大型工程综合影响下徐圩海域近岸海床演变特征分析

Analysis of the nearshore seabed evolution characteristics in Xuwei sea area under the comprehensive influence of large-scale engineering constructions

随着旗台防波堤、徐圩防波堤、灌河口导堤等工程建设完工,连云港—徐圩海域海床演变由自然演变向工程条件下的演变转变,灌河口沙嘴的稳定对徐圩航道建设至关重要。基于连云港—徐圩海域地形测量资料,采用地形对比分析法和潮流数学模型分析等方法开展大型工程综合影响下徐圩海域海床演变分析。研究表明:大规模工程建设以来,工程附近海域地形调整明显,其中近岸工程掩护区内海床淤积,2 m浅滩持续向外海淤长,防波堤和导堤的堤身外缘及堤头附近局部冲刷,2013—2018年期间地形冲淤幅度达到最大;2018年以后,工程海域海床仍处于调整过程中,但地形冲淤幅度和等深线变化速率均有减缓;灌河口沙嘴向外淤积速率较自然演变期间有所增大,但2018年以后,沙嘴附近较大风浪的发生频率低,沙嘴总体保持稳定。研究成果为大型海岸工程对周边海域影响评估提供了重要的参考和借鉴。

With the completions of large-scale construction projects such as Qitai embankment,Xuwei embankment and Guanhekou guide dike,the seabed evolution in the Lianyungang-Xuwei sea area has changed from natural evolution to the evolution under engineering conditions.In particular,the stability of the Guanhekou sand spit is very important to the Xuwei Channel.Based on the analysis of terrain comparison and tidal mathematical model by topographic data from the sea area of Lianyungang to Xuwei,the seabed evolution analysis in Xuwei sea area under the comprehensive influence of large-scale engineering was carried out.The results show that since the construction of large-scale engineering,the terrain of the sea area near the engineering has been significantly adjusted.The seabed near shallow beach at the constructions has silted up and the area of 2 m-shoal continues expanding to the open sea,and the seabed at the outer edge and head of the embankment and guide dike was scouring.Especially during the period from 2013 to 2018,the amplitude of terrain erosion and sedimentation reached its maximum.After 2018,the seabed in the engineering sea area is still in the process of adjustment,but the amplitude of terrain erosion and sedimentation and the change rate of isobath have slowed down.The outward rate of sedimentation in Guanhekou sand spit has increased compared with the natural evolution period,but since 2018,the frequency of large waves near the sand spit has been low,and the sand spit has remained stable overall.The results provide important reference and inspiration for the evaluation of large-scale coastal engineering in the surrounding sea areas.