Nautical Charts Research Articles

From Coast to Coast: The Mapping of the Adriatic Sea by the Joint Forces of the Austro-Hungarian and Italian Hydrographic Offices

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.

NOAA’s Certification program in Marine Cartography

Abstract. Since its establishment in 1807, the National Oceanic and Atmospheric Administration’s (NOAA) Office of Coast Survey has provided nautical charts to support safe shipping, national defence, and the delamination of maritime boundaries. The mission of the office is to provide navigation products and services that ensure safe and efficient maritime commerce on America’s oceans and coastal waters, and in the Great Lakes. The Office of Coast Survey employs cartographers, hydrographers, physical scientists, managers and administrative staff in order to fulfil its mission. Until recently, training in nautical cartography at the office of Coast Survey was conducted at the branch level and differed based on level of employee seniority (i.e., Entry, Intermediate and Advanced) and the processing branch of the employee. Over the past two years, NOAA has established a Coast Survey CAT B program that is intended to train and educate to up to 13 cartographers per year in nautical cartography, through a combination of lectures, hands-on chart production experience, details to various branches within the Coast Survey, and field trips to working hydrographic survey vessels through six training modules spread over a one-year period, spread over six courses that include:Refresher course that provides a review of the basic math, computer and communication technology, marine geography, hydrography, and geodetic topics. The goal of this course is to ensure that students have a sufficient academic background to succeed in the subsequent CAT-B program courses and other activities.Introduction to Cartography course that reviews elements of cartography, specifically scale, design, and data manipulation techniques. Students will gain an appreciation for maps and map-making, including manual techniques. This introductory course will include hands-on use of computer graphics tools.Map Design course that reviews the various styles and techniques associated with cartographic design. The course will require the student to: 1) analyse chart design parameters, 2) compile thematic cartographic projects, and 3) experiment with map design.GIS and Spatial Analysis course that provides students with a comprehensive understanding of spatial analysis methods and they will learn practical skills in using GIS and spatial analysis. The class covers the methods of spatial analysis including measuring aspects of geometric features and identifying spatial patterns of geospatial objects that are represented as point, line, network, areal data, and 3-D surfaces.GIS and Spatial Modelling course that provides the students a foundation and understanding of various issues related to modelling and simulation in the GIS. It will address the concepts, tools, and techniques of GIS modelling (vector- and raster-based modelling). In addition, it will present modelling concepts and theory as well as provide opportunities for hands-on model design, construction, and application.NOAA training project and internship program course that includes: 1) a detailed review of many of the activities conducted by the branches in NOAA’s Marine Chart Division and 2) a training project that demonstrates the student’s ability to implement the knowledge gained during the certification.This paper presents a newly established CAT B certificate program in Standards of Competence for Nautical Cartographers that is conducted at NOAA’s main campus in Silver Spring, Maryland, USA. The CAT B certificate program provides NOAA a mechanism to both enhance building capacity within the organization and recognizing NOAA cartographers for their capabilities and efforts. In addition, such a program at NOAA can also be used to recruit new employees and help to build capacity in sister organizations.

The Re-Scheme Project for the Mexican Cartography Plan

Abstract. The Mexican Navy is empowered by its current federal legislation to produce charts over military and civilian ports within Mexico. To fulfil this task, a National Nautical Cartography Program has been developed. The program currently consists on a production and maintenance scheme of 254 nautical charts at scale within general, coastal, approach, harbour and berthing usage bands. The design of the National Nautical Cartography Program is the result of port infrastructure and maritime traffic analysis that also follows the International Hydrographic Organization (IHO) recommendations published in the “Regulations for International (INT) Charts and Chart Specifications of the IHO” S-4. This paper will present details on the re-scheme project that includes Electronic Navigation Chart (ENC) cell footprints and their compilation scales in order to produce a seamless chart coverage along the coastlines of Mexico and a more efficient production workflow. The re-scheme project intends to provide more detail to existing charts and also provide current updates to ever-changing port infrastructure of the country and the emergence of new navigation routes for commerce and tourism. Additional benefits of the re-scheme project include: Providing an orderly design of ENC cell for program management, standardizing progressive scales with chart display, and establishing better international collaboration between Mexico and its neighbours on charts along the borders and INT charts.

Towards automated validation of charted soundings: Existing tests and limitations

ABSTRACT The nautical chart is one of the fundamental tools in navigation used by mariners to plan and safely execute voyages. Its compilation follows strict cartographic constraints with the most prominent being that of the safety. Thereby, the cartographer is called to make the selection of the bathymetric information for portrayal on charts in a way that, at any location, the expected water depth is not deeper than the source information. To validate the shoal-biased pattern of selection two standard tests are used, i.e. the triangle and edge tests. To date, some efforts have been made towards the automation of the triangle test, but the edge test has been largely ignored. In the context of research on a fully automated solution for the compilation of charts at different scales from the source information, this paper presents an algorithmic implementation of the two tests for the validation of selected soundings. Through a case study with real-world data, it presents the improved performance of the implementation near and within depth curves and coastlines and points out the importance of the edge test in the validation process. It also presents the, by definition, intrinsic limitation of the two tests as part of a fully automated solution and discusses the need for a new test that will complement or supersede the existing ones.

Navigational, Historical and Environmental Perspective of St. Augustine Waterways

St. Augustine, the oldest city in North America, lies at Mile 778 of the Atlantic Intracoastal Waterway, which runs 1095 miles from Norfolk, Virginia, to Miami, Florida. This guide is designed to help boaters enjoy and appreciate the natural and cultural resources accessible from recreational vessels in the St. Augustine area. The maps and text display and describe features from the maritime history of St. Augustine; resources important to boaters and anglers, including marinas, waterfront restaurants, and boat ramps; representative fish and wildlife; the distribution of natural resources, such as salt marshes, estuaries, and beaches; and sources of information and assistance. In addition, the guide offers suggestions for safe navigation and anchoring in area waters, which are subject to tidal currents due to the proximity of St. Augustine Inlet. Do not rely on this guide for navigational purposes. Instead, use the latest nautical charts. The St. Augustine Port, Waterway, and Beach District Commission provided funding for this guide, which was prepared in collaboration with the Florida Sea Grant College Program. Published April 2005.

DEVELOPING THE CONSTELLATION UNMANNED SURFACE VEHICLE PROTOTYPE

Vessel navigation through the use of reliable nautical charts is vital to ensure safe passage. Having the ability to complement this with the ability to see accurately both what lies beneath the water and ahead of a vessel in real time provides an added dimension of safety and certainty. Combining the high value and deep draft of modern super and mega yachts with a penchant for exploration creates a tension which can test the availability and accuracy of navigation charts. The development of a 2 metre remote-operated and autonomous-capable surface vehicle with ultra-high-resolution echo-sounder capability provides a unique solution which can open up considerable exploration capability. The ability to produce ultra-high-resolution images and relay these back to the mother vessel in real time enables precise seabed mapping, providing safer navigation. Additionally, it has the capability to deploy personal water-safety devices in situations such as a man-overboard incident.

Life on the Border: Dealing with Territorial Violations of the Demilitarised and Neutralised Zone of the Åland Islands

How does Finland deal in practice with instances of alleged violations of the demilitarised and neutralised zone of the Åland Islands? This is the main question in this text. We examine three levels of regulation and practice, namely international law, legislation concerning territorial surveillance and criminal law during the period 2010–2015. We examine unique materials obtained upon application. We conclude that the criminalisation presents Finland with several advantages but also some problems, in particular in matters of criminal liability. The absence of easily accessible and visible nautical and aeronautical charts indicating the coordinates of the demilitarised and neutralised zone for all those practically concerned remains a major obstacle. While the total number of reported violations remains low, the investigations confirm the continued validity of the demilitarisation regime and the intricate interplay between domestic and international law.

Satellite Derived Bathymetry Survey Method - Example of Hramina Bay

Satellite Derived Bathymetry (SDB) method uses satellite or other remote multispectral imagery for depth determination in very shallow coastal areas with clear waters. Commonly, SDB survey method can be used when planning hydrographic surveying of marine areas not surveyed or areas with old bathymetric data. This method has become widely used in the past few years. SDB is a survey method founded on analytical modelling of light penetration through the water column in visible and infrared bands. In this article, SDB method was applied by using free-of-charge Landsat 8 and Sentinel 2 satellite images to get the bathymetric data in the area of Hramina Bay in the Central Adriatic. SDB processing procedures and algorithms were described. Processed satellite data was uploaded on geodetic software and ENC S-57 format. The bathymetric map of Hramina Bay obtained by the SDB method was compared with the approach usage band Electronic Nautical Chart (ENC) HR400512 with satisfying positional and vertical accuracy.

Razvoj nove metodologije za automatizirani odabir mjerenja dubine na nautičkim kartama

Razvoj nove metodologije za automatizirani odabir mjerenja dubine na nautičkim kartama

Multispectral Multibeam Echo Sounder Backscatter as a Tool for Improved Seafloor Characterization

The establishment of multibeam echosounders (MBES), as a mainstream tool in ocean mapping, has facilitated integrative approaches towards nautical charting, benthic habitat mapping, and seafloor geotechnical surveys. The combined acoustic response of the seabed and the subsurface can vary with MBES operating frequency. At worst, this can make for difficulties in merging the results from different mapping systems or mapping campaigns. However, at best, having observations of the same seafloor at different acoustic wavelengths allows for increased discriminatory power in seabed classification and characterization efforts. Here, we present the results from trials of a multispectral multibeam system (R2Sonic 2026 MBES, manufactured by R2Sonic, LLC, Austin, TX, USA) in the Bedford Basin, Nova Scotia. In this system, the frequency can be modified on a ping-by-ping basis, which can provide multi-spectral acoustic measurements with a single pass of the survey platform. The surveys were conducted at three operating frequencies (100, 200, and 400 kHz), and the resulting backscatter mosaics revealed differences in parts of the survey area between the frequencies. Ground validation surveys using a combination of underwater video transects and benthic grab and core sampling confirmed that these differences were due to coarse, dredge spoil material underlying a surface cover of mud. These innovations offer tremendous potential for application in the area of seafloor geological and benthic habitat mapping.

Shallow Water Empirical Remote Sensing Bathymetry Using the Blue/Green and Red Spectrum Regions

An atmospherically corrected Sentinel-2 image and a 1/25000 scale nautical chart were used to investigate the performance of the electromagnetic spectrum blue/green and red regions in bathymetric data retrieval. The imaging optical empirical remote sensing bathymetry, using Stumpf (2003) reflectance model was adopted in this investigation. In clean water depth (3.1-7.3) meters both spectrum regions can be used to retrieve bathymetric data with an accuracy of ± (0.82-1.10) m. The optimum electromagnetic spectrum regions in this depth range were the blue/green spectrum range (0.457-0.523 μm) and the red range (0.773-0.793 μm). For depth range (2.1-15.5) m, the blue/green spectrum region (0.457-0.523 μm) produced better results than those of the red region. The clean water derived bathymetric data quality decreases with the increase of water depth in general and with the red spectrum region in particular. The blue/green spectrum region (0.457-0.523 μm) and the red spectrum region (0.773-0.793 μm) correlation coefficient values can be adopted as a measure of the water turbidity, using the characteristic of the water depth strong correlation in turbid water.

Early Modern Nautical Charts and Maps: Working Through Different Cartographic Paradigms

Abstract Of all the technical and scientific developments that made possible the European maritime expansion, the nautical chart is perhaps the least studied and understood. This fact is very surprising as it was with the information contained in those charts, and later imported to geographical maps and atlases, that the newly discovered lands were first shown to the European nations. There was, however, a deep incompatibility between these two cartographic paradigms—the nautical charts and the geographical maps—which remained unsolved throughout the sixteenth century and beyond, despite the attempts to harmonize the technical principles of Ptolemy’s Geography with the advances of nautical cartography. An eloquent symptom of such incompatibility was the difference between what was understood as an accurate depiction of the Earth, in the eyes of cosmographers and geographers, and what was considered by the pilots as an accurate nautical chart. The misunderstandings around these issues during the early modern period and the unsuccessful attempts at reconciliation were, in great part, the cause for some polemics among cosmographers, cartographers and pilots, such as the conflict in the Casa de Contratación around the charts of Diego Gutiérrez, a fact not entirely understood by historians. At the core of the difficulty lies the circumstance that only in the present day has the true nature of the nautical chart, as a navigational tool, started to be clarified. How the differences between geographical maps and nautical charts contributed to shape the History of Cartography in various periods, and how they are related to conflicting scholarly objectives and practices, is the subject of this essay. We will show, using the results of cartometric analysis, that not only were those artifacts constructed using different principles and with different purposes, but that they belonged to incompatible cartographic paradigms, and we will argue for the relevance of this fact for the history of science.

Los primeros instrumentos de navegación que viajaron a América

The Quatri partitu en cosmographia pratica i por otro nombre llamado Espejo de navegantes by Alonso de Chaves (b. ca. 1492 - d. ca. 1586) is a Spanish treatise on navigation considered to be an exceptional text because, for the first time, it collects all the theoretical and practical knowledge necessary for the instruction of the new pilots appointed by the Seville Casa de Contratacion [The House of Trade] (1503-1790). The Casa was the institution in charge of assessing a candidate’s proficiency for the post of piloto mayor (chief pilot), the indispensable position for navigating to the New World. After a period of internal discussion, the Casa de Contratacion stated to teach with a new point of view, abandoning the pre-eminence of the practical knowledge based on the experience of sailors for a more scientific approach to the development of navigational tools (i.e., nautical charts and instruments). Quatri partitu en cosmographia pratica is the expression of that change, halfway between medieval tradition and the new period that opens to the science of astronomy and cartography in the Age of Discovery.

The Updating of the Nautical Chart Number 69 on Java Sea Area for Safety Navigation of Sailing

Indonesia is the largest archipelagic country in the world that has become one of the main routes in international marine trade by contributing 40% of all international marine trade routes. The importance of waterways in international trading demands the existence of nautical chart for navigation. Time after time, the sea changes, therefore nautical chart needs to be update especially on the area that has a high marine traffic density such as Java Sea which currently has developed an electronic map for navigation, however paper charts are still needed for planning shipping line, the navigation on small boats and backup of charts on large ships. The aim to be achieved from this research is the availability of the latest paper chart which is appropriate with IHO standard S-4, INT1 (symbols, abbreviations and terms used on charts), INT2 (the boundary lines, gradient, grid and linear scale) and Chart Number 1. Updating chart number 69 was created by using data Electronic Navigation Chart (ENC) Northen part of Central Java region, data raster paper chart number 69 the ninth edition of the second expenditure, survey data 2017 in Cirebon and the Eastern part of Java Sea and Indonesian Notice to Mariners number 11-29 year 2017. Data obtained from the Pusat Hidrografi dan Oseanografi TNI-AL. The software used in production of nautical chart is Paper Chart Composer (PCC). Then it was added the updated data and information to the chart. The result of production a chart were corrected using digital and manual quality control analysis to eliminate errors in the process of production chart. As a result of updating nautical chart number 69 is that some of the objects that had been corrected have errors so it needs to be repaired until no more errors occur. The updating paper chart was already matched to standard IHO S-4 and INT1. The visualization of paper chart in accordance with the standard IHO INT2 and Chart number 1. The avaibility of paper chart number 69 with the update of data on the area of the Java Sea has been accomplished and can be used by mariner to navigation.

Sub-Antarctic Auckland Islands Seafloor Mapping Investigations Using Legacy Data

This paper demonstrates the richness of data collected for nautical charting and considers ways in which chart data can support scientific research, through a case study of two modern navigation surveys undertaken in the Auckland Islands. While legacy charts have coarser resolution, and may synthesize different epochs together into one final product, we examine how they may be used on their own and to complement more recent hydrographic surveys. We argue that the hydrographic and ancillary data, only a fraction of which appears on the final chart, also has scientific value and that the hydrographic surveying principles applied during data collection are equally relevant for all seabed mapping. While the benefits of full bottom coverage obtained by state of-the-art multibeam surveys are clear, there is much more to be discovered in legacy singlebeam datasets than what is displayed on the nautical chart alone.

Consideration of Level of Confidence within Multi-Approach Satellite-Derived Bathymetry

The Canadian Hydrographic Service (CHS) publishes nautical charts covering all Canadian waters. Through projects with the Canadian Space Agency, CHS has been investigating remote sensing techniques to support hydrographic applications. One challenge CHS has encountered relates to quantifying its confidence in remote sensing products. This is particularly challenging with Satellite-Derived Bathymetry (SDB) where minimal in situ data may be present for validation. This paper proposes a level of confidence approach where a minimum number of SDB techniques are required to agree within a defined level to allow SDB estimates to be retained. The approach was applied to a Canadian Arctic site, incorporating four techniques: empirical, classification and photogrammetric (automatic and manual). Based on International Hydrographic Organization (IHO) guidelines, each individual approach provided results meeting the CATegory of Zones Of Confidence (CATZOC) level C requirement. By applying the level of confidence approach, where technique combinations agreed within 1 m (e.g., all agree, three agree, two agree) large portions of the extracted bathymetry could now meet the CATZOC A2/B requirement. Areas where at least three approaches agreed have an accuracy of 1.2 m and represent 81% of the total surface. The proposed technique not only increases overall accuracy but also removes some of the uncertainty associated with SDB, particularly for locations where in situ validation data is not available. This approach could provide an option for hydrographic offices to increase their confidence in SDB, potentially allowing for increased SDB use within hydrographic products.

Magenta and alternative red colour spectroscopy on nautical charts in the visible and near-infrared electromagnetic spectrum

The International Hydrographic Organization (IHO) publishes Regulations and Technical specifications for the official nautical charts in order to standardize the use of colours to all hydrographic offices of IHO Member States. The use of magenta is reserved for highlighting, drawing attention and to distinguish information to elements of a chart of maritime importance and it is necessary to ensure its visibility.So far, there is no information on the spectrographic composition of colours intended to highlight specific content. For the first time, spectroscopy of magenta and alternative red colour is performed on the charts of hydrographic offices that have officially published colour compositions. Spectroscopy extends beyond the visible area to the near-infrared part of the electromagnetic spectrum. The article presents the absorption curves of magenta and red colour that contain information on the spectrographic composition of these colours in the visible and near-infrared spectrum. The purpose of the study is to show what proportion of black colour added to magenta or red can give positive response or positive absorption properties in the near-infrared part of the spectrum. The results are also part of preparatory research aimed at introducing colour twins, a system of hidden graphical elements designed to protect nautical charts from forgery and to expand their information content.

Geomorphology of a Harbor-Breakwater Beach along a High Sand-Supply, Wave-Dominated Great Lakes Littoral Cell

Mattheus, C.R.; Diggins, T.P.; Boyce, C.; Cockrell, J.; Kruske, M., and VanWinkle, M., 2019. Geomorphology of a harbor-breakwater beach along a high sand-supply, wave-dominated Great Lakes littoral cell. Journal of Coastal Research, 35(1), 41–55. Coconut Creek (Florida), ISSN 0749-0208.The geomorphology of a breakwater beach along Lake Superior's high-energy SE margin is investigated from aerial photographs, historic nautical charts, and ground-penetrating radar imagery to provide information on littoral dynamics. The study goal was to address shoreline behavior and depositional architecture of the expanding beach in the context of hydrodynamic changes over the last century. Understanding influences of variables such as wave climate, lake level, and winter-ice cover on breakwater-beach development has many coastal management applications, particularly along highly modified coastlines characterized by fragmented littoral cells. Subsurface architectural models of the wedge-shaped Grand Marais beach and shoreline reconstructions are evaluated in the context of hydrologic data. Statistical analyses suggest that although event-based shoreline changes can create lasting depositional architectures, multiyear to decadal patterns of beach development are driven largely by hydrodynamic trends that affect littoral sediment delivery, alter the beach face directly, or both. Periods of above-average wave-height maxima coincide with increased beach growth phases, while high lake levels favor a reduction therein. The direct geomorphic effects of increased erosion through beach inundation and stronger wave climate appear to outweigh influences of higher littoral sediment inputs from increased bluff erosion upstream and accelerated rates of longshore transport. This dynamic stands in contrast to that observed for systems along the southern Lake Erie margin, which are highly sensitive to upstream changes in sediment input. Winter-ice-cover extents and durations are statistically nonsignificant or marginally convincing drivers (low R2) of beach geomorphology.

MODIFICAÇÕES NA GEOMORFOLOGIA MARINHA A PARTIR DE ESTRUTURAS PORTUÁRIAS: O CASO DO MUCURIPE, FORTALEZA/CE

O litoral de Fortaleza/CE apresenta desde o século XIX importantes alterações na linha de costa, principalmente devido a obras portuárias e de estruturas mitigatórias de erosão. A pesquisa teve como objetivo analisar a evolução batimétrica do litoral norte de Fortaleza desde o início de operação do porto do Mucuripe em 1945. A área de estudo foi delimitada pelo espigão do Titanzinho e o emissário submarino, porém foi enfatizado o entorno portuário. Foi realizada a construção de modelos digitais batimétricos a partir das cartas náuticas da Diretoria de Hidrografia e Navegação – DHN entre 1945 e 2014. Evidenciou-se devido às constantes intervenções antrópicas a presença de dois setores: um adjacente a ponta do Mucuripe, com o substrato diretamente modificado por atividades de gerenciamento portuário e um segundo setor, que seria o restante da área submersa até o emissário submarino. O primeiro setor é marcado pela criação de áreas eminentemente deposicionais devido ao molhe do Titã (efeito sombra hidrodinâmica), Titanzinho (barramento da deriva litorânea) e pelo Píer (devido ao efeito sombra do Titã e do avanço da bacia de evolução). Verifica-se que o sotamar do Titã e entornos do Píer foram sucessivamente dragados desde a década de 1950, além da criação do canal de acesso do porto na década de 1970. O segundo setor é marcado pela presença dominante de feições arenosas, destaca-se um banco longitudinal subparalelo a linha de costa de cerca de 2 Km². Esta feição apresentou grandes variações espaço-temporais desde a instalação das estruturas portuárias, no entanto a sua gênese estaria relacionada a duas possíveis origens: efeito morfodinâmico do promontório do Mucuripe no redirecionamento dos processos (pretéritos e atuais) e/ou como uma antiga barreira costeira, que posteriormente foi afogada devido à elevação do nível relativo do mar no Quaternário Superior. Destacam-se quatro complexos rochosos – o Recife do Meireles, o Recife Grande, a Pedra do Justin, e o Recife da Velha. No fim do setor dois (praia da Leste), tem a presença do emissário submarino com cerca de 3 km de comprimento e uma área de descarte de sedimentos dragados. Este setor se apresenta parcialmente modificado pelas estruturas portuárias, onde as principais alterações ocorrem nas proximidades da linha de costa (espigões e enrocamentos). Verifica-se que a morfologia do litoral submarino de Fortaleza apresenta grandes modificações (aprofundamento do leito, criação de altos sedimentares) nas proximidades do Porto do Mucuripe e na linha de costa, devido às estruturas rígidas de proteção e operação portuária.

The Sea Mile and Nautical Mile in Marine Navigation

The problem of differences between the sea mile and the international nautical mile has been analysed. Algorithms for the calculation of sea miles with applications in different sailing methods on the ellipsoid that can be easily incorporated in modern microprocessor controlled navigational devices are proposed. These algorithms can also be employed on an outfit of large-scale nautical charts with a double scale in sea miles and international nautical miles.