"Old" sediments in the "New" Inde River?

12/05/2020
Relocation of the Inde River Copyright: V. Esser

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The project "Floodpollution" deals with the distribution of sediment-bound pollutants by flood events:

 

To the project: Floodpollution

In the past, the river catchment of the Inde River was strongly influenced by ore mining and smelting, brass industry, coal mining and many other related industries. In the region of Stolberg and Eschweiler this caused anthropogenically increased levels of heavy metals, for instance, zinc, lead, and copper in the environment and also in the river sediments. Of particular interest in the project is an approximately 13 km long river relocation in the lower reaches of the Inde River, which became necessary due to the ongoing mining in an opencast lignite mine. This newly built, natural near river reach was connected to the Inde River in 2005. As building material for the completely new riverbed the substrate "Forstkies" was used, which is characterized among other things by low background concentrations of various trace elements. These background concentrations are lower as the typical value ranges at the Inde River upstream.

Investigations of riverbed samples within the relocated river reach show that between 2005 and today there has been an accumulation of, for example, zinc, copper, and lead in the river bed, which is characterized by contents that are significantly higher than the background contents of "Forstkies". The analysis of flood sediments showed that this accumulation is due to sediment-bound pollutant transport, which is mainly controlled naturally by flood events. Within this context, upstream river reaches play the key role in these processes.

You can find more on this topic in: A decade of fluvial morphodynamics: relocation and restoration of the Inde River (North‑Rhine Westphalia, Germany)