Transport processes that lead to exchange of mass between surface water and groundwater play a significant role for the ecological functioning of aquatic systems, for hydrological processes and for biogeochemical transformations. In this study, we present a novel integral modeling approach for flow and transport at the sediment–water interface. The model allows us to simultaneously simulate turbulent surface and subsurface flow and transport with the same conceptual approach. For this purpose, a conservative transport equation was implemented to an existing approach that uses an extended version of the Navier–Stokes equations. Based on previous flume studies which investigated the spreading of a dye tracer under neutral, losing and gaining flow conditions the new solver is validated. Tracer distributions of the experiments are in close agreement with the simulations. The simulated flow paths are significantly affected by in- and outflowing groundwater flow. The highest velocities within the sediment are found for losing condition, which leads to shorter residence times compared to neutral and gaining conditions. The largest extent of the hyporheic exchange flow is observed under neutral condition. The new solver can be used for further examinations of cases that are not suitable for the conventional coupled models, for example, if Reynolds numbers are larger than 10. Moreover, results gained with the integral solver provide high-resolution information on pressure and velocity distributions at the rippled streambed, which can be used to improve flow predictions. This includes the extent of hyporheic exchange under varying ambient groundwater flow conditions.

中文翻译：

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用于研究地表水-地下水相互作用的高分辨率综合传输模型

导致地表水和地下水之间质量交换的传输过程对水生系统的生态功能、水文过程和生物地球化学转化起着重要作用。在这项研究中，我们提出了一种新的用于沉积物 - 水界面处的流动和运输的整体建模方法。该模型允许我们使用相同的概念方法同时模拟湍流表面和地下流动和传输。为此，对现有方法实施了保守的输运方程，该方法使用 Navier-Stokes 方程的扩展版本。基于之前的水槽研究，该研究调查了染料示踪剂在中性、失去和获得流动条件下的扩散，新的求解器得到了验证。实验的示踪剂分布与模拟非常一致。模拟的流动路径受到流入和流出地下水流的显着影响。沉积物中的最高速度被发现用于失去条件，与中性和获得条件相比，这导致更短的停留时间。在中性条件下观察到最大程度的低流交换流。新的求解器可用于进一步检查不适用于传统耦合模型的情况，例如雷诺数大于 10 的情况。此外，积分求解器获得的结果可提供有关压力和速度分布的高分辨率信息在波纹河床，可用于改进流量预测。