Monitoring Evapotranspiration in Yenicaga Bolu from Landsat images in a trapezoidal framework

Evapotranspiration (ET), defined as the sum of soil evaporation and plant transpiration, is the second important term in hydrological water cycle. ET can be employed to balance the water and energy budgets in basins, monitor droughts and agricultural water consumption. The objective of this study is to estimate ET from Landsat 5 and Landsat 8 satellite products in a trapezoidal framework. The model first calculates the evaporative fraction (EF) and then ET using the net radiation (Rn) products. The model outputs were validated against the ground observations collected at an eddy covariance flux tower in Yenicaga, Bolu between 2010 and 2014. The results indicate that the model was able to estimate EF very accurately, and modeled EFs were highly correlated with the ground EFs. However, there was an underestimation of ET by the model because Rn products underestimated Rn values observed at the flux tower. In summary, since the model can produce EFs with small errors, it is possible to estimate ET accurately with different Rn datasets from space.