Author(s): Morihiro Harada, Rahma Yanda, Yukio Onoda, Yuichi Kayaba
Linked Author(s): Morihiro Harada
Keywords: Habitat evaluation procedure (HEP), water-column fish, flume experiment, velocity profile, roughness layer.
Abstract: In this paper, a method of habitat evaluation for water-column fish is proposed that focuses on the velocity profile, which is spatially heterogeneous in the roughness layer. Experimental testing is conducted using three different methods to evaluate the habitat volume of swimming fish within the velocity profiles of four different bed conditions. In order to investigate the flow characteristics of the boulder-bed, the first set of experiments was performed within a large flume. After the velocity conditions are confirmed, the activity of living, swimming fish is observed under those conditions for the second set of experiments. Opsariichthys platypus (Zacco platypus), which is a dominant fish species among Japanese freshwater fish, is used for the living fish experiment. Based on the results of the two experiments, the accuracy of the three methods is analyzed. The first method uses a depth-averaged velocity, the second method uses a velocity profile averaged in the same depth of each of the vertical transects and porosity profile of the bed, and the third method uses the velocity profiles from each of the vertical transects. The second method is found to be the most effective in providing a quantitative estimation for fish habitats with changes in river bed conditions if the averaged velocity profiles are known or predicted by another model, such as the double-averaging method (DAM)
Year: 2017