ABSTRACT
ABSTRACT: In Nagasaki prefecture, Japan, a normal concrete Sabo dam was improved as a slittype Sabo dam slitted at the central part of the dam. In order to arrange a fishway in the slit-type Sabo dam, the authors proposed new fishways for the migration of aquatic animals, such as diadromous shrimps, crabs, and fishes, that migrate between sea and river. This paper discusses the effect of the proposed new fishways on the migration of multi-diadromous aquatic animals that live in the local river, and it introduces a design method for arranging the proposed fishway in a slit type concrete Sabo dam. The measurements of the velocity and the air-concentration downstream of the proposed fishway reveal that a plunging flow with an aerated inflow in a stepped channel is effective as a flow leading toward the entrance of the fishway. Further, experimental results revealed that diadromous crabs, shrimps (i.e., crustaceans), and swimming and benthic fishes can migrate easily upstream and downstream by the proposed fishway.
