This numerical modeling study (i) assesses the influence of the sediment erosion process on the sediment dynamics and subsequent morphological changes of a mixed-sediment environment, the macrotidal Seine estuary, when non-cohesive particles are dominant within bed mixtures (non-cohesive regime), and (ii) investigates respective contributions of bedload and suspended load in these dynamics. A three dimensional (3D) process-based morphodynamic model was set up and run under realistic forcings (including tide, waves, wind, and river discharge) during a 1-year period. Applying erosion homogeneously to bed sediment in the non-cohesive regime, i.e., average erosion parameters in the erosion law (especially the erodibility parameter, E₀), leads to higher resuspension of fine sediment due to the presence of coarser fractions within mixtures, compared to the case of an independent treatment of erosion for each sediment class. This results in more pronounced horizontal sediment flux (two-fold increase for sand, +30% for mud) and erosion/deposition patterns (up to a two-fold increase in erosion over shoals, generally associated with some coarsening of bed sediment). Compared to observed bathymetric changes, more relevant erosion/deposition patterns are derived from the model when independent resuspension fluxes are considered in the non-cohesive regime. These results suggest that this kind of approach may be more relevant when local grain-size distributions become heterogeneous and multimodal for non-cohesive particles. Bedload transport appears to be a non-dominant but significant contributor to the sediment dynamics of the Seine Estuary mouth. The residual bedload flux represents, on average, between 17 and 38% of the suspended sand flux, its contribution generally increasing when bed sediment becomes coarser (can become dominant at specific locations). The average orientation of residual fluxes and erosion/deposition patterns caused by bedload generally follow those resulting from suspended sediment dynamics. Sediment mass budgets cumulated over the simulated year reveal a relative contribution of bedload to total mass budgets around 25% over large erosion areas of shoals, which can even become higher in sedimentation zones. However, bedload-induced dynamics can locally differ from the dynamics related to suspended load, resulting in specific residual transport, erosion/deposition patterns, and changes in seabed nature.

该数值模拟研究 (i) 评估了沉积物侵蚀过程对混合沉积物环境（大潮塞纳河口）的沉积物动力学和随后的形态变化的影响，此时非粘性颗粒在床混合物中占主导地位（非粘性状态） )，以及 (ii) 研究床载和悬吊在这些动力学中的各自贡献。建立了一个基于三维 (3D) 过程的形态动力学模型，并在 1 年期间在真实的强迫（包括潮汐、波浪、风和河流流量）下运行。将侵蚀均匀应用于非粘性状态下的床层沉积物，即侵蚀规律中的平均侵蚀参数（尤其是可蚀性参数，E ₀)，与对每个沉积物类别的侵蚀进行独立处理的情况相比，由于混合物中存在较粗的部分，导致细粒沉积物的更高再悬浮。这会导致更显着的水平沉积物通量（沙子增加两倍，泥浆增加 30%）和侵蚀/沉积模式（浅滩上的侵蚀增加两倍，通常与床沉积物的一些粗化有关）。与观察到的测深变化相比，当在非粘性状态下考虑独立的再悬浮通量时，更多相关的侵蚀/沉积模式是从模型中得出的。这些结果表明，当非粘性颗粒的局部粒度分布变得不均匀和多峰时，这种方法可能更相关。底泥运输似乎是塞纳河口沉积物动力学的非主要但重要贡献者。平均而言，残余床荷载通量占悬浮砂通量的 17% 至 38%，当床沉积物变粗时（在特定位置可能成为主导），其贡献通常会增加。由床荷载引起的残余通量和侵蚀/沉积模式的平均方向通常遵循悬浮沉积动力学产生的那些。模拟年份累积的沉积物质量预算显示，在大面积的浅滩侵蚀区，床载对总质量预算的相对贡献约为 25%，在沉积区甚至可能更高。然而，床载引起的动力学可能与悬浮荷载相关的动力学存在局部差异，