Inside- Water- A precious resource.

  

Inside Q & A: Chapter-16, class-VII, NCERT Water- A precious resource.

I1. Why we celebrate World Water Day every year?

Ans: 22 March is celebrated as the world water day. We celebrate water day every year to attract the attention of everybody towards the importance of conserving water.

I2. What is the recommended amount of water per person per day in United Nations?

Ans: The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining proper hygiene is a minimum of 50 litres per person per day. This amount is about two and a half buckets of water per person per day.

I3. Why Earth appears blue from space?

Ans: Our Earth is called blue planet because about 71% of the earth’s surface is covered with water.

I4. In what kind of sources does all the water on the earth is contained?

Ans: Almost all the water on the earth is contained in the seas and oceans, rivers, lakes, ice caps, as groundwater and in the atmosphere.

I5. What is freshwater?

Ans: The water that is fit for use is freshwater. Example: Ground water.

I6. What is water cycle?

Ans: The continuous cycling of water among its three forms to keep the total amount of water on the earth constant even when the whole world is using it, is called water cycle. 

I7. What are the three forms of water found during water cycle?

Ans: 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.

I8. How water is distributed in different forms on the surface of the earth?

Ans: 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.

I9. What is the indication of the presence of ground water under the soil?

Ans: If we dig a hole in the ground near a water body we may find that the soil is moist. The moisture in the soil indicates the presence of water underground.

I10. Define water table.

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

I11. Define Groundwater.

Ans: The water found below the water table is called groundwater.

I12. What is the source of groundwater? OR How groundwater gets recharged? OR What is Infiltration?

Ans: The rainwater and water from other sources such as rivers and ponds seeps through the soil and fills the empty spaces and cracks deep below the ground. The process of seeping of water into the ground is called infiltration. The groundwater thus gets recharged by this process.

I13. What is an aquifer?

Ans:. At places the groundwater is stored between layers of hard rock below the water table. This is known as an aquifer.

I14. Write some reasons behind water table depletion.

Ans:. Water table may go down if the water is not sufficiently replenished. This may happen due to many reasons:

(I) Increase in population,

(II) industrial and agricultural activities are some common factors affecting water table.

(III) Scanty rainfall is another factor that may deplete the water table.

(IV) Yet another factor affecting water table could be deforestation and decrease in the effective area for seepage of water.

I15. When depletion of water table can happen?

Ans: Water drawn from under the ground gets restored by seepage of rainwater. The water table does not get affected as long as we draw as much water as is replenished by natural processes. However, water table may go down if the water is not sufficiently replenished.

I16. Discuss some factors depleting water table.

A) 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.

 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.

B) Increasing industries

Water is used by all the industries. Almost everything that we use needs water somewhere in its production process. The number of industries is increasing continuously. Water used by most of the industries is drawn from the ground.

C) 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.

I17. Why water is unevenly distributed in the earth?

Ans: The distribution of water over the globe is quite uneven due to a number of factors. Some places have good amount of rain and are water-rich. On the other hand, there are deserts which have scanty rainfall. 

I18. How civic authority can manage water wastage?

Ans: In many places a regular supply of water is provided by a well-planned pipe system. When the civic authorities supply water through pipes not all of it may reach the destination. You might have seen water supply pipes leaking and a lot of water gushing out of the pipes. It is the responsibility of the civic authorities to prevent such wastage of precious water.

I19. How mismanagement or wastage of water takes place at individual level?

Ans: Mismanagement or wastage may take place at the level of individuals also. All of us, knowingly or unknowingly, waste water while brushing teeth, shaving, bathing, washing and during many other activities. Leaking taps is another source of huge water wastage.

I20. What is rainwater harvesting or water harvesting?

Ans: Rainwater harvesting is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or a reservoir with percolation, so that it seeps down and restores the ground water.

I21. What is bawri?

Ans: We have at many places in India an age old practice of water storage and water recharge like the bawris. Bawri was the traditional way of collecting water.

I22. What is drip irrigation? OR How drip irrigation helps to reduce water wastage?

Ans: Drip irrigation is a technique of watering plants by making use of narrow tubings which deliver water directly at the base of the plant.

I23. What role we can play to minimise the wastage of water? OR Write some water-wise habits to minimise the wastage of water.

Ans:.

• Open the tap only when in use.

• Never leave the tap water open when not in use.

• Try to use bucket and mug while bathing.

• Mop the floor instead of washing.

• Use drip or micro-drip irrigation in fields.

• Never play with water because u are wasting it.

I24. What would be the effect of water scarcity on plants?

Ans: We know that plants need water to get nutrients from the soil to prepare their food. If water is not available to plants , the green character of the planet shall be lost. This may mean the end of all life, for a world without plants shall mean no food, no oxygen, not enough rain, and innumerable other problems.