| Karst rocky desertification is the third largest ecological problem after the desertification and the soil erosion.Based on the research of the predecessors,this paper takes the typical karst area of the Nandong River basin as the research area according to the actual needs of Karst rocky desertification investigation,monitoring and governance in Southwest China,By using remote sensing technology,the investigation and dynamic monitoring and evaluation of Karst rocky desertification changing from 2000 to 2015 in the Nandong River basin was carried out,discuss the forming mechanism of Karst rocky desertification in the Nandong River basin,which provides scientific reference for the prevention and control planning of Karst rocky desertification in the basin.In this study,Landsat image data of three phases in 2000,2009 and 2015 were used as remote sensing data sources to extract rock bareness and vegetation coverage.ASTER GDEM data were used to generate slope for terrain data source.5 million hydrogeological maps obtained lithologic distribution.Based on the classification of rocky desertification rate,the change rule of karst rocky desertification in two time periods was statistically analyzed,and the results of rocky desertification and other data were analyzed statistically to discuss the forming mechanism of Karst rocky desertification in the Nandong River basin.The research results were as follows:(1)Constructing the normalized rock index by short-wave infrared band and near-infrared band,dividing the rocky desertification level,and extracting the information of rock bareness in the typical karst area.This is a fast,economical,effective and practical new method of remote sensing.The field verification of the research results shows that the correct rate of rocky desertification is 83.05%.(2)Using Landsat remote sensing data of three periods in 2000,2009 and 2015,the rocky desertification distribution of different grades in the study area was obtained by using the information of rock nudity.The results show that the rocky desertification is still severe in the study area,and the rocky desertification accounts for more than 76%of the total karst area in the study area,and the moderate and severe rocky desertification is the main.(3)The remote sensing dynamic monitoring of karst rocky desertification in the study area was carried out by using the difference method.The distribution of rocky desertification degree from 2000 to 2009 and 2009 to 2015 was obtained.Among them,from 2000 to 2009,the area of rocky desertification increased by 621.57hm2 in 2000,the rocky desertification area in the study area intensified.And rocky desertification area than in 2009 reduced by 1319.43hm2.It was well contained in the period from 2009 to 2015.The evolution of rocky desertification in the study area from 2000 to 2015 shows a significant deterioration and then improve the trend,indicating that since 2008,the national rock desertification control achieved initial results.(4)The results show that the distribution of limestone of Ge jiu formation(T2g)is the largest,and it is the main distribution stratum of rocky desertification in the area.(5)The results of the superposition of rocky desertification and terrain slope show that moderate rocky desertification area increased with the increase of slope,that is with the increase of slope soil erosion in rocky desertification area increased;and severe rocky desertification are showing the opposite trend,with the increase of the slope of the terrain,heavy stone desertification area decreased,the analysis is the frequent human activities and strength,lead to strong rocky desertification results.(6)Rocky desertification and vegetation cover spatial overlay analysis results show that the severe rocky desertification area with the increase of vegetation coverage decreased,moderate,mild rocky desertification area with the increase of vegetation coverage increased first and then decreased.The vegetation coverage is less than 30%,with severe rocky desertification.The vegetation coverage is 30%?50%in the moderate rocky desertification.The vegetation coverage is greater than 50%with mild rocky desertification. |
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