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Browsing by Author "Alves, Bruna"

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  • Deriving high spatial-resolution coastal topography from sub-meter satellite stereo imagery
    Publication . Almeida, Luís Pedro; Almar, Rafael; Bergsma, Erwin; Berthier, Etienne; Baptista, Paulo; Garel, Erwan; Dada, Olusegun; Alves, Bruna
    High spatial resolution coastal Digital Elevation Models (DEMs) are crucial to assess coastal vulnerability and hazards such as beach erosion, sedimentation, or inundation due to storm surges and sea level rise. This paper explores the possibility to use high spatial-resolution Pleiades (pixel size = 0.7 m) stereoscopic satellite imagery to retrieve a DEM on sandy coastline. A 40-km coastal stretch in the Southwest of France was selected as a pilot-site to compare topographic measurements obtained from Pleiades satellite imagery, Real Time Kinematic GPS (RTK-GPS) and airborne Light Detection and Ranging System (LiDAR). The derived 2-m Pleiades DEM shows an overall good agreement with concurrent methods (RTK-GPS and LiDAR; correlation coefficient of 0.9), with a vertical Root Mean Squared Error (RMS error) that ranges from 0.35 to 0.48 m, after absolute coregistration to the LiDAR dataset. The largest errors (RMS error > 0.5 m) occurred in the steep dune faces, particularly at shadowed areas. This work shows that DEMs derived from sub-meter satellite imagery capture local morphological features (e.g., berm or dune shape) on a sandy beach, over a large spatial domain.
    2019Journal article Open access Show more
  • How feasible is coastal management? A social benefit analysis of a coastal destination in SW Spain
    Publication . Alves, Bruna; Ballester, Ramon; Riga-I-Torrent, Ricard; Ferreira, Oscar; Benavente, Javier
    Very few assessments of the beach recreational experience value have been made in Spain. This is both surprising and discouraging considering the importance of sun-and-sand tourism to the country. The present study applies the Travel Cost Method (TCM) to assess the non-market user value of three Atlantic beaches in southern Spain. The results reveal that there are statistically significant differences in visitor type by season and by beach. Calculations show that the socioeconomic benefits generated by one hectare of any of the studied beaches during the high season are one order of magnitude greater than the average annual amount of capital invested in coastal management projects and actions. It is apparent that expenditure on management strategies for the beaches of Cadiz is justified. Policy-makers should recognise that the consumer surplus is an important component of economic value because it represents a measure of social benefits rather than on-site expenditures alone. (C) 2016 Elsevier Ltd. All rights reserved.
    2017-06Journal article Restricted access Show more