In steady uniform boundary layers, the dynamics of sediment resuspension and transport are controlled by near-bed turbulence, often quantified by bed shear stress, τb. Over the past few decades, various methods have been developed to infer bed shear stress using noninvasive, high-resolution flow observations from acoustic instruments. However, there is room for improvement in these methods. This study adopts an inertial dissipation method for sediment (IDM_Sed) to improve the accuracy of shear stress estimation from suspended sediment concentrations (SSC) and to evaluate IDM_Sed performance in cohesive sediment environments by incorporating more accurate, time- and elevation-varying settling velocities. Comprehensive observations were conducted on the Songdo tidal flats over more than one month in 2023, using both acoustic and optical instruments. Our results suggest that the improved IDM_Sed enhances the accuracy of computed shear stress. In cohesive environments, this method captures trends in shear stress induced by current velocity and incorporates influences from sediment concentration. Moreover, the enhancement of shear stress calculation in IDM_Sed, incorporating SSC and in-situ observed shear velocities, proposes a novel method to compute time-varying settling velocities from shear stress.

中文翻译：

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前沿 |粘性沉积物环境下悬浮沉积物浓度的床层剪切应力和沉降速度估计


在稳定均匀的边界层中，沉积物再悬浮和输运的动力学由近床湍流控制，通常由床层剪切应力 τb 量化。在过去的几十年里，已经开发了各种方法，使用声学仪器的非侵入性、高分辨率流动观测来推断床层剪切应力。但是，这些方法仍有改进的余地。本研究采用沉积物惯性耗散法 （IDM_Sed） 来提高悬浮沉积物浓度 （SSC） 剪切应力估计的准确性，并通过引入更精确的、随时间和海拔变化的沉降速度来评估IDM_Sed在粘性沉积物环境中的性能。2023 年，使用声学和光学仪器对松岛滩涂进行了为期一个多月的全面观测。我们的结果表明，改进的IDM_Sed提高了计算剪应力的准确性。在粘性环境中，该方法捕获了由电流速度引起的剪切应力的趋势，并结合了沉积物浓度的影响。此外，IDM_Sed 中剪切应力计算的增强，结合了 SSC 和原位观测的剪切速度，提出了一种根据剪切应力计算时变沉降速度的新方法。