Class 12 Geography Notes Chapter 6 (Water resources) – India - People and Economy Book
Alright students, let's get straight into Chapter 6, 'Water Resources', from your 'India: People and Economy' textbook. This is a crucial chapter, not just for your exams but also for understanding one of the most critical challenges facing India today. Pay close attention to the data points and concepts.
Chapter 6: Water Resources - Detailed Notes for Exam Preparation
1. Introduction: Water Scarcity and Importance
- Water is an indispensable resource for life, agriculture, industry, and ecosystems.
- India accounts for about 2.45% of the world's surface area, 4% of the world's water resources, but supports about 16% of the world's population.
- This disparity leads to significant pressure on water resources.
- Per capita water availability is dwindling continuously due to population growth and increasing demand. India is considered a water-stressed region.
2. Water Resources of India
India's water resources can be broadly categorised into:
-
A. Surface Water Resources:
- Comprises water in rivers, lakes, ponds, and tanks.
- There are four major sources: rivers, lakes, ponds, and tanks.
- India has numerous rivers, classified into major, medium, and minor river basins.
- Major River Basins: Ganga, Brahmaputra, Barak, Indus, Godavari, Krishna, Mahanadi, Narmada, Tapi, Kaveri, Pennar, Sabarmati, Mahi, etc.
- Mean annual flow in all river basins in India is estimated to be 1,869 cubic kilometers (cu km).
- However, only about 690 cu km (32%) of this surface water can be utilised due to topographical, hydrological, and other constraints.
- Ganga, Brahmaputra, and Barak rivers, although accounting for only about one-third of the total river basin area, hold about 60% of the total surface water resources. Their potential is largely under-utilised compared to rivers in peninsular India (like Godavari, Krishna, Kaveri) where utilisation is much higher.
-
B. Groundwater Resources:
- Water stored beneath the earth's surface in aquifers.
- Total replenishable groundwater resources in India are about 432 cu km.
- The Ganga and Brahmaputra basins have about 46% of the total replenishable groundwater resources.
- Level of Groundwater Utilisation:
- Is relatively high in the river basins of north-western India (Punjab, Haryana, Rajasthan) and parts of South India (Tamil Nadu). Utilisation exceeds replenishment in some areas.
- States like Punjab, Haryana, Rajasthan, and Tamil Nadu have very high groundwater utilisation (often >100% of recharge).
- States like Chhattisgarh, Odisha, Kerala utilise only a small proportion of their groundwater potential.
- States like Gujarat, Uttar Pradesh, Bihar, Tripura, Maharashtra are utilising their groundwater resources at a moderate rate.
- Future development potential exists in states with lower utilisation, but sustainable practices are crucial.
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C. Lagoons and Backwaters:
- India has a vast coastline; states like Kerala, Odisha, and West Bengal have numerous lagoons and lakes.
- Water is generally brackish (salty).
- Used for fishing, irrigating certain paddy varieties (coconut groves in Kerala), navigation.
3. Water Demand and Utilisation
- Dominant Use: Agriculture accounts for the largest share of both surface water (89%) and groundwater (92%) utilisation.
- Other Uses: Domestic use (drinking, sanitation) and Industrial use.
- Trends: Industrial and domestic sector usage is increasing significantly faster than agricultural use, though agriculture remains the primary consumer.
4. Demand for Irrigation
- Need for Irrigation:
- Spatial Variability: Rainfall distribution is uneven across India.
- Temporal Variability: Rainfall is concentrated in the monsoon season (4 months).
- Water Demands of Crops: Certain crops (rice, sugarcane) are water-intensive.
- High Yielding Varieties (HYV): HYV seeds require regular, timely, and often higher amounts of water supply to achieve maximum productivity.
- Multiple cropping requires year-round water supply.
- Irrigation Methods:
- Wells and Tubewells: Account for the largest share of net irrigated area (over 60%). Critical for Green Revolution success but led to groundwater depletion in many areas (Punjab, Haryana, Western UP, Tamil Nadu).
- Canals: Second largest source, prominent in northern plains (Indira Gandhi Canal), coastal areas.
- Tanks: Important in peninsular India (Andhra Pradesh, Tamil Nadu), rely on rainfall.
5. Emerging Water Problems
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Deterioration of Water Quality:
- Sources of Pollution:
- Domestic Waste: Untreated sewage from cities and towns.
- Industrial Effluents: Toxic chemicals, heavy metals released by industries.
- Agricultural Runoff: Fertilizers (nitrates) and pesticides contaminate surface and groundwater.
- Cultural Activities: Idol immersion, disposal of waste during religious events.
- Natural Sources: Geogenic pollutants like fluoride (Rajasthan, Gujarat) and arsenic (West Bengal, Bihar).
- Impact: Spread of waterborne diseases (cholera, diarrhoea, typhoid, jaundice), ecological imbalance, eutrophication, reduced usability for domestic/industrial purposes.
- Major Polluted Rivers: Ganga and Yamuna are among the most polluted rivers in the country.
- Sources of Pollution:
-
Water Scarcity and Depletion:
- Over-extraction of groundwater, especially in agricultural belts.
- Inefficient water use in agriculture and industry.
- Growing population and urbanisation increasing demand.
- Inter-state water disputes.
6. Water Conservation and Management
- Need: Essential due to degrading quality, increasing demand, and dwindling per capita availability.
- Strategies:
- Preventing Water Pollution: Enforcing laws (Water Act 1974, Environment Protection Act 1986), establishing sewage treatment plants (STPs), promoting industrial effluent treatment. Namami Gange Programme is a key initiative.
- Recycling and Reuse: Treating wastewater to acceptable standards for specific uses (e.g., industrial cooling, irrigation) can reduce demand on freshwater sources.
- Watershed Management:
- Concept: Efficient management and conservation of surface and groundwater resources within a watershed (a geographic area draining to a common point).
- Objectives: Prevent runoff, increase storage and recharge of groundwater, involve community participation for sustainable resource use.
- Methods: Check dams, percolation tanks, afforestation, contour bunding.
- Examples: Haryali (Central Govt. sponsored), Neeru-Meeru (Water and You) in Andhra Pradesh, Arvary Pani Sansad in Alwar, Rajasthan. Ralegan Siddhi (Maharashtra) is a famous success story.
- Rainwater Harvesting (RWH):
- Concept: Capturing and storing rainwater for various uses or for recharging groundwater aquifers.
- Objectives: Meet increasing water demand, reduce runoff, avoid flooding, improve water quality, supplement groundwater.
- Methods: Rooftop harvesting, check dams, percolation pits, recharge wells.
- Significance: Particularly important in arid and semi-arid regions. Tamil Nadu is the first and only state to make rooftop RWH structure compulsory for all houses. Gendathur village in Mysuru, Karnataka, is noted for widespread rooftop RWH.
7. National Water Policy (NWP)
- The National Water Policy, 2012 (emphasises key principles, the book might refer to earlier versions too, but 2012 is the latest major one) stresses:
- Water as a prime natural resource, a basic human need, and a precious national asset.
- Integrated water resources development and management.
- Priority allocation: Drinking water followed by irrigation, hydropower, navigation, industrial, and other uses.
- Emphasis on conservation, efficiency, and demand management.
- Water pricing reflecting its value.
- Stakeholder participation.
- Consideration of inter-basin transfers.
Conclusion:
Sustainable water management is critical for India's future. It requires a multi-pronged approach involving technological solutions, policy interventions, community participation, pollution control, and promoting water use efficiency across all sectors.
Multiple Choice Questions (MCQs)
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India accounts for approximately what percentage of the world's water resources?
(a) 2.45%
(b) 4%
(c) 8%
(d) 16% -
Which sector accounts for the highest percentage of total water utilisation in India?
(a) Domestic
(b) Industrial
(c) Agricultural
(d) Power Generation -
What is the estimated total replenishable groundwater resource in India?
(a) 1,869 cu km
(b) 690 cu km
(c) 432 cu km
(d) 1,122 cu km -
Which group of states has a very high level of groundwater utilisation (often exceeding 100% of recharge)?
(a) Odisha, Kerala, Chhattisgarh
(b) Gujarat, Uttar Pradesh, Bihar
(c) Punjab, Haryana, Rajasthan, Tamil Nadu
(d) West Bengal, Assam, Madhya Pradesh -
The 'Neeru-Meeru' watershed development project is associated with which state?
(a) Rajasthan
(b) Andhra Pradesh
(c) Maharashtra
(d) Gujarat -
Which state in India has made rooftop rainwater harvesting structures compulsory for all houses?
(a) Kerala
(b) Rajasthan
(c) Gujarat
(d) Tamil Nadu -
Which of the following is NOT a major source of water pollution in Indian rivers?
(a) Untreated sewage
(b) Industrial effluents
(c) Afforestation
(d) Agricultural runoff -
The 'Haryali' program sponsored by the Central Government focuses on:
(a) Urban water supply
(b) Watershed development
(c) Canal irrigation network expansion
(d) Inter-linking of rivers -
Geogenic contamination of groundwater by Arsenic is predominantly found in which parts of India?
(a) Rajasthan and Gujarat
(b) Kerala and Tamil Nadu
(c) West Bengal and Bihar
(d) Punjab and Haryana -
According to the National Water Policy, what is the highest priority for water allocation?
(a) Irrigation
(b) Industrial Use
(c) Hydropower Generation
(d) Drinking Water
Answer Key:
- (b)
- (c)
- (c)
- (c)
- (b)
- (d)
- (c)
- (b)
- (c)
- (d)
Make sure you revise these notes thoroughly, focusing on the data, specific scheme names, and the underlying concepts of water scarcity and management. Good luck with your preparation!