Abstract:

In view of droughts development and evolvement of Hubei,Hunan,Jiangxi,Anhui,Jiangsu provinces along the MiddleLower Reaches of the Yangtze River in spring and summer 2011,based on MODIS images from April to August of 2011,normalized difference vegetation index(NDVI) from 16days synthetic data MOD13A2 was used to build and calculate anomaly vegetation condition index (AVCI),which had been divided into five levels to monitor droughts.8 phases of drought spatial distribution of the five provinces along the midlower reaches of the Yangtze River has been gotten based on anomaly vegetation condition index(AVCI),which showed the evolution process of droughts in spring and summer，2011.The results showed that the AVCI index could effectively monitor spring and summer droughts in the five provinces.During the entire monitoring period,AVCI of most parts in the five provinces was low and turned up widespread continuous drought.It was clear that the droughts had the trend of aggravatedreducedaggravated again from the sequence change maps of AVCI in these areas. Spring drought was mainly located in mideast of Hubei, midsouth of Anhui，southern Jiangsu，northeastern Hunan, northern Jiangxi,while summer drought was spread over a relatively large area in the five provinces.It was found that spring drought was heavier than summer drought,and drought was more serious in plain area