Class 9 Social Science Geography Chapter 3:   Drainage

1. Short Notes for Revision

Basics of Drainage

• Drainage System: Network of streams/rivers draining an area into a larger water body like sea/ocean; small streams join to form main river.
• Drainage Basin: Area drained by a single river and its tributaries; separated by water divide (upland/mountain acting as boundary).
• World’s Largest Basin: Amazon River; in India, Ganga has the largest basin (~8.6 lakh sq km).
• River Course Features: Upper—gorges, V-shaped valleys; Middle—meanders, oxbow lakes; Lower—deltas, floodplains.

Himalayan Rivers

• Characteristics: Perennial (year-round water from rain + snowmelt); long courses (source in Himalayas); intensive erosion in upper reaches; form large deltas.
• Indus River System: Source—Tibet near Mansarovar Lake; enters India in Ladakh (gorge); length—2,900 km; tributaries—Zaskar, Nubra, Shyok, Hunza (Kashmir), Jhelum, Chenab, Ravi, Beas, Satluj (Punjab); drains to Arabian Sea; basin—India (1/3, Ladakh/J&K/HP/Punjab), mostly Pakistan; Indus Water Treaty (1960)—India uses 20% for irrigation.
• Ganga River System: Source—Bhagirathi from Gangotri Glacier + Alaknanda at Devprayag (Uttarakhand); emerges at Haridwar; length—2,525 km; main tributaries—Yamuna (right), Ghaghara, Gandak, Kosi (left, Nepal), Son, Chambal, Betwa, Ken (right); forms Sundarban Delta (world’s largest) with Brahmaputra.
• Brahmaputra River System: Source—Tibet (as Tsangpo); enters India in Arunachal (Dihang); length—2,900 km; tributaries—Dibang, Lohit, Subansiri; floods Assam; joins Ganga in Bangladesh to form delta.

Peninsular Rivers

• Characteristics: Seasonal (rain-dependent, low flow in dry season); shorter/shallower courses; originate in Western Ghats/Central Highlands; fewer tributaries; small deltas/estuaries.
• East Flowing: Flow to Bay of Bengal; major—Mahanadi (Chhattisgarh/Odisha, Hirakud Dam), Godavari (longest peninsular, Maharashtra, Polavaram Project), Krishna (Maharashtra/Karnataka, Almatti Dam), Kaveri (Karnataka/TN, Mettur Dam, disputes).
• West Flowing: Flow to Arabian Sea; Narmada (Rift Valley, Amarkantak source, Marble Rocks/Jabalpur), Tapi (Satpura, Ukai Dam); form estuaries, no deltas.
• River Regime: Fluctuates with monsoon; Himalayan—uniform, Peninsular—peak in summer.

Lakes in India

• Formation Types: Tectonic (Wular—largest freshwater), Lagoon (Chilika—largest brackish), Glacial (Dal), Volcanic (Lonar), Aeolian (Sambhar—largest saltwater).
• Importance: Regulate water flow, moderate climate, tourism (Dal Houseboat), irrigation (Sambhar salt).

River Pollution and Conservation

• Issues: Industrial waste, sewage (Ganga most polluted); Yamuna/Ganga Action Plans (1985, 2015).
• Economic Role: Irrigation (70% agriculture), hydropower, navigation, fisheries; Ganga—holy river.

2. Multiple Choice Questions (MCQs)

1. The area drained by a single river system is known as: A) Water divide B) Drainage basin C) Gorge D) Delta
2. Which of the following is a perennial river? A) Narmada B) Godavari C) Ganga D) Krishna
3. The Indus River originates near: A) Gangotri Glacier B) Lake Mansarovar C) Amarkantak D) Mahabaleshwar
4. According to the Indus Water Treaty (1960), India can use what percent of Indus water? A) 50% B) 20% C) 30% D) 40%
5. The Ganga emerges from the mountains at: A) Rishikesh B) Haridwar C) Devprayag D) Gangotri
6. Which tributary joins the Ganga from the left bank? A) Yamuna B) Son C) Ghaghara D) Chambal
7. The Brahmaputra enters India through: A) Dihang Gorge B) Zoji La Pass C) Nathu La Pass D) Shipki La Pass
8. The longest river in Peninsular India is: A) Kaveri B) Godavari C) Narmada D) Mahanadi
9. Narmada and Tapi flow through: A) Deltas B) Rift valleys C) Gorges only D) Oxbow lakes
10. The largest freshwater lake in India is: A) Chilika B) Wular C) Sambhar D) Dal
11. Which river forms the Sundarban Delta? A) Indus B) Ganga-Brahmaputra C) Godavari D) Narmada
12. Hirakud Dam is on river: A) Ganga B) Mahanadi C) Yamuna D) Krishna
13. The main cause of river pollution in India is: A) Deforestation B) Industrial effluents and sewage C) Soil erosion D) Floods
14. Which lake is a lagoon? A) Wular B) Pulicat C) Lonar D) Bhimtal
15. The Ganga Action Plan was launched in: A) 1985 B) 2000 C) 2015 D) 1975
16. Peninsular rivers are mostly: A) Perennial B) Seasonal C) Snow-fed D) Glacial
17. The Bhagirathi and Alaknanda meet at: A) Haridwar B) Rishikesh C) Devprayag D) Allahabad
18. Which river flows through a rift valley? A) Godavari B) Narmada C) Kaveri D) Brahmaputra
19. Sambhar Lake is famous for: A) Tourism B) Salt production C) Fishing D) Hydropower
20. The world’s largest delta is: A) Nile Delta B) Mississippi Delta C) Sundarban Delta D) Amazon Delta

Answer Key: 1-B, 2-C, 3-B, 4-B, 5-B, 6-C, 7-A, 8-B, 9-B, 10-B, 11-B, 12-B, 13-B, 14-B, 15-A, 16-B, 17-C, 18-B, 19-B, 20-C

3. Very Short Answer Type Questions (VSAQs)

1. Define drainage basin. Answer: Area drained by a river and its tributaries.
2. Name the two major groups of Indian rivers. Answer: Himalayan and Peninsular rivers.
3. What is a perennial river? Answer: River with water throughout the year (rain + snowmelt).
4. Where does the Indus originate? Answer: Near Lake Mansarovar in Tibet.
5. Name one left-bank tributary of Ganga. Answer: Ghaghara.
6. What is the length of Indus River? Answer: 2,900 km.
7. Where do Bhagirathi and Alaknanda meet? Answer: Devprayag.
8. Name the longest Peninsular river. Answer: Godavari.
9. What is the source of Narmada? Answer: Amarkantak Plateau.
10. Which is the largest brackish water lake in India? Answer: Chilika Lake.
11. What is an oxbow lake? Answer: Crescent-shaped lake formed by meandering rivers.
12. Name the treaty governing Indus waters. Answer: Indus Water Treaty (1960).

4. Short Answer Type Questions (SAQs)

1. Differentiate between Himalayan and Peninsular rivers. Answer: Himalayan rivers are perennial with long courses and large deltas, fed by rain and snow; Peninsular rivers are seasonal with shorter courses and small deltas/estuaries, rain-dependent.
2. Describe the Indus River System. Answer: Originates in Tibet, enters India in Ladakh; tributaries include Jhelum, Chenab, Ravi, Beas, Satluj; total length 2,900 km; drains to Arabian Sea; India uses 20% water per 1960 Treaty for irrigation.
3. Explain the course of Ganga River. Answer: Starts as Bhagirathi from Gangotri Glacier, joins Alaknanda at Devprayag; emerges at Haridwar; flows through UP, Bihar, WB; forms Sundarban Delta with Brahmaputra.
4. Why are Peninsular rivers seasonal? Answer: They depend solely on monsoon rainfall, lacking snowmelt; dry season reduces flow in channels, unlike perennial Himalayan rivers.
5. List major tributaries of Brahmaputra. Answer: Dibang, Lohit, Subansiri; it causes floods in Assam due to heavy rainfall and silt.
6. What are the features of west-flowing Peninsular rivers? Answer: Narmada and Tapi flow through rift valleys, form estuaries (no deltas), originate in Central Highlands, shorter courses to Arabian Sea.
7. Why is river pollution a major issue in India? Answer: Untreated sewage and industrial effluents contaminate rivers like Ganga; leads to health hazards, loss of aquatic life; addressed by Action Plans.
8. Describe the importance of lakes. Answer: Lakes like Wular regulate floods, Chilika supports fisheries; they beautify landscapes, aid tourism, and provide water for irrigation.

5. Long Answer Type Questions (LAQs)

1. Compare and contrast Himalayan and Peninsular river systems with examples. Himalayan rivers like Indus, Ganga, Brahmaputra are perennial, originating from snow-fed glaciers, with long courses cutting gorges and forming vast deltas (e.g., Sundarban). They carry heavy silt, creating fertile plains but causing floods. Peninsular rivers such as Godavari, Krishna, Narmada are seasonal, rain-fed from Western Ghats/Highlands, with shorter paths and minimal deltas (estuaries for west-flowing). While Himalayan support dense agriculture via consistent flow, Peninsular aid irrigation via dams (e.g., Hirakud on Mahanadi). Both are vital for economy, but Himalayan face pollution/seismic issues, Peninsular—inter-state disputes.
2. Describe the Ganga River System, its tributaries, and significance. The Ganga, India’s holiest river, originates as Bhagirathi from Gangotri, merging with Alaknanda at Devprayag to form Ganga proper; it emerges at Haridwar, flowing 2,525 km eastward to Bay of Bengal. Right-bank tributaries (Yamuna, Son, Chambal) and left-bank (Ghaghara, Gandak, Kosi from Nepal) join, forming a vast basin covering UP, Bihar, WB. It supports 40% population via fertile alluvial soil, irrigation, and navigation. Culturally sacred (Kumbh Mela), economically key for hydropower/fisheries, but heavily polluted—Ganga Action Plan (1985) aims cleanup. With Brahmaputra, it creates the world’s largest delta, biodiversity hotspot.
3. Discuss the Peninsular rivers, classifying them and highlighting major ones. Peninsular rivers, shorter and rain-dependent, divide into east-flowing (to Bay of Bengal: Mahanadi—Odisha/Chhattisgarh, delta with Chilika; Godavari—’Dakshina Ganga’, longest at 1,450 km, tributaries Pranhita/Indravati; Krishna—drought-prone, Nagarjuna Sagar Dam; Kaveri—disputed, forms island Srirangapatna) and west-flowing (to Arabian Sea: Narmada—rift valley, Dhuandhar Falls; Tapi—parallel, Ukai Dam). They form small deltas east, estuaries west; vital for Deccan agriculture via black soil, but seasonal flow demands reservoirs. Economic role includes rice bowl (Godavari-Krishna), but pollution and water sharing (e.g., Cauvery disputes) challenge sustainability.
4. Explain the causes and effects of river pollution in India, with measures. River pollution stems from untreated sewage (80% urban waste), industrial effluents (textiles/chemicals in Yamuna/Ganga), agricultural runoff (pesticides), and religious practices (immersions). Effects include waterborne diseases (cholera), biodiversity loss (Ganga dolphins endangered), and economic costs (Rs 3 lakh crore annually). Ganga, carrying 1.3 billion liters sewage daily, is worst-hit. Conservation via Namami Gange (2015, Rs 20,000 crore for STPs), Yamuna Action Plan, and laws like Water Act (1974). Community efforts (river linking, awareness) and tech (effluent treatment) are key; sustainable use preserves rivers as lifelines.
5. Elaborate on the types of lakes in India and their distribution. Lakes form via tectonics (Wular—J&K, elongated by earthquakes), volcanic (Lonar—MH, meteor crater), glacial (Dal—Kashmir, houseboats), aeolian (Sambhar—RJ, salt extraction), and lagoons (Chilika—Odisha, largest brackish, migratory birds; Pulicat—AP/TN). Freshwater (Wular, Bhimtal—UK) in north, saltwater (Sambhar) in arid west. They regulate floods (Wular absorbs Jhelum waters), support ecosystems (Irene Lake—birds), and tourism (Nainital). Artificial ones like Gobind Sagar (HP, reservoir) aid hydropower. Distribution: Himalayan north (glacial/tectonic), coastal east (lagoons), peninsular (volcanic/aeolian); vital for water security amid climate change.

6. Source-Based / Case-Based Assessment Questions

Source Extract (from NCERT Figure 3.3 and Text on River Features): “Rivers perform intensive erosional activity in upper courses, carrying silt; in middle/lower, they form meanders, oxbow lakes, and deltas. The Himalayan rivers have long courses, creating depositional features in floodplains. Peninsular rivers, being seasonal, have reduced flow and shallower valleys.”

1. What erosional feature is common in upper river courses? (Factual Recall) Answer: Gorges.
2. Name a depositional feature in lower courses. (Factual Recall) Answer: Delta.
3. Why do Himalayan rivers form large deltas? (Concept Explanation) Answer: Due to heavy silt load from erosion and slowing velocity in plains.
4. How does seasonality affect Peninsular rivers? (Application) Answer: Reduced dry-season flow limits erosion/deposition compared to perennial Himalayan rivers.
5. Infer the impact of meanders on floodplains. (Analytical) Answer: They create fertile alluvial soils for agriculture but increase flood risks.
6. Suggest a conservation measure for delta regions. (Critical Thinking) Answer: Mangrove afforestation to combat erosion and sea-level rise.

Answer Key: (Questions progress from recall to critical analysis; answers as above for exam practice.)

7. Solved Exercise-End Questions (NCERT Solutions)

1. Choose the right answer from the four alternatives given below.

(i) Which one of the following describes the drainage patterns resembling the branches of a tree? (a) Radial (b) Dendritic (c) Centrifugal (d) Trellis Answer: (b) Dendritic (Common in Northern Plains, tree-like branching.)

(ii) In which of the following states is the Wular Lake located? (a) Rajasthan (b) Uttar Pradesh (c) Jammu & Kashmir (d) Punjab Answer: (c) Jammu & Kashmir (Largest freshwater lake, tectonic origin.)

(iii) The river Narmada has its source at: (a) Satpura (b) Amarkantak (c) Brahmagiri (d) Mehsana Answer: (b) Amarkantak (In Madhya Pradesh, flows west in rift valley.)

(iv) Which one of the following lakes is a salt-water lake? (a) Sambhar (b) Dal (c) Wular (d) Gobind Sagar Answer: (a) Sambhar (Largest inland saltwater lake in Rajasthan.)

2. Answer the following questions briefly.

(i) What is meant by a water divide? Provide an example. Answer: Upland separating two drainage basins, e.g., Ambala hills divide Indus and Ganga basins.

(ii) Which is the largest river and the longest river in the world? Answer: Largest basin—Amazon; longest—Nile (6,650 km).

(iii) Name the three major South Indian rivers and the area drained by them. Answer: Godavari (Maharashtra/AP/Telangana, 3.1 lakh sq km), Krishna (MH/KNT/AP, 2.59 lakh sq km), Kaveri (KN/TN, 81,155 sq km).

(iv) State some features of the Ganga delta. Answer: World’s largest (Sundarban), fertile mangrove forests, biodiversity (Royal Bengal Tiger), tidal creeks/distributaries.

(v) Compare the east-flowing and the west-flowing rivers of the Peninsular plateau. Answer: East-flowing: Longer, larger basins, deltas (Godavari/Krishna); West-flowing: Shorter, rift valleys, estuaries (Narmada/Tapi).

3. Describe how the Himalayan and the Peninsular rivers are different from each other.

Answer: Himalayan rivers (Indus/Ganga/Brahmaputra) are perennial (snow/rain-fed), long (2,500+ km), form gorges/deltas, large silt load; Peninsular (Mahanadi/Godavari) are seasonal (rain-fed), short (<1,500 km), shallow valleys/small deltas, fewer tributaries. Himalayan create vast plains; Peninsular support dams but face disputes.

4. Himalayan rivers have their source in the snow-covered areas of the Himalayas. But the Peninsular rivers have their sources in the lesser highlands or peninsulas. Compare the early courses of a Himalayan and a Peninsular river.

Answer: Himalayan upper course: Steep gradients, gorges (e.g., Indus in Ladakh), V-valleys, high erosion. Peninsular: Gentler slopes, broader valleys (e.g., Godavari from Western Ghats), less erosion, waterfalls (e.g., Shivanasamudra on Kaveri).

Map Skills

On an outline map of India, show the following rivers and their tributaries. (i) Indus (ii) Ganga (iii) Brahmaputra (iv) Narmada (v) Tapi (vi) Godavari (vii) Krishna (viii) Mahanadi (ix) Cauvery Answer: (Students mark: Indus—Jhelum/Chenab etc. in NW; Ganga—Yamuna/Son in north-central; Brahmaputra—Lohit in NE; Narmada/Tapi—central-west; Godavari/Krishna/Cauvery/Mahanadi—east peninsular.)

Project/Activity

Find out the extent of the Ganga plain. Locate the towns/cities of the plain that have witnessed the devastating floods of the Ganga. Answer: Ganga Plain—~3.3 lakh sq km (Punjab to WB); flood-prone cities: Patna (Bihar, 2007 floods), Kanpur (UP), Kolkata (WB); causes—siltation, deforestation; mitigation—dams, embankments.