Chapter – 3

Water Resources

In this post we have given the detailed notes of class 10 Social Science (Geography) Chapter 3 Water Resources in English. These notes are useful for the students who are going to appear in class 10 board exams.

Chapter 3: Water Resources

Water — A Vital Resource

Water is a vital and renewable natural resource that is essential for life, agriculture, industry, transport, and countless human activities. About three-fourths of the earth’s surface is covered with water, but only a very small proportion of this is fresh water that can actually be used for drinking, irrigation and industry.

• 97.5% of the world’s water is saline (ocean water) and only 2.5% is fresh water.
• Nearly 70% of this fresh water occurs as ice sheets and glaciers in Antarctica, Greenland and mountainous regions.
• The rest is present as groundwater, in soil moisture, in the atmosphere, and as fresh water lakes and rivers.
• India accounts for about 4% of the world’s water resources while it supports about 16-17% of the world’s population, which makes water availability per person relatively low.

Water Scarcity and the Need for Water Conservation and Management

Water scarcity is often thought to be a problem only of low rainfall or drought-prone regions. However, water scarcity is, in most cases, related to the availability, quality and management of water rather than simply to its physical shortage.

Uneven Distribution of Water Resources

• Water resources are unevenly distributed over space in India — some regions (like the north-eastern states) are water abundant while others (like Rajasthan) are water deficient.
• Even in areas with adequate rainfall or river water, water may still be scarce due to seasonal variation, poor storage and inefficient distribution.

Deterioration of Water Quality

• Water quality has deteriorated due to the addition of unwanted, harmful substances, making it hazardous for use.
• Sources of pollution include domestic and industrial waste, chemical and fertiliser run-off from agricultural fields, and dumping of untreated sewage into rivers and lakes.
• Even water-abundant regions can face a water crisis simply because the available water is not fit for use.

Causes of Water Scarcity

Growing Population

India’s population has grown enormously, increasing the demand for water for drinking, cooking and sanitation. More people also means more water is needed to produce more food, which puts extra pressure on water resources.

Increasing Demand of Agriculture

• To meet the demand of increasing population, and to increase food-grain production, water resources are being over-utilised to expand irrigated areas and grow water-intensive crops.
• Multiple cropping and the cultivation of crops like sugarcane and paddy, which require large amounts of water, has increased the pressure on existing water resources.
• Most farmers use groundwater through tube wells and pump sets for irrigation, leading to falling groundwater levels.

Industrialisation

• Post-independence, the growing number of industries has made matters worse by exerting pressure on existing freshwater resources.
• Industries need power, and a large number of power plants are hydroelectric or thermal, which also need water in large amounts.
• Industries also draw heavily on groundwater and are among the largest consumers and polluters of water through effluent discharge.

Urbanisation

• Multiplying urban centres with large and dense populations and urban lifestyles have added to the problem of water scarcity.
• Overexploitation of water resources to meet the needs of the urban population, industry and agriculture has resulted in a fall in groundwater levels.

Over-Exploitation of Groundwater

• Housing societies and colonies in cities have their own groundwater pumping devices to meet their water needs, leading to falling groundwater levels.
• This has adversely affected water availability and, in many places, has led to a decline in groundwater quality as well.

Multi-Purpose River Projects and Integrated Water Resources Management

Meaning and Types of Dams

A dam is a barrier built across flowing water that obstructs, directs or slows down the flow, often creating a reservoir, lake or impoundment. Dams can be classified on the basis of structure, height and the material used in construction.

• On the basis of the height of dams, they can be classified as large, medium and small dams.
• Traditionally, dams were built to impound rivers and rainwater that could be used later for irrigating agricultural fields.
• Today dams are built not just for irrigation but for a variety of purposes.

Why Multi-Purpose River Valley Projects?

Multi-purpose river valley projects are so called because they are planned and constructed to serve several purposes simultaneously.

• Irrigation — supplying water for agriculture to increase food-grain production.
• Electricity generation — hydroelectric power production.
• Water supply — for domestic and industrial use.
• Flood control — regulating the flow of river water to reduce flood damage.
• Recreation — reservoirs used for tourism and recreational activities.
• Inland navigation — reservoirs are used for the development of inland navigation.
• Fish breeding — reservoirs also aid in the breeding of fish.

Hence, river valley projects are also known as “multi-purpose projects” as they are designed to serve several purposes at the same time. Jawaharlal Nehru referred to dams as the “temples of modern India”, believing that they would integrate development of agriculture and the village economy with rapid industrialisation and growth of the urban economy.

Examples of Multi-Purpose River Valley Projects

• Bhakra Nangal Project — built on the Sutlej river in Himachal Pradesh/Punjab; one of the highest dams in India, providing irrigation, electricity and drinking water to Punjab, Haryana and Rajasthan.
• Hirakud Project — built on the Mahanadi river in Odisha; one of the longest dams in the world, used for irrigation, flood control and power generation.
• Damodar Valley Project — built on the Damodar river in Jharkhand-West Bengal, modelled on the Tennessee Valley Authority (USA); provides irrigation, flood control and electricity generation.
• Nagarjuna Sagar Dam — built on the Krishna river in Andhra Pradesh/Telangana; one of the largest masonry dams in the world, used for irrigation and power generation.
• Tehri Dam — built on the Bhagirathi river in Uttarakhand; one of the tallest dams in India, used for irrigation, power generation and water supply.
• Sardar Sarovar Dam — built on the Narmada river, spanning Gujarat, Madhya Pradesh, Maharashtra and Rajasthan; used for irrigation, power generation and drinking water supply, and is also one of the most controversial dam projects in India.

Benefits and Controversies of Dams

Benefits of Multi-Purpose Projects

• They help in irrigating agricultural fields, thereby increasing food-grain production.
• Generate hydroelectricity for industries and households.
• Provide domestic and industrial water supply.
• Help in controlling floods by regulating the flow of water.
• Promote fish breeding, recreation and inland navigation.

Ecological, Social and Economic Issues with Dams

In recent decades, multi-purpose projects and large dams have come under great scrutiny and opposition for several reasons.

• Change in river flow — dams fragment rivers, changing the natural flow of water, causing poor sediment flow to areas downstream and excessive sedimentation at the reservoir, leading to rockier stream beds and poorer habitats downstream.
• Effect on aquatic life — reduced flow of water below the dam affects the natural aquatic flora and fauna and hampers the migration of aquatic species, especially for spawning.
• Submergence and deforestation — the construction of large dams results in the submergence of extensive forest and agricultural land, resulting in loss of vegetation and biodiversity.
• Displacement — dams are also built to control floods, but the construction of a large number of dams has also aggravated flood situations due to sedimentation in the reservoirs; more importantly, they often displace local communities, whose livelihoods depend on these ecosystems, without adequate compensation or rehabilitation.
• Resettlement issues — locals, especially tribal populations, who are displaced by dam construction, are seldom fully compensated or resettled properly, and lose access to their land, forests and traditional livelihoods.
• Seismic activity — the massive weight of water impounded in reservoirs has, in some cases, been linked to an increase in seismic activity (reservoir-induced seismicity) in the surrounding areas.
• Interstate water disputes — multi-purpose projects that are constructed for the purpose of integrated water resources management often lead to conflicts between states over the sharing of water.
• Economic viability — many multi-purpose projects have also been criticised because the costs frequently outweighed the benefits, given the huge investment required for construction and the loss of forests without adequate compensatory afforestation.

Narmada Bachao Andolan

The Sardar Sarovar Dam, built on the Narmada river, has been one of the most bitterly contested dam projects in the country. The Narmada Bachao Andolan is a social movement made up of tribal people, farmers, environmentalists and human rights activists who opposed the dam, protesting against the massive displacement of local communities and the large-scale submergence of forests and agricultural land, and demanding proper rehabilitation for those affected.

Sedimentation and Reduced Water-Holding Capacity

• Sediments that would otherwise flow downstream and enrich the soil of the flood plains get accumulated in the reservoir, reducing its water-holding capacity over time.
• This reduces the reservoir’s storage capacity and hence its long-term usefulness for irrigation and power generation.
• Lack of sediment flow downstream also leads to erosion of the river banks, as the river tries to compensate by cutting into its own banks and bed.

Rainwater Harvesting

Rainwater harvesting is a traditional and efficient technique of collecting and storing rainwater for future use, especially in areas with low or erratic rainfall. It also helps recharge groundwater and provides a decentralised, environmentally sound alternative to large dams.

Traditional Rainwater Harvesting Systems

• Guls and Kuls of the Western Himalayas — diversion channels built along hill slopes to carry glacial and stream water to agricultural fields; a traditional method still used in the hilly regions of Himachal Pradesh and Uttarakhand.
• Rooftop Rainwater Harvesting in Rajasthan — almost every house in the semi-arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, has traditionally had underground rooms constructed near the house or the courtyard to store rainwater collected from rooftops.
• Rooftop Rainwater Harvesting in Shillong — Meghalaya, despite being one of the wettest places on earth, faces acute shortage of drinking water; almost every household in the city of Shillong practises rooftop rainwater harvesting to meet water needs.
• Tankas in Rajasthan — underground tanks (tankas) built for storing rainwater, traditionally found in the houses of Bikaner, Phalodi and Barmer; used for drinking purposes, especially during the summer months.
• Khadin and Johad in Arid Regions — the “khadin” system (in western Rajasthan) and “johads” (in other parts of Rajasthan) are traditional rainwater harvesting techniques used to store rainwater for agricultural and drinking purposes in arid and semi-arid regions.
• Bamboo Drip Irrigation in Meghalaya — an ingenious 200-year-old system of tapping stream and spring water using bamboo pipes; water is transported over long distances through bamboo pipes and then made to drip on the roots of plants, used mainly for irrigating black pepper and betel leaf plantations.

Modern Methods of Water Conservation

• Rooftop rainwater harvesting structures are being built in urban areas to store rainwater and recharge groundwater, especially in states like Tamil Nadu where it has been made compulsory.
• Watershed development and management programmes help conserve and recharge groundwater.
• Drip and sprinkler irrigation methods help in efficient use of water for agriculture and reduce wastage.
• Recycling and reuse of wastewater after treatment for non-drinking purposes helps reduce demand on freshwater sources.
• Public awareness campaigns and community participation are being encouraged to promote responsible water use and conservation practices.

Key Points to Remember

• Water is a renewable resource, but its availability, quality and equitable distribution make it scarce in many regions.
• India has about 4% of the world’s water resources but supports around 16-17% of the world’s population.
• Water scarcity is caused by population growth, growing agricultural demand, industrialisation, urbanisation and over-exploitation of groundwater.
• Multi-purpose river projects serve irrigation, power generation, water supply, flood control, recreation, inland navigation and fish breeding all at once.
• Examples include Bhakra Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, Tehri and Sardar Sarovar projects.
• Large dams have raised ecological, social and economic concerns — submergence, displacement, sedimentation, seismic activity and interstate water disputes.
• The Narmada Bachao Andolan opposed the Sardar Sarovar Dam over displacement and rehabilitation issues.
• Traditional rainwater harvesting methods include guls/kuls, tankas, khadin/johad and bamboo drip irrigation.
• Modern water conservation methods include rooftop rainwater harvesting, watershed management, drip/sprinkler irrigation and wastewater recycling.

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