A Comparative Analysis of Estimating Reference Evapotranspiration Models in Nguru, Nigeria

This present study estimates and compares six various universally accepted models for estimating reference evapotranspiration (ET₀) for Nguru situated in the Sahelian climatic zone of Nigeria using measured meteorological parameters of monthly mean daily global solar radiation, sunshine hour, wind speed, minimum and maximum temperatures and relative humidity covering a period of thirty one years (1988 – 2018). Four different statistical validation indices of Root Mean Square Error (RMSE), Mean Bias Error (MBE), Mean Absolute Error (MAE) and coefficient of correlation (R) were carried out to test the accuracy of the evaluated models. The result indicated that high values of ET_o were found in the month of April with 7.9670 mm/day for Nguru, and low values were found to be in August with 4.973 mm/day for Nguru. The Blaney – Morin Nigeria model was found more accurate for estimating evapotranspiration for Nguru with RMSE, MBE, MAE and R values as 0.8561 mm/day, -0.2927 mm/day, 0.2927 mm/day and 0.9162 respectively.