寶山水庫非點源污染控制多目標模式之建立

Abstract

農業非點源污染所帶來的總磷量占污染水體中總磷量的大部分，故被列為改善水庫、湖泊水質及優養化之重要管制項目。農業非點源污染可藉由最佳管理作業(BMP)來進行控制，適當的BMP可減少伴隨逕流之污染物而達到降低非點源污染的目標。本研究應用農業非點源污染模式(AFNPS)模擬水庫集水區之非點源污染負荷與BMP效益，並依模擬結果建立一個考量成本、磷、沈質與公平性四目標之混合整數規劃模式，以進行水庫非點源污染控制之多目標分析。本研究以寶山水庫為案例研討區，找出適用該案例區域的BMP方案之施行成本與去除效率，依據所發展的多目標BMP優選模式，於不同的成本限制下，分別比較在磷、沈質與公平性各目標下所得結果之差異性與優劣點，並進一步求出非劣解集合，探討不同控制目標間之權衡(Tradeoff)的關係。結果顯示本研究建議之模式較過去所建立之磷肥管制策略模式，除了可明顯獲得較具經濟效益之方案外，更有助於沈質與公平性目標之達成。

phosphorus loads brought from agricultural non-point source (NPS) pollution significantly degrade the water quality of a reservoir. Adequate control of agricultural non-point source pollution is therefore necessary for improving the water quality. Controlling non-point source pollution is generally accomplished by various Best Management Practices (BMPs). This study applied the agricultural non-point source pollution (AGNPS) model to simulate NPS loading and BMP efficiencies for the watershed of Po-San Reservoir, an off-stream reservoir. According to the simulated results, a multiobjective mixed integer programming model was established for NPS control strategies analysis. Cost, phosphorus load, sediment load and equity were the four maior objectives considered. A case study for Po-San reservoir was inplemented. Four applicable BMPs were chosen based on the characteristics of the studied area. Non-inferior solutions were obtained using the constraint method. The trade-off relationship among different control objectives was described and discussed. While compared with the previously proposed fertilizer control model, the result shows that the established model is more cost- effective and is able to achieve better sediment reduction and equity goals.