Well types and the yield   ...

Well types and the yield

 

Dear Munchege, type of well do not have anything to do with the water yield. Water yield is depend on the type of aquifer. A well is merely an extraction structure. Choice of the type of a well will depend on factors like depth of the aquifer, availability of technology for its construction, cost and convenience. Dug wells are ideal groundwater extraction structure for shallow unconfined aquifers. These structures are preferred by farmers not only because these have considerable storage capacity but also can be constructed and deepened in phases using local expertise.A dug cum bore well is ideal when a confined aquifer occurs within a reasonable depth below the water table aquifer which is already being tapped through a dug well. When the existing confined aquifer is tapped through a vertical bore drilled at the bottom of the dug well, the chances are that the water level from the confined aquifer which occurs under hydrostatic pressure will rise and flow into the existing dug well. Water can then be pumped out conveniently from the dug well.Tube wells are most ideal for tapping high yielding confined granular aquifers occurring at considerable depths. Tube wells are also convenient for tapping groundwater from a thick unconfined granular aquifer with deep water table. Tube wells are also known to yield considerable quantity of water from sandstone and limestone aquifers occurring within multilayer formations and deep seated fractures in granitic rocks under favourable geological conditions.