Abstract:

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 spatialtemporal 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.