Optimizing the hydraulic-morphological situation between Iffezheim and Mainz
On behalf of the WSD Southwest, the BAW and BfG are working together to draw up an optimization strategy regarding the interaction of river control and bed load management for the stretch between Iffezheim and Mainz.
Sediment transport models are geared to optimizing measures for the control and maintenance of the federal waterways. This consists in carrying out corresponding analysis with a 1D sediment transport model for the section of the river Rhine between Iffezheim (km 334.00) and Mainz (km 498.30). Furthermore, 2D morphodynamic simulations are carried out between Iffezheim and Speyer (km 394.3). This two-dimensional model encompasses measures for both bed load management and river control with their resolution in both time and space, thus making it possible to optimize the maintenance strategies on the basis of their hydromorphological effects.
Another major step towards a better understanding particularly of the morphodynamic processes in the section of the river Rhine between Iffezheim and Mainz consists of analysing and evaluating the actual condition of this stretch of the river, investigating the efficacy of the control system. At the moment, work is concentrating on problem-oriented preparation, evaluation and interpretation of existing data, as well as identifying the causal relationships.
Analysing the actual condition also includes reviewing navigability with an indication of traffic bottlenecks. To this end, two test journeys were carried out with large motorized freight vessels and pushed barge units under bottleneck conditions. Subsequent evaluation focused on the course axes, vessel speeds, required traffic space and the necessary safety clearances, together with an analysis of the additional width resulting from transverse offset and Z-manoeuvres. These tests show that more than twice the additional width has to be calculated than is the case in other waters, apparently as a consequence of the strict groyne control. These data can be used to calculate the locally necessary minimum fairway width, for defining the maximum permissible reach of the groynes, among others. The tests also serve to verify the models for evaluating the dynamic traffic aspects of the upgrading situation.
The recommendations for adapting the control system and for future maintenance practice are being elaborated jointly by the BAW and BfG, taking account of all study contents.
WSA Freiburg: Geschiebezugabe unterhalb Iffezheim, Situationsbericht, as of January 1998
BAW: Bericht zur Bewertung der Strecke UW Iffezheim auf der Grundlage einer Literaturrecherche zur Situation im Unterwasser der Staustufe Iffezheim. Karlsruhe, June 2006
BAW: Abschlussbericht zum physikalischen Modell Iffezheim. Karlsruhe, June 2008
BAW: Historische Entwicklung des Regelungssystems zwischen Iffezheim und Mainz. Draft, Karlsruhe, August 2008
One-dimensional sediment transport model (FTM)