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| Lurton, Xavier; Eleftherakis, Dimitrios; Augustin, Jean-marie. |
| The sediment backscatter strength measured by multibeam echosounders is a key feature for seafloor mapping either qualitative (image mosaics) or quantitative (extraction of classifying features). An important phenomenon, often underestimated, is the dependence of the backscatter level on the azimuth angle imposed by the survey line directions: strong level differences at varying azimuth can be observed in case of organized roughness of the seabed, usually caused by tide currents over sandy sediments. This paper presents a number of experimental results obtained from shallow-water cruises using a 300-kHz multibeam echosounder and specially dedicated to the study of this azimuthal effect, with a specific configuration of the survey strategy involving a... |
| Tipo: Text |
Palavras-chave: Azimuth dependence; Seafloor backscatter; Multibeam echosounder; Sand ripples. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00386/49782/50326.pdf |
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| Montereale-gavazzi, Giacomo; Roche, Marc; Lurton, Xavier; Degrendele, Koen; Terseleer, Nathan; Van Lancker, Vera. |
| To characterize seafloor substrate type, seabed mapping and particularly multibeam echosounding are increasingly used. Yet, the utilisation of repetitive MBES-borne backscatter surveys to monitor the environmental status of the seafloor remains limited. Often methodological frameworks are missing, and should comprise of a suite of change detection procedures, similarly to those developed in the terrestrial sciences. In this study, pre-, ensemble and post-classification approaches were tested on an eight km2 study site within a Habitat Directive Area in the Belgian part of the North Sea. In this area, gravel beds with epifaunal assemblages were observed. Flourishing of the fauna is constrained by overtopping with sand or increased turbidity levels, which... |
| Tipo: Text |
Palavras-chave: Multibeam; Seafloor backscatter; Change detection; Seafloor integrity; Marine Strategy Framework Directive; Reference calibration area. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00387/49807/50379.pdf |
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