Class 10 Social Science Notes — Chapter 7: Water Resources
Availability, use, dams and rainwater harvesting.
Detailed NCERT notes
- Freshwater sources: precipitation, surface run-off, groundwater. Only ~2.5% of Earth's water is freshwater; most locked in glaciers.
- Water scarcity in India due to over-exploitation, unequal access, pollution and rising demand for irrigation and industry.
- Multipurpose dams: designed to store water, generate hydroelectric power, control floods, aid irrigation, provide drinking water, support inland navigation.
- Examples: Bhakra Nangal (Sutlej), Sardar Sarovar (Narmada), Hirakud (Mahanadi), Damodar Valley Project.
- Nehru called dams the 'temples of modern India'.
- Criticisms of large dams: submerge fertile land and forests, displace people (especially tribals), disrupt ecosystems, sediment build-up, unequal water distribution, inter-state disputes, changes in aquatic life.
- Narmada Bachao Andolan (NBA) — Medha Patkar-led protest against Sardar Sarovar Dam due to displacement of tribal communities and ecological damage.
- Rainwater harvesting: capturing rain locally for direct use or groundwater recharge. Old techniques include tanks in Rajasthan (kul, kund, tanka), johads, bamboo drip irrigation in Meghalaya, guls in Himachal, ahars/pynes in Bihar.
- Rooftop rainwater harvesting: common in Meghalaya (Shillong) and mandatory in some states like Tamil Nadu (Chennai model).
- Interlinking of rivers, drip and sprinkler irrigation, and treatment of urban wastewater are modern strategies.
Formulas & key results
Mind map
- Scarcity causes → multipurpose dams → criticisms
- Rainwater harvesting: traditional + modern
- Case studies: NBA, Chennai rooftop harvesting
Tricks & shortcuts
- Bhakra Nangal → Sutlej; Sardar Sarovar → Narmada; Hirakud → Mahanadi.
- Meghalaya → bamboo drip irrigation.
Common mistakes to avoid
- Ignoring social costs of large dams.
- Confusing tank irrigation regions.
Competency-based questions & answers
- Q. Why did the Narmada Bachao Andolan oppose the Sardar Sarovar dam?A. Displacement of tribal communities without adequate rehabilitation, ecological damage, submergence of forests and unequal distribution of benefits between farmers and industries.
- Q. How can rooftop rainwater harvesting help urban India?A. Recharges groundwater, reduces flooding, provides domestic water in dry months, and reduces stress on piped supply — Chennai's mandatory rule shows measurable gains.