QUAL2K和WASP模擬河川含高氨氮與高有機物質之模擬成果差異性研究

A Study on the Variations of Model Performance between QUAL2K and WASP for a River with High Ammonia and Organic Matters

湯平貴(Ping-Kuei Tang)

指導教授 ： 黃益助

國立屏東科技大學/工學院/環境工程與科學系所/博士(2013年)

https://doi.org/10.6346/NPUST.2013.00094

摘要

研究應用River and Stream Water Quality Model (QUAL2K)及Water Quality Analysis Simulation Program (WASP)水質模式，利用相同水質生化參數，探討長期監測(1965~2012年)、2012年11月25日、27日、12月4日及8日等同期連續四次監測、2008年4月13日、2010年10月9日及2012年1月7日等單日監測資料，在不同距離下進行驗證與率定工作，並在此基礎下進行敏感度、容許排入量及成本結構的差異性分析，經由率定、驗證、再驗證等程序，研究結果顯示，兩種水質模式皆可適用於東港溪流域，且利用平均絕對百分誤差法(Mean absolute percentage error, MAPE)評估結果顯示大部份水質模擬成果都在可接受範圍。後續並選用清潔養豬、廢水處理、淺床式礫間接觸氧化法及人工濕地等處理技術，進行污染削減改善工作及成本分析比較。
經由敏感度圖型分析證明所選用之水質生化參數，可適用於不同河段或段落的劃分方式，或者用於長短期水質水量的變化分析，其中顯示在非感潮河段延散係數以QUAL2K模式包容性較大。在容許排入量分析方面，使用同一種水質模式，研究顯示豐水期與枯水期有明顯差異，以枯水期較小，約僅有豐水期的三分之一，其中溶氧在枯水期則有不符合乙類水體水質標準之現象；當以不同水質模式觀察分析，兩種水質模式模擬容許排入量由大而小排列比較，差異性約在23%左右。
本研究以現場及實驗方式取得東港溪之關鍵性水質生化參數，除延散係數是以WASP模擬導電度求得外，其餘四種水質生化參數則以QUAL2K經由模擬率定及驗證結果，以圖形方式轉入WASP使用，從各項模擬結果觀察，此種轉換可適用於東港溪流域之模擬，誤差值約在3%合理範圍以內，產生誤差原因係支流負荷進入不同網格之遲滯效應所造成。從整體評估結果顯示，包含率定、驗證、再驗證、敏感性分析、容許排入量分析、成本分析，都顯示WASP比QUAL2K模式具有較大的優勢，惟以QUAL2K模式操作方式較為簡單。

關鍵字

河川污染指數 ； 平均絕對百分誤差法 ； Water Quality Analysis Simulation Program (WASP) ； River and Stream Water Quality Model (QUAL2K) ； 容許排入量 ； 清潔養豬

並列摘要

Two water quality models, QUAL2K (River and Stream Water Quality Model) and WASP (Water Quality Analysis Simulation Program), were employed to calibrate and verify the biochemical parameters spatially and temporally based on the data collected from 1965 to 2012, four surveys sampled on 25, 27 of November and 4, 8 of December in 2012, and three surveys in March 13 of 2008, October 9 of 2010, January 7, 2012. Furthermore, sensitivity evaluation, allowable discharge amounts, and cost analysis were also conducted. Through the calibration, validation, and re-validation processes, two selected water quality models are identified as applicable to the Tungkang River basin. The model results were reasonable evaluated by the mean absolute percentage error (MAPE) method. Several feasible preventive measures such as promotion of clean pig farming practices, wastewater treatment facilities, shallow bed gravels contact oxidization process as well as constructed wetlands were proposed to improve the water quality of the Tunggang River by cutting down the pollutant loading.
Through the sensitivity diagram analysis, the selected biochemical parameters of water quality can be applied to various modes of reaches or segmentation and to long-term or short-term water quality variations. QUAL2K possessed a better tolerance to dispersion coefficient within the non-tidal reach. The results showed that the allowable discharge amount significantly varied between the wet and dry seasons. Allowable discharge amount during the dry season was only one third of that during the wet season. Dissolved oxygen during the dry season was frequently not to meet the Class B water quality standards. The variations of allowable discharge amount were around 23% between WASP and QUAL2K to achieve the Class B water quality standards regulated by Taiwan EPA.
In this study, biochemical coefficients were collected from field sampling and laboratory tests as inputs to the QUAL2K and WASP/EUTRO models. Except dispersion coefficients were obtained using the conservative electric conductivity (EC) via model calibration, the other four biochemical coefficients were calibrated and validated by QUAL2K, and then transferred to WASP model with graph method. Graph transformation is applicable in the water quality simulation of the Tunggang River with 3% error which is within a reasonable range. The error may attribute to the lag effects of the drainage pollutant loads transporting into various grids. Overall, the model results including calibration, validation, re-validation, sensitivity evaluation, allowable discharge amount, cost analysis of WASP works better than those of QUAL2K which possesses the advantage of easier operation.

並列關鍵字

RPI (River Pollution Index) ； MAPE (Mean Absolute Percentage Error) ； WASP (Water Quality Simulation Program) ； QUAL2K (River and Stream Water Quality Model) ； allowable discharge amount ； clean pig farming practice

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