【作者】 王轲道；

【导师】 王建；

【作者基本信息】 南京师范大学 ， 自然地理学， 2005， 博士

【摘要】 论文以位于江苏吕四侵蚀性细沙粉沙质海岸的茅家港岸段为例研究海岸工程影响下的岸滩地貌变化。通过分析吕四海岸的发育历史和动力环境,采用GIS技术对滩面地形图进行了数字化,形成不同时期的数字高程模型,运用剖面对比法、数字高程模型计算分析等方法,并结合实地地貌调查,定性与定量相结合地分析研究茅家港附近滩面在工程建设前后岸滩地貌变化,同时采用物理模型试验进行验证。在此基础上,结合粒度、磁化率和孢粉变化等辅助手段研究滩面的冲淤变化及其机制,并通过数学计算研究分析突堤之间和离岸堤内滩面的淤积趋势。主要结论如下: 1.茅家港工程建成后,两突堤之间滩面淤积,航道位置和深度稳定。突堤西侧堤角的滩面以冲蚀为主。突堤东侧堤角的滩面处于淤积状态。口门以外的滩面处于冲淤不断变化的状态,航道处于自然摆动状态。茅家港岸滩在自然条件下和工程影响下都有春夏季节淤积、秋冬季节侵蚀的季节变化特点。1991.11～1992.12,突堤内落淤百分比为62%,平均淤积速率达0.008476m/月,1992.12～1993.09突堤内落淤百分比仅为21.8%,平均淤积速率仅0.004439m/月,到1993年9月,堤内滩面淤积达到平衡状态。 2.离岸堤工程建造后,离岸堤内的滩面由原来的冲刷状态变为淤积状态。离岸堤内的滩面上越靠近离岸堤的位置淤积效果越好,且由于被淤积而形成了与原始滩面倾向相反的新滩面。 3.粒度、磁化率和孢粉分布和变化与滩面淤蚀动态的一致性。茅家港突堤西侧滩面,沉积物的粒度祖,磁化率大,水动力增强,滩面侵蚀;突堤之间、突堤东侧的滩面沉积物的粒度细,磁化率小,说明水动力弱,滩面淤积。离岸堤内的滩面柱状图的粒度、孢粉和磁化率的分布和变化都表明:离岸堤建成后,3～4年内滩面的淤积达到了平衡状态。 4.细沙粉沙质海岸工程建成后,附近滩面冲淤分布与沙质、淤泥质海岸工程建成后的滩面冲淤分布有所不同,形成特殊的淤蚀形态:突堤的上游滩面冲刷、下游滩面淤积;离岸堤所造成的淤积沙嘴是开始紧靠离岸堤的背后,后来淤积沙嘴又从岸向海、从离岸堤向陆同时淤长。更多还原

【Abstract】 The paper studied changes of beach landform impacted by coastal engineering, by taking example of Maojiagang strentch which lies in Lvsi erosion coast Jiangsu province. We started with analyzing the background of Lvsi coast, applied the GIS technology to make the landform map digitization so as to form the DEM of different period. We applied the method such as the section comparison and DEM calculation and analysis and referred the field survey to study the beach landform change before and after the engineering constructing by using both the qualitative and quantitative methods. At the same time, we applied the physical model to accept it. Based on applying the assistant measure such as the change of grain size, susceptibility and spore powder of the beach sediment, we studied the chance and mechanism of erosion-deposition of the beach surface and used mathematical calculation to analyze the trend of erosion-deposition of the beach surface between the two jetties and inside the offshore breakwaters. We drew the main conclusions as following:1. After the construction was completed, the beach between the two jetties had been filled up step by step. The position of sea-route and the depth is steady. The beach on the west of jetty is on the condition of erosion and the beach on the east of jetty is on the condition of deposition. The beach out of the jetty is on the natural condition of erosion-deposition. The sea-route is in a state of natural sway. The natural change of the bank nearby Maojiagang has the characteristic of seasonal change: the sand surface is filled up in spring and summer and is flushed in fall and winter. The sediment of jetty was in the proportion of 62 percent between Nov. in 1991 and Dec. in 1992, and the average rate of sediment was 0.008476m /month. Between Dec. 1992 and Sep. 1993 the proportion was only 21.8 percent, and the average rate was just 0.004439m / month. The beach surface inside the jetty had got a balance of erosion and sediment until September 1993.2. After the construction of offshore breakwater had been completed, the state of the beach surface outside the offshore breakwater turned from flush to sediment. Nearer the distance to the offshore breakwater is. effects of surface sediment inside the offshore breakwater is the better. and formed the new surface that has course incline with initial surface due to deposition.3. The distributing and change of granularity. susceptibility and spore powder distribution accord with the change of surface sediment dynamic erosion-deposition. With the distance from surface to beach increasing, the granularity of deposition is thicker and the susceptibility augment, the granularity of the sediment inside the jetty is less than the outside and the susceptibility is less than the outside. It reflects that the dynamic condition inside the jetty is weaker than the outside. The granularity of the histogram section and the distributing and change of susceptibility and spore powder inside the offshore breakwater show a 3 or 4 gyration, it indicates that the beach surface sediment has got a balance condition until 3 to 4 years after the offshore breakwater was completed.4. The distribution of the beach surface nearby the engineering after the completion of silty coast differs from the distribution that after the completion of sandy and muddy coast, it formed a special configuration of erosion-deposition: Upriver of the jetty has been flushed and the downriver has been filled up after the silty coastal engineering was completed. At the beginning, the sediment headland caused by offshore breakwater was closed to the offshore bank and thus then extended both from land to sea and from sea to land.更多还原