DEVELOPMENT OF BASIC INFORMATION ON THE GROWTH OF VEGETATION IN RIVER CHANNELS USING SATELLITE IMAGES ACROSS JAPAN

Abstract

 The objective of this study was to establish basic information on vegetation growth in the river channel. Specifically, the vegetation in the river channel was classified based on the Normalized Difference Vegetation Index (NDVI) calculated from satellite images and the average annual change in NDVI. Differences in classification were also examined by first-class water systems and upstream and downstream. The results showed that the vegetation growing in the river channels of first-class water systems throughout Japan was generally herbaceous. The NDVI tended to increase in the upstream and downstream areas, mainly in eastern Japan, and there were many forested areas with positive values of NDVI change. In western Japan, however, there was a trend toward more herbaceous species with positive NDVI change and fewer forested areas with positive NDVI change. In addition, differences in herbaceous species growth were observed by first-class water systems upstream and downstream. The basic information developed in this study is expected to contribute to effective river channel management planning for flood damage reduction and global warming mitigation.