莱州湾东岸岬间海湾海岸地貌演变过程与影响机制

发布时间：2018-04-14 19:54

本文选题：海岸侵蚀 + 岬间海湾　；参考：《中国科学院烟台海岸带研究所》2017年博士论文

【摘要】：针对莱州湾东部砂质海岸人类活动剧烈、河流输沙变化显著等问题,选取莱州湾东部4个岬间海湾所构成的整体岸段作为研究对象,综合使用野外调查、3S(RS/GPS/GIS)技术、沉积物分析、数字海岸分析、数值模拟和平衡岸线推算等方法,研究最近60年海岸动力地貌演变过程及其影响机制。研究内容主要包括最近60年岬湾海岸地貌演变、人类活动的沉积动力效应以及海岸冲淤动态,以揭示河流入海输沙减少、潮上带土地利用变化和海岸工程对海岸地貌演变的影响机制,查明海岸侵蚀发生的地貌冲淤背景、发展过程和时空差异,并建立最近60年来莱州湾东部砂质侵蚀海岸动力地貌演变差异性分析。主要结论如下:(1)莱州湾东部海岸兼具岬湾和平直砂岸的基本地貌特征。在60年时间尺度上海岸形态特征摆动于两者之间,导致沿岸输沙变化频繁。在自然状态下屺坶岛—石虎嘴岬湾的不稳定性参数值最大(11.15%),其下游的三个岬湾不稳定性依次降低。故输沙减少情况下,屺坶岛—石虎嘴岬湾的海岸侵蚀最强烈,尤以界河口附近岸段最为显著(后退2.31km)。且遮蔽段均较切线段侵蚀调整显著。海岸系统对河流入海泥沙减少的地貌冲淤调整需要30年。入海泥沙减少与否及比例,对岸线调整至动态平衡的时间影响差别不大。入海泥沙量变化对不同岸段影响差异显著,且平衡岸线差别较大。(2)莱州湾东部岸线迁移和水下岸坡冲淤具有非线性的显著特点,呈现冲淤交替的特征。1959-2013年,岸线侵蚀速率波动起伏,以1985年为界先减后增。各岬湾的岸线变迁与整体并不一致。除了三山岛—刁龙嘴岸段一直处于淤积或平衡状态外,其余三个岬湾在十年尺度上岸线演变呈现冲淤交替分布的空间格局。1959-1985年,岸线整体向海推进,同时水下岸坡2m,5m和10m等深线处水深均淤积变浅,淤积面积和泥沙量分别为1.87×108m2和1.15×108m3。1985-2006年,岸线整体侵蚀后退,2m等深线处水深增加,5m等深线处水深基本不变,而10m等深线则淤积变浅,淤积面积仅为5.58×107m2,淤积泥沙量为前期的8%。大部分岸段岸线外侧出现了连续展布的水下侵蚀条带。(3)莱州湾东部海岸埋藏样的沉积类型属于中、粗砂,分选程度中等-好,以正偏、极正偏为主,66.67%源自浅海沉积,而目前浅海及古海滩沉积的出露则表明该岸段近期处于蚀退状态。148个海滩表层沉积物主要属于粗砂、中砂和极粗砂,分选程度以好和中等为主。位于界河口附近的剖面平均粒径最粗,向下游逐渐减小。(4)在河流上游大规模的修建水库,导致莱州湾东岸河流入海泥沙量的减小,显著改变了地貌的冲淤演变。水动力数值模拟结果显示,随着河流入海泥沙量的减少,整体侵蚀作用越来越显著,范围不断扩大,强度不断加大。不同岸段呈现不同的冲淤状态,侵蚀条带主要分布在2—5m等深线之间,且靠近岸河口处侵蚀严重。但是,除了界河口、王河口、刁龙嘴西南等个别地点有较强的侵蚀发生外,2m等深线以浅区域均处于冲淤平衡或轻微淤积状态。(5)莱州湾东部海岸土地覆被变化的总趋势是风沙地、林地和耕地向养殖池及居民地转化。在多年大潮平均高潮线和特大潮高潮线之间形成了一条平行于岸线、宽达数百米,纵向基本连续展布的水产养殖设施带。水动力数值模拟结果显示,风暴潮时岸线附近波高和流速变化显著。随着养殖设施覆盖比例的提高,沿岸侵蚀条带向下游延伸,向外海展宽;岸线附近侵蚀深度和范围均明显增大,水下岸坡闭合水深加大,闭合位置向外海推移。(6)龙口人工岛一期工程改变了屺坶岛-石虎嘴岬湾的上游控制点,导致沿岸输沙速率与方向显著变化。根据一线模型预测结果,界河口东侧岸段,沿岸输沙方向发生逆转(由NE-SW向转为SW-NE向),造成了后方掩护区域的淤积,而下游岸段(界河口东侧至诸流河西南1.5km处)强烈蚀退。利用抛物线模型对静态平衡岸线的模拟结果显示,界河口附近及其西南侧岸线将侵蚀后退;石虎嘴岬角岸段将向海淤进,强烈侵蚀岸段与一线模型预测结果一致。(7)莱州湾东岸海岸地貌冲淤演变具有显著的不稳定性,不同时期、不同岸段分别处于侵蚀后退或淤积前进状态并呈交替式时空分布。受海岸边界条件的控制,再加上风暴潮作用的高频率出现,至少在60年尺度上该段海岸地貌冲淤变化不稳定;在海滩—水下沙坝泥沙交换、岬湾—平直砂岸转换以及水库拦沙、潮上带工厂化水产养殖、大型海岸工程等人类活动的地貌效应共同作用下,最近60年来发生了至少5次岸线进退以及冲淤速率大小的交替,平均10年就发生一次转换,且不同岸段不同步。其未来50年尺度上的海岸地貌冲淤变化趋势为总体侵蚀后退背景下的冲淤交替。
[Abstract]:In the eastern Laizhou Bay sandy coast humanactivity, river sand changes significantly, the overall selection of the eastern Gulf of Laizhou coast of 4 headland Bay as the research object, the integrated use of field investigation, 3S (RS/GPS/GIS) technology, sediment analysis, analysis of digital sea shore, numerical simulation and calculation method of equilibrium shoreline the last 60 years, the research of coastal dynamic geomorphology evolution and its influence mechanism. The research content mainly includes the last 60 years headland Bay coast landform evolution, sedimentary dynamic effect of human activities and coastal erosion and accumulation, in order to reveal the river sediment reduction, the influence mechanism of supratidal zone land use change and coastal engineering on the development of the coastal landforms. Identify the coast erosion landform erosion background, process and the spatial and temporal differences of development, and the establishment of the last 60 years in the eastern Laizhou Bay eroded sandy coastal dynamic geomorphology evolution difference Analysis. The main conclusions are as follows: (1) the eastern coast of the Gulf of Laizhou has the basic features of Cape Bay and straight sand coast. In the 60 year time scale of Shanghai shore morphology swing in between, resulting in Longshore Sediment Transport changes frequently. In the numerical instability of the natural state of Qi Mu Island - Stone Tiger mouth Cape bay the Senate (11.15%), three headland Bay downstream of the instability decreased. So the sediment reduction situation, coastal erosion, Qi Island - Tom Stone Tiger mouth Cape bay the most intense, especially in the field near the estuary coast is the most significant (back 2.31km). And the shield section were cut line erosion adjustment significant. Coast system on river sediment decline the landform erosion and deposition in 30 years. The sediment reduction and proportion, little difference across the line adjusted to the dynamic balance of time. Changes of sediment content on different shore effect was significant, and the difference between equilibrium shoreline (2 larger. The eastern Laizhou Bay shoreline migration) and underwater slope erosion has obvious characteristics of nonlinear, showing erosion alternate characteristics.1959-2013, shoreline erosion rate fluctuations, in 1985 for the sector first decreased and then increased. The headland Bay coastline change and is not consistent. In addition to Sanshandao - Diao longzui bank has been in a deposition or balance, the remaining three headland Bay in the ten year scale evolution of scouring and silting of the shore line in the alternate distribution of the spatial pattern of.1959-1985, the whole coastline advancing to the sea, and the underwater slope of 2m, 5M and 10m were shallow water depth isobath sedimentation, siltation area and sediment were 1.87 * 108m2 and 1.15 * 108m3.1985-2006, the whole coastline erosion, increase at 2m isobath depth at 5m isobath depth and 10m isobath is basically unchanged, siltation shallow, siltation area is only 5.58 * 107m2, the sediment amount for the 8 most coastal. There has been a continuous distribution of lateral shoreline water erosion bands. (3) the sedimentary types in the Gulf of Laizhou belongs to the kind of East Coast buried in sand, moderately sorted - well, with positive bias, very positively skewed, 66.67% from the shallow sea sediment, and the shallow sea and the ancient sedimentary outcrop that the shore in the recent period of erosion.148 beach surface sediments are mainly coarse sand, medium sand and coarse sand, with good degree of sorting and medium. In the field near the mouth of the average diameter of the thick section, gradually reduced to the downstream. (4) in the upper reaches of the river and built large-scale reservoir, resulting in the decrease of Laizhou Bay River the amount of sediment, significantly changed the topography of the fluvial process. The hydrodynamic numerical simulation results show that with the decrease of river sediment supply, the overall erosion becomes more and more obvious, expanding the scope of strength increasing. In different locations have different The erosion and deposition, erosion belt is mainly distributed between 2 5m isobath, and near the shore at the mouth of serious erosion. However, in addition to jiehekou, king of dragon mouth Diao River, southwest of individual place has strong erosion, 2m isobath to shallow areas are in sedimentation balance or slight deposition (state. 5) the general trend of the eastern coast of the Gulf of Laizhou land cover change of sand, woodland and farmland to the pond and residents. In the years of transformation between the tide and mean high tide line super tide high tide line to form a parallel to the coastline, several hundred meters wide, vertical basic continuous aquaculture facilities distribution zone. The numerical simulation results show that the storm surge and wave velocity near the shoreline change significantly. With the increase of the proportion of breeding facilities covering, coastal erosion belt extends downstream to the sea, broadening; near the shoreline erosion depth and range were all increased significantly, The increase of water depth of the bank under the closed, closed position to sea passage. (6) the upstream control point of Longkou artificial island project changed Qi Mu Island - Stone Tiger mouth Cape Bay, resulting in Longshore Sediment transport rate and direction of change. According to the results of a model, jiehekou east coast, Longshore Sediment transport direction reversed (from NE-SW to SW-NE), caused by the rear cover area of the deposit, while the downstream coast (jiehekou east to Zhuliuhe River southwest of 1.5km) strong erosion. Using the parabolic model simulation results of static equilibrium shoreline shows jiehekou near the southwest side of the shoreline erosion and stone; the tiger mouth Cape Coast to sea siltation, strong erosion coast and a model to predict the results. (7) east of Laizhou Bay coastal geomorphological evolution of erosion and deposition has significant instability in different periods, different sections respectively in the back or forward shaped erosion deposition State and alternately controlled by the coast. The temporal and spatial distribution of the boundary conditions, coupled with the high frequency of storm surge occurred, at least 60 years on the scale of the coastal landforms scouring and silting instability; water exchange in beach sand bar sand, Cape Bay - straight sand shore conversion and reservoir, tide with the aquaculture industry, interaction between large coastal engineering human activities such as landform effect, the last 60 years there were at least 5 times and the erosion rate of shoreline and the size of the alternate, an average of 10 years had a conversion, and different locations are not synchronized. The next 50 years on the scale of coastal geomorphology the overall trend of scouring and siltation erosion under the background of the scouring alternately.

【学位授予单位】：中国科学院烟台海岸带研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P737.1

【参考文献】