Modeling of multiyear water-table fluctuations in response to intermittent artificial recharge

Artificial groundwater recharge is an important component of water resources management in arid areas. Knowledge of the surface-water/groundwater interaction in a stream-aquifer system is important for sustainably managing the aquifer and obtaining the expected environmental benefits. In this study, an analytical solution of the linearized one-dimensional Boussinesq equation was obtained by using the Laplace transform; then, improved analytical models of multistage recharge were constructed on the basis of the spreading effect and delay effect to model the multiyear water-table fluctuations in a homogeneous, isotropic, unconfined aquifer under intermittent artificial recharge conditions. In addition, sensitivity analyses were performed to assess the responses of the water-table fluctuations to changes in each controlling hydrogeological parameter. To further validate the proposed method, the analytical models were applied to estimate the multiyear water-table fluctuations in the intermittent artificial groundwater recharge basin of the downstream of Tarim River, northwestern China. The results indicated that the analytical solutions and improved analytical models, which utilize the variation in the water table as a boundary condition, can explain the rise and fall of the water table within the unconfined aquifer. The accuracy of the simulation results was tested through a comparison with observations, and the results demonstrated that the models can effectively reflect the water-table fluctuations under transient recharge, spreading recharge and multistage recharge conditions. These findings can provide a theoretical basis and references for studying and modeling the water-table fluctuations under intermittent artificial recharge conditions spanning multiple years.