Contemporary India – II | Class X | Chapter 3
🌊 WATER RESOURCES
Notes • Answers • Worksheet
📌 Quick Navigation
- Part A: Notes – Water Scarcity, Dams, Rainwater Harvesting
- Part B: All Answers – Intext + Exercise 1, 2, 3
- Part C: Worksheet – Practice Questions
📖 PART A: NOTES
1. Water as a Resource
- 3/4 of Earth is covered with water — but only a small proportion is usable freshwater.
- Freshwater comes from surface run-off and groundwater — both continuously recharged by the hydrological cycle.
- Water is a renewable resource because it moves within the hydrological cycle (evaporation → condensation → precipitation).
- Despite this, by 2025 nearly 2 billion people are predicted to face absolute water scarcity.
🔄 The Hydrological Cycle (Why Water is Renewable)
☁️ Precipitation
(Rain/Snow)
(Rain/Snow)
→
🏔️ Surface Run-off
(Rivers/Streams)
(Rivers/Streams)
→
🌱 Groundwater
(Absorbed by soil)
(Absorbed by soil)
→
💧 Ocean/Lakes
→
☀️ Evaporation
(Water vapour rises)
(Water vapour rises)
→
☁️ Back to Clouds
2. Water Scarcity
| Type | Meaning | Example |
|---|---|---|
| Quantitative Scarcity | Not enough water physically available | Rajasthan deserts, drought areas |
| Qualitative Scarcity | Water exists but is polluted/unsafe | Cities with industrial/sewage pollution |
Main Causes:
- Over-exploitation & excessive use of water
- Unequal access among social groups
- Large & growing population (more food → more irrigation)
- Rapid industrialisation — industries are heavy water users
- Urbanisation — groundwater pumping by housing societies
- Pollution by domestic/industrial wastes, pesticides, fertilisers
Government Initiatives:
| Scheme | Goal |
|---|---|
| Jal Jeevan Mission (JJM) | 55 litres/person/day potable piped water to every rural household |
| Atal Bhujal Yojana (Atal Jal) | Water conservation in 8220 water-stressed gram panchayats in 7 states (Gujarat, Haryana, Karnataka, MP, Maharashtra, Rajasthan, UP) |
3. Multi-Purpose River Projects & Dams
📌 What is a Dam?
A barrier across flowing water that obstructs/directs/retards flow, creating a reservoir or lake. "Dam" technically refers to the reservoir. Dams are classified by structure (timber/embankment/masonry) or height (low/medium/high).🏗️ Uses of Multi-Purpose Projects
🌾 Irrigation
⚡ Hydel Power
🏠 Domestic Water Supply
🏭 Industrial Use
🌊 Flood Control
🐟 Fish Breeding
⛵ Navigation
🏖️ Recreation
Major Projects:
| Project | River/Location | Key Feature |
|---|---|---|
| Bhakra-Nangal | Sutluj-Beas basin | Hydel power + Irrigation |
| Hirakud | Mahanadi, Odisha | Water conservation + Flood control |
| Sardar Sarovar | Narmada, Gujarat | Covers 4 states; irrigation for drought-prone areas; 18.45 lakh hectares |
💬 Jawaharlal Nehru called dams the "Temples of Modern India" — they would integrate agricultural development with rapid industrialisation.
Disadvantages:
- Disrupts natural river flow → poor sediment flow → rockier stream beds → harms aquatic life
- Fragments rivers → fish cannot migrate/spawn
- Submerges forests, vegetation, soil → ecological damage
- Sediment in reservoirs can trigger floods (ironic!)
- Flood plains lose silt (natural fertiliser) → land degradation
- Can induce earthquakes & spread water-borne diseases
- Irrigation → salinisation of soil
- Large-scale displacement of people from reservoir areas
- Cause inter-state water disputes (e.g., Krishna-Godavari dispute)
4. Rainwater Harvesting
Ancient India had a rich tradition of water harvesting long before modern dams. People adapted methods to local ecology, rainfall, and soil types.
| Method | Region | Description |
|---|---|---|
| Guls / Kuls | Western Himalayas | Diversion channels from streams for agriculture on hill slopes |
| Rooftop + Tanka | Rajasthan (Bikaner, Phalodi, Barmer) | Rainwater stored in underground tanks (tankas) for drinking |
| Inundation Channels | Bengal flood plains | Channels irrigate fields using flood water |
| Khadins | Jaisalmer, Rajasthan | Fields converted to rain-fed storage structures; water moistens soil |
| Johads | Other parts of Rajasthan | Traditional tanks/ponds to store rainwater |
| Bamboo Drip | Meghalaya | 200-year-old system; bamboo pipes carry spring water to plant roots |
🏡 How the Tanka (Rooftop Harvesting) System Works
🌧️ Rain falls on Rooftop
→
🔧 PVC / Clay Pipe
(1st shower skipped to clean pipes)
(1st shower skipped to clean pipes)
→
🏺 Underground Tanka
(Filtered with sand & bricks)
(Filtered with sand & bricks)
→
💧 Pure 'Palar Pani'
(Drinking water till next rain)
(Drinking water till next rain)
Modern Adaptations:
| Place | Achievement |
|---|---|
| Gendathur, Karnataka | 200 households; ~50,000 litres/house/year; 80% collection efficiency; "rich in rainwater" village |
| Shillong, Meghalaya | 15–25% of household water from rooftop harvesting; despite highest rainfall at Cherapunjee 55 km away! |
| Tamil Nadu | First state to make rooftop harvesting compulsory; legal penalties for defaulters |
| PM Krishi Sinchayee Yojana | "Har khet ko pani, per drop more crop" — efficient irrigation & sustainable water conservation across India |
🏛️ Ancient Hydraulic Structures
- 1st century BC – Sringaverapura (Allahabad): channelled Ganga floodwater
- Chandragupta Maurya – Extensive dams, lakes, irrigation systems
- 11th Century – Bhopal Lake (one of the largest artificial lakes of its time)
- 13th–14th Century – Hauz Khas tank, Delhi, built by Allauddin Khilji for Siri Fort
✅ PART B: ALL ANSWERS
Intext Activity Answers
💬 Write a short proposal on how you can conserve water.
Ans: We can conserve water by: (1) fixing leaking taps immediately, (2) using a bucket instead of shower, (3) reusing water from washing vegetables to water plants, (4) installing rooftop rainwater harvesting at home, (5) spreading awareness about not wasting water in our community. The key is to change our attitude from consumption to conservation.
💬 Find out about one traditional method of building dams/irrigation works.
Ans: Hauz Khas Tank, Delhi (13th–14th century): Built by Allauddin Khilji to supply water to the Siri Fort area. It is one of the earliest examples of planned urban water management in India — a large reservoir that stored rainwater and was used for drinking and irrigation in the city.
Exercise 1: Multiple Choice Questions
(i) Water Scarcity Classification:
| Situation | Classification | Reason |
|---|---|---|
| (a) High annual rainfall | ✅ NOT suffering | Enough water available |
| (b) High rainfall + large population | ⚠️ SUFFERING | Over-exploitation due to large demand |
| (c) High rainfall + highly polluted water | ⚠️ SUFFERING | Qualitative scarcity — water unusable |
| (d) Low rainfall + low population | ✅ NOT suffering | Low demand matches low supply |
(ii) Which statement is NOT an argument in favour of multi-purpose river projects?
Ans: (c) Multi-purpose projects lead to large scale displacements and loss of livelihood.
This is a disadvantage, not a benefit. Options (a), (b), and (d) are all genuine advantages.
This is a disadvantage, not a benefit. Options (a), (b), and (d) are all genuine advantages.
(iii) Correct the False Statements:
(a) Urban centres have helped in proper utilisation of water resources.
Correct Statement: Multiplying urban centres with large and dense populations and urban lifestyles have NOT helped — they have added to water and energy requirements and further aggravated the problem of water scarcity.
(b) Damming rivers does not affect natural flow and sediment flow.
Correct Statement: Regulating and damming rivers DOES affect their natural flow. It causes poor sediment flow, excessive sedimentation at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for aquatic life.
(c) Rooftop rainwater harvesting in Rajasthan has gained popularity despite high water availability due to Indira Gandhi Canal.
Correct Statement: The practice is ON THE DECLINE in western Rajasthan as plenty of water is available from the perennial Indira Gandhi Canal. However, some houses still maintain the tankas as they do not like the taste of tap water.
Exercise 2: Short Answer (30 words)
(i) How does water become a renewable resource?
Ans: Water moves continuously within the hydrological cycle — evaporation from oceans, condensation into clouds, precipitation as rain/snow, and recharge of surface run-off and groundwater. This cycle ensures water is constantly renewed and hence a renewable resource.
(ii) What is water scarcity and its main causes?
Ans: Water scarcity = not having enough usable water to meet human needs.
Main causes: Over-exploitation, excessive use, unequal access, growing population, industrialisation, expansion of irrigated agriculture, and pollution of available water sources.
Main causes: Over-exploitation, excessive use, unequal access, growing population, industrialisation, expansion of irrigated agriculture, and pollution of available water sources.
(iii) Advantages vs. Disadvantages of multi-purpose river projects.
✅ Advantages: Irrigation, hydroelectric power, domestic & industrial water supply, flood control, inland navigation, fish breeding, recreation.
❌ Disadvantages: Disrupts natural river flow, excessive sedimentation, aquatic life harmed, submerges forests, can trigger floods, land degradation (loss of silt), displaces people, causes earthquakes and diseases, inter-state disputes, salinisation of soil.
❌ Disadvantages: Disrupts natural river flow, excessive sedimentation, aquatic life harmed, submerges forests, can trigger floods, land degradation (loss of silt), displaces people, causes earthquakes and diseases, inter-state disputes, salinisation of soil.
Exercise 3: Long Answer (120 words)
(i) How is rainwater harvesting carried out in semi-arid Rajasthan?
Ans: In semi-arid regions of Rajasthan (Bikaner, Phalodi, Barmer), almost all houses traditionally had underground tankas for storing drinking water. These were built inside the main house or courtyard and connected to sloping rooftops via pipes. Rainwater from the rooftop flowed down the pipe into the tanka. The first spell of rain was not collected (to clean pipes and roof). Subsequent rains were stored. Tankas could be very large — one in Phalodi was 6.1m deep, 4.27m long, 2.44m wide. The stored water, called 'palar pani', was considered the purest form of natural water. It could sustain a household till the next rainfall, especially in summers. Other methods include khadins in Jaisalmer (fields as storage structures) and johads (traditional tanks) across Rajasthan.
(ii) How are traditional rainwater harvesting methods being modernised?
Ans: Traditional methods are being successfully adapted across India: (1) Gendathur, Karnataka: 200 households installed rooftop rainwater harvesting; annual precipitation is 1000 mm; with 80% collection efficiency and ~10 fillings, each house collects ~50,000 litres/year; total village harvest = 1,00,000 litres/year. (2) Shillong, Meghalaya: Almost every household has a rooftop system meeting 15–25% of water needs. Notably, Cherapunjee (55 km away) gets the highest rainfall in the world, yet Shillong faces acute water shortage — showing the importance of harvesting. (3) Tamil Nadu: First state to make rooftop harvesting compulsory by law, with penalties for defaulters. (4) Bamboo Drip Irrigation, Meghalaya: 200-year-old system using bamboo pipes to channel spring water over hundreds of metres to plant roots. (5) PM Krishi Sinchayee Yojana: National programme promoting "har khet ko pani" and "per drop more crop" — efficient on-farm water use and sustainable water conservation.
📝 PART C: WORKSHEET
Name: Class: Date:
Section 1: Fill in the Blanks
- Three-fourths of earth's surface is covered with .
- Freshwater is mainly obtained from run-off and .
- The largest consumer of water is agriculture.
- Bhakra-Nangal project is located in the river basin.
- Hirakud dam is built on the river.
- Underground tanks for storing rainwater in Rajasthan are called .
- Rainwater is called ' pani' in Rajasthan and considered the purest form.
- was the first state to make rooftop rainwater harvesting compulsory.
- The Drip Irrigation System of Meghalaya is about 200 years old.
- Jal Jeevan Mission aims to provide litres per person per day.
Section 2: True or False
- Water scarcity only occurs in drought-prone areas.
- Irrigated agriculture is the largest consumer of water.
- Dams always help in controlling floods effectively.
- Palar pani is considered the purest form of natural water.
- Gendathur village in Karnataka is famous for rooftop rainwater harvesting.
Section 3: Match the Following
| Column A | Column B |
|---|---|
| 1. Bhakra-Nangal | A. Flood control + Water conservation |
| 2. Hirakud Dam | B. Hydel power + Irrigation (Sutluj-Beas) |
| 3. Sardar Sarovar | C. Diversion channels for agriculture (guls/kuls) |
| 4. Western Himalayas | D. Narmada River, Gujarat (4 states) |
| 5. Hauz Khas Tank | E. Built by Allauddin Khilji for Siri Fort |
Answers: 1–, 2–, 3–, 4–, 5–
Section 4: Short Answer Questions
- Why can a region with high rainfall still face water scarcity?
- What did Jawaharlal Nehru say about dams and why?
- What is the Atal Bhujal Yojana? Name any two states covered under it.
- Why is the first spell of rain not collected in the tanka system?
Section 5: Map Work
On a blank map of India, locate and label the following dams:
📍 Bhakra-Nangal (Punjab)
📍 Hirakud (Odisha)
📍 Sardar Sarovar (Gujarat)
📍 Nagarjuna Sagar (Andhra Pradesh)
📍 Mettur (Tamil Nadu)
📍 Periyar (Kerala)
Answer Key:
Fill in the Blanks: 1-water 2-surface/groundwater 3-irrigated 4-Sutluj-Beas 5-Mahanadi 6-tankas 7-palar 8-Tamil Nadu 9-Bamboo 10-55
True/False: 1-False 2-True 3-False 4-True 5-True
Match: 1-B 2-A 3-D 4-C 5-E
Fill in the Blanks: 1-water 2-surface/groundwater 3-irrigated 4-Sutluj-Beas 5-Mahanadi 6-tankas 7-palar 8-Tamil Nadu 9-Bamboo 10-55
True/False: 1-False 2-True 3-False 4-True 5-True
Match: 1-B 2-A 3-D 4-C 5-E
Chapter 3: Water Resources | Contemporary India – II | Class X | NCERT