Estimating diffusivity of aquifers with sloping water tables

In many stream-aquifer systems concurrent data on river stage fluctuations and ground water levels in the adjoining aquifer can be easily obtained. This paper presents an analytical model to determine the diffusivity of such aquifers. It is assumed that the aquifer is isotropic and homogeneous with horizontal or sloping water table and one-dimensional ground water flow to or from the river in a semi-infinite few field. The fluctuations in river stages may be invariant with or linear or quadratic functions of time and may be continuous or have a finite duration If the rate of ground water recharge from the aquifer is known, then hydraulic conductivity can be estimated using Dupuit's equation. This information, along with known saturated thickness, can be used to estimate the storage coefficient or specific yield from the aquifer diffusivity computed by this model.