This paper deals with the hydraulic and hydrologic properties of the habitat of fish in a river and surrounding area. It especially focuses on the habitat of the Acheilognathus Longipinnis in the lower reach of the Yodo River, because the restoration of its habitat is the most important and urgent work for the Yodo River eco-system. The estimation of flood disturbance required for the life history of the fish was examined in the Akagawa sand bar and Shirokita Embayments, where both areas were its most important habitat 40 years ago, through the return period of the magnitude of the flood discharge, the frequency of the water surface elevation, which were obtained by the statistics of the water surface elevation records, and the magnitude of the order of the velocity and the shear velocity and their distributions, which were obtained through the 2-D numerical simulation. The results will be usable for the selection of the location of the newly constructed habitat, and its design.
