Abstract: Pinglu Canal project is an important water transportation infrastructure for China’s “New Western Land and Sea Corridor”, and the Youth Hydro-hub is the most downstream node control hub of the canal. Due to the influence of saltwater upstream in the Qinjiang tidal section, reasonable prediction of saltwater intrusion distance is of great significance for understanding the lifespan of Youth Ship Lock and urban drinking water safety. Based on the measured data of the saltwater intrusion upstream in the Qinjiang River Estuary, a prediction model of saltwater intrusion length in the high tide period considering the estuary geometry, tidal action and runoff process was constructed based on the one-dimensional diffusion steady-state equation for saltwater upstream. Then, the influence of runoff and tidal action on the length of saltwater intrusion length in the Qinjiang River Estuary was analyzed. The obtained main conclusion is that when the upstream inflow is Q<100 m3/s, the saltwater intrusion length in the Qinjiang River Estuary during the high tide period after the Pinglu Canal project is L=10~27 km, with an increase of 4.5 km compared to before the project. When the upstream runoff inflow is Q<20 m3/s, the saltwater in the Qinjiang River Estuary will flow upstream to the bottom of the Youth Ship Lock. During the dry season, the minimum discharge of saltwater from the Youth Hydro-hub must reach 20 m3/s when the tidal range of the river estuary is H0>2.5 m.

Key words: waterway engineering; Qinjiang River Estuary; saltwater intrusion length; predictive formula

摘要： 平陆运河工程是中国“西部陆海新通道”的重要水运基础设施，青年枢纽作为运河最下游的节点性控制枢纽，受钦江感潮河段的盐水上溯的影响，合理预测盐水入侵距离对认识青年船闸寿命与城市饮用水安全具有重要意义。利用钦江河口盐水上溯过程的实测数据，基于盐水上溯一维扩散稳态方程构建了考虑河口几何形状、潮汐作用及径流过程的高潮期盐水入侵长度预测模型，并通过径流与潮汐作用对钦江河口盐水入侵长度的影响分析，取得的主要结论为：当径流流量Q<100 m3/s时，平陆运河工程后的高潮位期钦江河口盐水入侵长度L=10~27 km，较工程前增加了4.5 km；当径流流量Q<20 m3/s时，钦江河口盐水将上溯至青年船闸闸下；枯水期，当河口潮差H0>2.5 m时，青年枢纽减盐的最低泄流量须达到20 m3/s。

关键词: 航道工程；钦江河口；盐水入侵长度；预测公式