Influences of heterogeneity on three-dimensional groundwater flow simulation and wellhead protection area delineation in karst groundwater system, Taiyuan City, Northern China

Karstic limestone formation in Lancun spring area is one of the most important drinking water resources for Taiyuan City in Shanxi Province. The mapping of drinking water-protected areas is an effective way to protect drinking water sources. In this study, Lancun spring area in Taiyuan City was considered as a case study. Considering geological deposition and hydrogeological characteristics of this area, the stochastic idea was introduced to structural model establishment to determine the heterogeneity of karst groundwater system and clarify medium parameters. To analyze the influence of heterogeneity on groundwater flow simulation and wellhead-protected area delineation, homogeneous and stochastic hydrogeological parameter models were established and coupled with groundwater flow simulation models. Particle tracer analysis could be performed to determine capture zone. Results showed that stochastic methods could be used to generate a series of possible flow head field distributions and delineate a series of capture zones compared with homogeneous methods; thus, probability distribution was observed instead of a deterministic area. This result could provide a more scientific basis for the design and assessment of protective measures for wellhead areas in karst groundwater systems.