Temporal And Spatial Evolution Of Ecological Environment Quality In Qianzhong Water Control Project Area Based On RSEI And The Analysis Of Driving Mechanism

A good ecological environment quality is very important to the survival and development of human beings.In the process of continuous economic and social development,the ecological environment in which we live has also been affected and destroyed to varying degrees,and environmental issues have gradually attracted attention from all walks of life around the world.How to monitor and evaluate the quality of the ecological environment more objectively and comprehensively is a key issue that needs to be solved urgently for the healthy development of the region.The fragility of the ecological environment in the karst mountainous area is the main ecological and environmental problem faced by the ecological environment protection and high-quality social development in the Guizhou Plateau,due to the vulnerability of the karst area itself and the unreasonable utilization of human beings,ecological and environmental issues have become more sensitive.Therefore,how to quickly and timely monitor and evaluate the changes in the ecological environment of the major water conservancy project areas in the karst mountainous area is of great significance for the karst area to coordinate the balance between ecological environmental protection and economic and social development.The project area of central Guizhou water conservancy project is located in the mountainous area of karst plateau,the degree of rocky desertification is high,the ecological environment is fragile,and the contradiction between man and land is sharp.In order to monitor and evaluate the ecological environment condition of the major water conservancy project area in karst mountainous area,understand its space-time differentiation law,and analyze the response mechanism between water conservancy project and regional ecological environment.Based on GIS and remote sensing technology,remote sensing images of2000,2005,2010,2015 and 2020 are selected as the data basis of the study.A remote sensing ecological index（RSEI）assessment model was constructed,which was composed of four index factors: greenness（NDVI）,humidity（WET）,dryness（NDBSI）and heat（LST）.Principal component analysis（PCA）was used to calculate the remote sensing ecological index（RSEI）in the model.The temporal and spatial variation characteristics of ecological environmental quality in the study area during the past 21 years were quantitatively evaluated,and the driving mechanism behind it was analyzed by geographic detector.The main conclusions are as follows:（1）RSEI model of remote sensing ecological index can be coupled with the information of multiple ecological factors.Compared with a single ecological factor,RSEI model can better represent the overall situation of regional ecological environment.Principal component analysis results show that: Green and humidity,the result is positive,that the green degrees and the humidity of the study area ecological environment quality have positive positive influence,can promote the improvement of the ecological environment quality in the study area,and the result of the dryness and heat are negative,dryness and heat on ecological environmental quality in the study area is the negative impact of negative impede recovery and improve ecological environment in the study area.The mean values of RSEI in 2000,2005,2010,2015 and 2020 were 0.51,0.65,0.65,0.70 and 0.72,respectively.Except for the little change in 2005 and 2010,it shows a gradual upward trend,indicating that the ecological environment condition of the hydro-benefit project area in central Guizhou is gradually getting better.According to the changes of remote sensing ecological index grade,the area of ecological improvement was greater than that of ecological degradation from 2000 to 2020,and the ecological environment has been improved significantly in the past 21 years,and the overall ecological environment is developing steadily.From the point of view of spatial distribution,the changes are obvious in the regions mainly affected by human activities,and the regions with poor ecological environment are gradually improved by the implementation of ecological protection policies and the adjustment of central Guizhou water conservancy project.（2）From 2010 to 2020,the remote sensing ecological index changes in different degrees within 50 m,500m and 1000 m around the construction area of 39 trunk（branch）canals in central Guizhou Water conservancy project area.In general,there are 34 dry（branch）canals in the area of 50 m and 500 m,and the proportion of areas with improved remote sensing ecological index is greater than that with degradation,and the proportion of areas with improved remote sensing ecological index is smaller than that with degradation in the area of 5 dry（branch）canals.In the range of 1000 m,there were 35 dry（branch）canals,and the proportion of area with improved remote sensing ecological index was larger than that with degradation,and there were 4 dry（branch）canals,the proportion of area with improved remote sensing ecological index was smaller than that with degradation.The negative disturbance caused by human activities to the ecological environment is small in the areas where the improvement is greater than the degradation,and the ecological protection has achieved good results in the process of engineering construction.Human activities have caused great disturbance to the ecological environment,which should be paid attention to in the follow-up construction work.（3）The results of geographical detector showed that the order of the impact degree of each detection factor on eco-environmental quality was land use > slope > population density > elevation > soil type >precipitation > lithology.Among them,human activities,especially land use factors,explain RSEI the most,which is the main driving factor of ecological environment quality.The impact of detection factors on the ecological environment is not the direct and independent result of a single impact factor,nor a simple superposition of multiple factors,but the resultant force formed by the synergistic interaction of topographic factors,meteorological factors,human activities,geomorphology,soil and other impact factors.In the study of this paper,there are only two kinds of enhancement relations among the interaction between the detection factors,namely two-factor enhancement and nonlinear enhancement,and there is no independent or weakened situation.Moreover,the effect of such interactive enhancement effect on the ecological index is greater than that of single factor.As time changes,to detect the influence degree of factors on the ecological environment have some differences,its explanatory power q value,and the reasons of difference in different years of vegetation growth,surface morphology and the influence of soil and water conservation ecological conditions,such as,in addition,may also with other factors of appeared in the area of impact on ecological environment,These reasons together lead to the spatial differentiation of ecological environment for many years.Through the change of Q value,the leading factors causing the spatio-temporal differentiation of eco-environmental quality can be identified,which has a certain indicating role in analyzing the mechanism of eco-environmental quality change and formulating eco-environmental protection measures.