1. How much of the earth’ surface is covered with water?

About 3/4^th of the earth’s surface is covered with water.

2. Why is there water scarcity when 3/4^th of the earth’s surface is covered with water?

Although 3/4^th of the earth’s surface is covered with water, about 96.5% of it exists as ocean water. Fresh water accounts for only 2.5% of the total water resources. About 70% of this fresh water exists in glaciers and ice sheets.

The availability of fresh water varies over space and time depending upon the availability of annual precipitation. Other factors that lead to water scarcity are over exploitation, excessive use and unequal access to water resources among members of different social groups.

3. Define water scarcity

Water scarcity is the lack of availability of sufficient water to meet the demand for water consumption within a region.

4. How do increasing number of industries exert pressure on existing fresh water reserves?

Industries use water and also need electricity to run their operations. Much of the electricity is produced from hydro-electric power projects. For example, in India, hydro-electric power projects contribute 22% of the total electricity generated. These power projects deplete the ground water.

In addition, industrial effluents pollute rivers and lakes making them unusable.

Industries also use water as a major coolant for their operations.

5. Explain the ill-effects of industrialisation and urbanisation on water resources.

Industrialisation and urbanisation are major causes of water scarcity. Industries are heavy users of water. Various industrial processes require water. Their machines also use water as a coolant. In addition, industries require electricity and much of it is produced by hydro-electric power projects. All these factors increase the consumption of water and lead to water scarcity.

Rapid urbanisation is another cause of water scarcity. Urban centres have large and dense populations that consume a large amount of water on a regular basis. Most housing societies have their own groundwater pumping devices and this leads to the depletion of underground water.

6. It is essential to conserve and manage our water resources. Explain with examples.

Growing population

As our population is growing, our demand for food also increases. In order to produce more food more areas need to be irrigated and this leads to greater consumption of water. Groundwater levels are already falling because farmers are digging tube wells for watering their crops.

Over exploitation of water resources

The growing population needs more food and more electricity. In India, 22% of the total electricity is generated by hydro-electric power projects. This aggravates the problem of water scarcity.

Industrialisation

Industries are heavy users of water. Rapid industrialisation not only increases the consumption of water but also causes rivers and lakes to be polluted.

Since it is impossible for humans to survive or industries to operate without water, it is imperative to save the existing water resources from further depletion and contamination.

Multi-purpose river projects and integrated water resources management

1. Bhakra Nangal Dam is on river …………………………..

Satluj

2. Sardar Sarovar Dam is on river ………………………….

Narmada

3. Koyna Dam is on river ……………………………..

Krishna

4. Who said that dams are the temples of modern India?

Jawaharlal Nehru

5. Tehri Dam is on river ……………………………

Bhagirathi

6. In which state is Tehri Dam located?

Uttarakhand

7. Explain the consequences of changing crop pattern due to irrigation

India’s population is increasing and as such the demand for food has also increased. In order to cater to the growing demand for food, farmers are now growing two or three crops per year. Earlier they depended on the rains and could grow crops only during the rainy season. Now the government is giving them loans to dig tube wells and buy pump sets so that they can irrigate their land throughout the year. As growing several crops a year reduces the fertility of the soil, farmers are using fertilizers to increase yield. Unfortunately, fertilizer mixed water and soil contaminate canals and other bodies. Also, excessive irrigation using groundwater pumping devices has caused groundwater levels to fall.

8. Describe the aim of Narmada Bachao Andolan

Narmada Bachao Andolan is a Non-Governmental Organization that mobilized tribal people, farmers, environmentalists and human rights activists against the construction of the Sardar Sarovar Dam across river Narmada in Gujarat.

Initially they focused on the environmental issues that would arise due to the submerging of trees under water after the construction of the dam.

Today they work to ensure that the poor people displaced by the dam get full rehabilitation facilities from the government.

9. Mention the advantages of multi-purpose river projects.

Multi-purpose river projects were launched after independence with the objective of conserving water resources and leading the nation to the path of growth.

India’s first Prime Minister Jawaharlal Nehru proclaimed that dams were the temples of modern India as they would facilitate the development of agriculture and give a boost to the rural economy and at the same time they would aid rapid industrialisation and ensure the growth of urban economy.

Dams were built to impound rivers and rainwater so that the stored water could be used later to irrigate the farmlands. In addition, they control floods at the time of excessive rainfall.

Another advantage is that hydro-electricity can be generated from multi-purpose river projects to run homes and industries.

10. Highlight any three hydraulic structures as a part of water management programmes in ancient India

In the first century of BC, Sringaverapura near Allahabad had good water harvesting system to channel the flood water of river Ganga.

Dams, lakes and irrigation systems were extensively built during the time of Chandragupta Maurya.

Sophisticated irrigation systems have also been found in Kalinga, Nagargunakonda (Andhra Pradesh), Kolhapur (Maharashtra) and Bennur (Karnataka)

Bhopal lake built in the 11^th century was one of the biggest artificial lakes of that time.

11. What is a multipurpose river valley project? Mention some benefits of it.

A multi-purpose river valley project involves the construction of large dams that serve several purposes in addition to impounding the water of a river.

The major objectives of such projects are:

• Provide irrigation water to enhance food production in the country.
• Regulate river flow and ensure adequate supply of water during dry months.
• Supply water for domestic and industrial purposes.
• These projects involve several small, medium and large dams on rivers and help to generate electricity.

12. Why have multi-purpose river projects come under great scrutiny and opposition?

Multi-purpose river projects have come under criticism for the following reasons.

Controlling and damming rivers affect their natural flow. Consequently, sediment cannot flow easily and this leads to excessive sedimentation at the bottom of the reservoir.

These projects affect the habitat of aquatic beings living in the river. Dams also fragment rivers making it difficult for aquatic animals to migrate especially for spawning.

The reservoirs built on the floodplains cause the existing vegetation and soil to submerge and decompose.

13. Why are dams called multi-purpose projects.

Earlier the only purpose of building dams was to impound the river so that water can be conserved for irrigation later.

Now in addition to conserving water for irrigation, dams serve several other purposes. For example, these dams help to produce electricity, provide water for domestic use, control flooding, offer recreational opportunities, facilitate inland navigation and support fish-breeding.

Hence, they are called multi-purpose river projects.