Response of an Unconfined Sloping Aquifer to Constant Recharge and Seepage from the Stream of Varying Water Level

This paper presents analytical solution of one-dimensional linearized Boussinesq equation characterizing unsteady groundwater flow in an unconfined aquifer, overlying an impervious downward sloping bed. At one end, the aquifer is in contact with a constant water level and at the other end; water level is rising exponentially from an adjoining stream. The aquifer also receives constant or cycle of time-varying vertical recharge. Analytical expressions for hydraulic head and flow rate in the aquifer are obtained by solving the seepage model using Laplace transform. The expressions derived here can explain sudden rise or very slow rise in the stream water related to sloping or horizontal beds and are represented under asymptotic case. Response of a short and long aquifer to the variation in bed slope, recharge rate and rise rate of the stream water is illustrated with the help of numerical examples. The sensitivity of the flow rate is also analyzed with respect to various parameters.