坡面径流实时监测装置的测试与率定

径流小区观测技术是水土保持监测评价的基础.研发适用于径流小区尺度的径流观测装备可有效减少人工监测的随机性,降低监测人员的工作强度.通过人工模拟不同强度的产流汇水条件,对“径流泥沙含量实时测量装置”开展径流测量性能的专项测试,结果表明:该装置在测试环境条件下的径流测量相对误差范围为-4.33％～-24.01％,稳定时长范围为55 ～ 130 s.偏相关分析发现:测量稳定时长与径流的含沙量、流量分别呈显著正相关关系和显著负相关关系(P＜0.05);测量精度与含沙量和流量的相关系数均呈负相关关系,但含沙量和流量对测量精度的影响有限(α=0.05).通过回归分析,得到该装置径流量修正模型;经验证,该模型可使平均相对误差由修正前的11.53％降低至6.80％,平均测量数据稳定时间由修正前的96 s降低至80 s.研究分析提出,通过对上述设备增设波浪过滤消减装置、增大滤波管直径等措施可进一步降低测量误差,提高工作稳定性.基于上述测试结果,本研究认为通过利用修正模型,测试设备的径流测量效果在测试流量范围内较为理想,即该设备在降雨强度范围为3.60 ～ 66.96 mm/h的产流工作条件下较为适宜.

Test and calibration of a real-time hillslope runoff measuring device

Background]Water and soil loss has been a major environmental issue,and people's demands on environment quality are raised constantly in China.In this context,a nationwide water and soil loss monitoring network was set up,the count of water and soil loss monitoring stations increased to 738 recently.Although network built quickly,but the dedicated devices used in water and soil loss monitoring still fall behind very much.For example,manual throughfall collecting tank was invented centuries ago,but it's still used widely now in China.Therefore,developing and testing automated dedicated devices used in water and soil loss monitoring is an urgent and long-term task,which can enhance people's ability of monitoring and controlling water and soil loss.Automatic hillslope runoff measuring device is a gauge that can be used in a scale of runoff plot to replace human beings to measure,which can enhance the monitoring efficiency greatly.Methods] This paper took the measurement accuracy of a Runoff & Sediment Real-time Measuring Device as research object,the relative errors between theoretical value and measurement value were calculated based on the artificial runoff-producing simulation.Analysis of partial correlation was used to uncover the cause of error.With regression analysis,a fitted relationship between the runoff true value and the measured value was established.Results] The results showed that the range of the relative error of runoff was-4.33％-24.01％,and the range of the stabilization time was 55-130 s.Based on the analysis of partial correlation,the stabilization time for measured values had a significantly positive correlation with sediment concentration,and had a significant inverse correlation with design flow (P ＜ 0.05).The accuracy of measurement had a significantly positive correlation with sediment concentration and design flow,but both sediment concentration and design flow presented limited influences on accuracy of measurement(α =0.05).Regress equation between the measurement of runoff and revised values was found by using the regression analysis.It was proved that accuracy of the measurement and the stabilization time for runoff measurements was significantly improved.Furthermore,the research also demonstrates that increasing waves cutting device and enlarging the size of waves filter can be conducive to improve accuracy of the measurement.Conclusions] These results were beneficial to understand the measuring performance of device in this study.With the rainfall intensity range 3.60 mm/h-66.96 mm/h,runoff can be measured accurately by the device,the range of rainfall intensity mentioned above can represent different rain types,such as moderate rain,heavy rain and rainstorm in northern China.For improving measurement accuracy in the future,the impact of silt content and mechanical composition should be considered and explored.