Minutes of the 9th North Sea Hydrographic Commission Resurvey Working Group (RWG) Geodatastyrelsen, Aalborg, Denmark. 24th-25th September 2019

published at internal, NSHC, Resurvey Working Group | 0

Welcome and Opening Formalities

Welcome from Chair and introductions

  • Introduction of all attendants. Chair thanked DK for hosting.


  • BE: Johan Verstraeten
  • DE: Bernd Vahernkamp
  • DK: Lars Hansen
  • NL: John Loog
  • SE: Ulf Olsson
  • UK: Phil Payne (Chair), Hannah Doddrell (Secretary), David Parker (UKHO), Andrew Colenutt (MCA – Observer)

Apologies – DK: Jesper Vedel, FR:  Vincent Lammare & Mikael Le Gleau

Adoption of minutes of the 8th Meeting

  • All agreed, no issues raised.


Adoption of Agenda

  • Chair – Importance of Item 4 as directed by NSHC, offshore wind farm policies has been added in at request of the UK.
  • Invite for other action items.
  • The agenda was adopted..


Review of actions from 8th RWG

  • Supplied in Annex A
  • It was raised as an issue that we are relying on one person for website updates – Chair to discuss with DE
  • Review of Actions undertaken (Annex A): summary of key points below:
    • Action 4-8th RWG: wording needs to be amended as it is more that survey specifications are being supplied. In addition, the internal website needs to be more organised to make it easier to find these documents.
      • Creation of Actions 1-9th RWG and 6-9th RWG (Annex B)
    • Actions 7 and 8-8th RWG: carried over into Action 2-9th RWG – Chair to confirm the link before everyone can check their links on the IHO Website.
    • Supply of CATZOC and Survey Interval Polygons – to be on-going actions and have been added to Actions 3 and 4 for the 9th RWG
  • On a general note it was raised that all MS can be contacted for specifications whilst they are awaiting upload to the website
  • FR were unable to attend 9th RWG but supplied all responses to actions via email prior to the meeting: DE to upload them all to the internal website for MS to review (Action 7-9th RWG).


Review of TOR

  • Amendments have been accepted by the commission.
  • No requests for further changes
  • Query over other member states attendance (Iceland, Ireland, Norway) – Chair confirmed they have been invited
    • There could be a possibility to push for further attendance at commission level once we have completed the risk map
  • As a result of Action 1-9th RWG the TOR Section 1.13 now needs to be amended to include survey specifications – Action 5-9th

Updates on NSHC and EU Developments since the 8th Meeting

Items of note from 33rd NSHC (Chair)

NSHC endorse current plan for work on risk map. They want the WG to continue working on this and are expecting the CSB paper that will be discussed during this meeting. Discussion took place on how we can best supply to the risk map that is easy to understand to the NSHC.


Status of Bathymetric Data Model/Website Developments (DE)

There has been one addition to home page, which were the minutes of the 8th RWG. There have been no additions from other working groups such as the Tidal WG. The North Sea Hydrographic Model, which is hosted on the EMODnet was updated in September 2018. Higher resolution data is available from the UK and NL. Data can be downloaded survey by survey, its yet to be deconflicted.

With regards to the internal site DE have started uploads and will continue to upload documents sent. Separate folders will be added to the internal section of the website to make things tidier (Action 6-9th RWG). The CATZOC work from last year has been completed and includes IMO boundaries and shipping routes. Once missing polygons have been provided (Action 4-9th RWG) the maps will become more harmonised. UK highlighted that their polygons are CATZOC capability of survey to account for charting issues that may downgrade the final charted CATZOC.

Once this work on CATZOCs has been completed the RWG can decide whether to take it to other working groups (e.g. Quality Standards WG). SE raised the question on how we can represent better than CATZOC A1. NL commented that CATZOC links to S57 so it will not change and everything else such as S44 needs to align. Discussion over how special users require special charts so how do we communicate this?

  • Action 8-9th RWG: SE to outline the issue over how we can better represent CATZOC A1 for special users for review by RWG and Chair for any further action and discussion as appropriate.

It was highlighted that the internal site is confidential to this group to allows internal discussion, without immediately going public.


Development of Harmonised Risk Map

We now have a CATZOC layer and a survey interval layer following the last meeting. Chair believes once all missing polygons have been provided/colours have been aligned then it’s a good start and this was agreed by all MS. DE raised the question of whether we should only be depicting for <40m of water. Response from the Chair was that if we cut out deeper waters it detracts from where survey is missing. Discussion over whether the next data layer could be depth (if so, should it be 50m as the new S44 uses 50m rather than 40m), which led into discussion to the overall purpose of the harmonised risk map.

It was agreed that it isn’t to change the way each nation works but to allow discussion on a harmonised level on why areas are surveyed at different levels especially at national boundaries (is it national prioritisation rather than a high-risk area?). It was highlighted that for the UK the working group has already been beneficial in the DWR areas over the Dover Straits.

Discussions took place over seabed mobility and whether MS require a seabed mobility layer. NL bases risk on depth, mobility and shipping traffic. UK raised that S100 could consider temporal quality of data. Other discussions were had over how change in depth overtime and the position of controlling depth overtime need to be considered.

  • Action 9-9th RWG – NL to inform Group about Smart Sea Project
  • Action 10-9th RWG – Put into chairs report that the RWG view there is a position to work together and harmonise for seabed mobility. We now require technical input. Mobility to be added as an agenda item at next meeting.

Discussion over the interval map, led to Decision 1-9th RWG: Update survey interval map as heat map rather than separate colours. Darker colours will be areas surveyed most frequently and Action 11-9th RWG: All MS to provide/update their polygons for interval rather than surveyed and planned. In line with intervals agreed last year. DE to update map as heat map rather than separate colours.

It was agreed that once the two outputs are finished then it can be presented to the commission stating that we are using for our cross-boundary’s discussions.

Update on National Developments

BE:  Update on survey plans and prioritisation

BE gave a review of the Belgian Sea Area and an update on Marine Spatial Plan 2020-2026, which was published in July 2019. HO is focusing on new wind farm areas, which have T0 MBES coverage in place. Existing areas under the 2014-2020 plan have some resurvey areas being increased. Second focus is calibration areas for acoustic equipment and the development of a quality assessment tool for bathymetry, backscatter and obstacles. General MBES coverage policy covered: in 2017 Flemish Minister declared it a high priority for the whole continental shelf, good progress is being made and larger areas are being covered by contractors. Improved processing tools such as Auto-Clean are in place. Innovation project for unmanned survey vessels are underway. BE are currently trialling remote-controlled surveys focused on ADCP and autonomous surveys at sea.

DE:  Update on survey plans and prioritisation

Danish border completed, working more in the North now. Survey being undertaken in Western German Bight in the shipping route, using Fugro OceanMap system for corrections. There are research projects and new survey methods being used especially around wind farms. Working with the NL to survey River Amstel. Upcoming/on-going work on GNSS corrections, LAT model for German Bight (includes work from Tidal WG). Demonstration of morphological modelling work undertaken given and shows movement of sand waves/dunes.

DK:  Update on survey plans and prioritisation

Carrying on with surveys for the new routing systems along with SE as outlined at the 8th RWG. Resurvey policy hasn’t yet been defined as awaiting analysation of the data, but first findings show reefs that won’t require much resurvey. Area B was surveyed in 2018, and Area A will be done in 2019. All to be published by Summer 2020. Virtual reference systems (VRF) have been used. Data will be published as CATZOC A1. No additional work yet planned. Maritime authority has done a risk assessment based on general depth and traffic – all low risk.

FR:  Update on survey plans and prioritisation

Unable to attend but provided considerable written notes. Documents will be uploaded to website that were provided prior to meeting (Action 7-9th RWG)

NL:  Update on survey plans and prioritisation

Policies haven’t changed, over the next couple of years vessels will be updated. One vessel currently in the Caribbean. Wind farms are causing some issues (to be discussed in later agenda items). Study being undertaken to look at the impact of wind farms on morphology. Not anticipating too much survey effort in wind farms. Smart Sea Project underway to establish relationship between risk and survey effort (details to be provided under Action 9-9th RWG). However, not looking too promising at this stage but updates will be provided to the RWG. Undertaking topographic and bathymetric lidar on St Martin in the Caribbean; working with FR.

SE:  Update on survey plans and prioritisation

Working to survey approx. 5000km2 with two survey vessels. No procurement of surveys planned in 2019 but continuing with own resources. Hopeful for new EU projects in years to come. Resurvey plan has intervals of 3-10 years covering 15 areas (mainly harbours and narrow channels). Survey data from pre-wind farm building is given to the HO. Survey plans for 2020-2021 and beyond 2022 – 16000km2 remaining, if no further EU funding then 9000km2 to be surveyed by 2022. By the end will be up to 75% of Swedish waters completed. Long term plans for the remaining 25% of waters, which may be less navigable so work being undertaken to determine how it will be funded. SE survey for shipping industries, who pay fees when passing, which is fed back into survey work. Autonomous survey potential for the future.

UK:  Update on survey plans and prioritisation

Update given by MCA on UK CHP. Shallow programme undertaken 2018/19 was made up of 6 surveys. Surveys in North Wales have been in partnership with Welsh Coastal Monitoring Programme. Medium programme undertaken 2019/19 was made up of 5 surveys. 2019/20 programme underway and includes 9 shallow water surveys and 6 shallow to medium surveys. USVs being used in the shallow to medium programme. Potential for lidar in Scottish areas. 18 routine resurveys planned for next year off the East coast. Discussion over use of USV’s. UK view to date that its’ the human input/integration of data at end of project causes the most issues. Report to follow on efficiency of USV’s vs. manned vessels in the next year.


Policies on Surveying in and around Offshore Wind Farms

Discussion led by UK and that how they hope that MCA will issue guidance requirement that areas should be surveyed including areas where shipping may be migrated/moved as a result of the wind farm development. MMO issues licences but MCA give criteria for it including requirements for S44 Order 1a surveys for before, after cable construction and at decommissioning. There hasn’t been any enforcement for data to end up at UKHO for charting. The assumption is that they can be reduced in priority from survey planning if they are surveyed through other requirements. Do other MS have other experiences/policies?

DK – energy companies do surveys, which are supplied to the HO who then do not survey the area. The Ministry of Environment set out the specifications with the consultation of the HO. No-go zones during construction but once completed you can enter, and they are therefore considered in survey plans.

SE – there are issues in economic zones because of traffic avoiding wind farms but TSS’s are usually in place to control this. Once completed anchoring is banned in wind farm areas.

UK – sea zone is open for navigation. NL are consulted for traffic impacts by the UK aren’t consulted by other MS. Discussion over who has consultations. There has been consultation between SE and DK.

NL – wind farms are closed with a 500m safety range requiring permission to enter under the Mining Law. Licences are issued by Economic Affairs. There are many wind farms near shipping routes, which could cause other issues if ships get into trouble and cannot enter the area. To-date they have not had post-construction bathymetric surveys (hope to get this going forward), surveys are for engineering purposes, UXO searches, cable search at end.

  • Action 13-9th RWG: Share contact details for licencing for wind farms for upload to website

Chair raised the question of: should the RWG be looking at wind farms closer and can we review the information that may impact shipping and therefore resurvey plans?

  • It was decided to add a standing agenda item so that this can be a discussion piece each year including on how it may be impacting resurvey plans – Decision 2-9th RWG and Action 12-9th

There was a discussion over whether MS retain their SOLAS responsibility in wind farm areas and whether MS get regular data supply from developers along with discussions over dumping areas and survey standards for developers. DE just removed depths and contours from the chart.  SE check for S44 Order 1a and data is supplied to the SMA.

It was concluded that all MS have similar weakness relying on third party surveys, the risk is still there, and that policies and systems are lacking – they need to end up with charting authority and meet a standard


Applicability of Alternative Survey Techniques

Crowdsourced Bathymetry including review and comments on RWG CSB Paper ‘To investigate how CSB can be used to support / resurvey activity in the North Sea region.’

Chair introduced commissions requirements. A draft paper was distributed prior to meeting based on the IHO CSB guidance paper that was reviewed at the 8th RWG. Opened up for comments from the group:

SE – there are issues with receiving data that has such shoal depths compared to the chart, they may need to go out and verify the data. Unverified data causes issues for charting. SE are using CSB to consider safety of navigation but not for large scale publishing. SE tend to use it to assess where further work may be required.

UK – if you have multiple reports it could help prioritise surveys. UK also highlighted that we have been doing CSB on a small scale via H-notes for a long time, we are now looking at a change of scale. UK do chart with notes and these depths often stay on the chart for long periods of time.

NL – evaluation of large CSB datasets is challenging for resourcing as we are more likely to get it in. Evaluation is also based on underlying data. (Section added to the report on Large Datasets).

DK – trials have been undertaken using OLEX data to verify chart accuracy in Greenland and assess future charting requirements/find any NM worthy data. However, data cannot be extracted under the basic licence. OLEX licence for office use is £750. Norway have an agreement with OLEX that they can use their ENCs as background in return Norway can use the data. You need to be able to validate the data and it needs to be better than what you already have. You need to use intelligent CSB (section added to the report).

Discussions over how you can store depth data and the use of OLEX and GEBCO.

It was agreed that we need to clarify in the paper what crowd sourcing is and on what scale of surveying it falls (what about when bathymetry isn’t the primary purpose of the work? – should we consider putting surveyors on-board?). Another example that prompted this was that is monitoring via ferries truly CSB? But it also isn’t systematic survey work.

Considering the view that this is going up to the commission a section was added to the report to consider liability.

Discussions took place over the use of satellite imagery such as Google Earth. UK are currently considering this and using it but usually for areas that have already been decided on to go and survey. NL say this is CSB. DK are using this for identifying shoals and rock awash in Greenland in areas they wouldn’t go to. Agreed we shouldn’t include satellite imagery for this report and should clarify in introduction it is about acoustic data.

UK said we should be doing difference analysis on CSB data to identify issues rather than using it for charting. There was a discussion over what you difference against; should be the ENC or chart.

NL raised that we need to be S44 compliant – CSB isn’t a substitute for surveys but agreed it is good for checks and planning.

Discussion over whether CSB is data coming into us or is it us going out and getting it (e.g. OELX and NOAA) and the resource issues associated with this. IHO push for trusted companies to collect data in crowd sourced way. Then discussed how we are moving away from using data just for SOLAS purposes. Discussion over how master mariners tend to use depths as gospel – DK study in Baltic only found that only 5% were aware of CATZOC and how to use it – section added to report for awareness of quality by mariners, which will consider the paper produced by Data Quality WG.

Focus on whether CSB is supporting resurvey activity in North Sea region. It was agreed that it can be used for flagging areas of concern even if it just comes from fishing vessels. It can be used to prompt further surveys in more capital areas/areas that aren’t resurvey regularly rather than areas that are resurveyed annually.

Issues over the lack of metadata was discussed; at least if you had date/time you can do tidal corrections. Also, data and time is important for differencing and comparing data temporally. Again, raises an issue if resourcing.

Overall discussions led to two actions:

  • Action 14-9th RWG – incorporate discussions, new sections and agreements into CSB Paper
  • Action 15-9th RWG – MS to provide studies/experiences of CSB for inclusion in paper


Satellite Derived Bathymetry

UK – didn’t have any work to report around the North Sea (low appetite to do this in the UK) but have worked in the Pacific (Kiribati & Tuvalu). UK chart to CATZOC C where they have enough data to prove what’s good/bad data. Data has been used for charting in areas of atolls. First time round there was no ground truthing and surveyor was left to create their own project. Second year of work asked for no smoothing or interpolation and this gave very poor overlaps; up to 2m vertical gaps, still working to fix this. Different working abroad because of getting resources and the current quality of charting. UK have extended ground truthing via Stereo Imagery.

NL – do not use SDB in the North Sea region but have used fixed radar stations to detect wave patterns and changes in bathymetry.

BE – test undertaken with EOMap, found that general features were detected generally well but several meters difference in areas they know well therefore not good not for charting purposes.

SE – do not view it as suitable but they use auto and stereo photo and spectral analysis for their entire shoreline, the work is nearing completion. 2m was depicted very accurately and has been tested via vessel.

DK – RWG were joined by the Danish Geodata Agency SDB specialist – they have been undertaking testing on the West coast of Greenland– analysis is ongoing, raw imagery and uncalibrated data has been received but they are only getting one value per pixel (error must be accounted for). Only a few places where you can check against MBES. Had data from 2 suppliers and have seen differences of up to 7m between the 2. 2m uncertainty isn’t the issue its not know where it is working/correct. Their conclusion was that it’s not viable in areas of traffic that are vital for under keel clearance but could be for other uses.

DE – no experience with SDB, but like SE they use imagery to provide high resolution imagery for planning survey lines and detecting changes in coastal regions.

Discussions took place over SAR – UK have used it for offshore infrastructure detection and DK stated that it can be used for detecting oil spills. Discussed that the agenda could also include airborne methods of survey.

  • Action 16-9th RWG: MS to provide studies/experiences of SDB and airborne work for upload to website


Autonomous Surveying

UK work under the CHP covered under national updates. Also mentioned that work has been undertaken with the National Oceanography Centre in the Caribbean. UK have also been working with the Channel Coast Observatory for shallow water work where they are obtained S44 1a with MBES to drying 2m. A trial has been undertaken using a fixed wing drone for photogrammetry – special order reached but awaiting proof.

DK have been used drones in Greenland but stated that it is difficult to put images together at the end. Further to this they have used the drone in a pre-planned route and the obtained imagery is used on-boards vessel to show potential dangers. Challenges associated with this are getting qualified personnel, cost, permissions, weather and the risk of losing the done.



Discussed how REIGL and RAAMS can now go on drones but there are restrictions as must be within your line of sight, but less costly than planes. UK are still working with Lidar outside of the North Sea Region and invited MS to get in touch if they require any advice. Density requirements have been pushed up this year to get 9 hits per 2m2 bin, but object detection is still an issue. In addition, 10cm resolution imagery also collected. Not received 1a dataset to date. Otherwise validated like any other bathymetric dataset. UK about to trial lidar in North Sea area where MBES already held (early 2020) – looking at whether it can meet S44 Order 1a object detection by comparing to MBES, then look at doing 0-5m with lidar and stitch to MBES with some overlap. Secchi information is being collected beforehand.



Discussion over information sent from FR –

As part of the preparatory work for the award of concessions for MRE parks, the shom contributes to the elaboration of preliminary studies (bathymetric, sedimentology, swell, tide, currents synthesis).These preliminary studies are used to feed the public debate for the choice of the area of establishment (area selected at the end of the public debate of around 300km²). The Ministry of Environment funds these preliminary studies. Once the area of establishment is chosen, the Ministry of Environment commissions various public operators to carry out preliminary studies:

  • Météo France for wind measurements
  • AFB (French Biodiversity Agency) for biological observations
  • And Shom for hydrographic data: MBES, SSS, surficial sediments, swell, tide and currents measurements
    Geophysical measurements (seismic and geotechnical drilling) are directly contracted by the Ministry of the Environment with private service providers, as Shom is not in a position to carry out these measurements.

The results of these technical studies are then provided to candidate operators as part of the competitive dialogue launched by the State for the award of the concession. To date, there is no active MRE concession in French waters. Concession operators will have to monitor the impact of the facilities on the environment (physical and biological impact). Shom may intervene at the level of the scientific and technical committees and may issue opinions and recommendations on the measurement protocols put in place by the operators. We are interested in the measurement protocols put in place by the other hydrographic services for preliminary and follow-up studies of the MRE parks.

Discussed whether anyone has involvement in legislation for MRE Parks?  – No, everyone else imposes it upon the contractor as discussed under wind farm section. There is an action in place to provide details (Action 13-9th RWG).

BE – Smart Sea Project workshop is taking place on 8th November 2019 in the Netherlands (BE to confirm the location and whether an invite to the Chair of the RWG would be sent).

SE – It would be useful to have a collection of work done for autonomous surveys.

  • Action 17-9th RWG: UK (MCA) to provide details/potential visit on autonomous survey work



Future Direction of the Working Group

Chair is encouraged by the work we are conducting; the frequency is appropriate, and everybody agreed it has been useful. This will be passed up to the commission. There was a discussion over travel for future meetings; could we alternate between remote meetings (e.g. Skype) and face to face meetings or co-locate with the timing of other events (possibly Offshore Energy Oct. 2020). Agreed we have time to look into this.

  • Action 18-9th RWG: Plan for Netherlands 2020 but assess other options to potentially have a remote meeting (All MS to provide details of systems used). Trial a small test prior to commission meeting. If remote in 2020 Netherlands will host in 2021


Closing Formalities and Farewell

Adoption of new list of action items

  • Supplied in Annex B.
  • All agreed and to be done by Christmas for website work to be completed in January ahead of the NSHC meeting in March.


Next Meeting and discuss UKHO Chair and Rep for next meeting

  • Next meeting discussed above.
  • All content for UK to continue Chairing.

Leave a Reply