The QWaterModel plugin provides an easy way to calculate evapotranspiration from land surface temperature (LST) maps in QGIS3. It is based on the simple, one-source energy balance model DATTUTDUT by Timmermans et al. ( 2015) and can be used with a wide range of thermal maps from various sources including satellites, drones/UAVs and handheld thermal cameras.

I created a tutorial to guide you through the whole workflow from thermal image, to application of the energy balance model to the final evapotranspiration estimate.