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Q1. Discuss how increasing population causes depletion of water table?

Solution

Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decreases the open areas like parks, and playgrounds which affects the seepage of rainwater into the ground. Also, increasing population consumes more water for all their activities. So, the increasing population ends up consuming more groundwater as well as allowing lesser water to seep into the ground. This results in depletion of water table.

Q2. What is drip irrigation? Why is this technique advantageous in regions of water scarcity?

Solution

Drip irrigation is a technique of watering plants by making use of narrow tubings which deliver water directly at the base of the plant. Water falls drop by drop just at the position of the roots. Hence water is not wasted at all. Thus, it proves advantageous in regions of water scarcity.

Q3. Name any six factors causing depletion of water table.

Solution

(i) Increase in population. (ii) Increase in industrial activities. (iii) Increase in agricultural activities and overgrazing by cattle. (iv) Scanty rainfall. (v) Deforestation. (iv) Decrease in effective area for water seepage. (vii) Saltwater intrusion. (Any 6)

Q4. (a) On digging a hole in the ground near a water body, we find the soil to be moist. Why?(b) How can we pump out the water in the aquifers?

Solution

(a) The moisture in the soil indicates the presence of underground water. (b) Water in the aquifers can usually be pumped out with the help of tube wells or hand pumps.

Q5. What is infiltration? How does it occur?

Solution

The process of seeping of water into the ground is called infiltration. 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.

Q6. How can we get water from aquifers?

Solution

Water in the aquifers can be pumped out with the help of hand pumps.

Q7. Give two disadvantages of drip irrigation.

Solution

Two disadvantages of drip irrigation are: 1. It leads to blockage of water if not filtered correctly. 2. The lifetime of tubes or pipes used in this type of irrigation may be shortened by the sun rays causing wastage of water.

Q8. When do we celebrate World Water Day?

Solution

World Water Day is celebrated on 22 March.

Q9. What do you understand by water table? Name the factors that affect water table.

Solution

The top level of the underground water is called the water table. Factors affecting water table: i. Average rainfall in that area. ii. Pumping out of groundwater.

Q10. Define infiltration.

Solution

The process of seeping of water into the ground is called infiltration.

Q11. Write any three advantages of water harvesting.

Solution

(i) Rainwater harvesting can reduce flooding in city streets. (ii) Sea water intrusion in coastal areas can be arrested. (iii) The ground water can be recharged and conserved . (iv) Rainwater harvesting can reduce topsoil loss. (v) It can improve plant growth. (Any three)

Q12. Write any four ways how individuals waste water at home?

Solution

(i) People waste water while brushing or shaving. (ii) Water flowing from taps while bathing for a long time. (iii) Leaking taps. (iv) Wasting water while washing utensils and clothes.

Q13. Does salt water intrusion affect the water table? How?

Solution

Yes. Over use of underground freshwater reservoirs often allows salt water to intrude into aquifers and affect the water table. Thus, the amount of fresh water becomes less available.

Q14. Which two natural forces may deplete the water table?

Solution

Scanty rainfall and hot winds are natural forces that may deplete the water table.

Q15. Water harvesting is the need of the hour. Justify.

Solution

Surface water is inadequate to meet our demands and we have to depend on ground water. Due to rapid urbanization, infiltration of rain water into the sub-soil has decreased drastically and recharging of ground water has diminished. Hence, there is urgent need for rainwater harvesting.

Q16. What happened to the bawris with time? Why are they being revived today?

Solution

Bawri was the traditional way of collecting water. With time the bawris fell into disuse and garbage started piling in these reservoirs. However due to acute water shortage, people in these areas began reviving these bawris and managing their water needs well, inspite of scanty rains.

Q17. List the solid, liquid and gaseous forms of water in our surrounding.

Solution

1. Solid form of water is snow and ice which is present at the poles of the Earth. 2. Liquid form of water is present in lakes, rivers, oceans etc. 3. Gaseous form of water is the water vapour present in the air around us.

Q18. Give an example of wastage of water occurring due to negligence of civic authorities.

Solution

Leaking of water supply pipes causes a lot of water gushing out of the pipes, thereby leading to wastage of water.

Q19. (a) What do you understand by rainwater harvesting?(b) Mention any two habits that can be done to save water at home.

Solution

(a) The activity of collecting rainwater directly or recharging it into ground to improve ground water storage in the aquifer is called rain water harvesting.(b)(i) Turning off taps while brushing.(ii) Mopping the floor instead of washing.(iii) Reducing flow of tap water while washing utensils.(Any two)

Q20. Why do Indian farmers have to use groundwater for irrigation?

Solution

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.

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