Tool for Estimation of Additional Drawdown Due to Partially Penetrating Wells in Confined and Semi-Confined Aquifers

This paper presents a simplified approach for estimating the additional drawdown due to partially penetrating wells in confined and semi-confined aquifers. Hantush's Equation usually provides acceptable representation of the associated flow field, should this equation be properly solved. An interactive MATLAB -based computational program has been developed and verified to provide the analytical solution for the later equation. Results are projected as standard design curves which can be used to determine the total and additional drawdown due to partial penetration for semi-confined and confined aquifers, respectively. Empirical formulae, commonly used to calculate the additional drawdown in case of steady state flow for confined aquifers are also discussed, and compared with the analytical solution, showing significant differences in many cases. A proposed design chart for steady flow in confined aquifers, along with two families of curves; one for steady flow in leaky aquifers and the other for transient conditions, are thus recommended for well design purposes.