Abstract
This paper describes a theoretical consideration about the effect of pumping of fresh water on the motion of seawater interface already formed in a confined aquifer. At first, the differential equation of interface is derived from the fundamental equation of confined water in the case where the aquifer is impervious at its lower surface and has the pumping well distributed continuously at its upper one, and is solved under the conditions that the constant supply of fresh water is given at a fixed point of the upper course and the pressure of water is taken as a hydrostatic distribution. From this solution, it is found that the toe of the interface is moved backward or forward by the inerease of fresh water inflow or of the amount of pumping, respectively and is also, moved more back according to the more concentration of pumping intensity on the lower course of aquiter. Finally, an example is shown for the method through which, in the coastal region where the residual flow of fresh water into the sea exists, this residue is fully pumped up within the limit that the present toe of interface remains immoved.
