Effect Mechanistic of Partially Penetrating Well on Single-Well Push-Pull Tests for Groundwater Velocity Estimation

For the purpose of analyzing the influencing mechanism of partially penetrating well on single-well push-pull (SWPP) tests, this study employed COMSOL Multiphysics to develop a numerical model of SWPP test, in which the impacts of the length and location of screen on breakthrough curves (BTCs) were investigated. Meanwhile, a laboratory experiment of SWPP test with partially penetrating well was conducted, verifying the reliability of the proposed model by fitting the observed and simulated BTCs. The results show that a shorter screen length leads to a lower concentration of BTC in the early stage; meanwhile a shorter unscreened segment near the top of aquifer results in a lower concentration in the early stage. Additionally, the error analysis of parameter inversion indicates that the numerical model is quantified for the estimations of groundwater flow velocity, porosity and dispersion by fitting BTCs. Overall, the complicated flow field in the vicinity of partially penetrating wells leads to a non-uniform spatial distribution of solute, which has a significant effect on the BTCs and increases the parameter inversion error if using the traditional fully penetrating well model. Nevertheless, the SWPP test model developed in this paper has high fitting accuracy and can be applied to SWPP test under partially penetrating conditions.