Comparison of Actual Evapotranspiration Amounts Estimated Using Water Balance and Eddy-Covariance Methods: Applications to Seolmacheon and Cheongmicheon Basins

In this study, actual evapotranspiration data estimated using the water balance and eddy-covariance methods were compared. Two different basins, i.e., the Seolmacheon and Cheongmicheon basins, were selected, and the actual evapotranspiration was observed using the eddy-covariance method. The rainfall, runoff depth, and actual evapotranspiration data between 2010 and 2018 were collected and analyzed. Daily evapotranspiration data and 10-minute rainfall and runoff data were then accumulated to analyze the annual data. The results showed that the annual actual evapotranspiration amount obtained using the eddy-covariance method was somewhat close to that using the water balance method. This result is interesting, as the monthly variation between the two methods was high. The difference between the actual monthly evapotranspiration and the total loss was not influenced by monthly temperature and rainfall. This tendency was the same throughout the year, but the variation increased during the summer rainy season. In conclusion, both the actual evapotranspiration data estimated using the water balance and eddy-covariance methods can be used as representative annual values for the basins, regardless of the difference between the two data sets.