Remote Sensing Investigation And Research On Ecological Status Changes In Qinling Mountains Of Huyi District In Xi’an

The Qinling Mountains in Huyi District on the southern margin of Guanzhong Plain have important ecological barrier protection and water conservation functions.However,with the acceleration of urbanization and the rise of tourism,the north of the Qinling Mountains has become an important development and construction and tourism hotspot,resulting in blind development and large-scale illegal construction.In addition,deforestation and sewage discharge have led to increasingly prominent ecological and environmental problems such as landslides,water pollution,and river drying.With the implementation of the “14th-Five Year Plan”,ecological protection of the environment in the Qinling Mountains has been further emphasized.Therefore,based on 4 Landsat TM and 2 OLI images and combined with highresolution imagery such as Google Satellite Map,this article selects the northern Qinling Mountains as a research subject for conducting long-term monitoring of land cover change,landscape patterns,and ecological environmental quality change over 30 years.Combining GIS and RS technology,we also conduct field investigations to comprehensively analyze the local ecological problems from the ecological and geological point of view in the region,and propose appropriate measures and suggestions to provide a reference for ecological environmental protection and land rational planning in the study area.The main results are as follows:(1)By comparing and analyzing the classification accuracy of Support Vector Machine(SVM)and Random Forest(RF),the results show that the classification accuracy of SVM is better.The land use types in the study area are divided into six categories: forest land,construction land,farmland,grassland,water area and unused land.(2)In studying land use change,the methods of single land use dynamics degree,comprehensive land use dynamics degree,comprehensive land use index,and transfer matrix are used for analysis.The results show that the degree of land use in the region has been steadily declining over the past 30 years,with the overall area of forest land and construction land showing an increasing trend,and the rate of land use change in both is relatively fast.While the land area of cultivated land,water area,grasslands and unused land show a decreasing trend.Notably,the transfer of forest land,cultivated land,and construction land is relatively severe.In the analysis of landscape patterns,from the perspectives of patch type and landscape level,the landscape pattern in the study area tends to be highly fragmented,with strong irregularity in the shape of farmland and construction land landscapes.The dominant role of forest and farmland landscapes is weakening.The above results suggest that the implementation of policies of “forest rehabilitation from slope agriculture” and “urban and rural planning” have effectively alleviated the contradiction between people and land,promoted the changes in landscape patterns in the study area,and improved the protection and development of ecological environment and security.(3)The Remote Sensing Ecosystem Index(RSEI)is determined for each year by calculating four indicators: NDVI,WET,NDSI,and LSI.The overall RSEI average of the study area shows an uptrend in the “N-shape” and the overall ecological environmental quality is good to excellent.From the spatial distribution characteristics of the ecological quality,it can be seen that the ecological quality of the southern mountainous areas is better than that of the northern areas with dense human activities,and land use changes have an impact on the ecological environment.(4)This study uses the Analytic Hierarchy Process(AHP)to select six index factors including slope,slope direction,elevation,land use type,water system buffer distance,and vegetation cover to construct an index system to assess ecological sensitivity.The results show that the high-sensitivity areas are widespread in the south and center of the high-altitude study area,with ecological problems such as soil erosion and dry riverbed.While the medium and lowsensitivity areas are concentrated in low-terrain towns in the northern part of the region and the transition areas between mountainous and mountainous areas towns,with environmental damage occurring.We also select 9 indicators,including elevation,slope,slope direction,curvature,geotechnical type,water system distance,road distance,and fault distance,and use the information set model to construct the geological hazard vulnerability assessment system.The areas of high biological hazard are concentrated in the north of the area,near roads or rivers,and human activities are relatively intense.The ecological environment is fragile and prone to geological disasters,which further exacerbate ecological problems.The areas untouched by geological disasters are concentrated in the southern and central areas of the region,which are mostly uninhabited or sparsely populated areas with fewer ecological problems caused by geological disasters.