坡面流超声波水深测量系统研究

Study on Evaluating Ultrasonic Measurement System of Overland Flow Depth

坡面流水深是常用的水动力学参数,是计算坡面流流速、水流剪切力、水流功率的基础,因而对其准确测量至关重要。室内侵蚀静床实验中水深直接测量法耗时长、误差大,而间接测量法一般是通过染色法测定流速进而反推出坡面流水深,测量精度受水流流态、测流区长度和含沙量等因素影响。鉴此,对超声波距离传感器应用于侵蚀静床坡面流水深测量进行系统研究,通过参数调试和测量系统检验,表明超声波水深测量系统测量不同厚度玻璃的平均相对误差为1.73%,对不同坡度、不同流量组合下坡面流测距的变异系数在0.061%～0.096%之间,其精度能够满足室内侵蚀静床条件下坡面流水深测量的研究需求,可用于侵蚀静床条件下坡面流水动力学特性、坡面流挟沙力、输沙及模拟覆盖对坡面流水动力学特性潜在影响的研究。

Overland flow depth, which is a commonly used hydrodynamic parameter, is the basis in calculating flow velocity, flow shear stress and stream power. It is very important to be accurately measured. Direct measurement in laboratory erosive fixed bed experiments is time-consuming with big errors. Besides, indirect measurement calculates overland flow depth through measuring flow velocity by dye tracing method, however the accuracy of this kind of method is usually limited by flow regime, measurement length, sediment concentration, etc. Thus, this paper systematically studied the applicability of ultrasonic distance sensor in measuring overland flow depth of erosive fixed bed. Parameters adjusting and measurement system testing showed that the average relative error in measuring glasses with different thickness was 1. 73% and the coefficient of variation in measuring overland flow distance under different combinations of discharge and slope gradient ranges from 0. 016% to 0. 096%, which meant that the precision of this system could meet the researching needs of overland flow depth＇s measurement under the condition of laboratory erosive fixed bed experiment, and the system could be used in research with respect to hydrodynamic properties and sediment carrying capacity of overland flow, as well as the potential impact of sediment transport and simulated coverage on hydrodynamic properties of overland flow.