Spatio-temporal variation of evapotranspiration derived from multi-temporal landsat datasets using fao-56 penman-monteith method

Abstract

Reference evapotranspiration (ET0) is the representation of real-time crop-specific measurement of evapotranspiration and could be used for measuring the available water for agriculture. Accurate estimation of reference evapotranspiration (ET0) is required for irrigation management and water resource allocation. Satellite remote sensing provides an opportunity to estimate its quantity and map the spatio-temporal distribution of evapotranspiration in an efficient way. There are several methods developed for estimating ET0 but most of them are mainly based on daily meteorological data provided by weather station networks. This paper aims to estimate the monthly reference evapotranspiration (ET0) by the FAO-56 Penman-Monteith method using the remote sensing data (LANDSAT 8-OLI and LANDSAT 7-ETM+) of 2014, 2015, 2016 and weather data (Maximum and minimum temperature, Dew point temperature, wind speed, relative humidity) over the Dwarakeswar river basin. Input parameters required for this model are emissivity, land surface temperature (LST), net radiation, soil heat flux (G), air temperature, actual and saturation vapor pressure and wind speed. This study indicates that evapotranspiration variation in this area is closely related to crop growth. Evapotranspiration values were found low (66–120 mm/month) when paddy fields were empty and the fields were covered by very sparse vegetation. Whereas, the estimated values were high (120–180 mm/month) in cropping season and in monsoon, when vegetation cover was dense. Furthermore, the evapotranspiration estimation results were analyzed and validated with MODIS data which shows a good agreement between them.