CERES-Wheat模型中两种蒸发蒸腾量估算方法比较研究

Comparison of Two Crop Evapotranspiration Calculating Approaches in CSM-CERES-Wheat Model

基于CSM-CERES-Wheat模型中Priestley-Taylor（PT）和FAO56 Penman-Monteith（PM）2种蒸发蒸腾量估算方法分别模拟了冬小麦2011—2012年和2012—2013年2个生长季的累积蒸发蒸腾量、日蒸发蒸腾量、土壤含水率、地上干物质以及籽粒产量,并对2种方法的模拟结果进行了评价和比较。对2种方法模拟的蒸发蒸腾量值与试验区域内大型称量式蒸渗仪的实测结果进行了比较,结果表明,基于PT和PM方法的CERES-Wheat模型均可以准确地模拟干旱-半干旱地区冬小麦的蒸发蒸腾量,累积蒸发蒸腾量和日蒸发蒸腾量的误差分别小于5.4%和3.4%。同时,模型还可以模拟土壤水分动态情况,在0~20 cm土层,CERES-Wheat模型的模拟值与实测值的标准化均方根误差（RRMSEn）为39.38%,模拟结果较差,但20 cm土层以下,2种方法的模拟值与实测值的RRMSEn均小于23.1%,且对40~60 cm土层的模拟结果最好。CERES-Wheat模型基于PT和PM方法对冬小麦在2011—2012年和2012—2013年生长季地上生物量的模拟值与实测值的RRMSEn分别为13.57%和22.76%,产量的RRMSEn分别为11.80%和15.42%,模拟结果均较好。另外,CSM-CERES-Wheat模型基于PT方法模拟的蒸发蒸腾量小于基于PM方法的模拟值,而PT方法对土壤含水率的模拟结果高于PM方法的模拟结果,且PT方法对地上生物量以及产量的模拟结果高于PM方法,用2种方法模拟的成熟期地上生物量及产量的RRMSEn值均在25%以内。总之,CSM-CERES-Wheat模型采用2种方法对蒸发蒸腾量、土壤含水率及干物质和产量的模拟结果均较好,表明该模型在我国干旱-半干旱地区的应用性较好,可为该地区不同水分条件下冬小麦的生长情况提供理论支持。

Crop water requirement is one of the most important factors in farmland water circulatory system,its accurate estimates could help with crop irrigation management. The ability of simulating evapotranspiration（ ET） for CSM-CERES-Wheat model is very important,which determines the accuracy of model output parameters. The objective was to evaluate the capability of CSM-CERES-Wheat model to simulate the cumulative evapotranspiration,daily evapotranspiration and soil water content of winter wheat（ Triticum aestivum L.） in 2011—2012 and 2012—2013 growing seasons under semi-arid condition. The daily ET was measured by using weighing lysimeter that installed in the experimental plot. The ability of CSM-CERES-Wheat model by using two different ET calculating approaches,i. e.,Priestley-Taylor（ PT） and Penman-Monteith（ PM）,and the simulation results were evaluated and compared. Data were obtained from two experiments with three irrigation levels that were conducted under controlled condition in a rain-out shelter in Yanling,Shaanxi Province of China during the 2011—2012 and 2012—2013growing seasons. Results showed that the simulated cumulative ET,daily ET and soil water content of CSM-CERES-Wheat model with both PT and PM approaches had great agreement with measured values,and the simulated cumulative ET and daily ET were 5. 4% and 3. 4% less than those of observed values,respectively. The CSM-CERES-Wheat model simulated cumulative ET for winter wheat in two growing seasons through PT approach was less than that through PM approach,the relative difference between two approaches was ranged from-3. 11% to-0. 05%. The model could simulate soil water content correctly as well,in the depth of 0 ~ 20 cm soil layer,the RMSEn between simulated results based on two ET approaches and observed values was 39. 38%,which was relatively high and not good,but below the20 cm soil depth,the RMSEn between simulation results that based on two ET approaches and observed values was less than 23. 1%,and the simulation results in depth of 40 ~ 60 cm soil layer got the best agreement with the observed values. The model with both PT and PM approaches simulated the aboveground biomass and grain yield accurately as well. The RMSEn of final above-ground biomass for two growing seasons were 13. 57% for PT approach and 22. 76% for PM approach,and RMSEn of grain yield were 11. 80% for PT approach and 15. 42% for PM approach,both of the simulated results had good agreement with observed values. The model using PT approach provided smaller ET and higher soil water content than those derived from PM approach as compared with measured data. Additionally,the model using PT approach provided higher final above-ground biomass and grain yield than those derived from PM approach as compared with measured data. However,the model with both two approaches could simulate the total above-ground biomass and grain yield with RMSEn within 25% of measured data.Overall,it can be concluded that the CSM-CERES-Wheat model using the two different approaches,i.e.,PT and PM,was able to accurately simulate winter wheat ET and soil water content. The results also confirmed that the model could be applied in arid and semi-arid areas,and it can be used as a tool for agricultural water management and supplying the decision support for winter wheat growth in Guanzhong Plain.