长江口徐六泾断面潮流资料整编方法研究

大江大河受潮汐影响的河口水文资料整编，在我国还无较为合适可行的方法，长江口徐六泾水文站建站近１０年，所取得的资料迫切需要有一个归宿。通过对影响长江口徐六泾断面潮流（包括三个方面：潮量，潮平均流量，潮流历时）的多重因子进行的物理成因分析，以及对目前徐六泾断面的实测资料的综合考虑，提出了分不同潮型，不同来水情况对选定的因子进行多元线性回归分析的方法，作为徐六泾断面潮流资料的整编方法，并得出了１９８４年     

长江口徐六泾节点整治工程的影响分析

徐六泾节点整治工程是国务院批复的《长江口综合整治开发规划》的重要组成部分。目前已实施的新通海沙整治工程,使徐六泾节点断面河宽缩窄了近16.3%,对徐六泾河段的河床演变及潮流量产生了一定的影响。在介绍徐六泾节点整治工程的基础上,就整治后徐六泾节点段河床演变和潮流量变化等进行了分析。分析结果表明:整治工程对徐六泾断面形态产生了直接影响,左侧较长的顺长缓坡逐渐冲刷成副槽,原来偏"V"形断面形态向偏"W"形断面形态发展;工程的影响主要位于围堤前沿;徐六泾断面潮流量未见明显减小;徐六泾节点段深槽基本稳定。     

长江口徐六泾节点段河槽稳定性及其影响因素

徐六泾节点段控制着长江口的物质通量和南北支的分流分沙,其河槽稳定性和变化趋势在长江口的演变中具有重要地位。采用实测资料分析和物理模型试验相结合的方法研究了长江口徐六泾节点段河槽的稳定性及其影响因素。研究结果表明:①徐六泾节点段1992年前河槽呈右移态势;1992—2018年间,河槽演变趋缓,平面上主要表现为小幅度的上提下挫,垂向上呈缓慢刷深之势。②徐六泾节点段未来滩槽格局基本稳定,河槽仍以冲刷为主,且有向下游发展趋势,大洪水作用下局部河床会出现较大的调整(2009—2018年+百年一遇水文年试验条件下,在现有的-30 m深槽下游约910 m 处出现一个新的-30 m槽)。③徐六泾节点段河槽整体稳定性前期主要受两岸圈围工程、上下游河势、大洪水等的影响,近年来主要受流域减沙的影响,局部河床稳定性的主要影响因素是大洪水和人类活动。     

长江徐六泾近6年水质变化趋势及其响应机制分析

根据徐六泾水质自动站自2013年1月至2018年10月共303周的水质监测数据,分析了5项水质基本指标(水温、pH值、溶解氧、电导率、浊度)和3项重点监测指标(总有机碳、氨氮、高锰酸盐指数)近6 a的变化趋势。对比了溶解氧、高锰酸盐指数和氨氮3项指标2016年1月至2017年10月的人工监测数据,并采用综合水质标识指数法初步探究了自动监测系统对徐六泾断面水质综合变化的预警响应机制。结果表明:徐六泾断面近6 a水环境质量较好,各指标数值波动幅度逐渐减小;两种监测方式对溶解氧和高锰酸盐指数的检测结果相对偏差≤20%的分别占比100%和84.2%,而对氨氮的检测结果相对偏差≤20%的仅占比42.1%。经分析认为主要是由两种方式的检测方法原理不同所引起的系统偏差。但通过单因子水质评价法进行评价时,两种方式的评价结果仍具有较高的一致性;自动监测系统根据响应机制能够直接反馈徐六泾断面水质综合变化情况。徐六泾水质自动监系统不仅为城市供水提供安全保障,更为保护长江口区域生态环境提供科学依据。     

长江口近十年水质时空演变趋势分析

为了掌握长江口水质污染变化情况,在长江口徐六泾、石洞口、启东港、南港、北港和吴淞口下23公里处6个监测断面,对TN、TP浓度进行了为期13 a的常规监测。监测结果表明:(1)2010年以前,6个监测断面的营养盐浓度年内波动起伏较大,2010年以后进入相对平稳阶段,并呈现逐年下降的趋势。说明自水资源"三条红线"监管制度和区域内各治理项目实施以来,取得了较大的正效应,TN和TP都呈现了年内变幅减小、浓度逐年降低的趋势。(2)由于河口受潮汐影响,各个断面的TN和TP均出现不同程度的丰水期营养盐浓度高于枯水期的情况,并且呈现出丰枯两季营养盐浓度差异逐渐减小的趋势。(3)2009年枯水期为TN沿程变化的分界点,即徐六泾-南港的上升趋势、南港-北港的下降趋势,在2009年之后变为徐六泾-南港的下降趋势,南港-北港的上升趋势。TP的丰枯沿程变化则比较平稳,但有小幅度上升趋势。     

1983年长江口全潮水文测验

为满足长江口开发整治的需要,选择长江干流徐六泾、北支进口段的青龙港和出口段三条港三个断面,于1983年10月13～24日曾进行全潮水文测验,布置如图. 这次全潮测验的项目有水位、流量、含沙量、输沙率、河床质、泥沙颗粒分析、含盐度分析、水温、风向风速等. 潮水位观测共有五组.除徐六泾、     

长江南通河段河演分析及徐六泾节点的作用

徐六泾节点是长江下游最后一个节点，它的功能关系到长江口南河段的发展趋向。为此从徐六泾节点的形成，作用及近期对南支的影响等方面阐述巩固徐六泾节点的重要性。长江南通通河段１９１８年至１９４８年间通洲沙水道的主流动力辆线来回摆动，主次更替，并于１９５７年通过人工措施而并岸，以后逐年围垦，到１９６５年该段长江宽度从１５．７公里缩狭为５．７公里，形成了徐六泾节点。在１９６５年至１９７４年期间，徐六泾节点产生     

徐六泾节点近期水动力形势影响分析及其左岸整治开发初步设想

1 前言 长江口是长江的入海口门,20世纪60年代以来,由于通海沙及江心沙的围垦,附近江面由原来的15.7km缩窄为5.7km,成为一个控制河势的节点,从而把长江河口区由原来的江阴以下移至徐六泾以下。在长江口,由于长江径流和口外潮流这两股强大的动力作用,使得沙洲多变,航道不稳。从徐六泾至海口的鸡骨礁,全长145km,在徐六泾     

长江口河段近期水沙特性研究

由于徐六泾站潮流量和悬移质输沙率测验资料系列不长,代表性不够,尚难用于直接分析,利用徐六泾站近年来取得的水沙资料与大通站同期资料进行相关分析,推定长江口河段的水沙特性及变化情况。结果表明,大通站和徐六泾站的水、沙关系相关性良好,长江口河段近期年径流量和年输沙量的变化趋势与长江上游干流一致,年径流量没有趋势性的变化,而输沙量则呈逐年下降的趋势。长江口河段落潮潮量主要集中在汛期,而涨潮潮量主要集中在非汛期,枯季悬移质泥沙中值粒径粗于洪季。     

三峡工程后长江口徐六泾入海水沙特征变化研究

基于2004-2019年长江口徐六泾断面观测数据，分析了三峡工程修建以来长江入海水沙特征和变化过程。结果表明，三峡水库修建后入海流量年内分配在2010年后出现显著改变，洪季期间的7月流量增大17%,9月减小22%,枯季各月流量升高15%以上。徐六泾多年垂线平均含沙量为0.09 g/L;2010年是徐六泾表层含沙量减少的拐点，减少幅度达50%。2014年以后，徐六泾表中层含沙量呈新一轮下降进一步减少，底层含沙量从2016年开始有所升高，入海含沙量减少趋势放缓。入海泥沙多年平均中值粒径为6.5μm, 2016年以前黏土与粉砂含量之比约为4∶6,砂含量低，之后含砂量平均占比由2%上升到10%,入海悬沙粗化。建坝对入海水通量的年内分配有重要影响，入海泥沙特征变化则受建坝与中下游河流自适应调整的双重影响。     

Calibration of turbidity meter and acoustic doppler velocimetry (Triton‐ADV) for sediment types present in drained peatland headwaters: Focus on particulate organic peat

Suspended sediments have a clear impact on fluvial water quality and aquatic habitats. As the concentrations are highly variable, continuous measurement offers a good way to provide accurate and precise values of sediment concentration and yield. However, there is a lack of information regarding the effect of organic peat particles, which typically appear in boreal fluvial systems. In the present study, the effect of different types of suspended sediments on calibration of a turbidity meter and an acoustic Doppler velocimetry (Triton‐ADV) was studied in laboratory conditions. The measurements were performed using particulate organic peat, clay and silt with several concentrations ranging from clear water to 3500 mg L^?1. The present study primarily provides organic peat sediment calibration data for used sensors. Regression equations were developed for the different sediment. The results indicate that particle size, shape, concentration and sediment type have an effect on calibration. When the turbidity and the ADV calibration were performed for different particle size groups, sediment types and concentrations, the calibration and suspended solids calculation error was reduced. For the turbidity sensor used, the reliable upper continuous measurement limit for clay, peat and silt sediments was found to be at 1000, 2500 and 3500 mg L^?1, respectively. The ADV‐sensor was noticed to be reliable only with fine particles. The results enable easy and first step calibration and error assessment for automatic turbidity and acoustic monitoring of the suspended sediment quality typically present in headwater fluvial systems. This study can be used to evaluate the effect of different sediments on turbidity and ADV‐measuring error and reliability during changing particles size distributions, characteristics and concentrations. The laboratory‐based approach used in this study indicates that the shape of organic peat particles has an influence on sensor calibration, especially when suspended sediment concentrations are high. Copyright © 2009 John Wiley & Sons, Ltd.     

三峡工程混凝土质量声波波速标准研究

通过对不同设计标号、龄期、级配的混凝土试件抗压强度和声波速度的比较试验,结合现场混凝土声波测试,讨论了混凝土强度、龄期、级配、测孔间距等因素对混凝土波速的影响,并根据现行相关混凝土质量验收规范,提出了三峡工程混凝土质量声波波速标准。通过在三峡工程混凝土质量检测中的实际应用,认为该标准是可行的。     

微生物胶结砂体巴西劈裂试验声发射特性的细观模拟

针对微生物胶结砂体已取得一定研究成果,但关于其材料的细观变形特征和破裂过程尚不清晰。采用离散单元法并引入矩张量理论,构建微生物胶结砂体在巴西劈裂试验中的细观模型,研究其声发射特性。研究结果表明:在试样劈裂过程中,随着应变的逐渐增大,破裂强度从试样顶部和底部开始沿中轴线扩展,且破裂强度的数值不断增大,最终形成主要沿试样中轴线的宏观破裂带;声发射事件比率与破裂强度服从正态分布,且破裂强度分布在-7. 52和-5. 79之间;声发射事件次数与微破裂数近似呈负指数函数关系。研究成果为探明微生物胶结砂体的破裂过程提供了新的思路。     

Soundpeaking – Hydropeaking induced changes in river soundscapes

Underwater soundscapes and their unique acoustic signatures are mainly generated through movement of streambed sediment, subsequent particle collisions, and turbulence created by water flowing over submerged obstructions such as rocks and woody debris. This study characterized river soundscapes in Alpine rivers of Trentino, (North East Italy) with the combined use of hydrophones and a new microelectricalmechanical systems based device (Hydroflown) that is capable of measuring particle velocity components of the sound field. Pool and riffle habitats affected and unaffected by hydropeaking were characterized in terms of their particle velocity and sound pressure levels across 10 octave bands (acoustic signature) to assess temporal variations in overall sound levels, changes in frequency composition, and relationship to hydromorphological habitat parameters. Data revealed that soundscapes affected by hydropeaking are highly homogenized, and sound pressure levels are strongly correlated with turbine discharge, which results in rapid, multiple‐fold spikes in low frequency amplitude levels within the typical hearing range of common teleost fish species. The outcomes of this study provide the basis for further examination of the resulting behavioural and physiological responses of organisms to anthropogenic changes in river soundscapes.     

岩石破坏声发射b值的误差分析

岩石声发射b值变化是岩石破坏的重要前兆之一,由于b值大小受到样本数、起算幅值和幅值间隔等人为设定的影响,开展b值误差量化分析意义重大。采用不同的样本数、起算幅值和幅值间隔,使用最大似然法和最小二乘法计算由随机数组成的岩石声发射幅值目录的b值,将结果中分布在误差以内的数据记为有效数据,使用有效数据占比分析了b值误差大小,并使用室内花岗岩三轴压缩的声发射幅值目录对其进行了验证。结果表明:使用最大似然法计算岩石声发射b值时,有效数据占比随着样本数的增加而减少,随着起算幅值的增大而增加。使用最小二乘法估计b值时,随着样本数的增加,有效数据占比先增后减,样本数为2 000个左右时可得到最多的有效数据;幅值间隔一定时,起算幅值越大,有效数据占比越小;随着起算幅值的增加,对应的取得最多有效数据的幅值间隔从22 dB减少到18 dB。研究成果可为岩石破坏声发射b值的合理计算提供参考。     

Sediment distribution and accumulation in Lake Naivasha,Kenya over the past 50 years

Although surface waterbodies are water sources for socio‐economic activities and ecosystems, their functions are threatened by sedimentation. Sedimentation of lakes and reservoirs can result in a loss of storage capacity and altered water quality. The present study assessed the sedimentation status of Lake Naivasha, Kenya, based on sediment distribution and accumulation over the past 50 years, using a Bathymetric Survey System (BSS). The BSS uses multi‐frequency Acoustic Profiling System (APS) to map recently deposited sediments. Sediment core samples were collected with a vibe‐ coring device and dated. Sediment layers corresponding to a period of the past 20 and 50 years were identified. Sediment cores and acoustic images were subsequently used to determine sediment thickness within the lake. The collected depth data from multi‐frequency APS, and dated cores were processed in DepthPic and Surfer software. The sediment depth was extracted in DepthPic, while the sediment volume and distribution were generated from Surfer software. The results from present study indicated that sediment distribution varied from one part of the lake to another for the past 20 and 50 years. High sediment thickness observed in the south‐west and eastern parts of the lake. Between 1996–2016 and 1966–2016 periods, the maximum accumulated sediment thickness was found to be about 0.55 and 1.9 m, with an average sediment thickness of 0.25 and 0.56 m, respectively. The mean sediment load corresponding to the 1966–1996 and 1996–2016 periods was 2.78 × 10⁵ and 4.61 × 10⁵ t/year, respectively. It was found that sediment load into Lake Naivasha has been increasing in the recent past. Based on the present the study, it was found that combined use of BSS, sediment cores and dating can be adopted in many lakes and reservoirs to determine sediment thicknesses even where no prior bathymetric surveys exist for comparison.     

Modeling and analysis of effects of precipitation and vegetation coverage on runoff and sediment yield in Jinsha River Basin

This paper focuses on the effects of precipitation and vegetation coverage on runoff and sediment yield in the Jinsha River Basin. Results of regression analysis were taken as input variables to investigate the applicability of the adaptive network-based fuzzy inference system (ANFIS) to simulating annual runoff and sediment yield. Correlation analysis indicates that runoff and sediment yield are positively correlated with the precipitation indices, while negatively correlated with the vegetation indices. Furthermore, the results of stepwise regression show that annual precipitation is the most important factor influencing the variation of runoff, followed by forest coverage, and their contributions to the variation of runoff are 69.8% and 17.3%, respectively. For sediment yield, rainfall erosivity is the most important factor, followed by forest coverage, and their contributions to the variation of sediment yield are 49.3% and 24.2%, respectively. The ANFIS model is of high precision in runoff forecasting, with a relative error of less than 5%, but of poor precision in sediment yield forecasting, indicating that precipitation and vegetation coverage can explain only part of the variation of sediment yield, and that other impact factors, such as human activities, should be sufficiently considered as well.     

长江口细颗粒悬沙浓度垂向分布

在长江口利用“声学悬沙观测系统”观测到大潮四种典型的高时空分辨率细颗粒悬沙浓度声学向分布图和垂线分布曲线，悬沙垂线分布曲线表明：（１）在涨潮地１形，沙２的垂向变化梯度小。（２）在涨急时呈射流形射流顶的悬沙分布达１０ｇ／Ｌ悬浙江省 浓度的垂向变化梯度大。（３）在落潮时从水面到水底悬沙浓度按指数增加，可能代表恒定均流中悬沙处于平衡条件的分布，泥沙垂各扩散系数εＳ在数值上大约是泥沙颗粒沉降速度ωＳ的两部     

实时高温下北山花岗岩劈裂试验及声发射特性

为了探究实时高温条件下岩石试样的拉伸试验和全过程声发射特性,采用MTS810电液伺服试验系统,进行了不同实时温度下核废料预选区北山花岗岩试样巴西劈裂试验,比较分析不同温度(25～1 000 ℃)下北山花岗岩宏微观的破坏特征、荷载-位移曲线、抗拉强度以及全过程声发射特征随温度的演化规律等。研究结果表明:随着温度的升高,北山花岗岩形成的裂缝越来越多,晶间裂纹的裂缝孔径逐渐增大,T> 400 ℃时形成明显的穿晶裂缝,失效模式也从脆性的拉伸破坏变为延性,呈Y型破裂模式;荷载-位移曲线形状由“下凹”型向“上凸”型转变,实时高温下北山花岗岩抗拉强度整体呈下降趋势,这种随温度的劣化趋势却表现出较强的阶段性特征;达到峰值荷载之前声发射(AE)事件存在平静期,随着温度的增加,这种平静期阶段变得越来越不明显,同时峰值振铃计数率逐渐减小。研究成果可供深部地下实验室建设和数值模拟提供参考。     

输沙量差法计算河道冲淤量的误差分析

输沙量差法是计算河道冲淤量的主要方法之一。分析了输沙量差法与断面法计算河道冲淤量结果之间的差异和采用输沙量差法计算河道冲淤量的误差来源,提出了计算河道冲淤量中误差和相对误差的表达式。结合黄河下游现行测量条件,指出：①河道输沙量测验的相对中误差为1．7％～2．5％,能满足了解河道输沙情况的要求;②一般情况下河道冲淤量的绝对值远小于输沙量,但其绝对误差又大于输沙量的测验误差,导致计算的河道冲淤量的相对误差较大;③河段冲淤量的相对误差随冲淤量的减少而增加,甚至出现实测的冲淤量小于其测量误差,导致冲淤量计算成果定性困难;④当河道内的冲刷量或淤积量占来沙量的比例较大时计算的冲淤量相对误差很小,但河段淤积率降低到一定程度时,冲淤量的相对误差迅速增大,甚至超过100％,此时采用输沙量差法计算的河道冲淤量无使用价值。