雅砻江流域植被指数长时间序列变化分析

Analysis on vegetation index's long time series dynamics of Yalong River basin

土地覆被的变化直接体现和反映了人类活动的影响程度。本文以雅砻江流域水电开发为例,采用趋势线分析法、相关分析法等方法综合研究了流域1982-2006年24年间的植被覆被时空动态变化过程。研究结果表明,年最大NDVI值递减0.0004/年,多年植被覆被度状况:下游>中游>上游,而通过趋势线分析植被覆盖度增减情况是:上游>中游>下游。中下游的植被覆盖度多年来呈现出递减趋势这可能与电站建设活动及气候变异有关。同时分析了5个县市NDVI值与11个气候因子之间的关系,结果表明NDVI与平均气压、平均气温、平均最高气温、平均最低气温都有很强的相关性,Pearson相关系数分别为0.881、0.879、0.867、0.877。

Change in the vegetation cover of land directly incarnates and represents the influence of human activities.This paper analyzes the dynamics of vegetation cover with techniques of trend line analysis and correlation analysis and presents a case study of spatial and temporal variations of vegetation cover in the hydropower-developing Yalong River basin during the years 1982-2006.The results show that the annual maximal NDVI was reduced by 0.0004 every year and that the cover degree in the lower reach was better than that in the middle reach,while the latter was better than the upper reach.The cover in the middle and lower reaches took a decreasing trend over these years,which was probably caused by the hydropower construction activities and the climate change.An examination on the relationship of NDVI values versus 11 climatic factors for five counties reveals that the NDVI is strongly correlated with the mean values of pressure,temperature,maximum temperature and minimum temperature.The Pearson correlation coefficients of these factors are 0.881,0.879,0.867 and 0.877,respectively.