sources of water in the civil Engineering

sources of water in the civil Engineering

1. Sources of Water
Surface sources of water:-
River & Stream.
Lakes & Ponds.
Impounded Reservoir.
Oceans.
Sub Surface Sources of water:-
Wells.
Springs.
Infiltration Galleries.

2. Surface Sources of Water:
1)In which water flows over the surface of earth.
2)Directly available for water supply.

River:
1)Most important source of water.
2)Formed due to discharge of water from many springs & streams.
3)Most of cities are settled near the rivers.
4)Perennial or non-perennial.
5)Quality of water is not reliable due to large amounts of silt, sand, etc.
6)Disposal of sewage in river is further contaminate the water.
7)River water must b properly analyzed and well treated before supplying to the
public.

3. Streams:
1)In hilly regions streams are formed by the runoff.
2)The streams are flow in valleys and are the main source of water to villages of
hills.
3)The quality of water is good except first runoff.
4)Small streams are not suitable but perennial streams may be used by providing
barrages across them.
Lakes & Ponds:
1)A natural large size depression formed within the surface of the earth.
2)Difference between pond & lake is only that of size.
3)Quantity of water in lake depends on catchment area, annual rainfall, porosity
of ground, etc.
4)Lakes at high altitudes contains almost pure water which can be used without
any treatment.
5)The quality of large lake is good than that of small lakes.

4. Impounded Reservoir:-
1)A barrier in the form of a dam may be constructed across the river, so as to
form a pool of water on the upstream side of river.
2)This pool or artificial reservoir is known as impounded reservoir.
3)The quality of water is not much different from that of natural lake.
4)Objective is to store water & stabilize flow of water to fulfill the need of water
in summer season.
5)Main source of water for big cities.

5. Sub Surface Source of Water:
1)The water which gets stored in the ground water reservoir through infiltration,
etc. is known as underground water or subsurface water.
2)This water is generally pure because it undergoes natural filtration during the
percolation through the soil pores.
3)Less contaminated but rich in in dissolved salts, minerals, etc.
Wells:
These are the artificial structure created by the excavation of trends into a
ground.
Depending upon depth & method of construction wells are classified.
1)Shallow well
2)Deep well
3)Tube well

6. Shallow Well:
1)These are constructed in the uppermost layers of earth’s surface.
2)Diameter varies from 2m to 6m.
3)May be lined or unlined.
4)Quantity of water available from shallow well is generally is limited.

7. Deep Well:
Obtain their quota of water from an aquifer below an impervious layers.
Water consist of dissolved salts & become hard.

8. Tube Well:
1)It is deep well having diameter of 5cm to 20 cm.
2)Obtains its quota of water from number of aquifer.
3)Depth of well depends on the quality of water required.
4)Usually depth is about 30 to 50 m but it may be even go upto 300m is some
dry areas.

9. Springs:
1)When ground water reappears at the ground surface it is called as springs.
2)It is formed near the hills.
3)Quantity of water is provided is less, hence suitable for small town.
4)Certain springs sometimes discharge hot water due to the presence of sulphur
in them.
5)Springs are usually formed under three general condition of geological
formation as below:
A.Artesian springs
B.Gravity springs
C.Surface springs

10. Artesian Springs:
The ground water comes to the surface under pressure.
This formed due to presence of crack in impervious layer.
These kind of source provide uniform quantity of water through out the year.

11. Gravity Springs:
This springs develop due to overflowing of the ground water.
When the ground water table rises high & such a springs is known as gravity
spring.
Flow from such a spring varies with rise or fall of the ground water table.

12. Surface Springs:
This spring will be formed when subsoil water is exposed to the ground surface
by the obstruction of an impervious layer.
The quantity of water available is small and uncertain.
Cut off wall may be constructed to develop such a springs.

13. Infiltration Galleries:
1)Artificially constructed structure use for collecting underground water near
river, stream and lakes
2)Horizontal canal type constructed structure with hole on sides at right angle to
the direction flow of underground water.
3)Consist of open jointed perforated concrete pipes embedded in a sandy
subsurface.
4)These pipes are surrounded by aggregates.
5)Ground water percolated through aggregates into pipes & conveyed to a sump
well.