For the evaluation of habitat suitability for fish, hydraulic data that can be easily observed have been often used. However, it has become essential to consider fish's preference for riverbed environments modified by artificial sediment supply in gravel-bed rivers. In this study, two types of evaluation methods were applied on the target river with different riverbed environment in the two diversion channels. These models are conventional evaluation method based on hydraulic quantity (HSI), and it taking into account the sand cover on stony riverbed as a riverbed environment in addition to the hydraulic quantity (HSIb). The prediction accuracy was elucidated by comparing the habitat suitability index calculated from these models with the spatial distribution of the focal point of Ayu obtained from the field survey. The evaluation of habitat suitability taking into account the degree of sand coverage (HSIb) was found to be able to evaluate the focal point of Ayu more accurately than the conventional method (HSI).
