This study examines the occurrence of riparian lenses adjacent to partially penetrating, gaining rivers under the controlled conditions of a laboratory sand tank. Laboratory experiments and numerical modeling of the freshwater lens extent are used to provide physical verification (in light of limited examples of well-characterized field cases) of the analytical methodology, thereby evaluating the underlying assumptions. Parameter calibration and uncertainty analysis are applied to assess both the experimental conditions and the benefit of lens observations in applying the analytical approach. The experimental freshwater lens was reproduced by both analytical and numerical models, with the exception of small mismatches (between analytical results and measured data) in the lens thickness in the near-river region. These are most likely due to vertical flow effects that arise from the partial river penetration and saltwater inflows to the river bottom, and that are only partly accounted for in the analytical approach. Uncertainty analysis highlighted that accurate lens predictions based on the analytical method requires calibration to direct lens measurements; a similar finding from earlier studies of fully penetrating river conditions. Sensitivity analysis highlighted that the saltwater head boundary, freshwater and saltwater densities, and the aquifer depth below the riverbed (in descending order of sensitivity) are the most important factors in controlling freshwater lens occurrence and saltwater discharge. The results provide the first physical verification of the occurrence of stable riparian lenses adjacent to partially penetrating, gaining rivers, and verify a recent analytical solution for lens extent and saltwater discharge.

中文翻译：

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河流部分渗透对河岸淡水透镜体发生的影响：实验研究

这项研究检查了在实验室沙箱的受控条件下，与部分渗透、获得河流相邻的河岸透镜体的出现。淡水透镜体范围的实验室实验和数值建模用于提供分析方法的物理验证（根据充分表征的现场案例的有限示例），从而评估基本假设。应用参数校准和不确定性分析来评估实验条件和镜头观察在应用分析方法时的好处。实验性淡水透镜体由分析和数值模型复制，除了近河区域透镜体厚度的小不匹配（分析结果和测量数据之间）。这些很可能是由于部分河流渗透和盐水流入河底引起的垂直流动效应，而这在分析方法中仅部分考虑。不确定性分析强调，基于分析方法的准确镜头预测需要校准以指导镜头测量；早期对完全渗透的河流条件的研究也有类似的发现。敏感性分析强调，咸水水头边界、淡水和咸水密度以及河床以下含水层深度（按敏感度降序排列）是控制淡水透镜体发生和咸水排放的最重要因素。结果提供了第一次物理验证，证实了与部分穿透、获得河流、