Alternating Side-Baffle Fish Ladder Design for Weak-Swimming Species
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Solution Overview
Problem
Existing fish ladders, such as Denil and Alaskan Steeppass, are ineffective for weak-swimming and small fish species, as they require strong swimming abilities and high water flows, making them expensive, complex, and difficult to maintain, while also being unsuitable for the diverse riverine fish communities in North America.
Innovation Solution
An alternating side-baffle fish ladder design that reduces energy in water flow through V-shaped energy dissipation pockets and maintains slow velocities, allowing small fish to pass through by using specific dimensional relationships between side-baffles and channel width, creating habitats that assist weak-swimming fish in bypassing river obstructions, and is modular, easy to install, and maintain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional full baffle fishways (Denil and Alaskan Steeppass) are used, then strong swimming fish like salmon and trout can pass upstream, but weak-swimming and small fish species cannot pass, and the structure requires high water flows (4-6 cubic feet per second)
Solution Approach 1:
The channel is divided into multiple pools separated by alternating side baffles, creating a stepped progression that allows fish to rest and regain strength between sections. This segmentation reduces the continuous swimming effort required compared to traditional full baffle designs.
Solution Approach 2:
Different regions of the channel have different flow characteristics - the side baffles create localized low-velocity zones and eddies where fish can rest, while maintaining overall upstream flow. This local variation in flow quality allows weak-swimming fish to pass through sections that would be too demanding in a uniform channel.
2Reliability
If traditional full baffle fishways are used, then fish passage function is achieved, but the structure becomes expensive, complex, and difficult to install and maintain
Solution Approach 1:
The fishway is divided into modular pool sections that can be independently constructed and assembled. Each section contains alternating side baffles that are simpler than full cross-channel barriers, reducing overall structural complexity while maintaining fish passage functionality.
Solution Approach 2:
Instead of using full cross-channel baffles that block the entire width, the invention uses side baffles that extend only partially across the channel from one wall. This inverted approach - using partial rather than complete barriers - simplifies the structure while achieving the same flow control and fish guidance functions.
3Reliability
If traditional full baffle fishways are used, then fish passage is achieved, but the structure is damaged by winter icing and floods and requires high water flows to operate
Solution Approach 1:
The channel is segmented into multiple pools with alternating side baffles, creating a more distributed and flexible structure. This segmentation allows the system to better accommodate varying flow conditions - during high flows or flooding, the modular design can handle increased water volumes without the same vulnerability to damage as rigid full-baffle structures.
Solution Approach 2:
The fishway is designed to operate effectively across a wider range of flow parameters - from low flows during drought conditions to high flows during floods. The alternating side baffle configuration maintains functional fish passage at lower water flows (below 4-6 cubic feet per second) while remaining structurally sound during high flow events and winter icing conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively passes small fish of varying sizes and swimming abilities at low and high water flows, reducing energy consumption and debris accumulation, while being cost-effective and easy to maintain, thus addressing the limitations of existing fish ladders.
Implementation Method 1
V-shaped energy dissipation pockets
Implementation Method 2
energy dissipation pockets
Implementation Method 3
zero-negative flow eddies (i.e., a fish resting habitat)
Data Source
AI summary
A fish ladder includes a channel with first and second sidewalls spaced apart at a channel width distance. Each of a first plurality of side-baffles is attached to the first sidewall and each of a second plurality of side-baffles is attached to the second sidewall. Each side-baffle extends a predetermined distance into the channel. A first slot opening width distance from a tip of each one of the first plurality of side-baffles across the channel and perpendicular to the second sidewall substantially equals a second slot opening width distance from a tip of each one of the second plurality of side-baffles across the channel and perpendicular to the first sidewall. A side-baffle spacing distance from a tip of each one of the first plurality of side-baffles and perpendicular to a corresponding one of the second plurality of side-baffles located upstream substantially equals the first and second slot opening width distances.