蒸發散量之估計，目前已發展出許多的方法，一般可大致分為五種類型：(1)彭門-蒙地斯組合法；(2)溫度估計法；(3)輻射能法；(4)質量傳遞法；(5)水平衡法等。若將上述方法應用於研究上，不同經驗公式具有其不同之適用性，部分公式需大量的基本資料及實驗，因適當條件而選定適當之方法進行推估。本研究以台灣地區為研究案例，探討不同理論基礎之潛勢能蒸發散經驗公式，與國際上廣泛應用之彭門-蒙地斯組合法作一比較，以建立本土化參數。本研究選用溫度估計法中的Blancy-Criddle 法、Hargreaves and Samani 法及Kharrufa 法；與輻射能法中的Makkink法、Priestley and Taylor 法及Hargreaves 法，應用於台灣地區之台北、台中、台南及台東等四個測站來分別探討現地參數之最佳化。 The purpose of this study is to apply the Penman-Monteith equation to estimate evapotranspiration occurred in Taiwan, an equation not only widely used in the world but also officially recommended by FAO. In addition, the Penman-Monteith equation is considerably more complex than other equations, which has been also used extensively in
water budget. In this study, various empirical equations from different theoretical models for calculating evapotranspiration are compared with the Penman-Monteith equation based on daily meteorological data from four meteorological stations in Taiwan. Monthly evapotranspiration was estimated using equations developed by Blancy Criddle (1950), Hargreaves-Samani (1985), Kharrufa (1985), Makkink (1957), Priestley-Taylor (1972), and Hargreaves (1975). Finally, three statistical criterions are used to establish the optimal parameter suitable to the local hydrological condition of Taiwan.
