CBSE Class 10 · Social Science · board exam 2027
Chapter 3: Water Resources — notes
The chapter’s 6 parts in the book’s order — the first idea of each and the points Medha Ma’am writes on the board — and the summary at the end. The full lesson and a check question for each part are in the app.
1. Water: A Renewable Resource
Okay, so, you already know three-fourth of the earth is covered with water.
- • Freshwater source: surface run off + groundwater
- • Renewed through the hydrological cycle
- • Water = a renewable resource
- • By 2025: nearly two billion people in absolute water scarcity
- • Reason: variation in seasonal and annual precipitation
2. Causes of Water Scarcity
Okay, so you might think water scarcity only happens in low-rainfall, drought-prone places.
- • Water scarcity caused by: over-exploitation, excessive use, unequal access
- • Irrigated agriculture = largest consumer of water
- • Wells/tube-wells -> falling groundwater levels
- • Industries + urban centres -> pressure on freshwater
- • Even ample water can be scarce if polluted
3. Multi-Purpose River Projects (Dams)
Okay, so people have built dams for a very long time.
- • Dam: barrier across flowing water, creates reservoir/lake
- • Multi-purpose project: irrigation + power + water supply + flood control + navigation + fish breeding
- • Bhakra-Nangal (Sutluj-Beas): hydel power + irrigation
- • Hirakud (Mahanadi): water conservation + flood control
- • Nehru called dams 'temples of modern India'
- • Problems: sedimentation, fragmented rivers, submerged vegetation, salinisation
4. Sardar Sarovar Project
Okay, so let's talk about the Sardar Sarovar Dam.
- • Sardar Sarovar Dam: on Narmada River, Gujarat
- • Covers 4 states: Maharashtra, MP, Gujarat, Rajasthan
- • Irrigates 18.45 lakh hectare in Gujarat (3112 villages, 15 districts)
- • 2,46,000 hectare in Barmer & Jalore (Rajasthan)
- • 37,500 hectare in tribal hilly tract of Maharashtra
- • 75% of Gujarat's command area is drought prone
5. Rainwater Harvesting
Okay, so multi-purpose projects had their problems, remember?
- • Rainwater harvesting: alternative to multi-purpose projects
- • Western Himalayas: 'guls'/'kuls' (diversion channels)
- • Bengal floodplains: inundation channels
- • Rajasthan: 'khadins' (Jaisalmer), 'johads'
- • Rajasthan tanka example: 6.1 m deep, 4.27 m long, 2.44 m wide (Phalodi)
- • Rainwater = 'palar pani', purest form of natural water
- • Tamil Nadu: first state to make rooftop harvesting compulsory
6. Modern Adaptations of Rainwater Harvesting
Even today, rooftop rainwater harvesting continues in many places, though in modern adapted forms.
- • Shillong: rooftop harvesting meets 15-25% of household water needs
- • Gendathur, Mysuru (Karnataka): 200 households with rooftop harvesting
- • Annual precipitation 1,000 mm; 80% collection efficiency; 10 fillings
- • Each house: ~50,000 litres/year; all houses: 1,00,000 litres/year
- • Meghalaya: 200-year-old bamboo drip irrigation system
- • 18-20 litres enters pipe -> reduces to 20-80 drops/minute at plant
Summary
Okay, so let's go back over what we covered today. Water is a renewable resource. It keeps moving, and getting recharged, through the hydrological cycle. Still, water scarcity happens. Mostly it's because of over-exploitation, excessive use, and unequal access — not just low rainfall. Remember that. Then we looked at how people manage and conserve water. Dams have been built since ancient times. Today they're multi-purpose river projects — they give irrigation, power, water supply, flood control, and more. Think of Bhakra-Nangal, Hirakud, and Sardar Sarovar. But these projects bring problems too, like sedimentation, and loss of habitats. Finally, we explored rainwater harvesting — a much older idea. The guls and kuls of the Himalayas, the tankas and khadins of Rajasthan. And these old ideas are still alive today, adapted in places like Shillong, Gendathur, and in Meghalaya's bamboo drip irrigation system. So, tell me — out of all these, which method of conserving water did you find the most clever?
AskMedha · Medha Ma’am — CBSE Class 10 Social Science, Chapter 3. Written from the textbook, checked twice.
Questions parents and students ask
- How do I get the "Water Resources" notes as a PDF?
- Press "Save as PDF" — the phone’s print sheet opens; choose "Save as PDF" there. The PDF holds the notes only.
- Where are these notes written from?
- From the chapter’s own textbook text, part by part, in the book’s own terms; a second, independent model then checked every part against the book. The full lesson, a check question for each part and the practice are in the AskMedha app.
The same preparation, with Medha Ma’am — on your phone
Every question of every chapter with its model answer, practice questions in the board’s own shapes, 60 minutes of class a day, written answers marked, a test every Sunday and a WhatsApp report to parents.
Medha Ma’am is an AI teacher, not a live tutor. Every answer is checked twice; a person takes responsibility.