Tunnelling activities may significantly alter the groundwater balance in a karst aquifer, but assessment of this effect remains challenging due to the complex flow geometries and strong hydrogeological heterogeneity. In this study, based on extensive site characterization of an independent hydrogeological unit (HU) in which a deep-buried tunnel is under construction, we present a modified lumped model to evaluate the impact of tunnel construction on the discharge from the aquifer system. The lumped model consists of four interacting flow compartments and the associated water balance equations. A series of simplified models is then developed, by merging or removing some of the flow components that represent different mechanisms and relationships between recharge and discharge. The dominant hydrological processes in the HU are identified by comparing the performance of the models of different structures and by screening analysis of parameter sensitivities. It is found that the tunnel excavation captured a mean portion of 19% discharge from the aquifer system into the tunnel, which is comparable to the result predicted by 3D numerical simulations. This study evidences that as a first and simple approximation, the lumped models provide a useful tool for characterizing the dominant factors that govern the groundwater response and for evaluating the groundwater budget changes induced by anthropogenic activities such as tunnelling and underground mining in karst regions.

隧道活动可能会显着改变岩溶含水层中的地下水平衡，但是由于复杂的水流几何形状和强大的水文地质异质性，对这种影响的评估仍然具有挑战性。在这项研究中，基于正在建设深埋隧道的独立水文地质单元（HU）的广泛场地特征，我们提出了一种改进的集总模型，以评估隧道建设对含水层系统流量的影响。集总模型由四个相互作用的流动室和相关的水平衡方程组成。然后，通过合并或删除一些代表不同机理和补给与排放之间关系的流量分量，来开发一系列简化的模型。通过比较不同结构模型的性能以及对参数敏感性进行筛选分析，可以确定HU中主要的水文过程。发现该隧道开挖捕获了从含水层系统进入隧道的平均流量的19％，这与3D数值模拟预测的结果相当。这项研究证明，作为一种简单的近似方法，集总模型提供了一个有用的工具，可用于表征支配地下水响应的主要因素，并评估人为活动（例如岩溶地区的隧道和地下采矿）引起的地下水预算变化。发现该隧道开挖捕获了从含水层系统进入隧道的平均流量的19％，这与3D数值模拟预测的结果相当。这项研究证明，作为一种简单的近似方法，集总模型提供了一个有用的工具，可用于表征支配地下水响应的主要因素，并评估人为活动（例如岩溶地区的隧道和地下采矿）引起的地下水预算变化。发现该隧道开挖捕获了从含水层系统进入隧道的平均流量的19％，这与3D数值模拟预测的结果相当。这项研究证明，作为一种简单的近似方法，集总模型提供了一个有用的工具，可用于表征支配地下水响应的主要因素，并评估人为活动（例如岩溶地区的隧道和地下采矿）引起的地下水预算变化。