Data from: The effects of three repeated unsteady flow hydrographs on sand bed topography and sediment transport in a laboratory flume

This is the dataset that was used to make the figures for the publication entitled "The effects of three repeated unsteady flow hydrographs on sand bed topography and sediment transport in a laboratory flume"The citation for the publication is: Wren, D. G., McAlpin, T. O., Langendoen, E. J. and Kuhnle, R. A. The effects of three repeated unsteady flow hydrographs on sand bed topography and sediment transport in a laboratory flume. Journal of Hydraulic Engineering. Accepted 10/31/2024.How the dataset was generated: Experiments were conducted at the USDA-ARS National Sedimentation Laboratory in a 30-meters long x 1.22-meters wide x 0.61-meter-deep flume channel with a frequency-controlled pump motor and adjustable slope. The sand for the bed was purchased from a local source and had a median particle size of 0.43 mm. The bed load transport rate was measured by a Sedflux system that operated at 1 Hz (Hertz, cycles per second) using two drums suspended from load cells over 1.2 meters wide by 0.57 meters long sediment trap that was 28.5 meters from the channel origin. The mass of sand accumulated in the drums was recorded continuously, and the drums were dumped after the mass of sediment reached 30 kilograms. After leaving the drums, the sand particles were circulated through a 0.152-meter diameter pipeline and re-entered the flume at the upstream end. Material that bypassed the trap entered the main return pipe and was sampled from the center of the return pipe just downstream of the pump impellor using a 10.6-millimeter diameter sampling nozzle. Flow velocity into the nozzle was matched to the mean return line flow velocity to avoid biasing the concentration measurements. Discharge in the sampling line was checked by measuring the mass of water accumulated over time. Sediment-laden water was passed through a 0.062 mm sieve that retained sand particles and allowed the water to return to the flume channel. The mean sediment concentration from the physical samples was used to calculate the load that bypassed the Sedflux system. Bed surface elevations were measured acoustically at a rate of 10 Hertz using 32 transducers with an acoustic frequency of 5-million cycles per second, fired sequentially. The transducers were spaced at 3.7-centimeter intervals in a PVC bar with a blunt face and narrow trailing edge to minimize flow separation and drag. The transducers were held at a constant distance from the bottom of the flume and were always in contact with the water surface. The range data measured in the experiments was subtracted from the measured distance to the flume bottom to result in bed elevations. The working section of the flume, which took 3.85 minutes to scan, extended from 7.7 meters to 22.7 meters from the origin at the flume headbox. Position data recorded along with the acoustic range data was used to assign streamwise positions relative to the flume origin.Why the dataset was generated: Relative to the research into sediment transport in unsteady flows for gravel and gravel/sand mixtures, less research has focused on sand-bedded channels and the evolution of sand bedforms in response to changing flows. Even less research has combined sand load with detailed topographic measurements to arrive at a comprehensive picture of the adjustment processes for topography and transport rate caused by unsteady flow conditions. Additional research is needed to provide the data necessary for investigating relationships between unsteady flow rates, sediment transport, and bed topography. The dataset expands on previous research into sediment transport and bed topography in unsteady flows by having detailed, real-time measurements of bed topography over the width of a 15-m section of a laboratory flume, continuous measurements of sediment transport rate throughout the experiments, and continuous measurements of water-surface slope at 10 points along the test section. These measurements allowed for interactions between changing flow rates, bed topography, water surface slope, and sediment transport to be evaluated before, during, and after the flow hydrographs. The results include detailed analysis of data collected during non-symmetric flow of three repeated hydrographs of 1-, 2-, 3-, 4-, 5-, and 6-hour duration over a sand bed in a laboratory flume at the USDA-ARS National Sedimentation Laboratory.Data resources: Each file contains the data used to generate the figure corresponding to the figure number in the filename for the publication referenced at the beginning of this description.Figure_1.csvFigure_3.csvFigure_4.csvFigure_5.csvFigure _6.csvFigure_7.csvFigure_8.csvFigure_9.csvFigure_10A.csvFigure_10B.csvFigure_11.csvFigure_12.csvFigure_13.csvFigure_14.csv

本数据集系为制作《三种重复不稳定流水力图谱对实验室水槽中沙床地形及泥沙运移的影响》一文中插图而使用。该文献的引用信息如下：Wren, D. G., McAlpin, T. O., Langendoen, E. J. 和 Kuhnle, R. A. 三种重复不稳定流水力图谱对实验室水槽中沙床地形及泥沙运移的影响。水工学报。接受于2024年10月31日。
数据集生成方式：实验于美国农业部农业研究服务局国家泥沙实验室的30米长、1.22米宽、0.61米深的流槽中进行，流槽配备了频率控制的泵电机和可调节的坡度。流槽底部的沙子来自当地来源，其平均粒径为0.43毫米。床面运移速率通过Sedflux系统进行测量，该系统以1赫兹（赫兹，每秒循环次数）的频率运行，使用两个悬挂在负载传感器上的、宽1.2米、长0.57米的泥沙收集器，该收集器位于距离流槽起点28.5米处。收集器中累积的沙子质量被连续记录，并在沙子质量达到30公斤后清空。沙粒在离开收集器后，通过直径为0.152米的管道循环，并重新进入上游端的水槽。绕过收集器的材料进入主回流管，并在泵叶轮下游侧的回流管中心位置使用直径为10.6毫米的采样喷嘴进行采样。喷嘴中的流速与平均回流线流速相匹配，以避免对浓度测量造成偏差。采样线的排放量通过测量随时间累积的水的质量进行检查。含沙水通过直径为0.062毫米的筛网，该筛网保留沙粒，并允许水返回流槽通道。从物理样品中得到的平均泥沙浓度被用于计算绕过Sedflux系统的负荷。床面高程通过声学方式以每秒10赫兹的频率进行测量，使用32个频率为每秒500万次的传感器依次发射。传感器以3.7厘米的间隔设置在具有钝面和窄后缘的PVC杆上，以最小化流动分离和阻力。传感器保持与流槽底部的恒定距离，并且始终与水面接触。实验测量的范围数据从测量的流槽底部距离中减去，得到床面高程。流槽的工作区域，耗时3.85分钟扫描，从流槽头箱起点的7.7米延伸至22.7米。与声学范围数据一同记录的位置数据被用于确定相对于流槽起点的顺流位置。
数据集生成原因：与对砾石和砾石/沙混合物在非稳定流中的泥沙运移研究相比，针对沙床渠道以及沙床形态随水流变化而演化的研究相对较少。更少的研究将沙负荷与详细的拓扑测量相结合，以形成一个关于由非稳定流条件引起的地形和运移速率调整过程的综合图景。有必要进行额外的研究，以提供调查非稳定流速、泥沙运移和床面地形之间关系所需的数据。该数据集通过在实验室水槽15米宽的沙床区域进行详细的实时地形测量，在整个实验过程中对泥沙运移速率的连续测量，以及对测试段沿线的10个点的水面坡度的连续测量，扩展了先前对非稳定流中泥沙运移和床面地形的研究。这些测量允许在流量速率、床面地形、水面坡度和泥沙运移变化之前、期间和之后评估它们之间的相互作用。结果包括对在USDA-ARS国家泥沙实验室的实验室水槽中对三种重复水力图谱（持续时间为1小时、2小时、3小时、4小时、5小时和6小时）的沙床进行非对称流实验期间收集到的数据的详细分析。
数据资源：每个文件包含用于生成与文件名中图号相对应的图示的数据。