Author(s): Silke Wieprecht
Linked Author(s): Silke Wieprecht
Keywords: Sedimentation in reservoirs; Flushing; Suspended Material; HCB
Abstract: This paper analyzes the situation at the Iffezheim barrage along the river Rhine. Since the start of operation in 1977 several million cubic meters of very fine sediment have been deposited in the reservoir. Because of stability problems and reduced safety in the event of flooding, an extraction of the material is necessary. Chemical assays showed a high concentration of HCB. Therefore flushing without any additional measures is not appropriate. In order to learn more about the morphological and chemical interactions during the dredging and flushing of fine sediments, two tests were carried out. Numerous measurements and samples were taken and analyzed. The main part of the sediment remains in suspension in the first part of the investigated river section only. Approximately sixty-five percent of the dredged material deposits itself within the first three kilometers of the flow path. The remaining sediment stays in suspension. With regards to the HCB concentration, it could be shown that the substance is not only agglutinated on the finest particles, but rather that the noxious substances are connected to the coarser material as well. Further study must be carried out.