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1.
A. Aslan A. G. Warne W. A. White E. H. Guevara R. C. Smyth J. A. Raney J. C. Gibeaut 《Geomorphology》2001,41(4)
Mud volcanoes along the northwest margin of the Orinoco Delta are part of a regional belt of soft sediment deformation and diapirism that formed in response to rapid foredeep sedimentation and subsequent tectonic compression along the Caribbean–South American plate boundary. Field studies of five mud volcanoes show that such structures consist of a central mound covered by active and inactive vents. Inactive vents and mud flows are densely vegetated, whereas active vents are sparsely vegetated. Four out of the five mud volcanoes studied are currently active. Orinoco mud flows consist of mud and clayey silt matrix surrounding lithic clasts of varying composition. Preliminary analysis suggests that the mud volcano sediment is derived from underlying Miocene and Pliocene strata. Hydrocarbon seeps are associated with several of the active mud volcanoes.Orinoco mud volcanoes overlie the crest of a mud-diapir-cored anticline located along the axis of the Eastern Venezuelan Basin. Faulting along the flank of the Pedernales mud volcano suggests that fluidized sediment and hydrocarbons migrate to the surface along faults produced by tensional stresses along the crest of the anticline. Orinoco mud volcanoes highlight the proximity of this major delta to an active plate margin and the importance of tectonic influences on its development. Evaluation of the Orinoco Delta mud volcanoes and those elsewhere indicates that these features are important indicators of compressional tectonism along deformation fronts of plate margins. 相似文献
2.
.Introducti0nTheNandujianghiver,withalengthOf3llkIn,adrainageareaof684lkm2andanaverageannunldischargOf60xl09m',isthelargstriveronHainanIsland.IttransportsanaveragannualsedimentloadOfO.68xlO6tonsnorthwdintoQangrhouStrait,wherethetidalrangnisca1.Om,andwavesandlongrhorecurrentsarerelativelystrong.TheNandujiangdeltacoves20OkIn2.ThedePOsitionalSystemOfthedeltaconsistsofrivermouthbars,distribotarymouthbars,marshdepositsfOrmedinbaysandlagoons,sandridges,sandsPitsanddunes.ThedistributionPatt… 相似文献
3.
黄河三角洲造陆过程中的陆域水沙临界条件研究 总被引：26，自引：5，他引：26
黄河三角洲发育是河口区河流动力及陆域物质通量与海洋动力及海域物质通量相互作用的产物 ,三角洲造陆速率取决于上述两方面的对比关系。当上述两方面处于平衡时 ,三角洲造陆处于临界状态 ,即净造陆速率为零 ,与之相联系的入海泥沙量和径流量可视为黄河三角洲造陆过程的临界水沙条件。运用经验统计方法估算出 :当入海年沙量Qs为 2 78亿t/a、入海年水量Qw为 76 7亿m3时 ,或者当关系式 3 1934Qs+ 0 0 85 6Qw=17 94得到满足时 ,黄河三角洲造陆过程处于临界平衡状态。在黄河流域的环境管理中 ,应将上述两项临界值作为约束条件。黄河流域生态用水量的内涵应予以扩展 ,维持三角洲造陆平衡所必须的入海径流量 ,应作为黄河流域的生态用水量。 相似文献
4.
The construction of multiple dams and barrages in many Indian River basins over the last few decades significantly reduced river flow to the sea and affected the sediment regime. More reservoir construction is planned through the proposed National River Linking Project (NRLP), which will transfer massive amounts of water from the North to the South of India. The impacts of these developments on fertile and ecologically sensitive deltaic environments are poorly understood and quantified at present. In this paper an attempt is made to identify, locate and quantify coastal erosion and deposition processes in one of the major river basins in India—the Krishna—using a time series of Landsat images for 1977, 1990 and 2001 with a spatial resolution ranging from 57.0 m to 28.5 m. The dynamics of these processes are analyzed together with the time series of river flow, sediment discharge and sediment storage in the basin. Comparisons are made with similar processes identified and quantified earlier in the delta of a neighboring similarly large river basin—the Godavari. The results suggest that coastal erosion in the Krishna Delta progressed over the last 25 years at the average rate of 77.6 ha yr− 1, dominating the entire delta coastline and exceeding the deposition rate threefold. The retreat of the Krishna Delta may be explained primarily by the reduced river inflow to the delta (which is three times less at present than 50 years ago) and the associated reduction of sediment load. Both are invariably related to upstream reservoir storage development. 相似文献
5.
引滦工程对滦河三角洲的影响 总被引：28，自引：5，他引：28
本文根据滦河三角洲地区的野外调查及收集的大量资料，以引滦工程对滦河水文的影响为基础，全面系统地分析、论述了三角洲自然环境的变化：三角洲海岸侵蚀后退，地下水位下降，滦河口盐水入侵，土壤盐渍化，河床冲刷、拓宽，河口淤积，预测了三角洲环境演变的趋势，提出了控制三角洲变化的决策。 相似文献
6.
Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu 总被引：1，自引：0，他引：1
The delta evolution and erosion process of the abandoned Yellow River Delta (AYRD) have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model. In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance (D c) with the average range value (Ao) of grain size parameter. Filtering method (removing data that not at a sampling station) is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta (AS) is better than that in the northern part of the abandoned Yellow River Delta (AN). Sediment in the area is found to be anisotropy at the northeast-southeast direction. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between D c, Ao, sediment transport and delta evolution shows a close link between D c and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree. 相似文献
7.
Domains of spit evolution in the Goro area, Po Delta, Italy 总被引：2，自引：0，他引：2
Goro lagoon was formed during the 19th century in the southern part of the Po Delta. Its origin is related to the growth of a spit system, which progressively occluded the southernmost interdistributary bay from the sea. The development of the spits is due to the morphological prominence of the Po Delta which causes a divergent littoral drift, enhanced by wave refraction over the delta front. During the last century the spit was abandoned, destroyed, and re-constructed several times because of the development of newer spits seawards. Using historical maps and aerial photographs, three different periods are recognised, featuring distinctive spit growth styles: parallel, fan-shaped and branched. The different domains of spit evolution are related to several factors, mainly to the mutual influence of sediment discharge, sand mining along the Po river, wave action over the delta front, human-induced subsidence and direct human interventions along the spits and for flood-control. 相似文献
8.
The delta evolution and erosion process of the abandoned Yellow River Delta (AYRD) have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model. In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance (Dc) with the average range value (Ao) of grain size parameter. Filtering method (removing data that not at a sampling station) is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta (AS) is better than that in the northern part of the abandoned Yellow River Delta (AN). Sediment in the area is found to be anisotropy at the northeast-southeast direction. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between Dc, Ao, sediment transport and delta evolution shows a close link between Dc and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree. 相似文献
9.
珠江河口“门”的地貌动力学初探 总被引：11，自引：0，他引：11
珠江河口由河网区与河口湾区构成,连接两部分的是珠江口独特的地貌单元“门”。末次海进盛期古珠江海湾可分为内海湾和外海湾,现代三角洲平原与河网均发育在古内海湾。内、外古海湾通过峡口相连,这些峡口演变为现代的“门”。本文根据实测水文资料、地形图、钻孔资料,应用PRD-LTMM长周期动力-沉积-形态模型对珠江河口的“门”6000年来地貌动力学进行探讨：(1) 现代“门”双向射流动力系统,(2) “门”的演进阶段,(3)“门”对古潮汐能量的集聚作用,(4) 珠江河口各“门”与相应的三角洲平原的同步耦合演进, (5)“门”对珠江河网形成的作用。 相似文献
10.
In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×109 m3 and 3.41×108 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×1010 m3 and 2.42×108 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×108 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×108 t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea (SSCT) is 25.4–26.0 kg/m3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997. 相似文献
11.
珠江河口磨刀门的整治与地貌演变 总被引：2，自引：0，他引：2
从排洪通道、航运通道、排水通道的形成以及浅滩围垦等方面阐述磨刀门10 a综合整治的效 果.口门延伸、平原扩展及地貌类型、沉积构造及冲淤变化反映了近20多年来磨刀门从浅海 湾演变为三角洲的过程.“磨刀门外水下三角洲”未来的发展趋势受沉积基础、水动力条件 、泥沙运动和沉积作用的影响.由于水动力从径流优势型转变为径流-潮流优势型,沿岸流 、风暴潮、波浪的作用增强,使得口外海域的滩槽向西南方向延伸.未来“磨刀门外水下三角洲”治导线的布设应为南偏西,并保持大喇叭口态势. 相似文献
12.
通过提取1975年与2010年左右南海海岸带建设用地信息,并对南海海岸带区域进行地貌分区,分析了不同类型海岸带35年建设用地扩张空间格局.结果表明:① 华南大陆和马来半岛建设用地扩张普遍快,中南半岛扩张程度中等,苏门答腊岛,加里曼丹岛和菲律宾群岛除马尼拉湾外普遍扩张程度慢.② 不同海岸地貌因自然资源条件,开发难易程度,腹地大小不同,其建设用地扩张程度差异显著.三角洲平原岸和河口平原岸因水运条件好,腹地广,建设用地扩张普遍显著,台地岸和沙坝--潟湖平原岸因适宜建中小型港口,扩张较为显著,海湾平原岸与山地岸则因平原面积小,开发潜力有限,建设用地扩张普遍不大,平直沙堤平原岸因腹地小,水运不发达而扩张甚微.③ 不同类型海岸带开发模式各异.三角洲平原岸和河口平原岸建设用地空间形态多样化,山地岸,台地岸,海湾平原岸以团块状或条带状为主,沙坝--潟湖平原岸以团块状与星状为主,平直沙堤平原岸多呈条带状,线状或点状分布. 相似文献
13.
Modeling the growth limit of the Changjiang Delta 总被引：6，自引：0，他引：6
River deltas grow in response to sediment discharge from the land. It is not clear, however, whether or not there is a limit for such growth. Conceptual geometric models are used in this paper, in association with the principle of mass conservation, in an attempt to answer this question. Preliminary analyses of the Changjiang Delta indicate that delta growth is constrained by a number of factors: the original topography/bathymetry, sediment supply, sediment retention in the estuary, sea-level rise, ground subsidence. The quantity of sediment supply per unit area and the Sediment Retention Index for the subaqueous delta decrease as the delta progrades towards deeper water, resulting in a decreasing rate of growth. The limit of growth is reached when the index approaches zero, i.e. the shoreline reaches the shelf edge. If the combined effect of sea-level rise and ground subsidence is considered together with decrease in the sediment discharge from land, the limit is reached at an earlier stage. For the Changjiang Delta, the model output (using hypothesized Sediment Retention Index estimates) implies that the delta growth will reach its limit in the near future. This will occur sooner if the sediment output of the river is reduced to 60% of its original level, in response to the upstream basin changes. Further knowledge, however, is required of the Retention Index, together with the information on future changes in river input and the character of the sediments in order to improve the accuracy of the simulations. 相似文献
14.
华南与中南半岛三角洲发育特征之比较 总被引：1，自引：1，他引：0
韩江、珠江、红河、湄公河、湄南河三角洲同处东亚季风热带。河流丰水少沙,径流强劲, 洪枯流量比值大,洪泛平原和湿地发育,有珊瑚礁和红树林堆积,平原推进速率较大,出海口门多,这些都是热带三角洲的特色。各三角洲的构造基础都是断陷盆地,由于断陷的幅度和时代不相同,故而第四系的厚度和年龄差异很大。受全球海平面变化的影响,末次冰期以来,各三角洲经历了相似的沉积过程,发育3期三角洲。所处位置(湾内或湾外)、滨外陆架坡度、海洋动力等条件,使各三角洲的地貌类型、地面高程、平原推进速率、水下三角洲、水动力类型等有较大的差异。 相似文献
15.
The Yellow River is unique among the major rivers of the world because of its extremely heavy sediment load in relation to its small discharge. The Yellow River has changed courses numerous times during the past 5000 to 6000 years. With its large sediment load, most of which comes from the Loess Plateau of central China, the river has created a number of deltas along the coast of northern China. The abandoned deltas are eroding, whereas the present delta being formed in Bohai Bay is growing rapidly. Human activity, including extensive agriculture, heavy water consumption, the use of river-control structures, and war, has been responsible for many of the changes occurring in the Yellow River and its delta. [Key words: hydrology, loess, floods, Yellow River, Bohai Bay, China.] 相似文献
16.
J. F. Bijkerk J. ten Veen G. Postma D. Mikeš W. van Strien J. de Vries 《Basin Research》2014,26(3):351-368
Sequence‐stratigraphic models for fourth to sixth order, glacio‐eustatic sequences based only on relative sea‐level variations result in simplified and potentially false interpretations. Glacio‐eustatic sea‐level variations form only one aspect of cyclic climate variation; other aspects, such as variations in fluvial water discharge, vegetation cover, weathering and sediment supply can lead to variable sediment yield, thus adding complexity to sequence‐stratigraphic patterns normally attributed to sea‐level variations. Analogue flume models show a significant impact of water discharge on the timing and character of sequence boundaries, and on changes in the relative importance of systems tracts, as expressed in sediment volumes. Four deltas, generated under the influence of an identical sea‐level curve, and affected by different water‐discharge cycles were generated in the Eurotank facility: (1) constant discharge; (2) high‐frequency discharge variations (HFD); (3) discharge leading sea level by a quarter phase; (4) discharge lagging sea level by a quarter phase. HFD shift the parasequence stacking pattern consistently but do not alter large‐scale delta architecture. Water‐discharge changes that lead sea‐level changes result in high sediment yield during sea‐level rise and in the poor development of maximum flooding surfaces. Delta‐front erosion during sea‐level fall is expressed by multiple, small channels related to upstream avulsions, and does not result in an incised valley that efficiently routs sediment to the shelf edge. When water‐discharge changes lag sea‐level changes, sediment yield is high during falling sea level and results in rapid progradation during forced regression. Erosion from incised valleys is strong on the proximal delta top and dissipates towards the delta front. The combination of high discharge and sea‐level fall provides the most efficient mode of valley incision and sediment transport to the shelf edge. During sea‐level rise, low water discharge results in sediment starvation and well‐developed maximum flooding surfaces. Water‐discharge variations thus alter sequence‐stratigraphic patterns and provide an alternative explanation to the amplitude of sea‐level fall for generating either type 1 or 2 erosional unconformities. 相似文献
17.
近60年黄河水沙变化及其对三角洲沉积的影响 总被引：1，自引：1，他引：0
In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×109 m3 and 3.41×108 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×1010 m3 and 2.42×108 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×108 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×108 t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea (SSCT) is 25.4–26.0 kg/m3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997. 相似文献
18.
编制了珠江三角洲番禺台地东缘第四纪堆积阶地、陆域钻孔及海域地震探测等一系列联合剖面,分析了抬升区、下沉区和海陆之间的沉积差异和控制因素,剖析了地动型和水动型海平面变化对三角洲形成演化的影响,厘清了各组断裂的活动及其对三角洲沉积发育的影响,结果发现北东东向和北北西向2组断裂为珠江三角洲地区的主要活动断裂,它们共轭联动,控制着珠江三角洲沉积的格局和水道的变迁,尤其是北东东向断裂,可能是南海北部大陆架滨海断裂系的组成部分。相比而言,陆域断裂活动性较弱,以缓慢蠕动和断块的差异升降和掀斜为主,海域断裂活动性较强,滨海断裂带是危险性很高的活动大断裂。三角洲其他方向的断裂更新世以来无明显活动。 相似文献
19.
黄河口泥沙淤积估算问题和方法——以钓口河亚三角洲为例 总被引：11，自引：1，他引：10
以往在黄河三角洲沉积量的估算中,对沉积物干容重和计算边界等问题不够重视,导致计算结果存在明显出入。本项研究通过广泛收集资料和大量采样分析得到了多种沉积环境下沉积物干容重的计算模型,结合三角洲沉积结构分析和利用地形测量数据,计算了黄河口钓口河流路时期亚三角洲不同时期的沉积量。其中1965年至1974年间钓口河亚三角洲前缘坡脚以内的总淤积量为71.0亿t。其平均干容重为1.36g/cm3。这一干容重用于估算其它亚三角洲沉积量不会造成明显误差。认为忽略三角洲下松软沉积层的压实沉降、三角洲平原相和前缘相中粘性土与非粘性土干容重的差别以及来沙量的测量误差对计算结果影响较小。 相似文献
20.
渤海莱州湾南岸潍河-弥河三角洲:沉积序列和沉积格架 总被引：9，自引：2，他引：7
潍河-弥河三角洲是一个由多条河流共同塑造的三角洲。前三角洲黏土质粉砂是各河流共同贡献的结果;每条河口之外形成各自的三角洲前缘,主要由极细砂组成;河口间湾沉积物是两条相邻河流共同塑造的,主要为黏土质粉砂。由于河口位置的侧向摆动,三角洲前缘极细砂和河口间湾黏土质粉砂会交替出现。7000a B. P. 以来向海进积20~55km,在海岸附近三角州沉积物厚度超过20m。 相似文献