Study On Early Warning Of Ecological Security In East Liaohe River Basin Based On Scenario Simulation

With the rapid economic growth,urbanization and global climate change,the ecological environment of the river basin is deteriorating,and the destruction of the ecosystem is becoming more and more serious.The potential ecological crisis may damage China’s sustainable development and affect people’s living conditions.The river is the main artery of a region,and the river basin is the main natural space where man and nature coexist,which is closely related to the regional social and economic development.As a complete ecological unit,watershed has strong integrity and high spatial heterogeneity.In view of the trend of economic development and ecological deterioration,the basin ecosystem has suffered great damage.It is a new challenge to assess the ecological security of the basin and decipher its driving mechanism.Ecological security early warning(ESEW)research is an effective way to define the bottom line of unsustainability,watershed management and auxiliary decision–making.In addition,a new study shows that the increase of climate change will rapidly reduce global ecological security,and the evolution of ecological landscape pattern will also change ecological security.Therefore,it is necessary to clarify the development trend of watershed ecological security waring,determine the driving mechanism of climate change and landscape change and the internal influences of social,economic,ecological environment and resources,etc.The results of attribution analysis can provide insights for improving the management of watershed ecosystem restoration plan.The research results have important scientific significance and practical application value,and have broad prospects.This study took the East Liaohe River Basin(ELRB)as the research area,collected the data of remote sensing,meteorology,ecological environment,statistical yearbook and landform,and adopted the methods of comprehensive weighted evaluation,Geographic detector(GD),Bayesian network model(BN),scenario analysis and 3S technology to build the comprehensive evaluation model of ecological security warning in the basin,and evaluated the ecological security warning in this area.Firstly,the System dynamics model(SD)is used to establish a new ESEW system composed of core system and external system,and its complex causal relationship is analyzed.Then,the Driving force–Pressure–State–Influence–Response–Management(DPSIRM)conceptual model was used to construct the ecological security early warning evaluation index system of the basin,and the ecological security warning of the study area was evaluated in time and space from 2000 to 2020.Using the GD,the internal influence,driving factors and synergistic effects of ecological security warning changes in different periods of the basin were quantified and identified from three levels: index level,criterion level and system level.On this basis,combined with BN and scenario analysis,univariate and multivariate scenarios were set up to simulate the risk of ESEW in the basin under different scenarios.The main research results are as follows:(1)From 2000 to 2020,the spatial and temporal distribution trend of ecological security warning in the ELRB showed significant differences between east and west.High warning areas such as extreme warning and severe warning alert are mainly distributed in the northwest of the study area.In 2000,the ecological security situation of the ELRB was poor,and about one quarter of the area was in high warning,because the downstream of the basin was other landscape types except forest land and human activities were intense.From 2005 to 2010,the ecological environment of the basin was improved,but there were still some dangers.In 2015,the basin ecological environment changed from good level to critical level of risk level.The ecological security of the river basin will be improved in 2020.(2)From the distribution of ESEW levels in different administrative regions of the ELRB,the ESEW levels in Lishu,Gongzhuling,Shuangliao,Dongfeng and other regions are alleviated,while the ESEW levels in Siping,Yitong,Liaoyuan and Dong Liao are aggravated.(3)Based on the GD factor detector to identify the internal influence,external driving factors and the influence degree of criterion layer on the spatial differentiation of ecological security alert in the ELRB,it is found that there are obvious differences in the influence and driving degree of each factor on the ecological security warnin in the basin from 2000 to 2020,and the q value changes greatly.From the perspective of internal influence degree,per capita resource volume was the most important internal factor affecting the change of ecological security warning in the basin from 2000 to 2005.The key internal influencing factors from 2010 to 2020 are natural population growth rate,conversion rate of ecological land to non–ecological land and urbanization rate.From the perspective of external driving degree,the annual mean temperature is the most important driving factor of ecological security warning change in the ELRB during 2000–2020.From the criterion level,management,response and state have the strongest influence on the change of watershed ecological security alert.The results of interaction detector show that the synergistic effect between internal factors and external driving factors is manifested as double factor enhancement or nonlinear enhancement,which indicates that the change of watershed ESEW is comprehensive,not formed by a single factor,and the interaction between factors strengthens the influence of a single factor.(4)The probabilistic analysis of ESEW levels in the ELRB under different scenarios shows that the BN model of ecological security warning in the ELRB can better simulate the intensity and uncertainty of causal relationship between variables in the ESEW system.Scenarios with high slope and low urbanization rate can significantly reduce the probability of high ESEW level.High elevation–high domestic sewage discharge,high per capita water resources–high elevation,high urbanization rate–high elevation,high ecological land to non–ecological land rate–high elevation,high ecological land to non–ecological land rate–medium elevation,high ecological land to non–ecological land rate–high elevation,low annual mean temperature–landscape uniformity significantly reduced the occurrence of high warning risk of ecological security in the ELRB.The core system measures and external system measures should be combined to effectively alleviate the ecological security of the basin.The results of this study are of great significance for the protection and sustainable management of basin ecosystems,and can provide valuable references and suggestions for the basin ecosystems under the driving force of climate change and landscape pattern change,and under the influence of natural and human activities.