珠江三角洲口门近期淤积及其对港口航道的影响

Recent Silting in Estuaries and Its Impacts on the Harbours and Channels in the Zhujiang Delta

近20a珠江三角洲口门的淤积加速与水沙分配比的变化、河道冲刷、口门延伸等因素有关。主要港口和航道的自然淤积速率和疏浚后的回淤速率,均以伶仃洋西岸的中山港、九州港为最大,疏浚后的半年或一年半时间便全部回淤。深圳港和珠海港的自然淤积速率最小,分别为0 5～1 4cm/a和1 8cm/a。

During the recent twenty years,in the Zhujiang Delta the flow ratio and stream load ratio increase resulting in the transportation of water and sand eastwards.The river channels in braided river region tend to erosion.The estuaries are extending towards sea and the gradient of river channel is becoming smaller and smaller,resulting in the acceleration of silting process in estuaries especially in the eastern estuaries.In this paper,it was showed that the sea area of Lingdingyang estuary reduced obviously,the ratio between runoff and tidal current increased,the deposition rate increased,the shallows extended and the plain advanced towards sea in the Zhujiang Delta.Silting in estuary impacted on the harbours and channels heavily.The deposition rate in the major harbours after dredging up was larger than that of natural deposition.The silting in the harbours of west coast of Lingdingyang was serious especially.In general,the natural deposition rate was 2～5 cm/a,while the deposition rate in channel after dredging up was larger,such as 120 cm/a in Zhongshan harbour,53 cm/a in Jiuzhou harbour,30～60 cm/a in Huangpu harbour and 27～36 cm/a in Shenzhen harbour.The natural deposition rate was smaller in Shenzhen harbour and Zhuhai (Gaolan) harbour,0.5～1.4 cm/a and 1.8 cm/a respectively.