改进Hargreaves-Samani模型预测广西盆地参考作物蒸散量

Prediction of reference crop evapotranspiration in Guangxi Basin by improved Hargreaves-Samani model

准确估算参考作物蒸散量(ET_(0))对于区域水资源管理和灌溉决策有着重要意义.Hargreaves-Samani模型(HS)是目前公认结构最简单且精度较高的ET_(0)估算模型.为了进一步提高HS模型预测精度,采用蜂群理论和广西盆地20个气象站(1961—2019年)数据对HS模型全局校准,使用1961—2000年数据对HS模型进行校准,2001—2019年数据在日、月、年尺度上验证.结果表明:全局优化后的经验参数C,m和a中,参数a随地形起伏差异较大,而参数C和m差异较小;校准后HS模型(平均MAE和R^(2)分别为1.06 mm/d和0.86)优于原始HS模型(MAE和R^(2)分别为2.20 mm/d和0.68);在日、月和年时间尺度上,校准HS模型和原始HS模型都高估了ET_(0),但校准的HS模型与P-M模型计算的ET_(0)更为接近.因此,对仅有温度数据的地区,推荐采用校准的HS模型估算ET_(0).

Accurate estimation of reference crop evapotranspiration(ET_(0))is greatly significance for regional water resources management and irrigation decision-making.The Hargreaves-Samani model(HS)is currently recognized as the ET_(0) estimation model with the simplest structure and high accuracy.In order to further improve the prediction accuracy of the HS model,the bee colony theory and the data of 20 weather stations in Guangxi Basin(1961—2019)were used to calibrate the HS model glo-bally in this manuscript.The data of 1961—2000 were used to calibrate the HS model,and the data of 2001—2019 were verified on the daily,monthly,and annual scales.The results show that among the globally optimized empirical parameters C,m and a,the parameter a varies greatly with the topography,while the difference between the parameters C and m is small.The HS model after calibration(average MAE and R^(2) are 1.06 mm/d and 0.86)is better than the original HS model(MAE and R^(2) are 2.20 mm/d and 0.68).On the daily,monthly and annual time scales,both the ET_(0) calculated by the calibrated HS model is closer to that caculated by the PM model.Therefore,in areas only with tempe-rature data,it is recommended to use the calibrated HS model to estimate ET_(0).