| In the current context of climate change, warming and drying trend in South obvious trend for increased drought. Using yield and growth period data of 174 counties in South China (includes Guangdong and Guangxi province), drought index of each growth period of early rice was calculated by daily meteorological drought indicator (DI). drought disaster evaluation model was constructed and temporal-spatial characteristics of the drought disaster was analyzed in the paper. Main results are:(1) Based on the DI, recent 30 years (1981-2010) average drought days frequency of all level in Guangdong and Guangxi region is 26.0%, where light, middle, severe and extreme drought days accounts for 12.3%,8.1%,4.2% and 1.4% respectively. (2)Drought days of each level in non-flood season (October to March) are more than flood season (April to September), and Guangxi is more than Guangdong. (3)The most dry 5 years in recent 50 years in Guangdong and Guangxi region are 1963,1991,2004, 2009 and 1977. (4)According to linear trends analysis, rainfall and monthly drought index(MI) from January to September mainly show increasing trend, and drought days of each level mainly show decreasing trend, where increasing trend of MI and decreasing trend of drought days of each level in July are statistically significant (a=0.1); while rainfall and MI from October to December mainly show decreasing trend,and drought days of each level mainly show increasing trends, where decreasing trend of MI and increasing trends of middle and severe drought days of November are statistically significant (a=0.05). (5)Stations of increasing and decreasing trends of annual drought days account for 60% and 40% respectively, where 11% stations are statistically significant over 0.1 level. Sations with statistically significant increasing trend of drought days of each levels are mostly in Guangxi Province, while stations with statistically significant decreasing trend of drought days are in Guangdong Province,indicating that the overall pattern that drought in Guangxi is more severe than in Guangdong may further aggravate in the future. (6)Based on the drought index of each growth period, average drought year frequency of early rice in recent 30 years (1981-2010) in South China is 10.4%, where light drought accounts for main part, medium and above almost never. Mean yield reduction rate of drought is 0.82%. Drought disaster mainly occurs in transplanting-tillering stage of early rice. (7) Spatial distribution of early rice drought frequency and yield reduction rate was high in west and low in east in Gguangdong and Guangxi region. High incidence region of drought spreads in the area from southwest Guangxi to Leizhou Peninsula of Guangdong Province, where the drought frequency was 20%-50%, and yield reduction rate was 1%-3%. (8) The driest 5 years of early rice in recent 30 years in South China was 1991,2002,1998,1999 and 2003. Drought disaster of early rice in South China tended to increase without statistical during recent 30 years. Those stations where drought disaster of early rice tended to increase significantly assounted for 10%, distributing in north and coastal region from Beibu Gulf to west Guangdong. (9)Stations that drought of early rice in Guangdong and Guangxi region tend to intensify account for about 75%, including transplanting-tillering stage and tillering to jointing stage drought tends to enhance the site more. This study can provide the relevant departments to carry out disaster prevention and mitigation work, provides the basis for tackling climate change. |
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