SAR Imaging of Archaeological Sites on Intertidal Flats in the German Wadden Sea

Abstract

Abstract:We show that high-resolution space-borne synthetic aperture radar (SAR) imagery with pixel sizes smaller than 1 m 2 can be used to complement archaeological surveys on intertidal flats. After major storm surges in the 14th and 17th centuries ("Grote Mandrenke"), vast areas on the German North Sea coast were lost to the sea. Areas of settlements and historical farmland were buried under sediments for centuries, but when the surface layer is driven away under the action of wind, currents, and waves, they appear again on the Wadden Sea surface. However, frequent flooding and erosion of the intertidal flats make any archaeological monitoring a difficult task, so that remote sensing techniques appear to be an efficient and cost-effective instrument for any archaeological surveillance of that area. Space-borne SAR images clearly show remains of farmhouse foundations and of former systems of ditches, dating back to the times before the "Grote Mandrenke". In particular, the very high-resolution acquisition ("staring spotlight") mode of the TerraSAR/TanDEM-X satellites allows detecting various kinds of remains of historical land use at high precision. Moreover, SARs working at lower microwave frequencies (e.g., that on Radarsat-2) may complement archaeological surveys of historical cultural traces, some of which have been unknown so far.

Earth Observation, Remote Sensing and Geoscientific Ground Investigations for Archaeological and Heritage Research

“…Agapiou et al [8] 3278 1904 5 Agapiou et al [3] 1708 970 8 Chyla [9] 1429 827 1 Comer et al [5] 1570 1102 3 Corso et al [12] 1753 1215 2 Danti et al [10] 1943 1740 7 Drap et al [13] 1571 1565 2 Gade et al [6] 1751 1210 4 Garcia-Garcia et al [14] 1282 995 1 Guidi et al [15] 1719 976 3 Kalayci et al [16] 1218 968 2 Křivánek [17] 1420 1174 2 Malinverni et al [18] 1445 1345 1 Parcak et al [11] 1486 1374 3 Poux et al [19] 2306 2249 7 Rayne et al [7] 1750 1500 5 Rutishauser et al [4] 1784 1345 2 Sonnemann et al [20] 1582 1046 2 Tapete [1] 1256 2313 3 Traviglia & Torsello [2] 1680 1311 9 Verhoeven [21] 1573 1399 6 Building upon the positive outcome achieved in 2017 and in order to continue this Special Series, in March 2018 I launched the call for papers for a second edition of the Special Issue with the title "Earth Observation, Remote Sensing and Geoscientific Ground Investigations for Archaeological and Heritage Research".…”

Earth Observation, Remote Sensing, and Geoscientific Ground Investigations for Archaeological and Heritage Research

“…(1) broadened the spectrum of the topics to include Earth Observation (EO), to acknowledge that satellite imagery is nowadays regarded by the archaeological and heritage communities as a resource of spatial and temporal information (see the majority of the papers published in the first edition of the Special Issue: [3][4][5][6][7][8][9][10][11]);…”

Remote Sensing and Geosciences for Archaeology

“…Instead, the novelty nowadays lies in the use of new imaging modes (mostly from new or current space missions) and higher spatial resolution and more accurate derived products, as well as the development of methodologies integrating multi-source SAR data. It is with regard to these aspects that the papers published in the Special Issue [11,16,17] offer interesting evidence of scientific research achievements.…”

“…Gade et al [17] presents probably the first published example of the use of high-to very high-resolution SAR images acquired by the German Aerospace Center (DLR) constellation TerraSAR-X, including the Staring Spotlight mode, to detect and monitor the condition of lost coastal heritage in intertidal flats. The application on a constantly changing environment-where conditions of visibility of the archaeological remains and traces are discontinuous-proves how the tasking of satellite acquisitions is as important as the capability to extract features from the images after signal processing.…”

“…The papers published in the Special Issue cover a wide spectrum of techniques: satellite Synthetic Aperture Radar (SAR) imaging [11,16,17]; optical remote sensing from high to very-high resolution space-borne sensors [12,13,[18][19][20][21]; geophysics including magnetometer surveys, Ground Penetrating Radar (GPR), geoelectric resistivity measurements, multi frequency Electromagnetic Induction (EMI), piezoelectric/seismoelectric methods [9,22,23]; photogrammetry [24]; terrestrial laser scanning and three-dimensional (3D) point clouds [25,26]. Some of the papers also explore the benefits of combining different approaches, e.g., optical remote sensing, aerial imagery and geophysical prospection [27,28], 3D surveys, and reconstruction in GIS environment [29].…”