翡翠水庫為大臺北地區民生用水重要來源,其污染來源以非點源污染為主。結構性BMP為非點源污染最佳管理作業方法(BMP),也是目前翡翠水庫管理策略之一。本研究調查翡翠水庫既有結構性BMPs,應用地理資訊系統(GIS)以及暴雨管理模式(SWMM),規劃並模擬保護帶(Buffer Strip)及既有結構性BMPs穩定運作狀況下對翡翠水庫集水區非點源污染削減量,模擬水質包含懸浮固體(SS)、總磷(TP)及生化需氧量(BOD)。研究結果顯示,在蓄水範圍四周設置50公尺保護帶時,設置保護帶的子集水區SS輸出削減率超過80%,TP削減率超過50%,BOD削減率達到70%。保護帶設置對整個翡翠水庫集水區,此三種水質削減率最高可達5%。另外利用Vollenweider公式模擬保護帶設置對水庫水質影響,若以水庫總磷濃度10μg/L為目標值,則集水區總磷污染量尚需削減19.0%~22.2%。考慮現有狀況下設置50公尺保護帶及既有污染削減措施穩定運作下可削減總磷每年約800公斤,佔目標削減量1/3-1/4。除了設置保護帶及現有結構性BMPs外,尚需透過其他非點源污染控制措施才能達到此削減量。
The Feitsui reservoir is the drinking water source for Taipei metropolis, and the nonpoint source pollution has been considered as an important issue. The Structural BMP is one of the best management practice (BMP) and is used in Feitsui reservoir management. In this study, we investigated the existing structural BMPs in Feitsui reservoir, and also integrated geographic information systems (GIS)and Stormwater Management Model (SWMM) to planning and assess the effects of buffer strips and the existing structural BMPs which in the condition of operating stably in Feitsui reservoir. The major water quality items contain suspended solids (SS), total phosphorus (TP) and biochemical oxygen demand (BOD). The results show that 50 m width of the buffer strips around the reservoir can reduce 80% of SS, 50% of TP, and 70% of COD for the subwatersheds with buffer strips. For the entire watershed, the 50m buffer strips mitigate up to 5% of pollutants. In addition, Vollenweider model is utilized to assess water quality in the reservoir and the results show that 19-22% of pollution reduction rate is required to achieve the goal of 10μg/L of TP. The 50m width of buffer strip and existing structural BMPs in the best condition of operating stably can contributed 1/3-1/4 reduction loads, which is 800 kgTP/yr. More BMPs in addition to BMP are necessary in the Feitsui reservoir watershed management.