連續型機率分配模式應用於台灣灌區有效雨量之推估

Using the Model of Continuous Probability Distributions to Estimate the Effective Rainfall of Paddy Fields in Taiwan

陳豐文(Feng-Wen Chen) ； 劉振宇(Chen-Wuing Liu) ； 蔡西銘(Shi-Ming Tsai)

《農業工程學報》 59卷2期 (2013/06) Pp. 1-28

https://doi.org/10.29974/JTAE.201306_59(2).0001

摘要

有效雨量為潛在的灌溉用水來源，台灣地區估算及應用有效雨量以水庫取水灌溉型灌區為主，皆於年度灌溉計畫擬定時將有效雨量納入估算計畫灌溉用水量並預先扣除，其他非水庫取水型灌區則較不重視雨量之利用，現今面臨水資源開發及調配日益困難之際，有效雨量如能善加利用作為灌溉水源之一，期能對整體水資源調配有所助益。本研究以水門操作法計算應用於灌溉之有效雨量，並優選連續型機率分配模式推估計畫有效雨量。本文採用桃園、臺中、高雄、臺東灌區1981-2000年（共計20年）雨量資料評估台灣北部、中部、南部、東部地區之降雨特性、有效雨量利用率及有效雨量利用效益。結果顯示桃園、臺中、高雄、臺東灌區等之年有效雨量平均值分別為1005 mm/yr、802 mm/yr、809 mm/yr、827 mm/yr；年有效雨量利用率分別為54.9%、53.6%、41.0%、49.6%；另應用連續型機率分配模式推估53個工作站1-12月的月計畫有效雨量， 636次的演算結果顯示月計畫有效雨量分佈型態以伽瑪分佈為主、其次為常態分佈型態、少數為20年倒數第5位法。

關鍵字

灌溉用水 ； 有效雨量 ； 計畫有效雨量 ； 水門操作法 ； 連續型機率分配模式

並列摘要

Effective is a potential source of water resource for irrigation, the estimation and utilization of effective rainfall are predominantly based on the irrigation area of reservoir systems in Taiwan. The effective rainfall is always previous estimated and listed in the annual irrigation scheduling of each Irrigation Associations in Taiwan, It is used to forecast the potential available rainfall for irrigation and conducted to deduct the irrigation water in the next year. But the irrigation area of non-reservoir is de-emphasis on the utilization of the natural rainfall. Whereas the water resources are increasingly difficult to develop and deploy in Taiwan, the appropriate usage of effective rainfall will be helpful to improve the whole water resource problems which of the effective rainfall is regarded as one source of irrigation water. In this study, Taoyuan, Taichung, Kaohsiung and Taitung irrigation areas are selected as the research region. Water gate operation method and the continuous probability distribution methods are conducted to evaluate the effective rainfall and planned effective rainfall, respectively. The 20-year long daily rainfall data in the period of 198 1-2000 are used to estimate the rainfall characteristics, utilization rate and use efficiency of effective rainfall in the northern, middle, southern, and eastern of TaiwanThe result shows that the average of annual effective rainfall is 1,005 mm/yr, 802 mm/yr, 809 mm/yr, and 827 mm/yr respectively in Taoyuan, Taichung, Kaohsiung, and Taitung irrigation areas. The corresponding utilization rate of annual effective rainfall is 54.9%, 53.6%, 41.0%, and 49.6%, respectively. Further, the continuous probability distribution method was conducted to estimate the monthly planned effective rainfall of 53 workstations from January to December. According to the result of 636 times of mathematical calculation, it shows that the optimal distribution of monthly effective rainfall is primary characterized by Gama distribution, the subsequent models are the normaI distribution, and the fifth least value of the monthly effective rainfall for the past 20 years.

並列關鍵字

Irrigation water ； Effective rainfall ； Planned effective rainfall ； Water gate operation method ； Continuous probability distributions