台灣地區由於地文及水文特性之影響，且每年平均約3.5次遭逢颱風侵襲，並隨著氣候變遷影響，使得極端暴雨事件頻傳，一旦暴雨發生時即挾帶大量泥砂進入水庫及湖泊等內陸水體，造成原水濁度過高導致民生用水供應失衡。因此，如何有效掌握懸浮泥砂濃度分布情況，成為進行最佳管理、決策及分析之首要。
隨然目前遙測技術已廣泛應用於懸浮泥砂濃度監測，但其定量反演算法，仍多屬經驗方法及半分析方法，而分析方法建立於生光模式及輻射傳輸等理論基礎之上，唯有進行懸浮泥砂IOPs高精度量測，方可提高反演模式準確度。隨著光學儀器的發展，本研究利用ac-s光譜儀並建立室內水槽試驗光學量測方法，並將石英砂經標準篩網分類取得#200 ~ #300(0.075 ~ 0.048 mm)、#300 ~ #325(0.048 ~ 0.045 mm)及#325 ~ #400(0.045 ~ 0.038 mm)等三種粒徑(以下簡稱為D1、D2及D3)，用以進行粒徑及濃度變化之懸浮泥砂吸收及散射係數光譜特性研究。
根據研究分析結果發現：
(1)吸收及散射係數明顯與懸浮泥砂濃度成正比關係，隨濃度增加而增加，且證實比吸收及比散射係數與粒徑一次方成反比關係，即粒徑D1>D2>D3，則a*D1< a*D2< a*D3或b*D1< b*D2< b*D3 。
(2)吸收係數光譜特性不受濃度及粒徑變化而影響，皆呈指數型態隨波長增加而遞減。散射係數光譜特性在粒徑變化上，呈現兩種曲線型態；D1粒徑之光譜曲線存在明顯波峰及波谷現象，且短波長400 ~ 500 nm之峰值隨濃度增加而往長波長方向漂移；D2及D3粒徑之光譜曲線呈直線型隨波長增加而遞增。
(3)利用比吸收係數與粒徑一次方反比關係進行粒徑分布推估，則D1之粒徑分布為0.062±0.0019 mm，且指數衰減係數Sd為0.0078；而D3之粒徑分布為0.040±0.0004 mm，且指數衰減係數Sd為0.0088。

Taiwan locates in a subtropical area with steep slopes and short rivers and receives an abundant annual rainfall of 2,493 mm. However, the precipitation with uneven distribution over time and space leads to frequent floods and droughts. The global average temperature is increasing by the globally climatic change. Due to the natural disasters and over-explorations, a considerable change has been observed in the water catchment areas of many rivers upstream in Taiwan during the past few years. When the heavy rain occurs, the debris flow and mudslides are usually flushed from the areas of steep terrain to the reservoir, resulting in a dramatic increase in turbidity and the shortage in supplying the use of domestic water. Therefore, how to keep abreast of suspended sediment concentration distribution, and carrying on the best management, decision-making and analysis are important.
There are a number of alternatives for the design of a case 2 water algorithm with the capability to decompose the inherent optical properties (IOPs) into contributions by different water constituents. Radiative transfer modeling provides a systematic means of determining the effect of changes in the optical properties of water on underwater light fields and remote sensing reflectance signals. One of the key solutions is under the IOPs of suspended sediment investigation and measurement. In recent years, the combination of commercially available software such as Hydrolight and new in situ spectrophotometer for measuring IOPs has enabled greatly improved radiative transfer models to be constructed.
The size of suspended sediment in the inland waters is an important factor for optical monitoring method. A water tank was used for all experiments, and the interior surfaces were painted black to minimize extraneous reflectance of light. This study made use of ac-s (WetLabs Inc.) to measure the absorption coefficients of different sediment sizes. The sediment size of #200 ~ #300(0.075 ~ 0.048 mm), #300 ~ #325(0.048 ~ 0.045 mm) and #325 ~ #400(0.045 ~ 0.038 mm) were choose to conduct water tank experiment. The purpose of the research was to investigate the relationships between and among IOPs, sediment size, and suspended sediment concentration (SSC).
The results of this study includes (1) the absorption coefficient and scattering coefficient increase with increasing SSC, then the specific absorption coefficient and specific scattering coefficient were inverse proportion relationship with particle size of suspended sediment; (2)the absorption spectrum generally decreases, often exponentially, with increasing wavelength. The scattering spectrum of coarse particles occurs clearly peak and trough phenomenon across the visible wavelength, and the wavelength of peak shifted from 430 to 463 nm as SSC increased from 450 to 660 mg/l. The scattering spectrum of fine-grain was linear with increasing wavelength; and (3) the results of retrieve particle size were that D1 was 0.062±0.0019 mm and then Sd was 0.0078; D3 was 0.040±0.0004 mm and then Sd was 0.0088.

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