| Haihe river basin is one of the most scarce areas in China.The efficient and sustainable utilization of agricultural water resources is an important way to alleviate the contradiction between the supply and demand of water resources in haihe river basin and to realize ecological protection and high-quality development of economy and society.Water footprint can be regarded as a comprehensive evaluation index of water resource occupation and is widely used in water resource management.The evaluation of sustainable utilization of agricultural water resources based on water footprint theory is of great significance for understanding the situation of agricultural water resources in haihe river basin and guiding the management of agricultural water resources.Of this study is based on historical meteorological data of 14 kinds of crops crop coefficient modification,on the basis of the haihe river basin in 1958-2017 main crop water footprint accounting,analyses the process of historical evolution,based on the theory of value of unit water footprint and water on crop water consumption structure,to optimize the adjustment of crop planting structure,based on water footprint,generalized water resources and water resources availability measures such as improving the water resources pressure index,and evaluate the sustainability of agricultural water resources of haihe river basin.The main research results are as follows:(1)based on the daily scale field water balance method,the footprints of blue water,green water and grey water of 14 crops in haihe river basin from 1958 to 2017 were calculated and their historical evolution characteristics were analyzed.The blue water footprint,green water footprint and gray water footprint of the haihe river basin account for 44%,40% and 16% of the agricultural water footprint of the river basin respectively,and irrigation water is the main source of agricultural water consumption in the haihe river basin.Food crops and cash crops account for 75% and 25% of the basin's agricultural water footprint,respectively.Winter wheat,summer corn,fruits and vegetables are the main water-consuming crops.The total water footprint of winter wheat,summer corn,sunflower,sugar beet,peanut,vegetable and fruit showed an upward trend,while the total water footprint of other crops showed a downward trend,indicating that the planting structure of major crops in haihe river basin had been adjusted.The blue water footprint of summer corn,sunflower,peanut,vegetable and fruit is on the rise,requiring more water for irrigation.There are significant regional differences in unit water footprint: the unit water footprint is the highest in Shanxi Province and the lowest in shandong province,which may be related to the highest proportion of rain-fed agriculture in Shanxi Province.Tianjin and Beijing produce the most blue water per unit of agricultural products.(2)based on the theory of unit water footprint and unit water value,water consumption types of major crops were divided.Cotton and sunflower are high water consumption and moderate water value crops.The unit water value of beet,vegetable and fruit is the highest,and the degree of water consumption is low,and the structure of water consumption is optimal.Sesame is a crop with high water consumption and unit water value.In order to optimize the agricultural planting structure and rationally utilize agricultural water resources in haihe river basin,the planting scale of cotton and sunflower can be further controlled,and the planting scale of vegetables and fruits can be appropriately expanded without causing the pressure of water resources.(3)the water resource pressure index was improved to evaluate the water resource pressure and its historical evolution characteristics in haihe river basin from 1998 to 2017.From 1998 to 2017,both the total water resource pressure index and the blue water resource pressure index of haihe river basin showed a downward trend,with an annual decline rate of 0.005 and 0.027,respectively.The water resource pressure index of henan province is on the rise,mainly because henan province is a big agricultural province,the water resource pressure is great.The pressure of water resources in other areas is decreasing,and the pressure of agricultural water resources is obviously relieved,especially in Beijing and tianjin.The water resource pressure in different regions is significantly different.The water resource pressure index of Shanxi Province and Beijing city is relatively low and abundant,while the water resource pressure index of shandong province is relatively high and the water resource is relatively tight,which can regulate the agricultural planting structure of shandong province.(4)the sustainability of agricultural water resources in haihe river basin from 1998 to 2017 was evaluated based on the evaluation system composed of water footprint growth index,available water resources growth index and sustainable water resources utilization index.From 1998 to 2017,the sustainable fluctuation of water resources in haihe river basin fluctuated between the two states of sustainability and unsustainability.In 1998,2000,2003,2007,2008,2010,2012,2015 and 2016,the water resources in haihe river basin are in a sustainable state.In other years,the water resources in haihe river basin are not sustainable.Among them,from 2001 to 2002,from 2004 to 2006,and from 2013 to 2014,the continuous water resources are not sustainable.The sustainability of water resources is not optimistic,and the conservation of water resources in haihe river basin is a long and arduous task. |
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