长江中游航道的临界归槽河宽

实测资料分析表明,汛后退水过程中,当水位退至82航行基面以上6m时,长江中游水道浅滩开始冲刷,与此对应的河宽称为归槽河宽.长江中游水道归槽河宽存在临界值,当实际归槽河宽大于临界归槽河宽时,水道可能碍航,而当实际归槽河宽小于临界归槽河宽时,航道条件较好.实测资料统计及理论分析表明,沙市—藕池口、藕池口—城陵矶、城陵矶—武汉、武汉—九江临界归槽河宽分别约为1 300～1 500m、900～1 100m、1 500～1 700m、1 800～1 900m,随设计水位及航道尺度不同而有所变化.三峡水库蓄水后,沙量减小,洲滩萎缩,归槽河宽增加,应及时对归槽河宽接近或大于临界归槽河宽水道中的关键洲滩进行守护,防止归槽河宽进一步增加导致航道条件恶化.

Study of critical width of water retaining to channel in middle-reach channel of Yangtze River

Field data show that shoals in the middle-reach channel of the Yangtze River begin to scour when level falls back to 6 meters above navigation baselevel issued in 1982.The river width of 6 meters above navigation baselevel is called width of water retaining to channel(WWRC),and Critical WWRC(CWWRC) exists.When WWRC is greater than CWWRC,the condition of channel may be very bad;while when WWRC is less than CWWRC,the condition of channel is perfect.Analysis based on observed data and theoretical analysis show that CWWRC in Shashi—Ouchikou,Ouchikou—Chenglingji,Chenglingji—Wuhan,Wuhan—Jiujiang is about 1 300-1 500 m,900-1 100 m,1 500-1 700 m,1 800-1 900 m respectively;and CWWRC varies with navigation baselevel and channel scale.After operation of the Three Gorges Project,sediment transportation decreases,which causes erosion of bars and increase of WWRC.When WWRC is equal to or greater than CWWRC,the bars should be protected in time to prevent deterioration of navigation condition.