Journal articles: 'Hydrographic'

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Foroutan, Mina, Sonja Bhatia, and Geneviève Béchard. "The Hydrographer of the Future - Reflections on an international virtual workshop." International Hydrographic Review 28 (November 1, 2022): 172–80. http://dx.doi.org/10.58440/ihr-28-n12.

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The Canadian Hydrographic Service (CHS) expects the skillsets of its multidisciplinary hydrographers to evolve as the field of hydrography undergoes a digital transformation. To characterize these changes, the CHS organized a virtual workshop titled Hydrographer of the Future, in which it heard the perspectives of international colleagues in other Hydrographic offices (HO’s), industry, and academia. Despite some variations, common themes emerged: the changing technological context, people and culture, and the future role of hydrography. The results of this workshop support the CHS’ own internal planning; however, the CHS also hopes to continue learning from its international partners and share its experiences through the International Hydrographic Organization’s (IHO) e-learning center.

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Nakabayashi, Shigeru. "East Asia Hydrographic Commission - Fifty Years of Progress." International Hydrographic Review 27 (May 1, 2022): 99–112. http://dx.doi.org/10.58440/ihr-27-n06.

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The year 2021 marks the 50th anniversary of the East Asia Hydrographic Commission (EAHC). It was established in 1971 as the third oldest Regional Hydrographic Commission located in East Asia. Since then, EAHC has progressed in cooperation of hydrographic services and in development of hydrographic technology for navigation safety and other aims. This article describing comprehensive historical steps and efforts of a Regional Hydrographic Commission in an important area of maritime transport will present readers a suggestive model of regional cooperation in hydrography. One of the suggestions can be summarized that the keys to development of Regional Hydrographic Commission are strong intention, initiative, unity and enthusiasm to leave no one behind.

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Urbahs, Aleksandrs, Rima Mickevičienė, Vasilij Djačkov, Kristīne Carjova, Valdas Jankūnas, Mindaugas Zakarauskas, Natalia Panova, and Dita Lasmane. "Analysis of an Unmanned Aerial Vehicle Monitoring System for Resurveying of Shipping Routes." Transport and Aerospace Engineering 3, no. 1 (December 1, 2016): 102–11. http://dx.doi.org/10.1515/tae-2016-0012.

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Abstract The paper gives brief description of the conventional and innovative hydrography survey methods and constraints connected with the realization. Proposed hydrographic survey system based on the use of Unmanned Aerial and Maritime systems provides functionality to conduct hydrographic measurements and environment monitoring. System can be easily adapted to fulfil marine safety and security operations, e.g. intrusion threat monitoring, hazardous pollutions monitoring and prevention operations, icing conditions monitoring.

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Samsonov, Timofey E. "Automated Conflation of Digital Elevation Model with Reference Hydrographic Lines." ISPRS International Journal of Geo-Information 9, no. 5 (May 20, 2020): 334. http://dx.doi.org/10.3390/ijgi9050334.

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Combining misaligned spatial data from different sources complicates spatial analysis and creation of maps. Conflation is a process that solves the misalignment problem through spatial adjustment or attribute transfer between similar features in two datasets. Even though a combination of digital elevation model (DEM) and vector hydrographic lines is a common practice in spatial analysis and mapping, no method for automated conflation between these spatial data types has been developed so far. The problem of DEM and hydrography misalignment arises not only in map compilation, but also during the production of generalized datasets. There is a lack of automated solutions which can ensure that the drainage network represented in the surface of generalized DEM is spatially adjusted with independently generalized vector hydrography. We propose a new method that performs the conflation of DEM with linear hydrographic data and is embeddable into DEM generalization process. Given a set of reference hydrographic lines, our method automatically recognizes the most similar paths on DEM surface called counterpart streams. The elevation data extracted from DEM is then rubbersheeted locally using the links between counterpart streams and reference lines, and the conflated DEM is reconstructed from the rubbersheeted elevation data. The algorithm developed for extraction of counterpart streams ensures that the resulting set of lines comprises the network similar to the network of ordered reference lines. We also show how our approach can be seamlessly integrated into a TIN-based structural DEM generalization process with spatial adjustment to pre-generalized hydrographic lines as additional requirement. The combination of the GEBCO_2019 DEM and the Natural Earth 10M vector dataset is used to illustrate the effectiveness of DEM conflation both in map compilation and map generalization workflows. Resulting maps are geographically correct and are aesthetically more pleasing in comparison to a straightforward combination of misaligned DEM and hydrographic lines without conflation.

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Haslam, David. "The Duke of Edinburgh Lecture: International Hydrography." Journal of Navigation 46, no. 2 (May 1993): 159–73. http://dx.doi.org/10.1017/s0373463300011516.

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It is perhaps appropriate, on this the exact 187th anniversary of the death of Admiral Lord Nelson at Trafalgar and in the year in which so many celebrations have taken place to commemorate the 500th anniversary of Christopher Columbus's arrival somewhere in the West Indies, to consider the progress which has been made towards international co-operation and achievements in hydrographic surveying and nautical cartography, particularly since the formation of the International Hydrographic Bureau in 1921, and to look at the problems facing international hydrography in the immediate future.

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Atkinson, Larry P., Thomas N. Lee, Jackson O. Blanton, and Gustav-Adolf Paffenhöfer. "Hydrographic observations." Progress in Oceanography 19, no. 3-4 (January 1987): 231–66. http://dx.doi.org/10.1016/0079-6611(87)90010-3.

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Akpınar, Burak, and Nedim Onur Aykut. "Determining the Coordinates of Control Points in Hydrographic Surveying by the Precise Point Positioning Method." Journal of Navigation 70, no. 6 (May 24, 2017): 1241–52. http://dx.doi.org/10.1017/s0373463317000236.

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After Global Navigation Satellite Systems (GNSS) were first used in the field of hydrography in 1980, developments in hydrographic surveying accelerated. Survey precision in hydrography has been improved for both horizontal and vertical positioning and seafloor acoustic measurement by means of these new developments. Differential Global Positioning System (DGPS), Real Time Kinematic (RTK) and Network RTK (NRTK) techniques are the satellite-based positioning techniques that are commonly used in shallow water surveys and shoreline measurements. In line with these developments, the newer Precise Point Positioning (PPP) has been introduced. Combining precise satellite positions and clocks with dual-frequency GNSS data, PPP can provide position solutions from the centimetre to decimetre level. In this study, the coordinates of control points were determined by using the Post-Process PPP (PP-PPP) technique. Seven test points, which are the points of the Continuously Operating Reference Station - Turkey (CORS-TR) network, are selected near the shorelines within Turkey. The 24-hour data was split from one to six hours by one hour periods. Automatic Point Positioning Service (APPS) was selected to process the data. The poisoning error of the test points were given and compared with International Hydrographic Organization (IHO) S44 hydrographic survey standards.

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Specht, Cezary. "Maritime DGPS System Positioning Accuracy as a Function of the HDOP in the Context of Hydrographic Survey Performance." Remote Sensing 15, no. 1 (December 20, 2022): 10. http://dx.doi.org/10.3390/rs15010010.

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The Differential Global Positioning System (DGPS) is a marine navigation system operating at frequencies of 283.5–325 kHz, which is now the primary method for locating vessels in coastal shipping, as well as hydrography and mapping systems worldwide. Its positioning accuracy is determined by the following: the pseudorange error to Global Positioning System (GPS) satellites, the age of pseudorange corrections, and the value of the Horizontal Dilution Of Precision (HDOP), which, in terms of accuracy, is crucial in positioning using GPS satellites. In 2020, the International Hydrographic Organization (IHO) introduced a new (the highest) order of hydrographic surveys, i.e., the Exclusive Order, which requires a positioning system to provide an accuracy of 1 m (p = 0.95). The aim of this article is to provide an answer to the question as to whether the maritime DGPS system, whose positioning accuracy is constantly increasing with that of the GPS system, fulfils the requirements for the hydrographic surveys of harbours. To this end, an extensive experimental study on the maritime DGPS system, involving a total of nearly 3.5 million fixes, was conducted. Statistical analyses showed that when ensuring the HDOP values range from 0.8 to 1.4, the DGPS system can be used in hydrographic surveys of harbours.

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Voss, Rüdiger, Hans-Harald Hinrichsen, Daniel Stepputtis, Matthias Bernreuther, Bastian Huwer, Viola Neumann, and Jörn O. Schmidt. "Egg mortality: predation and hydrography in the central Baltic." ICES Journal of Marine Science 68, no. 7 (May 24, 2011): 1379–90. http://dx.doi.org/10.1093/icesjms/fsr061.

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Abstract Voss, R., Hinrichsen, H-H., Stepputtis, D., Bernreuther, M., Huwer, B., Neumann, V., and Schmidt, J. O. 2011. Egg mortality: predation and hydrography in the central Baltic. – ICES Journal of Marine Science, 68: 1379–1390. Cod and sprat are the dominant fish species in the Baltic pelagic ecosystem, both of great economic importance and ecologically strongly interlinked. Management of both species is challenged by highly variable recruitment success. Recent studies have identified predation and hydrographic conditions during the egg phase to be of critical importance. Two years of extensive field investigations in the Bornholm Basin, central Baltic Sea, were undertaken. In 2002, a typical stagnation situation characterized by low salinity and poor oxygen conditions was investigated, and in early 2003, a major inflow of North Sea water completely changed the hydrographic conditions by increasing salinity and oxygen content, thereby altering ecological conditions. The goal was to quantify egg mortality caused by predation and hydrography, and to compare these estimates with independent estimates based on cohort analysis. Results indicated high intra-annual variability in egg mortality. Cod and sprat egg mortality responded differently to the major Baltic inflow: mortality related to hydrographic conditions increased for sprat and decreased for cod. On the other hand, predation mortality during peak spawning decreased for sprat and increased for cod.

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Stanislawski, Lawrence V., Ethan J. Shavers, Shaowen Wang, Zhe Jiang, E. Lynn Usery, Evan Moak, Alexander Duffy, and Joel Schott. "Extensibility of U-Net Neural Network Model for Hydrographic Feature Extraction and Implications for Hydrologic Modeling." Remote Sensing 13, no. 12 (June 17, 2021): 2368. http://dx.doi.org/10.3390/rs13122368.

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Accurate maps of regional surface water features are integral for advancing ecologic, atmospheric and land development studies. The only comprehensive surface water feature map of Alaska is the National Hydrography Dataset (NHD). NHD features are often digitized representations of historic topographic map blue lines and may be outdated. Here we test deep learning methods to automatically extract surface water features from airborne interferometric synthetic aperture radar (IfSAR) data to update and validate Alaska hydrographic databases. U-net artificial neural networks (ANN) and high-performance computing (HPC) are used for supervised hydrographic feature extraction within a study area comprised of 50 contiguous watersheds in Alaska. Surface water features derived from elevation through automated flow-routing and manual editing are used as training data. Model extensibility is tested with a series of 16 U-net models trained with increasing percentages of the study area, from about 3 to 35 percent. Hydrography is predicted by each of the models for all watersheds not used in training. Input raster layers are derived from digital terrain models, digital surface models, and intensity images from the IfSAR data. Results indicate about 15 percent of the study area is required to optimally train the ANN to extract hydrography when F1-scores for tested watersheds average between 66 and 68. Little benefit is gained by training beyond 15 percent of the study area. Fully connected hydrographic networks are generated for the U-net predictions using a novel approach that constrains a D-8 flow-routing approach to follow U-net predictions. This work demonstrates the ability of deep learning to derive surface water feature maps from complex terrain over a broad area.

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Zhang, Yizhong, Chunji Yin, Changxi Zheng, and Kun Zhou. "Computational hydrographic printing." ACM Transactions on Graphics 34, no. 4 (July 27, 2015): 1–11. http://dx.doi.org/10.1145/2766932.

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Sperrevik, A. K., K. H. Christensen, and J. Röhrs. "Observing and modeling currents on the continental slope: assimilation of high frequency radar currents and hydrography profiles." Ocean Science Discussions 11, no. 3 (June 4, 2014): 1357–90. http://dx.doi.org/10.5194/osd-11-1357-2014.

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Abstract. Assimilation of High Frequency (HF) radar current observations and CTD hydrography is performed with the 4D-Var analysis scheme implemented in the Regional Ocean Modeling System (ROMS). We consider both an idealized case, with a baroclinic slope current in a periodic channel, and a realistic case for the coast of Vesterålen in Northern Norway. In the realistic case the results of the data assimilation are compared with independent data from acoustic profilers and surface drifters. Best results are obtained when background error correlation scales are small (10 km or less) and when the data assimilation window is short, i.e. about one day. Furthermore, we find that the impact of assimilating HF radar currents is generally larger than the impact of CTD hydrography, which implies that the amount of hydrographic data is insufficient to constrain the solution. Combining the HF radar currents with a few hydrographic profiles gives significantly better results, which demonstrates the importance of complementing surface observations with observations of the vertical structure of the ocean.

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Sanz-Ramos, Marcos, Ernest Bladé, Fabián González-Escalona, Gonzalo Olivares, and José Luis Aragón-Hernández. "Interpreting the Manning Roughness Coefficient in Overland Flow Simulations with Coupled Hydrological-Hydraulic Distributed Models." Water 13, no. 23 (December 3, 2021): 3433. http://dx.doi.org/10.3390/w13233433.

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There is still little experience on the effect of the Manning roughness coefficient in coupled hydrological-hydraulic distributed models based on the solution of the Shallow Water Equations (SWE), where the Manning coefficient affects not only channel flow on the basin hydrographic network but also rainfall-runoff processes on the hillslopes. In this kind of model, roughness takes the role of the concentration time in classic conceptual or aggregated modelling methods, as is the case of the unit hydrograph method. Three different approaches were used to adjust the Manning roughness coefficient in order to fit the results with other methodologies or field observations—by comparing the resulting time of concentration with classic formulas, by comparing the runoff hydrographs obtained with aggregated models, and by comparing the runoff water volumes with observations. A wide dispersion of the roughness coefficients was observed to be generally much higher than the common values used in open channel flow hydraulics.

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Altić, Mirela. "From Coast to Coast: The Mapping of the Adriatic Sea by the Joint Forces of the Austro-Hungarian and Italian Hydrographic Offices." Abstracts of the ICA 1 (July 15, 2019): 1. http://dx.doi.org/10.5194/ica-abs-1-7-2019.

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Abstract. With the establishment of the second Austrian rule on the eastern Adriatic coast (1815), after several centuries, the Adriatic Sea was divided between two sides – Italian (Papal States and Kingdom of Two Sicilies) which ruled the western Adriatic coast, and the Austrian, which ruled the eastern coast and Lombardy-Venetia. Such division of the Adriatic Sea between the two powers in constant tension adversely affected the dynamics of mapping, and in the mid-19th century, there was a serious setback in mapping. In the 1860s, the strengthening of Italian and Austrian realms (Italy began its unification in 1860, and the Austrian Empire was converted into the Austro-Hungarian Monarchy in 1867) created a need for cooperation between the two empires on the joint mapping of the Adriatic Sea, which was to enable the production of modern charts based on a comprehensive survey covering the whole sea surface area, from coast to coast.For the purposes of the hydrographic survey, both imperial powers established their hydrographic offices as part of their military (naval) forces. The Austrian Empire established its Hydrographic Office in 1860, at first in Trieste and, from 1869 onwards, in the city of Pula (Hydrographisches Amt der k. u. k. Kriegsmarine). Its Italian counterpart, the Istituto idrografico della Marina, was founded in 1872 with its headquarters in Genoa (yet its first administrative act appeared as early as 1867). A systematic survey of the Adriatic Sea was started on its eastern side by the Austrian Hydrographic Office. It was conducted from 1866 to 1870 under the supervision of the experienced mariner and hydrographer Tobias Ritter von Oesterreicher. After land and sea surveys had been carried out on the basis of a dense triangulation network (first-, second-, and third-order triangulation), the first edition of the hydrographic charts of the eastern Adriatic coast was prepared by the Military Geographical Institute in Vienna and published by W. Essmann in Trieste as early as 1870 (and reissued in 1872). The survey resulted in a general chart of the Adriatic at a scale of 1:1 000 000, four course charts of the whole Adriatic Sea at a scale of 1:350 000, thirty-one coastal charts of the eastern Adriatic at scales of 1:40 000 to 1:100 000, and fifty-seven harbour charts at scales of 1:20 000 to 1:30 000. The survey of the Italian side of the Adriatic was conducted under the supervision of Counter-Admiral Duke Antonio Imbert, who earlier assisted Oesterreicher in the survey of the eastern coast. It started in 1867 and, by the end of 1873, conducted by the joint forces of the Austro-Hungarian and Italian hydrographic offices, resulted in a series of twenty-four charts at a scale of 1:100 000. Printed by the Military Geographical Institute in Vienna in 1873, together with a series covering the eastern Adriatic coast, these charts continued to serve as the main base map in the Office’s cartographic production for several decades, but also as a template for maps of Adriatic issued by foreign hydrographic offices, including that of the British Admiralty.The collaboration between the Austrian and Italian hydrographic offices continued, jointly promoting the improvement of quality of nautical charts of the Adriatic and the development of the hydrographic service in general. Apart from producing the first modern charts of the Adriatic, this survey marked the beginning of a state institutions for hydrographic exploration, including first measurements of geomagnetism, salinity, currents, and tides. The 19th-century charting thus played a crucial role in the birth of the official hydrographic services and the development of modern hydrographic exploration of the Adriatic. The proposed paper is based on archival sources.

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Lewicka, Oktawia, Mariusz Specht, Andrzej Stateczny, Cezary Specht, David Brčić, Alen Jugović, Szymon Widźgowski, and Marta Wiśniewska. "Analysis of GNSS, Hydroacoustic and Optoelectronic Data Integration Methods Used in Hydrography." Sensors 21, no. 23 (November 25, 2021): 7831. http://dx.doi.org/10.3390/s21237831.

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The integration of geospatial data in hydrography, performed using different measurement systems, involves combining several study results to provide a comprehensive analysis. Each of the hydroacoustic and optoelectronic systems is characterised by a different spatial reference system and the method for technical implementation of the measurement. Therefore, the integration of hydrographic data requires that problems in selected fields of electronics, geodesy and physics (acoustics and optics) be solved. The aim of this review is to present selected fusion methods applying the data derived from Global Navigation Satellite System (GNSS), Real Time Kinematic (RTK) measurements, hydrographic surveys, a photogrammetric pass using unmanned vehicles and Terrestrial Laser Scanning (TLS) and compare their accuracy. An additional goal is the evalution of data integration methods according to the International Hydrographic Organization (IHO) S-44 standard. The publication is supplemented by implementation examples of the integration of geospatial data in the Geographic Information System (GIS). The methods described indicate the lack of a uniform methodology for data fusion due to differences in both the spatial reference systems and the techniques used. However, the integration of hydroacoustic and optoelectronic data allows for high accuracy geospatial data to be obtained. This is confirmed by the methods cited, in which the accuracy of integrated geospatial data was in the order of several centimetres.

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Stanislawski, L. V., E. J. Shavers, A. J. Duffy, P. Thiem, N. Jaroenchai, S. Wang, Z. Jiang, B. J. Kronenfeld, and B. P. Buttenfield. "SCALING-UP DEEP LEARNING PREDICTIONS OF HYDROGRAPHY FROM IFSAR DATA IN ALASKA." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-4/W1-2022 (August 6, 2022): 449–56. http://dx.doi.org/10.5194/isprs-archives-xlviii-4-w1-2022-449-2022.

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Abstract. The United States National Hydrography Dataset (NHD) is a database of vector features representing the surface water features for the country. The NHD was originally compiled from hydrographic content on U.S. Geological Survey topographic maps but is being updated with higher quality feature representations through flow-routing techniques that derive hydrography from high-resolution elevation data. However, deriving hydrography through flow-routing methods is a complex process that needs to be tailored to different geographic conditions, which can lead to varying solutions. To address this problem, this paper evaluates automated deep learning and its transferability to extract hydrography from interferometric synthetic aperture radar (IfSAR) elevation data spanning a range of geographic conditions in Alaska.

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Saville, Jr., Thorndike, and Joseph M. Caldwell. "ACCURACY OF HYDROGRAPHIC SURVEYING IN AND NEAR THE SURF ZONE." Coastal Engineering Proceedings 1, no. 3 (January 1, 2000): 3. http://dx.doi.org/10.9753/icce.v3.3.

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The analysis and solution of most beach erosion problems are based to a significant degree on the quantitative changes in the bottom hydrography as observed in successive surveys. Critical decisions as to the dominant direction of littoral drift, the average rate of this drift, and the onshore-offshore movement of material are based largely on such hydrographic surveys. As the net changes between successive surveys are usually small compared to the area being studied, the degree of accuracy or comparability of the hydrographic surveys is of considerable importance. For instance, a net change of 100,000 cubic yards over one square mile of beach represents an average change in depth of only about 0.1 feet. Thus, it can be seen that uncompensated errors in depth measurement of as little as 0.1 feet can produce indications of significant littoral sand movement which might not exist in reality.

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Holzrichter, Michael, Bryan Johns, Delaine Thompson, and A. J. Boes. "Contouring of hydrographic data." Mathematical Modelling 7, no. 4 (1986): 547–60. http://dx.doi.org/10.1016/0270-0255(86)90033-3.

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Firsov, Yuriy Georgievich. "HYDROGRAPHIC INNOVATIVE EDUCATION METHODOLOGY." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 7, no. 1 (February 27, 2015): 123–29. http://dx.doi.org/10.21821/2309-5180-2015-7-1-123-129.

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Forget, Gaël, and Carl Wunsch. "Estimated Global Hydrographic Variability." Journal of Physical Oceanography 37, no. 8 (August 1, 2007): 1997–2008. http://dx.doi.org/10.1175/jpo3072.1.

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Abstract An estimate is made of the three-dimensional global oceanic temperature and salinity variability, omitting the seasonal cycle, both as a major descriptive element of the ocean circulation and for use in the error estimates of state estimation. Historical hydrography, recent data from the World Ocean Circulation Experiment, and Argo profile data are all used. Root-mean-square vertical displacements in the upper 300 m of the ocean are generally smaller than 50 m, except in energetic boundary currents and in the North Atlantic subpolar gyre. Variability in temperature and salinity is strongly correlated below the top 100 m. Salinity contributions to sea surface height variability appear more significant at low latitudes than expected, possibly resulting from advective and diffusive processes. Results are generally consistent with altimetric variability under two simple kinematic hypotheses, and much of the observed structure coincides with known dynamical features. A large fraction of the sea surface height variability is consistent with the hypothesis of dominance of the first baroclinic mode.

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Joyce, T. M. "The WOCE Hydrographic Program." Eos, Transactions American Geophysical Union 69, no. 5 (1988): 68. http://dx.doi.org/10.1029/88eo00050.

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Ivanovic, Radomir, Marko Ivanovic, and Mrdjan Djokic. "Hydrographic resources of Ibarski Kolasin in the function of tourism development." Glasnik Srpskog geografskog drustva 91, no. 1 (2011): 117–34. http://dx.doi.org/10.2298/gsgd1101117i.

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Hydrographic objects (hydrograph) of a territory may be an important natural potential for tourism development. Ibarski Kolasin is a territory in northern Kosovo. Very poor in economic terms. Development of tourism activities in this area, it could be a significant source of income. Accumulation Gazivode is remarkably fit into the landscape, and together with the surrounding mountains, Mokra Gora and Rogozna, represents a specific geographical areas, which could be excellent tourist realized.

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Boudani, Mustapha Rabie, Mohamed Mazour, Hichem Mazighi, and Omar Djoukbala. "Development of a minimalist conceptual numerical model for flood forecasting and management under GIS environment." Journal of Water and Climate Change 11, S1 (April 15, 2020): 359–86. http://dx.doi.org/10.2166/wcc.2020.265.

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Abstract The floods that Algeria has experienced in recent years are among the most significant natural disasters recorded by the country. These disasters, whose amplitude and frequency have tended to become increasingly irregular in space and time, in the current context of global climate change, encourage us to improve our flood management and forecasting strategies, notably through the re-evaluation of protection structure capacities, designed on the basis of hydrological data analyzed by statistical adjustment of past rainfall hazards. The objective of this study is to develop a minimalist conceptual numerical model for flood forecasting and management under GIS environment for the north-east region of Algeria. This model was developed by analyzing hydrographic data that can be adapted to climate data collected in real time, to predict short-term flood hydrographs in all segments of the hydrographic network, based on the Sokolovsky model for construction of synthetic hydrographs, combined with the Horton architecture for basin discretization. We obtained accuracy on past rainfall hazard simulations around 65.2% for peak flow amplitudes and 88.3% for surface runoff base times. This low-cost simple model opens the way to more possibilities in flood management, and can be improved through better spatialization and calibration with more field data.

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Duan, Jing, Xiaoxia Wan, and Jianan Luo. "Research on the hydrographic survey cycle for updating navigational charts." Journal of Navigation 74, no. 4 (January 21, 2021): 750–62. http://dx.doi.org/10.1017/s0373463320000776.

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AbstractDue to the vast ocean area and limited human and material resources, hydrographic survey must be carried out in a selective and well-planned way. Therefore, scientific planning of hydrographic surveys to ensure the effectiveness of navigational charts has become an urgent issue to be addressed by the hydrographic office of each coastal state. In this study, a reasonable calculation model of hydrographic survey cycle is established, which can be used to make the plan of navigational chart updating. The paper takes 493 navigational charts of Chinese coastal ports and fairways as the research object, analyses the fundamental factors affecting the hydrographic survey cycle and gives them weights, proposes to use the BP neural network to construct the relationship between the cycle and the impact factors, and finally establishes a calculation model of the hydrographic survey cycle. It has been verified that the calculation cycle of the model is effective, and it can provide reference for hydrographic survey planning and chart updating, as well as suggestions for navigation safety.

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Elsobeiey, M. "PERFORMANCE ANALYSIS OF LOW-COST SINGLE-FREQUENCY GPS RECEIVERS IN HYDROGRAPHIC SURVEYING." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W5 (October 5, 2017): 67–71. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w5-67-2017.

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The International Hydrographic Organization (IHO) has issued standards that provide the minimum requirements for different types of hydrographic surveys execution to collect data to be used to compile navigational charts. Such standards are usually updated from time to time to reflect new survey techniques and practices and must be achieved to assure both surface navigation safety and marine environment protection. Hydrographic surveys can be classified to four orders namely, special order, order 1a, order 1b, and order 2. The order of hydrographic surveys to use should be determined in accordance with the importance to the safety of navigation in the surveyed area. Typically, geodetic-grade dual-frequency GPS receivers are utilized for position determination during data collection in hydrographic surveys. However, with the evolution of high-sensitivity low-cost single-frequency receivers, it is very important to evaluate the performance of such receivers. This paper investigates the performance of low-cost single-frequency GPS receivers in hydrographic surveying applications. The main objective is to examine whether low-cost single-frequency receivers fulfil the IHO standards for hydrographic surveys. It is shown that the low-cost single-frequency receivers meet the IHO horizontal accuracy for all hydrographic surveys orders at any depth. However, the single-frequency receivers meet only order 2 requirements for vertical accuracy at depth more than or equal 100&thinsp;m.

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da Silva Brito, Maiara Tábatha, Leidiane Pereira Diniz, Ully M. Pozzobom, Victor Lemes Landeiro, and Francisco Diogo R. Sousa. "Cladocera (Crustacea: Branchiopoda) from the state of Mato Grosso, Brazil." Annales de Limnologie - International Journal of Limnology 56 (2020): 7. http://dx.doi.org/10.1051/limn/2020005.

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Studies on Cladocera biodiversity in Brazilian freshwater ecosystems are intensifying. However, the fauna of some hydrographic regions is still poorly known. We investigated the richness and species composition of cladocerans in lakes of the Pantanal from the state of Mato Grosso (Paraguay hydrographic region), Brazil. In addition, we cataloged the known cladoceran species in each hydrographic region of the state. Occurrence data were obtained from the literature and samples collected from 50 lakes in the northern Pantanal. We recorded 120 cladoceran species from eight families in the state of Mato Grosso. The occurrence of these species was recorded in the Amazon and Paraguay hydrographic regions. We are unaware of studies on cladocerans conducted in the Tocantins-Araguaia hydrographic region. We reported 17 new records in the Pantanal samples (Paraguay hydrographic region). Overall, richness estimates reveal that 72.6% of the state's cladoceran fauna is already known, while for the Paraguay hydrographic region this estimate is 72.2%. In general, the cladocerans from the Amazon and Paraguay regions did not differ. Our findings allow us to infer the need for further studies in the different hydrographic regions found in Mato Grosso in order to improve the knowledge of cladoceran biodiversity. We suggest a greater sampling effort, particularly in the littoral zone of aquatic ecosystems in this state, which can harbor great biodiversity.

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Masetti, Giuseppe, Tyanne Faulkes, Matthew Wilson, and Julia Wallace. "Effective Automated Procedures for Hydrographic Data Review." Geomatics 2, no. 3 (August 25, 2022): 338–54. http://dx.doi.org/10.3390/geomatics2030019.

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Reviewing hydrographic data for nautical charting is still a predominately manual process, performed by experienced analysts and based on directives developed over the years by the hydrographic office of interest. With the primary intent to increase the effectiveness of the review process, a set of automated procedures has been developed over the past few years, translating a significant portion of the NOAA Office of Coast Survey’s specifications for hydrographic data review into code (i.e., the HydrOffice applications called QC Tools and CA Tools). When applied to a large number of hydrographic surveys, it has been confirmed that such procedures improve both the quality and timeliness of the review process. Increased confidence in the reviewed data, especially by personnel in training, has also been observed. As such, the combined effect of applying these procedures is a novel holistic approach to hydrographic data review. Given the similarities of review procedures among hydrographic offices, the described approach has generated interest in the ocean mapping community.

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Köster, Friedrich W., Christian Möllmann, Hans-Harald Hinrichsen, Kai Wieland, Jonna Tomkiewicz, Gerd Kraus, Rüdiger Voss, et al. "Baltic cod recruitment – the impact of climate variability on key processes." ICES Journal of Marine Science 62, no. 7 (January 1, 2005): 1408–25. http://dx.doi.org/10.1016/j.icesjms.2005.05.004.

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Abstract Large-scale climatic conditions prevailing over the central Baltic Sea resulted in declining salinity and oxygen concentrations in spawning areas of the eastern Baltic cod stock. These changes in hydrography reduced the reproductive success and, combined with high fishing pressure, caused a decline of the stock to the lowest level on record in the early 1990s. The present study aims at disentangling the interactions between reproductive effort and hydrographic forcing leading to variable recruitment. Based on identified key processes, stock dynamics is explained using updated environmental and life stage-specific abundance and production time-series. Declining salinities and oxygen concentrations caused high egg mortalities and indirectly increased egg predation by clupeid fish. Low recruitment, despite enhanced hydrographic conditions for egg survival in the mid-1990s, was due to food limitation for larvae, caused by the decline in the abundance of the copepod Pseudocalanus sp. The case of the eastern Baltic cod stock exemplifies the multitude effects climatic variability may have on a fish stock and underscores the importance of knowledge of these processes for understanding stock dynamics.

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Silva, Márcio Santos, Cristiane Kreutz, Robertson Fonseca de Azevedo, and Maristela Denise Moresco Mezzomo. "Creation of an environmental protection area in a public supply source: possibilities and challenges in Cianorte - Paraná." Revista Engenharia na Agricultura - Reveng 29 (December 8, 2021): 389–404. http://dx.doi.org/10.13083/reveng.v29i1.12621.

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This work analyzed the contribution that the creation of Environmental Protection Areas (EPA) may bring to the conservation of hydrographic basins used as public water sources. The object of study of this work was the hydrographic basin of the Ligeiro River which, by 2022 onwards, will be the new source of public supply in the city of Cianorte-Paraná, replacing the hydrographic basin of the Bolívar stream. The latter has environmental impacts caused mainly by the expansion of urban areas and inadequate practice of land use, occupation, and management, which affects the population’s supply, particularly on days with high levels of rainfall. The study area involved the creation of two municipal EPAs in the hydrographic basin of the Ligeiro River, located in the municipalities of Araruna and Cianorte, with areas of 209.76 km² and 219.82 km², respectively. It is believed that the creation of Environmental Protection Areas in the Ligeiro River hydrographic basin will also present challenges, but it will enable the conservation of natural resources and, especially, of water resources, given the quality of the water. It is expected that these actions will help to minimize or even prevent, in the future, the Ligeiro river hydrographic basin from being as or more impacted as the Bolivar stream basin.

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MacMahan, Jamie. "Hydrographic Surveying from Personal Watercraft." Journal of Surveying Engineering 127, no. 1 (February 2001): 12–24. http://dx.doi.org/10.1061/(asce)0733-9453(2001)127:1(12).

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31

Toole, John, and Bruce Warren. "A Trans-Indian Hydrographic Section." Eos, Transactions American Geophysical Union 67, no. 44 (1986): 838. http://dx.doi.org/10.1029/eo067i044p00838.

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Drummond, Scott E. "News—certification of hydrographic surveyors." Marine Geodesy 9, no. 3 (January 1985): 381–84. http://dx.doi.org/10.1080/15210608509379534.

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Pasquay, J. N. "Hydrographic Requirements for Modern Shipping." Journal of Navigation 39, no. 3 (September 1986): 341–48. http://dx.doi.org/10.1017/s0373463300000813.

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Until 1950 the largest ships of the merchant fleet and the major warships had the same draught, about 12 m. Hydrographic offices concentrated their efforts on those areas likely to contain hazards to such vessels, that is to say the areas extending from the shallow waters to the 20 m contour line. The maximum draught of warships has been stable whereas the draught of merchant vessels increased considerably up to 30 m in recent years. A VLCC may risk grounding after having crossed the 30 m line or even the 40 m line. Nowadays, the part of the continental shelf which is best known is the part in which the largest vessels are unable to operate.

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Davies, Andrew, Mark Kinoshita, Richard Van de Water, and G. F. D. Duff. "Spline analysis of Hydrographic data." Mathematical Modelling 7, no. 4 (1986): 585–93. http://dx.doi.org/10.1016/0270-0255(86)90036-9.

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Bunyon, D. "The United Kingdom Hydrographic Office." Cartographic Journal 28, no. 1 (June 1991): 6–9. http://dx.doi.org/10.1179/caj.1991.28.1.6.

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Tan, Bin, Zheng Liu, and Bo Li. "A Marine Hydrographic Measurement System." Journal of Physics: Conference Series 1578 (July 2020): 012221. http://dx.doi.org/10.1088/1742-6596/1578/1/012221.

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Brockmann, Carsten W., and Joachim W. Dippner. "Tidal correction of hydrographic measurements." Deutsche Hydrographische Zeitschrift 40, no. 6 (November 1987): 241–60. http://dx.doi.org/10.1007/bf02226279.

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Barford, Megan. "D.176: Sextants, numbers, and the Hydrographic Office of the Admiralty." History of Science 55, no. 4 (July 5, 2017): 431–56. http://dx.doi.org/10.1177/0073275317712817.

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In the 1830s and 1840s, the Hydrographic Office of the British Admiralty developed and oversaw one of the major state-run surveying projects of the nineteenth century. This involved a range of instruments whose circulation was increasingly regulated. Using extant museum collections and the correspondence of those involved, this article explores how such objects can be used to discuss both bureaucratic organization at a time of expanding government and the complex issues of sociability involved in hydrographic surveying. Surveying officers worked in a context in which the propriety of property on public service was a pervasive question. Instruments might be given as gifts between officers, appropriated as recompense, absorbed as state property, and disputed between friends. The ownership, provision, and treatment of instruments in particular could be used to demonstrate an officer’s peculiar zeal or institutional neglect. To those outside the ship, what was understood as over-instrumentation became amusing spectacle. On board, their use was part of a deeply hierarchical order of work in regions of colonial and mercantile importance. In examining the relationships around these instruments of survey, the paper proposes a richer understanding of the material culture of hydrography in the early nineteenth century.

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Amatulli, Giuseppe, Jaime Garcia Marquez, Tushar Sethi, Jens Kiesel, Afroditi Grigoropoulou, Maria M. Üblacker, Longzhu Q. Shen, and Sami Domisch. "Hydrography90m: a new high-resolution global hydrographic dataset." Earth System Science Data 14, no. 10 (October 17, 2022): 4525–50. http://dx.doi.org/10.5194/essd-14-4525-2022.

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Abstract. The geographic distribution of streams and rivers drives a multitude of patterns and processes in hydrology, geomorphology, geography, and ecology. Therefore, a hydrographic network that accurately delineates both small streams and large rivers, along with their topographic and topological properties, with equal precision would be indispensable in the earth sciences. Currently, available global hydrographies do not feature small headwater streams in great detail. However, these headwaters are vital because they are estimated to contribute to more than 70 % of overall stream length. We aimed to fill this gap by using the MERIT Hydro digital elevation model at 3 arcsec (∼90 m at the Equator) to derive a globally seamless, standardised hydrographic network, the “Hydrography90m”, with corresponding stream topographic and topological information. A central feature of the network is the minimal upstream contributing area, i.e. flow accumulation, of 0.05 km2 (or 5 ha) to initiate a stream channel, which allowed us to extract headwater stream channels in great detail. By employing a suite of GRASS GIS hydrological modules, we calculated the range-wide upstream flow accumulation and flow direction to delineate a total of 1.6 million drainage basins and extracted globally a total of 726 million unique stream segments with their corresponding sub-catchments. In addition, we computed stream topographic variables comprising stream slope, gradient, length, and curvature attributes as well as stream topological variables to allow for network routing and various stream order classifications. We validated the spatial accuracy and flow accumulation of Hydrography90m against NHDPlus HR, an independent, national high-resolution hydrographic network dataset of the United States. Our validation shows that the newly developed Hydrography90m has the highest spatial precision and contains more headwater stream channels compared to three other global hydrographic datasets. This comprehensive approach provides a vital and long-overdue baseline for assessing actual streamflow in headwaters and opens new research avenues for high-resolution studies of surface water worldwide. Hydrography90m thus offers significant potential to facilitate the assessment of freshwater quantity and quality, inundation risk, biodiversity, conservation, and resource management objectives in a globally comprehensive and standardised manner. The Hydrography90m layers are available at https://doi.org/10.18728/igb-fred-762.1 (Amatulli et al., 2022a), and while they can be used directly in standard GIS applications, we recommend the seamless integration with hydrological modules in open-source QGIS and GRASS GIS software to further customise the data and derive optimal utility from it.

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Tang, Chi Hung, Chong Kim Wong, Alle An Ying Lie, and Ying Kit Yung. "Size structure and pigment composition of phytoplankton communities in different hydrographic zones in Hong Kong's coastal seas." Journal of the Marine Biological Association of the United Kingdom 95, no. 5 (March 17, 2015): 885–96. http://dx.doi.org/10.1017/s0025315415000223.

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The abundance and community composition of phytoplankton are influenced by a suite of interacting environmental factors. Hong Kong's marine environment features a hydrographic gradient from an estuarine zone in the west to a transition zone in the middle and an oceanic zone in the east. Size fractionation combined with high performance liquid chromatography (HPLC) pigment analyses were used to investigate the phytoplankton communities in different hydrographic zones during summer (July–August 2009) and winter (December 2009–January 2010). Clear temporal and spatial variations in environmental parameters occurred among hydrographic zones. Results of principal component analysis (PCA) revealed that the major deviating factors among hydrographic zones were turbidity and salinity in summer and nitrate and phosphate in winter. Phytoplankton abundance showed significant temporal variations, but no zonal variations. Phytoplankton communities in all hydrographic zones were dominated by cells >5 µm in both summer and winter. Chlorophyll a concentrations for most size fractions correlated significantly with temperature. The high concentration of fucoxanthin indicated that the phytoplankton community was dominated by diatoms in both summer and winter, while dinoflagellates, cryptophytes, cyanobacteria and other minor groups occurred sporadically in low abundance. The spatial pattern of phytoplankton in Hong Kong's coastal seas did not reflect the hydrographic zonation, but the phytoplankton in the semi-enclosed Tolo Harbour and Deep Bay were different from those in the other zones.

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Specht, Mariusz, Andrzej Stateczny, Cezary Specht, Szymon Widźgowski, Oktawia Lewicka, and Marta Wiśniewska. "Concept of an Innovative Autonomous Unmanned System for Bathymetric Monitoring of Shallow Waterbodies (INNOBAT System)." Energies 14, no. 17 (August 29, 2021): 5370. http://dx.doi.org/10.3390/en14175370.

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Bathymetry is a subset of hydrography, aimed at measuring the depth of waterbodies and waterways. Measurements are taken inter alia to detect natural obstacles or other navigational obstacles that endanger the safety of navigation, to examine the navigability conditions, anchorages, waterways and other commercial waterbodies, and to determine the parameters of the safe depth of waterbodies in the vicinity of ports, etc. Therefore, it is necessary to produce precise and reliable seabed maps, so that any hazards that may occur, particularly in shallow waterbodies, can be prevented, including the high dynamics of hydromorphological changes. This publication is aimed at developing a concept of an innovative autonomous unmanned system for bathymetric monitoring of shallow waterbodies. A bathymetric and topographic system will use autonomous unmanned aerial and surface vehicles to study the seabed relief in the littoral zone (even at depths of less than 1 m), in line with the requirements set out for the most stringent International Hydrographic Organization (IHO) order—exclusive. Unlike other existing solutions, the INNOBAT system will enable the coverage of the entire surveyed area with measurements, which will allow a comprehensive assessment of the hydrographic and navigation situation in the waterbody to be conducted.

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Fernández de Puelles, Maria Luz, and Juan Carlos Molinero. "Decadal changes in hydrographic and ecological time-series in the Balearic Sea (western Mediterranean), identifying links between climate and zooplankton." ICES Journal of Marine Science 65, no. 3 (February 28, 2008): 311–17. http://dx.doi.org/10.1093/icesjms/fsn017.

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Abstract Fernández de Puelles, M. L., and Molinero, J. C. 2008. Decadal changes in hydrographic and ecological time-series in the Balearic Sea (western Mediterranean), identifying links between climate and zooplankton. – ICES Journal of Marine Science, 65: 311–317. We investigated possible relationships between climate, hydrography, and zooplankton abundance in the Balearic Sea (BS), during a 10-year survey period spanning January 1994 to December 2003. It was demonstrated that large-scale atmospheric variability in the North Atlantic (NA) Ocean acts as a driver of regional meteorological variations and hydrographic patterns in the BS. The results also revealed that the variability of copepods, appendicularians, cladocerans, siphonophores, doliolids, and ostracods is closely related to variations in water temperature recorded during strong anomalies of the NA climate (>1 s.d.). Although the time-series that we analysed cover a period that is relatively short for investigating climate effects on marine ecosystems, the statistical results reported were consistent enough to emphasize the NA’s climate effect on the BS. The cascade of links identified by these results should be considered and integrated into the assessment and modelling studies of pelagic ecosystem and biogeochemical fluxes in the western Mediterranean Sea.

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LeGrand, P., H. Mercier, and T. Reynaud. "Combining T/P altimetric data with hydrographic data to estimate the mean dynamic topography of the North Atlantic and improve the geoid." Annales Geophysicae 16, no. 5 (May 31, 1998): 638–50. http://dx.doi.org/10.1007/s00585-998-0638-0.

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Abstract. The mean dynamic topography of the surface of the North Atlantic is estimated using an inverse model of the ocean circulation constrained by hydrographic and altimetric observations. In the North Atlantic, altimetric observations have no significant impact on the topography estimate because of the limited precision of available geoid height models. They have a significant impact, however, when uncertainties in the density field are increased to simulate interpolation errors in regions where hydrographic data are scarce. This result, which moderates the conclusion drawn by Ganachaud and co-workers of no significant contribution of altimetric observations to the determination of the large-scale steady circulation, reflects the simple idea that altimetric data are most useful near the surface of the ocean and in areas where the hydrography is poorly determined. One application of the present inverse estimate of the mean dynamic topography is to compute a geoid height correction over the North Atlantic which reduces the uncertainty in the geoid height expanded to spherical harmonic 40 down to a level of about 5 cm.Key words. Oceanography: general (climate and interannual variability) · Oceanography: physical (general circulation; remote sensing)

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Fernández de Puelles, M. Luz, Joaquín Valencia, Javier Jansá, and Ana Morillas. "Hydrographical characteristics and zooplankton distribution in the Mallorca channel (Western Mediterranean): spring 2001." ICES Journal of Marine Science 61, no. 4 (January 1, 2004): 654–66. http://dx.doi.org/10.1016/j.icesjms.2004.03.031.

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Abstract The distribution of zooplankton in the upper 100 m of the Mallorca channel (Balearic Sea) was investigated during the spring of 2001 and related to the main hydrographic parameters. Synoptic satellite images were examined and 29 stations were sampled by means of oblique hauls. The sea surface temperature, salinity, and chlorophyll a in the channel show the existence of a hydrological front related to the composition of phyto- and zooplankton. The main zooplankton groups revealed a horizontal distribution pattern related to the hydrographic features of the area. The highest zooplankton abundance, mainly due to copepods (78% of the total zooplankton), was found where the coolest and more saline waters were observed, i.e. in the northern part of the channel. The lowest abundance, mainly represented by siphonophores, chaetognaths, and doliolids, was in the south in the warmer and less saline waters, indicating the input of Atlantic waters into the channel. The spatial distribution of the main species and zooplankton groups was also examined in relation to the frontal system, suggesting their function as biological indicators of the upper water hydrography in the Balearic Sea (Western Mediterranean).

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Bisantino, Tiziana, Vincenzo Pizzo, Maurizio Polemio, and Francesco Gentile. "Analysis of the flooding event of October 22-23, 2005 in a small basin in the province of Bari (Southern Italy)." Journal of Agricultural Engineering 47, no. 4 (December 15, 2016): 197. http://dx.doi.org/10.4081/jae.2016.531.

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In the province of Bari the hydrographic network consists of ephemeral streams called lame. In these watercourses the absence of runoff for long periods contributed to unfounded beliefs concerning the hydraulic safety of the landscape and therefore uncontrolled changes in streambeds and floodplains. In these streams high water discharges can occur during heavy rainfalls, as demonstrated by the floods that hit the city of Bari in the late nineteenth and early twentieth century. The flooding event of October 22-23, 2005 can be considered catastrophic as it resulted in six deaths, numerous injuries and substantial damage sustained by road and railway infrastructures at the intersection with the hydrographic network. This study aims to analyse the severity of the event in terms of the response of the landscape with reference to the case of the lama Scappagrano basin, where a Eurostar train derailed due to the collapse of the railway embankment. Coupled hydrological and two-dimensional hydraulic modelling was performed to reconstruct the flood hydrograph and water depths on the upstream side of the embankment. The results were used to set the boundary conditions to analyse the internal stability of the embankment using a finite element method.

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Stateczny, Andrzej, Cezary Specht, Mariusz Specht, David Brčić, Alen Jugović, Szymon Widźgowski, Marta Wiśniewska, and Oktawia Lewicka. "Study on the Positioning Accuracy of GNSS/INS Systems Supported by DGPS and RTK Receivers for Hydrographic Surveys." Energies 14, no. 21 (November 7, 2021): 7413. http://dx.doi.org/10.3390/en14217413.

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Hydrographic surveys, in accordance with the International Hydrographic Organization (IHO) S-44 standard, can be carried out in the following five orders: Exclusive, Special, 1a, 1b and 2, for which minimum accuracy requirements for the applied positioning system have been set out. They are as follows, respectively: 1, 2, 5, 5 and 20 m, with a confidence level of 95% in two-dimensional space. The Global Navigation Satellite System (GNSS) network solutions (accuracy: 2–3 cm (p = 0.95)) and the Differential Global Positioning System (DGPS) (accuracy: 1–2 m (p = 0.95)) are now commonly used positioning methods in hydrography. Due to the fact that a new order of hydrographic surveys has appeared in the IHO S-44 standard from 2020—Exclusive, looking at the current positioning accuracy of the DGPS system, it is not known whether it can be used in it. The aim of this article is to determine the usefulness of GNSS/Inertial Navigation Systems (INS) for hydrographic surveys. During the research, the following two INSs were used: Ekinox2-U and Ellipse-D by the SBG Systems, which were supported by DGPS and Real Time Kinematic (RTK) receivers. GNSS/INS measurements were carried out during the manoeuvring of the Autonomous/Unmanned Surface Vehicle (ASV/USV) named “HydroDron” on Kłodno lake in Zawory. The acquired data were processed using the mathematical model that allows us to assess whether any positioning system at a given point in time meets (or not) the accuracy requirements for each IHO order. The model was verified taking into account the historical and current test results of the DGPS and RTK systems. Tests have confirmed that the RTK system meets the requirements of all the IHO orders, even in situations where it is not functioning 100% properly. Moreover, it was proven that the DGPS system does not only meet the requirements provided for the most stringent IHO order, i.e., the Exclusive Order (horizontal position error ≤ 1 m (p = 0.95)). Statistical analyses showed that it was only a few centimetres away from meeting this criterion. Therefore, it can be expected that soon it will be used in all the IHO orders.

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Barford, Megan. "Fugitive Hydrography: The Nautical Magazine and the Hydrographic Office of the Admiralty, c.1832–1850." International Journal of Maritime History 27, no. 2 (May 2015): 208–26. http://dx.doi.org/10.1177/0843871415571038.

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Specht. "Method of Evaluating the Positioning System Capability for Complying with the Minimum Accuracy Requirements for the International Hydrographic Organization Orders." Sensors 19, no. 18 (September 6, 2019): 3860. http://dx.doi.org/10.3390/s19183860.

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According to the IHO (International Hydrographic Organization) S-44 standard, hydrographic surveys can be carried out in four categories, the so-called orders—special, 1a, 1b, and 2—for which minimum accuracy requirements for the applied positioning system have been set out. These amount to, respectively: 2 m, 5 m, 5 m, and 20 m at a confidence level of 0.95. It is widely assumed that GNSS (Global Navigation Satellite System) network solutions with an accuracy of 2–5 cm (p = 0.95) and maritime DGPS (Differential Global Positioning System) systems with an error of 1–2 m (p = 0.95) are currently the two main positioning methods in hydrography. Other positioning systems whose positioning accuracy increases from year to year (and which may serve as alternative solutions) have been omitted. The article proposes a method that enables an assessment of any given navigation positioning system in terms of its compliance (or non-compliance) with the minimum accuracy requirements specified for hydrographic surveys. The method concerned clearly assesses whether a particular positioning system meets the accuracy requirements set out for a particular IHO order. The model was verified, taking into account both past and present research results (stationary and dynamic) derived from tests on the following systems: DGPS, EGNOS (European Geostationary Navigation Overlay Service), and multi-GNSS receivers (GPS/GLONASS/BDS/Galileo). The study confirmed that the DGPS system meets the requirements for all IHO orders and proved that the EGNOS system can currently be applied in measurements in the orders 1a, 1b, and 2. On the other hand, multi-GNSS receivers meet the requirements for order 2, while some of them meet the requirements for orders 1a and 1b as well.

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Atkinson, C. P., H. L. Bryden, S. A. Cunningham, and B. A. King. "Atlantic transport variability at 25° N in six hydrographic sections." Ocean Science 8, no. 4 (July 19, 2012): 497–523. http://dx.doi.org/10.5194/os-8-497-2012.

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Abstract. In January and February 2010, a sixth transatlantic hydrographic section was completed across 25° N, extending the hydrographic record at this latitude to over half a century. In combination with continuous transport measurements made since 2004 at 26.5° N by the Rapid-WATCH project, we reassess transport variability in the 25° N hydrographic record. Past studies of transport variability at this latitude have assumed transport estimates from each hydrographic section to represent annual average conditions. In this study the uncertainty in this assumption is assessed through use of Rapid-WATCH observations to quantify sub-seasonal and seasonal transport variability. Whilst in the upper-ocean no significant interannual or decadal transport variability are identified in the hydrographic record, in the deep ocean transport variability in both depth and potential temperature classes suggests some interannual or decadal variability may have occurred. This is particularly striking in the lower North Atlantic Deep Water where southward transports prior to 1998 were greater than recent transports by several Sverdrups. Whilst a cooling and freshening of Denmark Straits Overflow Water has occurred which is coincident with these transport changes, these water mass changes appear to be density compensated. Transport changes are the result of changing velocity shear in the vicinity of the Deep Western Boundary Current.

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Atkinson, C. P., H. L. Bryden, S. A. Cunningham, and B. A. King. "Atlantic transport variability at 25° N in six hydrographic sections." Ocean Science Discussions 9, no. 1 (January 16, 2012): 105–62. http://dx.doi.org/10.5194/osd-9-105-2012.

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Abstract. In January and February 2010, a sixth transatlantic hydrographic section was completed across 25° N, extending the hydrographic record at this latitude to over half a century. In combination with continuous transport measurements made since 2004 at 26° N by the Rapid-WATCH project, we reassess transport variability in the 25° N hydrographic record. Past studies of transport variability at this latitude have assumed transport estimates from each hydrographic section to represent annual average conditions. In this study the uncertainty in this assumption is assessed through use of Rapid-WATCH observations to quantify sub-seasonal and seasonal transport variability. Whilst in the upper-ocean no significant interannual or decadal transport variability are identified in the hydrographic record, in the deep ocean transport variability in both depth and potential temperature classes suggests some interannual or decadal variability may have occurred. This is particularly striking in the lower North Atlantic Deep Water where southward transports prior to the 1990s were higher than recent transports by several Sverdrups. Whilst a cooling and freshening of Denmark Straits Overflow Water has occurred which is coincident with these transport changes, these water mass changes appear to be density compensated. Transport changes are the result of changing velocity shear in the vicinity of the Deep Western Boundary Current.

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Journal articles on the topic 'Hydrographic'

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