Research on Occurrence Characteristics of Karst Groundwater and Safety Thresholds for Industrial Water Extraction in the Lancun Spring Basin

Aiming at the resource and ecological issues induced by over-exploitation of Karst groundwater in the Lancun spring basin, it integrated methods including field investigation, pumping tests, and numerical simulation to systematically analyze the spatial differentiation patterns and dynamic evolution characteristics of aquifers. A three-dimensional safety threshold system for industrial water extraction, encompassing "water quantity-water level-ecology", was constructed, followed by a sensitivity analysis of the system. The results indicate that the Karst aquifers in the basin exhibit a distinct "three-zone differentiation" feature, with the Middle Ordovician limestone serving as the core water-supply horizon. By 2020, the exploitation volume of Karst groundwater had approached the critical value of allowable exploitation quantity. The safety thresholds for industrial water extraction are explicitly defined as: an annual extraction volume of 1.2366 million m³, a water level depth ≤ 200 m, and an ecological flow ≥ 7.54 L/s. Based on these researches, recommendations for industrial water extraction are proposed, including prioritizing the promotion of unconventional water source utilization, strictly regulating new water extraction projects, establishing a dynamic water level monitoring and response mechanism, and implementing artificial recharge and restoration projects.