Improved TDR Suspended Sediment Concentration Measurement By Frequency Domain Phase Velocity Method

• Main Authors: Chang,Chih-Tung, 張智棟
• Other Authors: Lin, Chih-Ping
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/42843374297560764977

碩士 === 國立交通大學 === 土木工程系所 === 98 === Due to the complex geology and rapid weathering changes in Taiwan, suspended sediment concentration (SSC) measurement is important for sediment discharge and desilting operation in reservoirs during heavy rainfalls.. Time domain reflectometry method (TDR) has been developed recently for SSC monitoring with advantages of economy, maintainability, high SSC monitoring, and relative independence of water salinity and particle size. According to the previous study, TDR SSC measurement accuracy has been improved to 1500 ppm. However, the algorithm for estimating SSC of the existing TDR SSC method utilizes time domain analysis, thus the in-situ SSC monitoring results are often interfered by electronic and environmental noise. To avoid the effect of noise in the time domain analysis, a new frequency domain algorithm called the Frequency Domain Phase Velocity (FDPV) method was recently proposed.. But the proof of concept for the FDPV method was only performed with numerical simulations without experimental verification. Consequently, the objective of this study was to implement the Frequency Domain Phase Velocity (FDPV) method and experimentally investigate its performance for TDR SSC measurement. Experimental results show that SSC measurement based on the FDPV method is relatively independent of water salinity, cable resistance, and sediment type. Furthermore, this research developed a new TDR SSC coaxial probe, to go along with the FDPV method which provides higher measurement stability in-situ. The applicability of the FDPV method and new coaxial probe was also verified by field testing. However, some measurement variation with air temperature was revealed in the field testing. The temperature effect was attributed to temperature dependency of the sampling interval in the TDR device. Further study is suggested to investigate the temperature effect and compensation method.