| Rocky desertification leads to serious degradation of surface vegetation,soil loss,bare bedrock or gravel accumulation,showing a phenomenon of land degradation similar to desertification such as water shortage,less soil,poor soil quality,resulting in the decline of land bearing capacity and even the loss of land resources.Therefore,it is urgent to study the development characteristics and influence element of rocky desertification.In this study,Xingjie Town,Xichou County,Wenshan Prefecture,Yunnan Province,is taken as the research object,and bases on Landsat5 TM images of 1990,2003 and GF-2 images of 2015 of Xingjie Town.The analysis of spectral features and extraction of rocky desertification information,and the distribution of rocky desertification grade in there periods in the study area are obtained.On this basis,the quantitative,spatial distribution and evolution characteristics of rocky desertification are analyzed,the correlation between influencing factors and rocky desertification is studied,and the influence mechanism of rocky desertification is further discussed,which provide a scientific and accurate reference basis for the investigation and control of rocky desertification in the study area.The main research results of this thesis include:(1)Using sample-based object-oriented image classification technology,the rocky desertification information was interpreted and extracted from Landsat5 TM images of 1990,2003 and GF-2 images of 2015,and the classification system of rocky desertification grade was determined to be six categories: no rocky desertification,potential rocky desertification,mild rocky desertification,moderate rocky desertification,severe rocky desertification and extremely severe rocky desertification.According to the accuracy evaluation,the accuracy of rocky desertification classification results in the three periods are over 80%,and forming the image feature and interpretation mark of rocky desertification in the study area.(2)According to the analysis of the development degree and distribution characteristics of rocky desertification,it is concluded that the rocky desertification in Xingjie Town is mainly mild and moderate rocky desertification,accounting for more than 89% of rocky desertification of the total area in the region;It is mainlydistributed in the south and northwest of the town,including the rocky desertification-prone areas of south area of Laojie,Lahai and Sanguang Village Committees,and the northwest area with centered on the Mohe Village Committee.(3)The research on the evolution characteristics of rocky desertification shows that the area of rocky desertification in the study area increased,the degree became heavier,the speed and dynamics of rocky desertification were high from 1990 to 2003.The reduction of moderate,severe and extremely severe rocky desertification areas was particularly evident under the implementation of the Regulations of Returning Farmland to Forest and the comprehensive control of land remediation in severe rocky desertification areas from 2003 to 2015.There are five types of rocky desertification evolution: Aggravated,severely aggravated,stable,slightly improved,and significantly improved.It shows a gradual evolution pattern,supplemented by abrupt evolution patterns.(4)The study of rocky desertification and natural factors and human activity factors shows that rocky desertification is mainly distributed in carbonate rock areas and fault zones dominated by limestone and dolomite,and mainly distributed in sloping fields at altitudes of 1100 to 1300 m and slopes of 15 ??25 ?,the incidence rate of rocky desertification in the hillside area is high.When the road buffer distance is 1000?2000m,the incidence rate of rocky desertification reach its maximum.80%of the rocky desertification land is distributed in sparse residential areas.Rocky desertification land mostly occurs in dry land,sparse forest land and grassland,bare land and mining land,etc. |
PDF Full Text Request