Search publications of the members of the Royal Belgian institute of natural Sciences
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Digital mapping of coastal boulders – high-resolution data acquisition to infer past and recent transport dynamics
- Coastal boulder fields provide clues to long-term frequency-magnitude patterns of coastal flooding events and have the potential to play an important role in coastal hazard assessment. Mapping boulders in the field is time and labour-intensive, and work on intertidal reef platforms, as in the present study, is physically challenging. By addressing coastal scientists not specialized in remote sensing, this contribution reports on the possibilities and limitations of digital applications in boulder mapping in Eastern Samar, Philippines, where recent supertyphoons Haiyan and Hagupit induced high waves, coastal flooding and boulder transport. It is demonstrated how satellite imagery of submetre resolution (Pléiades, WorldView-3) enables efficient analysis of transport vectors and distances of larger boulders, reflecting variation in latitudes of both typhoon tracks and approaching angles of typhoon-generated waves. During the investigated events, boulders with a-axes of up to 8 m were clearly identified to have been shifted for up to 32 m, mostly along the seaward margin of the boulder field. It is, however, hard to keep track of smaller boulders, and the length of a-axes and b-axes including their orientation is often impossible to map with sufficient accuracy. Orthophotographs and digital surface models created through the application of an unmanned aerial vehicle and the ‘Structure from Motion’ technique provide ultrahigh-resolution data, and have the potential to not only improve the results of satellite image analysis, but also from field mapping and may significantly reduce overall time in the field. Orthophotographs permit unequivocal mapping of a- and b-axes including their orientation, while precise values for c-axes can be derived from the respective digital surface models. Volume of boulders is best inferred from boulder-specific Structure from Motion-based three-dimensional models. Battery power, flight speed, and altitude determine the limits of the area covered, while patches shielded by the boulders are difficult to resolve. For some tasks field mapping remains mandatory and cannot be replaced by currently available remote sensing tools: for example, sampling for rock type, density and age dating,recording of lithological separation of boulders from the underlying geological unit and of geomorphic features on a millimetre to decimetre-scale, or documentation of fine-grained sediment transport in between the boulders in supratidal settings. In terms of future events, the digital products presented here will provide a valuable reference to track boulder transport on a centimetre to decimetre-scale and to better understand the hydrodynamics of extreme-wave events on a fringing reef coastline.
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Long-term trends of land use and demography in Greece: a comparative study
- This paper offers a comparative study of land use and demographic development in northern and southern Greece from the Neolithic to the Byzantine period. Results from summed probability densities (SPD) of archaeological radiocarbon dates and settlement numbers derived from archaeological site surveys are combined with results from cluster-based analysis of published pollen core assemblages to offer an integrated view of human pressure on the Greek landscape through time. We demonstrate that SPD can be a useful approach to outline differences between regions and a useful complement to archaeological site records, evaluated here especially for the onset of the Neolithic and the Final Neolithic/Early Bronze Age transition. Pollen analysis highlight differences in vegetation between the two subregions but also several parallel changes. The comparison of land cover changes between two sub-regions of Greece further demonstrate the significance of the bioclimatic conditions of core locations and that apparent oppositions between regions may in fact be two sides of the same coin in terms of socio-ecological trajectories. We also assess the balance between anthropogenic and climate related impacts on vegetation and suggest that climatic variability was as an important factor for vegetation regrowth. Finally, our evidence suggest that the impact of humans on land cover is amplified from the Late Bronze Age onwards as more extensive herding and agricultural practices are introduced.
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Description of Chicoreus (Triplex) franzettiae n. sp. (Gastropoda: Muricidae) from the Philippine Islands
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A little-known German naturalist: Konrad Miller (1844-1933) and his malacological contributions
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A review of Stenostylus Pilsbry, 1898 and Drymaeus Albers, 1850 (Mollusca: Gastropoda: Orthalicoidea: Bulimulidae) from Colombia, with description of new species
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Reconstructing science networks from the past: eponyms between malacological authors in the mid-19th century
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Charles Hippolyte Crosse (1826-1898) and his contributions to malacology: a biography and bibliography
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Obsessed with shells: John L. Staid-Staadt (1886-1969) as a life-long and ardent collector
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Enkele onbekende Nederlandse schelpenverzamelingen uit de 19e eeuw
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A candid view of relations between malacologists in the second half of the nineteenth century: the correspondence of Henri Drouët with Hippolyte Crosse
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Bridging the Atlantic: the correspondence of Thomas Bland and William Binney with Hippolyte Crosse, between 1863 and 1885
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Notes on Drymaeus species from Peru (Mollusca, Gastropoda, Bulimulidae), and description of a new species
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Herman Roeters van Lennep (1820-1879) and the auction of his collection.
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More than just a name: Colonel Messager and his correspondents
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Faunal report. In: Jimenez Serrano, A. et al. Proyecto Qubbet el-Hawa: Trabajos arqueólogicos en las tumbas QH32, QH33, QH34aa, QH34bb, QH122, QH35p y QH36. Novena Campaña (2017)
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Indice de minéralisation sulfurée (Fe, Zn, Pb, Cu, Ni, Co) liée aux strates du Frasnien (limite F2-F3) dans le sondage d'Heibaart (Loenhout, province d'Anvers).
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La définition du synclinorium de Verviers
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Comments on the paper by Préat et al. (1983) : Caractères Epigénétique - Etranger des Gîtes Filoniens Pb-Zn (Ba-F) du Bord Sud du synclinorium de Dinant (Belgique)
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Le gîte de barytine de Chaudfontaine. In : Métallogénie de la Belgique, des Pays-Bas et du Luxembourg. Mémoire explicatif de la Carte métallogénique de l'Europe et des pays limitrophes.
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Les gisements de fer du Benelux
