The river Rhine was subject to major morphologic alterations during the 19th century. Due to intensive
human intervention in the morphology (river straightening, channelization and embankments) and in
the sediment balance (weirs of power plants and sediment extraction), the flow and especially the
sediment transport of the Rhine River changed dramatically. The measures resulted in an increase in
sediment transport capacity while at the same time reducing sediment input, so that the Rhine River
is aiming to create a lower bed gradient by deepening the bed. This condition would bring the sediment transport capacity into balance with the reduced sediment input and with the flow in the constricted and straightened river course. However, negative consequences of this development have been evident for decades. These range from the uncovering of less erodible sediment layers, which are an obstacle to ship navigation, to the undermining of bridge piers, the lowering of the groundwater level and a variety of negative ecological consequences, which result in a sharp reduction in biodiversity.
In order to optimise the efficiency of spending on countermeasures and the related monitoring and
research programmes, a coherent overview of all activities in the Rhine basin and of the state of
knowledge on the sediment balance is needed. The objectives of CHR, the International Commission
for the Hydrology of the Rhine Basin, which commissioned the project, are to produce a coherent
overview of the activities, in particular with regard to sediment transport in the Rhine basin, to identify
gaps in knowledge and make appropriate recommendations for supplementary monitoring
programmes and for the opening of a new research programme. The results of the study also form a
scientific building block for the activities in the ICPR, on the subject of sediment management, as
envisaged in the Rhine 2040 Plan of the ICPR.
Final results expected around December 2021