河道特征对黑龙江上游冰坝生消影响

The influence of riverway characteristics on the generation and dissipation of ice dam in the upper reaches of Heilongjiang River

为探究黑龙江上游典型河段不同河道特征与冰坝形成的相关性,在2019年开江期进行了GPS追踪试验,观测开江期流速变化及流凌阻塞程度,并采用多元回归方法建立典型河段河道特征与冰坝生消相关的预报模型。试验结果表明:黑龙江上游不同河段开江期流速呈现先减小后增大的趋势,所得流速变化可以反映开江期各河段流冰阻塞情况,低流速区域与冰坝易发河段契合良好。将典型河段预报结果与实际冰情对比,结果表明在“武开江”条件下,河道比降区间为2‰~3‰,河道弯曲系数处于2.0~3.0之间,河道突缩宽窄比超过3.0的河段易形成冰坝。与传统经验统计预报模型相比,河道特征回归模型优先考虑河道特征元素,预报精度为85%,更为准确地模拟了黑龙江上游各河段在“武开江”期间的冰坝发生概率。

In order to explore the correlation between the characteristics of river courses and the formation of ice dam in the typical reaches of the upper reaches of the Heilongjiang River,the GPS tracking test was carried out during the ice break-up period in 2019.By this method,the velocity of ice/water or the process of ice dam can be obtained.With this,the multiple nonlinear regression method was used to establish the prediction model of the characteristics of typical river courses and the ice dam generation and dissipation.The results show that the velocity decreased first and then increased with the development of river course to downstream in the upper reaches of the Heilongjiang River.The variation of velocity can be used to feed back the flow ice blocking situation at each reach and low velocity was good agreement with the ice dam prone reach.By comparing the prediction results with the actual ice conditions,showed the ice dam is easy to form in the river reach with gradient of 2‰~3‰,bend coefficient of 2.0~3.0,and width to narrow ratio of sudden contraction of river channel exceeding 3.0 that during the mechanical break up.Compared with the traditional empirical statistical prediction model,the regression model of river characteristics gives priority to river characteristic elements,and the prediction accuracy reaches 85%.It more accurately simulates the occurrence probability of ice dam in the upper reaches of the Heilongjiang River during the mechanical break up.