Water: A Precious Resource

Q26. Write a note on water table.

Ans. Water table

                          i.        If we dig deeper and deeper, we would reach a level where all the space between particles of soil and gaps between rocks are filled with water. The upper limit of this layer is called the water table.

                         ii.        The water table varies from place to place, and it may even change at a given place. The water table may be at a depth of less than a metre or may be several metres below the ground.

Q27. How increasing agricultural activities are responsible for depletion of water table?

Ans. A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems such as canals are there only in a few places. Even these systems may suffer from lack of water due to erratic rainfall. Therefore, farmers have to use groundwater for irrigation. Population pressure on agriculture forces increasing use of groundwater day by day. This results in depletion of water table.

Q28. How increasing population is responsible for depletion of water table?

Ans. Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decreases the open areas like parks, and playgrounds. This, in turn, decreases the seepage of rainwater into the ground. Moreover a huge amount of water is required for construction work. Often groundwater is used for this purpose. So, on the one hand we are consuming more groundwater, and on the other we are allowing lesser water to seep into the ground. This results in depletion of water table.

Q29. Make a sketch showing groundwater and water table. Label it.

Ans.

Image from NCERT

Q30. How does water on the earth has been maintained for millions of years?

Ans. Water on the earth has been maintained for millions of years by various processes which make the water cycle. When water circulates through the water cycle it can be found in all the three forms, i.e., solid, liquid and gas—at any given time somewhere on the earth. The solid form, snow and ice, is present as ice caps at the poles of the earth, snow-covered mountains and glaciers. Liquid water is present in oceans, lakes, rivers, and even underground. The gaseous form is the water vapour present in the air around us. The continuous cycling of water among its three forms keeps the total amount of water on the earth constant even when the whole world is using it.

Q31. Explain the factors responsible for the depletion of water table.
Or
Why water is getting scarce?

Ans. Factors responsible for the depletion of water table are:

Increasing population - Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decreases the open areas like parks, and playgrounds. This, in turn, decreases the seepage of rainwater into the ground.

Increasing industries - Water is used by all the industries. The number of industries is increasing continuously. Water used by most of the industries is drawn from the ground.

Agricultural activities - A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems such as canals are there only in a few places. Even these systems may suffer from lack of water due to erratic rainfall. Therefore, farmers have to use groundwater for irrigation. Population pressure on agriculture forces increasing use of groundwater day by day. This results in depletion of water table.

Mismanagement of water resources – Leakage in water supply pipes and a lot of water gushing out of the pipes leads to wastage of precious water. Mismanagement or wastage may take place at the level of individuals also. Due to lack of water harvesting techniques water did not get replenished. Thus, results in depletion of water table.