Wave‐supported fluid mud (WSFM) plays an important role in sediment downslope transport on the continental shelves. In this study, we incorporated WSFM processes in the wave boundary layer (WBL) into the Community Sediment Transport Modeling System (CSTMS) on the platform of the Coupled Ocean‐Atmosphere‐Wave‐and‐Sediment Transport modeling system (COAWST). The WSFM module was introduced between the bottommost water layer and top sediment layer, which accounted for the key sediment exchange processes (e.g., resuspension, vertical settling, diffusion, and horizontal advection) at the water‐WBL and WBL‐sediment bed boundaries. To test its robustness, we adapted the updated model (CSTMS + WBL) to the Atchafalaya shelf in the northern Gulf of Mexico and successfully reproduced the sediment dynamics in March 2008, when active WSFM processes were reported. Compared with original CSTMS results, including WSFM module weakened the overall intensity of sediment resuspension, and the CSTMS + WBL model simulated a lutocline between the WBL and overlying water due to the formation of WSFM. Downslope WSFM transport resulted in offshore deposition (>4 cm), which greatly changed the net erosion/deposition pattern on the inner shelf off the Chenier Plain. WSFM flux was comparable with suspended sediment flux (SSF) off the Atchafalaya Bay, and it peaked along the Chenier Plain coast where wave activities were strong and the bathymetric slope was steep. The influence of fluvial sediment supply on sediment dynamics was limited in the Atchafalaya Bay. Sensitivity tests of free settling, flocculation, and hindered settling effects suggested that sediments were transported further offshore due to reduced settling velocity in the WBL once fluid mud was formed. Although sediment concentration in the WBL was sensitive to surface sediment critical shear stress, cohesive bed behavior was less important in WSFM dynamics when compared with strong hydrodynamic during cold fronts.

中文翻译：

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阿查法拉雅大陆架冷锋前波浪支撑重力流的数值研究

波浪支撑的泥浆（WSFM）在大陆架上的沉积物下坡运输中起着重要作用。在这项研究中，我们将波边界层（WBL）中的WSFM过程整合到了海洋-大气-波-沉积-沉积耦合模拟系统（COAWST）平台上的社区沉积物传输模拟系统（CSTMS）中。在最底层水层和顶层沉积物层之间引入了WSFM模块，该模块解释了水-WBL和WBL-沉积床边界处的关键沉积物交换过程（例如，重悬浮，垂直沉降，扩散和水平对流）。为了测试其坚固性，我们将更新后的模型（CSTMS + WBL）应用于墨西哥湾北部的Atchafalaya架子，并于2008年3月成功再现了沉积物动力学，报告活动的WSFM流程时。与原始CSTMS结果相比，包括WSFM模块降低了沉积物的总体悬浮强度，CSTMS + WBL模型模拟了由于WSFM的形成而在WBL和上覆水之间形成了一条卢克线。下坡WSFM运移导致近海沉积（> 4 cm），这大大改变了Chenier平原内陆架的净侵蚀/沉积方式。WSFM通量可与Atchafalaya湾外的悬浮泥沙通量（SSF）相提并论，它沿Chenier平原海岸达到顶峰，那里的波浪活动很强，且测深斜率很陡。在阿查法拉亚湾，河流沉积物供应对沉积物动力学的影响是有限的。自由沉降，絮凝，沉降的影响表明，一旦形成泥浆，由于WBL中沉降速度的降低，沉积物将被进一步输送到近海。尽管WBL中的泥沙浓度对表面泥沙临界剪切应力敏感，但与冷锋期间的强水动力相比，WSFM动力学中的粘性床行为不那么重要。