Precipitation, which is the dominant water resources, is sufficient in subtropic hillyland in Hunan Province. A great amount of meteorological data during 1960~2000 and irrigation data during 1989~2000 in paddyfield are analyzed. The results show that the water requirement of the paddyfield is a little more than the rainfall in the whole growth period. During the 1st ten days to the 9th ten days which is mainly corresponding to the growth period of early rice, the water requirement can be sufficiently met by rainfall, however, from th...