INTERNATIONAL HYDROGRAPHIC REVIEW 
MAY 2020 
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adopt BSCD2000 as the name of their chart datum without having to actually change their 
charted depths. Therefore, this section only gives an overview about the general situation in the 
respective countries. Table 2 summarizes the national geodetic reference frames, positioning 
services and HRS realizations that can be used with BSCD2000. Regularly updated details about 
the implementation status as well as instructions for users, e.g. leaflets, are provided via the 
CDWG website (http://www.bshc.pro/working-groups/cdwg). 
In Sweden and Finland, a calculated MSL has been used as reference level (chart datum) for 
nautical charts and water level information. The reference level for regularly updated epochs 
(estimated present-day MSL) was estimated from long time series of annual mean values of 
mareograph observations. Depths from printed charts needed to be converted semi-automatically 
by means of a correction formula in order to correct for the time difference and to make the chart 
ed depth compatible with the provided water level information. As motivated in Section 2, this 
two-step approach implied a lot of work to keep the nautical products updated and consistent. At 
the same time, it was not straightforward and error-prone for the mariner. 
Thus, decisions to make a transition to BSCD2000 in Sweden and Finland have come a long 
way. In Sweden, both water level information and 50% of all nautical charts are now using 
BSCD2000. In Finland, part of the bathymetric and chart data have already been transformed to 
BSCD2000. Water level information is ready to be provided in BSCD2000 when first charts will be 
published in the new datum. Figure 7 details the estimated height of the current calculated MSL 
relative to BSCD2000 for selected mareographs in Sweden and Finland. 
5' 10' 15’ 20' 25' 30' 
5' 10’ 15’ 20' 25’ 30' 
Figure. 7: Differences between the reference levels of the old national chart datums with respect to Baltic Sea 
Chart Datum (BSCD2000). In Sweden and Finland, the old reference levels are equal to the 
calculated MSL in the year 2020 (according to different national conventions). The values from Norway shows the MSL 
over the period 1996-2014, relative BSCD200(f N20 °°. In Estonia, Latvia and Lithuania, the Kronstadt reference level is 
used as old chart datum. In Poland, the local Polish Height System Amsterdam NH SS is used as chart datum. Notice 
how postglacial rebound reduces the magnitude of the calculated MSL relative BSCD2000 in the Bay of Bothnia; it is 
now just a few cm close to the location of maximum uplift. The values are taken from BOOS (2020).