Comparison and Correction of Calculation Methods of Reference Crop Evapotranspiration in Luzhou City

In order to obtain accurate calculation results of reference crop evapotranspiration（ET0）in the areas with missing meteorological data，and to explore applicability of ET0 simple methods in Luzhou City，Penman-Monteith（PM）method was employed as standard method to compare ET0 calculated by simple methods including Hargreaves（Har）method，FAO24 Blaney-Criddle（FAO24 BC）method，Makkink（Mak）method and Priestley-Taylor（PT）method.The linear relationship and Bayesian formula were used to correct each method.Through error analysis，it was concluded that Har and PT methods had good performances with relatively small errors in study area.The RMSE was 0.5~1.1 mm/d and PE was 10%~15%，correction of linear relationship was better than the Bayesian formula.After linear correction，error of the Har and PT methods was reduced by about 50% and 80%，respectively.It could be obtained that correction effect of PT method was much better than the Har method.Therefore，PT method corrected by linear relationship was more suitable to replace PM method to calculate ET0 when meteorological data was missing，and it could provide theoretical basis and data support for estimating crop water requirements in the future.