4.11.1. Overpumping In the ovrpumping method, the well is pumped at a discharge rate higher than the discharge rate of the well during its normal operation. The logic of the method is that any well which can be pumped sand-free at a high rate can be pumped sand-free at a lower rate. It is the simplest method of developing wells. However, the development by this method is not effective and the developed well is seldom efficient. The aquifer material is also not fully stabilised. This incomplete development is due to the following reasons:
(i) Water flows in only one direction and some sand grains may be left in a bridged condition. The formation is thus partially stabilised.
(ii) Most of the development takes place in the most permeable zones of the aquifer which are usually closest to the top of the screen. Therefore, less development takes place in the lower layers of the aquifer.
Besides, this method generally uses the pump intended for regular use during the normal operation of the well. Pumping of silt-laden water at higher rates can reduce efficiency of the pump.
