基于一维水动力模型的洪水顶托影响分析

Analysis of backwater effects of flood based on one-dimensional hydrodynamic model

干支流洪水遭遇易发生顶托现象,导致河道行洪不畅,极大增加了河道防洪风险。以第二松花江(简称二松)洪水对嫩江洪水的顶托作用为工程背景,采用一维水动力学方法模拟计算不同洪水组合下嫩江受二松洪水顶托情况,并基于模型模拟结果进一步量化分析嫩江受顶托距离、顶托程度等。结果表明:嫩江受二松洪水顶托距离情况较为复杂,与两江洪水的相对大小密切相关,两江洪水量级相当时,顶托距离为距三岔河口32km左右;二松洪水相对越大,受顶托距离越远且顶托程度越大;在嫩江10年一遇、二松50年一遇洪水组合下,嫩江受顶托最远到达距三岔河口55km处,顶托影响高度达2.14m。

The encounter between the flood from the mainstream and its tributaries can easily lead to the backwater phenomenon,causing poor drainage of river channel floods and greatly increasing the flood control risk of the river course.Taking the backwater effects of the second Songhua river flood on the Nen river flood as the project background,we adopted the one-dimensional hydrodynamic method to simulate and calculate the backwater effects of the second Songhua river flood on the Nen river flood under different flood combinations,and further quantitatively analyzed the affected distance and height based on the model simulation results.The results showed that the affected distance of Nen river due to the second Songhua river flood is relatively complex,and is closely related to the relative sizes of the floods from the two rivers.When the floods magnitudes in the two rivers are equal,the affected distance is about 32 km away from the Sancha estuary.The greater the flood in the second Songhua river,the greater the affected distance and height.Under the combination of 10%frequency flood in Nen river and 2%frequency flood in the second Songhua river,the maximum affected distance of Nen river is 55 km away from the Sancha estuary,and the affected height reaches 2.14 m.