标题: 河川含砂浓度全洪程观测与含砂浓度历线推估模式建构(2/2)
Full Runoff River Suspended Sediment Concentration Monitoring and Development of the Sediment Hydrograph Modelling (1/2)
作者: 钟志忠
Chih-Chung Chung
国立交通大学
关键字: 泥砂浓度;时域反射法;泥砂浓度历线;suspended sediment concentration;time domain reflectometry (TDR);sediment concentration hydrograph
公开日期: 2015
摘要: 台湾每逢台风豪雨河川泥砂浓度即迅速飙升,而高浊度之水流往往对下游地区之水资源利用、河道稳定、河中构造物安全与生态系统等产生严重冲击,因此瞭解台洪期间河川泥砂浓度于时间与空间之变化实为重要课题。本计画主要建立以物理概念为基础之台洪期间河川泥砂浓度历线推估架构与方法,并配合时域反射法(Time Domain Reflectometry, TDR)河川泥砂浓度观测资料以利于相关模式之建立、检定与验证。但由目前实务观测经验发现,现场感测器避免杂物干扰与落淤等限制需要克服,此外对于提供河川横断面泥砂浓度量测规划与验证仍须进一步探讨。
Due to the steep topography and week geology conditions of watershed areas in Taiwan, the amount of the suspended sediment yield is increasing during torrential rainfall events. Accessing the continuously temporal and spatial variation of suspended sediment concentration (SSC) in river is essential and urgent for the evaluation and management of the related issues. In the traditional way, the total amount of sediment in river is often estimated using the rating curve between sediment load and river flow discharge, which is based on the statistics of observed data. This approach cannot provide the continuous hydrograph of the sediment yield and delivery from watershed during the runoff, especially under the large variation of the rainfall and renovation in field. To solve the limitation, an appropriate model which consider the physical mechanism should be developed to reveal the real time SSC hyetograph or hydrograph in advance under different rainfall or other scenarios. Furthermore, this model should be calibrated and verified with the monitoring SSC data in field. However, the most existing SSC data were observed manually under low flow discharge circumstances, leading large uncertainty in high flow discharge conditions. 
A new suspended sediment concentration (SSC) measurement method based on Time Domain Reflectometry (TDR) technique had been developed since 2006 with the support from Water Resource Agency (WRA). TDR SSC method is not affected by the soil particle size or type, and it is more economical, easy to be maintained, and applicable for high SSC monitoring. The measurement accuracy is updated to 1000 ppm after the field modifications in 2012, also a TDR SSC monitoring information platform was established to provide the real time SSC data of demonstrated stations. But, some practical problems, such as interference of debris and sedimentation in the protection pipe, were still observed in the field monitoring program.
To effectively solve these problems, one of objectives of this study is to continue maintaining and improving the field construction method of the TDR SSC measurement, and investigate SSC variation in the cross section for further requirements of obtaining the discharge-representative average SSC. New SSC probe with a carbon fiber central conductor and a minimized probe are proposed to raise the TDR SSC measurement accuracy. The open holes of field pipes are modified as well to reduce the sediment settling effect. Based on this developments, real time SSC hydrographs were provided during rainfall events. This study further reveals that the SSC variation is small and can be ignored between sampling near bridge piers and main river channel especially under the lower flow discharge condition. To extensively investigate the SSC variation in the cross section, a new design of TDR SSC monitoring setup combined with TDR scouring monitoring is suggested. Furthermore, modified modules to display advance of SSC hydrographs and vertical SSC profile are included in the information platform.
The other objective is to develop a feasible mode based on the physical mechanism to provide the continuous SSC hyetograph or hydrograph during the rainfall events. This study have already review current models and methods, then a combined model and correlated flow chart is recommended subsequently. However, this proposed approach need to consider the effect as construct the sub-region of watershed area in the first stage of simulating. Therefore, the TDR SSC field monitoring data from a small and region of watershed area in KaoPing River will be used for the SSC hyetograph modelling testing in the next step.
官方说明文件#: MOEAWRA1040063
URI: http://hdl.handle.net/11536/130471
https://www.grb.gov.tw/search/planDetail?id=11409522&docId=459846
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