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Water Resources NCERT Chapter Notes CBSE Class 12 Geography Humanitas

CBSE Class 12 Geography NCERT Chapter Notes for Water Resources Humanitas
17 April 2025 by
Akash Kumar

Water Resources NCERT Chapter Notes CBSE Class 12 Geography Humanitas

CBSE Class 12 Geography NCERT Chapter Notes for Water Resources


Water resources are essential for life, supporting agriculture, industry, and ecosystems. They include surface water, groundwater, and rainwater. Sustainable management is crucial to prevent depletion, pollution, and climate change impacts. Efficient usage and conservation ensure water security for future generations, promoting environmental balance and economic development.

Water Resources 

  • Water is a cyclic resource with abundant supplies on the globe. 
  • Approximately, 71% of Earth’s surface is covered with it but fresh water constitutes only about 3% of total water. 
  • In fact, a very small proportion of fresh water effectively available for human use. 
  • Water scarcity is the situation when the demand for water exceeds the supply and the people don’t have access to clean water.

Indian water resources

  • India counts for about 2.45% of the world’s surface area, 4% of world’s water resources and about 16% of world population. 
  • The total water available from precipitation in the country in a year is about 4000 cubic km. The availability from surface water and replenishable groundwater is 1869 cubic km.
  • Out of this, only 60% can be put to beneficial uses .Thus, the total utilisable source in the country is only 1122 cubic kilometres.

Surface water resources 

  • There are four major forces of surface water. These are river Lake Pond and tanks. 
  • In the country, they are about 10,360 rivers. And their tributaries longer than 1.6 km each. 
  • However, due to topographical, hydrological and other constraints. Only about 690 cubic km, 32% of the available surface water can be utilised.

Ground water resources 

  • The total replenishable groundwater resources in the country are about 432 cubic km. 
  • The level of groundwater utilisation is relatively high in the river basins lying in northwestern regions and parts of South India. 
  • The groundwater utilisation is very high in the states of Punjab, Haryana, Rajasthan and Tamil Nadu. 
  • However, the end of states like Chhattisgarh, Odisha, Kerala, etc, which utilise only a small proportion of their groundwater potential. 
  • States like Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra, utilising their groundwater resources at a moderate rate.

Lagoons and backwaters

  • India has a vast coastline, and the coast is very indented in some states. Due to this, a number of lagoons and lakes have formed. The states like Kerala, Odisha and West Bengal have vast surface water resources in these lagoons and lakes. 

Water demand and utilisation 

  • India has traditionally been an agrarian economy, and about two thirds of its population have been dependent on agriculture. Hence, development of irrigation to increase agricultural production has been assigned a very high priority in the Five-year plans, and multipurpose river valley projects like the Bhakra Nangal, Damodar Valley, Nagarjuna Sagar project, Etc., have been taken up. 
  • Agriculture counts for most of the surface and groundwater utilization. It accounts for 89% of the surface water at 92% of ground water utilization. 
  • While the share of industrial sector is limited to 2 % of the surface water and 5% ground water, the share of domestic sector is higher in surface water utilisation as compared to ground water.

Demand of water for irrigation 

  • In agriculture, water is mainly used for irrigation. 
  • Irrigation is needed because of spatio-temporal variability in rainfall in the country. 
  • The large tracts of the country are deficient in rainfall and are drought prone. North Western India and deccan plateau constitute such areas.
  • Even in the areas of ample rainfall like West Bengal and Bihar, in monsoon or its failure creates dry spells detrimental for agriculture. 
  • Provision of irrigation makes multiple cropping possible. It has also been found that irrigated lands have higher agricultural productivity than unirrigated land. 
  • Further, the high yielding varieties of crops need regular moisture supply, which is made possible only by developed irrigation system. 
  • In Punjab, Haryana and western Uttar Pradesh more than 85% of their net sown area is under irrigation. 
  • Of the total net irrigated area, 76.1% in Punjab and 51.3% in Haryana are irrigated through wells and tube wells. This shows that these states utilize a large proportion of their groundwater potential which has resulted in groundwater depletion in these states. 
  • Over withdrawals in some states like Rajasthan and Maharashtra, has increased fluoride concentration in groundwater. And this practice has led to increase in concentration of arsenic in parts of West Bengal and Bihar.

Emerging water problems

  • The per capita availability of water is dwindling day by day due to increase in population. The available water resources are also getting polluted with industrial, agricultural and domestic effluents, and this in turn is further limiting the availability of usable water resources.

Deterioration of water quality

  • Water quality refers to purity of water, or water without any unwanted foreign substance. 
  • The toxic substances enter lakes, streams, river, oceans and other water bodies. They get dissolved or life suspended in water. This results in the pollution of water whereby the quality of water deteriorates affecting aquatic systems. 
  • The Ganga and Yamuna are the two highly polluted rivers in the country.

Water conservation and management 

  • Since there is a declining availability of freshwater and increasing demand, the need has arisen to conserve and effectively manage this precious life giving resource for sustainable development.
  • Given that the water availability from sea ocean due to the high cost of desalinization, is considered negligible, India has to take quick steps and make effective policies and laws and adopt effective measures for its conservation. 
  • Besides developing water saving technologies and methods, attempts are also be made to prevent the pollution. 
  • There’s a need to encourage watershed development, rainwater harvesting, water recycling and reuse, and conjunctive use of water for sustaining water supply in long run.

Prevention of water pollution 

  • Available water resources are degrading rapidly. 
  • The drains carrying Agricultural (fertilizers and insecticides), domestic (solid and liquid waste) and industrial effluents join the rivers. 
  • The concentration of pollutants in rivers specially remains high during the summer season, while the flow of water is low. 
  • The central pollution control board [CPCB] in collaboration with state pollution control boards has been monitoring water quality of national aquatic resources at 507 stations. 
  • The Yamuna River is the most polluted river in the country between Delhi and Etawah. 
  • The data obtained from these stations showed that organic and bacterial contamination continues to be the main source of pollution in river. 
  • The Legislative Provision, such as the water [prevention and control of pollution] Act 1974 and environmental Protection Act 1986 have not been implemented effectively. 
  • The result is that in 1997, 251 polluting Industries were located along the rivers and Lake. 
  • The water says act. 1977 meant to reduce pollution has also made marginal impacts. 
  • There is also a strong need to generate public awareness about the importance of water and the impacts of water pollution.
  • The public awareness and action can be very effective in reducing the pollutants from agricultural activities, domestic and industrial stages.

Recycle and reuse of water 

  • Another way through which we can improve freshwater availability is by recycle and reuse. 
  • Use of water of lesser quality, such as reclaimed wastewater, would be an attractive option for industries for cooling and firefighting to reduce their water cost. 
  • Similarly, in urban areas, water after bathing and washing utensils can be used for gardening, water used for washing vehicle can also be used for gardening. 
  • Currently, recycling of water is practised on a limited scale. However, there is enormous scope for replenishing water through recycling.

Watershed management

  • Watershed management basically refers to efficient management and conservation of surface and groundwater resources. 
  • It involves prevention of runoff and storage and recharge of groundwater through various methods like percolation tanks and recharge wells, etc.
  • However, in broad sense, watershed management includes conservation, regeneration and judicious use of all resources- natural [like land, water, plants and animals] and human with in a watershed. 
  • Watershed management aims at bringing about balance between natural resources. On the one hand, and society on the other. 
  • The success of watershed development largely depends upon community participation. 
  • The central and state governments have initiated many workshop development and management programs in the country. 
  • Haryali is a Watershed Development Project sponsored by the Central Govt, which aims at enabling the ruler population to conserve water for drinking, irrigation, fisheries and afforestation. 
  • Neeru Meeru (Water and you) program in Andhra Pradesh and are arvary pani sansad Alwar Rajasthan have taken up construction of various water harvesting structures such as percolation tanks, dugout ponds [johad], checked dams, etc. Through people’s participation.
  • Tamil Nadu has made water harvesting structures in the houses compulsory. 

Rainwater harvesting 

  • Rainwater harvesting is a method to capture and store rainwater for various uses. 
  • It is also used to recharge groundwater aquifers. 
  • It is a low cost and eco friendly technique for preserving every drop of water by guiding the rainwater to borewells, pits and wells. 
  • In Rajasthan, rainwater harvesting structures locally known as Kund Or tanka [a covered underground tank] are constructed near or in the house or village to store harvested rainwater. 
  • Urban areas can specially benefit from rainwater harvesting as water demand has already outstripped supply in most of cities and towns. 
  • Apart from the above mentioned factors, the issue desalinisation of water particularly in coastal areas and brackish water in arid and semi -arid areas, transfer of water from water surplus areas to the water deficit areas through interlinking of rivers can be important remedies for solving water problem in India.
  • However, the most important issue from the point of view of individual users, household and communities is pricing of water.

The key features of National Water Policy, 2002 include

  • Irrigation and multipurpose projects to include the drinking water component, wherever there is no alternative source of drinking water.
  • Providing drinking water to all human beings and animals should be the first priority.
  • Measures should be taken to limit and regulate the exploitation of groundwater.
  • Both surface and groundwater should be regularly monitored for quality. A phased programme should be undertaken for improving water quality.
  • Conservation consciousness should be promoted through education, regulation, incentives and disincentives.
  • The efficiency of utilisation in all the diverse uses of water should be improved.
  • Awareness of water as a scarce resource should be fostered.


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