Chart Datum, Water level and Currents Working Group (CDWCWG)

“To implement a common reference system, S-104 and S-111 in the Baltic Sea”

Photo: Chart Datum, Water level and Currents Working Group 2nd meeting, 25-26 March 2025, Tallinn, Estonia

The Working Group should

Report to the BSHC Conferences.

To continue implementation of the Baltic Sea Chart Datum 2000 (EVRS with land-uplift epoch 2000).
To prepare the road map for transition, including e.g.:
- to establish a network of relevant bodies involved into the transition and efficiently communicate and give guidance within this network
- to invite relevant bodies to inform the users
- to review of progress of national plans and actions
- to propose harmonization actions.
To cooperate with relevant bodies on water level related issues e.g.:
- to promote studies on the validation, status and distribution of water level information, and to promote studies on interpolation and prediction of water levels
- to promote studies on displaying schemes for joint Baltic Sea water level information
- to promote studies on recommendations to IHO bodies how the sea level and its variations should be shown on nautical paper and ENC charts and publications, and conveying water level information to mariners [ref. IHO Technical Resolutions].
To support development of a common harmonized height reference, including further development of a common geoid model for the whole Baltic Sea area:
- to promote geoid computations and gravity measurements in the Baltic sea, as is needed to realize the Baltic Sea Chart Datum 2000
- to coordinate the finalization of the BSCD2000 height reference grid
- to establish a continuity management (future updates) of the BSCD2000 height reference grid
- to distribute BSCD2000 data products
- to support geoid and oceanographic studies relevant to these purposes.
To cooperate with relevant international bodies, for example organizations responsible for delivering water level and currents information (e.g. BOOS, NOOS) and geodetic infrastructure (e.g. EUREF and NKG).
To liaise with relevant IHO bodies and study relevant IHO resolutions and specifications.
To coordinate the implementation of the IHO S-100 products S-104 Water Level Information and S-111 Surface Currents in the Baltic Sea:
- to invite meteorological and oceanographic institutes to the working group to strengthen the implementation.

Members

List of Members

Activities

Information about Baltic Sea Chart Datum 2000

The Baltic Sea Chart Datum 2000 (BSCD2000) is a geodetic reference system adopted for Baltic Sea hydrographic surveying, hydrographic engineering, nautical charts and publications. It is based on the definitions for the European Vertical Reference System (EVRS). The height reference surface of BSCD2000 is the equipotential surface of the Earth’s gravity field. The zero level of BSCD2000 is in accordance with the Normaal Amsterdams Peil (NAP). The reference epoch for height and depth changes due to the postglacial land uplift in Fennoscandia is 2000.0. Mean sea level and difference to the old reference datum relative BSCD2000 (pdf, png) currently varies from a few cm at the entrance to maximally approximately 25 cm in the middle of the Baltic Sea.

BSCD2000 is about to be adopted as unified chart datum by all the countries around the Baltic Sea and also agrees with the national height systems used on land. BSCD2000 will facilitate effective use of GNSS methods like Galileo, GPS and GLONASS for accurate navigation and hydrographic surveying in the future. A more detailed specification of the BSCD2000 can be found here.