ICH Metadata Web Portal Now Available

After a few teething problems which caused a long delay, the ICH Metadata Web Portal is now available via the coastalhydography.com website.

This aspect of the project was to develop an on-line, GIS enabled data management system that allows users to upload, and query geospatially referenced metadata (data about data) on past and future hydrographic surveys. The metadata includes essential information such as survey location, purpose, ownership, status, sensors, specifications and age. Spatial and non-spatial searches allow the user to discover what data exists, gauge its quality and value and request the data through an automated email service. Data holders will then be able to agree their own terms for releasing the data.

As organisations are able to upload in real-time, metadata of their recent or forthcoming surveys, this will present a real opportunity for the coastal monitoring community to explore possibilities for collaboration in forthcoming surveys, and thereby potentially reduce the cost to each participating organisation. The site is fully compliant with OGC interoperability standards, and the partnership is actively investigating real time data sharing with other metadata portals. This will significantly increase the ability of the online marine community to access a broader range of up to date meta-datasets across the entire UK coastal zone.

Bathymetric Lidar Survey Completed

A test survey has been conducted in the approaches to Plymouth to evaluate the

accuracy and target detection capabilities of a typical Bathymetric LIDAR system. Baseline data has been collected using more conventional sensors, such as Simrad

EM3000 and Atlas Fansweep 20 multi-beam echosounders, as well as single-beam

echosounder data. The LIDAR has been flown over the same area, enabling statistical and visual comparisons to be made.

Bathymetric LIDAR systems typically operate by firing laser pulses into the water and recording the reflections from the sea bed. Some systems use the first and second returns from one primary laser, whilst others rely on using two different frequencies (one red, one green) and recording the different returns. The aircraft are positioned using state-of-the-art GPS aided inertial measurement units, and can obtain depth measurements as dense as a 2x2m grid – well in excess of 3 million points per hour. LIDAR is particularly effective in the very shallow coastal fringes, where taking soundings from boats becomes more and more difficult.

Several Bathymetric LIDAR companies were invited to bid for the test survey, and the

company chosen from this competitive tender was Tenix LADS, based in Australia. LADS flew two sets of survey lines at differing “sounding” densities – 5x5m and then 3x3m. A review of the results is underway and planned to be published in a future paper.

LIDAR Desk Study

The first phase of this study will consist of a series of four detailed maps of UK waters with coloured coastal zones indicating the estimated depth to which bathymetric LIDAR will penetrate are to be created. Each map will represent one quarter of the year. Colour banding for LIDAR depth penetration for the above maps will be <5m, 10m, 20m, 30m, >30m. A report detailing the investigations which were undertaken to derive the above maps will also be created.

Based on the results of the first phase of the study, up to four of the selected areas shall then be chosen for further investigation. The further investigations shall include;

• Site visits to prominent areas of coast within the selected area to observe local conditions.

• Study of large-scale maps to determine where the proximity of high land and obstructions may interfere with Lidar operations..

• Visits to any local airports which may be utilised during operations to determine facilities for both Dash 8 aircraft and Twin Otter aircraft.

• Visits to local experts (e.g. harbour masters, dive companies etc) to determine local conditions including level of boat traffic and subjective knowledge of water clarity and field conditions.

• Extra boat field-work where necessary.

• Investigation detailing any adverse impact of particular seabed conditions (e.g. kelp).

Object Detection Trials near Plymouth

As part of the bathymetric LIDAR evaluation survey, it was decided to test the object

detection capabilities of the system as well as the overall depth accuracy. Tenix LADS state that their system is IHO Order 1 capable (SP- 44 Fourth Edition), which means that the system must be able to measure the depth within a given accuracy (approximating +/- 26cm in 40m of water), as well as detecting a 2m cube in up to 40m of water.

Overall depth accuracy is determined by first producing a reliable reference surface by tried and tested means. The data acquisition for this reference surface will have much higher levels of redundancy than a conventional navigation survey. The test survey is then conducted so as to include the reference surface area, thus providing baseline data for comparison. However, the only reliable method of proving or disproving target detection aspects of the IHO specification is to have a target of known dimensions on the seabed, and then attempt to robustly identify it with your sensor. Knowing the exact dimensions of a pre-existing target in not easy, so it was decided for the test survey to construct and deploy a 2m cube.

The ICH Cube was constructed from a steel frame, with GRP panels attached to the sides. Finally, the top of the cube was coated in sand to mimic the seabed in the area of deployment.

Since the cube was deployed in September, a number of different survey systems have used the opportunity to undertake target detection tests in the area, including Reson 8125 and 8101, Simrad EM 3000, Atlas Fansweep 20 and a Submetrix system. None of the system suppliers were informed of the exact location, as such targets are often initially acquired, then lost in the data post-processing. It’s obviously not much of a test if the operators know where the target is!

Due to the concerns over the ICH Cube being a potential navigational hazard, it has been collected and is being stored ashore. It will be redeployed for future trials - please contact us if you would like to know the new test area (approximate position of course!).

And Finally…

For further information or to comment about any element of the ICH project, please

contact info@coastalhydrography.com, or see the web-site at www.coastalhydrography.com.

The Invest to Save Budget is a joint venture between Treasury and the Cabinet Office. It provides funds to encourage two or more public bodies to jointly reconfigure elements of their work or to initiate new processes to provide innovative, streamlined or simply better modes of service.

The Environment Agency is a non-departmental public body sponsored largely by

the Department for the Environment, Food & Rural Affairs (DEFRA), and the National

Assembly for Wales. Its 10,000+ staff provides high quality environmental protection and improvement in England & Wales through an emphasis on protection and education – and vigorous enforcement where necessary. MCA is an Executive Agency within the Department for Transport, Local Government and the Regions (DTLR). As the UK’s national regulatory body for marine safety, its primary task is to develop, promote and enforce high standards of maritime safety and pollution prevention. Its aims are: to minimize loss of life amongst seafarers and coastal users; to respond to maritime emergencies and to minimize the risk of pollution from ships.

Ordnance Survey is Britain national mapping agency. It is widely regarded as the world leader in its field, which covers the production, maintenance and marketing of a wide range of maps, computer data and other geographical information for business, leisure, educational and administrative use. Ordnance Survey maintains large-scale topographic mapping down to the mean low-water mark.

The UKHO is an Executive Agency within the Ministry of Defence. It is the world’s leading supplier of navigational charts and publications, and the UK’s national hydrographic authority. Its mission is to meet national, defence and civil needs for charts and other hydrographic information in support of safe navigation. Increasingly, UKHO is providing this information in digital formats.

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