The Swedish Maritime Administration aims to, in databases and products containing geographical information use the geodetic reference system in plan and elevation supported by the Swedish National Land Survey. In 2005 a new national height system was introduced, RH 2000 (Swedish National Height System 2000). It provides significantly better accuracy than older systems and is designed for modern satellite-based measurement operations and navigation. It is also built on international recommendations, creating better opportunities for coordination with other countries.
The Swedish Maritime Administration has begun the process of adapting their databases and products accordingly. The depth database was converted in 2013. For the chart database, which serves as the source for all chart products, this is a much more comprehensive undertaking. This transition will therefore be gradual and the aim is that it will be completed by the end of 2020. A new chart, 5342 Gävle (produced in 2014), along with its related larger scale plans and ENC cells, are the first chart products to have RH 2000 as the reference level.
A Common Reference Level
With the introduction of RH 2000, all charts and products will refer to a common chart datum. The traditional way of referencing depth information in Swedish charts, by specifying a mean sea level for a given year (typically the chart production year), has meant that there are a variety of reference levels used throughout the entire product portfolio, even in adjacent and overlapping products.
It will also become easier to correct chart depths against current depth, as one no longer needs to take into account the uplift in the same way as before, but primarily correct for the current water level.
Lakes and canals have a specific chart datum, but they already have, or will have, a definition of their level relative to the zero level in the RH 2000. For example, Malaren’s chart datum is +0.78 m RH 2000.
International and National
There is currently an international collaboration aiming to develop a common chart datum for the Baltic Sea Region and a proposal has been made for it to be called Baltic Sea Chart Datum 2000. RH 2000 is a valid implementation and application of this in Sweden.
RH 2000 is also becoming an increasingly used and accepted height system in both the public and private sectors in Sweden. That it is now also used for hydrographic information facilitates projects and activities which include both land and water, for example infrastructure projects, wind power at sea, flood simulation, landslide risk analysis, etc.
For further information, see the adjacent links.