| As a kind of natural resources and economic resources,water resources have an important impact on human production and life.At present,the scarcity of water resources and water pollution have seriously restricted regional economic and social development.However,most of the previous studies on water resource scarcity evaluation focused on arid areas with less precipitation.In fact,humid areas with abundant precipitation also face the problem of water resource scarcity and need to strengthen water resource management.Agricultural production plays a non-negligible role in social and economic development.As the largest water sector,agriculture cannot achieve sustainable development without water resources.Scientific and systematic quantification and evaluation of the current situation of water resources utilization in agricultural production,analysis of the scarcity of agricultural water resources,and setting up appropriate agricultural planting structure based on the utilization and scarcity of agricultural water resources.It can provide reference for regional agricultural water resources management,help to alleviate the contradiction between supply and demand of regional water resources,promote the coordinated development of regional water resources and economic development,and promote regional sustainable development.Based on the water footprint theory,this paper calculated the water footprint of major crops in Liuyang City,a typical agricultural area in Dongting Lake Basin,and constructed a three-dimensional agricultural water resource scarcity evaluation system on this basis.At the same time,aiming at the current agricultural water resources problems in the study area,based on the multi-objective optimization model,the planting structure of major crops in Liuyang City was optimized,and combined with the results of scarcity evaluation,the management suggestions of agricultural water resources in Liuyang City were put forward.The main conclusions are as follows:(1)From 2010 to 2019,the average annual total water footprint of crops in Liuyang City was 138,558 million m3,in which the blue water footprint,green water footprint and grey water footprint accounted for 30%,43%and 27%of the total water footprint,respectively.The water resources consumed by major crops in the production process were mainly from precipitation.In addition,the planting area of rape and tobacco with higher water footprint per unit yield is more reasonable and its water footprint is relatively low,while the planting area of vegetables with lower water footprint per unit yield is wider and its water footprint is relatively high.Regional agricultural crop planting structure is conducive to agricultural water resources security.The relationship between agricultural water footprint and economic growth in Liuyang City was mostly in a state of strong decoupling or weak decoupling.At present,economic growth and water resources consumption in Liuyang City were in a relatively good state.(2)During 2010-2019,agricultural water resources in Liuyang City had the problem of quantitative water scarcity.The blue water scarcity index(WSIbiue)exceeded the water shortage threshold because of the decrease of precipitation in dry years.From the perspective of green water scarcity index(WSIgreen),by comparing the monthly green water footprint with available green water resources,it is found that in most cases,the problem of green water scarcity would occur in May and June,and in some years,it would also occur in April and July.From the grey water scarcity index(WSIgrey),the grey water scarcity index during the study period did not exceed the threshold value,indicating that there was no water shortage problem of water quality.In addition,among the driving factors,natural meteorological conditions had the greatest influence on the three-dimensional agricultural water scarcity index,among which meteorological factors inhibited blue water scarcity index(WSIbiue)and grey water scarcity index(WSIgrey),and promoted green water scarcity index(WSIgreen).(3)After optimization based on the multi-objective optimization model,the crops with reduced planting area were middle rice,late rice and vegetables,among which middle rice had the largest reduction area.The crops with increased planting area were early rice,rape,tobacco and fruit,among which rape has increased the largest area.After the optimization of planting structure,the water resources benefit,environmental benefit and social and economic benefit of Liuyang City have been improved to some extent.By comparing the agricultural water resource scarcity index before and after optimization,it was found that the optimized agricultural blue water scarcity index,green water scarcity index and grey water scarcity index all decreased to different degrees compared with before optimization,indicating that the optimized planting structure could effectively relieve the regional agricultural water resource pressure.(4)In the future,Liuyang City can build a unified water resources management system and establish a red line of water footprint control from the perspective of water footprint.For the problems of engineering water scarcity and blue water scarcity in Liuyang City,the construction of water network system should be established and improved,and water supply should be made according to the situation and classification to achieve optimal water use.Meanwhile,the management of mountain ponds should be included in the construction of water network system to better play the group benefits of mountain ponds in Liuyang City.For the problem of water scarcity in Liuyang City,it is necessary to pay attention to the collaborative management of water quantity and water quality,and improve the water resources detection and supervision system.In addition,fully consider the crop growth water requirements,on the premise of meeting the basic needs of life,explore the appropriate agricultural planting structure,to promote the sustainable development of water resources in Liuyang City. |
