Practical Assessment of Real-Time Suspended Sediment Load Monitoring Using Time Domain Reflectometry

Suspended sediment concentration (SSC) and sediment load are essential factors in water resource management, hydraulic engineering, soil and water conservation, sedimentation, and environmental ecology. A novel real-time SSC monitoring approach involving time domain reflectometry (TDR) was proposed. The previous results obtained indicated that the soil particle size does not affect the TDR SSC method and that this method is applicable at high suspended sediment concentrations (≥600,000 ppm). To further improve the measurement stability and accuracy of this method for long-term monitoring of rivers and reservoirs, several practical problems were solved in this study, including noise interference, probe fouling, and the effect of ambient temperature on the TDR device used. With the proposed improvements in the analysis of the modified frequency domain phase velocity, the new method was examined in a laboratory setting, and a measurement standard deviation of 1,000 ppm was found. In addition, a novel carbon fiber rod with a novel detachable probe was proposed to decrease the nonlinear SSC variations resulting from the coating effect as part of the electromagnetic sensing field. As observed during the experiment, the use of a fully digital TDR device decreased the ambient temperature effect. Several TDR SSC measurements were performed at the Shihgang Reservoir, revealing long-term SSC and sediment load typhoon events from 2013 to 2021. Subsequently, real-time TDR SSC monitoring with sediment load quantification was performed to establish the relationship between sediment load and outflow discharge, and the results obtained indicated that this method helped characterize suspended sediment load.