Discharge rating equation and hydraulic characteristics of standard Denil fishways

Journal of Hydraulic Engineering



This paper introduces a new equation to predict discharge capacity in the commonly used Denil fishway using water surface elevation in the upstream reservoir and fishway width and slope as the independent variables. A dimensionless discharge coefficient based only on the physical slope of the fishway is introduced. The discharge equation is based on flow physics, dimensional analysis, and experiments with three full-scale fishways of different sizes. Hydraulic characteristics of flow inside these fishways are discussed. Water velocities decreased by more than 50% and remained relatively unchanged in the fully developed flow downstream of the vena contracta region, near the upstream baffle where fish exit the fishway. Engineers and biologists need to be aware of this fact and ensure that fish can negotiate the vena contracta velocities rather than velocities within the developed flow region only. Discharge capacity was directly proportional to the fishway width and slope. The new equation is a design tool for engineers and field biologists, especially when designing a fishway based on flow availability in conjunction with the swimming capabilities of target fish species.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Discharge rating equation and hydraulic characteristics of standard Denil fishways
Series title Journal of Hydraulic Engineering
DOI 10.1061/(ASCE)0733-9429(2003)129:5(341)
Volume 129
Issue 5
Year Published 2003
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Hydraulic Engineering
First page 341
Last page 348
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