Improving Strategies for Irrigation water of High Potential Contaminated Canals and Feasibility Analysis for Recreation－Case Study in Irrigation Area of Da-an River of Taichung Irrigation Association

[[abstract]]有鑑於農地及灌溉水路遭受重金屬污染的影響層面廣泛，成為農田水利事業極重視及迫切需要改善管理的重要課題；農委會頒布農業灌溉水質保護方案，針對國內遭受重金屬污染嚴重灌區劃定高污染潛勢圳路實施加強水質監測及研擬水質改善之對策。為探討如何改善農業灌溉水質遭受物染的問題，本報告以臺中農田水利會日南圳灌區為研究案例，以離子交換樹脂縮時膠囊進行水質污染來源的應用，進一步評估實施灌溉分離之工法，針對工程技術、工程效益、水質改善率、水量可靠度進行可行性分析；成果顯示工程技術可行，惟工程益本比偏低，原因為水稻經濟價值不高所致；關鍵因素為可供灌水量嚴重不足，又供灌溉水源以農地迴歸水及生活污水為主，亦即實施灌排分離工程，解決水質遭受重金屬污染問題卻製造新的問題－嚴重缺水。本文案例研究顯示決定灌排分離工程是否可行之關鍵因子為缺水；針對圳路水質改善後恢復三生功能為前提，達到休閒功能的目的的工法包含下列6項：1.生態工法營造、2.景觀工法營造、3.散步步道規劃、4.輸水路線規劃、5.生態景觀池營造、6.其他安全欄杆或緩坡設施營造。[[abstract]]The problem of heavy metals pollution in farmland and canals has wide impacts and becomes a significant issue that needs to be improved on management aspect; hence the high-pollution potential canals and irrigation area were designated, water monitoring and water quality improving were fully implement by agricultural irrigation water quality protection plan, which was promulgated by COA (Council of Agriculture). To evaluate the issue of how to improve water quality in high-pollution canals, Rinan canal irrigation area of TIA (Taichung Irrigation Association) was taken as the study area and investigated by the methods of techniques-TLRC (time-lapse resin capsule, based on the concept of ion-exchange resin). The implementation of irrigation separation method was also evaluated in this study, such as the feasibility of engineering technology, engineering efficiency, water quality improvement and water quantity reliability. The result shows that the engineering is feasible, however, the benefit ratio is low due to less economic value of crop (rice). Another critical factor is the water amount is seriously insufficient because the water source is mainly from farmland return water or domestic sewage; that is to say, if the irrigation and drainage separation project is implemented, the heavy metal pollution problem may be solved, but creates a new problem - severe water shortage. This study shows that the key factor determining the feasibility of irrigation and drainage separation project is water shortage. In the priority of improving the water quality to recover the 3-irrigation association basic functions, farmland production, environment and life, the specific water quality improving engineering contains 6 terms as follows: eco-engineering, landscape construction, promenade planning, water route planning, ecological landscape pool construction, Construction of other safety railings or gentle slope facilities