苏北近岸海域表层沉积物粒度及其对环境动力的响应

对2007年9-11月在南黄海辐射沙脊区和江苏北部潮滩采集的表层底质样品进行粒度分析,获得了平均粒径、分选系数、偏态、峰态等粒度参数,并对其进行了聚类分析。结果表明,9 m以浅和20 m以深的样品可归为两种类型的沉积物,而水深9~20 m之间的沉积物两种类型都有,多样性较大。由Gao-Collins粒径趋势分析模型获得的沉积物净输运趋势显示,除外毛竹砂处沉积物有向外海输运的趋势之外,其他外围的断面均显示泥砂向辐射沙洲中心输运,这与历史资料中记录的结果相一致,表明粒径趋势分析适用于大型辐射沙洲海域。根据Sternberg图分析,粒度参数的空间分布是由差异性输运造成,沉积物从射阳河口岸外向大丰潮间带上部输运的过程中,众数粒径几乎全部以悬移质的形式输运,而小庙洪向东灶潮滩上部输运的众数粒径以悬移方式输运的概率只有60%,从而使射阳河口岸外与大丰潮间带上部的沉积物粒度参数相同,而小庙洪与东灶潮间带上部的沉积物粒度参数有显著差异。     

潮滩水流加减速阶段边界层流速剖面的比较

江苏大丰地区潮滩由于水深较浅,潮流、波浪等动力较强,整个水层可视为边界层,其主体部分是对数层,即水流流速在垂向上呈对数分布。在潮流的加减速阶段,流速剖面将可能偏离对数分布,从而使对数剖面法计算出来的边界层参数造成误差。使用MIDAS-400用户化数据采集系统,在大丰潮滩获得了多层流速、浊度等同步高频观测数据,基于修正后的von Karman-Prandtl模型对u-lnz进行回归分析、数据内部一致性分析来定义流速对数剖面并与未修正前经典理论得到的边界层参数进行比较。分析结果表明,修正后的流速剖面更符合实际情况,边界层参数除了受水流加速度的影响外,还和沙纹等因素有关。另外,边界层参数的变化量与特征加速度负相关。     

南黄海苏北近岸西洋水道水沙输运机制分析

基于2008 年3 月份在南黄海辐射沙脊群西洋水道内5 个站位大潮期间的观测数据（包括流速与悬沙质量浓度的垂向剖面）, 利用机制分解法计算了西洋水道内的水与悬沙通量。结果表明, 水体在多数时段内均处于分层向混合过渡的状态, 中下层水体的理查德森数（Ri）与瞬时悬沙输运量中的平均流输沙项及流速的潮周期变化相关项之间存在显...     

近50年来长江入海径流量对太平洋年代际震荡变化的响应

太平洋年代际震荡(Pacific Decadal Oscillation)是类似于ENS0型的具有年代际时间尺度变化的太平洋气候变率.PDO既对长期的气候变化趋势产生扰动,又会对年际变化事件(如ENSO)产生重要影响,可使ENSO事件的频率和强度改变,以致影响到ENSO和季风的关系.通过对百年来的PDO数据进行HHT分...     

胶州湾冲淤灾害地质及环境稳定性分析

通过对胶州湾1936～2002年4期海图的地形对比和1986年、2007年2期Landsat-5TM影像的对比,分析了近70多年来胶州湾的冲淤灾害地质形势。根据胶卅I湾近百年来的沉积速率特征将其冲淤灾害形势划分为9类,结果表明：胶州湾在1936～1963年间总体呈现轻微淤积态势,但显浪-红岛连线以东区域（含沧口水道）以...     

南黄海辐射沙脊群潮汐水道的悬沙输运特征

根据南黄海辐射沙脊群定点站位的流速和浊度数据,利用通量分解方法,分析了潮汐水道的悬沙输运特征和输运机制。结果表明,辐射沙脊群海域潮汐水道中潮流为往复流,悬沙浓度较高,属于强潮流控制的悬沙浓度相对较高的陆架浅海环境;悬沙输运主要受欧拉余流和潮汐捕捉效应控制,再悬浮的沉积物通过平流作用进行输运。其中,陈家坞槽和西洋水道的悬沙输运以潮汐捕捉效应占优,沉积物向潮汐水道外输运,处于冲刷状态;苦水洋水道以欧拉余流输运为主,水道内的再悬浮的沉积物在强潮流作用下向陆输运,主要堆积在蒋家沙和西洋西侧岸滩等浅滩和潮间带上。由此可见,在陆源物质供应减少背景下,南黄海辐射沙脊群内部的物质充当了新的物源,短期内能够维持近岸潮滩和沙脊的持续增长。     

Field observation and analysis of wave-current-sediment movement in Caofeidian Sea area in the Bohai Bay,China

In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom boundary layer （BBL）. Field observations were carried out in the northwest Caofeidian sea area in the Bohai Bay. Near 2 m isobath （under the lowest tidal level）, a tripod system was installed with AWAC （Acoustic Wave And Current）, ADCP （Acoustic Doppler Current Profilers）, OBS-3A （Optical Backscatter Point Sensor）, ADV （Acoustic Doppler Velocimeters）, etc. The accurate measurement of the bottom boundary layer during a single tidal period was carried out, together with a long-term sediment concentration measurement under different hydrological conditions. All the measured data were used to analyze the characteristics of wave-current-sediment movement and the BBL. Analysis was performed on flow structure, shear stress, roughness, eddy viscosity and other parameters of the BBL. Two major findings were made. Firstly, from the measured data, the three-layer distribution model of the velocity profiles and eddy viscosities in the wave-current BBL are proposed in the observed sea area; secondly, the sediment movement is related closely to wind-waves in the muddy coast area where sediment is clayey silt： 1） The observed suspended sediment concentration under light wind conditions is very low, with the peak value generally smaller than 0.1 kg/m^3 and the average value being 0.03 kg/m^3; 2） The sediment concentration increases continuously under the gales over 6-7 in Beaufort scale, under a sustained wind action. The measured peak sediment concentration at 0.4 m above the seabed is 0.15-0.32 kg/m^3, and the average sediment concentration during wind-wave action is 0.08-0.18 kg/m^3, which is about 3-6 times the value under light wind conditions. The critical wave height signaling remarkable changes of sediment concentration is 0.5 m. The results show that the suspended load sediment concentration is mainly influenced by wave-induced sediment suspension.     

几种新型仪器在水文测验中的应用分析

水文测验是水文工作的一个重要组成部分,可为河床演变和各种水利工程的设计提供第一手的资料。新型量测仪器的应用大大提高了水文测验的效率,相对于传统的测验方法,正日益显示出其优势。本文就水文测验中流速、水位、波浪、含沙量、泥沙级配、推移质输沙率等代表性新型仪器做一初步的介绍,并讨论了其中存在的问题和以后有可能发展的方向。     

中国东部舟山群岛的沉积物入海通量（英文）

Knowledge of the sediment flux derived from different sources is critical for interpreting the sedimentary records associated with large river sedimentary systems. For the Changjiang River system, previous studies hardly focused on the sediment load from the adjacent Zhoushan Archipelago(ZA). Based on four prediction models, aiming to improve the understanding of the sediment load from the ZA during the Holocene, we show that the predicted sediment flux of the ZA ranges from ~0.7 to 26.5 Mt·yr~(-1), with an average value of 10.7 Mt·yr~(-1), and the islands with a relatively large area or high relief contribute greatly to the total flux. This sediment load is an order of magnitude lower than that of the Changjiang River, but it is similar to those of the local small rivers. Located in the core area of the southward dispersal path of the Changjiang River plume, the ZA also influences the sediment transport into Hangzhou Bay and over the Zhejiang-Fujian coastal seas. On the Holocene temporal scale, e.g., for the period from 6 ka BP to 2 ka BP, the sediments discharged from the ZA had a considerable effect on the shelf sedimentary system. This study provides evidence for an important role an archipelago can play in terms of sediment supply and transport in coastal and inner continental shelf regions.     

胶州湾沉积环境与潮汐汊道演化特征

研究了胶州湾沉积物输运格局，沉积速率和潮汐汊道演化特征，结果表明，胶州湾口门水道内的悬沙净输运是从湾内指向湾外，湾内水体悬沙浓度终年较低，胶州湾的泥沙来源较少，沉积速率较低。历史上的围垦活动虽造成了纳潮量的减少，但口门过水断面面积并未减小。胶州湾是一个地貌演化缓慢，口站过水断面面积小于均衡状态面积的汊道系统。今后，可应用沉积动力学等方法确定维持港口和航道资源所需的纳潮量，结合纳潮海湾的环境保护和生态建设，定量地确定胶州湾的围垦潜力。