黑龙江上游开江期河道特征对流冰速度的影响

The influence of river characteristics on drift ice velocity during the opening period of the upper Heilongjiang River

为探究黑龙江上游江段开江期流冰速度沿程变化规律和运移过程,通过抛投微型冰浮标定位器进行流冰追踪试验,分析黑龙江干流开江期流冰速度分布特征及河道形态对流冰速度的影响规律。结果表明:2019年开江期距黑龙江干流源头69~692 km河段流冰速度分布为0.79~3.56 m/s,平均速度为1.65 m/s,流冰速度与河道宽度、河道弯曲系数呈负相关关系;在弯曲河段、江心岛河段和弯曲分汊型河段流冰速度降低趋势明显,且河道特征对流冰速度的影响依次减弱。流冰速度沿程分布规律可为冰坝预测及预防凌汛灾害提供数据支持,研究成果对寒区河流治理具有十分重要的意义。

The drift ice is easy accumulate and form to ice dam which will block the river channel and reduce the river's water carrying capacity during freezing and melting period.Once the ice dam is formed,the rapid rise of water level in the short term will lead to ice flood danger.Ice flood disasters seriously affect the safety of the waterway,the stability of hydraulic structures,the ecological balance of the river,etc.According to statistical analysis,a relatively serious ice dam formed in the upper reaches of Heilongjiang River every three years and the location was not fixed.Meanwhile,it is very difficult to understand and predict the occurrence and severity of ice dam because of the chaotic nature of ice dam formation and its impact on river hydraulic conditions.In view of this,it is hoped to provide support for the prediction of ice dam in Heilongjiang River by studying the velocity variation of drift ice in the upper reaches of Heilongjiang River during ice break-up season.In the past,more studies were conducted on the process of river ice creation and removal,river opening forecasting,and ice damage risk assessment which with prototype observation,numerical simulation and theoretical models serving as the predominant research approaches.The quantitative monitoring of drift ice movement is highly challenging,and the early research on ice movement and velocity are often watched visually by employees.With the development of technology,the drift ice velocity values of river sections can be obtained by relying on acoustic Doppler radar,particle image velocimetry,image measurement techniques and satellite remote sensing technology.The progress of technology supports the accurate measurement of the ice velocity and transmission process along the river,which is lays a solid foundation for the assessment of river ice dynamics and ice flood prediction.The application of GPS positioning technology in the measurement of glacier movement speed and sea ice drift speed was quite mature.Using this method,the drift ice tracking test was conducted by the micro buoy locator to investigate the changing pattern of drift ice velocity along the river channel and transport process in the upper reaches of Heilongjiang River during ice break-up season.The plane positioning accuracy of the micro buoy locator was less than 10 m that used the positioning mode of"BDS+GPS+BTS"and returned the time,longitude,latitude,speed and speed direction information at an interval of 10 s.Then,the drift ice velocity can be accurately calculated through the position information of two adjacent time nodes of the mini-buoy locator.The results show that the velocity of drift ice ranged from 0.79 m/s to 3.56 m/s,and the mean velocity is about 1.65 m/s in the upper reaches of Heilongjiang River during ice break-up season.In addition,there is a negative correlation between the velocity of drift ice with the river width,and the specific performance was that the velocity of drift ice increases at the narrow part of the river channel and decreases at the wide part of the river channel.Furthermore,the velocity of drift ice decreases near the entrance and exit of the bend which verified by the first bay reach of Heilongjiang River,because it is easy to form spiral flow movement under the action of centrifugal force when the drift ice flows through the bend.On this basis,the application prospect of micro buoy locator in Heilongjiang River ice flood prevention is prospected.