Assessment of Spatial and Temporal Distribution of Reference Evapotranspiration and Pan Evaporation in Taiwan

台灣地區蒸發散量及皿蒸發量時空分布之評估

葉信富(Hsin-Fu Yeh) ； 林宏奕(Hung-I Lin) ； 李振誥(Cheng-Haw Lee)

《農業工程學報》 59卷3期 (2013/09) Pp. 13-21

https://doi.org/10.29974/JTAE.201309_59(3).0002

摘要

在水文循環中，蒸發散在水圈及大氣圈的轉換過程中扮演一個很重要的角色，在水資源規劃方面，對於蒸發散量（ETref）之評估通常依據氣象站蒸發皿之蒸發量資料，可利用蒸發血蒸發量（Epan）與蒸發血係數（Kp）來計算蒸發散量（ETref=Kp × Epan）。但近年來受全球氣候變遷影響，舊有蒸發皿係數未能反映現今環境條件下之蒸發散量。本研究收集台灣地區20個氣象觀測站資料（1990－2008年）評估比較台灣地區蒸發散量及蒸發皿蒸發量，並探討皿蒸發係數之區域空間與時間分布。結果顯示在台灣地區在乾濕季時之參考蒸散量與蒸發皿蒸發量有相同的趨勢分布，蒸發散量呈現西南部較高而中部地區較低的情況。另外在蒸發皿係數方面，Kpan值也都有區域性與季節性的變化。此分布情況可以正確的評估出真實蒸發散量做為區域性水文評估及管理之參考資訊。

關鍵字

蒸發散量 ； 蒸發皿係數

並列摘要

Evapotranspiration (ET) is an important process of water transfer in the hydrosphere and atmosphere; it plays an active role in the hydrological cycle. Evaporation pan (Epan) data are often used to estimate reference evapotranspiration (ETref) for use in water resource planning. Generally, ETref is estimated as the product of the Epan data and a pan coefficient (Kp) (ETref = Kp×Epan). In recent years, due to global climate change, the early studies on Kpan have not reflected the current climatic situation. In this study, the Penman-Monteith reference evapotranspiration, pan evaporation, and pan coefficient are calculated, compared, and region ally mapped at twenty meteorological stations during 1990-2008 in Taiwan. Their spatial and temporal distributions are examined and discussed. The results show the reference evapotranspiration and pan evaporation have similar regional distribution patterns in the Taiwan area both with the highest values being in the southwestern region and the lowest values being in the central region. This distribution pattern provides valuable information for regional hydrological studies since it is a key parameter in regional water resources assessment and water management.

並列關鍵字

Reference evapotranspiration ； Penman-Monteith ； Pan coefficient