基于温度的ET_(0)模型改进及在海河流域的适用性

Improvement and Applicability of Reference Crop Evapotranspiration Model Based on Temperature in Haihe River Basin

为提高HS模型估算海河流域参考作物蒸散量(ET_0)精度,基于贝叶斯原理,利用海河流域8个地理分区1980—1999年29个气象站的逐日气象数据对其温度指数、温度系数和温度常数进行改进,并以FAO Penman-Monteith(PM)模型为标准,利用1980—1999年和2000—2015年数据对HS改进模型适用性进行评价。海河流域HS改进模型的温度系数、温度常数和温度指数的范围分别为5×10^(-4)~8×10^(-4)、28.5~38.0和0.4~0.7。与PM模型计算结果对比,HS改进模型均方根误差(RMSE)下降,相对误差(RE)明显降低,1980—1999年RMSE由0.92下降到0.84,RE从-13%~3%降至-4%~1%,2000—2015年RMSE由1.00下降到0.96,RE从-18%~2%降至-16%~-1%。HS改进模型计算结果与PM计算结果的时空变化一致,具有较高的计算精度和较好的适应性。HS改进模型有助于提高海河流域缺少风速、辐射等气象资料条件下ET_0估算精度,可为海河流域ET_(0)简化计算、作物需水量计算及灌溉制度的确立提供参考。

In order to improve the accuracy of reference crop evapotranspiration(ET0)calculation with HargreavesSamani(HS)model,based on the Bayesian principle and the daily weather data of 29 meteorological stations in the eight geographical divisions of Haihe River basin from 1980 to 1999,this paper improved the temperature exponent(C),temperature coefficient(a)and temperature constant(m)of HS model.Furthermore,the FAO PenmanMonteith(PM)Model was regarded as the evaluation standard to estimate accuracy and adaptability of the improved HS model,data from 2000 to 2015 were used for model adaptability verification.The results show that the range of C,a and m coefficients are 5×10^(-4)-8×10^(-4),28.5-38 and 0.4-0.7 respectively.The absolute deviation,relative deviation and relative error of the improved HS model ET0 were significantly reduced,the relative error(RE)and the root mean square error(RMSE)of between the improved HS model ET0 and the PM model ET0 were reduced from-13%-3%to-4%-1%,0.92 to 0.84 during 1980-1999,from-18%-2%to-16%-1%,1 to 0.96 during 2000-2015.The spatial and temporal variation analysis shows that the improved HS model ET0 is basically consistent with the PM model ET0 and shows less difference.The study result will help to improve the estimation accuracy of ET0 in different climatic regions under limited meteorological data(without wind speed and radiation).The improved HS model can be used as a simplified recommended model for calculation of reference crop evapotranspiration in Haihe River basin,which provides a simple method for the determination of crop water demand and establishment of irrigation schedule in the area.