Research On The Relative Contribution Of Precipitation And Temperature To Agricultural Drought In The Growing Season Of Summer Maize In The Haihe Plain

In order to clarify the key issue of the relative contribution of precipitation and temperature in the formation of agricultural drought during the summer maize growing season,the spatial and temporal distribution of meteorological drought,high temperature events and concurrent events in the summer maize growing season from 1960 to 2019 in the Haihe Plain was used to simulate day-by-day agricultural drought data using the VIC(Variable Infiltration Capacity Model)model.Soil moisture data were used to study the characteristics of agricultural drought changes during the summer maize growing season based on simulated soil moisture,and precipitation invariance scenarios and temperature invariance scenarios were constructed in the VIC model to strip the role of precipitation and temperature in the formation of agricultural drought.The main conclusions are as follows:(1)The interannual variation of the range of meteorological drought occurrence,the number of high temperature events and the range of concurrent events of different intensities during the whole growth period,the jointing-flowering period and the flowering-maturity period of summer maize in the Haihe Plain in the last 60 years showed an overall trend of significant aggravation;among the three main periods,the number of high temperature events and the range of concurrent events were the most serious in the sowing-jointing period;the spatial distribution of meteorological drought occurrence in each period of summer maize in the last 60 years.The spatial distribution of drought frequency decreased from the west to the east,and the spatial distribution of high temperature events and concurrent events decreases from southwest to the northeast of the study area;The frequency of meteorological droughts,the number of high temperature events and the frequency of concurrent events increased significantly in the latter three decades(1990-2019)compared to the first three decades(1960-1989),with the most pronounced increase in the flowering-maturity period.(2)The VIC hydrological model could better simulate local soil moisture data after parameter calibration using Rosenbrock method,and the simulated values of soil moisture were in good agreement with the measured values in time and space.The inter-annual variation of soil moisture in summer maize during the whole growth period,jointing-flowering period and flowering-maturity period had a significant decreasing trend,the trend of local aridity was obvious.The frequency of agricultural drought in each period in the past 60 years was significantly aggravated;the occurrence of agricultural drought in the whole growth period,jointing-flowering and flowering-maturity periods also had a significant expanding trend,and the occurrence of agricultural drought in the three main periods was the most extensive in the sowing-flowering period.The frequency of agricultural drought in the last 60 years decreased from the western to the eastern.The frequency of agricultural droughts increased significantly in the latter three decades(1990-2019)compared to the first three decades(1960-1989),with the most pronounced increase in the flowering-maturity period.(3)The contribution of precipitation and temperature to agricultural drought both increased significantly during the whole growth period of summer maize,and the trend of precipitation contribution to agricultural drought was much higher than that of temperature,but since 1996,the rate of change of temperature contribution to agricultural drought was much higher than that of precipitation;the contribution of precipitation to agricultural drought showed a decreasing trend from the southwest to the northeast of the study area,and the contribution of temperature to agricultural drought showed a decreasing trend from the southeast to the northwest of the study area.The relative contribution of precipitation to agricultural drought was 96%,and the relative contribution of temperature was 4%;the relative contribution of temperature to agricultural drought gradually decreased and the relative contribution of precipitation gradually increased as agricultural drought increased.