NCERT Solutions for Class 10 Social Science Chapter 3 - Water Resources

Answer:

Suffering from water scarcity:(c), (d)

Not suffering from water scarcity: (a), (b)

Answer:

(a) Multi-purpose projects bring water to those areas which suffer from water scarcity.

Answer:

Correct statements:

1. Multiplying urban centres with large and dense population and urban lifestyles have added to the water and energy requirements.
2. Regulating and damming of rivers affects its natural flow and sediment flow.
3. In Gujarat, the Sabarmati basin farmers were agitated and almost caused a riot when higher priority was given to the water supply in urban areas, particularly during droughts.
4. Today in Rajasthan, the practice of rooftop rainwater harvesting is on the decline because of high water availability due to the Rajasthan Canal.

Answer:

About 3/4th of the earth’s surface is covered with water, but fresh water is available in a small proportion. It is obtained from the following sources:

1. Surface run-off
2. Groundwater
3. Precipitation (in the form of Rain, snow, dew, hail, etc.)

This water available in all sources is continuously being renewed and recharged through the process of hydrological cycle. Thus, water becomes a renewable resource.

Answer:

The shortage of water, as compared to its demand, is called water scarcity. According to Falken Mark, a Swedish Expert, water scarcity occurs when the water availability is less than 1000 m3 per person per day.

Causes of Scarcity:

1. Low rainfall
2. Water scarcity occurs in drought-prone areas.
3. Variation in seasonal rainfall.
4. Over-exploitation of water.
5. Excessive use of water.
6. Unequal access to water.
7. Great demand due to growing population.

Answer:

Many river valley projects have been started for the purpose of integrated economic and social development of the river basins.

Advantages of multipurpose projects:

1. Dams are built for irrigation.
2. They generate electricity.
3. They provide water.
4. They help in industrial development.
5. They help in industrial development.
6. They help in recreation and navigation.
7. They help in fish breeding.

Many benefits are obtained simultaneously. So they are called Multi-purpose projects. Disadvantages of multipurpose projects:

1. They affect the natural flow of rivers.
2. This results in poor sediment flow and excessive sedimentation at the bottom of the reservoir.
3. It results in poorer habitats for aquatic life in the river.
4. They submerge the existing vegetation and lead to soil decomposition.
5. It also causes a large-scale displacement of the local communities.

Answer:

Rainwater harvesting is a technique of increasing the recharge of groundwater by capturing and storing rainwater. Many low cost techniques are used in semi-arid areas like Rajasthan. In Bikaner, Phalodi and Barmer, underground tanks or tankas are used for storing drinking water. They are connected to the sloping roofs of the houses through a pipe. Rainwater is stored in the tankas for three to five years. Rainwater or Palar Pani is considered the purest form of fresh water.

Answer:

In ancient India, traditional methods were used for rainwater harvesting. Even today, these methods are used to conserve water. Rooftop rainwater harvesting system is commonly practised to store drinking water. People built diversion channels like Guls and Kuls in the Himalayas. Khadins in Jaisalmer and Johads in Rajasthan store rainwater. Tankas were used to store drinking water. Underground tanks are connected to the sloping roofs of the houses to preserve rainwater.

Answer:

1. Don’t over-use water.
2. Turn the tap off, when it is not in use.
3. Reuse kitchen water for gardening.

Answer:

Since time immemorial, people were aware of the importance of preserving the natural resources like water. Hence, they devised techniques to harvest rainwater, river water, groundwater, and flood water while maintaining the ecological conditions with their water needs.

1. In hilly and mountainous regions, people built diversion channels, for agriculture, like the ‘guls’ and ‘kuls’ in the Western Himalayas.
2. To store drinking water, especially in Rajasthan ‘Rooftop rainwater harvesting’ was practised.
3. In the flood plains of Bengal, to irrigate the fields inundation channels were developed.
4. Agricultural fields in the arid and semi-arid regions, were converted into storage structures that allowed rain water to collect and moisten the soil examples are the ‘khadins’ in Jaisalmer and Johads and Tankas in other parts of Rajasthan.

Answer:

1. Krishna-Godavari water dispute between Karnataka and Andhra Pradesh.
2. Kaveri water dispute between Tamil Nadu and Karnataka
3. Krishna water dispute between Maharashtra, Karnataka and Andhra Pradesh.
4. SYL between Punjab and Haryana.
5. Indus water dispute between India and Pakistan.

Answer:

Normally, water pollution is caused through the discharge of domestic and industrial wastes into water that affects water quality. The industrial wastes, chemicals, pesticides and fertilisers used in agriculture make it more hazardous for human use. These uses have affected the quality and quantity of water in the following ways:

1. Our villages particularly suffer on account of the quality of water available for domestic use. About half of our villages are yet to be provided with safe drinking water.
2. Most of India’s rivers, especially the tributaries of the main river have become sinks of domestic and industrial wastes. The Supreme Court, in a recent judgement, described river Yamuna as the ‘City’s Drain’.
3. Today, most rivers are health hazards, threatening the health and livelihoods of many people.
4. Water contamination and deteriorating water quality have caused degradation of our natural ecosystems.
5. Over-exploitation and mismanagement of water have impoverished our resource base and caused ecological crises.