Explicit Aquifer Diffusivity Estimation Using Linearly Varying Stream Stage

For a stream fully penetrating an unconfined aquifer, different approaches are available to estimate aquifer diffusivity. However, these approaches involve an interpolation of tabulated values or type-curve matching. Certain solutions also require curve fitting in order to compute hydraulic gradient at the stream-aquifer interface. Thus, in these approaches it is possible to incur errors. An alternative is to develop explicit equations of aquifer diffusivity that may not require any sort of curve fitting to extract hydraulic gradient or interpolation of tabular values. For a linearly varying stream stage, it has been possible to develop such an alternative approach. The present study develops an explicit relationship for the estimation of aquifer diffusivity using the available series or tabular solutions in the literature. An error analysis indicates that the proposed equation is capable of estimating the point-aquifer diffusivity within a maximum error of 3%.