Best Management Practices Based On InVEST Model In Jinghe River Basin

Affected by climate change,population growth and the development of industry and agriculture,a basin is often faced with many problems such as water resources,water environment,water ecology,water and sediment,which seriously affect the high-quality development and ecosystem service function of the basin.As the largest tributary of the Weihe River basin,the Jinghe River is the main agricultural water source in Guanzhong area.At the same time,the Jinghe River is also one of the main sediment-producing areas in the Yellow River basin,the soil erosion is extremely serious,the water pollution is also increasing,and the ecosystem service function of the basin is seriously threatened.In view of the various problems in the Jinghe River basin and in response to the requirements of ecological protection and high-quality development of the Yellow River basin,it is necessary to take measures according to local conditions to improve the ecosystem service function of the Jinghe river basin.Therefore,this study takes the Jinghe River basin as the research object,first completes the land use classification of the Jinghe River basin in 2020 on the GEE cloud platform,then evaluates the response and current situation of water yield,carbon storage,soil conservation,nutrient transport and crop production functions to land use change in the Jinghe River basin based on the InVEST model,and analyzes the synergies and trade-offs between different ecosystem services in the Jinghe River basin.The corresponding objectives and constraints should be set according to the relevant national policies such as the draft Law of the people’s Republic of China on the Protection of the Yellow River and the actual situation of the Jinghe River Basin,and the multi-objective simulation optimization model of Best Management Practices(BMPs)spatial allocation is constructed to optimize the spatial allocation of BMPs for the typical sub-basin of Jinghe River basin.Finally,the benefit of the optimal scheme is evaluated.It is expected to provide scientific basis and technical support for the decision-making and implementation of BMPs and other ecological restoration projects in other areas of the Loess Plateau or areas with similar climatic and hydrogeological conditions to the Jinghe River basin.The main conclusions of this paper are as follows:(1)The current situation of five ecosystem services of water yield,carbon storage,soil conservation,nutrient transport and crop yield in Jinghe River basin in 2020 were quantitatively analyzed.The results show that InVEST model can produce acceptable spatial distribution and quantitative value of ecosystem services in Jinghe River basin.(2)Based on the modules of water yield,soil conservation and carbon storage in InVEST model,the changes of ecosystem services and their responses to land use change in Jinghe River basin from 2000 to 2015 were quantitatively analyzed,and the trade-offs among different ecosystem services were analyzed.From 2000 to 2015,the average annual water yield of the Jinghe River basin was 1.11×10~9m~3,which was 36.2%lower than the average of the previous 50 years.The average annual sediment export in the Jinghe River basin is 9.67×10~7t,which is 60.7%lower than the average of the previous 50 years.Unsurprisingly,carbon storage has increased 5907559.28 mg,about 2.4%more compared to 2000.These data show that there are trade-offs between water yield and sediment control as well as carbon storage,and there are synergies between sediment control and carbon storage.In addition,the t-test results of sub-basins showed that in the Loess Plateau with relatively limited rainfall,grass is a better BMPs optimized vegetation type than trees.(3)Combined with NSGA-Ⅲoptimization algorithm,considering the synergies and trade-offs effect between different ecosystem services,setting constraints according to water yield constraints,crop yield constraints and BMPs that can be adopted at different slope positions,,taking the maximum water yield,carbon storage,crop yield,minimizing nutrient transport and soil erosion as the optimization objectives,taking the land as the allocation unit,and combining with the slope position of the land,the multi-objective simulation optimization model of BMPs spatial allocation is constructed in the typical sub-basin of Jinghe River basin.The spatial optimal allocation of BMPs is carried out in the sub-basin.A series of Pareto optimal sets are obtained.Decision makers and managers can choose the appropriate optimization scheme according to the actual situation and needs.Through the analysis of these schemes,it can also be found that there is an obvious synergies and trade-offs among different ecosystem services in Jinghe River basin.There are trade-offs between water yield and soil conservation,between crop yield and nutrient transport,between carbon storage and water yield.There are synergies between soil conservation and carbon storage.In order to improve one or more ecosystem services,the trade-offs between ecosystem services should not be ignored,otherwise it may lead to the reduction of other ecosystem services.In order to achieve the security and sustainable development of ecosystem services,the trade-offs and synergies between ecosystem services must be comprehensively considered.