Streamlab 2006

StreamLab06 was a multiphase research endeavor involving academic researchers, federal agencies and stream restoration practitioners. This ongoing project is being conducted in the Main Channel at the St. Anthony Falls Laboratory in Minneapolis, MN. The StreamLab program brings together a spectrum of research expertise (stream ecology and biology, engineering, hydrology, hydraulics and geomorphology) to conduct focused studies on a laboratory controlled, field scale, indoor stream environment. The first phase of the StreamLab06 project was completed in late March, 2006, and was focused on testing several existing and one new technology for sampling bedload transport. Technologies were tested in separate sets of sand and gravel trials. For the former, the channel was pre-loaded with sediment consisting of nearly uniformly sized (approximately 0.8mm) sand. Transported sand was captured in the channel's weigh pans, weighed, and recirculated. The water discharge varied (from trial to trial) between 2.0 and 3.6 cubic feet per second. Three standard "manual" samplers were tested: a 3" Helley-Smith, a 3" BL84 and an Elwha Sampler. For each, samples were taken at a fixed lateral position in the flow, just upstream from the weigh pans. Samples were taken over times varying from 15 seconds to one minute to see what sample-time would be necessary to capture natural variability in the sediment transport. In addition to these samplers, two (1200 and 600 kHz) Acoustic Doppler Current Profilers (ADCP) were installed and tested. These units just touch the water surface, and have the potential to deliver non-destructive information on sediment transport. For this experiment, researchers concentrated on the zones just upstream and downstream of the unit. In the downstream zone, which was just upstream of the weigh pans, a velocimeter (16mHz Micro ADV) provided a velocity profile of the flow, which will be used to calculate bed stresses. Finally, a 100 frame-per-second digital video camera capable of resolving individual grains captured the flow as it passed through the downstream zone. For the second set of trials, the sand was cleared from the channel, replaced with gravel, and several runs with varying discharges (up to a maximum of 5.5 cubic meters per second) were conducted. The same bedload sampling technologies were in place for the gravel runs, and a Toutle River 2 sampler was added to the mix.StreamLab06是一项多阶段研究项目，汇聚了学术研究者、联邦机构工作人员以及河流修复从业者。该项目目前正在明尼苏达州明尼阿波利斯市圣安东尼瀑布实验室的主河道内持续开展。StreamLab项目整合了多领域研究专长（河流生态学与生物学、工程学、水文学、水力学及地貌学），旨在对实验室可控的野外尺度室内河道环境开展针对性研究。 StreamLab06项目的第一阶段已于2006年3月下旬完成，核心目标是测试多款现有技术及一项新技术的推移质采样性能，相关测试分为沙质与砾石两组试验开展。 针对沙质试验组，河道预先装填了粒径近乎均匀（约0.8毫米）的砂质沉积物。被推移的砂粒将通过河道内的称重托盘收集、称重后再循环回用。各试验的水流量介于2.0至3.6立方英尺每秒之间，随试验不同有所调整。 本次测试了三款标准‘手动’采样器：3英寸Helley-Smith采样器、3英寸BL84采样器以及Elwha采样器。每款采样器均设置在称重托盘上游的固定横向流场位置进行采样。采样时长设置为15秒至1分钟不等，以探究捕捉沉积物输运自然变异性所需的最优采样时长。 除上述采样器外，本次还安装并测试了两台（1200kHz与600kHz）声学多普勒流速剖面仪（Acoustic Doppler Current Profilers，ADCP）。该类设备仅需接触水面即可获取沉积物输运的非侵入式监测数据。本次试验中，研究人员重点关注了设备上下游的流场区域。 在紧邻称重托盘上游的下游流场区域内，研究人员部署了一台测速仪（16mHz Micro ADV）以获取流场流速剖面，该剖面将用于计算床面应力。最终，一台可分辨单个颗粒的100帧每秒高速数码摄像机记录了流场经过该下游区域的全过程。 针对第二组砾石试验，研究人员先清空河道内的砂质沉积物，更换为砾石，并开展了多组流量可变的试验，最大流量可达5.5立方米每秒。砾石试验沿用了沙质试验的推移质采样技术，同时新增了Toutle River 2采样器。