SAND MOVEMENT INVESTIGATIONS BY MEANS OF RADIOACTIVE TRACERS IN A HYDRAULIC MODEL AND IN THE FIELD

Abstract

The Lower and the Outer Elbe constitute the sea-going navigation channel which has the heaviest shipping traffic in the Federal Republic of Germany. In order to obtain and maintain the fairway depth necessary for shipping, river construction works and dredging are applied to an equal extent (5). In order to investigate the practicability of these measures in detail, large hydraulic models of the River Elbe Estuary are available at the Coastal Department of the Federal Institute for Hydraulic Engineering (AuBenstelle Kiiste der Bundesanstalt fur Wasserbau) at Hamburg. The problems which result from the displacement of the sands and the fairways, as well as those of sediment transportation, are especially investigated in a model with a moveable bed consisting of granulated polystyrol (5)» Details concerning the construction, instrumentation, and questions concerning the scale ratios of this model were given by VOLLMERS during the 13th International Conference on Coastal Engineering 1972 in Vancouver (7). Fig. 1 shows the River Elbe Estuary and the outer boundaries of the model, the length scale of which is 1 : 8oo and the depth scale 1 : loo. Fig. 2 shows a view of the model in the direction of the ebb current.