Investigating Changes in Aeolian Sediment Transport at Coastal Dunes and Sand Trapping Fences: A Field Study on the German Coast

Christiane Eichmanns,Holger Schüttrumpf

doi:10.3390/jmse8121012

Christiane Eichmanns, Holger Schüttrumpf

Open Access

https://doi.org/10.3390/jmse8121012

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Abstract

For the restoration and maintenance of beach and dune systems along the coast, knowledge of aeolian sediment transport and its interaction with coastal protection measures is required. As a nature-based solution, sand trapping fences can be an integral part of coastal protection measures initiating foredune development. There are few detailed studies on aeolian sediment transport rates on coastal dunes and sand trapping fences available to date. Thus, in this work, we present the results of field experiments conducted at the beach, coastal dune, and sand trapping fence on the East Frisian island Langeoog. The vertical sediment flux profile was measured by vertical mesh sand traps, and saltiphones measured the instantaneous sediment transport. A meteorological station was set up to obtain wind data. On the beach, dune toe, and dune crest, the stationary wind profile can be described well by the law of the wall. Saturated aeolian sediment transport rates on the beach and dune toe were predicted by widely used empirical models. Between the sand trapping fence, these empirical transport models could not be applied, as no logarithmic wind profile existed. The upwind sediment supply reduced after each brushwood line of the sand trapping fence, thereby, leading to increased deviation from the saturated conditions.

Highlights

Coastal protection measures on the East Frisian Islands in the German North Sea generally involve coastal dunes, coastal dikes, and associated coastal protection structures [1,2]
According to the conducted sieve analyses, the median grain size D50 ~218 μm was chosen as an average value for the measurement locations of the beach, dune toe, and sand trapping fence
This work presents the results of field experiments conducted on the coast of the East Frisian island Langeoog, analyzing wind and sediment transport data at the beach, coastal dune, and sand trapping fence

Summary

Introduction

Coastal protection measures on the East Frisian Islands in the German North Sea generally involve coastal dunes, coastal dikes, and associated coastal protection structures [1,2]. The main roles of the coastal dunes on the East Frisian Islands are to provide flood protection for flood-risk areas against storm surges and to secure the existence of these islands [2,3,4,5]. These islands form a natural barrier system that reduces the wave energy during storm surges on the mainland coast in Lower Saxony. The planting of vegetation and installing sand trapping fences to stabilize the natural dynamics of the dune system represent an additional component of coastal protection on the East Frisian Islands [8]

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