Effect Of Climate Change On Water Requirement Of Winter Wheat In North China Plain

In order to tackle climate change and improve the spatial-temporal collocation of water resources,the localization management was performed for the parameters of the Hargreaves model with reference evapotranspiration?ET₀?,which was calculated with the Penman-Monteith model using the daily meteorological data from 88 weather stations in North China Plain during 1961-2010.The long series of daily temperature,radiation,rainfall data from 2010 to 2100 in representative concentration paths RCP4.5 and RCP8.5 scenarios were simulated with the statistical downscaling model?SDSM4.2?and the second generation of Canadian Earth System Model?CanESM2?.Then the potential yield,potential evapotranspiration and required irrigation water of winter wheat were simulated by DSSAT-CERES-Wheat model,which was calibrated with fitting Hargreaves formula and dynamic crop coefficient.The main results were as follows:?1?The annual dynamics of the transformation coefficient K of the Hargreaves model was similar with the variation of K in summer.The K value increased gradually from the northwest to southeast in the North China Plain.However,the K value in spring,autumn and winter was opposite to the variation in summer,decreasing gradually from the northwest to southeast in this region.Changes in the exponential coefficient n in the scale of year and summer were similar,which increasing from the southeast to northwest in the North China Plain gradually.The values of temperature offset T_off increased gradually from the southwest to northeast in this region.T_off increased gradually from the south to the north in the scale of year,spring,summer and autumn.While in winter,T_off increased gradually from the west to the east.The correlation index between the calibrated Hargreaves model and PM model was 0.79 in the scale of year,0.70 and 0.71 in spring and autumn,and 0.46 in winter.?2?The minimum and maximum temperature and rainfall under the 2 climate scenarios all had a trend of increasing in the future,and the growth rate of them under RCP8.5 was much greater than that under RCP4.5.The solar radiation in the benchmark period had a trend of decreasing,then it reduced first and then increased under RCP4.5,with a trend of decreasing at last.However,the change of solar radiation under RCP8.5 was different,it induced first and then decreased,with a trend of increasing at last.?3?ET₀ in the north China Plain in 21st century under the 2 climate scenarios all had a trend of increasing in the future.ET₀ in the the north China Plain under RCP4.5 decreased gradually in a spoon-like curve from the border of Hebei,Shandong and Henan to the surrounding areas,and the minimum was observed in Tangshan and Laoting in Hebei,Dongtai in Jiangsu,and Zhumadian in Henan.The spatial distribution of ET₀ under RCP8.5 in 2020 s was very similar to that in 2050 s,ET₀decreased gradually from the border of Hebei,Shandong and Henan to the surrounding areas,and the minimum was observed in Tangshan and Laoting in Hebei,Dongtai in Jiangsu,and Zhumadian in Henan.But there was a great difference in the spatial distribution of ET₀ in 2080 s,especially for the spatial distribution of the greatest values.The maximum values were distributed in these areas in the north China Plain:Huimin in Shandong,Xinxiang in Henan,Bengbu in Anhui and Xuyi in Jiangsu.?4?The spatial distribution of the potential yield of winter wheat under RCP4.5 and RCP8.5 in2020s?2050s?2080s were similar,increasing gradually from the inland northwest to southeastern coastal in this region,as time went on,it showed belt distribution.The spatial distribution of ET_c under RCP4.5 and RCP8.5 in 2020s?2050s?2080s were also similar,it decreased gradually from the Shandong Peninsula and the center of Henan to the surrounding areas,and the minimum was observed in the northeast and central of Hebei,the border of southern henan and Anhui,and the southeast of Jiangsu.?5?The potential yield and water requirements of winter wheat and effective rainfall increased during the 3 time periods under RCP4.5,while irrigation amount decreased.The potential yield and water requirements of winter wheat and irrigation amount increased at first and then decreased during the 3 time periods under RCP8.5,however,the effective rainfall decreased at first and then increased.