利用跨海水准测量实现岛屿间的高程传递

结合2015年某海洋测绘任务特点,对跨海水准测量的误差来源进行了认真分析,做出了利用跨海水准测量实现岛屿间高程传递的技术方案设计。针对跨海水准测量存在的3种重要误差来源,利用辅助设备测量全站仪和觇板高度、适当增加测角测回数提高垂直角测量精度、精心策划测量步骤减小大气垂直折光误差等手段,有效消除和减小了误差项影响,最后通过平差得到了高差单位权中误差为±2.69mm的测量成果,满足了三等水准测量要求,实现了海洋岛屿间的大跨度高程传递。     

超长距离跨海二等水准测量的数据处理与应用

为验证改进的精密三角高程法在10km级超长距离跨海二等水准测量的可行性,参照规范的观测要求和限差规定,采取每时段分组观测的方法,通过合理限制各组间的高差互差值来筛选出合格测段,计算得到跨海段的高差值。以15km的海湾构成跨海大地四边形进行应用试验,结果表明跨海高差与陆地常规水准高差之间的互差值分别为1.5、0.2、1.3、0.7cm,成果满足国家二等水准测量精度要求。该方法能为10km级超长距离的高等级跨海水准测量提供应用参考。     

跨海高程传递三角高程数据处理及质量分析

对跨河水准测量和跨海高程传递三角高程测量的观测方法和数据处理进行了比较.简单介绍了4处跨海高程传递测区的概况,并提出一种针对“光段差互差”的评估方法.对4处跨海点三角高程实测数据进行质量分析和平差计算,结果表明:除实验区外,跨海三角高程测量的偶然中误差可以达到二等水准测量的精度;数据质量分析结果表明,满足二等水准限差的外业观测数据的有效率为50％左右;满足三等水准限差的数据有效率为90％左右.     

远距离跨海水准测量——平潭海峡大桥两岸高程传递

本文介绍了平潭海峡采用了较先进的测距三角高程法和计算理论。完成距离长达3478m跨海三等水准测量。通过改造观测觇板、提高照准精度、运用两个大地四边形的布网形式,构成一个以跨海测线为主的具有外部检核条件的水准闭合环;通过间接测量仪器高、间接计算高差、间接求两差改正数的方法,取得了远距离跨海水准测量的一些成功经验。     

同步验潮法在刘公岛跨海高程传递中的应用

阐述了短期同步验潮法在跨海高程传递测量中的基本原理与应用,通过试验介绍了短期同步验潮法传递高程的实施流程与数据处理。根据短期同步验潮法在山东省刘公岛跨海高程传递测量中的试验,结果表明,在短距离跨海时,短期同步验潮法能达到三等以上水准测量精度要求。     

远距离海岛礁高程基准统一方法研究

综合利用水准测量和卫星定位测量,给出了基于三角高程测量的高精度远距离海岛礁高程基准的统一方法和实施方案。利用我国沿海12处海岛的跨海高程基准统一方法、测量方案、技术手段、数据处理要求和实测数据,对远距离海岛礁高程基准统一的经验做法、成果精度和数据质量进行了分析和总结,并针对此方案给出了一些跨海三角高程需要注意和值得借鉴的参考意见。     

远距离海岛礁高程基准统一方法研究

综合利用水准测量和卫星定位测量,给出了基于三角高程测量的高精度远距离海岛礁高程基准的统一方法和实施方案.利用我国沿海12处海岛的跨海高程基准统一方法、测量方案、技术手段、数据处理要求和实测数据,对远距离海岛礁高程基准统一的经验做法、成果精度和数据质量进行了分析和总结,并针对此方案给出了一些跨海三角高程需要注意和值得借鉴的参考意见.     

简讯

宁波大榭跨海公铁两用大桥已于今年4月19日奠基,计划于1999年6月底建成通车。 大榭岛紧邻大陆,最近处仅600米,已建成通车的大榭跨海钢铁浮桥使海岛与大陆连成一体,即将动工兴建的大榭跨海公铁两用大桥是连接宁波市北仑区和大榭岛主要通道,跨海     

基于Windows CE水准测量应用软件的设计与实现

根据水准测量实际问题，抽象出水准测量应用软件的需求与功能，在此基础上，利用基于Windows CE应用软件开发工具——eMbedded Visual Basic，设计和开发了水准测量应用软件。该系统利用EVB提供的强大的可视化功能，为用户创建窗体式程序界面，使用中通过窗体的相互调用，完成用户对水准测量外业记簿、检核和平差计算的基本需求。     

DL101C数字水准仪在二等水准测量中的精度分析

介绍了数字水准仪的测量原理,根据工作经验提出了使用数字水准仪进行高精度水准测量应注意的若干问题,将DL101C数字水准仪应用于二等水准测量任务并对其测量精度进行了分析。结果表明,该数字水准仪具备较高的测量精度,能够很好的用于高精度水准测量。最后提出了一些实际作业中的使用建议。     

Quasi-Geoid Near Xisha Islands by the Geo-Potential Propagating Technique

Height datum is an important part of national geodetic network. Establishment of a unified national land and sea elevation benchmarks and implementation of height datum connection between the Chinese mainland and offshore islands are issues that need to be resolved in geomatics and marine sciences. Derived from basic definition of elevation datum and relationship between geo-potential and normal height, the scientific theory and algorithm for transferring height datum from mainland to islands with geo-potential are elaborated. The accuracy of geo-potential difference is discussed using a numerical analysis method. We also give criteria to choose virtual leveling routines and algorithm to give optimized results. One experiment in the China seas, among 26 tidal gauge stations in the sea coast of the mainland with known normal height, has confirmed the reliability and accuracy of the method developed in this paper. Further optimizations for improving accuracy of island elevation are also introduced. Distribution of quasi-geoid near Xisha Islands is also given with this method.     

短期同步验潮高程传递精度分析

短期同步验潮具有操作简单、容易实施的优点,可以达到厘米级高程传递精度,是一种非常有效的高程传递技术。利用国家海岛(礁)测绘工程临时验潮站水深测量数据,对相距较远的验潮站之间海水面变化的相关性进行了分析研究,给出了部分海岛同步验潮水深、水深差以及水深差与均值之差的变化规律和波动幅度,通过与三角高程的高差结果比较,外符合核精可达到5cm,对于利用短期同步验潮实现高程传递的工程实践具有重要的参考作用。     

一种新的潮滩高程观测方法

利用GPS-RTK技术，结合上海和苏北潮滩高程观测实践。提出利用现场实测潮位，结合岸上水准点建立RTK水准控制网，对潮滩的高程进行有效观测的新方法，并对观测结果进行验证与分析。结果表明，1）流动站与基准站距离在8km范围内，其测量结果的相对误差小于5％；2）该方法简便、易行，特别适合缺少水准点的潮滩地区；3）RTK技术与传统滩面高程观测方法有机结合，取长补短，为潮滩冲淤变化研究和海岸工程监测提供了一个全新手段，具有较大的推广价值。     

江苏岸外辐射沙洲区沙岛形成过程的初步研究

江苏岸外辐射沙洲曾经历了由暗沙到明沙的发育过程，进入20世纪90年代后，近岸的沙洲由于持续淤高并高出大潮平均高潮位而成为沙岛。通过卫片判读和实地观测对沙岛自然属性和形成机制进行了初步研究，认为条子泥西部多年来的持续淤积和潮沟的稳定是沙岛形成的关键，而潮汐和风暴潮是沙岛形成的动力因素。沙岛的形成说明辐射沙洲的发育进入一个新阶段即成岛阶段，并标志着沙洲并陆过程的开始。     

高含沙量岛屿海域冲刷槽的成因及其建港意义——以杭州湾湾口北部洋山海域为例

采用 1999年 1～ 2月实测水文泥沙资料 ,1996年 10月底质调查资料以及 1998年水下地形测图 ,对洋山海区岛屿间水流、泥沙及水下地貌特征进行研究。分析表明 ,洋山海域属淤泥质海岸带的中等潮差近岸水域 ,缘于基岩为主体的岛屿与大流速的水流间的相互作用 ,其基本特征为大流速、多通道、高含沙量以及浅滩 (岛屿 )与深槽间布的水下地形 ,从潮量对比看 ,其主要潮汐通道南北岛链间通道为涨、落潮流共同作用且以落潮流为主的通道 ,小洋山 -镬盖塘通道为涨潮流通道 ,镬盖塘 -大岩礁通道为落潮流通道。基于以上认识 ,港口整体布局类型可分为人工岛型和单通道型 ,而布置起步工程时 ,应注意其附近小洋山 -镬盖塘通道以涨潮流为主的特性 ,为减少对原始流场影响 ,以布置在小洋山岛西南侧为佳。     

人工岛对沙质海岸动力泥沙环境及岸滩冲淤演变的影响研究

基于历史海图、历史时期卫星遥感影像、2019年实测水下地形和潮流、波浪数值模拟成果,研究该海域岸滩的发育演变背景、海床和岸线自然冲淤动态、动力泥沙环境及岸滩冲淤动力机制。采用LITLINE岸线演变数学模型,模拟计算了不同离岸距离和不同平面形态人工岛布置型式对近岸岸线变形的影响,岸滩泥沙动力机制和岸滩演变趋势表明,人工岛实施后近岸最大潮流流速小于近岸泥沙起动流速,不具备起动近岸岸滩泥沙的基本条件; SSE向波浪作用时,人工岛西北侧波高明显减弱,波向西偏; S向波浪作用时,人工岛北侧波高明显减弱; SSW向波浪作用时,人工岛东北侧波高明显减弱,波浪传播方向东偏;波浪场改变后人工岛掩护区东西两侧岸滩附近泥沙分别具有向东和向西运移至人工岛掩护区的趋势,形成掩护区的淤积和东西两侧岸线冲刷。     

Route height connection across the sea by using the vertical deflections and ellipsoidal height data

Distance between the main land and island is so long that it is very difficult to precisely connect the height datum across the sea with the traditional method like the trigonometric leveling,or it is very expensive and takes long time to implement the height transfer with the geopotential technique.We combine the data of GPS surveying,astro-geodesy and EGM2008 to precisely connect the orthometric height across the sea with the improved astronomical leveling method in the paper.The Qiongzhou Strait is selected as the test area for the height connection over the sea.We precisely determine the geodetic latitudes,longitudes,heights and deflections of the vertical for four points on both sides across the strait.Modeled deflections of the vertical along the height connecting routes over the sea are determined with EGM2008 model based on the geodetic positions and heights of the sea segmentation points from DNSC08MSS model.Differences of the measured and modeled deflections of the vertical are calculated at four points on both sides and linearly change along the route.So the deflections of the vertical along the route over the sea can be improved by the linear interpolation model.The results are also in accord with those of trigonometirc levelings.The practical case shows that we can precisely connect the orthometric height across the Qiongzhou Strait to satisfy the requirement of order 3 leveling network of China.The method is very efficient to precisely connect the height datum across the sea along the route up to 80 km.     

基于水准测量技术的填海人工岛沉陷监测实践

近年来随着填海人工岛的增多,其安全性备受关注。人工岛吹填区域软土地基物理力学参数差异大,地面沉陷持续时间长、成因机制复杂和防治难度大,沉陷监测工作具有重要意义。利用精密水准测量技术,通过长期跟踪监测,分析了人工岛吹填区域的变形特征,综合评估了沉降稳定性,为人工岛的环境保护、后续设计施工建设提供科学决策依据。     

Evolution of Jiuduansha Shoal and Its Influence on Adjacent Channels in the Changjiang Estuary

-Based on historic topographic maps and field surveys,this paper mainly deals with the forma-tion and evolution of the Jiuduansha Shoal and the North Passage and South Passage in the ChangjiangEstuary.Jiuduansha Shoal originated from the partition of the south part of the Tongsha Shoal as the re-sult of connection of a flood channel and an ebb channel.The embryo of the North Passage was a floodchannel,and that of the South Passage was the lower reaches of the former South Channel.There weretwo basic kinds of change in erosion and accumulation since the formation of Jiuduansha Shoal:continu-ous change and periodic change.The former includes the broadening of the island area,accretion on thetidal marsh and tidal flat and downstream migration of the island.The latter includes cyclic erosion andaccumulation on the two river channel banks of the island and the North and South Passages.The islandand the two bifurcated river Passages interacted on each other in erosion and accumulation changes.Atpresent,the cou     

The influence of tides,wind and waves on the redistribution of nourished sediment at Terschelling,The Netherlands

A calibrated morphodynamic model of the barrier island of Terschelling, The Netherlands [Grunnet, N.M., Walstra, D.J.R., Ruessink, B.G., 2004. Process-based modelling of a shoreface nourishment. Coastal Eng. 51/7, 581–607], comprising the island and its two adjacent tidal inlet systems, is applied to identify the relative contribution of tides, wind and waves to the cross-shore and alongshore redistribution of a 2 Mm³ nourishment supplied to the nearshore zone along the island. Several model simulations with varying combinations of horizontal and vertical tide, wind and wave forcing were designed to investigate the effect of each individual forcing on a large spatio-temporal scale (order of kilometres and months, respectively). As expected, stirring and transport by waves and wave-induced currents are predicted to be by far the dominant contributor to the net sediment transport along the coast of Terschelling. Because of the strong obliquity of the winds and the relatively small tidal currents in front of the island (≈ 0.5 m/s), alongshore wind-driven currents increase sediment transport rates and horizontal tides virtually have no net transport capacity. This motivated a local model of the study area along the closed coast of Terschelling, not including tidal inlets and further simplifying tidal boundary definitions by omitting the horizontal tides: morphodynamic simulations of the local model show virtually identical results as the larger model predictions. The reduction in complexity in setting up a local model instead of a regional model coupled with the corresponding significant reduction in computational time points to an increasing applicability of complex process-based models.