Unsteady equation for free recharge in a confined aquifer

Slug test solutions require instantaneous water column in the recharge well, and it consider well storage and well loss not appropriate for recharge cases. State of the art suggests recharge hydraulics, a phenomenon synonymous to mirror image of well pumping. In this background, the present paper derives fresh semi-analytical equations for confined aquifer, which simultaneously determine unsteady recharge rates at the recharge well face and rising heads in the aquifer. Such computations that are mandatory in free recharge situations may not be possible with slug test solutions. Developed solutions in a fully penetrating well include well storage, a function of aquifer diffusivity. Head loss computation is found more appropriate with friction parameter “k”, a function of Reynolds number.   Key words: Fully penetrating well, well storage, discrete kernel, friction parameter.