Karst systems present multiple challenges for the application of physically based numerical models, due to the heterogeneity and high spatial variability of their hydrogeological parameters. Some models can face conceptual limitations specific to the karst environment (like equivalent porous medium models). A new version of MODFLOW called MODFLOW-USG (UnStructured Grid) was developed and released (Panday et al., 2013) implementing unstructured grids and finite volume numerical solutions, to enable a more physically accurate modelling of karst aquifers. In this study, we tested for the first time the abilities of MODFLOW –USG with CLN within on a small Irish catchment feeding the spring of Manorhamilton, located in county Leitrim, Ireland. In order to create a numerical model of this karst system, we developed a methodology combining 3D geological models built using the software MOVE and Leapfrog Geo to characterise accurately the aquifer and set up its hydrogeological properties. The model is then exported to MODFLOW-USG with CLN using the GUI Groundwater Vistas 7. The flow model is calibrated against the measured spring discharge, with a qualitative assessment of the variations of the potentiometric surfaces. The Manning equation is used to simulate the non-laminar groundwater flow in the conduit system, while the Darcy equation is used for laminar groundwater flow in the continuum porous medium. Sensitivity analysis indicates that matrix hydraulic conductivity, specific yield, conduit drain conductance and conduit radius are important parameters in the model. The dynamics of diffuse flow in areas of the aquifer between conduits are investigated, which reveals that the most influential conduit in terms of groundwater flow through such areas can change over time depending on prevailing hydrological conditions. Overall, whilst such a modelling approach does require a good understanding a the system, large datasets and a relatively long calibration process, to achieve a satisfying performance (in the current configuration of the code and GUI and available data at the site), MODFLOW-USG with CLN proves to be a powerful tool which can be used to further understand the dynamics of the karst aquifer involved and can help inform the management of water resources both quantitatively and qualitatively.

岩溶系统由于其水文地质参数的非均质性和高度的空间变异性，在基于物理的数值模型的应用方面提出了许多挑战。一些模型可能会面临特定于岩溶环境的概念限制（例如等效的多孔介质模型）。开发并发布了新版本的MODFLOW，称为MODFLOW-USG（非结构网格）（Panday等人，2013），实现了非结构网格和有限体积数值解，以实现物理上更精确的岩溶含水层建模。在本研究中，我们首次在位于爱尔兰Leitrim县Manorhamilton春季的小爱尔兰集水区测试了带有CLN的MODFLOW –USG的能力。为了创建这个岩溶系统的数值模型，我们开发了一种方法，该方法结合了使用软件MOVE和Leapfrog Geo构建的3D地质模型，以准确表征含水层并建立其水文地质特性。然后使用GUI Groundwater Vistas 7将模型导出到带有CLN的MODFLOW-USG。根据测得的弹簧流量对流量模型进行校准，并对电位计表面的变化进行定性评估。Manning方程用于模拟管道系统中的非层状地下水流动，而Darcy方程用于模拟连续介质中的层状地下水流动。敏感性分析表明，基质的水力传导率，比产率，导管排水电导率和导管半径是模型中的重要参数。研究了导管之间含水层区域中扩散流的动力学，这表明就流经这些区域的地下水而言，最具影响力的导管可能会随时间流逝而变化，这取决于当时的水文条件。总体而言，尽管这种建模方法确实需要对系统，大型数据集和相对较长的校准过程有充分的了解，才能获得令人满意的性能（在代码和GUI的当前配置以及现场的可用数据中），但MODFLOW-事实证明，带有CLN的USG是一个功能强大的工具，可用于进一步了解所涉及的岩溶含水层的动态，并有助于定量和定性地为水资源管理提供信息。这表明就流经这些地区的地下水而言，最具影响力的管道可能会随时间流逝而变化，这取决于当时的水文条件。总体而言，尽管这种建模方法确实需要对系统，大型数据集和相对较长的校准过程有充分的了解，才能获得令人满意的性能（在代码和GUI的当前配置以及现场的可用数据中），但MODFLOW-事实证明，带有CLN的USG是一个功能强大的工具，可用于进一步了解所涉及的岩溶含水层的动态，并有助于定量和定性地为水资源管理提供信息。这表明，就流经这些地区的地下水而言，最具影响力的管道可能会随着时间的流逝而变化，这取决于当时的水文条件。总体而言，尽管这种建模方法确实需要对系统，大型数据集和相对较长的校准过程有充分的了解，才能获得令人满意的性能（在代码和GUI的当前配置以及现场的可用数据中），但MODFLOW-事实证明，带有CLN的USG是一个功能强大的工具，可用于进一步了解所涉及的岩溶含水层的动态，并有助于定量和定性地为水资源管理提供信息。