河川生息場の変動履歴分析のための河床地形モニタリング手法の開発

Abstract

Some recent studies highlighted dynamic nature of spatiotemporal patterns of riverine habitats. Existing habitat evaluation tools, however, lack this perspective. In order to analyze spatiotemporal patters that support biological diversity, we conducted a case study in a middle reach of the Tenryu River. Firstly, a set of interval-recording-cameras have been installed to monitor spatiotemporal changes caused by various flood events with different intensity and frequency. Secondly, we measured riverbed softness of habitat units, of which riffles are of particular importance for Ayu fish (Plecoglossus altivelis altivelis) as a spawning redd. Finally, we developed a monitoring method to analyze changing patterns of riverbed and riverine shifting habitat mosaic using a photogrametoric method. Habitat data recorded via several interval-recording-cameras were transformed into ortho data, and showed the effectiveness to analyze and quantify the spatiotemporal patterns.