ハビタットアセスメントにおける河道内微地形の把握手法に関する研究

抄録

Channel Geomorphic Units (CGUs) are fundamental factors to determine habitat structures in a lotic zone. In midstream segment, CGUs and habitat types has been recognized by their scenery, however the method is not able to be applied into quantitative habitat assessment owing that it is based on human sense. In this research, a new approach will be provided to recognize the each CGU and a habitat type corresponding to the each CGU by measuring longitudinal profiles for a water surface and a stream bed along a thawleg. A boundary between two CGUs is indicated by a breaking point of the water surface, and the habitat type is determined by the range of the water surface slope, relative height of the downstream edge of the each CGU to the upstream edge. Furthermore the longitudinal ratio of water surface widths has a unique character to recognize a threshold between riffles, and pools and glides.