Temporal And Spatial Evolution Characteristics Of Crop Production Agricultural Water Footprint And Sustainable Utilization Of Water Resources In The Sanjiang Plain

As an important main grain producing area in China,the Sanjiang Plain accounted for more than 5% of the national grain output in 2019.The sustainable development of agriculture in this area is related to China’s food security.However,with the development of social economy,the problem of water shortage is becoming more and more prominent,and the problem of water quality deterioration is also becoming more and more serious.The problem of water resources has gradually become the main factor restricting the sustainable development of agriculture and the high-quality social and economic development of the Sanjiang Plain.As a comprehensive indicator for evaluating the status of water resources consumption and pollution,water footprint has opened up a new way to evaluate the specific use of water resources in the process of agricultural production,and provided a new way of thinking for the sustainable utilization of agricultural water resources in the study area.Therefore,evaluating the sustainability of agricultural water resources in the Sanjiang Plain based on the water footprint theory is of great significance to deeply understand the status of agricultural water resources in the Sanjiang Plain and realize its efficient use of water resources.Based on the water footprint theory,this study calculates the water footprints(blue water,green water and grey water footprints)of major crops in the Sanjiang Plain from 2000 to 2019,and uses the M-K trend analysis method to test the time evolution law,and uses Arc Gis software to draw The spatial distribution map explor es the characteristics of spatial variation,and the spatial agglomeration of agricultural water footprint intensity based on the ESDA method.The improved LMDI model was used to explore the impact of water footprint structure effect,water footprint intensity effect,land output value effect,per capita land effect and population change effect on crop production water footprint,analyze the driving mechanism of agricultural water footprint in the Sanjiang Plain,and then based on the path analysis method The direct and indirect path coefficients of the influencing factors were analyzed,and the difference in the contribution rate of the influencing factors to the crop production water footprint was obtained by comparing the two different methods.Finally,the sustainability of the agricultural water resources in the Sanjiang Plain is evaluated by using the water footprint index to improve the sustainability evaluation index system.The main research contents and conclusions are as follows:(1)Structural characteristics and spatiotemporal evolution of agricultural footprints in the Sanjiang PlainAccording to the social economy,agricultural production and other data of the Sanjiang Plain,and based on the water footprint theory,the water footprint of the fo ur main crops(rice,corn,soybean and wheat)in the Sanjiang Plain from 2000 to 2019 was calculated,and the temporal and spatial evolution laws and regional structural characteristics were analyzed;Based on this,the intensity of agricultural water footprint in each region was quantified,and the spatial agglomeration and dispersion of agricultural water footprint intensity were explored with the help of GeoDa software.The research shows that: the green and grey water footprints of the Sanjiang Plain have an upward trend during the study period,and the blue water footprint has an obvious downward trend during the study period;the structural characteristics of water footprints in different regions are significantly different,with Shuangyashan City,Hegang City and Jixi City.The consumption of green water resources is high,and the average proportion of green water resources for many years is 46%,54% and48% respectively.The average proportion of grey water footprint in Qitaihe and Jiamusi cities is 56% and 45% respectively,higher than the other three cities;the spatial difference of agricultural water footprint in the Sanjiang Plain is obvious,and the overall trend is that the north is high and the south is low.;The agricultural water footprint intensity of the Sanjiang Plain showed a downward trend during the study period and finally stabilized,and there was no obvious agglomeration of the agricultural water footprint intensity in each region.(2)Research on the driving force of agricultural water footprint in the Sanjiang PlainThe improved log-average Diesel index decomposition model(LMDI)was used to decompose the agricultural water footprint driving force into water footprint structure effect,water footprint intensity effect,land output value effect,per capita land effect and population change effect.The contribution value was determined to determine the key factors affecting the change of agricultural water footprint in the Sanjiang Plain,and then compared with the results based on the path analysis method.The research shows that the comprehensive effect of crop production water footprint in the Sanjiang Plain generally presents a trend of first increasing and then decreasing,and the land output value effect and per capita land effect are the main positive driving factors.Water footprint structure and water footprint strength are the main negative drivers.From the path analysis,it is concluded that the per capita land effect,the land output value effect and the water footprint intensity effect have a greater impact on the agricultural water footprint.It can be seen that the influencing factors that directly affect the water footprint of crop production to a greater extent are social and economic factors.(3)Evaluation of Sustainable Utilization of Water Resources in Sanjiang PlainBased on the water footprint theory and the index of sustainable utilization of water resources,an evaluation system was constructed to evaluate the sustainability of agricultural water resources in the Sanjiang Plain from 2000 to 2019.The research shows that the dependence of the Sanjiang Plain on green water resources has increased significantly;from the perspective of benefit evaluation,the revenue created by the unit water footprint doubled during the study period;from the perspective of ecological security assessment,the water pressure of the Sanjiang Plain is ranked from low to high.It is Qitaihe City,Jiamusi City,Shuangyashan City,Jixi City and Hegang City,and the spatial distribution shows a trend of high in the north and low in the south;from the perspective of sustainability evaluation,during the study period,the agricultural water resources in the Sanjiang Plain were only in The years 2002,2009,2012,2013,2016,2018 and 2019 were in a sustainable state,while the agricultural water resources in the remaining years were all in an unsustainable state,and the sustainability of water resources was extremely unoptimistic.