What topics are covered in the Water Resources notes for Class 12 - Humanities India - People And Economy?

The notes for Water Resources cover every section of the official NCERT chapter — definitions, key concepts, formulas, derivations, and worked examples — written for Class 12 - Humanities India - People And Economy students.

Are these notes for Water Resources free?

Yes. Every notes page on Kedovo is free, with no PDF download required. Open the page on any device — phone, tablet, or laptop.

Are the notes aligned with the CBSE Class 12 - Humanities syllabus?

Yes. Notes are generated directly from the NCERT Class 12 - Humanities India - People And Economy textbook chapter for Water Resources and quality-checked for syllabus alignment before being published.

Can I use these notes for last-minute revision?

Yes, though they are written for understanding rather than speed — these notes are free and cover every section of Water Resources. For a condensed night-before version, the Important Points page is a focused bullet list, and comes with Kedovo's Topper plan.

Are the notes for Water Resources prepared by experts?

Notes are AI-generated using Gemini and reviewed through a multi-step quality check that verifies factual correctness, syllabus alignment, and age-appropriate language for Class 12 - Humanities students before publishing.

Water Resources Class 12 India - People And Economy Notes

WATER RESOURCES

Water is a vital resource, and its scarcity is predicted to be one of the greatest challenges of the future. This is because the demand for water is increasing due to population growth and development, while supplies are shrinking due to overuse and pollution.

Although about 71% of the Earth's surface is covered by water, only about 3% of it is freshwater. Of this small amount, an even smaller portion is actually available for human use. This limited supply of freshwater is not evenly distributed across the globe, leading to tensions and disputes over its control and use among communities, regions, and even states. Therefore, it's crucial to assess, efficiently use, and conserve our water resources for sustainable development.

Note

Water is a cyclic resource, meaning it is constantly renewed through the water cycle. However, the amount of usable freshwater at any given time is limited.

Water Resources of India

India faces a significant challenge in managing its water resources. Here's a quick look at the numbers:

India has about 2.45% of the world's surface area.
It holds 4% of the world's water resources.
It supports over 17% of the world's population.

The total amount of water available from rainfall (precipitation) in a year is about 4,000 cubic km. The water available from surface sources (like rivers) and replenishable groundwater is 1,869 cubic km. However, we can only put about 60% of this to beneficial use.

This means the total utilisable water resource in India is only 1,122 cubic km.

Surface Water Resources

There are four main sources of surface water in India:

Rivers
Lakes
Ponds
Tanks

India has approximately 10,360 rivers and their tributaries (longer than 1.6 km). The total average annual flow in all river basins is estimated to be 1,869 cubic km. However, due to geographical and hydrological constraints, only about 690 cubic km (or 32%) of this surface water can actually be utilised.

The amount of water in a river depends on the size of its catchment area (the area of land from which it collects water) and the amount of rainfall in that area. In India, rainfall is highly variable and concentrated mainly during the monsoon season.

Rivers like the Ganga, the Brahmaputra, and the Indus have enormous catchment areas. These river basins, along with the Barak river basin, receive high precipitation.

They account for only about one-third of the total area of the country.
But, they hold 60% of the total surface water resources.

Example

Think of a river basin as a giant funnel. The bigger the funnel (catchment area) and the more it rains into it, the more water flows out through the spout (the river). The Ganga and Brahmaputra basins are like massive funnels in a very rainy part of the country.

While much of the water in South Indian rivers like the Godavari, the Krishna, and the Kaveri has been harnessed for use, the potential of the Ganga and Brahmaputra basins is yet to be fully utilised.

Groundwater Resources

The total replenishable groundwater in India is about 432 cubic km. The use of this groundwater is very high in the river basins of the north-western region and parts of southern India.

Very High Utilisation: States like Punjab, Haryana, Rajasthan, and Tamil Nadu use a very large portion of their groundwater.
Moderate Utilisation: States like Gujarat, Uttar Pradesh, Bihar, Tripura, and Maharashtra use their groundwater at a moderate rate.
Low Utilisation: States like Chhattisgarh, Odisha, and Kerala use only a small proportion of their groundwater potential.

If the current trend of high utilisation continues, the demand for water will soon exceed the supply, which could harm development and cause social unrest.

Lagoons and Backwaters

India has a long and indented (uneven) coastline. This has led to the formation of many lagoons and lakes.

States like Kerala, Odisha, and West Bengal have vast surface water resources in these lagoons.
The water in these bodies is generally brackish (salty), but it is used for fishing and irrigating certain crops like paddy and coconut.

Water Demand and Utilisation

India has traditionally been an agrarian economy, with most of its population dependent on agriculture. Because of this, developing irrigation to boost food production has always been a top priority in the Five Year Plans. This led to the construction of major multipurpose river valley projects like the Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, and the Indira Gandhi Canal Project.

Today, India's water demand is dominated by the needs of irrigation.

Sectoral Utilisation of Water:

Agriculture: This sector is the biggest user, accounting for 89% of surface water and 92% of groundwater utilisation.
Industrial Sector: Uses a smaller share, at 2% of surface water and 5% of groundwater.
Domestic Sector: Uses 9% of surface water, a higher share than its groundwater use.

Note

As India continues to develop, the share of water used by the industrial and domestic sectors is expected to increase in the future.

Demand of Water for Irrigation

Water in agriculture is mainly used for irrigation. Irrigation is essential in India for several reasons:

Uneven Rainfall: Rainfall varies greatly across time and space. Large parts of the country, like north-western India and the Deccan plateau, are drought-prone.
Dry Seasons: Most parts of the country have dry winter and summer seasons, making agriculture difficult without irrigation.
Monsoon Breaks: Even in areas with high rainfall, like West Bengal and Bihar, a failure or break in the monsoon can create dry spells that damage crops.
Water-Intensive Crops: Crops like rice, sugarcane, and jute require a large amount of water that can only be supplied through irrigation.

Benefits of Irrigation:

It makes multiple cropping (growing more than one crop on the same land in a year) possible.
Irrigated lands have higher agricultural productivity than unirrigated lands.
High Yielding Varieties (HYV) of crops, central to the Green Revolution, need a regular supply of moisture, which only developed irrigation systems can provide.

The success of the Green Revolution in Punjab, Haryana, and western Uttar Pradesh is largely due to developed irrigation systems. In these states, over 85% of the net sown area is under irrigation, mostly for wheat and rice. A large portion of this irrigation (76.1% in Punjab and 51.3% in Haryana) comes from wells and tubewells, meaning they heavily rely on groundwater.

Negative Impacts of Over-irrigation:

Groundwater Depletion: The overuse of groundwater has led to a significant decline in the water table in these states.
Increased Contaminants: Over-withdrawal of groundwater has led to increased fluoride concentration in states like Rajasthan and Maharashtra, and arsenic concentration in parts of West Bengal and Bihar.
Soil Salinity: Intensive irrigation is increasing the salt content in the soil, making it less fertile.

Pradhan Mantri Krishi Sinchayee Yojana (PMKSY)

Launched by the Central Government in 2015-16, the PMKSY aims to ensure that every agricultural farm in the country has access to some form of protective irrigation. Its key objectives include:

Expanding the cultivable area under assured irrigation (Har khet ko pani).
Improving water use efficiency through technologies like drip and sprinkler irrigation (Per drop more crop).
Promoting sustainable water conservation practices.
Integrating the development of rain-fed areas through soil and water conservation.

Emerging Water Problems

Two major water problems are emerging in India:

Declining Availability: The per capita (per person) availability of water is decreasing daily due to the increasing population.
Pollution: Available water resources are being polluted by industrial, agricultural, and domestic waste, which further limits the supply of usable water.

Deterioration of Water Quality

Water quality refers to the purity of water, meaning it is free from unwanted foreign substances. Water gets polluted by things like:

Micro-organisms
Chemicals
Industrial and other wastes

When these toxic substances enter water bodies like rivers and lakes, they either dissolve or remain suspended in the water. This pollutes the water, making it unfit for human use and harming aquatic ecosystems. Sometimes, these pollutants also seep down and contaminate groundwater.

Water Conservation and Management

With freshwater availability declining and demand rising, it is essential to conserve and manage this precious resource for sustainable development. Key strategies for water conservation and management include:

Preventing water pollution.
Developing water-saving technologies.
Encouraging watershed development.
Promoting rainwater harvesting.
Recycling and reusing water.
Using surface water and groundwater in a combined, efficient manner (conjunctive use).

Prevention of Water Pollution

India's rivers are rapidly degrading. While the water quality is generally better in the less populated hilly areas, it deteriorates in the plains where river water is used intensively for irrigation, drinking, and industrial purposes.

The main sources of river pollution are:

Agricultural Runoff: Fertilizers and insecticides washed from fields.
Domestic Waste: Solid and liquid waste from cities and towns.
Industrial Effluents: Untreated waste from factories.

Pollution levels in rivers are highest during the summer when the water flow is low. According to the Central Pollution Control Board (CPCB), the main sources of pollution in rivers are organic and bacterial contamination.

The Yamuna river is the most polluted in the country, especially between Delhi and Etawah.
Other severely polluted rivers include the Sabarmati, Gomti, Ganga (at Kanpur and Varanasi), and Musi.
Groundwater is also getting polluted by high concentrations of heavy metals, fluoride, and nitrates in different parts of the country.

Laws like the Water (Prevention and Control of Pollution) Act, 1974, and the Environment Protection Act, 1986, have not been implemented effectively. Public awareness is crucial to reduce pollution from all sources.

Recycle and Reuse of Water

Recycling and reusing water can significantly improve the availability of freshwater. [!example]

Industries can use lower-quality reclaimed wastewater for cooling and firefighting, which saves fresh water and reduces costs.
In cities, water used for bathing and washing utensils can be reused for gardening.
This conserves high-quality water for drinking purposes.

Currently, water recycling is practiced on a limited scale, but there is enormous potential to expand it.

Watershed Management

Watershed management refers to the efficient management and conservation of surface and groundwater resources. It involves methods like preventing runoff and recharging groundwater through percolation tanks and recharge wells.

In a broader sense, watershed management includes the conservation and judicious use of all resources—land, water, plants, and animals—within a watershed area. The goal is to create a balance between natural resources and society. The success of these projects largely depends on community participation.

Several government and non-governmental programs are underway:

Haryali: A Central Government-sponsored project implemented by Gram Panchayats with people's participation. It aims to conserve water for drinking, irrigation, fisheries, and afforestation.
Atal Bhujal Yojana (Atal Jal): Implemented in water-stressed districts of seven states, it focuses on changing community behaviour from consumption to conservation and smart water management.
Neeru-Meeru (Water and You): A program in Andhra Pradesh involving people in building water-harvesting structures.
Arvary Pani Sansad: A program in Alwar, Rajasthan, that has also constructed water-harvesting structures through people's participation.
Tamil Nadu: This state has made it compulsory for all houses to have water-harvesting structures.

Watershed Development in Ralegan Siddhi, Ahmadnagar, Maharashtra: A Case Study

Ralegan Siddhi is a small village in Maharashtra that has become a model for watershed development.

The Problem: In 1975, the village was trapped in poverty and illegal liquor trade.
The Transformation: A retired army personnel settled in the village and motivated the villagers to participate in watershed development. He encouraged family planning, voluntary labour, a ban on open grazing and tree felling, and liquor prohibition.
Community Action: Villagers voluntarily repaired a leaking percolation tank, which led to the wells filling with water in the summer for the first time. This built trust and momentum.
Social Reforms: A youth group was formed to ban the dowry system and caste discrimination. The cultivation of water-intensive crops like sugarcane was banned in favour of crops with low water requirements.
The Result: Today, the village has adequate water, and agriculture is flourishing. The community manages its own affairs through consensus and informal courts, showing remarkable self-reliance.

Rainwater Harvesting

Rainwater harvesting is a technique to capture and store rainwater for various uses or to recharge groundwater aquifers. It is a low-cost, eco-friendly method.

Benefits of Rainwater Harvesting:

Increases water availability.
Checks the declining groundwater table.
Improves groundwater quality by diluting contaminants like fluoride and nitrates.
Prevents soil erosion and flooding.
Arrests saltwater intrusion in coastal areas.

Traditional methods in rural areas include using surface storage bodies like lakes and ponds. In Rajasthan, structures called Kund or Tanka (covered underground tanks) are built to store rainwater. Modern methods include harvesting rainwater from rooftops and open spaces, which is especially beneficial for urban areas where water demand often exceeds supply.

Highlights of India's National Water Policy 2012

The National Water Policy, 2012 was created to provide a framework for the conservation, development, and management of water resources. Key features include:

Emphasis on a national water framework law for managing inter-state rivers.
Treating water as an economic good to promote conservation, after meeting essential needs like drinking water and sanitation.
Developing adaptation strategies for climate change.
Creating benchmarks for water use (water footprints) to ensure efficiency.
Removing the large disparity in water supply between urban and rural areas.
Managing water projects with community participation.

Jal Kranti Abhiyan (2015-16)

The Jal Kranti Abhiyan was launched by the Government of India to ensure water security in the country. It aims to involve local bodies, NGOs, and citizens in water conservation.

Key activities proposed under this campaign include:

Selecting one water-stressed village in each district to create a 'Jal Gram'.
Identifying model command areas for efficient irrigation.
Reducing pollution through water conservation, artificial recharge, and construction of Arsenic-free wells.
Creating mass awareness through media and school competitions.

The ultimate goal of the campaign is to provide livelihood and food security through water security.

Water ResourcesClass 12 India - People And Economy Notes