Abstract: According to climate data of 86 meteorological stations in 1962-2006 in Guangdong Province,the soil daily available water content(AWC) was calculated to simulate the soil moisture balance and to set up the daily drought index(DI),based on the soil moisture balance model.The spatial and temporal variations for the different grade droughts in recent 45 years in Guangdong Province were analyzed.The results showed that: 1) The all-year drought days accounted for 28.7%.The occurrence frequency of light,medium,serious and extreme drought decreased in turn;2) The seasonal variations of the drought course index(DCI) were mainly influenced by precipitation;it showed distinct characteristics of wet season and dry season.3) Both of drought days and DCI increased from 1962 to 2006,which implied that the frequency and severity of drought were rising.4) Both DCI and drought days spatially varied with latitude,which was higher in the South and lower in the North.The DCI and drought days in Lianshan were the lowest in Guangdong,while they were higher in the Leizhou Peninsula and the southeast coast of the Province.5) The DCI in the spring and autumn spatially varied with latitude contrarily.The spring drought was more serious in the South,while the autumn drought was more serious in the North.6) The DCI in autumn was higher than in spring,which implied that the autumn drought was more serious than spring drought in Guangdong province.This study provided references for response to the climate change,exploitation and utilizing of climate resources and planting zoning adjustment.

Key words: Soil moisture balance model, Soil moisture balance model, Soil available water content(AWC), Drought course index(DCI)