The Danish-German Border
The Danish Agency for Climate Data has authority for maintaining the Danish-German border. The border was established in 1920 following the end of the First World War. Based on stipulations in the Treaty of Versailles, a plebiscite was held on national affiliation in North Schleswig, in accordance with international law.
The maintenance of the border and other practicalities relating to the new border were laid down in a treaty between the two countries. The treaty describes the practical maintenance, which takes place in cooperation with the German authorities, including the holding of a joint border inspection every ten years.
The course of the border and the legal documentation are set out in the so-called border atlas, which, with text, survey sheets, and coordinates, details the reality as it was over 100 years ago.
Over the years, changes have occurred. Some have been man-made, but mostare natural. 75% of the border follows waterways, which adapt their natural course over time – a so-called labile border. These changes must be documented in so-called amendment protocols, which are prepared and signed jointly by the implementing authorities from both countries. The documentation is therefore incomplete without all the amendment protocols.
The physical markers indicating the border in the landscape are placed based on an underground network of buried drainage pipes. The original coordinates are described based on the Prussian Cadastre Polygon Network from 1873-1875. The physical markings, both the visible and the essential underground ones, have therefore been measured and published in Soldner coordinates with the centre located in the town of Ostenfeld.
Border Inspection Every 10 Years
According to the treaty, a joint border inspection is held every 10 years. The inspection has a clear technical purpose, namely to ensure that border stones and posts are visible. But another important purpose is to consolidate the good cooperation, especially on the many coinciding and sometimes overlapping authority tasks on both sides of the border. Responsibility alternates between the two countries, and it is therefore only every 20 years that Denmark’s turn comes around. The first inspection was held in 1924, and in 2024 Denmark had the honour of hosting the inspection on the 100th anniversary of the event.
Digitilisation of the Border Atlas
The many border markings along the border are getting old. Many of them are now 100 years old and time has taken its toll on them. The underground fixed-point network of buried drainage pipes is particularly worn down. Many of the drainage pipes have been lost, and others are difficult to access. The time, technology and cooperation are ripe to secure the physical attributes and documentation. At the 2024 inspection, the Commission therefore recommended that the implementing authorities jointly undertake a modernisation and harmonisation by surveying and calculating in modern systems. The work has begun and will continue until the next inspection in 2034.
Geodetic Advice to the Ministry of Foreign Affairs Regarding Boundary Demarcation, Primarily at Sea
The Danish Agency for Climate Data provides geodetic and technical assistance, including participation in working groups appointed by the foreign services of the negotiating countries when disagreements arise over maritime areas. Bilaterally as well as multilaterally. In the coming years, the so-called Continental Shelf Project will mainly give rise to negotiations between the countries involved.
As an example, the most recent agreement can be mentioned. From 2018-2023, The Danish Agency for Climate Data participated in negotiations between the Kingdom of Denmark and Canada on a comprehensive agreement (KoD-CA agreement) in the waters between Greenland and Canada. Previously, attempts had been made on several occasions to reach an agreement, and this time it succeeded, in the spirit of the Ilulissat Declaration.
Facts about the KoD-CA Agreement
The KoD-CA agreement resolves three disagreements: 1. modernisation and extension of the existing agreement from the Arctic Ocean to the Labrador Sea. 2. the line crosses Hans Island in Kennedy Channel, which was divided in separate negotiations. 3. overlapping claims to the continental shelf in the Labrador Sea.
The division of Hans Island ended the so-called Whisky War, where for more than 50 years people had taken turns proclaiming sovereignty over the island in a peaceful manner, by placing their national flag and a bottle of whisky or similar as a gift to the opposing side.