Research

Within the thematic fields of geomorphology and paleohydrology, the Herget research group  focusses on the following topics:

Dam failures and outburst floods

Beside the reconstruction of former dam-lake outbursts, investigations on recent natural dam-lakes are taking place in order to verify how stable the dams are or what dimension a flood would have in the event of a dam breach. Natural dam-lakes can be formed by the blockage of river courses by landslides, volcanic eruptions, glacial ice, moraines or tectonic uplift. Often, these dams are not stable enough to permanently hold the retained water. This can result in unexpected outburst floods that can be many times larger than weather-related floods.

Herget, J. & L. Gregori (2020): Outburst flood from Möhne Reservoir in May 1943 after aerial bombing. In: Herget, J. & A. Fontana (Hrsg.): Palaeohydrology - traces, tracks and trails of extreme events. Cham (Springer), S. 49-64

Bohorquez, P., P.A. Carling & J. Herget (2015): Dynamic simulation of the catastrophic drainage within the basin of late-Pleistocene glacial-lake Kuray-Chuja, Altai Mountains, Southern Siberia. International Geological Review

Herget, J., Euler, T., Roggenkamp, T. & J. Zemke (2013) Obstacle marks as palaeohydraulic indicator of Pleistocene megafloods. Hydrology Research, 44, 2, S. 300-317

Two natural dam-lakes of Ikhnach,  The upper lake results from a rockslide of the adjacent mountain flank, that built up a natural dam, while the lower lake is dammed by a Pleistocene end moraine.
© Jürgen Herget

Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
© Hendrik Meurs

Reconstruktion of historical floods

The working group deals with the reconstruction of historical floods as well as with their transfer to present flood hazards. For this purpose, first of all historical flood marks and textual records are used as essential clues for the reconstruction of floods. With further consideration of the topography of the floodplains in historical times, the peak discharges and thus the characteristics of such floods can be estimated by hydraulic calculations. In order to derive a current flood hazard from these results, it is then necessary to adapt them to the anthropogenic reshaping of the riverbeds, the current hydrological conditions of the catchment area and the climatic conditions.

Roggenkamp, T. & J. Herget (2022). Hochwasser der Ahr im Juli 2021 – Abflussabschätzung und Einordnung. Hydrologie und Wasserwirtschaft 66, H. 1, S. 40-49.

Herget, J., Roggenkamp, T. & M. Krell (2014). Estimation of peak discharges of historical floods. Hydrology and Earth System Sciences 18 (10), S. 4029-4037

Roggenkamp, T. & J. Herget (2014). Reconstructing peak discharges of historic floods of the River Ahr, Germany. Erdkunde 68, S. 49-59

Elleder, L., Herget, J., Roggenkamp, T. & A. Nießen (2013). Historic floods in the city of Prague – a reconstruction of peak discharges for 1481-1825 based on documentary sources. Hydrology Research, 44, 2, S. 202-214


Process research

The working group has two hydraulic test channels, which are used not only for research purposes, but also in university teaching. In these, the formation processes of various fluvial small forms on the channel bed are experimentally reconstructed and statements about the discharge conditions are derived. This includes, among other things, the analytical investigation and simulation of flow fields and sediment displacements in flowing waters under changes in individual influencing factors.

Schlömer, O., P. E. Grams, D. Buscombe & J. Herget (2021): Geometry of obstacle marks at instream boulders - integration of laboratory investigations and field observations. Earth Surface Processes and Landforms 46(3), S. 659-679

Euler, T., J. Herget, O. Schlömer & G. Benito (2017): Hydromorphological processes at solitary boulder obstacles in streams. Catena 157, S. 250-267

Scour in the hydraulic test channel
© Thomas Euler

Römerhafen Kalkar (2).JPG
© LVR Bodendenkmalpflege

Geoarchaeology

Geoarchaeology is the interface between cultural and natural sciences. In the Herget working group, anthropogenic finds from historical times are used to draw conclusions about the natural and hydrological conditions at the time.

Roggenkamp, T. & J. Herget (2019) Rekonstruktion der römerzeitlichen Rheinhydrologie – Methode und Ergebnisse. In: Bemmann, J. & M. Schmauder (Hrsg.): Der Rhein als europäische Verkehrsachse III. Bonner Beiträge zur vor- und frühgeschichtlichen Archäologie Bd. 22, S. 79-91

Roggenkamp, T. & J. Herget (2016). Middle- and Lower Rhine in Roman times – a reconstruction of hydrological data based on historical sources. Environmental Earth Sciences Bd. 75, H. 14.

Roggenkamp, T. & J. Herget (2016). An extreme drought in the year 69 AD on Lower Rhine. Zeitschrift für Geomorphologie Vol. 59, Suppl. 3, S. 99-109

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