During tunnel construction in strongly developed karst terrain, water inrush hazards often occur due to the complex hydrogeological conditions, which require accurate prediction of water inflow. In this study, a dynamic modeling approach for water inflow prediction of karst tunnels using the conduit flow process (CFP) is developed that considers both karst duality and changing boundary conditions of the tunnel. The CFP model has a good agreement with field-observed hydraulic head after calibration, and the Nash–Sutcliffe model efficiency (NSE) for the CFP model is 97.3%. Numerical calculation of water inflow was conducted in a successive drilling scenario with permeability change of the surrounding rocks. Additionally, a modular three-dimensional finite-difference ground-water flow model (MODFLOW) has been applied to predict the water inflow, for comparison with the CFP model. The prediction results obtained from the CFP model are generally in close agreement with the field-observed results; the percentage errors were 13.3% and 5.4%, respectively. For the MODFLOW model, the percentage errors were 34.2% and 36.8%, respectively. The proposed CFP model is both closer to reality and more reasonable than the MODFLOW model in predictive analysis of water inflow into karst tunnels, reflecting the influence of karst conduits on the water inflow process.

In this study, an improved DRASTIC model, including the DRASTIC-LTPD model and the AHP-DRASTIC-LTPD model, with the addition of four extra evaluation factors, including land use type (L), aquifer thickness (T’), aquifer potential (P) and pollution source distance (D’), was constructed and compared to assess the groundwater vulnerability around farmland area in Shuangsheng Industrial Park, Sichuan Province, China. From the vulnerability grading charts of the traditional DRASTIC model, the improved DRASTIC-LTPD model and the AHP-DRASTIC-LTPD model, it showed that the vulnerability presented a lower level in the western and eastern farmland areas, whereas a higher level was in the central industrial park area. This result was consistent with the actual situation where groundwater recharge by rivers, regional land use, and human activities were more active in the middle in these areas. Nevertheless, the area at the same level of vulnerability varied greatly from model to model. The vulnerability index V-level region ratio calculated by the AHP-DRASTIC-LTPD model was 0, indicating that the distribution of vulnerability was smoother without the appearance of extremely good or poor conditions. From the present study, it was revealed that the AHP-DRASTIC-LTPD model could effectively reflect the impact of human activities and dilution on groundwater vulnerability. The adopted AHP method was also of high accuracy to empower the evaluation index leading to a more reliable evaluation results of regional groundwater vulnerability in comparison with the other two models. Therefore, this research could be employed as a reference for the evaluation of groundwater pollution around other similar unplanned industrial parks.

In this paper, the groundwater environment in the farmland area around a traditional industrial park in Shifang City, southwest China, was taken as the research object. Geostatistical methods with GIS technology were adopted to analyze the spatial distribution of conventional pollutants and heavy metals in groundwater and to evaluate potential ecological risks. Chemical oxygen demand (COD_Mn) and ammonia nitrogen (NH₃-N) distributions showed poor continuity and apparent spatial differentiation, which were primarily attributed to intensive anthropogenic activities (e.g., industrial discharges). The total relative hardness of (TH), SO₄²⁻, and Cl⁻ were uniformly affected by external factors, with little spatial differentiation. Concentrations of total phosphorus (TP), TH, SO₄²⁻, and Cl⁻ followed an approximately normal distribution; the peak values of detected concentrations appeared in the frequency distribution range, while COD_Mn and NH₃-N did not. Groundwater showed enrichment for various heavy metals, mainly Zn and Cu, with apparent spatial differentiation in Cr and Cu, consistent with external interference. The correlation coefficients of Cr–Cu and Cu–Pb were 0.693 and 0.629 (p < 0.01), respectively, indicating similar pollution sources. The single-factor pollution index for groundwater was Ni > Pb > Mn > Zn > Cu > Cr. Cu had a moderate potential ecological risk. The six heavy metals’ average integrated potential ecological risk index (RI) revealed that mild pollution accounted for 96.2% of the investigation area. Overall, the traditional industrial park poses a mild ecological risk to the shallow groundwater in the surrounding farmland.

The interaction between the low-permeability matrix and high-permeability conduits is a governing mechanism in karst hydrogeology, yet it remains difficult to quantify, especially under the disturbance of underground engineering. This study investigates the spatiotemporal evolution of groundwater exchange and the impact of tunnel drainage in a typical karst system in Southwest China. We developed a regional dual-permeability model by integrating GemPy for 3D geological structural modeling and MODFLOW-CFPv2 for hydraulic simulation. The model achieved a high reliability with a Pearson correlation coefficient of 0.98 between simulated and observed heads, outperforming traditional MODFLOW-Drain/River methods in capturing non-Darcy conduit flows.Simulation results under natural conditions reveal significant spatial heterogeneity: while the matrix-to-conduit recharge dominates the spatial extent (37% of the area), the conduit-to-matrix leakage dominates the total exchange volume (58%). Sensitivity analysis identifies matrix hydraulic conductivity and conduit wall permeability as the most critical factors controlling exchange intensity, whereas rainfall intensity primarily influences local flow directions rather than the overall exchange pattern. Furthermore, the study quantifies the disturbance of tunnel drainage. Tunnel construction caused a maximum groundwater drawdown of 5.44 m and a residual drawdown of 2.00 m during the stable phase. Crucially, drainage activities induced flow reversals (transforming matrix recharge zones into leakage zones) and reduced the regional exchange flux by an average of 2,987 m³/d. These findings clarify the non-linear controls on karst flow exchange and provide a robust scientific basis for groundwater management and geo-hazard mitigation in engineering-disturbed karst aquifers.