評估蒸發皿係數以推估台灣南部地區蒸發散量之研究

Evaluation of Pan Coefficients for Estimating Reference Evapotranspiration in Southern Taiwan

葉信富(Hsin-Fu Yeh) ； 李振誥(Cheng-Haw Lee) ； 陳忠偉(Jung-Wei Chen) ； 張格綸(Ke-Lun Chang)

《農業工程學報》 54卷3期 (2008/09) Pp. 27-35

https://doi.org/10.29974/JTAE.200809.0003

摘要

在水資源規劃中，對於蒸發散量(ET(下標 ref))之評估通常依據氣象部蒸發皿之蒸發量資料，可利用蒸發皿蒸發量(E(下標 pan))與蒸發皿係數(K(下標 pan))來計算蒸發散量(E(下標 ref)=K(下標 pan)×E(下標 pan)。但近年來受全球氣變適遷影響，舊有蒸發皿係數未能反映現今環境條件下之蒸發散量。蒸發散量之推估已經發展出許多方法。本研究以聯合國糧食用農業組織(FAO)建議之Penman-Monteith法爲最佳估算方法。本研究以台灣南部地區6個氣象觀測站作爲研究案例，蒐集1990-2004年之氣象資料評估蒸發散量及蒸發皿蒸發量，並探討皿蒸發係數之區域空間分布。結果顯示在台灣南部地區參考蒸散量與蒸發皿蒸發量有相同的趨勢分布，蒸發散量呈現南低北高的情況。另外在蒸發皿係數方面，K(下標 pan)值也都有區地或性與秀節性的變化。此分布情況可以正確的評估出眞實蒸發散量做爲區域水文評估及管理之參資訊。

關鍵字

參考蒸發散量 ； 蒸發皿係數 ； Penman-Monteith

並列摘要

Evaporation pan (E(subscript pan)) data are often used to estimate reference evapotranspiration ET(subscript ref) for use in water resource planning. Generally, ET(subscript ref) is estimated as the product of the E(pan) data and a pan coefficient (K(subscript p)) (ET(subscript ref)=K(subscript p)×E(subscript pan)). In recent years, under the impact of global climate change, the early studies on K(subscript pan) didn't response to current climatic situation. However, reliable estimation of ET(subscript ref) using E(subscript pan) depends on the accurate determination of K(subscript pan). Many different methods for estimating ET(subscript ref) have been developed, among which the Penman-Monteith method is demonstrated to be especially excellent by the Food and Agriculture Organization (FAO). In this study, the Penman-Monteith reference evapotranspiration, pan evaporation, and pan coefficient are calculated, compared and regionally mapped at six meteorological stations during 1990-2004 in Southern Taiwan. Their spatial distribution and temporal are examined and discussed. The results show the reference evapotranspiration and pan evaporation have similar regional distribution patterns in the southern Taiwan both with the highest values being in the lower region and the lowest values being in the upper region. This distribution pattern provides valuable information for regional hydrological studies since it is one of the most important factors determining regional actual evapotranspiration, which, in turn, is key parameter in regional water resources assessment and water management.

並列關鍵字

Reference evapotranspiration ； Pan coefficient ； Penman-Monteith