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civil engineering-->>Sources of Fresh water & Factors affecting selection of water source



Sources of Fresh water 

Flowchart of the sources of clean drinking water
Sources of Water

The quantity of water required for a community depends upon:
  1. Forecasted population
  2. Types and variation in demand (e.g. seasonal variation)
  3. Maximum demand (Per day/Per month)
  4. Fire demand
  5. Rural demand and supplies
  6. Appropriate / Available technology

Main sources of water are

  • Surface water sources: Lakes impounding reservoirs, streams, seas, irrigation canals
  • Ground water sources: Springs, wells, infiltration wells
Above are the common sources of clean drinking water, other different sources of drinking water are

Merits of ground water sources
  1. Being underground, the ground water supply has less chance of being contaminated by atmospheric pollution.
  2. The water quality is good and better than surface source.
  3. Prevention of water through evaporation is ensured and thus loss of water is reduced.
  4. Ground water supply is available and can even be maintained in deserted areas.
  5. The land above ground water source can be used for other purposes and has less environmental impacts.

Demerits of ground water source

  1. The water obtained from ground water source is always pressure less. A mump is required to take the water out and is then again pumped for daily use.
  2. The transport / transmission of ground water is a problem and an expensive work. The water has to be surfaced or underground conduits are required.
  3. Boring and excavation for finding and using ground water is expensive work.
  4. The modeling, analysis and calculation of ground water is less reliable and based on the past experience, thus posing high risk of uncertainty.



Factors affecting selection of water source

Quantity of water:

The quantity of water available at the source must be sufficient to meet various demands and requirements of the design population during the entire design period. Plans should be made to bring water from other sources if the available water is insufficient.

Quality of water:

The water available at the source must not be toxic, poisonous or in anyway injurious to health. The impurities should be as minimum as possible and such that, can be removed easily and economically.

Distance of water supply source:

The source of supply must be situated as near to the city as possible. Hence, less length of pipes needs to be installed and thus economical transfer and supply of water.
The source nearest to the city is usually selected.

Topography of city and its surroundings:

The area or land between the source and the city should not be highly uneven i.e. it should not have steep slopes because cost of construction or laying or pipes is very high in these areas.

Elevation of source of water supply:

The source of water must be on a high elevation than the city so as to provide sufficient pressure in the water for daily requirements. When the water is available at lower levels, then pumps are used to pressurize water. This requires an excess developmental and operational tasks and cost. It may also have breakdowns and need repairs.

Water quality

  • Impurities present in water and their health significance
  • Water quality standards set by U.S and W.H.O
  • Water quality tests

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