Hydraulics of a Drainage Well Fully Penetrating a Leaky Aquifer through a Multisection Screen

The authors develop a transient semianalytical solution for evaluating the hydraulic head distribution in a leaky aquifer under constant surface-ponding conditions while draining through a fully penetrating multisection screen of an injection well. The authors use integral transform techniques such as Laplace and finite Fourier cosine for solving the said problem analytically. The solution in the Laplace domain is inverted to the time domain numerically. The authors test the performance of the derived semianalytical solution by comparing its results with field data. Subsequently, they use the solution to evaluate the hydraulic head distribution within the flow medium for a drainage event. Analyses show that the hydraulic head distribution within the radius of partial screening influence ($R_{ps}$) in the aquifer is controlled by both the radial distance from the well and the monitoring depth but only by the radial distance beyond $R_{ps}$. Further, the $R_{ps}$ does not depend on the screen sections’ lengths and positions within the fully penetrating aquifer. In addition, the results of using a multisection screen are not comparable to the single-section screen (irrespective of its position within the aquifer), having the length equal to the sum of screened depths of the multisection screen. Finally, the authors propose to use the solution derived in the present study for computing hydraulic head distribution in the flow medium specifically within $R_{ps}$ (i.e., two-times the aquifer thickness).