|標題：The Innovation of Irrigation Water Quality Evaluation Program in Taiwan|
|作品名稱||The Innovation of Irrigation Water Quality Evaluation Program in Taiwan|
|著者||虞國興; 舒文斌; 何逸峰|
|摘要||he aim of irrigation is to supply water to crops at right times with adequate quantities and appropriate qualities. Thus, the quantity and quality of water for irrigation use are of equal importance. Availability of irrigation water resources nowadays is increasingly constrained, as a result of climate change, population growth, and industrial and commercial developments. Therefore, the need of quality management for the limited available irrigation water supply is increasingly urgent. In Taiwan, presently more than 2,500 monitoring points have been set up on various irrigation canals, for examining and recording the water quality conditions, such as temperature, acidity, and electrical conductivity once in every other month. The monitored results of the irrigation water quality for a specific irrigation association or system are then compiled and analyzed to calculate the qualified ratios of its irrigation water, or the ratios of amounts of water that meet the water quality criteria for irrigation to the total amount of irrigation water supplied in a certain period. Conventionally, the qualified ratio is calculated by means of the “Monitoring Point-Frequency Method” (MPF method). However, in this method is not taken into comprehensive consideration of the different background characteristics of the monitoring points, such as affected irrigation areas, irrigated water amounts, cropping patterns, etc. As such, neither the substantial present conditions of water quality nor the canals with inferior water quality can be factually reflected from the statistic data obtained from the MPF method. Consequently, the subsequent water quality management cannot be implemented systematically and effectively. Thus, the performances of water quality improvement measures achieved are usually incompatible to the relevant resources inputs ever made. |
In order to solve the shortcoming of the MPF method, in this study was proposed the “Weighted Irrigation Canal-Area Method” (WICA method), by taking into account the characteristics of irrigation areas in the monitored results. This method was applied to calculate the ratio of irrigation water in each canal fulfilling the water quality criteria, by integrating the irrigation area of the canal as a weight factor into the method. In the study was also developed a four-tier framework of “irrigation association - irrigation system - canal - monitoring point” for better realizing the water quality conditions in each canal. Furthermore, the irrigation water quality was classified into four grades; namely, good, qualified, unqualified, severely polluted for each canal, which was certainly helpful to the relevant irrigation associations to take appropriate management measures upon the actual water quality conditions of the irrigation canal rated.
The irrigation water quality evaluation mechanism developed from this study has been approved by the competent authority and then implemented in Taiwan area since early 2009. In this paper is not only systematically introduced various measures used in this evaluation mechanism, but also summarized its preliminary achievements as of to date.