Yoshitaka Fukui

A STUDY ON ISSUES AND COPING METHODS IN THE POOL-AND-WEIR-FISHWAY WITH PRIMING WATER

Through the ages, the pool-and-weir-fishway have been installed in many rivers in Japan. As time advances, fish-ways fail to function adequately because they are deteriorated, broken or changed flow in the downstream. The main purpose of this study is to make clear the problems of fish-ways and to find better resolution methods to solve it. Therefore, we carried out the model experiment by using the open channel where a pool-and-weir-fish way had been set up. As a result, a promising method to cope with the local scouring and circulation flow at the downstream of fish-way is studied by the model experiment.

HYDRAULIC FUNCTIONS OF THE PILE DIKE AND ITS IMPACT ON FISH BEHAVIOR IN THE VICINITY

This research consists of three parts. First is the study about the flow influenced by the pile dike in the river. Second is an examination of whether regions in pile dikes are suitable as a habitat for fish. Third is a numerical analysis concerning the relationship between the flow and the behavior of fish. To complete the first part, velocity of flow and water depth in an open channel is measured. In the second part, fresh water fish (Tribolodon hakonensis) are released into the flow and their behavior is observed by video camera. Finally, the two-dimensional shallow water equation is used to examine the profile of the flow. The random walk method is adopted to examine the behavior of fish in the flow. The flow and the behavior of fish in the channel become clean through our experiment and numerical analysis.

FLOW OVER THE SQUARE ARTIFICIAL ROUGHNESS SET OBLIQUELY ON THE BED OF AN OPEN CHANNEL

The paper is written about the flow behavior over the square roughness, which are set obliquely on a bed of an open-channel. In the experiment, a single and more square roughness is set obliquely on the bed, and the ratio of the water depth to roughness height and the length of roughness are changed. The aim of this study is to investigate an existence of the spiral flow. By using such spiral flow, sediment load and floating material in the flow may be sent to the downward of channel. In the case using long roughness, the existence of spiral flow is recognized clearly but for the case shorter roughness, in such case between a pointed end of roughness and right side wall, there is no obstacle, such spiral flow can not be recognized so clearly. And in such shorter case, strong secondary flow from left side to right side along the bed is not produced.