16 July 2021

Inden: a river changing course, eroding an old channel and flooding an open cast mine

Posted by Dave Petley

Inden: a river rediscovering a previous course and flooding an open cast coal mine

The floods in Germany, Belgium and Netherlands this week have been truly catastrophicThe same storm system also caused flash flooding in London.  It is likely that the this event will have triggered landslides, but we will need to wait to get more information when the priority is rescue and recovery.  There are suggestions that an event has killed several people near to Cologne, but we await further information.

In the meantime, my attention has been drawn to a very interesting event at Inden in Germany, the site of a very large open cast coal mine.  Here, the extreme rainfall has caused a small river to change course, partially flooding the mine.  It is worth taking a moment to review the events.  The Google Earth Image below shows the site – I have annotated the key features:-

The setting of the floods at Inden in Germany on 14 July 2021.

The setting of the floods at Inden in Germany on 14 July 2021. Image from Google Earth.

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The pertinent features here are the small river flowing towards the north from the bottom of the image, and then swinging around to flow twowards the west (presumably rerouted around the mine),  An abandoned river channel is clear, with a large bend around the building:-

The abandoned channel at Inden in Germany.

The abandoned channel at Inden in Germany. Image from Google Earth.

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In the rainstorms of 14 July 2021 the small river has burst its banks and reoccupied its former course.  The effects are dramatic.  This video captures the huge erosion that has occurred as the flood has occupied, and down-cut, its channel:

https://twitter.com/cheetah_spotty/status/1415693905916538881

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The water has flowed into a very large open cast coal mine, causing serious damage.  There are videos on Twitter showing thgis in action:

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And this image shows the aftermath:-

The aftermath of the flooding event at Inden in Germany.

The aftermath of the flooding event at Inden in Germany. Image by Guido Jansen via Aachener Zeitung.

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For a river to change channel during a flood is not unusual.  In this case, the base level of the channel has been reset by the mining operations.  The erodible materials then allowed the river to down-cut, creating the new, deeply incised watercourse.

The European floods are another example of global heating playing out in real time with tangible impacts.  The last few years have demonstrated that regional effects are already intense, generating extreme temperatures and extreme rainfall, with a lot more heating baked into the system.  I can only add my agreement to that of others, as expressed in a BBC article today – we don’t know exactly how much trouble we are in, but we do know that it’s very bad indeed.