Abstract Geological heterogeneity is a key factor affecting rates and patterns of groundwater flow and the evolution of salinity distributions in coastal aquifers. The hydrogeologic systems of volcanic aquifers are characterized by lava flows that can form connected geologic structures in the subsurface. Surface-based geostatistical techniques were adopted to generate geologically-realistic, statistically equivalent model realizations of a hydrogeologic system based on that of the Big Island of Hawaii (conduit models). The density-dependent groundwater flow and solute transport code SEAWAT was used to perform 3D simulations to investigate subsurface flow and salt transport through these random realizations. Statistically equivalent geological systems generated with sequential indicator simulation (SIS) and equivalent homogeneous systems were also simulated for comparison. Simulation results show that conduit realizations tend to have more complex salinity distributions with larger mixing zones for which the center of mass is farther offshore compared to homogeneous and SIS realizations. The zone of groundwater discharge is also farther offshore than for homogeneous and SIS models, with higher point fluxes of both fresh and saline water and greater spatial variability. This highlights the importance of the geometry of geologic features in coastal groundwater flow and solute transport processes in highly heterogeneous aquifers. It also points to the importance of preferential flow, with implications for both coastal groundwater resource management and solute fluxes to the ocean.

中文翻译：

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连接非均质性对沿海火山含水层地下水流和盐度分布的影响

摘要 地质异质性是影响地下水流动速率和模式以及沿海含水层盐度分布演变的关键因素。火山含水层的水文地质系统的特点是熔岩流，可以在地下形成连接的地质结构。采用基于地表的地质统计技术来生成基于夏威夷大岛（管道模型）的水文地质系统的地质现实、统计等效模型实现。密度相关的地下水流和溶质运移代码 SEAWAT 用于执行 3D 模拟，以通过这些随机实现来研究地下流和盐分运移。还模拟了使用顺序指标模拟 (SIS) 和等效均质系统生成的统计等效地质系统以进行比较。模拟结果表明，与均质和 SIS 实现相比，管道实现往往具有更复杂的盐度分布和更大的混合区，其中质心离岸更远。地下水排放区也比均质模型和 SIS 模型离岸更远，淡水和咸水的点通量更高，空间变异性更大。这突出了地质特征几何形状在高度异质含水层中沿海地下水流动和溶质运输过程中的重要性。它还指出了优惠流量的重要性，