互花米草盐沼潮沟地貌特征

互花米草是我国从国外引进的能在淤泥质潮滩的高潮带下部和中潮带上部生长的禾木科植物,由于其植株高大、群落盖度高、根系发达等生物学特性,其对潮流动力特征有显著的影响。本文通过对江苏省东台市笆斗垦区外互花米草盐沼地的潮沟形态调查,发现互花米草盐沼潮沟具有以下一些特征:潮沟密度大,可达50km/km²以上;潮沟的宽深比小,大多在8以下;沿岸堤发育,且多呈不对称状;一级主潮沟与主潮沟接头处普遍呈逆弧形;盐沼外侧边缘发育有明显的陡坎冲沟。分析认为这些特征主要与互花米草发达的根系和致密的植株等生物学特性有关,发达的根系增加了盐沼滩面的稳定性,而互花米草高大的植株增加了对潮水运动的阻力,提高了滩面落潮水的归槽水位,改变了潮流的泥沙沉积地点和涨、落潮流的流向,从而形成比较特别的互花米草盐沼潮沟特征。     

江苏王港盐沼的现代沉积速率

江苏海岸湿地总面积超过5000km^2，但围垦活动的加剧使盐沼湿地面积迅速减少；为了达到海岸防护、保滩促淤的目的，先后引种了大米草和互花米草。通过采集江苏王港潮滩盐沼湿地9处柱状样和挖取探槽剖面，以及对沉积剖面样品进行^210Pb和^137Cs测年分析，探讨了^210Pb的本底及影响^210Pb富集的因素，估算了王港盐沼湿地的现代沉积速率。王港潮滩盐沼沉积物对^210Pb的吸附作用较弱；受风暴潮、生物扰动、物源变化及实验误差等因素的影响，在^210Pbex剖面上出现了数据异常点，将这些数据点剔除后计算得到的沉积速率为33cm yr^-1，^137Cs测年显示，该地区1963年以来的平均沉积速率3．1cm yr^-1，与^210Pb法及前人研究结果相一致。根据一个典型剖面的^137Cs测年数据分析，王港潮滩盐沼的沉积过程根据地貌特征的不同可分3个阶段，大米草覆盖阶段滩面高程迅速增加，互花米草的生长提高了滩面淤积速率。     

模拟流域地貌发育过程的空间数据获取与分析

运用数字摄影测量与GIS技术对人工模拟降雨条件下小流域模型地貌发育过程进行了动态监测研究,获得了小流域模型不同发育阶段地貌形态高精度、高分辨率的DEM数据、等高线、纵横剖面等数据,计算出了流域模型各种地貌形态参数,并利用GIS技术进行流域发育过程的空间形态进行了可视化和空间分析.研究表明,数字摄影测量与GIS技术可准确快速获取流域地貌形态的相关参数及小流域土壤侵蚀的空间定量分布,对于黄土高原小流域降雨侵蚀产沙过程与地貌形态特征定量作用关系研究及小流域土壤侵蚀预报模型建立具有重要科学意义.     

大河口潮滩地貌动力过程的研究-- 以长江口为例

该文阐述河口潮滩的发育依赖于河流泥沙来源、河口动力和海底地形诸方面的有利条件.长江口潮滩在世界大河三角洲潮滩发育中独具特色.大河口潮滩的平面形态有“长条状”、“裙状”、“沙咀状”和“江心洲”型,横剖面形态有“宽缓型”、“陡岸型”和“侵蚀崖型”.主河道两侧潮滩水流基本上是往复流,但岛屿面向外海一侧的潮滩是旋转流.潮滩近底流速随着高程的增大而减小.虽然潮汐始终是潮滩水动力的控制因子,但径流起着加强落潮流和改变流速不对称性的作用.潮滩上的波能随风力、水深、滩坡和植被状况而变化.长江口潮滩水体属高浑浊水体,悬沙浓度变化于每升几百毫克至每升几万毫克之间.在总体迅速淤涨的背景下,大河口潮滩存在不同时间尺度的冲淤循环.     

新月形沙丘迎风坡气流加速模拟

迎风坡气流加速是决定新月形沙丘发育和形态的动力因子，研究这一加速过程的定量关系有利于认识沙丘的发育、沙丘的形态、沙丘的运动等。通过大量的野外实测数据和前人的理论分析，得出沙丘迎风坡气流加速量主要和沙丘坡度、迎风坡前来流风速以及沙丘高度有关，并建立了新月形沙丘迎风坡气流加速和沙丘形态特征的定量关系。根据这一关系得了在风力较强的风沙环境中，沙丘坡度较小；在风力较弱的风沙环境中，沙丘坡度较陡。地表粗糙度越大，迎风坡坡度越陡。沙丘地貌发育高度存在一上限，这一上限与边界层厚度有关。     

大河口潮滩地貌动力过程的研究—以长江口为例

该文阐述河口潮滩的发育依赖于河流泥沙来源，河口动力和海底地形诸方面的有利条件。长江口潮滩在世界大河三角洲潮滩发育中独具特色，大河口潮滩的平面形态有“长条状”，“裙状”，“沙明状”和“江心洲”型，横剖面形态有“宽缓型”，“陡岩型”和“侵蚀岩型”。主河道两侧潮滩水流基本上是往复流，但岛屿面向外海一侧的潮滩是旋转流，潮滩近底流速随着高程的增大而减小，虽然潮汐始终是潮滩水动力的控制因子，但径流起着加强落潮流和改变流速不对称性的作用，潮滩上的波能随风力，水深，滩坡和植被状况而变化，长江口潮滩水体属高浑浊水体，悬沙浓度变化于每升几百毫克至每升几万毫克之间，在总体迅速淤涨的背景下，大河口潮滩存在不同时间尺度的冲淤循环。     

江苏省淤泥质海岸潮沟系统

江苏省淤泥质潮滩是最适于潮沟系统发育的潮滩之一。本文分析了影响潮沟系统发育的诸因素,进行了潮沟系统形态与潮差的相关分析,并把江苏的潮沟系统与沪、浙、闽等省市的潮沟系统进行了对比。主要结论如下:1.影响潮沟发育的主要因素是在落潮后期才存在的沟渠效应;2.潮沟和潮盆是潮滩上规模较大的韵律地形;3.粉沙级沉积物最宜于发育潮沟;4.潮沟的某些形态特征与潮差有非常好的线性相关;5.陆地迳流干扰了潮沟发育过程。     

长江口盐沼土壤有机质更新特征的滩面趋势

通过对长江口崇明东滩高潮滩、中潮滩以及光滩柱状样的有机元素(C、N)含量与碳稳定同位素组成(δ13C)、粒度组成等的测定,研究盐沼土壤有机质更新特征及其滩面趋势.结果表明,长江口盐沼土壤POC-δ13C相关特征与山地土壤剖面上部土层的基本类似,盐沼土壤有机质主要源于长江流域表层土壤,有机质年龄不足100年.不同高程柱样TN-C/N、POC-TIC与POC-δ13C关系特征表明盐沼土壤有机质更新程度普遍较低,有机质更新特征呈明显的滩面变化趋势.光滩有机质基本反映沉积母质特征,更新程度极低;中、高潮滩有机质更新作用已经发生,随着滩面演变,处于不同更新阶段的有机质组分混杂程度提高.盐沼滩面过程塑造垂向沉积层序,层序中独特的沙、泥纹层构造导致物质上下运移困难,有机质更新作用受到抑制.盐沼滩面过程直接影响有机质的累积与更新,对于有机质更新的时空特征具有显著制约.     

呼伦贝尔沙质草原风蚀坑形态发育模式分析

 野外调查测量呼伦贝尔沙质草原风蚀坑分布和形态参数,根据不同发展阶段的风蚀坑形态特征的差异、形态参数间相关关系和拟合结果分析了风蚀坑的形态演变和发育、成因、规律。发现不同发展阶段风蚀坑形态参数之间的控制关系和扩展模式不同,各形态参数之间具有较好的幂函数关系。对于风蚀坑的侵蚀坑而言,坑长增长速度最快,其后依次是坑宽和坑深,坑后积沙体具有类似规律。风蚀坑坑后积沙的3个形态参数,受侵蚀坑3个参数的联合控制,但受坑深的控制最为显著。风蚀坑出现的起始形态、地形特征、植被、气流场、气候条件、人类活动的扰动等对其形态和发育具有重要影响,并且形态和发育反作用于植被、气流等,形成形态与气流、植被之间的响应与反馈。     

植物残体干扰对黄河河口高潮滩盐沼芦苇生长的促进作用

为研究植物残体干扰对黄河河口高潮滩盐沼芦苇生长的影响,在黄河河口高潮滩盐沼中分别选择典型的植物残体干扰斑块和未受干扰的自然群落,调查了其中芦苇（Phragmites australis）的形态特征及其种群的密度和生物量,并取样测定了土壤盐度、含水量、容重等土壤物理、化学性质,运用方差分析方法研究了植物残体干扰对芦苇的形态特征及其种群的密度和生物量的影响以及对土壤性质的影响。结果表明,植物残体干扰斑块中芦苇种群的密度、生物量等明显高于未受干扰的自然群落,芦苇的形态特征也明显优于未受干扰的自然群落。这说明植物残体干扰对芦苇生长产生了明显的促进作用。在植物残体干扰斑块中,土壤盐度、容重显著低于自然群落,说明植物残体干扰对黄河河口高潮滩盐沼芦苇的生长起到的促进作用,可能是通过改善土壤环境,缓解物理胁迫而产生的。     

Salt-marsh foraminifera in Ho Bugt,western Denmark,and their use as sea-level indicators

Twenty-seven surface samples were collected from the Kjelst Enge salt marsh in Ho Bugt, Jutland, to investigate the potential use of salt-marsh foraminifera as sea-level indicators in Holocene intertidal deposits. Previous work from many coastlines around the world has shown that the vertical distribution of salt-marsh foraminifera is strongly controlled by the duration of tidal flooding (or height relative to tide level). Concentrations of foraminifera in Kjelst Enge salt marsh are low, especially in the high marsh, but a strong correlation was found between relative abundances of foraminiferal species and tidal elevation for 16 samples containing more than 30 specimens per 5 cc of sediment (r² = 0.80, root mean square error = 0.16 m). Sediment pH also has a strong influence on the distribution of the foraminifera, but salinity appears to be insignificant.     

江苏中部海岸互花米草扩展对滩涂围垦的响应

根据2001-2013年遥感影像和野外观测数据,对江苏中部海岸互花米草(Spartina alterniflora Loisel)在滩涂围垦期间的扩展过程进行定量化分析。结果显示：2001-2013年互花米草扩展对围垦的响应大体分为三个阶段：2001-2007年,海堤外米草面积较大,每年新增米草面积及米草年扩展率均和新增围垦面积变化同步,且相关性显著;2008-2010年,海堤外米草面积较小,但米草年扩展率仍然较高;2011-2013年,随着围垦的持续进行,米草扩展进入稳定期。因此,互花米草扩展对于滩涂围垦的不同速率和阶段具有不同的响应。若围垦时保留足够宽度的堤前米草,则围垦可以提高米草的年扩展率,其机理是互花米草种子产量和前缘淤积环境是影响米草扩展的主要因素,而围垦对这两方面都有影响。在后期滩涂围垦时,应保证堤外米草宽度在0.9~1 km之间,实现土地资源的可持续利用。     

An empirical–conceptual gully evolution model for channelled sea cliffs

Incised coastal channels are a specific form of incised channel that are found in locations where stream channels flowing to cliffed coasts have the excess energy required to cut down through the cliff to reach the outlet water body. The southern coast of the Isle of Wight, southern England, comprises soft cliffs that vary in height between 15 and 100 m and which are retreating at rates ≤ 1.5 m a^− 1, due to a combination of wave erosion and landslides. In several locations, river channels have cut through the cliffs to create deeply (≤ 45 m) incised gullies, known locally as ‘Chines’. The Chines are unusual in that their formation is associated with dynamic shoreline encroachment during a period of rising sea-level, whereas existing models of incised channel evolution emphasise the significance of base level lowering. This paper develops a conceptual model of Chine evolution by applying space for time substitution methods using empirical data gathered from Chine channel surveys and remotely sensed data. The model identifies a sequence of evolutionary stages, which are classified based on a suite of morphometric indices and associated processes. The extent to which individual Chines are in a state of growth or decay is estimated by determining the relative rates of shoreline retreat and knickpoint recession, the former via analysis of historical aerial images and the latter through the use of a stream power erosion model.     

Generalised observations of wave characteristics on near‐horizontal shore platforms: Synthesis of six case studies from the North Island,New Zealand

Most field studies of wave processes on shore platforms in front of eroding cliffs focus on a single site, revealing aspects of wave dynamics at that location. Here, we analyse data from six platforms around northeastern New Zealand and describe the fundamental control of shore platform width, gradient and elevation on wave processes, including greater attenuation of short‐period waves at lower tidal stages and increases in longer period wave energy towards the cliff toe. These data suggest that empirical formulae developed from coral‐reef environments provide better predictions of wave height on platforms than formulae currently used in shore platform models.     

Sandstone terrain in a semi‐arid littoral environment: the Lower Murchison Valley,Western Australia

Stream and wave erosion have cut spectacular cliffs in the Tumblagooda Sandstone in the Murchison gorge and along the adjacent coast. The sandplain above the cliffs developed between the Late Cretaceous and the Mid Tertiary but whether it formed at low level and was then uplifted or was formed at its present elevation is not known. The upper 30 km of the gorge post‐dates the laterite on the sandplain. As there is little runoff from the sandplain, erosion is limited to the edge of the gorge. Joints have controlled erosion of small tributaries but have had very limited effect on the course of the Murchison proper. Facies changes within the sandstone are reflected in the form of the cliffs. Very extensive cavernous weathering on the cliffs is attributed to crystallisation of salt. Comparisons with sandstone terrains elsewhere suggest that lithology may be just as important as climate in controlling large‐scale spatial variation of landforms.     

Patterns in the sand: From forcing templates to self-organization

The nearshore region exhibits many striking morphological patterns with a variety of spatial and temporal scales. The formation of these rhythmic features has been initially ascribed, depending on the pattern in question, to spatial structures in the flow or geological constrains. These forcing templates have been hypothesized to provide the spatial structure that becomes imprinted on the shoreline or seabed morphology. More recently, new explanations for rhythmic patterns have involved interactions between fluid flow and sediment transport that create morphological feedbacks and lead to pattern self-organization. While forcing-template models do not explicitly treat transport of the sediment that makes up the pattern, self-organization models focus on the strong couplings within flow/sediment systems, and on interactions between emergent structures. We illustrate the sweeping shift from template explanations to self-organization by discussing four nearshore patterns: beach cusps, surfzone crescentic sandbars, inner-shelf sorted bedforms, and large-scale cuspate shorelines. Models involving self-organization show that local interactions between flow and sediment transport can collectively give rise to patterns with large-scale coherence and that the driving feedbacks can be associated with either topographical or grain-size composition instabilities. An approach based on self-organization also allows researchers to establish limitations in the predictability of the occurrence of rhythmic patterns and characteristics as well as to study mechanisms leading to the observed variability of pattern or lack of regularity.     

The development of talus slopes around Lord Howe island and implications for the history of island planation

Lord Howe Island is a small eroded remnant of a Late Miocene shield volcano. A fringing coral reef dissipates wave energy along a portion of the shoreline, but the remainder of the coast is rugged with spectacular high basaltic sea cliffs. This paper investigates the evolution of talus slopes that occur beneath the loftiest cliffs, and places this analysis within the context of a longer history of island planation that has resulted in a wide truncated shelf around the island. During the Last Glacial, when the sea level was lower than at present, talus slopes accumulated around the extent of the island's cliffed coast because material eroded from cliffs by subaerial processes could not be removed by marine processes. The survival of these slopes during the Holocene has depended on a balance achieved between rates of subaerial and marine erosion. This balance is fundamentally influenced by cliff height, as cliffs higher than 200 m are plunging or veneered by talus slopes, whereas lower cliffs have erosional shore platforms. On comparison with published erosion rates from inland basalt scarps it appears that marine processes may account for over 90 per cent of the total cliff retreat that has occurred at Lord Howe Island, yet contemporary coastal morphology attests to the significance of subaerial processes in recent times. It is likely that marine cliffing was very rapid soon after volcanism ceased, but rates of erosion decreased through time as wave energy became increasingly attenuated across a widening planation surface, and as increasing cliff heights yielded greater quantities of talus that provided protection from rapid marine erosion.     

潮间带短期冲淤过程的横向差异及其定量表达——以长江口南汇滨海岸段的观测分析为例

根据1999年4月～2000年4月对长江口滨海某研究断面上24个观测点的定期(每周一次)滩面高程测量结果的分析,定量化地探讨了滩面垂直淤积速率和稳定性的横向差异。结果表明:(1)滩面的年垂直淤积速率在淹没机率为30%左右的沼泽中下部(位于平均小潮高潮线与平均高潮线之间)达到49.5cm/a的最大值。自这点向岸和向海垂直淤积速率逐渐降低,向岸在近堤处(接近平均大潮高潮位)达到最小值2.2cm/a(仅为最大值的1/22),向海在光滩—沼泽交界处出现另一低值,而在光滩上又有所增大。(2)由于植被的抗冲护滩功能,沼泽带滩面的相对稳定性远大于光滩带。分析认为:上述滩面冲淤过程的差异是潮水淹没机率、波浪和潮流能量以及植被分布上横向差异的综合体现。     

盐城潮滩湿地对N、P营养物质的截留效应研究

研究了盐城潮滩芦苇（Phragmites australis）、盐蒿（Artemisia schrenkiana）、互花米草（Spartina alterniflora）和淤泥光滩4种湿地对N、P营养物质的截留效应.在所选取的4种湿地中,分别采集了水、土壤和生物样;水样的总氮（TN）、总磷（TP）用过硫酸氧化还原法测定,土壤和生物样的TN、TP分别用凯氏定N法和钼锑抗比色法测定.研究结果显示,不同污染程度的水源灌溉下的芦苇湿地,其截留N、P的效果差异显著.其中,黄沙港不定期污水灌溉的芦苇湿地每年平均可截留TN 0.095 t/hm^2、TP 0.026 t/hm^2;而采取三灌三排方式用河水灌溉的新洋港芦苇湿地每年可分别截留TN 0.030 t/hm^2、TP 0.001 t/hm^2.比较盐蒿、互花米草和淤泥光滩3种湿地每年对湿地水中N、P的截留效果,淤泥光滩的效果最差,仅截留TN 0.385 kg/hm^2、TP 0.042 kg/hm^2;互花米草效果最好,分别截留TN 220.660 kg/hm^2、TP 36.754 kg/hm^2.尽管互花米草生物量大于芦苇,但其截留效果仍低于芦苇湿地（芦苇1 a收割1次）.