Two Marks Questions with Answers

TWO MARK QUESTION AND ANSWERS

 

1. What are the objectives of water supply scheme?

(i) To supply safe and wholesome water to consumers

(ii) To supply water in adequate quantity

(iii) To make water easily available for encouraging personal and household cleanliness.

 

2. Enumerate the components of a water supply scheme.

Collection works (intake structures), Treatment works (sedimentation tanks, sand filters), Transmission works (pipelines), Distribution works (storage reservoirs, pumps).

 

3. What is Design Period?

The future period for which provision is made in the water supply scheme or for which the components of a water supply system are designed is called as design period. Normally it is considered as 20 to 40 years. Eg: Design period for storage dams - 50 years, water treatment units - 15 years.

 

4. What are the factors governing the design period?

The design period is chosen based on the following criteria:

i) Useful life of pipes, equipment and structures.

ii) The anticipated rate of growth. If the rate is more, design period will be less.

iii) Availability of funds. The rate of interest on borrowing and the additional money invested.

iv) Efficiency of component units. The more the efficiency, the longer will be design period.

 

5. What are the methods of population forecasting?

• Arithmetic increase method

• Geometric increase method

• Incremental increase method

• Simple graphical method

• Master plan or zoning method

• Logistic curve method

 

6. What are the assumptions in an Arithmetical Increase Method to forecast population?

The increase in population from decade to decade is assumed constant ie., rate of change in population dP/dt is constant.

 

7. What are the assumptions in an Geometrical Increase Method to forecast population?

The percentage increase in population from decade to decade is assumed constant

8. List out the various water demand encountered in society?

• Residential or Domestic demand,

• Industrial Demand,

• Institutional Demand

• Commercial demand,

• Fire demand,

• Demand for Public Use

• Water losses

 

9. What are the factors affecting per capita demand?

The factors affecting the per capita demand are :

• Climatic conditions

• Size of city

• Quantity of water

• Pressure in supply

• System of supply

• Cost of water

 

10. Mention the various sources of water supply?

Surface water sources - Lakes, Ponds, Streams & Rivers, Impounding Reservoirs

Sub surface sources — Springs infiltration galleries infiltration wells wells tube.

11. Distinguish between Shallow and deep well?

Shallow well

• A shallow well is one where the source of water is an (410 primary unconfined aquifer

• Yield of shallow wells is comparatively less

Deep well

• A deep well is one which is having water supply from a confined aquifer

• Yield of deep wells is more than shallow wells

 

12. What are springs? What are the types of springs?

The natural outflow of ground water at the earth surface is called as springs.

Gravity springs, Surface springs and Artesian springs.

 

13. What are the factors governing the selection of a particular source of water?

• Quantity of available water

• Quality of available water

• Distance of the source of supply to the distribution area

• General topography of the intervening area.

• Elevation of the source of supply.

 

14. State the purpose of carrying out water quality characterization?

• To determine the physical, chemical and biological characteristics of surface and ground water sources

• To analyze whether the water quality parameters meet the Standards laid by legislative authorities.

• To recommend suitable water treatment methods.

• To determine the efficiency of the treatment methods

• To supply safe and wholesome water to the consumers

 

15. Give the maximum acceptable limit of the following for the public drinking water (a) Colour (b) pH (c) Chlorides (d) Sulphates

Colour - 5,

pH - 7 to 8.5

Chlorides - 200 mg//l

 Sulphates - 200 mg/l

 

16. What are the acceptable quality standards as per BIS 10500: 1983 for flouride and nitrates?

Flourides - 1 mg/l, Nitrates - 45 mg/l

 

17. What is an intake?

The intake or intake works comprises of a structure placed in a surface water source to permit the withdrawal of water from the source and then to discharge into an intake conduit through which it will flow into the water supply system.

 

18. Brief the function of intake structure?

• The main function of intakes is to provide highest quality of water from source.

• To protect pipes and pumps from damaging or clogging by wave action, floating bodies and submerged aquatic lives

• To help in safely withdrawing water from the source over predetermined pool levels and then to discharge this water into the withdrawal conduit

 

19. What are the types of intake according to their position?

• River Intake

• Reservoir Intake

• Lake Intake

• Canal Intake

* Submerged Intake

* Exposed Intake

 

20. Differentiate between Wet Intake and Dry Intake?

Wet Intake

In this intake structure, water is found in the intake tower (well) as well as the intake conduit.

Difficult to do inspection and repair works.

Dry Intake

In this intake structure, water enters only inside the intake conduits. The intake well or tower is dry.

Easy inspection and repair.

 

21. What are the factors governing the location of intake?

• It should be nearer to the treatment plant

• It should never be located near the sewage disposal points

• Water should be available even during the worst conditions

• Located on the upstream of rivers

• It should not be located near the navigation channel