Response Of Winter Wheat Drought To Meteorological Drought Above The Bengbu Sluice In The Huaihe River

In the background of climate change,drought disasters occur frequently.Agricultural production is directly affected by drought,and agricultural economic losses caused by drought each year are severe.Precipitation during the growth of winter wheat in the Huaihe River basin generally failed to meet its growth requirements and had an important adverse impact on winter wheat yield.Given the current precipitation data records,it is relatively easy to assess meteorological droughts.Therefore,investigating the lag time of winter wheat drought on meteorological drought provides an alternative method for monitoring and predicting winter wheat drought.This study takes the upper reaches of the Huaihe River Basin as the study area,based on the daily-scale meteorological data of 60 stations in the region,the crop water deficit index(CWDI)and the relative moisture index(M)were used to characterize the winter wheat drought and meteorological drought.Firstly,the temporal and spatial evolution characteristics of the two droughts were analyzed.Then the lag time of the winter wheat drought to meteorological drought was calculated,the main drought events were identified,the drought duration and drought intensity were extracted,and the recurrence period of winter wheat drought and meteorological drought was analyzed.The main factors affecting the lag of meteorological drought in winter wheat drought were discussed.The main research conclusions are as follows:(1)For the relative wetness index(M),there is no obvious change trend in the inter-annual growth period of winter wheat.In the 1980 s,the growth period before winter was above the drought;in the 1990 s,the filling was mature.During the period of drought,the drought condition was the lightest;for the winter wheat water deficit index(CWDI),except for the mature stage of grain filling,the CWDI in the other growth stages showed a slight downward trend.The winter wheat drought has a short period and a rapid change in the growth period before winter,but has a long and stable period in the rest of the growth period.The meteorological drought has a shorter period than the winter period.(2)The proportions of drought and above in CWDI and M sites are characterized by decreasing from the north to the south.There are very few sites that pass the sig-nificant test during the four growth periods of winter wheat,indicating that the two droughts do not change obvious.(3)The correlation coefficient of the four stages of winter wheat growth period was greater than 0.7,and the correlation of the maturity stage was the best,reaching 0.83,especially in 1975-2000.The CWDI and M cross-wavelet aggregation values of the mature stage of grain filling almost passed.A significant test of 0.05.The drought of winter wheat has hysteresis for meteorological drought and the lag time of each growth period is inconsistent.The lag time of the heading period is the shortest,which is 3.21d;the lag time of the wintering period is the longest,which is 84.35 d.(4)The response relationship between meteorological drought and winter wheat drought duration and intensity determined by the three-parameter logarithmic function model is reasonable.When the meteorological drought lasts 1.28,it will cause winter wheat drought,and the meteorological drought intensity is 3.35.The winter wheat drought duration is always greater than the meteorological drought recurrence period.(5)The lag time of the winter wheat drought on meteorological drought shows different fluctuations with the change of geographical factors.The correlation between the geographical factors of each growth period and the drought lag of winter wheat is good,both above 0.5.The high-value points of each geographical factor and the drought-time lag of winter wheat are mostly distributed in the mountainous areas with poor soil water holding capacity,high altitude and steep slope,and areas with east and northeast slopes with less precipitation and lower temperature.