Multi-Coil FD-EMI in Tidal Flat Areas: Prospection and Ground Truthing at a 17th Century Wooden Ship Wreckage

Dennis Wilken,Dirk Bienen-Scholt,Ercan Erkul,Simon Fischer,Daniel Zwick,Bente Sven Majchczack,Ruth Blankenfeldt

doi:10.3390/rs14030489

Dennis Wilken, Dirk Bienen-Scholt + Show 5 more

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https://doi.org/10.3390/rs14030489

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Abstract

We present a case study of multi-coil frequency-domain electromagnetic (FD-EMI) prospection of a wooden ship wreckage from the 17th century. The wreckage is buried in a sandbar in the German part of the tidal flat area of the North Sea. Furthermore, the wreckage was excavated in advance and covered again after investigation. This ground truthing background and the position of the wreckage makes it a unique investigation object to test the feasibility of FD-EMI for prospecting wooden archaeological objects in the high conductive sediments of tidal flat areas. Our results reveal the shape and position of the wreckage in terms of conductivity maps. The resulting signal change caused by the wreckage in conductivity is only 10% of the value of the water-saturated sandy background, respectively, making a cautious process necessary, including a precise height correction. The data, furthermore, reveals a sensitivity to the vertical shape of the wreckage and thus sufficient depth sensitivity, but with reduced sensing depth. The study highlights the great potential of EMI for both in situ heritage management and archaeological research in the Wadden Sea.

Highlights

The Wadden region along the North Sea coast is an area of dyked or formerly dyked salt marshes and reclaimed coastal peat bogs [1]
In this work we aimed to test the applicability of frequency-domain-electromagnetic induction (EMI) to the prospec3 of 12 tion of wooden archaeological targets in the difficult environment of tidal flats
What are the difficulties for EMI when dealing with seawater environments and The test site was chosen at a silted, articulated slab of planking measuring about how can we address them?

Summary

Introduction

The Wadden region along the North Sea coast is an area of dyked or formerly dyked salt marshes and reclaimed coastal peat bogs [1] This coastal wetland contains visible, past human adaptations to the environment in the form of embankments, dykes, canals, and polders, making it a cultural landscape of exceptional cultural, historical value ([1,2]). Natural and human-influenced dynamics have changed the marshes and tidal flats throughout time These changes are especially visible by the numerous traces of medieval and post-medieval settlements and remains of their cultural landscapes that appear and disappear in the ever-changing environment of the Wadden Sea. Usually, archaeological site investigation in the tidal flat region of Germany has been performed using boreholes, trenches, surface findings, and (aerial) photographs.

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