Ecological Vulnerability Assessment Of Yinma River Basin Based On SD And DPSIRM Model

With the increasing of the exploitation of natural resources and environment by human activities since the middle of the 20th century,the global environment had undergone dramatic changes,and a series of ecological crises,such as global warming,melting glaciers,extreme weather events,water pollution problems and biodiversity reduction,have sprung up,seriously affecting the sustainable development of socio-economic and ecological environment in various regions.These problems had attracted the attention of relevant research organizations and institutions at home and abroad.Among them,international organizations,led by the Intergovernmental Panel on Climate Change(IPCC),pointed out that vulnerability was the most serious challenge facing the global future in the context of climate change.Ecological vulnerability assessment had risen worldwide since the 1990s to address important issues in the field of regional sustainable development,global environmental status and development trends,providing a scientific basis for addressing the challenges of climate change and environmental issues and meeting the major needs of today’s world and our socio-economic sustainable development.China had vast territory and the climatic,ecological and environmental conditions are large differences.In the climate interlaced areas,ecological interlaced areas and other regions,the regional natural environment sensitivity was greater,coupled with the rapid development of social economy,the ecological environment interference to strengthen,resulting in a large number of ecological vulnerability areas.Yinma River basin located in cold and low mountain areas,where were sensitive to climate change,and regional socio-economic development was under great pressure on ecosystems because of limiting by natural conditions.Due to the long freezing period of winter in the area,the poor self-purification capacity of rivers,as well as rural surface source pollution entering rivers with the"spring flood"of melting snow in spring and the technical bottleneck of sewage treatment facilities under low temperature conditions,had caused great pressure on the environment.The study of ecological vulnerability assessment in this area could provide scientific basis for ecological restoration and reconstruction,and could also provide decision support for decision makers and managers,which was of great practical significance for the realization of regional sustainable development.This study taken the typical cold and low mountain river basin in Jilin Province,the Yinma River basin as the research object.Field sampling,the indoor experiment and the"3S"technology were applied as the data acquisition means.Some method such as trend analysis,M-K test,sen slope estimation,the grid GIS and so on were used to analysis.The data series included meteorological data,the basic geographic data,field sampling and laboratory test data,remote sensing interpretation data,social and economic statistics and other multi-source data.Through the impact of ecological vulnerability factors in the basin to identify and analyze,using the more advanced Driving force-Pressure-State-Impact-Response-Management(DPSIRM)causality model and system dynamics(SD)model,the conceptual framework of ecological vulnerability in Yinma River basin was constructed,and the evaluation model of evaluation index system was also established to evaluate the ecological vulnerability of the study area.The evaluation results are spatially expressed,the evolution mechanism and development trend of ecological vulnerability in the study area were analyzed,the ecological restoration ways and methods of ecological vulnerability areas were explored,and the protection mode and resource development and utilization methods of regional ecological vulnerability areas are discussed in order to provide decision support and basis for the restoration,reconstruction and sustainable development of regional ecological environment.The main conclusions of the study are as follows:(1)An analysis of the extreme climate event index for the characterization of climate change showed that the Yinma River basin was more obviously affected by global warming,showing an interannual upward trend of extreme high temperature index,an interannual decline trend of extreme low temperature index,and a decreasing trend of extreme precipitation index in interannual variation.From the spatial distribution,the extreme high temperature index showed a certain latitudinal direction zonality,the southern increase was small and the north increased greatly,the decline trend of the extreme low temperature index was decreasing from the southwest to the northeast,the extreme precipitation index decreases gradually from the southwestern to the middle,and the change amplitude in the northeast showed an increasing trend.Mutations in extreme temperature events in the Yinma River basin occur between 1980s and 1990s,and the mutation of extreme precipitation events was more complex.There were generally multiple mutation points.The rate of interannual change in extreme weather events has,to some extent,played a role in driving momentum and pressure to the vulnerability of ecosystems.(2)Yinma River basin was the key area of economic development in Jilin Province,and social and economic development is also one of the keys to ecological vulnerability.On the one hand,the population,economy and urbanization of the basin had put great pressure on the deterioration of the ecological vulnerability.On the other hand,the progress of social management could play a positive role in responding to the forward succession of ecosystems.(3)The trend change of the EVI index of the Yinma River basin during 2001-2015 showed that the areas with significant deterioration of EVI were mainly distributed among the three administrative districts including Changchun,Shuangyang District and Yitong County in the central and southwestern parts of the basin.Among them,the deterioration occurred more serious was Changchun,its serious deterioration of the region reached 28.43km~2,accounting for 57%of all serious deterioration areas.(4)Through the analysis of the variables and feedback relationship between the natural subsystem,the social economic subsystem and the resource environment subsystem,the structure flow diagram of the ecological vulnerability system of the Yinma River basin was finally established,which includes 12 state variables and the rate variables and auxiliary variables,showing the interaction relationship between different variables,It provided a basis for the construction of the evaluation index system of ecological vulnerability in the Yinma River basin.(5)Through the trend of spatial distribution of ecological vulnerability in the Yinma River basin in the 3 periods of 1995,2005 and 2015,it was shown that the ecological vulnerability was characterized by low vulnerability in the southeast region and stronger vulnerability in the south-western and northern regions.The areas prone to ecological vulnerability succession were usually concentrated in the southwest such as Yitong and the central zones such as Changchun,Dehui and other places.(6)From the spatial evolution of ecological vulnerability in different periods,the ecological vulnerability levels of the Yinma River basin in the 1995 and 2005 were generally moderate vulnerability,but the ecological vulnerability was developing in the trend of deterioration,manifested as increasing trend of moderately,heavily and extremely vulnerable zones and a shrinking trend in lightly and slightly vulnerable areas.The ecological vulnerability was generally heavily vulnerable level in 2015,and the area of heavily and extremely vulnerable areas expanded further compared to the previous two periods.(7)From the results of the distribution of ecological vulnerability in different administrative regions in the Yinma River basin,the ecological vulnerability index of 4 regions,Dehui,Nongan,Jiutai and Yitong,was larger.Shuangyang City and Panshi were mainly lightly and slightly vulnerability.The ecological vulnerability areas of various grades in Changchun was relatively balanced.(8)By constructing the triangular graph model of"pressure-state-response",the ecological vulnerability was classified.The results showed that the Yinma River basin administrative region were dominated by state-response vulnerability type in different periods,and the proportion of response factors was larger in other types.In 1995-2005,the vulnerability types change of all the counties towards the direction of"pressure-state".In 2005-2015,the change trend of Yongji County was to"response"direction,the rest of the counties were developing to"pressure-response"direction.On this basis,according to the different types of vulnerability characteristics,the vulnerability improvement measures for the inner districts of the basin were put forward.In addition,from the watershed scale,the paper put forward 3 concrete measures,such as coordinating population-resource-environment relationship,integrating integrated management information platform for the whole process of ecological vulnerability in watershed,and introducing ecological products to compensate different regions for development differences.