Water Resources Class 12 Geography Chapter 4 CBSE Notes 2025-26

Water is one of the most essential and scarce resources in India today. While the Earth’s surface is covered by nearly 71% water, only a tiny portion of this—about 3%—is freshwater. Even within this, the amount usable by humans is limited due to factors like uneven distribution, seasonal variability, and pollution. 

India has significant pressure on its water resources due to its large population and diverse climate conditions, which has made assessment, efficient use, and conservation of water crucial for sustainable development.

India receives around 4,000 cubic kilometres of water from annual precipitation, but only about 1,122 cubic km are actually usable. The usable water comes from two main sources: surface water and replenishable groundwater. Due to topographical and hydrological limitations, only a fraction of the total water can be effectively used by people.

There are four main sources of surface water: rivers, lakes, ponds, and tanks. India has over 10,000 rivers and tributaries, most over 1.6 km in length. The major rivers, including the Ganga, Brahmaputra, and Indus, account for roughly one-third of India’s area but provide 60% of all surface water. 

However, only around 690 cubic km, or 32% of the total surface water, is actually usable due to factors such as river basin size, rainfall distribution, and the capacity to harness river flows. Southern rivers like the Godavari, Krishna, and Kaveri have mostly been tapped, but there is still considerable untapped potential in the Ganga and Brahmaputra basins.

The replenishable groundwater resources in India are about 432 cubic km. High groundwater use is seen in places like Punjab, Haryana, Rajasthan, and Tamil Nadu, whereas other states like Odisha, Kerala, and Chhattisgarh use much less.

Regions with moderate usage include Gujarat, Uttar Pradesh, Bihar, Tripura, and Maharashtra. Over-dependence on groundwater, especially in north-western states, may lead to scarcity and can pose a threat to agricultural and social stability if current consumption trends continue. Groundwater is most critical in areas with irregular rainfall or dry climates.

India’s coastline supports the formation of lagoons and backwaters, especially in Kerala, Odisha, and West Bengal. Although this water tends to be brackish, it supports local fisheries and is used for irrigating crops like paddy and coconut.

Irrigation for agriculture is by far the largest consumer of water in India, accounting for 89% of surface water and 92% of groundwater usage. Water is also needed for industrial (2% surface, 5% groundwater) and domestic use (9% surface, 3% groundwater). With economic development, industrial and domestic demand is set to rise, but agriculture will continue to lead in overall consumption.

Major multipurpose river valley projects—such as Bhakra-Nangal, Hirakud, and Nagarjuna Sagar—reflect the emphasis on irrigation to boost food grain production.

Due to erratic and spatially variable rainfall, large parts of India—such as northwest India and the Deccan plateau—require reliable irrigation. Even areas with high rainfall (like West Bengal and Bihar) sometimes experience dry spells that can threaten crops. 

Crops such as rice, sugarcane, and jute need more water than what is available from rainfall alone. Areas with extensive irrigation, such as Punjab, Haryana, and western Uttar Pradesh, have seen the most benefit from programs like the Green Revolution. This has resulted in high cropping intensity but has also contributed to water table decline and contamination with elements such as fluoride and arsenic in water.

• Irrigation enables multiple cropping and higher yields.
• Overuse can cause groundwater depletion and increase soil salinity.
• Efficient policies like the Pradhan Mantri Krishi Sinchayee Yojana (PMKSY) aim to provide water to every field (Har Khet Ko Pani) and improve on-farm water management (Per Drop More Crop).

India’s per capita water availability is falling because of population growth and increasing pollution from agricultural, industrial, and domestic sources. Deterioration of water quality makes resources unfit for use. 

Rivers in heavily populated plains are especially at risk, receiving pollutants throughout their course. Seasonal variations also mean that river pollution peaks during the dry summer months. 

Some of the most polluted rivers include the Yamuna, Sabarmati, Gomti, Kali, and especially the Ganga and its tributaries in urban and industrial zones.

The need to manage and conserve water in India is urgent, given the increasing gap between supply and demand. 

Key measures include preventing water pollution through better waste management and regular monitoring, recycling and reusing water for industrial and domestic purposes (such as gardening and cooling), and promoting public awareness about reducing water pollution.

• Law enforcement is often weak; stronger implementation and public participation are necessary.
• Recycling and reuse of water can reduce demand on fresh water supplies, although it is still at a nascent stage in India.

Watershed management is the integrated conservation of land, water, and other natural resources within a drainage basin. It involves community-driven efforts to prevent runoff, recharge groundwater, and use resources judiciously. 

Government, non-governmental organisations, and local communities carry out watershed projects such as Haryali, Atal Bhujal Yojana, Neeru-Meeru (Andhra Pradesh), and the Arvary Pani Sansad (Rajasthan). 

Community participation and voluntary labour have been essential, with success stories like Ralegan Siddhi in Maharashtra highlighting the transformative effects of such projects—leading to improved water supply, green cover, and livelihoods.

This practice involves collecting and storing rainwater for use or recharging groundwater. Traditional tanks and ponds, as well as structures like kunds and tankas in Rajasthan, have been part of Indian villages for centuries. 

Urban areas are increasingly adopting rainwater harvesting as demand outpaces supply. Benefits include increased water availability, better groundwater quality, and prevention of soil erosion and flooding. Some states, like Tamil Nadu, have made rainwater harvesting structures compulsory in new buildings.

The National Water Policy 2012 and programmes like the Jal Kranti Abhiyan (2015–16) focus on laws for optimal river management, reducing urban-rural disparities, regular auditing of projects, prioritising safe drinking water, and promoting community involvement. 

The Jal Kranti Abhiyan aims to select and improve at least one water-stressed ‘Jal Gram’ in each district, emphasising awareness, conservation, and pollution abatement.

• Model command areas are identified for best practices in water management.
• School competitions and media campaigns raise awareness about water conservation.

India’s water resource management must balance growing demands from agriculture, industry, and households with protection against depletion and pollution. Adopting traditional and modern conservation methods, encouraging community participation, and strengthening legal frameworks are crucial steps toward sustainable water use for future generations.

Class 12 Geography Chapter 4 Notes – Water Resources: Key Points for Quick Revision

These CBSE Class 12 Geography notes for Chapter 4 cover the full scope of Water Resources in India—from availability and demand to conservation strategies. They help students quickly revise all essential facts, statistics, and key programmes, crucial for scoring well in board exams.

The concise pointers and summaries provide a structured approach for last-minute revision. With real examples and easy explanations on surface water, groundwater, irrigation, and conservation policies, these notes make complex topics simple and exam-ready for every student.