Influence of 200 years of water resource management on a typical central European river. Does industrialization straighten a river?

Abstract

Background: Over the last 200 years, the courses of most European rivers have experienced significant irreversible changes. These changes are connected to different kinds of anthropogenic river use and exploitation, which have varied from running water mills and rafting to large-scale hydroelectric power plants, industrial water withdrawal and flood protection measures. Today, in most developed countries, water quality and ecological river development are important factors in water management. The aim of this study is to evaluate the specific impacts of different time periods during the last 200 years on river courses and their effects on current river management using the example of the 165-km-long German Rur River (North Rhine-Westphalia). The Rur River is a typical central European upland-to-lowland river whose catchment has been affected by various phases of industrial development. Methods: In this study, a range of morphological changes over the last 200 years are determined based on historic maps and up-to-date orthophotos. River length, sinuosity, oxbow structures, sidearms and the number of islands are used to investigate human impact. The results are correlated with historic time periods. Results: This analysis shows that river straightening increases, especially during the Industrial Revolution, even without direct hydraulic channelization. The period and grade of river straightening have a direct morphodynamic impact on today’s river restorations. Since the Rur River is a typical upland-to-lowland river, the results show an additional impact by geofactors, such as landform configurations. Conclusions: Morphodynamic development is correlated with five historic periods of industrial development between 1801 and 2019 up to the introduction of the EU—Water Framework Directive (EU-WFD). Each period shows a different influence on the watercourse, which is connected with human intervention. Even if worldwide comparisons show that the five historical phases differ slightly in their timing between regions, they are applicable to other study areas.