In the 2011 Great East Japan Earthquake and Tsunami Disaster, approximately 23 million tons of debris was estimated over wide areas caused by the tsunami damage. Quantitative estimation of tsunami debris is essential from disaster response point of view. In this study, a novel remote sensing method has been developed for measuring the amount of tsunami debris by integrating optical and LiDAR remote sensing. The analysis was conducted in Onagawa town, Miyagi Prefecture. Integration of horizontal mapping of tsunami debris and the analysis of digital surface model (DSM) of LiDAR data yields an estimate of the volume of tsunami debris.
Following the 2011 Great East Japan Earthquake Disaster, approximately 23 million tons of debris was generated and accumulated over wide areas because of the subsequent tsunami (Inui et al., 2012). Timely removal of the debris is an important and immediate issue for disaster recovery; therefore, accurate estimation of the quantity of debris is essential. Remote sensing technology is widely applied for the interpretation of wide disaster affected areas. In particular, optical sensor data and SAR (Synthetic Aperture Radar) data were often used for discriminating the tsunami inundation areas (Liu et al., 2013) and structural damage (Gokon et al., 2012; Gokon et al., 2015), and using SAR data provides good estimates of tsunami debris amounts (Koyama et al., 2016).
This study aims to develop a novel remote sensing method for directly measuring the amount of debris in the tsunami affected areas and for mapping the results. Specifically, two methods are integrated (Fig.1). The first extracts debris areas through image analysis of multi-temporal optical sensor data of aerial photos and satellite images obtained immediately after a disaster (Fig.2). The second determines its amount (volume, weight) by integrating the use of extracted debris area using optical sensors and the height of the debris obtained by air-borne LiDAR (Light Detection and Ranging).
