台灣地區近年來工業廢水與都市污水遽增,但大多數卻無專屬的污水道可供排放,因此大量廢污水均利用原有的灌溉水路作為排放之途徑;現今,雖相關單位十分重視水質管理之問題,對非法排放廢污水之排泄戶已嚴格取締管制,但仍有部分灌溉水質受污染之問題無法解決,除了不肖業者的非法偷排與水質標準規定不一外,最根本問題在於灌溉用水與排放水共用相同水路所導致。 本研究針對這灌排共用而導致灌溉水質受污染之問題,首先依據現階段水質管理作業之程序與台灣地區相關之法令為基礎,重新建立一套防止灌溉水質受污染之處理程序,並進而研擬出當灌溉水質已遭污染時是否該採用工程改善方案來改善之步驟流程。至於工程改善方案,將分水源或引水處遭受污染與廢污水直接流入灌溉系統二種型態,並分別討論其可行之改善方法;此外,為使工程改善方案之實施可合乎效益之準則,進而建立出一套評判之標準,採用「益本比」與「決策-權重分析」來評估其直接與間接效益。 最後,選定一污染嚴重之地區---桃園黃墘溪流域為案例來作分析,討論其區域概況、污染情形、可行之工程改善方案、及經濟效益評估等,期藉此可作為日後改善灌溉用水品質、防止農地遭污染問題時之參考。
Recently , the industrial and urban waste water has increased dramatically in Taiwan , but there is no exclusive sewage systems in most area . As a result , most of these waste water is directed through existing irrigation systems . Irrigation water quality always receives strong attention by the related authority , and heavy finds have imposed on illegal waste water discharge , but illegal discharge is not stop . The basic problem is that there is no separate system for irrigation and sewage water . This research is to study the problem aroused by using the same system for irrigation and sewage water , based on the current related laws and standard operating procedures for water quality management . Then a new operating procedure is set up to prevent the pollution from irrigation water , and whether improvement is needed . Two improvement methods are proposed based on whether the irrigation water is polluted directly or indirectly . In order to make the improvement more feasible , two rules , ” Cost Benefit Ratio ” and “ Decission-weighting Analysis ” are applied . Finally , seriously polluted Taoyuan Huang Qian Stream basin is taken as an example . Its current pollution situation , improvement and economic benefit are discussed.