Development of a new fishway for various fish species and cost reduction

201-20

Flow Characteristics Near the Outlet of a Fishway with Headworks

In this research, we studied the optimum positions of fishways through a few inquiries into existing fishways and related positive investigation. Then, we made a laboratory reproduction of data concerning the shape of channels near headworks. In Japan, these are widened so as not to impede the descent of flood flow. We also checked for the characteristics of the compound cross-section channel, which is locally strongly affected by the widened part, as a structure necessary to assure a gut and grasped its basic flow regime pattern

Problems with a Fishway on an Irrigation Barge in Japan

In this paper, we discussed about problems of fishways on irrigation barrages in Japan from site studies, a model experiment of N barrage which is typical as a recent irrigation barrage. The results are below. (1) Low capability for weaker fishes than Ayu. Most of irrigation barrages have pool and weir fishways designed for Ayu which is the most important fish for fishing. (2) Instability of fishway inlet water level - Back water level can\u27t be controlled with old irrigation barrages. Accordingly, flow state in a fishway may be unstable. (3) Obscurity of fishway inlets - Discharge over the barrage is conducted in whole width of the barrage with irrigation barrages. (4) Damages by flooding and scouring