| Global warming is exacerbating the world’s water crisis.Agriculture is a major waterusing sector,and climate change will have a strong impact on future agricultural water use.As an important grain-producing region in my country,the Huang-Huai-Hai region has a large population density but low per capita water resources,and large seasonal fluctuations in precipitation,so it is necessary to make reasonable planning for its future agricultural water use.In order to alleviate the adverse effects of future climate change on agricultural water use in the Huang-Huai-Hai region,it is of great significance to study the impact of future climate change on the irrigation water use in this region.In this study,three crops including two kinds of main food crops(winter wheat and summer maize)and industrial crop-cotton were selected as the research objects,and the AquaCrop crop model was applied as a calculating and evaluating tool for future crop water requirement.The study also evaluates the future changes of irrigation water requirement under climate change,irrigation water use coefficient,and plantation structure changes,which is expected to guide agricultural production and scientific management of agricultural water resources.Research results are as follows:(1)The temporal and spatial evolution characteristics of main meteorological factors in the Huang-Huai-Hai region under the future(2030-2089)climate scenario were evaluated.The temperature of the Huang-Huai-Hai region showed a significant upward trend under both the RCP 4.5 and RCP 8.5 climate scenarios,and the increase trend was more obvious under the RCP 8.5 scenario.The spatial distribution of precipitation showed a pattern of high in the south and low in the north.Under the RCP 4.5 scenario,the total annual precipitation in the study area showed an overall upward trend.Under the RCP 8.5 climate scenario,the upward trend in most areas of the study area was more obvious than that under the RCP 4.5 scenario.(2)The changes of crop water requirement and irrigation water requirement of three main crops at 89 sites in the Huang-Huai-Hai region in the future were evaluated.Under the historical scenario(1997-2015),the value ranges of crop water requirements for three main crops in the Huang-Huai-Hai region were cotton(560-820mm),winter wheat(400-700mm)and summer maize(400-600mm);irrigation The range of crop water requirement at each site is winter wheat(150-650mm),cotton(100-490mm)and summer maize(0-450mm).From2030 to 2089,the crop water requirements of the three crops under the RCP4.5 and RCP 8.5scenarios all showed upward trends,and the crop water requirement of winter wheat changed more significantly under the RCP 8.5 scenario.Compared with the RCP 4.5 scenario,the value of irrigation water requirement of winter wheat under the RCP 8.5 scenario was smaller,but the magnitude of change with time was relatively large;The irrigation water requirement of summer maize in the summer with more rainfall during the growth period is relatively small;The difference in irrigation water requirement of cotton between the two scenarios was small,and the trend of change with time was not obvious.The differences in the irrigation water requirements and the spatial and temporal distribution of crop water requirements of the three crops were related to the differences in the effective precipitation and crop water requirements during the crop growth period.(3)The changes of total irrigation water demand in the study area under the future climate and planting structure change scenarios were analyzed and evaluated.Due to the differences in water requirement characteristics of different crops,changes in regional planting structure would affect the total regional irrigation water requirement.The gray forecast indicates that the planting areas of winter wheat,summer maize and cotton in the Huang-Huai-Hai region would decrease by 12.4%,increase by 18.9% and decrease by 6.8%,respectively,in the base year.Scenario analysis of climate and planting structure change showed that by 2080 s,the change of planting structure under the RCP 4.5 scenario would reduce the total irrigation water requirement by 6.6%;under the RCP 8.5 scenario,the change in the planting structure would reduce the total irrigation water demand by 6.4%.The rational adjustment of planting structure would help reduce the total irrigation water requirement in the future climate change scenarios in the Huang-Huai-Hai region. |
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