汶川地震灾区归一化植被指数变化监测分析

Normalized vegetation index analysis in Wenchuan earthquake areas

提取归一化植被指数合成旬最大植被指数,研究地震重灾区域的植被状况。结果表明:1)盆地西部和北部山区,植被在4月下旬到5月底呈现自然生长规律,并且存在一条以旬最大植被指数为标记的稳定边界线来区分盆西山区和盆地农田;2)2008年地震前期,4月下旬的旬最大植被指数好于5月上旬,地震发生的5月中旬,旬最大植被指数在成都平原、德阳和阿坝州交界的山区明显减小,5月下旬,大部分区域旬最大植被指数都在减小;3)2009年5月中旬的旬最大植被指数是最好的,5月下旬,盆地中的旬最大植被指数值减小;4)地震使得在盆西山区和盆地农田之间通过旬最大植被指数表征的稳定边界被破坏。

Normalized difference vegetation index （NDVI） which was extracted from MODIS/EOS data was used to synthetize the ten days maximum NDVI and then vegetation of heavy disaster areas in earthquake was analyzed. Results showed that vegetation in west and northern mountain areas of Sichuan basin grew naturally and there was a stable boundary which could distinguish western mountain areas of basin from farmland areas labeled by ten days maximum NDVI during the late April to the end of May in 2007 that before the earthquake. Before the earthquake in 2008, ten days maximum NDVI in late April was better than that in early May. In middle May when the earthquake occurred, ten days maximum NDVI was significantly reduced in the junction mountain areas at the Chengdu plain and Deyang and Aba prefecture, but in the late May, ten days maximum NDVI was reduced in basin. In May 2009 the middle ten maximum vegetation indexes were the best; in late May, the basin ten maximum vegetation index values decreased. The three years data showed that the stable boundary between the western mountain and farmland areas in basin labeled by the ten days maximum NDVI was destructed