水體濁度觀測為水環境及水資源領域中之例常觀測項目,泥沙濃度則為水資源及水利工程中重要之水文觀測資料。濁度資料對於水生態環境、水資源利用評估及公共用水營運,為極重要判別指標;另一方面,泥沙濃度資料則為集水區保育及河道穩定評估規劃所需之重要基本資料。濁度觀測方式及儀器,相對於傳統泥沙之觀測,其儀器具備自動記錄、即時傳輸功能、自動化程度高、價格較低及設站普遍之優點,且其觀測記錄年、資料量普遍累積較長。雖河川中懸移泥沙濃度與濁度之物理定義不同,但在工程實務應用上仍有許多泥沙濃度資料以濁度資料來替代表示。本文目的在於研究特定水沙條件下之濁度與濃度率定關係,並以石門水庫泥沙為案例,探討試樣水體濁度、濃度觀測數值在不同含沙量條件下之對應及量化關係規律,並依ISO標準規範,進行不確定度分析及誤差分析。研究成果顯示,濁度觀測方式之重現性及精度良好,且濁度與濃度測值間對應率定關係明確,但此率定關係與泥沙粒徑及分布組成條件密切相關。
Turbidity is a commonly monitored parameter in environmental and water resources investigations, whereas sediment concentration is one of the primary field data needed in water resources and hydrological engineering. The turbidity data is an essential indicator for assessing the quality of aquatic habitat or the utilization of water resource or management of water use. Sediment concentration, on the other hand, is the basic information fundamental to watershed protection and stream channel stabilization. Method and apparatus used for monitoring turbidity, compared to those of sediment concentration, have many advantages, such as being highly automatic, capable of instant recording and data transmitting, low cost, and flexible setup at observation stations. In addition, continuous turbidity measurements can be done for periods of years, accumulating considerable amount of data. Despite of having different physical definitions, turbidity has been used as a surrogate of suspended sediment concentration in some engineering applications. This paper is to study the rating relations between turbidity and suspended sediment concentration under given water-sediment combinations. Using the Shi-Men Reservoir as case study, we investigated and quantified the rating relations between turbidity and suspended sediment concentration samples collected under different field conditions. Based on the ISO standard, uncertainty analysis and error analysis are conducted. The results indicate that the turbidity monitoring method demonstrates good repetitiveness and precision, and a distinct relation between the sampled turbidity and concentration. The rating relation is closely related to sediment size and sediment particle size distribution.