The sediment transport direction is affected by the bed slope. This effect is of crucial importance for two- and three-dimensional modelling of the interaction between the flow of water and the alluvial bed. It is not uncommon to find applications of numerical morphodynamic models in the literature that exaggerate the effects of transverse bed slopes on sediment transport compared to results from laboratory experiments. We investigate mathematically the consequences of such an approach, and we analyse through numerical simulations different explanations for the need to apply deviating values. The study reveals that the reason often lies in the setup of the numerical models, such as the choice of mesh resolution or the necessity to comply with specific aspects of the numerical scheme. The missing or inadequate implementation of physical processes in the model is another cause. All of these effects can be compensated by artificial diffusion added through the bed slope effect coefficients. Since increased diffusion strongly alters the physical processes of self-formed bed morphology, we recommend that modellers address the root causes of inflated erosion and deposition. Bed slope effect coefficients should be applied within the range found in the original publications.

中文翻译：

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为什么已发布的河流和河口形态动力学模型使用不切实际的河床斜坡影响表示？


沉积物输送方向受河床坡度的影响。这种效应对于水流和冲积层之间相互作用的二维和三维建模至关重要。与实验室实验结果相比，在文献中发现数值形态动力学模型的应用并不少见，这些模型夸大了横向河床斜坡对沉积物输送的影响。我们从数学上研究了这种方法的后果，并通过数值模拟分析了对应用偏差值需要的不同解释。研究表明，原因通常在于数值模型的设置，例如网格分辨率的选择或符合数值方案的特定方面的必要性。模型中物理过程的缺失或不充分实现是另一个原因。所有这些影响都可以通过通过床坡效应系数添加的人为扩散来补偿。由于扩散增加会强烈改变自形成床形态的物理过程，因此我们建议建模人员解决膨胀侵蚀和沉积的根本原因。床坡度效应系数应在原始出版物中找到的范围内应用。