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松花江 (哈尔滨江段 )、嫩江 (江桥站 )洪水可划分成 5个等级。第 1级为无洪水 ,又可分为2个副级 ,即 1a级为中水 ,1b级为枯水 ;第 2级为警戒洪水 ;第 3级为一般洪水 ;第 4级为大洪水 ;第 5级为特大洪水。各级划分是采用流体力学能量方程 ,位能与动能之和用E指数表示 ,再将E值按P -Ⅲ型分布将其密度函数转换成Z指数 ,按Z值正态分布特点划分洪水等级。松花江在98年中共发生过 19次洪水 ,嫩江在 47年中共发生过 10次洪水 ,可见松花江洪水次数远高于嫩江洪水次数。 90年代这两江洪水有多发趋势。
Songhua River (Harbin section), Nenjiang (Jiangqiao station) flood can be divided into five levels. Level 1 is non-flooding and can be divided into 2 secondary levels, namely, level 1a is water, level 1b is low water, level 2 is alert flood, level 3 is general flood, level 4 is flood, Level 5 is a catastrophic flood. At all levels, the hydrodynamic energy equation is used. The sum of potential energy and kinetic energy is expressed by E index, and then the E value is converted into Z index by P-Ⅲ type distribution. According to the normal distribution of Z value, the flood level . In the Songhua River, there were 19 floods in the CCP in 1998, and 10 floods occurred in Nenjiang in 47 years. The number of floods in the Songhua River is much higher than that of the Nenjiang River. In the 1990s, there was a trend of frequent floods in these two rivers.