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A UNIFIED ISOSTATIC datum AND ITS APPLICATION IN SEA LEVEL CHANGE RESEARCH

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Science China Chemistry 1992年第11期35卷 1365-1373页

作者：黄立人杨国华胡惠民马青 First Land Deformation Monitoring Centre S.S.B. Tianjin 300180 PRC

The necessity of establishing a Unified Isostatic datum (UID) for studying the sea levelchanges along the coast of China is discussed in this paper. A so-called Coastal Land Ver-tical Movement Isostatic datum (CLVMID) is established based on precise releveling dataperformed from the 1950s to 1980s and some coniunction releveling data with tide stations.All the data consists of about 250,000 km releveling lines and covers the whole mainland ofChina. As examples, datum corrections for sea level changes derived from two tide stationsand recent crustal vertical movement in the Yangtse Delta area relative to the datum aregiven to explain the significance of the isostatic datum in the research of the sea levelchange trend.

关键词： isostatic datum sea level change crustal movement leveling tide gauging

Establishing altitude datum in dynamic deformation areas

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中国有色金属学会会刊：英文版 2005年第S1期15卷 53-57页

作者： GAO Jing-xiang~1, ZHENG Nan-shan~1, YU Xue-xiang~2,LI Xiang-chen~3,GUO Gang-li~1 (1. China University of Mining and Technology, Xuzhou 221008,China 2. Anhui Polytechnic University, Huainan 232001, China 3. Technological Research Institute of Yanzhou Mining Group, Yanzhou 273500, China)

In the high groundwater table mine areas in Eastern China, such as Yanzhou Mining Group, since the rapid development of coal industry, and especially the mining technique of fully-mechanized top-coal caving mining have been used widely, the surface deformation and subsidence becomes more tempestuous and rapider. With the great surface deformation, the rapid deformation of the leveling control network created newly is also resulted. Therefore to establish a high precise altitude datum in dynamic deformation mine areas is one of the key problems to be settled urgently. The theory of altitude datum establishment with GPS technique in dynamic deformation areas due to mining is inquired. Finally a case is given.

关键词： GPS deformation area due to mining altitude datum deformation analysis

Unification of national surveying vertical datum

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中国有色金属学会会刊：英文版 2005年第S1期15卷 9-12页

作者： YIN Xiao-dong~(1, 2), HU Jia-sheng~1, ZHANG Li-hua~2, LI Shu-jun~2 (1. School of Telecommunication, Dalian University of Technology, Dalian 116024, China 2. Department of Ocean Surveying, Dalian Naval Academy, Dalian 116018, China)

The vertical datum of China is composed of leveling datum for heights and chart datum for depths. The determination of national leveling datum and its disadvantages were discussed firstly. The local mean sea level and chart datum with its guarantee rate of navigation safety were studied secondly. The models of unification of national surveying vertical datum, such as optimization model of mean sea level, adoption of New Chinese quasi-geoid of 2000(CQG2000) and time-invariant global geoid were suggested finally.

关键词： vertical datum leveling datum chart datum geoid quasi-geoid

Multiple Ambiguity datum Precise Point Positioning Technique Using Multi-Constellation GNSS: GPS, GLONASS, Galileo and BeiDou

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Positioning 2015年第3期6卷 32-43页

作者： Mahmoud Abd Rabbou Department of Civil Engineering Ryerson University Toronto Canada

Precise Point Positioning (PPP) is traditionally based on dual-frequency observations of GPS or GPS/GLONASS satellite navigation systems. Recently, new GNSS constellations, such as the European Galileo and the Chinese BeiDou are developing rapidly. With the new IGS project known as IGS MGEX which produces highly accurate GNSS orbital and clock products, multi-constellations PPP becomes feasible. On the other hand, the un-differenced ionosphere-free is commonly used as standard precise point positioning technique. However, the existence of receiver and satellite biases, which are absorbed by the ambiguities, significantly affected the convergence time. Between-satellite-single-difference (BSSD) ionosphere free PPP technique is traditionally used to cancel out the receiver related biases from both code and phase measurements. This paper introduces multiple ambiguity datum (MAD) PPP technique which can be applied to separate the code and phase measurements removing the receiver and satellite code biases affecting the GNSS receiver phase clock and ambiguities parameters. The mathematical model for the three GNSS PPP techniques is developed by considering the current full GNSS constellations. In addition, the current limitations of the GNSS PPP techniques are discussed. Static post-processing results for a number of IGS MGEX GNSS stations are presented to investigate the contribution of the newly GNSS system observations and the newly developed GNSS PPP techniques and its limitations. The results indicate that the additional Galileo and BeiDou observations have a marginal effect on the positioning accuracy and convergence time compared with the existence combined GPS/GLONASS PPP. However, reference to GPS PPP, the contribution of BeiDou observations can be considered geographically dependent. In addition, the results show that the BSSD PPP models slightly enhance the convergence time compared with other PPP techniques. However, both the standard un-differenced and the developed multiple ambiguity datum techniques pres

关键词： GNSS PPP GPS GLONASS Galileo BeiDou BSSD Multiple Ambiguity datum

Progresses and Prospects of Marine Geodetic datum and Marine Navigation in China

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Journal of Geodesy and Geoinformation Science 2018年第1期1卷 16-24页

作者： Yuanxi YANG Tianhe XU Shuqiang XUE State Key Laboratory of Geo-information Engineering Xi’an 710054China Xi’an Research Institute of Surveying and Mapping Xi’an 710054China Institute of Space Science Shandong UniversityWeihai 264209China Chinese Academy of Surveying and Mapping Beijing 100830China

Territorial water is a significant part of national sovereignty of China,thus the infrastructures of national space datum and location services should cover the sea areas except for the land areas.China has established relatively complete geodetic coordinate frame in land areas over the past decades,including the lastest developed China Geodetic Coordinate System 2000(CGCS 2000)with its reference frame and the national gravity datum 2000.However,the currently used geodetic infrastructures have not well covered the sea areas of China.The marine geodetic datum and marine navigation technologies need to be further developed and extended to satisfy the national demands of marine environment and resources detection,scientific investigation as well as marine economy development in new era of China.This paper mainly reviews the development and the progress of Chinese marine geodetic datum and marine navigation,analyses related key technologies in establishing our national marine geodetic datum.Some current trends and future directions for independently developing our national marine geodetic datum and marine navigation technologies are discussed.

关键词： marine surveying geodesy datum positioning underwater navigation

Towards a Semi-Kinematic datum for Egypt

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Positioning 2015年第3期6卷 49-60页

作者： Mostafa Rabah Ahmed Shaker Magda Farhan National Research Institute of Astronomy & Geophysics (NRIAG) Cairo Egypt Faculty of Engineering-Shoubra Benha University Cairo Egypt Faculty of Engineering Kafr Elshiech University Kafr Elshiech Egypt

Since 1990, positioning technology has undergone a dramatic improvement in terms of accuracy and accessibility. Prior to 1990, national geodetic datums were considered to be static with fixed coordinates assigned to the datum origin by convention. datum coordinates were dynamic only as a consequence of re-observation and re-adjustment, or localized disturbance. This strategy has been suitable for terrestrial surveys within stable continental areas. The accessibility of Precise Point Positioning “PPP” is now widespread with the provision of free online processing facilities by various geodetic agencies. Such ready accessibility to a global datum has serious implication for this technology with static geocentric datums. The Geocentric datum of Egypt (ITRF1994 Epoch 1996 based on GPS Observation Campaign 1996), for example, is now offset by -42.0 to +32.0cm from the ITRF2008 Epoch 2015 due to the inexorable tectonic movements of the Nubian plate since the datum realization in 1996. Unless the local geocentric datums are kept in step with global terrestrial reference frames, discrepancies between the two will increase in magnitude over time and will become discernable, even using PPP. The PPP users nowadays are unaware of this datum offset and incorrectly assume that a coordinated datum monument is in error if there is found to be a disagreement greater than the level of accuracy of the positioning technique. In this study, to avoid the discrepancies between the applied datum and On-Line GNSS Services, a semi-kinematic datum and related deformation mode are proposed for Egypt. The result also confirmed that the PMM model was giving good performance for the other parts out of Egypt. The evaluation study shows the best performances for the Egyptian deformation model over the ITRF2008 PMM.

关键词： Geodetic datum Precise Point Positioning Plate Deformation Model

Mapping Sea Level Rise Behavior in an Estuarine Delta System：A Case Study along the Shanghai Coast

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Engineering 2018年第1期4卷 156-163页

作者： H.Q. Cheng J.Y. Chen Z.J. Chen R.L. Ruan G.Q. Xu G. Zeng J.R. Zhu Z.J. Dai X.Y. Chen S.H. Gu X.L. Zhang H.M. Wang State Key Laboratory of Estuarine and Coastal Research East China Normal University Shanghai 200062 China Shanghai Water Planning Design and Research Institute Shanghai 200232 China Shanghai Water Authority Shanghai 200050 China School of Urban and Regional Science East China Normal University Shanghai 200062 China School of Ecological and Environmental Sciences East China Normal University Shanghai 200062 China Shanghai Hydrological Station Shanghai 200232 China Shanghai Municipal Bureau of Urban Planning and Land Resources Shanghai 200003 China Shanghai Institute of Geological Survey Shanghai 200072 China

Sea level rise (SLR) is a major projected threat of climate change that is expected to affect developing coastal cities located in estuarine delta regions. Shanghai is one such city, being located in the Yangtze River Delta (YRD). It is difficult, however, for decision-makers to implement adaptation due to the uncertain causes, magnitudes, and timings of SLR behaviors. This paper attempts to map the causes and magnitudes of SLR behaviors on a decadal scale. We analyze the tidal level records from 11 tidal gauge stations and the corresponding bathymetry measurements around these stations since 1921. We identify three new SLR behaviors along the Shanghai coast due to anthropogenic geomorphologic changes (AGCs), besides the well-known eustatic sea level rise (ESLR), tectonic subsidence (TS), and urban land subsidence (ULS). The first new behavior is regional sea level rise (RSLR), which occurs as a result of land reclamation and deep waterway regulation. The second is regional sea level fall (RSLF), which occurs because the channel bed is eroded due to sediment supply decline in the river catchment. The last SLR behavior is local tidal datum rise (LTDR). Thus, we project that the magnitude of SLR for the Shanghai coast ranges from 10 cm to 16 cm from 2011 to 2030. Clarifying SLR behaviors is important to aid local decisionmakers in planning structural and non-structural measures to combat escalating flood damage costs in an estuarine delta system; this field is full of future challenges.

关键词： Sea level rise behavior Anthropogenic geomorphologic change Local tidal datum Flood management Adaptation

Exploration and Sources of Bauxite Deposit in the Boloven Plateau, Southern Laos

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Journal of Earth Science 2019年第1期30卷 121-130页

作者： Yongzhen Long Xiaoyong Yang Mu Yang Dexian Zhang Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring Ministry of EducationCentral South University School of Geosciences and Info-Physics Central South University CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space SciencesUniversity of Science and Technology of China

The Boloven bauxite deposit occurs either in the weathered basalt(alkali basalt and tholeiite), or in the Cretaceous sandstone. It is generally agreed that the bauxite deposits/laterites overlying the alkali basalt and tholeiite were derived from weathering of underlying basalt, however, the origin of bauxite deposit overlying the sandstone remains controversial. Chondrite-normalized REE patterns show that the bauxite ores/laterites overlying the sandstone exhibit quite similar chondrite-normalized REE patterns to those overlying the alkali basalt. Diagram of Al-Ti-Zr shows that the bauxite ores/laterites overlying the sandstone, tholeiite and alkali basalt are close to each other and to the calc-alkaline suite, however, significantly different from the sandstone and shales. Binary diagram of log Nb/Y vs log Zr/Ti further indicates that the parent rocks of bauxite ores/laterites overlying the sandstone belong to the suit of ultra-alkali to alkali basalt. Multivariate statistical analysis of geochemical data exhibit that the geochemical characteristics of HREE, Y, LREE and Al_2O_3 for bauxite ores/laterites overlying the sandstone are similar to those overlying the alkali basalt(15.7 Ma), obviously different from those overlying the tholeiite(1.2 to 0.5 Ma). Consequently, it can be inferred that the bauxite deposits/laterites overlying the sandstone were derived from the alkali basalt.

关键词： late ritic-type bauxite XRD datum processing exploration sources Boloven Plateau Laos

海岸线识别偏差:马来西亚登嘉楼州吉隆坡地区中等潮汐海滩的理论值和测量值

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Journal of Marine Science and Application 2022年第3期21卷 184-192页

作者： Faerah Nasir Adina Roslee Junainah Zakaria Effi Helmy Ariffin Nor Aieni Mokhtar Faculty of Science and Marine Environment Universiti Malaysia Terengganu21030Kuala NerusTerengganuMalaysia Institute of Oceanography and Environment Universiti Malaysia Terengganu21030Kuala NerusTerengganuMalaysia

Shoreline change analysis frequently begins with feature identification through visual interpretation(proxy-based shoreline)or the intersection of a specific tidal zone(datum-based shoreline).Using proxy-based shoreline information,this study quantifies the distance between proxy-based and datum-based shoreline data,which is defined as the proxydatum bias.The study was conducted at meso-tidal beaches in Kuala Nerus,Terengganu,Malaysia,with morphodynamic responses to northeast and southwest monsoons.The high-water line(HWL)shoreline(proxy-based)was determined using ortho-rectified aerial images captured by an unmanned aerial vehicle(UAV).By contrast,the mean high-water(MHW)shoreline(datum-based)was determined using measured beach profiles adjusted with the Peninsular Malaysia Geodetic Vertical datum(DTGSM).The theoretical proxy-datum bias was approximated using the best estimate(median)for the beach slope,wave height,and wave period from the estimated total water level(TWL)model.Based on the study,the recorded horizontal proxy-datum bias for the research area was up to 32 m.This study also discovered that the theoretical assumption of the proxy-datum bias based on the TWL model yields values comparable to those of the measurements,with a narrower distinction in bias for steeper beach slopes than the obtained results.The determined proxydatum bias value can benefit future shoreline change studies as it could be incorporated to either proxy-based shorelines by shifting the shoreline seaward or to datum-based shorelines by shifting the shoreline landward in order of the bias value.The seasonal monsoon’s effect on beach profiles should be considered when calculating bias values and conducting potential shoreline change rate studies.

关键词： Shoreline evolution datum Beach profile Unmanned aerial vehicle Monsoon