Ruhr dating com
Ce type de transformations de surface n’est pas visible sur le terrain et nécessite une comparaison de modèles topographiques numériques afin de les mettre en évidence.La valeur moyenne de l’abaissement de la surface a été calculée à partir de l’ensemble des cartes numérisées et analysées : elle varie de 0,51 m sur la carte de Kamen, ville située à la frontière orientale de la région de la Ruhr, à 5,16 m sur la carte de Gelsenkirchen, dans la plaine alluviale centrale de la Emscher d’une surface totale de 128,5 km².
The valuable comments of the reviewers are gratefully acknowledged.
In order to protect the Ruhr District from severe flooding problems much of the area has to be drained by a large number of pumping stations, although mining has ceased in the southern and central part of the Ruhr District (Peters, 1999).
In some locations not only troughs, wetland areas or lakes occur in the most subsiding areas but also larger hills like the “Mechtenberg” in Essen, which is located in the middle of a subsidence area with a surface lowering of approximately 20 m.
As a result, the highest values of subsidence, amounting to more than 25 m, were observed within the coalfields of the former coal mine “Zollverein” which is distinguished for its long mining history and its World Heritage status.
Two examples from the cities of Essen and Dortmund analysed in detail reveal that not only depressions but also elevation features are affected by mining subsidence.
Besides positive forms of landscape disturbances such as heaps, there are numerous negative forms resulting from ground surface subsidence frequently filled with water.