Quantitative Analysis On The Impact Of Climate Change On The Water-food-energy-ecology Nexus In Irrigation Areas

The nexus among water,food,energy and ecology is interrelated,interdependent and competitive.With its advantages of multi-resource coordination,multi-sectoral collaboration and multi-level management to promote development,it has become a new comprehensive method to explore the joint evolution with ecology,climate change,human activities and socio-economic development,aiming to formulate effective sustainable development strategies and policies,and avoid the risks caused by interrelationship among resources.As an important grain production base and a major agricultural water user,the Baojixia irrigation district is of great significance to the agricultural development of the Weihe River Basin and Shaanxi Province.Intensive and continuous agricultural activities have led to serious water shortages and threats to ecological security,and contradictions between supply and demand for food production and energy consumption.Disorderly extraction of groundwater and the high sensitivity of agricultural water resources to climate change further exacerbate the fragility of the nexus.Therefore,it is necessary to pay more attention to and assess the impact of surface water and groundwater extraction and utilization on crop irrigation and ecological security in the irrigation area.From a holistic and comprehensive perspective,study the synergies and trade-offs among the nexus and quantitatively analyze the impact of climate change,providing effective improvement measures and strategies for each relevant department to ensure safe and sustainable development.At present,there are few analyses of trade-offs and synergies and quantitative modeling in China,and there is no in-depth and meticulous research based on hydrological models.Therefore,this study takes the Baojixia irrigation district as the research object,defines the quantitative indicators and applies the sustainability index and Pearson correlation analysis,aiming to propose a quantitative analysis framework based on the WEAP-MODFLOW coupled hydrological model.Then establish a series of climate change scenarios and combining managements scenarios for quantitative analysis of these impacts on the nexus.The study has reached the following conclusions:(1)Five quantitative indicators and sustainability index are defined,and a quantitative analysis framework is provided for the water-food-energy-ecology nexus.The research shows that considering multiple climate change scenarios within the quantitative analysis framework based on the combination of the coupling model and quantitative indicators and combining supply and demand management measures,can not only fully reflect and quantify the trade-offs and synergies among the resources,but also provide targeted management suggestions for different sectors,thereby promoting sustainable development of the nexus.(2)The coupled WEAP-MODFLOW model is applied to the research field of the water-food-energy-ecological nexus.The model realizes the cycle simulation and joint calculation between surface and groundwater in the channel-well combined irrigation area,and quantitatively calculates the proportion of groundwater supply irrigation,as well as groundwater recharge and water level changes in the scenario analysis.Results show that the trend of groundwater resource utilization in different hydrological years is significantly different:the average groundwater supply in the wet year scenario decreases by 5.7%,the cumulative groundwater recharge and water level restoration value are higher than the overall average.While in the drought year scenario,the scope of groundwater exploitation is expanded,the cumulative recharge is reduced by an average of 10%,and the decline in groundwater level is the maximum,which would threaten the future groundwater ecology and the safety of basic ecological flow in the river.(3)Quantitative analysis of climate change impacts shows that climate change significantly affects water resource utilization and crop irrigation demand through changes in meteorological factors such as precipitation and temperature,which has a potentially non-negligible fluctuation impact on the nexus.The demand for crop irrigation will show an upward trend in the future,and the groundwater level will fall sharply during the 2032-2035 with a maximum close to-5m,which will increase the risk of water level changes below the Weihe Riverbed,resulting in the lack of recharge for river ecological flow and exacerbating the vulnerability of ecological security.Under extreme drought scenarios,the tension among water availability,energy consumption and demand for food production has been strengthened,resulting in a decline in the nexu sustainability(the sustainability index is below 13 per cent of the overall average).(4)Combined with water-saving irrigation and changing cropping pattern scenarios,it shows that integrated management measures can play different roles in alleviating water shortages,imbalance of groundwater extraction and replenishment,ecological security,and pressure of energy consumption.Under the influence of extreme drought,results show an average increase of 16 per cent in total food production,a 2.3 per cent decrease in the proportion of groundwater exploitation and a recovered value of 48 per cent in the groundwater table compared to the climate change scenario.There is also an increase of 16.5 per cent in quantitative indicators of ecological factors and a 19 per cent reduction in energy consumption compared with the water-saving irrigation scenario.These results in a 25 per cent increase in the sustainability index.