RELATIONSHIP BETWEEN RIVER REGIME AND FISH HABITAT BASED ON THE DATA OF THE NATIONAL SURVEY FOR RIVER AND RIPARIAN ENVIRONMENT: USE OF AN INDICATOR OF FLUVIAL BAR FORMATION

Abstract

To clarify whether the regime criteria on formation of fluvial bars in alluvial straight channels characterizes habitat features of Japanese dace (Tribolodon hakonensis), the relationship between BI0.2/H (B: channel width, I: slope, H: depth) and the fish population was analyzed. Numerical calculations using iRIC software generated habitat velocity and depth during normal flow for PHABSIM. Japanese dace population of each site was taken from the dataset of the national survey for river and riparian environment, conducted in the Ishikari River and its branch streams. Our results show that the peak of fish population occurred in the BI^0.2/H range between 15 and 25. The result of PHABSIM also indicated that the rivers with BI^0.2/H between 15 and 25 provide suitable environment for juvenile dace. These results suggest that BI^0.2/H is a useful indicator for the quality of fish habitat.