Feasibility study to assess contaminants in sediments as a result of the July 2021 flood in the transition from the Mittelgebirge to the lowlands.



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  Collage of the flooded Rur floodplains and the sampled flood sediments Copyright: © PGG / IWW Figure 1: a)-b) Flooded floodplain of the Rur River near the village of Einruhr. c-d) Sampled flood sediment. e) Dried sediment samples in the physical-geographical laboratory of the chair, which will be analyzed to detect various pollutants.

Between July 13 and 16 in 2021, an extreme flood occurred in parts of North Rhine-Westphalia and Rhineland-Palatinate. In North Rhine-Westphalia, the districts of Aachen, Düren, Euskirchen, Heinsberg, and the Rhine-Erft district were affected. An initial comparison with flood hazard maps generally indicates an extreme flood event.

In addition to flooding (see figure 1a), which can lead to immense damages of property and individuals, flood events cause on the one hand the remobilization of contaminated sediments, which are stored in the floodplains of industrial regions from former times, and on the other hand the input of pollutants from flooded settlement areas. These pollutants can be deposited in floodplain areas (see Figure 1c and d), gardens, roads, et cetera.

  Bar diagrams showing the contents of zinc, lead, and copper in riverbed sediments Copyright: © Maaß et al. (2018) Figure 2: Riverbed samples of the Inde River between source and mouth and the corresponding contents of zinc, lead and copper in the longitudinal river profile.

The region near the cities of Stolberg and Eschweiler was shaped by a wide-ranging industrial history. Due to ore deposits, mining activities and metal processing industries, significant enrichments of various heavy metals can still be found there today in riverbed and floodplain sediments (Figure 2).

On the one hand, the project deals with hydrological and hydraulic assessments of the flood event in the region of Eschweiler / Stolberg. Among other things, the extent and intensity will be investigated in detail. On the other hand, numerous samples were taken (Figure 1c and d). Various analyses will be carried out on water, sludge and sediment samples to determine the pollutant content. Finally, these results will be compared to those of other riverbed and flood investigations from past projects in order to evaluate the influence of this extreme event on the dispersion of pollutants and the contamination of the rivers Vicht, Inde and Rur.

Maaß, A.-L., Esser, V., Frings, R.M., Lehmkuhl, F., Schüttrumpf, H., 2018. A decade of fluvial morphodynamics: relocation and restoration of the Inde River (North-Rhine Westphalia, Germany). Environmental Sciences Europe 30, 40.

Duration 9 months

DFG Sachbeihilfe

Principal investigators

Prof. Dr. Holger Schüttrumpf – Institute for Hydraulic Engineering, RWTH Aachen University

Prof. Dr. Frank Lehmkuhl – Chair for Physical Geography and Geoecology, RWTH Aachen University