广西防城港海域沉积物特征及输运趋势

通过对2010―2011年在广西防城港海域表层沉积物所取样品进行粒度实验,并利用二维沉积物粒径趋势分析模型进行了粒径输运趋势分析。结果表明,研究区海域底质沉积物类型主要为砂、粉砂质砂、砾石质砂、砂-粉砂-黏土、黏土质粉砂和砂质粉砂等6种。粒度参数在空间分布上,沿岸和西部海域中值粒径较粗,分选中等或较好,偏态呈正偏或极正偏,在海湾口处呈负偏或极负偏;东南部海域粒径较细,分选系数差,偏态呈负偏或近对称。根据沉积物输运趋势方向不同,将研究海域分为3个区：沿岸海域主要离岸输送,方向由北向南;东南部海域的沉积物输运趋势向中间汇聚,形成一个沉积中心;西南部海域,沉积物输运方向偏北。     

北部湾东北部沉积物运移趋势分析

选取北部湾东北部约450个表层样品进行粒度分析,并采用矩法计算各粒度参数(平均粒径、分选系数、偏态),利用Gao-Collins粒径趋势分析模型模拟出海底表层沉积物净输运趋势,发现北部湾东部底质沉积物运移规律:总体上是由陆地向海洋输送,靠近雷州半岛一侧主要为由南向北输送,输运过程中部分沉积,部分转向东南沉积,在该调查区域大体存在8个较为明显的沉积汇聚区;同时对约230个站位利用LISST激光粒度仪进行悬浮体粒级现场测量,选取各站位底层体积总浓度作图分析,发现该海区底层悬浮体体积总浓度快速变化区与底质泥沙汇聚区具有一定的对应关系,为在该海区研究沉积物运移趋势提供了一条新的途径。     

中国东部沙区表层沉积物粒度特征

通过分析中国东部沙区表层沉积物粒度特征及其与风力、植被覆盖的相关性,探讨了东部沙区现代风沙沉积环境及其区域差异性。结果显示:东部沙区各沙漠/沙地粒径级配相对一致,均以细沙、中沙为主,粒度分布整体呈单峰形态,中等分选,粒度分布和分选性均与西部沙区有较大不同。风力和植被覆盖状况的差异决定了各沙地所处的风沙环境性质和风沙活动强度不同,导致东部沙区表层沉积物粒度特征存在明显的区域差异性。其中,库布齐沙漠粒度特征与该区风蚀、搬运、堆积过程频繁交替的风沙活动方式密切关联;呼伦贝尔沙地粒度特征反映了风蚀主导的风沙环境;科尔沁沙地、浑善达克沙地,毛乌素沙地粒度特征和风沙活动方式相对复杂,与这3个沙地内部风蚀主导区和沙尘沉降主导区镶嵌分布的格局有关。东部沙区表层沉积物平均粒径和分选系数均与沙地年均风速和植被总盖度双因素之间具有显著的非线性相关性。     

流域环境变化的河流沉积物粒度响应——澜沧江案例

河流沉积物对流域环境变化具有敏感响应,其粒度参数能反映水动力环境。本文以澜沧江为研究案例,探究河流沉积物粒度对流域环境变化的响应。从澜沧江干流19个主要控制断面采集河床沉积物样品,用筛分法和吸管法对沉积物样品粒度参数进行测定,并分析了粒度参数的时空变化规律及其对流域水能开发为主的人为环境变化的响应。研究结论认为:1在空间尺度上,上游高原区,河谷宽坦,下蚀微弱,水流平缓,沉积物粒度较小,分选较好,呈负偏或近对称小峰度分布;中游高山峡谷河段,水流湍急,沉积物粒径变粗,分选相对上游较差,但整体分选良好,粒度出现较多正偏尖峰分布;下游中低山宽谷区受到梯级大坝的影响,河床沉积物中值粒径和平均粒径明显增大,且平均粒径增大更明显,分选变差,偏态趋向正偏,峰态尖锐化。2不同时间的样品粒度变化,反映梯级大坝致使坝下游沉积物中值粒径和平均粒径明显增大,且中值粒径增大更明显,分选变差,偏态趋向正偏,峰态尖锐化。研究结果既符合河流上下游沉积物粒度分布规律,也反映了河流环境变化对沉积物粒度组成的影响。     

毛乌素沙地南缘横向沙丘粒度分布及其对风向变化的响应

在风季发生转换期间, 根据不同方向风的持续时间, 对毛乌素沙地南缘长48m, 高8m 的 横向沙丘进行了7 次断面形态测量和表面沉积物采样分析。结果表明, 横向沙丘断面形态及表面 沉积物粒度分布随区域气流方向和强度而发生变化。在沙丘各部位, 丘顶及附近两侧的沙粒活动 性强, 表面沉积物粒径及分选参数变化显著。在粒径及分选参数中, 粒径频率曲线、平均粒径和偏 度对风的作用比较敏感, 随时间的变化也明显, 利用它们的变化可以解释区域气流变化对沙丘的 影响。风向发生转换时期的短期观测和采样分析结果进一步说明采样时间是影响沙丘表面沉积 物粒度特征的重要因素。     

西藏定结地区爬坡沙丘粒度特征分析

通过对西藏定结地区典型爬坡沙丘表层沉积物的形态参数、粒度组成和粒度参数等进行分析，揭示其粒度特征。结果表明：（1）爬坡沙丘表层沉积物以细砂和中砂为主，极细砂含量较少，同时含有少量粉砂和粗砂，不含粘土成分。（2）沙丘平均粒径范围1.98~2.41 Ф，分选系数变化范围为0.45~0.75，属中等分选，偏度变化范围为0.01~0.12，呈近对称至正偏分布，峰度变化范围为0.94~1.01，呈中等尖锐峰态。（3）从样品PPSQ1~PPSQ6，随着高度和距离的增加，沙丘表层沉积物平均粒径先变细后变粗，分选不断变好。（4）爬坡沙丘表层沉积物主要来源于河漫滩。（5）与雅鲁藏布江、东昆仑山地区爬坡沙丘对比可知，定结地区的沙丘粒径较粗，分选较好，主要是物源及风力分选作用的共同结果。     

末次冰期旋回风成沉积物图解法与矩值法粒度参数的对比

运用GRADISTAT粒度处理软件,分别计算了末次冰期黄土高原西部等地的黄土古土壤和风成砂的粒度参数,并对图解法与矩值法粒度参数进行了对比。结果表明,对黄土古土壤来说两种方法所获得的平均粒径基本相同,分选系数、偏度和偏态的相关性逐渐降低。对风成砂和砂黄土来说,除了平均粒径呈较好的线性相关外,其它参数则差别很大。造成这种差异的主要原因是它们的粒度组分的分布不同。黄土古土壤的粒度分布尽管呈双峰分布,但次峰通常较小,故尾部部分对粒度参数影响不大;而风成砂和砂黄土的次峰的频数较大,对粒度参数的影响很大。图解法主要反映了主要粒度组分的粒度特征,而矩值法则反映了样品的总体特征。在沉积环境的分析和比较时,应充分考虑这两种方法的差异,建立不同的等级标准。     

西藏朋曲流域不同地貌部位流动沙丘粒度特征

沙丘粒度特征不仅能反映沙丘沙物质的来源与动力,也可以体现地形对风沙流运移的改变。对西藏朋曲流域不同地貌部位流动沙丘表层沉积物的粒度特征进行分析。结果表明：（1）朋曲流域流动沙丘表层沉积物粒度组分以中沙（46.51%）和细沙（40.52%）为主,粗沙（5.87%）与极细沙（5.87%）次之,黏土（0.37%）与粉沙（0.85%）含量最低。流动沙丘表层沉积物平均粒径1.41—2.32 Φ,分选系数0.45—0.79 Φ,偏度0.01—0.24,峰度0.98—1.80。（2）从河漫滩到河流阶地到山坡,流动沙丘粒度逐渐变小,频率分布曲线逐渐变高变窄,粒径越来越集中,沿主导风向自西南向东北概率累积曲线斜率逐渐增大,分选性逐渐变好。（3）河漫滩至河流高级阶地流动沙丘表层沉积物随海拔升高粒径变小,坡麓至坡顶随海拔升高粒径变大,分选却变好,表明山坡上沙丘与阶地上沙丘的沙物质来自于不同河段的河床或河漫滩。     

毛布拉格孔兑地表风沙沉积物粒度与地球化学元素分布特征

通过对毛布拉格孔兑流域的地表积物的粒度、化学元素的空间分布的分析,得出的结论:毛布拉格孔兑河流附近沙物质组成表现为风成特性;不同河段沉积物平均粒度参数、化学元素的分布具有一定相似性,且元素之间存在高度的相关性,表明其具有相似的沉积环境;不同河段A-CN-K图解揭示了毛布拉格孔兑不同河段地表物质化学风化程度均很低,处于较弱的去Na、Ca阶段;不同地貌单元沉积物粒度组成、地球化学过程表现出一定的递变规律,可能物源有关;毛布拉格孔兑平均粒径与元素的含量存在较好的相关性,说明粒径大小与化学风化程度有一定关系;总之,在不同空间尺度上,毛布拉格孔兑地表沉积物理化特征的分异实质上反映风动力和水动力的差异性分选,即沉积物对风、水交互作用的响应。这对于构建风水两相沉积物综合判别指标等问题有着重要的意义。     

杭州湾南岸互花米草生物海岸表层沉积物粒度分析

互花米草盐沼可显著改变潮滩的水动力条件、沉积特征和地貌演化过程。分析杭州湾南岸互花米草滩内外表层沉积物的粒度特征,互花米草生物海岸沉积物包括粘土质粉砂、粉砂、粉砂质砂和砂质粉砂4类,由东向西各断面草滩内、外沉积物中值粒径逐渐变粗,分选性变好;从低潮滩向高潮滩沉积物的中值粒径Φ值增大,分选性变差。互花米草滩外边界处形成沉积物中值粒径及分选系数的突变点。杭州湾南岸生物海岸表层沉积物以跃移质为主,悬移质次之,推移质最少;由海向岸悬移质、跃移质和推移质均有变细趋势。     

The application of geostatistics in grain size trend analysis: A case study of eastern Beibu Gulf

There are 71 surface sediment samples collected from the eastern Beibu Gulf. The moment parameters (i.e. mean size, sorting and skewness) were obtained after applying grain size analysis. The geostatistical analysis was then applied to study the spatial autocorrelation for these parameters; while range, a parameter in the semivariogram that meters the scale of spatial autocorrelation, was estimated. The results indicated that the range for sorting coefficient was physically meaningful. The trend vectors calculated from grain size trend analysis model were consistent with the annual ocean circulation patterns and sediment transport rates according to previous studies. Therefore the range derived from the semivariogram of mean size can be used as the characteristic distance in the grain size trend analysis, which may remove the bias caused by the traditional way of basing on experiences or testing methods to get the characteristic distance. Hence the results from geostatistical analysis can also offer useful information for the determination of sediment sampling density in the future field work.     

地统计法在粒径趋势分析中的应用:以北部湾东部为例(英文)

There are 71 surface sediment samples collected from the eastern Beibu Gulf. The moment parameters (i.e. mean size, sorting and skewness) were obtained after applying grain size analysis. The geostatistical analysis was then applied to study the spatial autocorrelation for these parameters; while range, a parameter in the semivariogram that meters the scale of spatial autocorrelation, was estimated. The results indicated that the range for sorting coefficient was physically meaningful. The trend vectors calculated from grain size trend analysis model were consistent with the annual ocean circulation patterns and sediment transport rates according to previous studies. Therefore the range derived from the semivariogram of mean size can be used as the characteristic distance in the grain size trend analysis, which may remove the bias caused by the traditional way of basing on experiences or testing methods to get the characteristic distance. Hence the results from geostatistical analysis can also offer useful information for the determination of sediment sampling density in the future field work.     

ADCP在长江口悬沙输运观测中的应用

声学多普勒流速剖面仪 (ADCP)是近年来发展起来的一种用于测量流速的声学仪器 ,同时还可以通过建立回声强度和现场取得水样的回归关系式而获得悬沙浓度的数据。本文利用在长江口两个站位的高频观测数据 ,对现场取得的悬沙作粒度分析 ,在此基础上对枯季长江口地区悬沙输送机制和悬沙粒度对水动力的响应进行了分析和探讨。结果表明 :平均流输运在整个悬沙输送中占主导地位 ,同时潮扩散和垂向扩散作用也是引起两站悬沙输运的重要因子 ;不同层次和不同时刻的悬沙粒度参数的变化 ,既和海 陆转换有关 ,也和潮相变化密切相关。     

山东月湖的沉积物分布特征及搬运趋势

1998年 11～ 12月和 1999年 8～ 9月各一个月对月湖进行的野外工作 ,共取得表层沉积物样品 131个 ,应用激光粒度仪并结合传统的筛分法对这些样品进行粒度分析 ,进行矩法计算获得粒度参数。采用Gao命名方法 ,将沉积物划分出 5种主要类型。利用Gao -Collins粒径趋势分析模型 ,计算该区沉积物粒径趋势所显示的沉积物净搬运方向 ,结果表明 ,沉积物从四周向湖中心搬运 ,同时显示湾顶的西部和北部、涨潮三角洲以及湖心等地貌单元是沉积的优势区域。     

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu

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.     

The coast evolution and regulation in Wanquan River Estuary, Hainan Island

In this paper, sediment samples were collected along the Wanquan beaches and sieved in the laboratory in order to obtain the grain size distributions and associated parameters, i.e. mean grain size, sorting coefficient and skewness. Furthermore, we have calculated the longshore drift sediment transport rates and equilibrium cross-sectional areas of the entrance channel by using the method of sedimentary dynamics. The results indicate that the longshore drift sediment transport is dominated by waves with a direction from south to north, which result in rapid changes of the entrance channel. Therefore, some suggestions were proposed for improving the water quality and restoring the ecosystem of estuary. The engineering method includes increasing the sea-route of entrance channel, tidal prism and water exchanges in Shamei Lagoon.     

海南岛万泉河口海岸动态及其整治对策

In this paper, sediment samples were collected along the Wanquan beaches and sieved in the laboratory in order to obtain the grain size distributions and associated parameters, i.e. mean grain size,sorting coefficient and skewness. Furthermore, we have calculated the longshore drift sediment transport rates and equilibrium cross-sectional areas of the entrance channel by using the method of sedimentary dynamics. The results indicate that the longshore drift sediment transport is dominated by waves with a direction from south to north, which result in rapid changes of the entrance channel.Therefore, some suggestions were proposed for improving the water quality and restoring the ecosystem of estuary. The engineering method includes increasing the sea-route of entrance channel,tidal prism and water exchanges in Shamei Lagoon.     

Sediment variability and transport in the littoral area of the abandoned Yellow River Delta,northern Jiangsu

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.