Hydraulics of a multi-section screened well while draining ponded land in a leaky aquifer

Abstract

A transient semi-analytical solution is developed for evaluating hydraulic head distribution in a leaky aquifer while draining the surface ponded water under constant-head conditions through a well having multi-section screen. Integral transform techniques such as Laplace and finite Fourier cosine are used for deriving the semi-analytical solution. Applicability of the derived solution is verified using the field data. The developed hydraulics is used to demonstrate the effect of multi-section screen on head distribution within the aquifer. A new term, radius of partial-screening influence (R ps), is introduced in the present study. The R ps of a single/multi-section screen depends on the position(s) of the screen section(s) within the aquifer. Analyses of the results show that the radial distance beyond which the influence of multi-section (m sections, say) well screen fully penetrating the aquifer (but only partially screening it) vanishes is equal to 1/m times the aquifer thickness for the screen sections that are positioned symmetrically with reference to the mid-lines of their respective aquifer portions hypothetically divided into m equal depths, whereas this radial distance ranges from 1 to 2 times the aquifer thickness for the screen having asymmetrically positioned screen section(s). Analyses for various screen thicknesses show that the prominence of the edge effect(s) of screen-section(s) increases with the increase in screen thickness.