摘要 本研究主要利用CE-QUAL-W2模式，模擬石門水庫遭受污染及水位激烈改變下之水理、水質變化情形。以民國90年之實測資料作為模式參數檢定的依據，而以民國91年之資料作驗證，並進行模式參數之敏感度分析。之後考慮水庫不同入流量及污染負荷情況下對水理及水質之影響，如此便可得知模式於石門水庫之適用性。 結果分析顯示，以CE-QUAL-W2模式模擬石門水庫之水位、水溫及流場等水理現象，其結果大致良好。在模擬各項水質項目中，以溶氧之模擬結果與實測值最接近，再來依次是總磷、氨氮、葉綠素a及硝酸氮，整體而言，模擬結果尚可。民國91年2〜6月為水庫水位急遽下降時期，其水質變化由模式模擬反映出：葉綠素a濃度有明顯上升的趨勢；總磷與硝酸氮因藻類吸收利用，使得濃度下降；溶氧隨著藻類劇增而有降低現象；氨氮主要因暴雨逕流而使水庫污染負荷增加。參數敏感度分析結果，以藻類飽和生長率（AG）、飽和日光強度（ASAT）、藻類呼吸率（AR）、光消減係數（EXH2O）及藻類沉降率（AS）此五個參數對模式輸出結果影響較為顯著，在模擬過程中應慎選使用。 Abstract This research simulates Shin-Men Reservoir’s hydrodynamics and water quality under suffering polluting and dramatic variation of water level by applying CE-QUAL-W2 model. This study is performed by applying year 2001’s in-situ measurement to be the accordance of model’s parameter’s test, and using year 2002’s in-situ measurement to be the calibration of model’s parameter and sensitivity analysis. Considering different inflow and pollutant loading’s effects to hydrodynamics and water quality to evaluate the suitability of the model in Shin-Men Reservoir. The result is acceptable in the prediction of the water level, water temperature, fluid dynamics simulated by CE-QUAL-W2. Among the items of water quality simulated, the dissolved oxygen (DO) is the most adequate, and the phosphorous (TP), ammonium nitrogen (NH3-N), chlorophyll-a (Chl-a), and nitrate nitrogen (NO3--N) are at acceptable. During the dramatic decrement period of water level between year 2002 Feb. to Jun., the model’s result shows: Chl-a runs the obviously uptrend, TP and NO3--N become low concentration for the algal absorb, DO decreases by algal’s breeding, NH3-N increases due to the reservoir pollutant loading by storm and runoff. The result of sensitivity analysis shows that the algal saturation growth rate (AG), saturation light intensity (ASAT), algal respiration rate (AR), light extinction coefficient (EXH2O), and algal settling rate (AS) are notable to model simulation, should be selected cautiously.
