17:15 〜 18:30
[HTT14-P01] Using remote sensing and GIS to track vegetation changes at Unzen Volcano, Kyushu, Japan
キーワード：Google Earth Engine, Remote sensing, Vegetation changes, GIS
Constraining the effects of vegetation on landform evolution is one of the biggest challenges in modern geomorphological studies. While there are many existing landform evolution models, not many studies have attempted to incorporate vegetation data explicitly due to difficulties in obtaining constructive quantitative data for integration into geomorphic transport functions. Quantification of the patterns and speeds of vegetation regrowth is integral to understanding the effects of vegetation on hillslope and other landform development. With time-robust remotely-sensed optical data and new platforms that allow for faster computation and processing, new opportunities to quantify vegetation changes at over larger areas and finer temporal scales are now available.
Using the study area of Unzen Volcano in Japan, this study aims to quantify vegetation regrowth on volcanic hillslopes. Unzen Volcano is the name of a cluster of volcanoes located on the Shimabara Peninsula in Nagasaki Prefecture, Kyushu. In its latest eruption sequence from 1991 – 1995, large pyroclastic flows emerged from Fugendake volcano, resulting in destruction of vegetation and infrastructure. Therefore, vegetation recovery from the period 1985 – 2011 was tracked over time. Satellite imagery from months June to August in the years of interest from the Landsat 5 Surface Reflectance Tier 1 dataset was processed in Google Earth Engine, and Normalized Difference Vegetation Index (NDVI) and fractional vegetation cover (FVC) time series analyses were performed with help of GIS.
Results from NDVI and FVC show that although all examined areas exhibited positive vegetation recovery rates, there are clear differences in vegetation recovery rate due to initial amount of damage and the location of vegetation. For areas in which vegetation returned to or close to pre-eruption levels, the rate of vegetation recovery was significantly quicker in the first five years of post-eruption.
Using the study area of Unzen Volcano in Japan, this study aims to quantify vegetation regrowth on volcanic hillslopes. Unzen Volcano is the name of a cluster of volcanoes located on the Shimabara Peninsula in Nagasaki Prefecture, Kyushu. In its latest eruption sequence from 1991 – 1995, large pyroclastic flows emerged from Fugendake volcano, resulting in destruction of vegetation and infrastructure. Therefore, vegetation recovery from the period 1985 – 2011 was tracked over time. Satellite imagery from months June to August in the years of interest from the Landsat 5 Surface Reflectance Tier 1 dataset was processed in Google Earth Engine, and Normalized Difference Vegetation Index (NDVI) and fractional vegetation cover (FVC) time series analyses were performed with help of GIS.
Results from NDVI and FVC show that although all examined areas exhibited positive vegetation recovery rates, there are clear differences in vegetation recovery rate due to initial amount of damage and the location of vegetation. For areas in which vegetation returned to or close to pre-eruption levels, the rate of vegetation recovery was significantly quicker in the first five years of post-eruption.