2000年以来黄河宁蒙河段开河期冰凌洪水特点分析

黄河宁蒙河段开河期冰凌洪水主要集中在3月中下旬,一般由融冰洪水与冰坝洪水组成,其特点主要表现在:凌峰、洪量年际变化大,沿程增加明显,头道拐站易形成多峰,峰型系数较夏汛小,洪水历时较夏汛短,水位表现较夏汛同流量水位高,流速在涨水段慢于落水段。这些特点主要与宁蒙河道形态、水利工程、封河期上游来水及开河期气温、开河形势、封冻期形成的槽蓄水增量大小、沿程分布及其释放程度有关。

Analysis of ice flood characteristics during thawing period at ningxia-inner mongolia reach of Yellow river since 2000

Ice flood during thawing period in the Ningxia-Inner Mongolia reach of Yellow river is concentrated in mid and late March.and usually make up from ice melting flood and ice dam flood. Its characteristics primarily shows the large annual change of ice flood peak and flood volume, obvious increase of that along the river; being easy formation of multi-peak at Toudaoguai station; the ice flood peak coefficient in march being smaller than that in summer, shorter duration compared with summer flood, higher water level of the same discharge than that in summer and slower velocity of runoff in rising segment than that in falling segment. These characteristics principally relate to the river morphology, water conservancy projects, freeze-up period upstream inflow, air temperature in thawing period, river thawing situation, freeze-up period river channel-storage increment volume, along distribution and its release degree.