Short-term forecasting of daily crop evapotranspiration using the 'K-c-ETo' approach and public weather forecasts

摘要

Short-term forecasting of daily crop evapotranspiration (ETc) is essential for real-time irrigation management. This study proposed a methodology to forecast short-term daily ETc using the K-c-ETo' approach and public weather forecasts. Daily reference evapotranspiration (ETo) forecasts were obtained using a locally calibrated version of the Hargreaves-Samani (HS) model and temperature forecasts, while the crop coefficient (K-c) was estimated from observed daily ETo and ETc. The methodology was evaluated by comparing the daily ETc forecasts with measured ETc values from a field irrigation experiment during 2012-2014 in Yongkang Irrigation Experimental Station, China. The overall average of the statistical indices was in the range of 0.96-1.27mm d(-1) for the mean absolute error (MAE), 1.53-2.55mm d(-1) for the mean square error (MSE), 1.77-2.30mm d(-1) for the normalized mean square error (NMSE), 27.5-29.4% for the mean relative error (MRE), 0.71-0.44 for the correlation coefficient (R) and 0.46-0.05 for the mean square error skill score (MSESS). Sources of error werewere K-c estion, temperature forecasts and HS model that does not consider wind speed and humidity, and.the largesourceof error is K-c determination, which suggested that care should be taken when forecasting ETc with estimated K-c values in the study area.