Hydraulic performance of fish bypass-pools for irrigation diversion channels

This paper presents the results of an exploratory study on the hydraulics o f a fish bypass-pool that is built to facilitate successful fish passage th rough an irrigation diversion channel. The hydraulic performance of the byp ass-pool was investigated by performing two major experimental runs to eval uate the flow recirculation patterns within the pool when two different out let configurations were used. This was to determine which outlet design pre vents or minimizes the presence of "stagnant" regions within the pool, wher e fish could rest until ensnared by a predator. These experiments show that the flow from the forebay area of the irrigation diversion structure, ente ring the pool as a jet, diffuses because of the circulation and turbulence within the bypass pool. The diffusing jet impinges upon the back-wall of th e pool and dives into the pool creating several recirculation patterns with in the pool. The results collected in this study provide useful information about the jet velocity decay through the pool, the eddy length scale withi n the pool, the velocity contours, and the level of energy dissipation with in the pool. A rational basis was developed for evaluation of the hydraulic performance of a bypass-pool by considering the recirculation pattern and turbulent flow microstructures formed within the pool.