雅鲁藏布江流域近13年植被覆盖动态监测及与降水因子的相关性分析

ANALYSIS OF DYNAMIC MONITORING OF VEGETATION CHANGE AND THE CORRELATION WITH PRECIPITATION FACTOR IN YALU TSANGPO RIVER BASIN DURING THE PAST 13 YEARS

基于MODIS-NDVI和SPOT-VGT遥感数据探讨了雅鲁藏布江流域1998、2004、2010年植被覆盖度的空间格局和变化规律,并从空间上利用重心模型、从时间上利用相关系数模型分析了降雨因子对雅鲁藏布江流域植被生长的影响。结果表明:(1)雅鲁藏布江流域植被覆盖度整体呈上升趋势,表现为低等和中低等覆盖度面积减少,而高等和中高等级有所增大;(2)从变化强度来看,雅鲁藏布江流域的植被覆盖相对较稳定,3个时期的植被盖度变化都以稳定和轻微变化为主,此类变化强度的地区主要集中在上游和下游受人类活动影响较小的区域且其面积比例在3个时期都达到了70%以上;(3)雅鲁藏布江流域植被NDVI年际变化、月际变化与降水分别在空间重心迁移和滞后效应上均表现为较大的正相关性。

Based on the traditional dimidiated pixel model,the vegetation fractions of 1998,2004 and 2010 were inversed respectively with the dataset of MODIS （NDVI） and SPOT VGT.Then,the spatialtemporal relationships between precipitation and vegetation fractions were analyzed using the models of gravity center and coefficients.The results showed that：（1） the vegetation fraction of Yalu Tsangpo River basin during the past 13 years has demonstrated an increasing trend,which was indicated by that areas of low and medium-low vegetation fraction decreased while those of medium and medium-high vegetation fraction had an increasing trend.（2） In terms of vegetation fraction change intensity,the vegetation fraction has been much stable for the past thirteen years with the stable,slightly-increasing,increasing region occupying about 70% of the whole basin,where were influenced seriously by the human activities.（3） The time-series NDVI and precipitation of Yalu Tsangpo River basin had a positive relationship both in the transfer trajectory of gravity center and time-lag effects.