Spatio-temporal calibration of Hargreaves–Samani model in the Northern Region of Nigeria

Abstract One of the significant components hydrological cycle is evapotranspiration. Monthly meteorological parameters 35 years from 19 stations across Northern Region Nigeria (NRN) were obtained and utilized for calibration Hargreaves–Samani (HS) model by comparing between potential evapotranspiration (ET o ) values estimated original HS Penman–Monteith (FAO-56 PM) models. The calibrated equation was assessed using trend patterns some statistical indices. average value root mean square error (RMSE) absolute (MAE) decreased 37.1 40%, respectively, after model. Also, correlation coefficients ( R that had > 0.8 increased 6 to 11 minimum 12% above equation. spatial map tests conducted also indicate better performance in most climatic regions calibration. precision improved significantly semi-arid, humid, sub-humid regions. However, few did not show drastic improvement due peculiarity location high variations wind speed relative humidity parameters.