Flow characteristics of stream type fishway with cylinder blocks

摘要

In Japanese rivers located in residential areas, there are a lot of planted carp. In some cases, the larger carp eat small fish and shrimp causing the number of small fish and shrimp to decrease rapidly. Especially, diadromous small fish and shrimp distributed throughout the river face a serious problem. It is necessary to protect growth places for small fish and shrimp from predation by the larger planted carp. In this paper, a stream-type fishway with cylindrical blocks has been proposed in order to secure growth places for small fish and shrimp at the upstream side of drop structures. Characteristics of the proposed fishway have been shown and also the flow condition in the fishway has been classified. Velocity fields in the proposed fishway have been shown and may support that swimming fish, other than larger carp to more safely migrate upstream by using the flow along cylindrical blocks.