Adjustment of Hargreaves equation by replacing land surface temperature instead of air temperature for estimating reference crop evapotranspiration

Document Type : Complete scientific research article

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Graduate Master Science student

Abstract

Reference crop evapotranspiration (ET0) data are desirable for assessing crop water requirements and scheduling farm irrigation. A large number of methods have been developed for assessing ET0 from meteorological data. In several places of the world including iran, the existing network of weather stations is insufficient to capture the spatial heterogeneity of this variable. The purpose of this study is to adjust the Hargreaves equation (HG) for using land surface temperature (Ts) data instead of air temperature to estimate ET0 only on the basis of the remote sensing-based surface temperature. For this purpose, a total of 365 images of MODIS Ts product for the years 2006 and 2007, covering irrigated sugarcane farms in Khuzestan were used. The results show that HG equation adjusted by both types of input data (land surface temperature and air temperature) has the same accuracy. RMSE and R2 were estimated 1.5 mm d-1 and 0.79, respectively.

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