2012年宁蒙河段洪水特点及对河道的影响

Characteristics of Floods in Ningxia-Inner Mongolia Reach in 2012 and the Effect on the Channel

利用实测资料分析了2012 年黄河上游洪水的水沙特点和洪水演进、传播特性以及洪水对河道冲淤的影响,结果表明：2012 年黄河上游洪水水量大、沙量小、漫滩严重,洪水传播速度慢,洪水峰型沿程有所改变;洪水期河道冲淤调整剧烈,整个宁蒙河段河槽冲刷1. 916 亿t,滩地淤积量达2. 032 亿t,冲刷以中粗沙为主.洪水对河道排洪能力的恢复作用显著,洪水后内蒙古河段代表水文站同流量水位下降0. 43 ～0. 63 m,平滩流量增大了201 ～ 588 m^3 / s.漫滩洪水对宁蒙河段河槽的塑造作用较大,建议充分利用大漫滩洪水维持宁蒙河道的长期排洪排凌能力.

This paper analyzed the water and sediment characteristics,flood process,and the flood depositing and eroding effect on river of flood in2012. The result shows that this flood has the characteristics including large volume of water,a little amount of sediment,high flood submergence degree,small propagation velocity and flood wave tape change. The flood effects the Ningxia-Inner Mongolia reach evidently: During the flood,there is 1. 916 × 108 t sediment eroded in channel and 2. 032 × 108 t sediment deposited in the floodplain. The size of most sediment eroded is between 0. 025 mm and 0. 1mm. After the flood,the water level with same discharge of typical hydrologic stations reduces 0. 43 ~ 0. 63 m and the bankfull discharge increases 201 ~ 588 m3/s. The flood in 2012 shows that overbank flood is very important in Ningxia-Inner Mongolia reach modeling. So we should take full advantage of overbank flood to maintain the longterm flow capacity of the reach.