基于NDVI的淮河流域植被覆盖度动态变化

DYNAMIC CHANGES OF NDVI-BASED VEGETATION COVERAGE OF HUAI RIVER BASIN

基于淮河流域1998～2005年每年第三季度的SPOT-VEGETATION逐旬NDVI数据,采用MVC法(最大值合成法)获得月NDVI值,用均值法求取季均NDVI值,然后用像元二分模型求得各年的植被覆盖度。在此基础上,从不同角度分析近8年植被覆盖度的变化情况,并用Hurst指数预测未来植被覆盖度变化趋势。结果表明:近8年淮河流域地表植被覆盖度总体呈上升趋势,上升率为0.007/a,其中1999年值最低,2004年值最高。植被变化以稳定和轻微恢复为主,更多区域由较低等级的植被覆盖度转变为较高等级植被覆盖度。由Hurst指数预测到未来植被覆盖度变化将保持增加趋势。

Monthly and quarter NDVI were computed respectively by using maximum value composites method and average method with 10-day NDVI of SPOT-4 VEGETATION of Huai River Basin from 1998 to 2005.The vegetation coverage was derived from the dimidiate pixel model.On this basis,the change of vegetation coverage of the past eight years was analyzed from the different point of view.At last,the Hurst index was used to predict the future trend of vegetation coverage.The results show that over the past eight years,the overall vegetation coverage of Huai River Basin were rising.The per annual rate of rise was 0.007.The maximum vegetation coverage was in 2004,and the minimum one was in 1999.The change of vegetation coverage was mainly in stabilization and slight recovery.More areas were changing from the lower level of the vegetation coverage to the higher level one.And it would keep the increasing trend in the future according to the Hurst index.