To fulfill its official responsibilities for surveying, mapping and registration of geographic information in Denmark, the National Survey and Cadastre has conducted three country-wide surveys of the Danish landscape. These took place in 1891, 1944 and 1990.
Comparisons between these surveys reveal changes in the landscape and help to improve the accuracy of altitude models that are based on a changing average sea level. The most recent trigonometric survey is the foundation for the DVR90 altitude system that is currently being promoted in Denmark.
Historically, altitude has been more difficult to determine than latitude and longitude. Precise calculations of altitude can be critical with relation to coastal erosion, storm warnings and flood management. This is also the case when environmental information about transnational phenomena like rivers and weather is shared across borders.
Therefore, The National Survey and Cadastre has developed a close working relationship with the Danish Meteorological Institute, the Danish Maritime Safety Administration, The Danish Coastal Authority and a number of ports and harbours. Together, these institutions have developed surveying and measurement techniques to improve the Danish altitude system.
The National Survey and Cadastre has official responsibility for the management and maintenance of Denmark’s survey network and for ensuring that altitude data is available to the country’s local authorities. This includes carrying out detailed trigonometric levelling surveys in conjunction with local and regional updates to the Danish altitude system. Such updates have been carried out in the majority of the country’s communes.