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1.
海岸生物地貌过程研究海岸带生物过程和动力-沉积-地貌过程之间的双向相互作用,是海岸生态系统响应和反馈全球变化的重要机制,被列为全球变化核心项目海岸带陆海相互作用研究的重点内容。20世纪90年代以来的调查研究揭示了华南红树林和珊瑚礁热带生物海岸生物地貌过程的主要特点。造礁石珊瑚的高生长率和珊瑚礁高堆积速率是珊瑚礁生物地貌过程的物质基础;红树林生态系统的高生产力、高归还率和捕沙促淤功能是红树林生物地貌过程的物质基础。热带生物海岸地貌结构显示分带性和生物地貌类型和动力地貌类型的叠加和共存,潮汐水位严格控制群落分布格局并形成重要的生物地貌界限。热带生物海岸生物地貌过程有利于消除或减缓海平面上升的浸淹效应。热带生物海岸不断加剧的人类活动干扰和生态破坏导致生物地貌功能削弱和海岸资源环境恶化。 相似文献
2.
河口海岸地处海陆交界带,其沉积层理特征与形成机制是沉积动力学、动力地貌学和地层学等学科方向的研究热点,对评价海岸工程环境效应、重建沉积古环境等具有重要参考价值。通过梳理河口海岸区域径流、潮汐、波浪等多种动力因子作用的研究成果,归纳不同动力主导作用形成的沉积层理特征,剖析3种基本动力对沉积层理塑造的动力学机制,阐释洪水、风暴偶发动力因子以及生物扰动、海平面变化、围垦工程等其他影响因子对沉积层理形成和保存的作用机理。同时,总结了数值模拟手段在沉积层理形成和破坏机制解译方面的应用及取得的机理认知,提出在河口海岸沉积层理时空尺度认知、多因素耦合反演模型开发应用等方面有待进一步研究的科学问题。 相似文献
3.
海岸带是陆地、海洋和大气相互作用最强烈的地带,也是受全球气候、海平面变化以及人类活动影响最大的地区。海岸带动力过程具有明显的海洋-陆架-海湾-海岸多尺度多物理场特点,动力地貌过程和响应机制极具特色。台风等极端气象事件的频繁发生,工程措施等强人类活动的影响,导致海岸带动力地貌演变规律呈现出更大的不确定性。从高强度扰动下海岸动力条件、极端条件影响下海岸动力地貌特征和强人类活动影响下海岸动力地貌特征等方面,综述了已有研究工作进展。全球气候变化和人类活动共同作用的海岸带多尺度动力过程和海岸地貌响应内在机制极其复杂,在未来海岸动力地貌特征的研究中,需要进一步从大气、海浪、海洋和泥沙等多物理场,海洋、陆架、海湾和海岸等多尺度,动力条件、泥沙输移和地貌塑造等多过程的角度,探究高强度扰动下海岸带动力过程、响应机制和演变规律。 相似文献
4.
盐沼潮滩作为滨海湿地的一个重要类型,为河口海岸地区提供了多种关键的生态服务功能,具有重要的社会、经济与生态价值,其地貌演变规律的认知是海岸带保护修复和科学管理的基础。回顾国内外近一个世纪以来针对潮滩动力地貌过程的研究工作,发现研究热点已逐渐从传统的研究潮滩水-沙-地貌相互作用过渡到探索植物、动物、微生物等生物作用与动力、地貌之间的互馈机制,涉及海岸动力学、地貌学、沉积学、环境生态学等多个学科,是典型的交叉学科前沿研究领域。归纳了盐沼植被与潮滩多种因子的相互作用,总结了常用的盐沼潮滩地貌演变模拟手段及取得的机理认知,并提出今后在生物作用、陆海耦合动力地貌模型研发等方面的科学问题和发展方向。 相似文献
5.
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
6.
《上海国土资源》2010,31(3):1-8
2010年9月16日上午,本刊主编、上海市地质调查研究院总工程师严学新教授与本刊编辑部主任、上海市地质调查研究院总工程师办公室副主任龚士良教授,在华东师范大学河口海岸国家重点实验室恽才兴教授的陪同下,专程拜访了我国河口海岸学科的先驱、中国工程院院士、华东师范大学河口海岸研究院名誉院长陈吉余教授,在陈院士90华诞前夕对他进行了专访。陈院士针对上海后备土地资源、滩涂合理开发利用、生态湿地保护与置换、海岸带地质工作拓展、海平面上升与城市安全、人工岛及港岛建设、人类第三驱动力的作用效应等诸多社会广泛关注的热点问题发表了独到见解和精辟论述,强调指出：上海城市发展与资源利用必须坚持＂发展、合理、公平、协调＂八字方针,并对本刊提出殷切希望。 相似文献
7.
滩涂围垦对盐沼湿地碳收支的影响研究进展 总被引：1，自引：0，他引：1
《地球科学进展》2017,(6)
滨海盐沼湿地是全球重要的碳库,也是典型的脆弱生态系统。近年来,随着人口的增加,滨海盐沼湿地围垦开发已经成为缓解区域人口压力,保障粮食安全,促进经济发展的一项重要措施,特别是在发展中国家。围垦活动过程中必然会改变原有生态系统碳循环的路径和模式,进而影响全球的碳收支平衡。通过对大量文献的检索与总结,对国内外3种滨海盐沼湿地类型(红树林盐沼湿地、河口潮滩盐沼湿地和海岸潮滩盐沼湿地)土壤有机碳含量、固碳速率、碳排放速率以及围垦后的变化进行梳理和概括,给出滨海盐沼湿地围垦后土壤碳循环的一般规律与变化趋势,结果表明:(1)欧美长期滩涂开发形成的认识与滩涂围垦后的生态环境效应演变不适用于东亚发展中国家的短期高强度农业围垦,应注重东亚地区海岸围垦方式下的碳效应研究;(2)从滩涂湿地有机碳含量及其固碳速率来看,红树林盐沼湿地最高,河口潮滩盐沼湿地次之,海岸潮滩盐沼湿地最低。土壤黏粒、团聚体和埋藏速率对其具有较为明显的正向效应;淹水频率、盐分、地下水位反之。滩涂围垦后土壤有机碳含量呈先降后增的趋势,其转折点在围垦后30年左右,水田耕作对滩涂土壤有机碳富集效果最明显;(3)滩涂盐沼湿地的主要碳排放方式是CH_4和CO_2,其中CO_2的排放强度和通量都较大,且以红树林盐沼湿地最高。芦苇和互花米草的土壤碳排放强度相比于光滩要大很多。涨潮的过程中湿地碳排放强度要明显低于涨潮前后。滩涂围垦后的土壤碳排放强度要明显高于自然滩涂土壤,特别是围垦后的旱田耕作下的CO_2排放。从监测的结果来看,围垦前滩涂湿地表现为较强的碳汇,而围垦后表现出较为明显的碳源。最后,提出今后研究的重点方向和内容:抓紧开展滨海盐沼湿地碳收支清单的制定;不同围垦方式对滨海盐沼湿地碳循环影响的定量表达;加强开展未来滨海围垦模式及其土壤碳循环响应的刻画与模拟研究。 相似文献
8.
现代地貌学的发展与思考 总被引：2，自引：0，他引：2
简要回顾了地貌学的发展史 ,认为现代地貌学的发展必须与时代发展趋势相结合 ,需要深入研究地貌演变与全球气候环境变化、区域经济可持续发展以及地球陆地系统的关系。综合分析了地貌学的研究方法 ,认为地貌学的研究方法主要有沉积学方法及动力过程方法。传统地貌学的研究多偏重于沉积学的方法。过去是认识现在的一把钥匙 ,沉积学方法是研究地貌发展历史与过程的有力工具 ,但要深入认识地貌演变的过去与现代动力过程与机制 ,进而预测地貌过程的演变趋势 ,必须采用动力过程分析的方法。动力地貌研究的发展应该汲取过程反映学派及数学地貌学派的经验教训 ,避免过于重视工具 ,本末倒置 ,甚至演变为数学游戏或模型游戏。动力地貌学的研究将彻底改变过去人们眼中对传统地貌学的印象———仅仅是现象描述和宏观分析。动力地貌学通过引进动力学模型、数学模型及地理信息系统等研究方法和技术 ,采用宏观与微观相结合 ,全面深入探讨各种地貌产生、发展的机制和规律。它具有动态性和较强的预测功能 ,从而可以更好地为经济建设和社会实践服务。文中还探讨了地貌学的各个发展方向 ,认为环境地貌、灾害地貌、城市地貌、旅游地貌、河口海岸地貌等应用地貌学分支近年来发展迅猛 ,主要是因为这些分支与经济发展的需求结? 相似文献
9.
海南岛南渡江河口动力沉积模式 总被引：1，自引：0，他引：1
河口是一个迅速变化的、动态的海岸巨系统。作为陆地河流和和海洋过程的重要链接,河口的动力沉积过程一直是陆海相互作用研究的核心和焦点内容。本文基于2011年8月在南渡江河口采集的大范围表层沉积物样品,利用经验正交函数分析技术（EOF）对河口的动力沉积特征进行研究。结果表明:南渡江河口海床表层沉积物主要以砂为主,沉积物总体偏粗;河口的动力沉积特征自陆向海可分为三种动力沉积模式:①波控模式,该模式主要分布在河口地区10 m以浅的近岸区域,呈与岸线平行的带状分布,其表层沉积物以粉砂质砂为主,分选较差;②径、潮流耦合作用下的沉积模式,在径流和潮流的共同控制作用下,沉积物主要表现为粒径较粗,该模式呈扇形分布,其中20 m以浅河口海床受控于径流和潮流的共同作用,20 m以深海床表现为潮流控制的沉积模式;③台风或风暴潮控制的沉积模式,即整个河口海床都表现出受控于台风或者风暴潮作用的沉积特征,沉积物主要是以粗砂为主。常态作用下,河口以径、潮流控制的沉积模式为主,波浪、径流和潮流以及潮流控制的沉积模式自陆向海的规律性分布体现出南渡江河口近岸以波浪作用为主,而离岸则受河口尤其是洪水作用形成的喷射流以及沿岸潮流的影响。此外,尽管南渡江河口在过去的成果中将其归纳为波控河口,但目前的研究发现:该河口区域沉积类型变化明显受控于不同的动力作用,河口形态以及琼州海峡的障蔽和“狭管效应”为河口沉积环境变化的主要控制因素。 相似文献
10.
红树林是湿地生态系统的重要组成部分,是生长在热带、亚热带河川、海岸滩涂潮间带的乔灌木群落,是由陆地向海洋过渡的特殊生态系统,红树林素有“海上森林”、“海底森林”、“海岸卫士”、“海水淡化器”等美称.作为海岸湿地生态系统惟一的木本植物,它具有防风搏浪、护岸护堤、调节气候等功能,对抵御海潮、风浪等自然灾害,维护和改善海湾、河口地区的生态环境具有不可替代的作用. 相似文献
11.
Estuarine tidal mudflats form unique habitats and maintain valuable ecosystems. Historic measurements of a mudflat in San Fancsico Bay over the past 150 years suggest the development of a rather stable mudflat profile. This raises questions on its origin and governing processes as well as on the mudflats’ fate under scenarios of sea level rise and decreasing sediment supply. We developed a 1D morphodynamic profile model (Delft3D) that is able to reproduce the 2011 measured mudflat profile. The main, schematised, forcings of the model are a constant tidal cycle and constant wave action. The model shows that wave action suspends sediment that is transported landward during flood. A depositional front moves landward until landward bed levels are high enough to carry an equal amount of sediment back during ebb. This implies that, similar to observations, the critical shear stress for erosion is regularly exceeded during the tidal cycle and that modelled equilibrium conditions include high suspended sediment concentrations at the mudflat. Shear stresses are highest during low water, while shear stresses are lower than critical (and highest at the landward end) along the mudflat during high water. Scenarios of sea level rise and decreasing sediment supply drown the mudflat. In addition, the mudflat becomes more prone to channel incision because landward accumulation is hampered. This research suggests that sea level rise is a serious threat to the presence of many estuarine intertidal mudflats, adjacent salt marshes and their associated ecological values. 相似文献
12.
中国淤泥质潮滩沉积研究的进展 总被引：19，自引：1，他引：19
中国淤泥质潮滩积研究由早期的野外地貌，沉积的定性描述到详细的动力地貌过程的半定量定量研究，时间尺度已由长期至一周、一天。“波浪掀沙、潮流输沙”的物理过程的征兵听数学模拟研究淤泥质潮滩侵蚀、堆积的机制提供了一个很好的途径。 相似文献
13.
潮滩盐沼物理过程的研究进展综述 总被引：9，自引：2，他引：9
综述了本世纪国外潮滩盐沼堆积、侵蚀机制的研究进展，主要包括潮滩盐沼的粘性泥沙沉积动力机制的分析、对潮滩盐沼的物理过程的详细观测研究、沉积模式研究，以及潮滩盐沼物理过程的知识在海岸防护和其它方面的应用。 相似文献
14.
《Sedimentology》2018,65(5):1631-1666
Detailed logging and analysis of the facies architecture of the upper Tithonian to middle Berriasian Aguilar del Alfambra Formation (Galve sub‐basin, north‐east Spain) have made it possible to characterize a wide variety of clastic, mixed clastic–carbonate and carbonate facies, which were deposited in coastal mudflats to shallow subtidal areas of an open‐coast tidal flat. The sedimentary model proposed improves what is known about mixed coastal systems, both concerning facies and sedimentary processes. This sedimentary system was located in an embayed, non‐protected area of a wide C‐shaped coast that was seasonally dominated by wave storms. Clastic and mixed clastic–carbonate muds accumulated in poorly drained to well‐drained, marine‐influenced coastal mudflat areas, with local fluvial sandstones (tide‐influenced fluvial channels and sheet‐flood deposits) and conglomerate tsunami deposits. Carbonate‐dominated tidal flat areas were the loci of deposition of fenestral‐laminated carbonate muds and grainy (peloidal) sediments with hummocky cross‐stratification. Laterally, the tidal flat was clastic‐dominated and characterized by heterolithic sediments with hummocky cross‐stratification and local tidal sandy bars. Peloidal and heterolithic sediments with hummocky cross‐stratification are the key facies for interpreting the wave (storm) dominance in the tidal flat. Subsidence and high rates of sedimentation controlled the rapid burial of the storm features and thus preserved them from reworking by fair‐weather waves and tides. 相似文献
15.
Omran E. Frihy 《Environmental Geology》2009,58(6):1177-1189
Although the western-Mediterranean coast of Egypt between Sallum and Alexandria, ~550 km long, has maintained a considerable
equilibrium throughout history, developers have built traditional protective structures in an effort to form sheltered recreational
beaches without taking into consideration its geomorphologic characteristics, coastal processes and their harmful impact on
the coastal environment and human safety. The improper practices in this environmentally valuable region have induced us to
undertake an initiative to carry out a morphodynamic analysis to provide a framework for understanding the relationship between
coastal morphology and the prevailing dynamic forces. Based on the degree of natural protection or wave sheltering, the study
shoreline can be categorized into four distinct morphotypical stretches: (1) high-energy wave-exposed shores and the outer
margins of the rocky headlands, (2) moderate to high wave-energy beaches along semi-exposed embayments and bays mostly downdrift
of the rocky headlands, (3) low-wave energy at semi-exposed headland lee-sided and pocket beaches, and (4) calm wave-sheltered
enclosing water basins for safe anchorages, moorings and recreation beaches. The results deducted will have practical applications
for shoreline management initiatives regarding sustained sites suitable for future beachfront development such as safe swimming
conditions, sport facilities, water intakes and sheltered areas for vessels. In addition, benefits realized by the understanding
of the morphodynamic processes would enhance our awareness of the significance of the role of western coast morphodynamics
in supporting sustainable development via shoreline management. As far as sustainability is concerned, the selection of appropriate
sites would help avoiding or minimizing the formation of the hard structures needed for creating safe recreation beaches.
On a national scale, results reached could provide reliable database for information that can be used in establishing a sustainable
shoreline management plan, which is, in turn, an essential part when implementing an Integrated Coastal Zone Management Plan
for this region of attraction. 相似文献
16.
Mudflats and associated mangroves are most important ecosystems of tropical coastal regions. Mangroves play a very important role in maintaining the environmental balance; thus in addition to mangrove reforestation and restoration, afforestation has also been practiced. We studied distribution of sediment components (sand, silt, clay) organic carbon (OC), heavy metals (Fe, Mn, Cu, Zn, Cr and Co) and pH in six cores collected from one of the largest mudflats of Mandovi estuary, west coast of India. The temporal distribution patterns of these proxies suggested that past changes in tidal energy conditions, fresh water inflow and anthropogenic activities over the last few decades, together helped in development of a middle tidal flat in this estuary. In cores collected from the mangroves, trapping and deposition of finer particles and organic matter were enhanced by a complex aerial mangrove root system in recent years. Mangroves were, therefore, suggested to enhance the buildup of mudflats in Mandovi estuary. Cores collected from mudflats also exhibited higher deposition of finer particles and organic matter (except MF2) in recent years, suggesting maturity and greater stability of the entire mudflat in recent years. Middle tidal flats (mudflats) of Mandovi estuary may, therefore, prove to be suitable substrates for mangrove proliferation in the near future. Finer sediments deposited mainly from mining activities in recent years exhibited lower pH and higher metal content. Organisms dwelling in these recently deposited sediments are, therefore, at higher risk of bioaccumulation and metal toxicity. 相似文献
17.
Sedimentary successions of non‐marine basins can be considered in terms of accommodation space and sedimentary supply changes. Changes in accommodation space controlling the large‐scale architecture of non‐marine basins are different in areas with high and low sedimentary supplies. Uplift of intrabasinal monoclines and anticlines reduced the available accommodation space, resulting in changes in both the geometry of the depositional sequences and the large‐scale architecture of fluvial, mudflat and shallow carbonate lacustrine deposits. Main drainage fluvial systems record areas with a high sedimentary supply, while mudflats and shallow fluctuating lakes represent areas that received less sediment. Two end members in the large‐scale architecture of main drainage fluvial system in the Almazán Basin (Spain) are: (i) ribbon‐shaped channel fills with low interconnectivity which pass laterally into mudflats dominated by mudstones and evaporites and into palustrine and shallow carbonate lacustrine deposits (mainly in the A2 depositional sequence); and (ii) sheet‐like channel fills with high interconnectivity laterally correlated with stacked calcretes in the marginal mudflats (in the upper part of A3). Ribbon‐shaped channel fills formed in areas of high accommodation space and sheet‐like channel fills formed in areas of reduced accommodation space. 相似文献
18.
Following heavy winter storms and sedimentation in 1993,Spartina foliosa (Pacific cordgrass) clones established on a 6.5-ha mudflat in Tijuana Estuary, with over 80 new clones counted by 1997. El Niño Southern Oscillation (ENSO) storms in 1993 apparently facilitated the habitat conversion through river flooding, which caused a temporary reduction in soil salinity and delivered large volumes of sediment. Extreme sedimentation likely raised mudflat elevations enough to allowSpartina establishment. We hypothesized that clones, once established, increased sedimentation in a positive feedback loop leading to accelerated habitat conversion. We collected data on elevation,Spartina expansion, and sediment accretion in two consecutive years (1998–1999). The elevation range of the mudflats in 1998 (0.5–0.83 m NGVD) was within the elevation range ofSpartina at this site (0.39–0.83 m NGVD), indicating that remaining mudflats are at elevations suitable for further expansion. Sediment accretion ranged from 4.0–12.7 cm between 1997–1998 (ENSO conditions), but was close to long-term averages (? cm yr?1) in 1998–1999 (nonflood year) indicating how susceptible Tijuana Estuary is to sedimentation from episodic storms. Although accretion rates were similar withinSpartina clones and on bare mudflats over the ENSO winter, clones were typically dome-shaped suggesting higher sediment retention rates within clones. The radial expansion rates of clones (1.31±0.25 m in 1998; 1.12±0.07 m in 1999) approximated the maxima reported for this species and were not related to clone size or vigor. Conditions on the mudflat appear ideal forSpartina growth, masking differences that might otherwise be observed. Given the likelihood of sedimentation-driven habitat conversion in southern California and other Mediterranean-type estuaries, management efforts are needed to address sedimentation issues on a watershed scale. We recommend that wetland restoration projects in southern California include large areas of intertidal mudflat, both to maintain habitat for shorebird feeding and to allow colonization by salt marsh vegetation. 相似文献
19.
为探究江苏中部沿海双凸型剖面演变特性,在江苏盐城川东港南侧潮间带布设了10个水准观测站,2012年9月至2013年11月对该潮滩剖面演变过程开展了现场观测.结果表明:该潮滩剖面呈现出双凸型特征,平均高、低潮位线附近的滩涂形成淤积率较高的地形凸点;潮间上带受潮流影响小,滩面高程相对稳定;平均高、低潮位之间的区域滩面高程季节性变化明显,总体呈现冲刷状态;潮间下带冲刷显著,滩面坡度增大.全剖面自岸向海呈现"稳定—淤积—稳定—淤积—冲刷"的双凸型剖面特征. 相似文献
20.
Measurements over an annual cycle of longitudinal and vertical salinity distributions in a small sub-estuary, the Tavy Estuary,
UK, are used to illustrate the dependence of salt intrusion and stratification on environmental variables. The interpretations
are aided by vertical profiling and near-bed data recorded in the main channel and on the mudflats. Generally, high water
(HW) salt intrusion at the bed is close to the tidal limit and is dominated by runoff and winds, with decreasing salt intrusion
associated with increasing runoff and increasing up-estuary winds (or vice versa). Tidal effects are not statistically significant
because of two compensating processes: the long tidal excursion, which is comparable with the sub-estuary length for all but
the smallest neap tides, and the enhanced, near-bed, buoyancy-driven salt transport that occurs at small neap tides close
to the limit of saline intrusion. The effect of wind on HW surface salt intrusion in the main channel is not statistically
significant, partly because it is obscured by the opposing local and estuary-wide effects of an up-estuary or down-estuary
wind stress. These processes are investigated using a simple tidal model that incorporates lateral, channel–mudflat bathymetry
and reproduces, approximately, observed channel and mudflat velocities. Surface salinity at HW increases with tidal range
because of enhanced spring-tide vertical mixing—a process that also reduces salinity stratification. Stratification increases
with runoff because of increased buoyancy inputs and decreases with up-estuary winds because of reduced near-bed salt intrusion.
Stratification and plume formation are interpreted in terms of the bulk and estuarine Richardson Numbers, and processes at
the confluence of the sub-estuary and main estuary are described. 相似文献