Remote Sensing Evaluation Of The Spatio-temporal Evolution And Environmental Effects Of Rural Residential Areas In Hengdong County

Studying the distribution status and spatiotemporal evolution process of rural settlements,understanding the impact of the development and evolution of rural settlements on the environment,is of great significance to the overall rational layout and optimization of rural settlements and protecting the ecological environment.Based on Landsat TM data,this paper extracts vector data of rural settlements in Hengdong County,and uses GIS spatial analysis methods to analyze the evolution of rural settlements in Hengdong County in terms of time,space,and driving force.The environmental effect assessment has drawn the following conclusions:(1)Landsat TM has limitations as a medium-resolution image classification,and the distribution of rural settlements in hilly areas is fragmented and small in scale,which increases the difficulty of extraction.In order to improve the classification accuracy,this experiment adopts the method of combining man and machine,and uses support vector machines to classify remote sensing images.The extracted construction land is manually modified with reference to Google Earth and the land use survey in Hengdong County,and the rural areas of Hengdong County are obtained.Residential area.(2)In terms of quantitative characteristics,the area of rural residential areas in Hengdong County increased from 35.5 km2 in 1990 to 154.46 km2 in 2017,an increase of 335.10%.In terms of spatial characteristics,the spatial distribution of rural residential areas in Hengdong County in 1990,1999,2009,and 2017 showed an agglomeration pattern as a whole,and showed a significant high-value agglomeration phenomenon.Rural residential areas and new residential areas in Hengdong County are affected by natural and human factors,and their spatial distribution rules have obvious regional differences.From 1990 to 2017,more than 95% of the residential areas and new residential areas were distributed in areas with an elevation of 0-200 m and a slope of 0-20°;residential areas in Hengdong County and hot spots and dense areas of expanded residential areas Most of them are located along the Xiangjiang River and Laishui River;in addition,the population growth rate of Hengdong County is small,which is inconsistent with the large expansion of rural residential areas,and the phenomenon of unreasonable land use and "hollow residential areas" has occurred.The rapid economic development has promoted the substantial expansion of rural settlements.(3)From 1990 to 2017,the ecological environment quality of Hengdong County decreased first and then increased.The average EQI of Hengdong County Ecological Environment Quality Index in 1990,1999,2009,and 2017 were 58.26,54.55,58.36,59.93,respectively.The quality of the ecological environment deteriorated significantly in 1999,the quality of the ecological environment improved significantly from 1999 to2009,and the quality of the ecological environment improved slightly from 2009 to2017.(4)Generally speaking,the ecological environment quality in densely populated areas is relatively poor;the expansion of residential areas will bring certain negative impacts on the ecological environment,but it will not lead to absolute deterioration of the ecological environment;the intensity of changes in residential areas affects the quality of the ecological environment.The more drastic the point change,the greater the degradation of the ecological environment quality.