Mapping the restoration process of coastal forests damaged by the 2011 tsunami using NDVI and LAI from time-series high-resolution satellite data

Abstract. Approximately 14 years have passed since the large-scale Great East Japan Earthquake that occurred in the Tohoku region of Japan. For coastal disaster prevention, coastal forests, mainly consisting of black pine trees, had been developed over a wide area before the earthquake and were maintained by the Forestry Agency and local governments. The huge tsunami caused severe damage to these coastal forests, including fallen and lost trees. In order to progress in the restoration of coastal forests, it is necessary to effectively map the process over time. In this study, by using time-series high-resolution satellite remote sensing by Worldview-2,3 and GeoEye-1, the time-series changes in the afforestation area over a long period of approximately 12 years from before the disaster to immediately after the disaster and thereafter were mapped in detail by interpretation survey of high-resolution satellite images and analysis of the normalized difference vegetation index (NDVI). Furthermore, by using the conversion formula from NDVI to the leaf area index (LAI) reported in previous studies, an attempt was made to evaluate the restoration process of coastal forests from the disaster using LAI mapping. As a result, the process of restoration of coastal forests from the tsunami damage was effectively demonstrated through image interpretation and the characteristics of the spatial distribution of both index values.