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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Author: search.filters.author.Chung, Chih-ChungSubject: search.filters.subject.Sediment transport

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    Monitoring of Sediment Transport in a Reservoir using Time Domain Reflectometry
    (2013-01-01)
    Chung, Chih-Chung
    ;
    Lin, Chih-Ping
    ;
    Wu, Po-Lin
    ;
    Hsieh, Sheau-Ling
    ;
    Wu, Ching-Hsien
    Due to geological weathering and climate change, soil erosion in watershed is becoming a serious problem in Taiwan. Large amount of sediment transports to reservoirs during typhoon events and affects the water quality. Density currents in reservoirs have high sediment concentration. The accumulated sediments have significantly reduced the reservoir capacity. Monitoring of sediment transport in a reservoir plays an important role in reservoir management. The existing techniques for suspended sediment concentration (SSC) monitoring, such as optical and acoustic methods, are sensitive to particle size or limited in measurement range. Furthermore, these techniques may not be cost effective for field monitoring due to the required maintenance and spatial coverage. A new technique based on time domain reflectometry (TDR) was recently introduced. It possesses several advantages including particle-size independence, low-cost transducers, durability, and cost-effective multiplexing. This study modified the TDR technique for better field applicability and demonstrated how it can be deployed as a full monitoring program for reservoir management through a case study in the Shihmen reservoir, Taiwan. Monitoring stations at upstream riverbank and outflow channels were installed with fixed protective structures to provide inflow and outflow sediment-discharge records. To capture the characteristics of density currents, multi-depth monitoring stations were designed and deployed on floats in the reservoir. Some of the data collected during Typhoon Fung-Wong are presented as an example to demonstrate the effectiveness and benefits of the monitoring station.
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    Item type:Item,
    High concentration suspended sediment measurements using time domain reflectometry
    (2011-04-20)
    Chung, Chih-Chung
    ;
    Lin, Chih-Ping
    ;
    土木工程學系
    ;
    防災與水環境研究中心
    ;
    Department of Civil Engineering
    The existing methods of suspended sediment concentration (SSC) monitoring provide a measurement accuracy significantly influenced by the particle size of suspended sediments, function only under limited measurement range and are not cost effective for field maintenance as well as wide spatial coverage. The paper introduces an innovative SSC monitoring methodology based upon time domain reflectometry (TDR), especially emphasizing on optimum TDR measurement accuracy investigated theoretically and experimentally. Pertinent probe design, probe calibration, as well as data reduction procedures were proposed. Ultimately, the approach can achieve the measurement accuracy to adapt the derived hardware resolution and beyond. In addition, the performance evaluation was carried out considering possible influence factors including water salinity, sediment types and particle sizes, and leading cable lengths. TDR SSC measurements indicate insensitive to sediment particle sizes. After proper calibration, the measurements are also insensitive to water electrical conductivity and not affected by leading cable resistances. There are further advantages of the TDR method including high measurement range from 2 to at least 300 g L(-1), easy calibration, robustness, maintainability, and cost-effective multiplexing. (C) 2011 Elsevier B.V. All rights reserved.