Fachbeiträge

Sämtliche Fachbeiträge aus den Hydrographischen Nachrichten seit der Ausgabe HN 100 sind online verfügbar.
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The search for Malaysian Airlines flight MH370

Even today, hydrographic surveys can reach the boundaries of what is technically possible, and project sizes as presented in this case study will push our ingenuity. The size-challenge can be defined by the extent of the project area, the water depth, the number of vessels/equipment involved, the data volume or all of the above. On 8 March 2014 the Malaysian airplane MH370 scheduled on a flight from Kuala Lumpur to Bejing with 239 people on-board went missing. This tragedy started a marine search and rescue mission, which turned later into the largest aircraft accident investigation in history. This case study presents a summary of the underwater search of this investigation. The mainly uncharted search area in the southern Indian Ocean of 120,000 square kilometres reaches water depths of up to 6,000 metres. The operation was planned in three phases: a deepwater multibeam survey to map the seafloor and enable a detailed search, the detailed survey to find the aircraft, and at last a recovery survey.

aircraft search | ultra-deep survey | deep-tow system | Indian Ocean

Ausgabe: HN 105 Seite: 44–46
DOI: 10.23784/HN105-09
Autor/en: Melanie Barth

Offshore unexploded ordnance recovery and disposal

Millions of tons of unexploded ordnance (UXO) and discarded explosive remnants from war can be found in European waters and beyond. Many of them are next to the shoreline, dispensing toxics to the environment. Dumping of ammunition, military practice and warfare are the main source for this large amount posing a risk for the offshore industry besides the undeniable impact this also causes to the environment. With increasing utilisation of offshore areas, the activities in offshore UXO clearance have increased. Due to the governmental commitment and planning of increased usage of offshore wind energy in Germany, research has been conducted to solve the technical question of unexploded ordnance recovery and disposal. Within the last five years, the market for offshore UXO detection and removal has multiplied as well as experience increased, research has also lead to better analytical results during the UXO survey campaign which has helped achieve fewer false alarms. Better techniques and the development of specialist equipment for the removal results in smaller time frames in which the clearance can be done as well as lower risk for equipment and personnel. Research is also being conducted on how to handle ammunition safely which is classified as not save to transport without the normal demolition procedure.

UXO | unexploded ordnance | investigation | metal detector | recovery | disposal | underwater positioning

Ausgabe: HN 105 Seite: 40–42
DOI: 10.23784/HN105-08
Autor/en: Jan Kölbel, David Rose

Improved positioning of surveying vessels on inland waterways with HydrOs

Surveying vessels are equipped with GNSS receivers or GNSS-INS coupled systems respectively to determine their position. By receiving and processing a correction signal, which is provided by a network of continuously operating reference stations, they determine a precise GNSS real-time kinematic (GNSS-RTK) solution. Thereby, the multibeam echo sounder observations can be georeferenced in order to produce a map of the channel bottom. One crucial point of the entire workflow is the quality of the vessel position which is highly influenced by the surrounding topography. For instance, bridges or buildings can cause multipath effects, refraction or a complete loss of signal reception. Often, even the correction signals cannot be received. Then, no RTK solution can be determined. To mitigate such gaps in the GNSS-RTK trajectory, an adjustable multi-sensor system called Integrated Hydrographic Positioning System (HydrOs) was developed as a joint project of the German Federal Institute of Hydrology (Bundesanstalt für Gewässerkunde) and the Institute of Engineering Geodesy at the University of Stuttgart.

GNSS | positioning | Extended Kalman Filter | hydrographic multi-sensor system | outlier testing

Ausgabe: HN 105 Seite: 34–38
DOI: 10.23784/HN105-07
Autor/en: Thomas Artz, Annette Scheider, Marc Breitendeld, Thomas Brüggemann, Volker Schwieger, Harry Wirth

ENC and ECDIS

Electronic Navigational Charts (ENC) and Electronic Chart Display and Information Systems (ECDIS) are typically created at different places: ENCs by various hydrographic offices, ECDIS by various industrial ECDIS manufacturers. When in use, ENCs and ECDIS form a closely interconnected »community« with its members strongly dependent on each other when creating results which aim to support the navigator as efficiently as possible. Recognising the complexity of the standardisation task a great deal of success has been achieved in creating a worldwide community of producers and users of ECDIS and ENCs providing a global coverage for the international maritime community. However, gaps exist between worlds of ENCs and ECDIS with regard to the standards and methods applied when producing and using ENCs and ECDIS. Some of these discrepancies between the worlds of ENCs and ECDIS have the potential to mislead the navigator and other users.

ENC | ECDIS | bathymetry | zooming in | S-57

Ausgabe: HN 105 Seite: 30–33
DOI: 10.23784/HN105-06
Autor/en: Peter Dugge

Use of laser bathymetry at the German Baltic Sea coast

The German coastal waters are quite shallow. The idea arose to use airborne laser bathymetry (ALB) for hydrographic surveying of near-shore areas of the German Baltic Sea. Since these waters are relatively turbid, it became necessary to investigate to what extent modern ALB systems could be of practical use in an area large enough for hydrographic purposes especially in the Baltic Sea. The basic questions to be answered by the project were: Which areas can be measured by this method? And how expensive will this be in relation to traditional methods? From 2012 to 2014, four test surveys have been accomplished in an area north of the city of Wismar. During these surveys, many relevant questions were solved.

ALB | laser bathymetry | Baltic Sea | Secchi depth

Ausgabe: HN 105 Seite: 26–28
DOI: 10.23784/HN105-05
Autor/en: Wilfried Ellmer