This well is a type of deep well, tapping ground water from one or several confine aquifers lying under surface
inserted in the ground.
The parts of the pipe which are hollow and do not have any slots at this surface are known as blind pies.
he parts of pipe that have slots at their surface are known as strainer pipes or perforated pipes.
Thus a tube well consists of strainer pipes as well as blind pipes.
There are several types of strainers or perforated pipes which have been explained later in this chapter
The discharge of tube well is several times more than open well. The reasons of greater discharge are the following:
Tube wells can tap several water bearing stratum.
Water can seep into the tube well with several times more velocity than the critical velocity of flow in the case of open well.
This becomes possible because strainer pipes allow only water to pass through and no sand particles.
There is no danger of well being subsided.
Flow in the well being radial and that too from several water bearing layers, the cross-sectional area contributing water to well becomes quite large and thus quite large discharge can be obtained from the tube well.
Tube wells may be constructed by the government or by the individual farmers.
The average yield from a tube well is of the order of 40 to 50 lit/sec.
Tube wells have been installed to give yield as high as 200 to 250 lit/sec.
The depth of the tube wells may vary from 20 m to as high as 500 m.
The diameter of the bore hole is kept 60 cm for top 60 mdepth.
Tube wells can be easily installed in such soils and are very useful for irrigation.