to the local authority about pollution.
On the map
- Indus: enters Ladakh from Tibet, flows north-west, then into Pakistan.
- Jhelum, Chenab, Ravi, Beas and Satluj: rivers of Jammu and Kashmir, Himachal Pradesh and Punjab flowing south-west into Pakistan; the Beas joins the Satluj in Punjab.
- Ganga: from Gangotri in Uttarakhand, south-east across Uttar Pradesh, Bihar and West Bengal to the Bay of Bengal.
- Yamuna: from Yamunotri, past Delhi and Agra, joining the Ganga at Prayagraj (Allahabad).
- Ghaghara, Gandak and Kosi: northern tributaries from Nepal that join the Ganga in Bihar.
- Son: southern tributary joining the Ganga near Patna. Chambal: flows north-east across the Malwa plateau to the Yamuna.
- Brahmaputra: enters Arunachal Pradesh from Tibet, flows west through Assam, then south into Bangladesh.
- Mahanadi: from Chhattisgarh east through Odisha to a delta near Cuttack.
- Godavari: from Nashik in Maharashtra, south-east to a delta in Andhra Pradesh.
- Krishna: from Mahabaleshwar in Maharashtra, east through Karnataka, Telangana and Andhra Pradesh.
- Kaveri: from Kodagu in Karnataka, south-east through Tamil Nadu to a delta.
- Narmada: from Amarkantak, west between the Vindhyas and Satpuras to the Gulf of Khambhat. Tapi: south of the Narmada, west to the sea near Surat.
Many towns, from Delhi on the Yamuna to Cuttack on the Mahanadi, drink river water. When you keep garbage and plastic out of a river or canal, you protect the water of every town downstream.
3 marks: “Differentiate between the Himalayan and the peninsular rivers on any three points.” Source: glaciers against plateau hills. Water: perennial against mostly seasonal. Course: long, meandering and shifting against shorter and fixed. Use: irrigation against hydropower. Any three pairs.
2 marks: “What is an estuary? Name one river that forms an estuary.” An estuary is a partly enclosed river mouth where salty sea water mixes with fresh river water. The Narmada (or the Tapi) forms an estuary.
6 marks: “Why are Indian rivers polluted? Suggest ways in which people can help keep them clean.” Causes: sewage, the largest source; industrial and farm chemicals; garbage and plastic; people's indifference; states treating rivers separately. Remedies: GAP and NRCP; treating a river as one whole; treating sewage; rainwater harvesting; not dumping waste; awareness by citizens' groups; writing to local authorities.
Himalayan rivers: snow-fed, all year, wind across the plains. Peninsular rivers: rain-fed, fall in rapids. East-flowing make deltas; Narmada and Tapi make estuaries.