Research On The Temporal And Spatial Relationship Between Water Supply And Demand And Irrigation System Of Corn In Heilongjiang Province Under Climate Change

Climate change will have a significant effect on crop water requirements(ET_c).The Spatiotemporal distribution of water requirement of maize under climate change are essential elements when conducting a global water security assessment,making irrigation schedule making the allocation of regional water resources more meaningful.Based on the daily meteorological data of 26 meteorological stations in Heilongjiang Province from 1960 to 2015,we used the single crop coefficient method to calculate the evapotranspiration(ET₀),ET_c,effective precipitation(P_e),crop water surplus deficit index(CWSDI),and irrigation water requirement(I_r)based on the CROPWAT model,and the temporal and spatial distribution map was drawn.The different hydrological years in Heilongjiang Province were determined by the hydrological frequency calculation,ET_c,P_e,CWSDI,and I_r in different hydrological years were calculated and the spatial distribution map was drawn,and then establishing irrigation system in Heilongjiang Province.(1)The results showed that the annual average ET₀,ET_c,P_e,and I_r of maize were552.97 mm,383.05 mm,264.97 mm,and 193.82 mm,respectively.(2)During the study period,ET₀,ET_c,P_e decreased by 3.28,2.56,and 6.25 mm per decade,respectively,while I_r increased by 1.63 mm per decade.The decline rate of ET_cis less than the P_e,which leads to the decrease of CWSDI.The ET₀,ET_c,and I_r in the study area decreased first and then increased from west to east,and the P_e and CWSDI increased first and then decreased from west to east.From 1960 to 2015,the water deficit in the western region was alleviated,and the water deficit in the eastern region was gradually severed.However,due to the large ET_c in the west region,the drought situation in this region still needs attention.(3)The calculation results of different hydrological years show that the ET_c of central and western regions and a few eastern regions are relatively large in Heilongjiang Procince,and the average I_r of maize in Heilongjiang Province is 171.14mm in a wet year,232.79 mm in a normal year,279.08 mm in dry year and 334.47 mm in extremely dry year.According to the I_r of four different hydrological years,Heilongjiang Province is divided into four irrigation zones,in which the irrigation quota of different hydrological year is 0?180 mm,20?240 mm,60?300 mm and 80?430mm respectively.Making irrigation schedules for different hydrological years in Heilongjiang Province can reasonably distribute agricultural water and optimize regional irrigation management.