Exercise 

I. 

1.

Ans: potable water.

2. 

Ans: depletion of water table

3. 

Ans: rain

4. 

Ans: replenishes groundwater

5. 

Ans: drought

II.

1. X

2. ✓

3. X

4. ✓

5. ✓

6. X

III.

1. 

Ans: Natural resources like water and air which are constantly renewed through rapid natural cycles are called renewable natural resources.

2.

Ans: Solid state:- ice

Liquid state :- water

Gaseous state:- water vapour

3. 

Ans: Water that can be safely used for human consumption is called potable water.

4.

Ans:- Two sources of fresh water are (a) rain (b) aquifer.

5. 

Ans: The level of groundwater is called water table.

6.

Ans: Two drought prone regions in india are Rajasthan, Gujrat.

IV. 

1.

Ans: Rainwater harvesting and buliding check dams can replenish the groundwater.

2.

Ans: Rainwater harvesting is an old method of conserving water. It is done by collecting rainwater from the rooftops and storing in in tank for various household purposes. Moreover the water can be released in underground tank from where the water will seep into the ground increasing the groundwater level.

3.

Ans: Large dams are built on rivers to prevent rainwater from flowing away directly into the sea. Water stored in dams is supplied to nearby cities and towns through pipelines.

4.

Ans: The dams which are built on river in the path of its flow are called check dam. These dams slows down the flow of water and allow the water to percolate into the soil raising the water level.

5.

Ans: The drip irrigation system supplies water drop by drop near the roots of plants. Since water is supplied drop by drop, so it doesn't cause waterlogging. Therefore it doesn't shift plant nutrients deeper in the soil and retains soil fertility.

V.

1. 

Ans: The causes of groundwater depletion are:- 

  • Increase in population
  • Increase in industries
  • Agricultural activities
  • Water pollution
Increase in population:- The increasing population is becoming a threat to the world, to the mankind. The ever increasing population needs more houses to live more offices to do work, more schools, more shops and more roads. This construction activities need a huge supply of water. Moreover the demand of drinking water has also increased.  The water on the surface is not enough to meet the needs. Hence more and more water is being drawn from underground sources. Hence the groundwater is depleting day by day with the increase of population.

2.

Ans: The water distribution is uneven in our country. The amount of water in a region depends on the rain it receives. Therefore the uneven distribution of water is seen all over the world.

Our country is very vast. The rainfall varies from place to place. The region which receives less rainfall has less potable water. In these regions drought are seen. Some regions receive excess rainfall. This causes flooding. 

3.

Ans: Water pollution is very dangerous. The sources of fresh water like river, pond, lake are being contaminated due to the water pollution. Including plant lives, the marine lives and the animals are getting serious threat because of water pollution.

The main reasons of water pollution are:

  • Improper sewage facilities
  • Industrial pollution
  • Improper agricultural practices
  • Religious and social practices
Improper sewage facilities:- Many towns and cities in India do not have an efficient watwr sewage system. Most of the sewage flows into the rivers.

Industrial pollution:- Chemicals and industrial wastes drain into the rivers. These wastes are harmful not only to the different life forms that live in the rivers but also to the human beings.

4.

Ans: Water is one of the basic necessities for every living being and we cannot imagine a life without water.

Conserving water helps us by supplying more amount of water for longer usage. It has become necessary in all areas because these natural resources are reducing along with the increasing population and their usages.