甘肃地区参考作物蒸散量时空变化研究

区域水土平衡模型的建立通常需要确定计算参考作物蒸散量的模型,这一模型的精确与否,直接影响整体预测模型的最终预报精度.运用FAO-24 Blaney-Criddle法、FAO-24 Radiation法、FAO PPP-17 Penman法及FAO Penman-Monteith(98) 4种方法,对甘肃省1981～2000年33个站点的月参考作物蒸散量进行了计算.对比分析结果表明,AO Penman-Monteith(98)模型的精度与灵敏度均显示了较强的优越性.运用该模型对甘肃省参考作物蒸散量的时空分布特征进行研究表明:甘肃省参考作物蒸散量年内逐月演变曲线呈单峰状;年际蒸散量变化与夏季年际波动变化存在较高一致性;全年参考作物蒸散量分布具有从东南向西北递增的趋势.

Temporal-spatial changing characteristics of reference crop evapotranspiration in Gansu Province

It is important to estimate reference crop evapotranspiration precisely in the process of regional water resources and land use balance evaluation. Some methods for estimating reference crop evapotranspiration were validated, which include FAO-24 Blaney-Criddle method, FAO-24 Radiation method, FAO PPP-17 Penman method and FAO Penman-Monteith(98) method. Analysis of the correlation between the calculated reference crop ET with the evaporation measured by 20 cm pan, FAO Penman-Monteith(98) performed the best, with R² value equaling 0.89, whereas values of R² for FAO PPP-17 Penman, FAO-24 Blaney-Criddle and FAO-24 Radiation was 0.88, 0.87, 0.84 respectively. Sensitivity analysis of these models showed that FAO Penman-Monteith(98) model and FAO PPP-17 Penman method were better in performance, while FAO-24 Blaney-Criddle method and FAO-24 Radiation method were worse. Further more, FAO Penman-Monteith(98) model was applied to calculate reference crop evapotranspiration in Gansu Province from 1981 to 2000 year. The results showed that the highest E_TP of multi-year monthly average was in July, and the variation of annual reference crop E_TP was consistent with the evapotranspiration variation of summer season, further more ET was the highest in southeast and the lowest in northwest.