Inverse Analysis of Hydraulic Conductivity of the Layer ⑦ Sandy-Pebble Aquifer in Beijing

Hydraulic conductivity is a key hydrogeological parameter in groundwater seepage analysis and dewatering design. Hydraulic conductivity directly affects the prediction accuracy of groundwater drawdown and dewatering performance. Field single-well and multi-well pumping tests were combined with a three-dimensional unsteady seepage model established using Visual MODFLOW Flex 6.1. An inverse analysis of hydraulic conductivity was conducted for the ⑦ confined sandy-pebble aquifer. The results show that groundwater drawdown during the single-well pumping test was concentrated around the pumping well and decreased with distance. Under multi-well pumping conditions, stabilized drawdown exceeded 15 m at several northern and western observation wells, while eastern and southern wells mainly showed 8–11 m. The single-well inversion yielded a local-scale equivalent hydraulic conductivity of 28.75 m/d, with a mean relative error (MRE) of 3.46%. This value was subsequently used as the initial parameter for evaluating the applicability of a homogeneous hydraulic conductivity under multi-well pumping conditions. The final engineering-scale zonal parameterization comprised an equivalent hydraulic conductivity of 28.75 m/d in the western zone, retained from the single-well inversion, and 90.00 m/d in the eastern zone, obtained through zonal calibration. The resulting calibration MRE was 3.02%. Compared with the homogeneous model, the zonal model achieved closer agreement between simulated and measured drawdowns under the tested multi-well pumping condition, indicating improved calibration performance in representing the observed spatial variation in groundwater response.