Tidally induced groundwater fluctuations in aquifers located near the Kenai River, Alaska (Alaska, Kenai River)

Defining the influence of ocean tides on coastal rivers and aquifers is useful for many engineering problems, including analysis of groundwater and surface water interactions. This study shows that a correlation exists between the tides in Cook Inlet and observed groundwater fluctuations in wells near the Kenai River of Alaska. Through application of the Fourier transform, this study shows that a repeatable relationship exists between water level fluctuations in the surface water and underlying aquifers, and that there is a hydraulic exchange between the Kenai River and these aquifers. Through spectral analysis, the dominant tidal frequencies are isolated for several data sets. The inverse Fourier transform of the isolated signals returns the dominant tidal constituents for each data set on a vertically translated and common axis. When data from each aquatic system are compared, the signals are similar, but display a delay and attenuation of the tidal signal.