Comparative study of evapotranspiration from the SWAT model and MODIS-derived remote-sensing data in two climatic zones in Egypt

Evapotranspiration (ET) estimation is highly dependent on several input factors that differ between different estimation methods either from models or remote-sensing data. Therefore, the main objectives of this study are to assess and compare the ET simulated from the SWAT model and derived from MODIS (SSEBop and MOD16A2) in South-Delta (northern Egypt) and KomOmbo (southern Egypt) zones during the period from April 2013 to December 2020. The daily rainfall, maximum temperature (Tmax), minimum temperature (Tmin), solar radiation (Rs), relative humidity (RH), and wind speed (WND) from the NASA-POWER agroclimatology dataset were used to run the SWAT model. The results showed that the simulated monthly, seasonal, and annual ET from SWAT is lower than SSEBop by about −41% in South-Delta and −66% in KomOmbo and higher than MOD16A2 by about 34% in South-Delta and 28% in KomOmbo. The SWAT model may have the potential to produce reasonable ET values, as it is reliant on both climatic and actual land-surface conditions. The monthly and seasonal ET from SWAT and MODIS is positively correlated with Rs, Tmax, Tmin, and WND, and is negatively correlated with RH and rainfall, while the annual ET has varied (positive/negative) weak correlation with the weather variables.