Multi-temporal Dynamic Monitoring Of Rocky Desertification In Karst Areas Of Guangxi

Rocky desertification is a land degradation phenomenon,which has a serious impact on the ecological environment and social economy.Pingguo County has a large area of peak cluster depression landform,which is a typical karst landform.This study starts with the short-term dynamic changes of rocky desertification,selects remote sensing images with different spatial resolutions,uses scale up and other research methods to compensate for the low resolution of medium-resolution LANDSAT-8 OLI images,and avoids the long period and coverage area of high-resolution images.The characteristics of small and weak continuity,use the modified LANDSAT-8 OLI image to classify the intensity of rock desertification in the karst area of Pingguo County,explore the temporal and spatial changes of the rocky desertification land in the karst area of Pingguo County,and clarify the rock desertification Internal transfer law to realize multi-temporal dynamic monitoring of rocky desertification areas that can quickly locate key issues.The main conclusions are as follows:(1)Land cover classification was performed on the images of LANDSAT-8 OLI in 2018,of which the supervised classification accuracy was the highest,the overall classification accuracy was 83.49%,and Kappa=0.8062.The object-oriented classification method was used to classify the PMS image of Gaofen No.1,and the overall classification accuracy was 82.11%.The area of forest land and cultivated land in Pingguo County has continued to increase for three consecutive years,while the area of grassland and bare land has declined for three consecutive years..(2)In this paper,the resampling of vegetation coverage of the GF-1PMS image and the NDVI value of the LANDSAT-8 OLI image in 2018 were used for regression analysis,and the NDVI value of the LANDSAT-8 OLI image in 2018 was corrected accordingly.The fitted degree after correction is higher than before,the correction result is better.(3)In this paper,the pixel dichotomy model method was used to invert vegetation coverage.The results showed that 0-20%,20-40%,and 40-60%have been declining for 3 years,60-80%and 80-100 The%grade has been growing for 3 years.The vegetation coverage of Pingguo County has been changing positively in the past three years.This study screened out four indicators:vegetation coverage,exposed bedrock rate,land cover type and slope.Using weighted overlay analysis,it was concluded that the rocky desertification area of karst areas in Pingguo County from 2017 to 2019 was 386km2 and 342.48km2 And 284.19km2,accounting for 26.98%,23.94%,and 19.86%of the total area of rocky desertification,respectively.(4)The rocky desertification in Pingguo County is mainly in the form of a strip.The situation in the north is better,mostly in areas with mild rocky desertification and in areas without rocky desertification.The distribution of large and moderate rocky desertification areas is relatively concentrated.Since 2017-2019,the degree of rocky desertification in Pingguo County has generally improved,and the area of severe rocky desertification has decreased.The main part of internal transfer is the improvement of moderate rocky desertification and potential rocky desertification.The improvement rate of the potential rocky desertification areas,which accounted for the highest total area of rocky desertification in 2017,was 54.39%.(5)Pingguo County may consider intensifying its control efforts to strive for a higher rate of control of rocky desertification.Gradually shift the focus of work to areas with moderate rocky desertification,shifting it to mild rocky desertification,mild transfer to potential,and potential to no rocky desertification.The areas with severe rocky desertification continue to deteriorate,vigorously manage the areas with moderate rocky desertification,and appropriately improve the areas with severe rocky desertification.