基于高分一号的敖江流域水源保护区植被变化监测

Vegetation Change Monitoring in Aojiang River Watershed Protected Area Based on GF-1

利用2013-10、2014-11和2015-10三期敖江流域水源保护区的高分一号(GF-1)数据,通过主成分分析(principal component analysis,PCA)和变化向量分析(changevector analysis,CVA),并利用局部最小错分概率法自动确定阈值,获得植被变化区域;利用变化区域的NDVI分析植被覆盖变化情况。通过对敖江流域水源保护区进行了不同缓冲区与不同市县两个尺度的量化分析,结果表明,2013～2014年、2014～2015年敖江流域(5km缓冲区内)的植被质量以改善为主,改善面积分别为退化面积的1.27倍和1.38倍,而2013～2014年植被变化情况是缓冲区越小植被改善越大,2014～2015年却是缓冲区越大植被改善越大。从不同市县植被差值指数看,2013～2014、2014～2015年植被退化最明显的区域为下游的连江县,退化面积所占植被变化面积的比例由6.7%上升到17.41%,而植被改善面积最大上游的古田县,改善面积所占植被变化面积的比例由19.38%上升到27.56%。

Vegetation cover and its change are important indicators of regional environmental change and it is of great significance to the ecological status of both sides of the river.This paper adopts the principal component analysis and the change vector analysis to analyze first the data of GF-1 of Aojiang River Basin Water Conservation Area in October 2013,November 2014 and October 2015 respectively,and then uses the local minimum misclassification probability method that can automatically determine the threshold value to obtain the vegetation change area.Finally,the change of vegetation coverage is analyzed by NDVI.The quantitative analysis of the buffer zone and different cities and counties in Aojiang river water source protection area shows the improvement of vegetation quality in the Aojiang River Basin(within 5km buffer zone)during 2013-2014:the improved area during 2014-2015 was 1.27 times and 1.38 times higher than that in the degraded area,respectively.The vegetation change during 2013-2014 is that the smaller the buffer area is,the greater the vegetation improvement,while during 2014-2015 the greater the buffer zone is,the greater the vegetation improvement.From the differences of vegetation index of different cities and counties,the most obvious area of degraded vegetation during 2013-2014 and 2014-2015 is Lianjiang County with proportion of degraded area occupied by vegetation changing from 6.7% to 17.41%.In Gutian County with the largest area of improvement,the proportion of the area of vegetation change increases from 19.38% to 27.56%.