TRANSPORT MECHANISM IN TIDAL DUNES

Horst Nasner

Abstract


An interesting question arising within the scope of the further development of the German tidal rivers Elbe and Weser, is whether tidal dunes or sand waves will be formed after the navigation channel deepenings and that the success of the development measures will thus be partially or fully undone. In order to be able to better assess the formation and regeneration of these large patterns after dredging, heightened knowledge of the sand transport in a tidal dune field is necessary. A possibility of investigating the sand transport in a tidal river with pronounced tidal dunes in the field, can be realized by measurings with luminaries or tracers. The advantage of investigations in the field is, that all laboratory required scale effects are eliminated. The more difficult measuring comprehension of the course of the test in prototype must be solved through purposefully planned investigation programs. Subsequent to observations of many years standing, on behavior of four tidal dune areas in the navigation channel of the Weser River estuary (6), investigations were carried out with luminaries above reach 1 (Fig. 1) from September till November 1974. The aim was, to obtain information on the transport mechanism for tidal dunes and heightened knowledge on the causes of regeneration after dredging.

Keywords


tidal dune; transport; transport mechanism

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