Seminar Series

Spatiotemporal analysis on 3D morphology of coastal cliffs using TLS and SfM-MVS photogrammetry

Speaker

Yuichi Hayakawa

Institute

Faculty of Environmental Earth Science, Hokkaido University

Time & Place

Thu, 07 Nov 2019 11:00:53 NZDT in ER263

All are welcome

Abstract

Bedrock erosion of a small coastal island in the outer Boso Peninsula, named Suzume-Jima Island, is examined. Because this island is located outside of the artificial coastal protection, natural erosional processes can still be observed. Here we conducted repeated morphological measurements of the entire island using structure-from-motion multi-view stereo (SfM-MVS) photogrammetry based on an unmanned aerial system. We also carried out terrestrial laser scanning out for the accuracy assessment. The high-frequency (2 or 3 times a year) and high-resolution (at a centimetre scale) measurements of the small island for 5 years revealed spatially variable rockfalls and concentrated wave cuts. The volume of lost mass was quantified using the 3-D point cloud data series. The erosion rate of the bedrock cliffs is on the order of decimetres: this modern erosion rate is lower than the previously reported cliff retreat rates, suggesting that the small island will disappear in decades. Three-dimensional structural analysis will also help understand the dynamic processes of the erosion of the island.

Biography

Yuichi describes himself as a GIS Geomorphologist with research interests in landform evolution and geomorphological processes using Geospatial Information System (GIS), Global Navigation Satellite System (GNSS/GPS) surveying, airborne and terrestrial laser scanning (ALS and TLS), structure-from-motion multi-view stereo photogrammetry (SfM-MVS), and rock property measurements.