圖書典藏及影音數位平台

台灣水庫優養化情況嚴重，其中阿公店水庫被評估為嚴重優養化水庫之ㄧ，由於阿公店水庫上游集水區內丘陵佔地甚廣，耕地面積有限，又受地質影響，缺乏水分，作物生長多仰賴天雨，而在集水區超限利用之廣大濫墾地，由於不當之開發活動，造成水土流失而嚴重淤積水庫，且農業開墾除草、大量使用施肥及噴灑農藥，因降雨而流入河中，造成水中營養鹽過高，導致優養化發生。其中水體中磷的濃度高低是優養化之發生主要指標，依據環保署於阿公店水庫測點及「阿公店水庫更新改善計畫」之環境監測計畫中，監測水質項目之總磷，常有超限之清況，以卡爾森優養指數法評估，其狀態大多介於優養狀態~超優養狀態下。 由於阿公店水庫之更新計畫已完工，然而目前水庫尚屬優養化，故需改善水庫優養化之情形。

The purpose of “Improvement plan for eutrophication of Agongdian reservoir” is to simulate the eutrophication of reservoirs and to develop improvement plan by investigating the reservoir water quality, sediment, alga, point source and nonpoint source pollution, as well as to evaluate the cost-benefits of the improvement plan. The results are as follows: 1.Water quality The monitored DO, SS, TP, NH3-N and Escherichia coli are all measured up to level B standard, while it’s worse during June to September because of the reservoir cleaning process leads to the concentration of water quality and sediment lift. The water quality recovered after October when the reservoir filled water again. 2.Point source water quality The DO, SS, TP, NH3-N and Escherichia coli are all measured up to level B standard, and the heavy metal (As, Pb, Cd, Cr, Hg, Se) consistence agreed with the human protected healthy environment standard. 3.Sediment The consistence of sediment and total phosphorus at Agongdian reservoir are similar with which in Tseng-Wen Reservoir for the entire year. 4.Alga The alga analysis represents that the total alga amount increased apparently in March, gradually decreased after October. 5.Nonpoint source pollution investigation The nonpoint source investigation represents that the nonpoint source account for the most percentage to the entire year pollution, and the secondary one is the transbasin diversion, while the point source takes lower percentage relatively. 6.The eutrophication model result This project simulated the water quality by using CE-QUAL-W2 two dimensional model. The result represents a good applicability of W2 model to the water level, temperature and quality at Agongdian reservoir. 7.The eutrophication improvement plan (1)Short-term plan The objective of short-term plan is an average TSI (TP) <55 of a year. For this purpose, this project suggests regularly maintaining the existing wetlands and riverbank of Jhuoshuei River. The estimated cost for building the wetlands is 2.1 million NT dollars, 6.57 million NT dollars for the operating cost; swale building cost for swale is 161 million NT dollars; the propaganda cost for rationalization fertilizer applied technique is 0.6 million NT dollars; 30 million NT dollars for riverbank protection, and 18 million NT dollars for the maintenance cost. (2)Mid-term plan The objective of mid-term plan is CTSI <50 for Q1, Q2, and Q4, the average CTSI <55 of a year. For this purpose, this project suggests installing sewage treatment facilities, building swale in the farmland, propagandizing the fertilizer rationalization information, and maintaining the riverbank of Jhuoshuei River. The estimated cost for sewage treatment facilities are 4.94 million NT dollars; operating cost is 2.38 million NT dollars, swale building cost for swale is 485 million NT dollars; the propaganda cost for rationalization fertilizer applied technique is 0.6 million NT dollars; riverbank protection is 30 million NT dollars, and the maintenance is 18 million NT dollars. (3)Long-term plan The objective of long-term plan is an average CTSI<50 of a year. For this purpose, this project suggests continually executing technical regulations for soil and water conservation in the reservoir watershed. The estimated cost for riverbank protection is 3,630 million NT dollars, annual operating cost is 2,178 million NT dollars, groundsill work is 350 million NT dollars, annual operating cost is 3.5 million NT dollars, slope stability by vegetation is 11,070 million NT dollars, and the annual operating cost is 110.7 million NT dollars.