Technical Studies

The rivers and creeks in Taiwan have characteristics of small basin, high flow velocity, and rapid change between base flow and storm flow, most transportation of suspended sediment occurs in a few torrential rain incidents. While suspended-sediment concentration (SSC) can be observed by manual sampling and lab testing, but it is difficult to predict the right sampling timing and mobilize field crew during storms. The SSC in river has high spatial and temporal variability, but durable, efficient and automated techniques for high SSC monitoring are yet to be discovered. To overcome the aforementioned problems, a new method based on time domain reflectometry (TDR) was proposed and pilot SSC automatic monitoring stations were established to evaluate TDR performance and compare with other commercial instruments. Compared with traditional labor sampling, TDR SSC method has advantages on real-time automation monitoring and low-cost. Unlike optical and acoustic method, TDR SSC method is less affected by the soil particle size or type, and the water salinity, and it is more economical, easy to be maintained, and applicable for high SSC monitoring.

Water Resources Agency, Ministry of Economic Affairs supported the improvement of TDR SSC method in 2008, and a new coaxial type probe and an innovative analytical algorithm for SSC measurement are developed to increase the measurement accuracy. Due to the lacks of in-situ verifications, this study supposes to focus on collecting more date, and provides the standard operation processes of station establishment, equipment setup, measurement procedures, data processing, and maintains at the end of this project.