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Borewells are welcome innovation in groundwater technology for meeting the
domestic water supply. Most of the households in Andhra and Karnataka towns
have provision of borwells. UNICEF / Govt. of India have installed large number
of drinking water borewells operated by Special hand pumps (Mark-II, Mark-III)
capable of drawing water from depth.
B.
Semi-consolidated / Sedimentary rocks
In semi-consolidated rocks, dug wells are constructed. In favourable conditions.
Tubewells are also feasible, particularly in sandstone and limestone areas.
Tubewells
Tubewells are the most prominent groundwater structures for drawal of
groundwater. A tubewells has following important components :
1.
Casing pipe
2.
Housing pipe
3.
Slotted pipe or filter
4.
Bail plug
5.
Lifting device - pumpsets
In normal nomenclature, we say deep tubewell and shallow tubewell, as if to
indicate the depth and deeper the well, better is the discharge. It is really not
true. Discharge depends upon availability of good aquifer. Tubewells are best
defined in terms of prime mover and pumpset used for discharge. A shallow
tubewell is a well which can be run by a prime mover upto 5 hp. Such tubewells
are of low diameter upto 100 mm (4"). They do not have housing pipe. In
contrast tubewells fitted with higher horsepower prime mover, generally 15 HP
to 25 HP are heavy duty tubewells. The diameter of such tubewells are also
higher, 200 mm and above. Casing pipe is the main tubewell pipe. Housing pipe
is placed above the casing pipe and is so named because it houses the prime
mover. Slotted pipe or filter is placed against the aquifer. Bail plug is placed at
the bottom where sand from aquifer may accumulate.
