New Analytical Expressions for Two-Dimensional Aquifer Adjoining with Streams of Varying Water Level

This research presents new analytical expressions to analyze interactions between streams of varying water level and a confined aquifer. The stream water level is assumed to vary exponentially with time. The expressions are obtained by means of Laplace and Fourier transform methods and the results are verified with those obtained from MODFLOW. In fact, we derive a new analytical expression for predicting of the groundwater level and flow rate in a confined aquifer between two streams of varying water level at the north and the right boundaries and two constant head boundaries at the left and the south ends. Also, a numerical example is used to investigate about the aquifer response to stream water level changes. Therefore the effects of variation water level of each stream on the flow rate at the left and the south boundaries and also at four points of the aquifer are discussed. Finally, some other new analytical expressions are also deduced for other types of boundary conditions.