Study On Characteristics Of River Ice Evolution And Numerical Simulation Of The Yellow River (Inner Mongolia Reach)

River ice is the key factor on the development of cold region water resource. Due to the specific climate characteristics, geographic location and stream orientation, the Yellow River (Inner Mongolia reach) is the most serious and hotspots area of ice flood. The ice jam and ice dam are main reason of ice flood in the Yellow River according the years of data statistics and field observation. In this paper, the Yellow River (Inner Mongolia reach) was choosed as research reach, according to the field observation of river ice process in the 2012-13 and 2013-14 winters, the characteristics of river ice evolution were analysised. The river ice process was simulated by using DynaRICE river ice model, combined the thermodynamic process, border ice and ice cover development theory to discuss the river ice formation, transport, accumulation and ice cover progress.The Sanhuhekou river bend ice process was simulated under consideration thermodynamic and hydrodynamic factors.1) The ice period become short and ice thickness become thin on the effect of warm weather. Ice dam occurs at the lower reach during freeze up period. While the middle reach become the dangerour reach due to the low are temperature and storage release when the upper and lower reach are breakup at first.2) The fisrt ice flow site is always located at high latitude and low air temperature middle reach. The ice may flow when the air temperature on the below of-5℃. There is a negative correlation between ice concentration and air temperature, and ice concentration has relationship with ice jam condition and bed bathymetric as well. The ice flow period and speed are affected by air temperature. The speed is low with alternation of air temperature, compared with the middle and lower reachthe upstream speed is fast, the freeze-up speed is fast at the begin of winter and become slow later. The sequence of freeze-up is from downstream to upstream. The sequence of freeze-up and breakup is opposite.3) The surface ice transport is affected by the water drag and gravity in the flow direction, the secondary current on the effect of surface ice transport can be neglected. Surface ice will move along the main flow and may jam at the exist of river bend. The upstream ice concentration, flow condition and bed bathymetric affect the location of ice bridge.4) Evaporative heat transfer φe and conductive heat transfer φc, are the main factors on the surface heat exchange with atmosphere, which are affected by the air temperature and wind speed. The border ice may form at the area of water velocity is lower than 0.4m/s. border ice type and ice cover progression mode are controlled by the flow condition and thermal condition. The growth of ice cover thickness increase fast at the initial time, and become slow at the end of time. The decay of ice cover thickness is quickly under the effect of thermal and flow condition.5) The Sanhuhekou river bend ice process was simulated by using ice dynamic and thermodynamic model. The results shows the formation of border ice will decrease the capacity of surface ice transport, ice bridge will form at the river bend with great curvature when upstream ice concentration is high. Ice cover will progress at this area, and open water appears at the downstream of ice bridge.