Abstract: Meteorological indicators of early rice flood are recognized to be of realistic importance to the disaster monitoring, prewarning and assessment of early rice flood. Taking early rice in Hunan Province as research object, 385 flood rainfall amount data samples from 9 early rice flood disaster sample sets based on different rice growth stages (transplantingjointing, bootingblooming, milkmaturity) and flood levels (light, moderate, severe) were built in this paper, integrating daily precipitation data (1961 to 2010) from 68 meteorology stations, flood disaster historical data and phenophase data in Hunan Province. K-S test and Student’s tdistribution were employed for the goodnessoffit test and parameters determination, and thus, rainfall thresholds for flood levels were determined based on the confidential intervals of 9 sample sets, and verified by independent samples. Afterwards, temporalspatial characters of early rice flood disaster in Hunan Province were analyzed based on the constructed flood level indicators and ArcGIS. The thresholds of early rice flood disaster were 129, 154 and 241 mm for light, moderate and severe floods in transplantingjointing stage, 135, 170 and 260 mm in bootingblooming stage, and 145, 190 and 295 mm in milk-maturity stage, respectively. Rice flood level indicators were detected to be basically consistent with the historical occurrence levels of rice flood disasters, according to the verification results. Total flood disaster frequency of early rice showed an increasing tendency since 1961, and furthermore, severe floods mainly located in northern Yueyang and southern Chenzhou. South and east regions of Hunan were detected with high frequencies of flood in transplantingjointing. Flood in bootingblooming stage mainly happened in east and central regions of Hunan, while milk-maturity flood occurred mainly in the north region of Hunan. Considering the frequency and intensity of flood, early rice flood disasters were most serious in the 1990s in Hunan. Central Hunan and east to south region of Hunan were the floodprone area during transplantingjointing and milk-maturity stage respectively, in recent 10 years.

Key words: enzyme activity, calcium, abscisic acid, photosynthesis, cucumber seedling