A new portable in situ flume (PISF) for measuring critical bed shear stress (CBSS) was developed in this study. The PISF consists of an open bottom sediment erosion chamber and an electrically-driven pump. Unlike most existing in situ flumes with similar designs, the new PISF does not rely on monitoring the flow conditions or particle density in the sediment erosion chamber; instead, it is a pre-calibrated flume. The calibration was performed by first determining CBSS of various selected sediment samples of known particle size and density (using the law of the wall), based on flow velocity-depth profiles measured in a 6 m straight open-channel flume using a Particle Image Velocimetry (PIV) system. These same particles of known CBSS were then used in the new in-situ flume under controlled lab conditions to obtain a series of calibration curves of CBSS vs. pump electrical power. A wide variety of particle types and sizes (simulated sediments) were used in this two-step calibration procedure to widen CBSS measurement range and simulate cohesive force effects. The size of the PISF is much smaller and more practical than other similar devices as lamellar flow conditions are not required and it can be applied to a wide range of sediment types including cohesive sediments.

在这项研究中开发了一种新的便携式原位水槽（PISF），用于测量临界床层剪切应力（CBSS）。PISF由一个开放式底部沉积物侵蚀室和一个电动泵组成。与大多数现有的类似设计的现场水槽不同，新的PISF不依赖于监测沉积物侵蚀室内的流动条件或颗粒密度；而是预校准的水槽。首先通过使用颗粒图像测速仪在6 m直明槽水道中测得的流速-深度剖面，首先确定各种选定的已知粒度和密度的沉积物样品的CBSS（使用壁定律），从而进行校准（PIV）系统。然后将这些已知CBSS的相同颗粒用于新的原位在受控的实验室条件下对水槽进行测试，以获得CBSS与泵电功率的一系列校准曲线。在此两步校准过程中，使用了各种类型和尺寸的颗粒（模拟的沉积物）来扩大CBSS的测量范围并模拟内聚力效应。PISF的尺寸比其他类似装置小得多，并且更实用，因为不需要层流条件，并且它可以应用于各种类型的沉积物，包括粘性沉积物。