Monitoring annual changes of the coastal sedimentary budget in western Greece by terrestrial laser scanning

作者：Hoffmeister Dirk^*; Tilly Nora; Curdt Constanze; Ntageretzis Konstantin; Bareth Georg; Voett Andreas

来源：Zeitschrift fur Geomorphologie, 2013, 57: 47-67.

DOI：10.1127/0372-8854/2013/S-00139

• coastal monitoring
• sedimentary budget
• high-energy dislocated boulders
• terrestrial laser scanning
• tsunami wave transport equations
• coastal geomorphology

In this paper, we present annual changes of the sedimentary budget of seven selected sites on the Ionian Islands and the western Peloponnese (Greece), which were determined by annual terrestrial laser scanning (TLS) during the years 2009 to 2011. A Riegl LMS-Z420 i laser scanner was used in combination with a DGPS. In each study area, the base station of the DGPS was set up at the same marked position every year. The main objective of the study was to detect changes in the sedimentary budget of selected coastal sites that may occur from winter storms. At two study sites, high-energy dislocated boulders were additionally mapped and measured using the TLS method. Volume and mass data obtained for each dislocated boulder were used in tsunami wave transport equations in order to estimate minimum wave heights and wave velocities required for dislocation. These results were compared with maximum storm wave heights, measured by neighbouring buoys. %26lt;br%26gt;Generally, the method worked well, but difficulties occurred in areas with a high surface roughness resulting in occlusion phenomena in the point clouds. In addition, small deviations in the position and set-up of the laser scanner led to slight differences. However, all TLS data were visually controlled by means of the pictures of a digital camera mounted on top of the TLS system and by a direct point cloud comparison. %26lt;br%26gt;At two sites extensive changes in the littoral system were detected. These changes were due to the rearrangement of available sediment by littoral drift or smaller storm events. For all other sites, only minor, punctual changes were found. High-energy dislocated boulders showed no movement during the monitoring period. Thus, it is assumed that they were been transported inland by extreme events, which were stronger than the average coastal dynamics between 2009 and 2011. Both the orientation and the spatial distribution pattern of the dislocated boulders match with observations of boulders dislocated by tsunami impact. One smaller boulder encountered at the seaward edge of a boulder area seems to have been dislocated shortly before the monitoring campaign, presumably by strong winter storms during the 2008/2009 winter season.

• 出版日期2013-12