小流域土壤侵蚀及径流过程自动测量系统的实验应用

Laboratory applications of an automated measuring system for soil erosion and runoff processes in small watershed

流域内降雨-径流-土壤侵蚀过程中不同时空点处流量、流速、泥沙含量的获取是土壤侵蚀机理研究中的难点,其实时、准确测量为侵蚀模拟-预报模型的建立与检验提供必要的数据支持。该文针对这一问题,将量水堰及水位传感器、薄层水流流速测量系统、γ射线泥沙含量测量仪有机组合,构成流域土壤侵蚀过程测量系统。将该系统测量仪器布设于室内小流域模型各沟道出口及沟道内典型点处,在降雨强度25 mm/h,降雨历时5 m in条件下,系统测量的流域出口处流量及泥沙含量变化值与采用手工采样方法测量结果的决定系数R2分别为0.738,0.749,流速误差为8.7%,比较结果显示该系统具有较高的测量精度。在此测量精度范围内,同时测得各沟道口流量及泥沙含量动态变化过程及沟道中典型点处流速。流域内径流过程及径流含沙量的动态测量结果表明将该系统应用到土壤侵蚀动态过程的研究中是可行的。

Different temporal and spatial runoff rate, flow velocity and sediment yield in watersheds during the rainfall-runoff-soil erosion processes are of great importance for understanding the soil erosion mechanism. Their onsites and accurate measurements will provide theory data for physically based soil erosion simulation/prediction models. An automated system was presented in this paper for the measurements of the factors affecting soil erosion dynamic processes. The whole measurement system consists of weir and water level sensor systems, shallow water flow velocity measuring systems, sediment concentration measuring systems. The measuring system was set at every channel outlet and the typical points in the channels to obtain erosion dynamic processing in a laboratory watershed model. During 25 mm/h and 5 min rainfall period, the square correlative coefficients compared data logged by the system with the manually-measured ones to runoff and sediment concentration at the watershed outlet are 0. 738 and 0. 749, respectively, the flow velocity error is 8.7%. The results show that this system has higher feasibility and the accuracy. In the scope of accuracy, the data of runoff or sediment concentration at channels outlet were obtained, and flow velocities at typical points in channels were measured too. The measured results of runoff and sediment concentration in watershed indicate that the system is promising to be applicable in the study of soil erosion dynamic processes.