水體重金屬總量管制施行之評析—以桃園埔心溪為例

Abstract

民國105年2月桃園成為台灣第一個以重金屬為指標污染物施行總量管制的地方，由於初次施行應尚有許多可以修正檢討之處。本研究目的在於評析我國總量管制發展與策略，過程中將檢視桃園地區總量管制劃設範圍，並以Water Quality Analysis Simulation Program（WASP）推估桃園埔心溪流域中三塊厝支線水體的涵容能力，並利用模擬結果估算進入其下游農地之重金屬污染量，評析劃設之適當性。 以WASP水質模式兩次驗證結果，MAPE分別為49.27%及44.56，而R2值分別為0.87與0.91，都代表著此模式能合理預測，且模擬結果與實際情形有高度相關性。而以WASP水質模式模擬三塊厝支線水體對銅重金屬之涵容能力結果顯示，現行管制策略仍無法使三塊厝支線下游段水體符合灌溉水水質標準，此水體仍供灌著約114公頃農地，因應調整一級總量管制標準管制之界限將主要污染源納入，方可使其達成水體使用目的。另外以模擬結果估算每年進入三塊厝支線下游農地的重金屬污染量，發現若以現行二級總量管制標準管制之，則一般農地安全使用年限僅約48年，而改以一級總量管制標準管制之，則農地安全使用年限可增長至128年。利用地理資訊系統ArcGIS展示統計資料結果，有助於視覺化之說明與溝通。 此論文結果可為桃園地區總量管制策略修正或新劃設區域實之參考依據，另也提供作為未來評析其他地區總量管制施行策略適當性之方法。

In Feburary 2016, Taoyuan became the first city in Taiwan to implement Total Quantity Control Methods for heavy metal contamination control in water. The purpose of this study is to analyze the strategy, including reassessing the area of delineation, quantifying the allowable pollutant load by using WASP model and calculating the mass of heavy metal contaminants in the farmland through irrigation water. WASP model in this study applies MAPE and R2 for verification. Of the first result of verification, MAPE measures 49.27%, R2 meassures 0.87; the second, MAPE measures 44.56%, R2 meassures 0.91. The two sets of results showed that the WASP model provides reasonable predictions matching current conditions. The results of WASP modeling showed that the allowable pollutant load of SanKuaiCuo channel still fails to meet ” Irrigation Water Quality Standards.” This will be solved by enhancing the level of Total Quantity Control Methods from 2nd-level to 1st-level. The WASP results indicated that farmlands around SanKuaiCuo channel are increased by 80 years from 48 to 128 when the 1st-level Total Quantity Control Methods is implemented. Applying ArcGIS for statistical data display helps provide visualized content for clearer presentation. The study can serve as reference for adjustments of the implementation of Total Quantity Control Methods in Taoyuan and other areas in the future.