Integrated Ecological Risk Assessment Of Guangxi Xijiang River Basin Based On OWA-GIS

Regional integrated ecological risk assessment refers to the identification of risk sources like undue human activities and natural disasters doing harm to ecological environment,the adverse impact as well as risk level.The exploration of regional ecological risk status under the influence of multiple risks helps to get a comprehensive understanding of ecological risks and take effective measures,which is of great importance for maintaining stable ecosystem.Xijiang River occupying an important position in national strategies has obvious geographical advantage and abundant resources.However,with rapid social and economic development of the basin,it has led to a decline in vegetation coverage and biodiversity and increase in natural disasters.Human activities have impacted the ecological environment of Xijiang River Basin greatly,which do harm to a harmonious relationship between human beings and land so that the ecological environment becomes more vulnerable,threatening ecological security.In the long-term,sustainable development is hard to maintain.Under the requirements of sustainable socio-economic development,resource utilization and ecological protection,it is of great significance to explore the integrated ecological risks of Xijiang River.This paper takes Xijiang River as research area:Firstly,construct regression model and making grid analysis to obtain high-precision population density and GDP per capita;then,constructing evaluation index system based on DPSIR;Finally,combined with GIS and OWA method to make research on integrated ecological risk assessment of Xijiang River in Guangxi under different risk preferences.The main results are as follows:?1?Socio-economic Index Spatialization SimulationThe NPP-VIIRS nighttime lighting data has high spatial resolution and close relationship with population and GDP.It is one of the ideal data sources for realizing population density and spatial GDP per capita.The results of population spatialization shows that it can refine population at the county?district?scale by constructing stepwise regression model,model determination coefficient?R²?reaching 0.703 based on NPP-VIIRS nighttime lighting data,land use of study area and population of each county constructing a stepwise regression model that can refine population density at county scale,model determination coefficient(R²)reaching0.703.The accuracy verification shows the simulation result more accurate compared with existing research.The results of GDP spatialization show that the imitative effect between the three industries is better.Among them,the first industry and the power function of cultivated land area have the highest goodness of fit,R²=0.718;The TNL has the strongest correlation with the sum of the second and third industries'value,graded fitting R² above 0.878 and error estimation rate only 6%.Overall,the simulation accuracy is high.Based on NPP-VIIRS nighttime lighting data,it can achieve Socio-economic Index Spatialization Simulation and provide data for later integrated ecological risk assessment.?2?Integrated Ecological Risk Evaluation Index System ConstructionIt is to get an overview of the natural environment of Xijiang River and analyze the main ecological problems currently.Adopting“driving force-pressure-state-impact-response”?DPSIR?model,according to the principle of index selection,21 representative indicators were selected to construct an integrated ecological risk assessment index system.?3?Integrated Ecological Risk Evaluation Based on GIS-OWA MethodAdopt GIS-OWA method to make evaluation and select seven decision risk coefficient to make analysis of integrated ecological risk under multi-scenario.The decision risk coefficient ranges from??0 to???,which indicates that the attitude of decision makers changes from optimistic to pessimistic.When??0,the risk was grade 1 as low-risk area;when???,grade 5as greatest-risk area.As coefficient increases,the risk of overall basin gradually increases.When??1,the area of low-risk area in the basin accounted for the largest proportion,up to 63.85%,and the remaining was medium-risk area.The result is consistent with that of WLC,indicating that the traditional layer superposition method is a special case of the OWA multi-criteria evaluation method.From results of multi-decision attitude evaluation,the integrated ecological risk of Xijiang River in the south is higher than that in the north and the urban center is at the largest risk.Taking multiple influencing factors into consideration and ruling out extreme situation,we can know that when?=1,indicating“maintaining”;?=0.5,“ignoring”;?=3 or?=10,“paying attention".In practice,decision makers need to make adjustments to the decision risk coefficient according to different objectives.