Chapter – 4

Water Resources

In this post we have given the detailed notes of class 12 Geography Book 2 Chapter 4 (Water Resources) in English. These notes are useful for the students who are going to appear in class 12 board exams.

Chapter 4: Water Resources

Introduction

• Water scarcity is a major challenge due to increasing demand and decreasing supply.  
• It is a contested issue among communities, regions, and states.  
• This chapter discusses water resources in India, their distribution, use, and conservation.  

Water Resources of India

• India has 2.45% of the world’s surface area, 4% of its water resources, and over 17% of its population.  
• Total water from precipitation is about 4,000 cubic km per year.  
• Available surface and replenishable groundwater is 1,869 cubic km, but only 60% is usable.  
• Total usable water resource is 1,122 cubic km.  

Surface Water Resources

• Major sources: rivers, lakes, ponds, and tanks.  
• India has about 10,360 rivers and tributaries longer than 1.6 km each.  
• Mean annual flow in all river basins is 1,869 cubic km, but only 690 cubic km (32%) is usable.  
• River flow depends on the size of the catchment area and rainfall.  
• The Ganga, Brahmaputra, and Barak rivers have 60% of the total surface water resources.  
• Harnessing water in south Indian rivers is mostly complete, but not in the Brahmaputra and Ganga basins.  

Groundwater Resources

• Total replenishable groundwater resources are about 432 cubic km.  
• High utilization in the northwest and parts of south India, especially in Punjab, Haryana, Rajasthan, and Tamil Nadu.  
• Low utilization in Chhattisgarh, Odisha, and Kerala.  
• Moderate utilization in Gujarat, Uttar Pradesh, Bihar, Tripura, and Maharashtra.  
• Over-utilization can lead to social and developmental problems.  

Lagoons and Backwaters

• India’s vast and indented coastline has formed many lagoons and lakes, especially in Kerala, Odisha, and West Bengal.  
• Water is generally brackish but used for fishing and irrigation.  

Water Demand and Utilization

• Agriculture is the dominant sector, accounting for 89% of surface water and 92% of groundwater use.  
• Industry uses 2% of surface water and 5% of groundwater.  
• Domestic use accounts for 9% of surface water and a smaller share of groundwater.  
• The share of agriculture is expected to decline as industry and domestic use increase.  

Demand for Irrigation

• Irrigation is necessary due to spatio-temporal variability in rainfall, with some areas being drought-prone.  
• Dry seasons and the high water requirements of certain crops also necessitate irrigation.  
• Irrigation enables multiple cropping and higher productivity.  
• High-yielding varieties need regular moisture, making irrigation crucial for the Green Revolution’s success.  
• Over-reliance on groundwater has led to depletion and quality issues in some states.  

Pradhan Mantri Krishi Sinchayee Yojana (PMKSY)

• Launched in 2015-16 to ensure access to protective irrigation for all farms.  
• Objectives include:
  • Enhancing water access and expanding the cultivable area under irrigation.  
  • Promoting integrated water management and efficient use.  
  • Improving on-farm water use efficiency.  
  • Introducing sustainable water conservation practices.  
  • Ensuring integrated development of rainfed areas.  

Emerging Water Problems

• Per capita water availability is declining due to population growth and pollution.  

Deterioration of Water Quality

• Water pollution is caused by foreign substances like microorganisms, chemicals, and waste.
• Pollutants deteriorate water quality and harm aquatic systems.  
• Organic and bacterial contamination are the main sources of river pollution.  
• The Yamuna is the most polluted river, followed by the Sabarmati, Gomti, and others.  
• Groundwater pollution is caused by heavy metals, fluoride, and nitrates.  
• Legislative measures have not been effectively implemented.  

Water Conservation and Management

• Sustainable development requires water conservation and management.  
• This includes water-saving technologies, pollution prevention, watershed development, rainwater harvesting, and recycling.  

Prevention of Water Pollution

• Major rivers have better water quality in the upper stretches.  
• In plains, rivers are polluted by agricultural, domestic, and industrial effluents.  
• Public awareness is crucial for reducing pollution.  

Recycle and Reuse of Water

• Recycling and reusing water can improve availability.  
• Industries can use reclaimed wastewater for cooling and firefighting.  
• Domestic wastewater can be used for gardening.  
• Recycling is currently limited but has enormous potential.  

Watershed Management

• Watershed management involves the efficient conservation of surface and groundwater resources.  
• It includes preventing runoff and recharging groundwater.  
• In a broader sense, it encompasses the conservation and judicious use of all resources within a watershed.  
• Community participation is crucial for successful watershed development.  
• The government and NGOs are implementing various watershed development programs.  
• Examples include Haryali, Neeru-Meeru, Arvary Pani Sansad, and mandatory water harvesting structures in Tamil Nadu.  

Rainwater Harvesting

• Rainwater harvesting captures and stores rainwater for various uses, including groundwater recharge.  
• It is a low-cost and eco-friendly technique.  
• Benefits include increased water availability, improved groundwater quality, and reduced soil erosion and flooding.  
• Traditional methods include using surface storage bodies and underground tanks.  
• Rainwater can be harvested from rooftops and open spaces.  
• It reduces dependence on groundwater and saves energy for pumping.  
• Rainwater harvesting is being adopted on a large scale, especially in urban areas.  

Other Important Topics

• Desalination of water, especially in coastal areas.  
• Transfer of water from surplus to deficit areas through inter-linking of rivers.  
• Pricing of water.  
• National Water Policy 2012.  
• Jal Kranti Abhiyan (2015-16).  

National Water Policy 2012

• The objective is to assess the current situation and propose a framework for action.  
• Recommendations cover conservation, development, and management of water resources.  
• Salient features include:
  • National water framework law and legislation for inter-State rivers.  
  • Water as an economic good after meeting basic needs.  
  • Adaptation strategies for climate change.  
  • Benchmarks for water use and water auditing.  
  • Equity in water supply between urban and rural areas.  
  • Community participation in water management.  

Jal Kranti Abhiyan (2015-16)

• Launched to ensure water security through per capita availability.  
• Aims to involve local bodies, NGOs, and citizens in awareness creation.  
• Activities include:
  • Creating ‘Jal Grams’ in water-stressed villages.  
  • Identifying model command areas.  
  • Abating pollution and constructing arsenic-free wells.  
  • Mass awareness campaigns.  
• Designed to provide livelihood and food security through water security.

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