NCERT Class 10 Geography Chapter 3: Water Resources YouTube Lecture Handouts
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NCERT Class 10 Geography Chapter 3: Water Resources
Chapter 3: Water Resources
Why? – Water Wars? ?
“Water, water everywhere nor a drop to drink”
- 3⟋4th World is water – water is renewable
- Why global water scarcity? (by 2025 – 2 billion without water)
- 96.5% in oceans
- 2.5% as freshwater – (of it 70% in icecaps & 30% as groundwater)
- India gets 4% of global rain & ranks 133 in water availability per person per annum
- Total renewable water resources of India are estimated at 1,897 sq km per annum
Why Scarcity?
- Not due to unequal distribution of rain (dry areas of Rajasthan)
- Over- exploitation
- Excessive use
- Unequal access to water among different social groups
- Large population – more demand for water (domestic & agri. use)
- Scarcity even in water abundant areas (like cities)
- Industrialization & Urbanization (ground water pumping devices)
- Bad quality of water – polluted by chemicals, fertilizers & pesticides
- Water stress - when water availability is less than 1,000 m3 per person per day (by Falken Mark)
Multi-Purpose River Projects & Integrated Water Resources Management
- Historical – dams of stone, canal for irrigation
- 1st Century B. C. : Sringaverapura near Allahabad - water harvesting system channeling the flood water of Ganga.
- Chandragupta Maurya: Dams, lakes and irrigation systems were built.
- Irrigation works: Kalinga, (Orissa) , Nagarjunakonda (Andhra Pradesh) , Bennur (Karnataka) , Kolhapur (Maharashtra) , etc.
- 11th Century: Bhopal Lake - one of the largest artificial lakes of its time was built.
- 14th Century: Tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to Siri Fort area.
Dams – Temples of Modern India (JL Nehru)
Dams Classification
- Based on height – large, medium, small
- Based on material - timber, embankment or masonry
Limitations of Damming
- Poor sediment flow
- Excessive sedimentation at the bottom of the reservoir - rockier stream beds and poorer habitats for the rivers aquatic life.
- Fragment rivers – migration of aquatic fauna & spawning gets difficult
- Reservoirs on floodplains - submerge existing vegetation and soil leading to its decomposition
- Farmers move to water intensive crop – salinization
- Rising gap b⟋w rich and poor
- Gives rise to inter-state disputes (allowing Cauvery water⟋Indus water)
- Displacement of local people
- Narmada Bachao Andolan & Tehri Dam Andolan
Ironical Situation
- Made to control floods – but increased floods by sedimentation
- Situation of Gujarat & Maharashtra in 2006 – devastates property & soil erosion
- Sedimentation - flood plains were deprived of silt, natural fertilizer, further adding on to the problem of land degradation.
- Induced earthquakes
- Caused waterborne diseases and pests
- Pollution resulting from excessive use of water
Alternative – Water Harvesting System
- Hill and mountainous regions - Diversion channels like ‘guls’ or ‘kuls’ of Western Himalayas for agriculture.
- Rooftop rain water harvesting - store drinking water in Rajasthan – to tanks⟋tankas 1st rain not collected – Rainwater or Palar Pani - purest water form; also in Shillong
- Shillong so close to Mawsynram – still acute water shortage
- Flood plains of Bengal – Inundation channels to irrigate their fields.
- Arid and semi-arid regions - agricultural fields were converted into rain fed storage structures – water collected and soil moistened - ‘khadins’ in Jaisalmer and ‘Johads’ in Alwar.
- In Rajasthan – rooftop harvesting declined by Rajasthan Canal
- Tamil Nadu - first and the only state in India to make roof top rainwater harvesting structure compulsory to all the houses across the state.
Rooftop Harvesting & Tankas
Bamboo Drip Irrigation System
- 18 - 20 liter water enter bamboo pipe system & reduce to 20 - 80 drops per minute
- In Meghalaya – 200 years old technique
- From springs on hilltop to low level by gravity
- Fertilizers can be used with high efficiency
- Water used at maximum level
- Low operation cost
- Low initial cost
- Weed cannot absorb water
- Maximum crop yield
- Nutrient loss is minimized
- Can pass through road
✍ Manishika