蒸發散與降水入滲為影響陸表與大氣間重要的水交換機制，其變動特徵除受大氣條件影響外也與地表狀態有關。蒸發散與入滲透過植物根系與土壤水的傳輸也影響著地下水的收支，而在事件與季節性尺度下蒸發散與入滲如何快速或遞延影響地下水位的變動與其機制則更加複雜。本計畫延續前二年度規劃，提出二年期的研究規劃，以互補理論在草地與森林實際蒸發散量之跨時間尺度推估應用為研究主軸，包含在中大草地測站與蓮華池測站的觀測與驗證。在氣象坪實際蒸發散量推估，將以土壤含水量的損失估算，蒸發皿提供潛勢蒸發散量估算，輻射觀測提供Priestley and Taylor方程式計算平衡蒸發散；在蓮華池測站部分，將先進行EC通量缺補與能量平衡探討，以EC潛熱通量代表實際蒸發散量，以Penman 類型方程式推估潛勢蒸發散，以Priestley and Taylor方程式計算平衡蒸發散。時間尺度將涵蓋從小時、日、月與年等不同尺度的驗證應用，此外也將延續前二年度的研究規劃，在草地氣象坪持續進行以水平衡分析入滲與蒸發散與土壤含水量變動、變飽和地下水數值模式驗證，以及森林試驗集水區耦合陸表過程模式建置與驗證等工作。計畫成果預期釐清從事件到季節性尺度下蒸發散與降水入滲和土壤含水量與地下水位變動之動態連結關係，提供未來陸表過程模式或集水區水文模式在處理大氣水、地表水、土壤水與地下水間之交換機制與提供創新的水文科學知識與解決工具。 ;Evapotranspiration (ET) and rainfall infiltration are important water exchanges between land and atmosphere. Variations of ET and infiltrations are affected by both micrometeorology and wetness and dryness of surface conditions. Groundwater budget is conceptually dominated by ET and infiltration by root uptaking and downward moving of soil water, respectively. Interestingly, how fast or delayed responses of groundwater levels to these fluxes during event or seasonal scales and their interconnected mechanisms are furthermore complicated. Based on previous two years of studies, we proposed two-year of proposal to investigate applicability of complementary theory on estimating grassland and forest ET with different spatial scales. Over the grassland environments, losses of soil moistures will be used to estimate actual ET, pan evaporation will be used to represent potential ET, equilibrium ET will be estimated by the Priestley and Taylor equation. Over the forest environment, the eddy covariance latent fluxes will be sued to estimate actual ET, the Penman type equation will be used to estimate potential ET, and the Priestley and Taylor equation will be used to estimate equilibrium ET. Other tasks like water balance analysis on ET and rainfall infiltration and varied saturated subsurface simulations will be continued as we did for the previous projects for the grassland environment. For the forest environment, we will conduct land process simulations with filed observations for verification. The research will provide contributions to understand dynamic nexus of ET, infiltration, soil moisture and groundwater from event to seasonal scales. Novel scientific knowledge and solution tools of handling interactions among atmospheric water, surface water, soil water, and groundwater will be delivered to facilitate simulations of land surface process and watershed hydrology.
