Estimating groundwater evapotranspiration by phreatophytes using combined water level and soil moisture observations

다국어 초록 (Multilingual Abstract)

One of the classical methods for estimating groundwater evapotranspiration (ETg) by phreatophytes is based on diurnal water table fluctuations (WTFs). This method was initially introduced by White in 1932 and has recently been improved. However, vegetation‐induced disequilibrium between groundwater and capillary fringe (CF) water is not considered under White's assumptions. In this study, we propose an approach that considers root‐driven water depletion in the CF using the soil moisture profile (hereafter referred to as the SMP method). The SMP method is demonstrated to perform equally well for both long‐term water table rises and declines. The apparent advantages of the SMP method over traditional WTF‐based methods include its greater effectiveness in revealing physical mechanisms and its omission of specific yield determination. However, appropriately determining the boundary condition, which is related to active root‐zone thickness, is crucial for the SMP method. Further development of the SMP method requires a deeper understanding of the interactions among roots, groundwater, and soil moisture.