Abstract
In this study, we propose a method to monitor vegetation in Japanese rivers using a synthetic aperture radar (SAR) satellite. The proposed method was applied to the Sabagawa River in Yamaguchi Prefecture, Japan. We compared a combined X and L band SAR image with a survey result obtained by drone aerial shooting. While we observed shadow areas behind a bamboo grove in the river on the line-of-sight of the satellite in the X band SAR image, any distinctive shadow area of the bamboo grove was not observed in the L band SAR image. Extracting shadow areas that appeared only in X band SAR image, we found that the extracted area were observed behind the bamboo grove area. Based on the observation principle of SAR satellite, we proposed an equation to estimate a bamboo height from a shadow area on a combined X and L band SAR image. The proposed equation reproduced the bamboo heights from the shadow areas on the SAR image accurately. The mean and standard deviation of relative errors were -15.6% and 17.0%, respectively.
