提出了估算大桥对河道防洪影响的水力学方法，采用这一方法，可以在河道地形和水文资料缺乏的情况下，估算出中、小型河道建桥后桥址上游水位壅高值和壅水范围。具体水力学方法包括：断面流量模数法、宽顶堰淹没出流法、局部水头损失法和恒定渐变流法。应用这些方法，成功地进行了洪湖市汉洪公路新滩东荆河大桥对桥址上游河道防洪影响的计算分析。 Proposed a hydraulic method to estimate the impact of the bridge on the river flood control. By this method, it is possible to estimate the water level 壅 and 壅 of the upstream of the bridge after the bridge is built . Specific hydraulic methods include: modulus of flow section method, wide crested weir outflow method, local head loss method and constant gradient flow method. Applying these methods, we successfully calculated and analyzed the influence of Dongtan Jinghe River Bridge on the Hanjiang River in Honghu City on flood control of the upper reaches of the bridge.