Well hydraulics of temporally varying artificial recharge with well clogging in confined aquifers

Abstract

To address the effects of well and aquifer clogging and variable injection rate on groundwater flow dynamics, an analytical model of well hydraulics is developed for the artificial recharge using a fully penetrating well. In this model, the clogging-related hydraulic conductivity of the recharged aquifer is assumed to decay exponentially with time. Meanwhile, the injection rate is considered as a sinusoidal function over time. An analytical solution is obtained by solving the model using the Hankel transform. Then, a parametric study is conducted to investigate the effect of sinusoidal-rate injection and exponentially decayed permeability on groundwater flow dynamics. The results indicate that (1) the inhibition and hysteresis in hydraulic conductivity causes the discrepancy in the distribution of hydraulic head increment (s) between the variable- and constant-rate injections. (2) The discrepancy in the distribution of s is more obvious under the injection rate with smaller frequency and larger amplitude. (3) The permeability reduction increases the hydraulic conductivity hysteresis and the discrepancies in s between the variable- and constant-rate injections. (4) The larger permeability reduction causes higher injection pressure at the wellbore and induces a larger s around the injection well but smaller one in far-field. Furthermore, a method using optimized back-propagation artificial neural network based on genetic algorithm is successively developed for aquifer parameter estimation. The findings of this study offer the better sight on the groundwater flow dynamics in confined aquifers under the combined effects of clogging-induced permeability reduction and variable-rate injection.