Use of Airborne Hyperspectral Data and Laserscan Data to Study Beach Morphodynamics along the Belgian Coast

• Published in: Journal of coastal research 2006-09, Vol.22 (5), p.1108-1117
• Main Authors: Deronde, Bart, Houthuys, Rik, Debruyn, Walter, Fransaer, Dirk, Lancker, Vera Van, Henriet, Jean-Pierre
• Format: Article
• Language: English
• Subjects: Applied geophysics; beach sand; Beaches; CASI; coastal accretion and erosion; Coastal plains; Coasts; Earth sciences; Earth, ocean, space; Exact sciences and technology; Grain size; image analysis; Imaging spectroscopy; Infrared reflection; integrated coastal zone management (ICZM); Internal geophysics; laserscanning; Marine; Marine and continental quaternary; Pixels; Remote sensing; Sand; Sedimentation; Sediments; Spectral reflectance; Studies; Surficial geology; Topsoil
• ISSN: 0749-0208; 1551-5036
• DOI: 10.2112/04-0264.1

This paper addresses the possibilities of the combined use of airborne hyperspectral data and airborne laserscanning data to study sand dynamics on the Belgian backshore and foreshore. In August 2000, August 2001, and October 2002, airborne hyperspectral imagery was acquired with a CASI-2 sensor from the entire Belgian beach at low tide. Hyperspectral images contain a reflectance spectrum for each pixel. The characteristics of this spectrum are influenced by the state, the composition, and the structure of the topsoil of the beach. After radiometric, geometric, and atmospheric correction of the images, a normalization of the spectral signatures was necessary to allow comparison of wet and dry pixels. Consequently, the first derivative of the normalized spectra was taken, followed by a spectral angle mapper algorithm that was used to perform a supervised classification. The beach was classified into eight sand classes. Almost simultaneous with the first two CASI campaigns (in September 2000 and September 2001), a laserscan survey was performed to generate digital terrain models with a mean vertical accuracy of 5 cm. By differencing both digital terrain models, a map with sedimentation and erosion zones could be extracted. The combined interpretation of the erosion/sedimentation map with the classified hyperspectral data yields an appropriate method for studying the processes of sand transport along the Belgian coastline. The method was tried out with success on the Belgian east coast.