Abstract
Abstract. Due to both natural and anthropogenic causes, the coastal lines keeps changing dynamically and continuously their shape, position and extend over time. In this paper we propose an approach to derive a tide-coordinate shoreline from two extracted instantaneous shorelines corresponding to a nearly low tide and high tide events. First, all the multispectral images are panshaperned to meet the 15 meters spatial resolution of the panchromatic images. Second, by using the Modification of Normalized Difference Water Index (MNDWI) and the kmeans clustering method we extract the raster shoreline for each image acquisition time. Third, each raster shoreline is smoothed and vectorized using a penalized least square method. Fourth, a 2D constrained Delaunay triangulation is built from the two extracted instantaneous shorelines with their respective heights interpolated from a Tidal gauche station. Finally, the desired tide-coordinate shoreline is interpolated from the previous triangular intertidal surface. The results show that an automatic tide-coordinated extraction method can be efficiently implemented using free available remote sensing imagery data (Landsat 8) and open source software (QGIS and Orfeo toolbox) and python scripting for task automation and software integration.
Highlights
Coastal zones are one of the most dynamic environments on Earth’s surface
In this paper we propose a novel approach to derive a tide-coordinate shoreline from two extracted instantaneous shorelines correspondent to a nearly low tide and high tide events
We observe that the extraction process based on the Modification of Normalized Difference Water Index (MNDWI) index is insensitive to the foam of the ocean waves
Summary
Coastal zones are one of the most dynamic environments on Earth’s surface. They are defined by International Geosphere Biosphere Programme (IGBP) as the zones delimited inferiorly by the 200m bathymetric contour and superiorly by 200m topographic contour. Shorelines can be considered one of the most important Earth’s terrain features, as 84% of the countries in the world have shorelines adjacent to open oceans, inland seas or both (Martnez et al, 2007). Due to both natural and anthropogenic causes, the shoreline keeps changing dynamically and continuously their shape, position and extend over time (Boak and Turner, 2005). Because of the dynamic nature of the ocean waters and of the near coastal lands we need to introduce the definiton of instantaneous shoreline to point out that line position is relative to a given instant of time (Li et al, 2002). If this vertical datum is defined as the linear intersection between the coastal surface and a desired water tidal level, the shoreline is called tide-coordinated shoreline (Li et al, 2002)
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