CBSE Class 10 Social Science Water Resources Notes Set 03

These CBSE Class 10 Geography notes for Chapter 3 Water Resources cover the hydrological cycle and global water facts, water scarcity and its causes, the need for water conservation, multipurpose projects and their advantages/disadvantages, the Narmada Bachao Andolan, and traditional and modern rainwater harvesting techniques, with a glossary at the end.

Introduction

Three-fourths of the earth's surface is covered with water, but only a small proportion of this is usable freshwater. Water is a renewable resource, continuously circulated through the hydrological cycle. Its uses are immense: domestic purposes (cooking, drinking, washing), agriculture, pastoral and manufacturing industries, and generating hydro-electric power. Freshwater is mainly obtained from surface run-off and groundwater. The water cycle has four main stages: evaporation, transpiration, condensation and precipitation.

Facts and Figures about Water

(According to the UN World Water Development Report, 2003)

About 97% of the world's total water volume exists as oceans, with only about 2.5% as freshwater; nearly 70% of this freshwater is locked in ice sheets and glaciers (Antarctica, Greenland and mountain regions), with a little under 30% stored as groundwater in the world's aquifers. India receives about 4% of global precipitation, yet ranks 133rd in the world for water availability per person per year. India's total renewable water resources are estimated at about 1,897 cubic km per year. By 2025, large parts of India are predicted to face absolute water scarcity. Hydroelectric power contributes about 22% of India's total electricity production. Jawaharlal Nehru famously called multipurpose projects "the temples of modern India", seeing them as vehicles of national development and progress.

Water Scarcity

Water availability varies across both space and time. Scarcity is caused by over-exploitation, excessive use, and unequal access to water among different social groups; water resources are often over-exploited to expand irrigated, dry-season agriculture. In some areas, water quantity is sufficient but poor water quality still causes scarcity. Key drivers of water scarcity include: growing population; industrialisation and urbanisation; commercialisation of agriculture; and variation in seasonal and annual precipitation.

Need for Water Conservation and Management

Conserving and managing water resources is essential: to protect against health hazards; to prevent degradation of natural ecosystems; to support multipurpose river and integrated water projects; and to ensure food security and sustain livelihoods and productive activity.

Water Resource Management

A multipurpose project is one that serves several purposes at once — for example, irrigation and electricity generation together. The Swedish expert Falkenmark defined "water stress" as occurring when water availability falls between 1,000 and 1,600 cubic metres per person per year.

Advantages of Multipurpose Projects

Power generation: they produce clean, pollution-free and comparatively cheap energy, vital for industry and agriculture; per the Economic Survey 2022-23, such projects produce more than 42,104.6 MW of power.
Flood control: by storing water, these projects control floods, turning several "rivers of sorrow" into rivers of benefit — for example, the Kosi river.
Soil conservation: slowing down water flow helps conserve soil.
Irrigation: canals dug from these projects irrigate dry areas during the dry season.
Afforestation: trees are systematically planted in and around reservoirs, helping preserve wildlife and the natural ecosystem.
Water navigation: these projects support inland water navigation along rivers or canals, the cheapest means of transporting heavy goods.
Fisheries: reservoirs provide ideal breeding conditions for selected fish varieties.
Tourism: well-maintained, scientifically developed projects often become tourist attractions.

Disadvantages of Multipurpose Projects

High cost: building dams requires very high capital investment, engineering skill and modern machinery, which are not always easily available.
Adverse environmental impact: a wide variety of flora, fauna and human settlements can be submerged by the reservoir formed behind a dam.
Reduced soil fertility: without annual floods, downstream soil no longer receives nutrient-rich silt, reducing fertility.
Adverse impact on aquatic life: fish downstream no longer receive sufficient nutrients once a dam is built.
Seasonal water flow: many Indian rivers flow for only part of the year, so water may be insufficient to justify a dam.
Inter-state disputes: states often dispute water sharing, dam height and related issues.
Displacement of local communities: local people frequently lose their land and livelihood, and their limited access to resources, for the stated benefit of the wider nation.
Changed cropping patterns: assured irrigation has pushed many farmers toward water-intensive, commercial crops, which has, in turn, led to soil salinisation and ecological imbalance.

In the 11th century, Bhopal Lake, one of the largest artificial lakes of its time, was built.

The Narmada Bachao Andolan

The Narmada Bachao Andolan (Save Narmada Movement) is an NGO that mobilised tribal people, farmers, environmentalists and human rights activists against the Sardar Sarovar Dam on the Narmada river in Gujarat. It originally focused on environmental concerns over trees submerged by the dam's reservoir; more recently, it has focused on securing full rehabilitation for displaced, poor communities.

Rainwater Harvesting

Rainwater harvesting is a technique for increasing groundwater recharge by capturing and storing rainwater, using structures such as percolation pits and check dams. Rooftop rainwater harvesting is especially common practice in Shillong, Meghalaya.

Traditional Water Conservation Techniques

People in mountainous regions built diversion channels, known as 'guls' and 'kuls', for agriculture. Rooftop rainwater harvesting was traditionally used to store drinking water, especially in Rajasthan. In the flood plains of Bengal, people developed inundation channels to irrigate fields. In arid and semi-arid regions, agricultural fields were sometimes converted into rain-fed storage structures that allowed water to stand and moisten the soil, such as the 'Khadins' of Jaisalmer and 'Johads' found elsewhere in Rajasthan. In Meghalaya, a system of tapping stream and spring water using bamboo pipes, around 200 years old, remains in use.

Rainwater Harvesting Through Tanks

In the semi-arid and arid regions of Rajasthan, particularly Phalodi, Bikaner and Barmer, many houses have underground tanks for storing water, as part of a well-developed rooftop rainwater harvesting system. Rain falling on rooftops travelled down pipes into these tanks; the first rain of a spell was usually not collected, since it would be used to clean the roof and pipes first, with water from subsequent showers then collected for storage. Tamil Nadu was the first Indian state to make rooftop rainwater harvesting structures compulsory for all houses statewide, with legal provisions to penalise those who do not comply.

Glossary

Dam: an embankment or structure built across a river to store water for various uses.
Drip Irrigation: an irrigation method where water is delivered in drops near a plant's roots, mainly to conserve moisture.
Hydrological Cycle: the continuous circulation of water between the hydrosphere, atmosphere and lithosphere, in which water changes its physical state.
Inundation Canal: a canal built to divert floodwater, mainly during the rainy season.
Irrigation: artificial means of supplying water to farmland, through canals, wells, tube wells or tanks.
Multipurpose Projects: river valley projects developed after Independence for the integrated development of water resources.
Perennial Canal: a canal diverted from a river that flows year-round.
Rainwater Harvesting: a technique for storing rainwater, river water or groundwater to meet population needs.
River Water Disputes: disputes over sharing the water of rivers that flow through several states.
Surface Water: water flowing on the earth's surface, such as rivers, streams and lakes.
Tank: a natural or man-made reservoir for storing rainwater.
Water Scarcity: a shortage of water, caused by natural or human factors.