Analyses, calibration and validation of evapotranspiration models to predict grass-reference evapotranspiration in the Senegal river delta

Abstract

Study region: Grass-reference evapotranspiration estimation by the Penman-Monteith method (PM-ETo) requires a number of climate variables which are not always available at all weather stations. Different alternative ETo equations have been developed and their utilization for various local climate conditions requires analyses of their accuracy as compared to the standardized Penman-Monteith method. There is a significant lack of data and information on this topic in the Senegal River Delta (SRD). Study focus: The objective of this study was to evaluate, calibrate and validate six ETo equations ((Trabert, Mahringer, Penman1948, Albrecht, Valiantzas1 and Valiantzas2) for the SRD. Although all six equations showed good agreement with the PM-ETo (R2 > 0.60) for daily ETo estimates, the Valiantzas2 equation was the best model for the Senegal River Delta and had the lowest root mean squared difference (RMSE) of 0.45 mm/day and the lowest percent error of estimate (PE) about 7.1%. New hydrological insights for the region: In the case of data limitations, the equations calibrated in this study are recommended for ETo estimation in the Senegal River Delta. The results of this study could be used by agricultural producers, crop consultants, university researchers, policy makers for the agricultural, hydrological, and environmental studies as well as proper allocation and use and forecasting in the SRD where lowland irrigated rice is predominant