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通过无人机遥感、岸滩监测剖面、监测桩和沉积物粒度分析等手段研究了东海岛东北部典型岸段短期冲淤变化特征。结果表明,研究区岸线在一年半的时间内呈现后退趋势,侵蚀严重区域岸线平均后退约10m;岸滩夏季年度变化以侵蚀为主,侵蚀严重部位主要位于低滩,最大下蚀可达1m以上;半年度剖面监测结果显示,岸滩季节性变化明显,存在冬淤夏冲的特征;受风暴潮的影响,岸滩在2014-06—09发生严重侵蚀,部分区域后滨沙丘后退约20m;沉积物平均粒径分布的区域差异表明,沉积物有沿岸向北和向陆一侧运移的趋势。风暴潮、虾池排污和灯塔是影响东海岛典型岸段冲淤的主要因素。 相似文献
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人工岛作为一种新兴的海岸工程, 它的建设所引起的岸滩冲淤和防护问题日益受到人们的关注。本文以海南万宁市日月湾人工岛为例, 通过4期实测海滩剖面数据和多时相遥感影像, 分析了冬季波浪与人工岛联合作用对日月湾海滩冲淤变化的影响, 并结合海区波况, 探究了海滩冲淤变化机理。研究表明, 日月湾海区冬半年的平均有效波高与波浪周期明显强于夏半年, 且波浪强度整体上呈现逐年上升的趋势, 但在人工岛建设前后变化幅度较小; 人工岛建设对海滩地貌变化有强烈影响, 海滩呈现出岛后淤积而两侧侵蚀的显著特征, 岛影区海滩不断淤积, 岸线向海淤进达200m, 甚至可能与人工岛相连形成连岛沙坝, 人工岛后两侧海滩侵蚀, 岸线向陆一侧蚀退最大距离达50m; 海滩在冬季波浪和人工岛共同影响下, 岸滩自北向南依次表现为稳定、侵蚀、淤积、相对稳定、略有侵蚀或淤积、侵蚀、淤积的冲淤变化特征。 相似文献
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根据1963年、1980年、1984年、1997年的历史地图和数字影像图以及2002年、2003年的现场岸滩地貌和岸线测量结果,分析了绣针河口附近岸滩现代岸线的变迁特征,并根据岸滩冲淤演化的特点,将岸滩分为5段,结果显示:东潘家村以北的沙丘海岸目前处于侵蚀后退状态,平均蚀退速率为6～8m/a;东潘家村至岚山头岸段为基岩海岸,除人类活动影响的区域外,岸滩变化是轻微的:1970年至1974年间低潮线后退40～100m,在岚山头岬角以西的王家庄沿岸,从1963年到1984年,海岸线后退了360～540m,岚山港建港以后,海岸遂稳定在现今人工海堤附近;绣针河口区河口海岸的动态变化主要受人类活动的影响;绣针河口至大新庄岸段主要为堆积性岸段;大新庄至韩口主要为侵蚀性岸段,自1963年至今一直处于侵蚀后退状态。修建人工堤坝和挖沙是研究区内人类活动对岸滩影响的主要形式,人工堤坝的修建在一定程度和一定范围内有利于海岸线的稳定,而挖沙将直接导致和加剧海岸的侵蚀。 相似文献
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为保护亚龙湾砂质海岸及其生态系统,文章采用2016年和2019年的监测数据以及2008年的历史数据,依据相关技术标准和方法,从岸线后退速率和岸滩下蚀速率2个方面综合评价亚龙湾砂质海岸的侵蚀状况和侵蚀强度,并分析其原因。研究结果表明：亚龙湾砂质海岸存在持续性较强且较严重的海岸侵蚀;2008-2016年岸线后退速率和年均土地损失面积分别约为-1.00 m/a和2 080 m2,2016-2019年岸线后退速率和年均土地损失面积分别约为-1.80 m/a和9 836 m2,亚龙湾海岸侵蚀有明显加剧的趋势;2016-2019年亚龙湾东部和西部海岸的岸滩下蚀速率分别约为-13.3 cm/a和-36.2 cm/a,西部岸滩下蚀速率远高于东部岸滩;亚龙湾全段为强侵蚀等级,其中东部岸段为强侵蚀等级,西部岸段为严重侵蚀等级;造成亚龙湾海岸侵蚀的原因主要包括海岸工程建设、植被破坏和海平面上升。 相似文献
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莱州湾东部潮上带土地利用对海岸蚀退的影响 总被引：1，自引：0，他引：1
基于二维浅水方程、波作用守恒方程和对流扩散方程, 建立了波浪-潮流-泥沙耦合数值模型, 分析了最近20 年来莱州湾东部潮上带土地利用对海岸蚀退的影响。结果显示, 潮上带土地利用改变 了风暴潮时的水动力边界条件, 显著增大了岸线附近的水流流速。随着潮上带养殖设施覆盖比例的 提高, 从平面分布看, 岸线附近侵蚀显著加重, 侵蚀条带平行岸线并向下游延伸、向海侧拓展; 从剖 面分布看, 岸线两侧侵蚀深度显著增大、范围明显扩展, 水下岸坡的闭合水深加大, 闭合点外移; 从 动力条件变化看, 岸线附近水流流速最大。分析表明, 最近20 年来大规模的潮上带土地利用是莱州 湾东部海岸蚀退的重要影响因素。 相似文献
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根据2014-2015年对大连李官华铜海岸、营口白沙湾海岸、营口仙人岛海岸以及营口鲅鱼圈月亮湾海岸的岸滩地形监测数据,依据海岸侵蚀灾害监测与评价技术方法,对辽东湾东岸的4个连续砂质海岸的稳定性进行了分析.结果表明:海滩岸线发生侵蚀的岸段主要分布在营口仙人岛海岸和大连李官华铜海岸南部,其中仙人岛岸段岸线后退距离最为严重,达到了7.8 m/a;从断面地形监测结果来看,大连李官华铜海岸发育较强侵蚀,岸滩下蚀速率为9.35 cm/a.辽东湾东岸的华铜海岸和仙人岛岸段,侵蚀现象仍然明显;而开展了防护修复工程的月亮湾、白沙湾等原侵蚀岸段,都基本趋于稳定,没有再发生海岸侵蚀现象. 相似文献
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通过波浪水槽实验,对海平面变化造成的波浪动力因素改变引起的沙质岸滩形态响应开展机理性研究。实验采用1∶10单一沙质斜坡概化岸滩,利用3种不同实验水深模拟海平面变化,考虑椭圆余弦波、非规则波、规则波和孤立波4种类型波浪作用。实验对波浪在斜坡上的传播变形、破碎、上爬和回落过程的波高及波浪作用后的岸滩地形进行了测量。实验结果表明,椭圆余弦波、规则波和非规则波作用下,平衡岸滩呈现出滩肩形态,孤立波作用下则呈沙坝形态。海平面上升造成波浪动力增强,沙质岸滩平衡剖面形状基本保持不变向岸平移,槽谷、滩肩、沙坝位置以及岸线蚀退距离,均呈现出良好规律性。 相似文献
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热带气旋前进方向两侧海滩风暴效应差异研究--以海滩对0307号台风"伊布都"的响应为例 总被引：11，自引：0，他引：11
在0307号台风“伊布都”(Imbudo)袭击华南沿海前后,对相距约300km的高栏岛飞沙湾(位于气旋前进方向右侧)和水东港下大海(位于气旋前进方向左侧)的固定海滩剖面地形及滩面沉积物进行了对比调查。调查结果表明,右侧海滩地形受台风暴浪冲击发生剧烈变化：后滨陆侧堆积,后滨向海侧及前滨滩面侵蚀(单宽侵蚀量达55m^3／m,平均海面(MSL)位置蚀退13m,岸线位置蚀退5m),以致剖面类型由滩肩式断面向沙坝式断面转变,表现出了海滩对台风做出快速响应;而左侧海滩剖面地形基本保持原状,虽也略呈侵蚀,但冲淤变化不大,表现为对台风做出迟缓响应。同时,从动力、滨海输沙、滩面沉积物变化和海岸地貌等方面对两侧海滩明显差异的风暴效应的机制进行了探讨。 相似文献
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Karim Nassar Wael Elham Mahmod Hassan Fath Ali Masria Kazuo Nadaoka Abdelazim Negm 《Marine Georesources & Geotechnology》2019,37(1):81-95
This study focuses on the shoreline change detection along the North Sinai coast in Egypt using geographic information system and digital shoreline analysis system (DSAS) during the elapsed period from 1989 to 2016. The measurement of shoreline variation is mainly described for three zones: zone I, El-Tinah plain bay; zone II, El-Bardawil Lake; zone III, El-Arish valley. The rates of shoreline changes in the form of erosion and accretion patterns are automatically quantified by four statistical parameters functioned in DSAS namely endpoint rate, net shoreline movement, linear regression rate (LRR), and least median of squares. LRR results elucidate that the western seaside of El-Tinah plain bay has experienced an extremely dynamic feature with an average erosion rate of ?8.17?m/year. The littoral drifts have been driven by eastward alongshore currents toward the east side of the bay to be accreted with an average rate of +4.28?m/year. Moreover, the shoreline has progressed west of El-Bardawil inlet (1), El-Bardawil inlet (2), and El-Arish harbor. Subsequently, the corresponding average beach growth rates are found to be +2.7, +8.5, and +6.5?m/year, respectively. In contrast, the shoreline on the down-drift side to the east has negatively retreated, and the corresponding beaches have regressed at rates of ?4.5, ?8.65, and ?2.9?m/year, respectively. 相似文献
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淤泥质海岸冲淤变化大，岸滩剖面形态多样。本文首先根据多时相遥感水边线之间的潮差关系自动判断岸滩剖面形态，进而分别采用不同的函数进行剖面拟合，构建了一种剖面形态自适应的海岸线遥感推算新方法，并在江苏中部淤泥质海岸进行了实证应用。研究表明:下凹形侵蚀岸段、斜坡形平缓岸段和上凸形淤长岸段分别采用三指数衰减函数、线性函数和二阶多项式函数具有良好的剖面拟合效果，利用3条水边线数据拟合所得剖面平均坡度绝对误差分别为0.20‰、–0.17‰和0.13‰，小于剖面实测平均坡度一个数量级。利用5条水边线数据拟合进行海岸线推算时，侵蚀岸段、平缓岸段的海岸线平面位置误差分别为6.5 m和–91.96 m，与平均坡度法相比，误差减小约82.4%。进一步考虑岸滩季节性变化时，使用冬季的水边线数据推算海岸线，对侵蚀岸段和淤长岸段影响不大，但对斜坡形平缓岸段，误差减小约63.65%，因此使用冬季的水边线数据比不区分季节具有更高的海岸线推算精度。 相似文献
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The abandoned Yellow River Delta coast is a typical erodible silty and muddy coast in China. The paper analyses the marine dynamic characteristics and the mechanism of beach erosion of this area. Analysis and calculation show that in this sea area wave and tidal current action should be considered. Based on the above analysis, an equilibrium beach profile calculation model is developed, in which the wave-current interaction is considered while sediment supply and sediment re-deposition are neglected. The model consists of four parts: (1) calculation of wave parameters, (2) calculation of velocity due to wave-current interaction at different water depth, (3) calculation of friction velocity and shear stress at different water depths, and (4) calculation of the amount of sediment erosion, erosion intensity and variation of beach profile. Calculated results are in good agreement with observed data. Finally, the evolution tendency is discussed and the equilibrium beach profile of this coast is calculated. B 相似文献
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基于遥感的广西防城湾海岸线变迁分析 总被引：1，自引：0，他引：1
随着人口增长、城市化和工业化的迅速发展、政策刺激以及对外贸易的日渐加强,防城湾沿岸海岸线变迁加剧。本文利用1973,1979,1990,2000年的Landsat卫星遥感影像和2010年的HJ-1B(环境与灾害监测预报小卫星星座B星)卫星遥感影像,分析了近40 a来防城湾海岸线的变化特征。结果表明:1973—2010年间,防城湾沿岸不断向海推进,陆域面积共增加了4 216.61 hm2;海岸线总长度则减少了36.96 km,其中淤泥质岸线减少最为剧烈,其次为基岩岸线;海岸线变化主要受人为因素影响。根据防城湾的区域特征,将整个研究区划分为防城江口、暗埠口江和渔澫岛3个岸段分别进行详细分析表明:防城江口沿岸以基岩岸线为主,海岸线在1973—2010年间变迁程度很小,仅在防城江河口沿岸向海扩张了约74.58 hm2;暗埠口江沿岸以淤泥岸线为主,近40 a间该岸段岸线不断向海推进,许多原本曲折多变的鹿角湾被逐渐填充;渔澫岛海岸线变迁最为剧烈,近40 a来陆域面积共增加了2 027.41 hm2,岸线长度缩短了2.46 km,遥感影像监测显示1990年时渔澫岛已经陆连,同时从渔澫岛的分形维数计算结果可以看出其海岸线日趋平直。 相似文献
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《Marine Geology》2007,236(1-2):45-59
Titanomagnetite forms rich placer deposits along the northwest coast of New Zealand. These deposits were sampled along 3 shore-normal transects spaced over the southern 2 km of a dissipative high-energy beach on the west coast in 5 field campaigns covering one year. The percentage of opaque minerals (mainly titanomagnetite) was extremely high in the upper 30 m of the beach face, extending seaward where these opaque minerals were gradually replaced with variable amounts of lighter augite, hornblende and plagioclase. The pattern appeared to be divided into two regions, a lower seaward and an upper landward region, separated by a point where either marine dominated over aeolian processes or where swash dominated over breaking processes. In the seaward region, the percentage of opaques increased and particle size fined landward as undertow removed the lighter larger particles seaward. In the landward region, the percentage of opaques and particle size were more constant, or even showed the reverse pattern as wind transported the lighter material shoreward, or swash asymmetry transported the heavier material seaward. The similarity of settling velocities over the whole beach face suggests that sorting by size rather than weight plays a dominant role in separating the mineral assemblages. Considerable variations existed between transects. This could be explained by the spatial changes in surfzone waves and currents that were associated with proximity to the southern headland and various rip current channels that characterised this dissipative site. Surprisingly, the percentage of opaques decreased when the wave conditions of the day of sampling were more energetic. In contrast to many other placer deposits, these deposits are abundant on the beach face, forming an armouring layer during lower wave energy conditions. During higher wave conditions, the surface layer erodes allowing lighter augite, plagioclase and hornblende to be released from the sediments below. 相似文献
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Torrey Pines State Beach, a site with large seasonal fluctuations in sand level, received a small shoreface beach fill (about 160,000 m3) in April 2001. The 600 m-long, flat-topped nourishment pad extended from a highway riprap revetment seaward about 60 m, terminating in a 2 m-tall vertical scarp. A 2.7 km alongshore span, centered on the nourishment region, was monitored prior to the nourishment and biweekly to monthly for the following 2 years. For the first 7 months after the nourishment, through fall 2001, significant wave heights were small, and the elevated beach fill remained in place, with little change near and above Mean Sea Level (MSL). In contrast, the shoreline accreted on nearby control beaches following a seasonal pattern common in southern California, reducing the elevation difference between the nourished and adjacent beaches. During the first winter storm (3 m significant wave height), the shoreline retreated rapidly over the entire 2.7 km survey reach, forming an alongshore-oriented sandbar in 3 to 4 m water depth [Seymour, R.J., Guza, R.T., O'Reilly, W., Elgar, S., 2004. Rapid erosion of a Southern California beach fill. Coastal Engineering 52 (2), 151–158.]. We show that the winter sandbar, most pronounced offshore of the nourishment, moved back onto the beach face during summer 2002 (following the usual seasonal pattern) and formed a wider beach above MSL at the site of the original nourishment than on the control beaches. Thus, the April 2001 shoreline nourishment was detectable until late fall 2002, persisting locally over a full seasonal cycle. In an extended 7-year time series, total sand volumes (summed between the back beach and 8 m water depth, over the entire 2.7 km reach) exhibit multi-year fluctuations of unknown origin that are twice as large as the nourishment volume. 相似文献
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ABSTRACTUnderstanding how and why the world’s coastlines are changing is a pressing international concern in a context of rising sea levels, increased climatic variability and intensifying coastal development. Medium to long-term records of coastal change are rare worldwide and often limited to individual beach compartments. This study presents a 70-year (1940–2010) aerial imagery record to compare decadal changes in shoreline position across four high-energy west coast beaches near Auckland, New Zealand/Aotearoa: Whatipu, Karekare, Piha and Te Henga (Bethells). The common exposure of these adjacent mesotidal beaches to changing wind and wave conditions might, if they present the dominant controls on shoreline position, be expected to produce synchronous change. Whatipu (935?m), Piha (32?m) and Te Henga (52?m) showed net overall progradation for the study period, while Karekare retreated slightly (?4.1?m). All except Whatipu underwent periods of beachwide erosion. Shoreline change was not coherent between beaches, despite similar exposure to variations in wind, wave and sea level. Variable sediment supply from northward littoral drift is implicated as the primary control on decadal-scale shoreline change for these beaches, highlighting the importance of local context in influencing shoreline response to changing environmental conditions. 相似文献