The SVF-method incorporates a lumped parameter approach whereby the status of the aquifer, based on the
water-level fluctuations of the monitoring boreholes, is integrated and its variation with time is analysed.
By means of interpolation, the piezometric levels from the different observation boreholes are integrated to
yield the saturated volume status for the entire aquifer. An arbitrary value for the base thickness of the
aquifer is assigned, usually in such a way that the saturated volumes are always positive values. Structures
such as dykes, geological faults or watersheds usually control the boundaries of the system.
The classical hydrogeological water balance equation (on which the SVF-method is based) for a
groundwater reservoir with an impermeable base is given by