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32 km 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 55 km 处, 顶托影响高度达 21 14 m。

The enco unter betw een the flo od fr om t he mainstr eam and its tributaries can easily lead to the backw ater phenome2 non, causing poo r drainag e of river channel f loo ds and g reatly incr easing the floo d contro l risk of t he riv er co urse. Taking the backwater effects o f the second Songhua riv er f loo d on the Nen riv er floo d as the pr oject backg round, we ado pted the one2dimen2 sio nal hydro dy namic method to simulate and calculate the backwat er effects o f t he second Song hua river floo d on the Nen river floo d under differ ent flood combinations, and further quantitat ively ana lyzed the affected distance and heig ht based on the model simulatio n r esults. The r esults show ed that the affected distance of Nen river due to t he seco nd Songhua river floo d is relativ ely complex , and is closely r elated to t he relativ e sizes of the floo ds from the t wo rivers. When the flo ods magnitudes in the tw o riv2 ers a re equal, the affected distance is abo ut 32 km aw ay fr om the Sancha est uar y. The g reater the flo od in the second So ng hua riv er, the g reater the af fected distance and height. U nder the combination of 10% fr equency flo od in Nen riv er and 2% fr equency floo d in the second Song hua river, the max imum affected distance of Nen riv er is 55 km aw ay f rom the Sancha est uar y, and the affected height r eaches 21 14 m.

国家自然科学基金( 51709033; 51579027) ; 国家重点研发计划( 2016YFC0402203)