Characterisation of Coastal Sediment Properties from Spectral Reflectance Data

Abstract

Remote sensing of coastal sediments for the purpose of automated mapping of their physical properties (grain size, mineralogy and carbonate content) across space has not been widely applied globally or in South Africa. This paper describes a baseline study towards achieving this aim by examining the spectral reflectance signatures of field sediment samples from a beach–dune system at Oyster Bay, Eastern Cape, South Africa. Laboratory measurements of grain size and carbonate content of field samples (n = 134) were compared to laboratory measurements of the spectral signature of these samples using an analytical spectral device (ASD), and the results interrogated using different statistical methods. These results show that the proportion of fine sand, CaCO3 content and the distributional range of sediment grain sizes within a sample (here termed span) are the parameters with greatest statistical significance—and thus greatest potential interpretive value—with respect to their spectral signatures measured by the ASD. These parameters are also statistically associated with specific wavebands in the visible and near infrared, and the shortwave infrared parts of the spectrum. These results show the potential of spectral reflectance data for discriminating elements of grain size properties of coastal sediments, and thus can provide the baseline towards achieving automated spatial mapping of sediment properties across coastal beach–dune environments using hyperspectral remote sensing techniques.

Sandy Beach Mapping using a Deep Learning Approach: Potential Method for Automated Monitoring of Algerian Coastal Erosion

“…Few academic studies focus on the combination with Hyperspectral or Lidar sensors to minimize radiometric confusion (Deronde et al ., 2008), or even radar data (Valle et al ., 2010) for the specificity of sand dunes’ wavy shape. Other studies concentrated on physical/chemical characteristics of sand grain (Kerosky and Chaussard, 2016; Knight and Abd Elbasit, 2022), or even using airborne spectrometer (Kaiser, Aziz, and Ghieth, 2014); however, all those approaches had as the principal aim either shoreline dynamics (line of contact water-land) or sand grain characteristics. It is also remarkable that the majority are applied on small geographic scales (local scale “one or few beaches”) and unfortunately are not reproducible on a large scale (Algerian national scale).…”