Distribution of rainstorm centers and processes under different weather systems in Haihe River Basin

Based on the rainfall data in Haihe River Basin from 1955 to 2007,the distribution of rainstorm centers and processes under different weather systems was investigated by means of the GIS technology and the statistical methods.The results show that the rainstorm centers of the regional or basin-wide rainfall are mostly located in Luanhe River sub-basin and the least in the Yongding River sub-basin.Rainstorms often happen simultaneously in different sub-basins,mainly in adjacent sub-basins.Cyclone most frequently causes the regional or basin-wide rainstorms in Haihe River Basin.The weather systems have no significant impacts on the coincidences of rainstorms happened among different sub-watersheds as well as in the whole watershed.Most rainfall concentrates in the prior or middle periods.The antecedent type is the most happened rainstorm type for all kinds of heavy rain under weather systems of shear line,high-altitude trough,Mongolia cyclone,north-east cyclone,northeast cyclones and Yellow river cyclone.Both the weather systems of typhoons and Jianghuai cyclone give priority to the mid-term rainstorm type.