宁波镇海沿岸岸滩演变分析

基于1959、1979、2010、2013年4个年份的水深资料,采用地理信息技术,研究了1959—2013年间宁波镇海沿岸海域的岸线变化、特征等深线分布变化及剖面变化,并定量计算了水下岸坡的冲淤变化.结果表明,在这54 a间,岸线持续向海推进约3～5 km,0、3、5 m等深线总体上也向海推进,幅度约330～5 600 m;但由于0 m等深线的推进速率小于岸线,因此干出滩面积锐减.相应的,不同时段水下岸坡的淤积速率分别为0. 46、2. 82、14. 14 cm/a,说明该水下岸坡经历了冲淤基本平衡—轻微淤积—较快淤积的调整过程.结合实测水文泥沙资料,探讨了水下岸坡的冲淤原因和动态趋势,得到了杭州湾南岸大规模围垦工程会维持并加快水下岸坡淤积的结论.

Analysis of the coastal evolution along Zhenhai, Ningbo

Based on a four-year data of water depth in 1959, 1979, 2010 and 2013, the GIS technology is applied to study the variation of coastline, isobaths, and seabed profiles during the period of 54 years from 1959 to 2013 along the coast of Zhenhai, Ningbo. Moreover, the erosion deposition variation of the underwater slope is calculated. The results indicate that the coastline continuously moved seaward about 3-5 km, and 0 m, 3 m, 5 m isobaths generally moved seaward about 330-5 600 m in the 54 years. However, the movement rate of 0 m isobath was less than that of the coastline, resulting in a sharp shrink of the dry shoal. Accordingly, the deposition rate in the underwater slope is 0.46 cm/year from 1959 to 1979, 2.82 cm/year from 1979 to 2010, 14.14 cm/year from 2010 to 2013, illustrating that underwater slope experienced an adjustment process from basical stability to slightly deposition and then rapidly deposition. With the hydrological and sediment data of field observation, the deposition factors and trends were discussed. It is concluded that the large scale reclamation projects in the south coast of Hangzhou bay will maintain or even accelerate the deposition rate on the underwater slope.