Design and effectiveness evaluation of a fish guide weir

Abstract

Fish passage facility design must account for the migration routes and gathering locations of fish within the river. Given the variability and unpredictability of fish migration routes and gathering locations, effectively guiding fish migration is a major focus in fish conservation. This paper presents an innovative concept and design methodology for a fish guide weir. The effectiveness of the weir is assessed using the Active Fish Migration (AFM) model alongside real fish tests, in conjugation with the fish passage facilities at Yaojiaping Hydropower Station. The key findings are: (1) Fish passage barriers are consistently formed at the fish guide weir, creating a unique low-velocity area downstream that leads to the outlet of the fish-attracting channel, establishing a unique fish-gathering location. (2) The AFM model predicts the fish guiding effect of the weir at Yaojiaping Hydropower Station, noting similar swimming routes under varied operating conditions. Fish migrate upstream along the low-velocity area on the right bank, congregating at the fish-attracting channel's outlet. (3) Real fish tests verify that the Yaojiaping fish guide weir effectively directs fish migration, creating a unique fish-gathering zone at the channel's outlet, thereby affirming the weir's effectiveness. (4) The fish guide weir bisects the river, creating an overflow from the weir crest that forms a waterdrop or velocity barrier, preventing further upstream movement. In addition, the weir's angle relative to the river course facilitates guiding fish migration, establishing a unique fish-gathering area at its upstream end.