Sandwave Migration

Seabed mobility and shallow-water swathe sounding
The use of swathe systems in a highly mobile, shallow-water environment poses significant problems for the hydrographic surveyor. Several physical factors encountered when gathering swathe data are introduced and described as contributing to degradation of the accuracy model. The extent of influence by physical/environmental characteristics and the tidal solution on bathymetry must be understood so that methods to obtain accurate bathymetry suitable for safe navigation, seabed migration modelling and future research projects can be employed by the surveyor in real time. Lack of space prevents detailed discussion of such factors here, but this by no means reduces their importance, briefly... (read more)
2008-01-01 01:00:00

Gardline Hydro

Hydrographic surveys over the whole world
Gardline has been undertaking hydrographic surveys in the north west of Europe and all over the world since 1974. Large-area nautical charting surveys to UKHO standards have been regularly undertaken since 1982 in UK waters. During this time techniques and equipment have been continually improved and upgraded to meet the changing demands of the hydrographic user community. Gardline has significant experience with regional nautical charting surveys for the UK Government. The company has been particularly successful in fulfilling contracts in UK waters in 1982, 1983, 1984, 1985, 1988, 1990, 1994, 1996 - 2003, and the current 2004/05 contracts in the... (read more)
2008-01-01 01:00:00

Amplified Sediment Waves in the Irish Sea (AmSedIS)

Understanding Big Sand Wave Behaviour
Large sediment waves are striking yet poorly understood seabed features in many shelf seas. Very large sediment waves (3–18m in height) have been documented to migrate up to 70m per year in the Irish Sea and some sand waves reach heights of up to 36m (Figure 1). Such transport of enormous sediment volumes can endanger the stability of submarine pylons, cables and pipes and they cause a highly mobile benthic habitat. To understand the dynamics of these sediment waves, we identified that we need to focus our investigation on the effects of sediment grain size variability, the availability of mobile... (read more)
2014-04-07 01:31:38

Mapping the Seafloor with Remote Sensing and Satellite Imagery

An Analysis of the Techniques and Benefits of These Methods
70% of the Earth is covered by water, but so far just 7% of it has been surveyed (Mars, Venus and the Moon are better surveyed). Hydrography as a science has changed dramatically since the first measurements were made by Alexander Dalrymple and James Cook with lead lines and sextants. Singlebeam echosounders were invented in the 1920s – a technology still used today for mapping the seafloor. This method of using echosounders can produce very high-resolution bathymetric data but the high operational costs and the slow working process make it economically unsuitable for covering large areas. However, with the ongoing expenses of... (read more)
2018-06-19 09:23:54

Technology in Focus: Multi-beam Echosounders

New Technology, New Capabilities and New Markets
The evolution of multi-beam echo sounders (MBES) is leading to systems with enhanced capabilities in their traditional markets, but also provides features to allow the expansion of their use into new areas and applications. This short review highlights some of the features of the latest generation of systems. The attributes of an MBES system are traditionally described by technical specifications, such as operating frequency, pulse length, beamwidth, number of beams and coverage. These technical parameters define the nature of the system, but the fundamental characteristics of greatest interest. By Dave Mann, Gardline Geosurvey, UK. Just as technological advances mean there... (read more)
2013-03-26 02:25:34

Autonomous Vessel as Enforcer

Patrolling Marine Protection Areas
There are currently 13,764 Marine Protection Areas (MPAs) jointly covering over 2% of the oceans. One such MPA is Malaysia’s newly formed Tun Mustapha Park comprising 1 million hectares of marine park and shark sanctuary in northern Borneo. Governance, management, effective real-time situational awareness and enforcement are essential for the preservation of the resources in these water spaces and especially the hundreds of fish species that they support. The development and deployment of unmanned surface vehicles (USVs) offers a potentially long-term and cost-effective solution. Arguably the key challenge is the scourge of Illegal, Unregulated and Unreported fishing (IUU), which has... (read more)
2016-07-26 11:55:17

Australasian Hydrographic Society

News The Deployable Geospatial Support Team (DGST), then called the Hydrographic Office Deployable Survey Unit, was originally created in the 1980s to conduct hydrographic surveying activities in Antarctica. The DGST as a small part of RAN hydrographic capability continues to evolve. It now conducts surveying tasks to meet other national charting requirements, in addition to military Rapid Environmental Assessment (REA) surveys, an activity which now places a Hydro/Metoc ship in an actual battle space as a tactical entity. The DGST is currently commanded, both in the field and at home base, by Lieutenant Commander D.G. Mullins, RAN. It is based... (read more)
2008-01-01 01:00:00

We Visited for You

Technical Awareness Seminar 2003, South Africa
In early December 2003 the Hydrographic Society of South Africa held a four-day Technical Awareness Seminar (TAS) hosted by the Institute for Maritime Technology (IMT) in Simon’s Town, South Africa. The theme for the Seminar was ‘New Technologies for a New Century’. Over one hundred delegates from the Southern Africa region attended the TAS, providing a good representation of the regions Offshore Mining Companies, Oil & Gas Industry, South African Navy, Research Institutions, Educational Institutions and Local Marine Suppliers. Delegates generally registered for just one of the four days, as presentations and demonstrations were repeated every day. However, due to... (read more)
2008-01-01 01:00:00

Unmanned Mapping of Ultra-shallow Waters

Tarragona Survey of the Riu Francoli Using an USV
Hydrographic surveying in ultra-shallow, inland and enclosed waters can prove extremely challenging and often presents increased risks and obstacles to both personnel and equipment. These considerations include health and safety issues, potential damage to equipment, lack of suitable launch sites and regions where submerged debris and physical seabed characteristics can make an area particularly hazardous to survey. In these locations, traditional manned survey vessels are often unsuitable, inefficient or incapable of completing a successful survey. In November 2016, Unmanned Survey Solutions, with support from Swathe Services, was tasked with completing a hydrographic survey of such an area.  Survey Layout Located... (read more)
2017-07-11 01:22:08

Multi-beam Error Management

New data processing trends in hydrography
The hydrographic community has tumbled headlong into a data boom. Hundreds of single-beam soundings are now replaced by millions of high-resolution multi-beam swath soundings. This boom is not free from the problems inherent in how data is to be handled by ever-shrinking staff and ever-increasing demands for ways to store, process and archive gargantuan datasets. Luckily, modern computer hardware and processors can handle the load. However, there is still the issue of affording resources for traditional data processing, where each sounding is scrutinised. What new software approaches are being developed to automate processing? This article describes one new and innovative... (read more)
2008-01-01 01:00:00
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