汉江兴隆水利枢纽下游近坝段水位下降成因及防治对策

Causes and Preventive Measures of Water Level Drawdown Downstream Near the Dam Site of Xinglong Hydrojunction Project on Hanjiang River

汉江兴隆水利枢纽2013年运用以来,坝下游近坝段中、枯水期水位较建坝前发生了不同程度的下降,到2018年枯水位最大下降1.67 m,造成船闸闸槛水深不足,影响船舶顺利过闸。基于对该河段实测水文、地质、河床地形资料分析,对坝下游近坝段水位下降的原因和防治措施进行了研究。结果表明:枢纽的清水下泄和河床床沙易被冲动,使河床平滩河槽冲刷下切和展宽,是造成坝下游中、枯水期水位下降的主要原因。为此,提出了对坝下游近坝段平滩河槽进行护底、修筑潜坝等工程措施来防治河床冲刷并适当抬升河道枯水位,同时建议尽快修建引江补汉工程增加汉江中下游枯水期来水流量,从根本上解决船舶过闸问题和坝下游河道中、枯水期水位下降带来的不利影响。

Since the Xinglong Hydrojunction Project on Hanjiang River was put into operation in 2013,the water level in the middle and dry seasons downstream near the dam site has decreased to varying degrees compared to that before the construction of the dam.By 2018,the dry water level has dropped by 1.67 m to the maximum,resulting in insufficient water depth of the ship lock threshold and affecting the smooth passage of ships.Having analyzed the measured hydrology,geology,and riverbed topography data of the river segment,we looked into the causes and preventive measures of the water level drawdown.Results reveal that the downward erosion and widening of flat riverbed induced by the discharge of clear water and the easily eroded riverbed sand are main causes of the drop of middle and low water levels in the downstream of dam site.We propose some engineering measures such as protecting the bottom of flat beach channel in the downstream near the dam site and constructing submerged dams to prevent riverbed from erosion and to appropriately raise the low water level of the river channel.In the meantime,we recommend to construct water diversion project from the Yangtze River to the Hanjiang River as soon as possible to increase the flow of water in the middle and lower reaches of the Hanjiang River in low water period in the purpose of fundamentally solving the problem of ships passing the gate and the adverse impacts caused by the water level drawdown.