| As an important natural resource in the development of ecosystems and social economic systems,water resources are of great significance to the protection and sustainable development of water resources to ensure the efficient use of water resources in human production and life.As the main grain production area in my country,the Yangtze River Economic Belt has six major commercial grain production bases in the region,and agricultural water accounts for more than 50%of the regional water supply.However,in recent years,with the uneven distribution of water resources,weak water management,and increasingly serious water pollution problems,water shortages have severely restricted the sustainable development of regional agriculture.Exploring the temporal and spatial evolution of the water footprint of crop production in the Yangtze River Economic Zone and evaluating the efficiency of regional agricultural water use can provide an important basis for the efficient development of agriculture in the Yangtze River Economic Zone,the rational use of water resources,and the protection of regional food security and water environment safety.The main results are as follows:(1)The water footprint of crops in the Yangtze River Economic Zone showed a slight upward trend after declining fluctuations.The total green water footprint was the largest.The water consumed during the growth cycle of crops was mainly natural precipitation.Among the crops,the green water accounted for the largest proportion of the water footprint of rice production at 51.48%,while the blue water accounted for the largest proportion of the water footprint of wheat and corn production at 41.64%and 42.15%,respectively.In contrast,the production of wheat and corn is more dependent on irrigation water,and the production of rice is more dependent on natural precipitation.(2)The distribution of water footprint of crop production in the upper,middle and lower reaches of the Yangtze River Economic Belt is significantly different,and the overall distribution pattern is higher in the middle reaches and lower in the upper and lower reaches.The water footprint center of the Yangtze River Economic Zone is moving towards the middle and lower reaches as a whole.The development of agricultural production in the Yangtze River Economic Zone should pay attention to the selection of stress-resistant varieties according to local conditions in the middle and lower reaches of the Yangtze River Economic Belt to improve the level of agricultural mechanization and ensure food production.(3)The water use efficiency of rice in the three crops from 2008 to 2017 was relatively high and showed a trend of increasing year by year.In 2008,2012 and 2017,the water use efficiency of rice was 1.61 kg/m3,1.66 kg/m3 and 1.84 kg/m3 respectively;the next was maize,which changed more during the study period.Stable at 1.55 kg/m3;wheat water use efficiency is the lowest,showing a slight increase trend,with an average value of 1.16 kg/m3.The water use efficiency of various crops in the upstream and downstream areas is improving year by year,and the middle reaches of the region should pay attention to improving its water use efficiency while ensuring large-scale production.(4)The overall food security level and water environment security level of the Yangtze River Economic Zone are improving.The middle reaches of the region have the highest level of agricultural development.Most cities can guarantee food security and water environment security at the same time;water environment security issues exist in both the upstream and downstream regions,and should be based on Local natural conditions optimize planting varieties,and real-time monitoring of on-demand fertilization to ensure water environment security;in addition,upstream areas should also plan for grain planting areas in the region,and planting cash crops must also ensure that food crops are grown to ensure regional food security. |
