Streamlined isokinetic sediment sensor for studies of suspended sediment flux in large rivers

我们要求为流线型激光原位沉积物透射仪(LISST-SL)提供资金，用于观测大型沙床河流中的悬浮泥沙。LISST-SL同时测量水柱中某一点的水流速度、悬浮泥沙浓度和粒度分布，结合这些测量结果，可以对大范围泥沙尺寸的悬浮泥沙通量进行现场测量。申请者合作研究穿过地球表面的沙床河流的动态，这在很大程度上受每年洪水来袭时悬浮泥沙的输送控制。我们目前的研究集中在了解悬浮泥沙在大江大河中的运动，作为冲刷负荷(持续悬浮中的泥沙和粘土)和底质负荷(间歇悬浮中的沙子)。大部分工作是在弗雷泽河下游进行的，我们的发现对港口管理具有重要的实际意义。这项工作需要坚固的设备，能够承受通常超过3米/S的水流压力。我们目前的仪器没有简化，因此部署昂贵(一艘大船每天仅500美元)，精确定位是不可能的，而且采样不是等速的(测量结果不能可靠地计算沉积物通量)。LISST-SL将为我们的研究小组提供对强流和深流中流向速度、悬浮泥沙浓度和颗粒尺寸的等速测量，这些都是我们研究计划的基础。它还将使我们能够与加拿大水勘探局合作，校准使用声学多普勒海流剖面仪对悬浮沉积物进行常规传感的全新方法。

We request funding for a streamlined laser in-situ sediment transmissometer (LISST-SL) for observations of suspended sediment in large, sand-bedded rivers. The LISST-SL simultaneously measures streamwise fluid velocity, suspended sediment concentration and grain size distribution at a point in the water column, which combine to yield in-situ measurements of suspended sediment flux for a large range of sediment sizes. The applicants collaborate to examine the dynamics of sand-bedded rivers across Earth's surface, which is largely controlled by the transport of suspended sediment in response to annual flood flows. Our current research is focused on understanding the movement of suspended sediment through large rivers as wash load (silt and clay in persistent suspension) and bed-material load (sand in intermittent suspension). Most of this work is conducted in the lower Fraser River, where our findings have important practical implications for port management. This work requires robust equipment capable of withstanding stresses in flows that routinely exceed 3 m/s. Our current instruments are not streamlined so deployment is expensive ($500/day alone for a large vessel), precise positioning is impossible, and sampling is not isokinetic (measurements are not reliable for calculating sediment flux). The LISST-SL will provide our research group with the isokinetic measurements of streamwise velocity, suspended sediment concentration and particle size in strong and deep flows that are fundamental to our research programs. It will also enable us to collaborate with the Water Survey of Canada on the calibration of radically new methods for routine sensing of suspended sediment using acoustic Doppler current profilers.