- 學位論文
屏東麓山地區莿竹林蒸發散量之估測研究
Study on the Evapotranspiration Estimation for Thorny Bamboo Forest in Pingtung Piedmont of Southern Taiwan
摘要
本研究於屏東麓山地區利用21 m 高度之觀測鐵塔針對莿竹林地進行全天日射量、淨輻射量、氣溫、相對濕度、及地中傳導熱量等微氣象觀測，先經整理分析以了解其間微氣候特性，再選定莿竹林冠層與空曠地表分別進行竹叢與土壤採樣，以推求蒸散量與蒸發量，再配合覆蓋率估算。莿竹實際蒸散量，並採用自由水面蒸發量與利用彭曼改良法估算蒸發散量潛勢，進行相關性分析，藉以驗證莿竹林蒸發散量之合理性，及建立莿竹作物係數，另利用熱收支法推求及檢驗莿竹蒸發散量估值，期能對於莿竹林涵養水資源等研究參考。並建立莿竹林相關蒸發散經驗公式，觀測時間自2009 年7 月至2011 年05 月止。獲致研究結果：莿竹林餘土層深度0.5 m處之地溫變化幅度約0.4 ℃，在寒潮過境時之莿竹林近地表土層最低地溫仍能維持於15 ℃以上，且鬱閉莿竹林內水汽不易流動，會使相對濕度多維持75 %以上。莿竹林蒸發散量於春、夏、秋及冬季之日平均值分別為2.7、3.2、2.3及1.3 mm，而莿竹林於春、夏、秋及冬各季之作物係數分別為0.77、0.98、0.8及0.53。
並列摘要
This study was mainly aimed microclimate properties of the thorny bamboo plantation in the piedmont of Pingtung area. All the micrometeorological observations include as global solar radiation, net radiation, air temperature, earth temperature, relative humidity and soil heat flux were observed at the 21 m height from July 2009 to May 2011. To sampling canopy and ground on open place in thorny bamboo plantation could be estimated the transpiration and evaporation, then could be calculated by the cover rate of canopy. The correlation analysis of evapotranspiration with evaporation in free water and potential evapotranspiration by Penman modified method could test the reasonability in crop coefficient of the thorny bamboo plantation. The estimated evapotranspiration by heat budget method should be verified to establish a practical equation. All the performance of this study could provide reference to the study of water resources conservation in the thorny bamboo plantation. The results summarized as follow; the changing range of earth temperature was about to 0.4 ℃ with the soil layer in 0.5 m depth. The earth temperature could maintain more than 15℃ for the cold wave through. The dense canopy of thorny bamboo plantation resulted the moisture circulates of air layer to decrease, and the relative humidity was more than 75 %. The daily mean evapotranspiration of thorny bamboo plantation were 2.7、3.2、2.3 and 1.3 mm in Spring, Summer, Autumn and Winter, respectively. The crop coefficient of thorny bamboo plantation were 0.77、0.98、0.8 and 0.53 in Spring, Summer, Autumn and Winter, respectively.