As it Was

by a not so old Hydrographer
"Land in sight", a cry soon to be followed by "Clew up the main", to reduce speed. It is 1606 as the Dutch ship Duyfken makes first recorded landfall in Australia. But this is not simply landfall: Duyfken, under the command of Willem Janszoon, charts the first 200NM of the Great Southland: Australia. During this exploration of the East Coast of the Cape York Peninsula contact was also made with local Aboriginal people. The Dutch, as sixteenth-century European traders and carriers of goods such as grain and herring from the Baltic and salt and spices from the Iberian peninsular, fought... (read more)
2008-01-01 01:00:00

Improving Overall Resolution of Bathymetric Survey

Integrated Use of Multi-beam Echo Sounder and Towed Interferometric Sonar
Designing offshore engineering facilities requires large amounts of information. To acquire it, suites of engineering and geophysical surveys are run, which as a rule include such techniques of seabed and sub-bottom investigation as seismic profiling, acoustic, magnetic and bathymetric surveys. Obtaining accurate and detailed seabed bathymetry is extremely important because the quality of other surveys depends on the quality of the bathymetry. One of the most accurate and cost-effective ways to acquire high-resolution bathymetric data is the use of shipborne bathymetric systems such as multi-beam echo sounders (MBES) or interferometers. The drawback of this method is that the resolution of... (read more)
2012-04-19 03:50:13

Evolving Terminology

From managing property rights in marine space to the marine cadastre
With extended national jurisdiction offshore brought about by the coming into force of the United Nations Convention on Law of the Sea (UNCLOS), new territories have emerged that need to be explored, exploited, protected and shared. The oceans are being subdivided into Territorial Seas, Exclusive Economic Zones and Continental Shelves, each with attendant rights and responsibilities. Effective marine resource management in these vast coastal regions will hopefully be based on a better understanding of the interrelationships between human activities and marine ecosystems than we have had even in the recent past. UNCLOS has provided a legal mechanism whereby a nation... (read more)
2008-01-01 01:00:00

Underwater Noise Monitoring in the North Sea

Jomopans Project to Monitor Continuous Sound
Sound is of vital importance for marine animals. Eleven institutes from the countries bordering the North Sea have joined forces in the Jomopans project to implement a novel monitoring strategy for underwater sound. Due to the growth of human activities in the sea, sound pollution is a growing concern for marine environmental managers. High levels of anthropogenic noise disturb animals, but the integrated impact of noise on the marine ecosystem is largely unknown. In the Joint Monitoring Programme of Ambient Noise in the North Sea (Jomopans) project, measurements at sea are combined with noise maps from numerical modeling to assess the quantitative levels of sound at sea. Sound is of vital importance for marine animals. Eleven institutes from the countries bordering the North Sea have joined forces in the Jomopans project to implement a novel monitoring strategy for underwater sound. Due to the growth of human activities in the sea, sound pollution is a growing concern for marine environmental managers. High levels of anthropogenic noise disturb animals, but the integrated impact of noise on the marine ecosystem is largely unknown. In the Joint Monitoring Programme of Ambient Noise in the North Sea (Jomopans) project, measurements at sea are combined with noise maps from numerical modeling to assess... (read more)
2019-06-18 04:01:43

Sediment Waves

Geohazard or Geofeature?
The term ‘sediment waves’ was fully established in a special issue of Marine Geology and refers to large-scale depositional bedforms in various parts of the world’s oceans. These undulating objects usually have tens of metres to a few kilometres in wavelength and a height of several metres. The genesis is believed to be a near-bottom current, a turbidite current or both. The main issue about the sedimentary wavy features was, and is, to distinguish them from soft sediment deformations (creep). The methods used for such determinations are accurate processing of seismic sections to reveal whether the faults are real, measuring... (read more)
2013-12-04 11:25:17

The ROV in Nearshore Site Investigation

Nearshore engineering surveys are undertaken for the purpose of gathering information pertaining to the bathymetry and morphology of the seabed, along with the geotechnical characteristics and geophysical profiles of the sub-stratum. Standard practice tends to involve a low-resolution bathymetric and sub-bottom survey of the approximate area of interest, followed by a higher-resolution, site-specific investigation entailing detailed analysis of the location and form of the materials present. The traditional survey technique in the nearshore region is to use surface towed equipment and jack-up rigs, with diving teams and ROVs (Remotely Operated Vehicles) acting as support systems, performing very basic investigation tasks.... (read more)
2008-01-01 01:00:00

Improving Safety at Sea

Hydro international Interviews Pedro Pedreira
Last month we brought you a feature article on the recent progress in the European satellite navigation system, Galileo. We discussed the motivation, the funding problems and the procurement process. Here we discuss this further with engineer Pedro Pedreira, who has been executive director of the European Global Navigation Satellite System Supervisory Authority (GSA) since July 2005, which is charged to manage the development phase of the Galileo programme. Can you please introduce yourself and tell the readers of Hydro international a little about your career and how you came to be posted as the head of the European Global... (read more)
2009-03-27 12:00:00

Global Navigation Satellite Systems

A Status Update
In this feature the current status and future development of four Global Navigation Satellite Systems (GNSS) are briefly presented. These four systems are the American Global Positioning System (GPS), the Russian Glonass, the European Galileo and the Chinese BeiDou Compass. All four systems offer, or will offer, civil navigation services (publicly open), as well as restricted access navigation services, which means for GPS, Glonass and most likely for Compass as well, military services. The European Galileo system will offer so-called Publicly Regulated Services (PRS) for use by the government. The basic principle of satellite navigation – referred to as standalone... (read more)
2011-03-16 12:04:30

3D Sonar in Object Detection

Intuitive real-time imaging for sub-sea visualisation and classification
Sonar is well accepted as an option for detection and visualisation of underwater objects. Side-scan and sector-scanning sonar have traditionally been used by surveyors but whilst they produce excellent images, these are often difficult to interpret accurately. This article describes new developments in 3D-sonar and their advantages and use in emerging underwater disciplines. Classic applications for object-detection are many and varied, ranging from looking for items such as wreckage, debris, lost items and so forth to defence applications, seeking out threats such as mines. Increasingly, though, object detection has been expanded to include obstacle avoidance for both surface and submersible... (read more)
2008-01-01 01:00:00

Automated Side-scan Data Analysis

Side-scan sonar is well accepted as a tool for detection and visualisation of underwater objects and is widely used in support of safety of navigation surveys. Although side-scan sonars produce excellent images, these images are often difficult and time-consuming to review and analyse. These images typically contain spurious features and artefacts due to acoustic phenomena, such as refraction, and bottom characteristics, such as sand waves that result in a large number of false contacts. This article describes a research and development effort at Science Applications International Corporation to develop and apply advanced processing techniques in bottom target detection and image... (read more)
2007-10-03 12:00:00
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