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海岸线变迁环境地质问题研究--以福建南部沿海地区为例 总被引：2，自引：0，他引：2
林军 《地质灾害与环境保护》2006,17(1):29-34
海岸侵蚀、淤积是改造沿海地质环境的主要因素之一。利用遥感技术和时空对比分析等监测手段来揭示地质环境的这种深刻变化,以及对人类生存环境所产生的客观影响,是未来环境地质研究的热点和难点问题。在系统总结现代海岸地质地貌特点及全新世以来海岸变迁概况的基础上,对福建南部沿海地区海岸线变迁的现状与发展趋势进行探讨。在当前世界海平面上升的总体情况下,海岸侵蚀将成为全球性海岸带最主要的自然灾害;海湾淤积影响港口城市的可持续发展;滩涂淤涨给水产养殖业带来了新的问题。 相似文献
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以实地调研资料为依据,对苏中黄海岸带的侵蚀、淤积作出系统分析。将苏中岸段分为北侵蚀、南淤积两大段,射阳河口以北的面大套河口为侵、淤转换中介点。作者从地貌形态、地层岩性(结构构造为主)、入海河口与风浪组合的水动力条件着眼,对侵、淤形成机制作了简要分析,并对发展趋势作出了概略预测,最后针对岸带侵、淤特点,提出岸带保护措施及滩涂资源开发利用方向。本文可供海岸滩涂资源开发利用规划及地质灾害防治参考利用。 相似文献
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作为环渤海海岸带近现代地质环境变化、人类与海岸带相互影响 (特别是现代社会、经济活动的巨大作用 )的研究程度最高的岸段之一 ,渤海湾泥质海岸带在近年来进行了以浅表地层记录的近现代地质环境变化为主要目的的 1 :5 0 0 0 0地质调查。在渤海湾西岸从北至上高公路 (上古林 (白沙岭 )、南至马棚口以北 1 5 0km2 内 (白水头幅 ,J5 0E0 0 80 1 5 )的 5 0个全取芯浅孔 ,揭露了 6～ 8m以内、距今数千年来的浅表地层。它们被分为 1 1层 ,分属“黄色单元”(盐沼、泻湖等 )和“灰色单元”(以开放潮间带为主 ) ;所有钻孔的孔口高程均经全站仪水准… 相似文献
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海岸带地区近百年来的现代地质过程重建必须以精确的年代学研究为基础,~(137)Cs时标法和~(210)Pb_(exc)测年法是目前广泛应用的方法。由于易受到河流沉积物供给变化、潮位状况、极端天气事件等的影响,海岸带现代过程的定量研究一直是高分辨率研究的瓶颈。区域性参考剖面可以提升现代沉积物测年方法在海岸带应用中的可靠性。因此,建立区域性的~(210)Pb_(exc)和~(137)Cs比活度-深度参考剖面,将改善对海岸带及邻近海区实测数据的解释。以渤海湾海岸带为研究区,选取沉积环境相对稳定、水平搬运作用较小的地区,采用人工探坑、Eijkelkamp槽型取样器获取了2个柱状岩心,通过γ能谱仪对样品进行~(210)Pb、~(226)Ra及~(137)Cs比活度测试,绘制剖面图,结合研究区已有数据,总结出6类海岸带常见的~(210)Pb_(exc)和~(137)Cs比活度-深度剖面类型,并重建了渤海湾海岸带~(137)Cs区域性参考剖面。结果显示,~(137)Cs在渤海湾地区的最大峰值指示1963年,可以作为区域性主要参考时标。但是,最大峰值上部的次峰在不同区域指示不同的时标,S4和S5两个站位该峰值指示的并非1986年时标。 相似文献
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淤泥质海岸带地区10～102a级别的相对快速的“缓变型地质环境变化”,主要包括水体、湿地和盐沼-湖退化或消失、贝壳堤和牡蛎礁被破坏、村镇和城市面积剧增、海岸线(平均大潮高潮线)被侵蚀后退、潮间带和近海河道被淤积、潮间带变宽变缓等。这些变化,已对我国东部沿海地区的经济和社会发展造成不利影响,并将对该类地区的可持续发展构成潜在威胁。在该类地区正在进行的1∶50000区域地质调查,充分发挥其高精度和规范化的优势,并辅以对近百年来不同时期的地形图、航空照片和遥感影像的数字化处理和对比研究,试图对这些变化做出形象、直观和定量的二维(2D)表达。本文介绍的是正在渤海湾海岸带进行的工作,充分显示出地质调查服务社会的公益性、基础性和战略性特点。对这一研究方向所显示的巨大潜力的进一步开发,将可能形成供政府决策部门和各方面用户广泛利用的、可二次开发的平台,从而使该类地区的可持续发展建立在对近现代地质环境变化详细了解的扎实基础之上。 相似文献
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Neelima Thankappan Noujas Varangalil Thomas Kachapally Varghese Kurian Njaliplackil Philipose 《Natural Hazards》2018,90(3):1177-1199
Shoreline changes are largely dependent on coastal morphology. South-west coast of India is a high energy coast characterised by monsoon high waves, steep beach face and medium-sized beach sand. Waves are generally from west and west south-west during rough monsoon season and from south-west during fair weather season. Shoreline change along this coast is studied with reference to coastal morphological features. Various morphological features, modifications and chronological positions of shoreline are analysed with the information derived from multidated satellite imageries, toposheets and GPS shoreline mapping along with extended field survey. Image processing and GIS techniques have been used for the analysis of data and presentation of results. Sediment accumulation on the leeward side of artificial structures such as harbour breakwaters and groynes is used as a sediment transport indicator. Artificial structures such as seawalls, groynes and harbour breakwaters modify morphology. Shoreline south of headlands/promontories and breakwaters are stable or accreting due to net northerly longshore sediment transport while erosion tendency is observed on the north side. Lateritic cliffs fronting the sea or with seasonal beach undergo slumping and cliff edge retreat as episodic events. Spits adjoining tidal inlets are prone to shoreline variations due to oscillations of inlet mouth. Interventions in the form of inlet stabilization and construction of coastal protection structures trigger erosion along adjoining coasts. Seawalls constructed along highly eroding coasts get damaged, whereas those constructed along monsoon berm crest with frontal beaches for protection against monsoon wave attack are retained. Fishing gaps within seawalls are areas of severe temporary erosion during rough monsoon season. Accretion or erosion accompanies construction of harbour breakwaters in a stable coastal plain. Close dependence of shoreline changes on morphology necessitates detailed understanding of impacts on morphology prior to introducing any intervention in the coastal zone. 相似文献
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泉州湾处于我国东南沿海构造活动带,具有发生地震的地质环境和同震海岸崩塌、海湾下沉的构造地貌条件。通过对泉州湾海滩岩产状、14 C测年、古生物化石及岩石学特征的研究分析,认为其物源为海岸崩塌的志留纪花岗岩和潮滩、河口堆积的陆源碎屑。搬运方向自南向北偏东,形成于泉州湾北部潮间带接近高潮位,在温暖和高蒸发的气候条件下有淡水参与,由钙质胶结发生的快速成岩作用。海滩岩形成的地质时代为全新世晚期,是突发性海洋强动力事件的记录,可能与距今2 000a在泉州湾以南发生的古地震造成深沪湾岩岸大规模崩塌和海湾快速下沉引发的海啸有关。 相似文献
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锦州湾泥沙主要来源于沿岸入海河流的输送,外海水体的携带与沿岸、岛屿蚀余物质的补给。每年进入湾内的泥沙总量约为３３—３５万吨,假如这些泥沙不再向湾外流出,在湾内作均匀分配沉积,则相当于在湾底铺上５ｍｍ厚的土。水准和水深重复测量表明,潮滩以稳定的弱堆积为主,水下浅滩基本处于稳定状态。该湾在非正常情况下产生骤淤的可能性不大。综合建港条件良好。 相似文献
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基于ROMS海洋模式,结合近年的地质实测资料,建立了渤海湾西部地区风暴潮漫滩的数值模型。对模型进行验证后,对渤海湾西部区域重现期为50a、100a、200a及500a的风暴潮漫滩进行了数值模拟,分析了不同重现期风暴潮漫滩发展的动态过程及最大漫滩淹水范围。结果表明,数值模型基本能反映风暴潮的增水趋势,能够模拟风暴潮漫滩发生发展的动态过程。随着风暴潮强度的增加,渤海湾西部地区淹水范围具有从东海岸向西部内陆区域扩展的趋势。通过曲线拟合发现,风暴潮最大漫滩面积比值与高水位之间基本呈线性关系。 相似文献
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Coastal salt marshes represent an important coastal wetland system. In order to protect coastlines from erosion and rapid
increase in accumulation rate, Spartina alterniflora (S. alterniflora) was introduced into the Chinese coast. Two study areas (Wanggang and Quanzhou Bay) were selected that represent the plain
type and embayment type of the coastal salt marshes. In situ measurements show that the tidal current velocities are stronger
on the intertidal mudflat without S. alterniflora than that with S. alterniflora, and the velocity above the canopy surface is larger than that in the salt marsh canopy. The existence of S. alterniflora also influences the velocity structure above the bare flat during ebb tide. With the decrease in current flow velocity when
seawater enters into the S. alterniflora marsh, suspended sediments are largely entrapped on the marsh surface, leading to increase in sedimentation rates and change
in physical evolution processes of the coastal salt marshes. The highly developed root systemof S. alterniflora induces sediment mixing and exchange between subsurface sediment strata and affects the vertical sediment distribution remarkably.
The sedimentation rate of S. alterniflora marsh at the Wanggang area is much higher than the relative sea level rise rate, where rapid progradation of theWanggang
saltmarshes that is protecting the coast from sea erosion is observed. 相似文献
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Tampa Bay, a large, microtidal, clastic-filled estuary incised into Tertiary carbonate strata, is the largest estuary on Florida’s west coast. A total of 250 surface sediment samples and 17 cores were collected in Tampa Bay in order to determine the patterns and controlling factors governing the recent infilling and modern sediment distribution, and to examine the results in terms of current models of estuarine sedimentation and development. Surficial sediments in Tampa Bay consist of three facies types, each occurring in a distinct zone: modern terrigenous clastic muds occurring in the upper bay and around the bay periphery; relict, reworked-fluvial, quartz-rich sands occupying the open portion of the middle bay; and modern carbonate-rich, marine-derived sands and gravels occupying the lower bay. Factors controlling sediment distribution include: sediment source and supply rate; bathymetry, which is a function of the antecedent topography; and the winnowing effect of wind-generated waves that prohibits modern accumulation in the shallow middle bay. These factors also play a major role in the recent infilling history of Tampa Bay, which has progressed in four stages during the Holocene sea-level rise. Recently developed models of estuarine sedimentation are based primarily on mesotidal to macrotidal estuaries in terrigenous clastic settings in which sedimentation patterns and infilling history are a result of the relative contribution of marine and fluvial processes. Tampa Bay differs in that it was originally incised into carbonate strata, and neither fluvial or marine processes are interpreted to be major contributors to modern sediment distribution. Tampa Bay, therefore, provides an example of an unusual estuary type, which should be considered in future modeling efforts. *** DIRECT SUPPORT *** A01BY083 00004 相似文献
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渤海湾沿岸贝壳堤对潮滩有孔虫海面变化指示意义的影响 总被引：1，自引：1，他引：0
通过对渤海湾沿岸有贝壳堤发育和无贝壳堤发育的2类现代开放潮滩有孔虫组合的对比,研究了该2类潮滩环境沉积物中有孔虫的海面指示意义。5个有孔虫组合带被MHWST(平均大潮高潮位)、MHW(平均高潮位)、MHWNT(平均大潮低潮位)和MSL(平均海面)分隔,分别对应潮滩的高盐沼、低盐沼、潮间带上部、潮间带中上部和潮间带中下部5个不同亚环境。不同亚环境沉积物因其所含的有孔虫群的独特性,均可作为高精度海面标志物,误差为各亚带高差的1/2。沿岸贝壳堤可对潮滩有孔虫的属种组成产生影响,影响程度从高潮位向低潮位逐渐降低。在MHWNT潮位之下,有孔虫组合不再受到沿岸贝壳堤的影响。 相似文献
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渤海湾西北岸大吴庄牡蛎礁是近年来研究程度最高的礁体,天津空港物流中心牡蛎礁则是近年来新发现的礁体。该两处礁体上部的牡蛎个体内部充填的泥、个体之间的泥以及礁体上覆沉积泥层中的硅藻研究表明,礁顶上下（即礁体的上部-顶部和上覆沉积泥层的下部）均富含潮间带环境指示种的Auliscus caelatus,表明礁体发育后期和上覆沉积泥层的初期,均为潮间带环境。尽管如此,从礁顶向上覆沉积泥层转换方式在两处礁体却不相同:（1）大吴庄:Auliscus caelatus种向上逐渐减少,暗示着大吴庄剖面由礁体上部的潮间带中上部、直至上覆沉积泥层下部的潮间带上部、进一步向上覆沉积泥层上部的潮上带转化的趋势。（2）空港:牡蛎礁上覆沉积泥层出现了比例达6%~23%的河口咸水-半咸水种Achnanches brevipes,而下伏礁体内则未见该种,暗示此处泥层受河口作用显著影响。此种不同揭示了礁体停止发育的原因有所不同:在5 520cal BP时,大吴庄礁顶进入潮间带中上部,礁体经常脱离海水而发育停止;在约4 000 cal BP时,空港礁体所在位置因河流作用突然增强,在时间上看很可能是黄河改道在天津入海,古黄河携带大量泥砂入海,掩盖了潮间带的牡蛎礁而导致牡蛎礁发育停止。 相似文献