• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.2
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• pp.61-71
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• 2014

A river fishway is a hydraulic structure enabling fish to overcome stream obstructions such as dams and weirs. The main aim of this paper is to investigate the collectibility of upstream-migrating fishes and hydraulic problems in pool-and-weir type fishway which has been established for upstream-migration at Namgang weir in the downstream of Namgang dam, and to grope for improvement measures which pool-and-weir type fishway can be switched to pool-and-partial weir type fishway through hydraulic field experiment. Exsisting fishway had problems which upstream-migrating fishes can not take a rest due to the seiche and vortex phenomena in pools and migrate to upstream because of height difference in entrance pool. In order to prevent hydraulically the seiche and vortex phenomena and establish rest area for fishes in each pool, we carried out hydraulic field experiments. In the fishway, it was to improve pool-and-weir into pool-and-partil weir, to decrease the height difference in entrance pool, and to reduce oriffice velocity of each pool. Also, we investigated fishes collectibility of after improving fishway for 6 days in September 2013. To resolve chronic problems(seiche-vortex phenomena and rest area for fishes), as weirs were remodeled into partial weir only which central part of weirs was part of non-overflow weir, we confirmed results that pool-and-weir type fishway could be switched to efficient pool-and-partial weir type fishway with relatively simple construction and low cost. Type-B which has the closed oriffices and the parts of non-overflow has the ideal conditions, but this conditions are limited to fishway of Namgang weir used in this study. Representative Ice-habor type fishway is pool-and-partial weir type fishway which has together parts of overflow and oriffices, and has excellent ability of upstream-migration. To switch from pool-and-weir type fishway to pool-and-partial weir type fishway, the size of oriffice has to be regulated by the discharge of fishway and the dimension on parts of non-overflow and overflow in weirs. Entrance pool is important facility which upstream-migrating fishes have to not only be collect but also charge with energy. In this study, entrance-pool is temporary and roughly-built, but fishes gather together more than the case of no entrance-pool. In the case of fishway which was protruded to downstream, as entrance of fishway turns toward or parallels to weir, the collectibility of fishway was excellent by attraction water.

• Journal of Korea Water Resources Association
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• v.37 no.7
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• pp.541-552
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• 2004

In this paper, ascending functions of the pool-and-weir fishway which has been established for the upstream migration of migratory fish at Jamsil Weir in the lower part of the Han River was assessed by applying tile Existing Fishway Measurement Method, and measures to improve these functions were suggested. The primary fish which ascended the fishway during the period of measurement was Erythroculter erythropterus Basilewsky, greater than 29cm in the body length. A total of 361 individual fish were collected with traps established at the exit of the fishway The maximum ascending capacity for the fish was 2.53${\times}$10^{-3}$ fish/hr/g. The fishway of Jamsil Weir does not satisfy the various fish species inhabiting in the river. Especially, small fishes of lower swimming ability may not ascend the fishway because the difference in water levels between upper and lower pools in the fishway was too large at the exit and there was too much discharge flowing into the fishway. This fishway does not have a roll in the ascending function for other species except Erythroculter erythropterus Basilewsky and Hemibarbus labeo Pallas, for which swimming ability is great. In order to improve the ascending function of the fishway, the structures of the fishway need to be changed so that various species in the river can easily ascend and the fishway function be taken into consideration in operation of the gates of the weir. Additional construction of fishways on both sides of the lower flow channel are needed to correct a decline in the fishway effectiveness due to continuous flow over the fixed part of the weir.

• Journal of Korea Water Resources Association
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• v.56 no.spc1
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• pp.1037-1048
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• 2023

Fishways are constructed to ensure the fish migration because river-crossing structures such as dams and weirs cut off the stream longitudinal connectivity and influence on aquatic ecosystems. However, the passage efficiency of fishes varies depending on flow characteristics in the fishway and fish species. In this study, three-dimensional numerical simulations are carried out using a RANS model and the volume of fluid method for resolving free surface fluctuations to calculate the turbulent flow in the pool and weir type fishway. The Flow velocity and turbulent kinetic energy in the pool of fishway are analyzed according to variation of the upstream water level and the length of pool. The present numerical simulations reasonably well reproduce the stream flow and plunging flow characteristics in the pool. The simulation results show that the stream flow changes to the plunging flow as the length of the pool increases. When the upstream level increases, the stream flow becomes more evident. Key parameters related to the fish migration within the fishway such as the flow velocity and the turbulent kinetic energy are examined to assess the ascending possibility of fishes.

• Water for future
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• v.29 no.6
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• pp.225-235
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• 1996

This study deals with hydraulic characteristics and their effects on upstream migration of fish by the weir type in a pool-weir fishway, and presents an optimal type of weir for an easy upstream migration. Experiment was performed to estimate hydraulic conditions by the weir type and to determine which type was good. The results showed that a rectangular weir with a small rectangular notch installed by a zig-zag type was preferable to a simple weir with no notch or to a trapezoidal weir, since it makes possible for upstream migration even when a water level draws down and moreover, it makes falling flow through a notch which facilitates upstream migration. It was proposed that the notch must be designed that the flow situation may keep the streaming flow so long as the maximum flow velocity does not exceed the critical swiming velocity, i.e., the dimensionless flow rate may exist whthin the range of 0.27 and 0.41.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.99-109
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• 2022

This study was intended to suggest the applicability of stepped boulder fishway using the concept of traditional boulder weir, focusing on the problems of existing concrete pool-and-weir fishways installed in mountain streams. To achieve this purpose, a stepped boulder fishway was designed and constructed as a pilot project in consideration of ascending capacity of the selected target fishes. Under the given discharge conditions, the hydraulic characteristics of the fishway were investigated in the field, and the characteristics and ascending capacity of the fishes were compared and analyzed. The fishway had a short length and steep slope, but the mean drops between each baffle were the range of 0.15 to 0.29 m, and this range satisfied the limit condition of about 0.40 m, which was in the limit of the drop that target fishes can ascend. The mean velocities of each baffle and pool were 0.82 to 0.87 m/sec and 0.13 to 0.24 m/sec. This result satisfied the conditions of burst speed (10 to 30 times of body length) and mean velocity of the resting pool (7 to 25% of burst speed) for target fishes. Since the bottom surface of the pool formed of boulders had a gentle reverse slope and rotational flow did not occur, the efficiency of fishway can be increased, and it will also be possible to solve the maintenance problem by flushing bed materials.

• Water for future
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• v.27 no.2
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• pp.63-72
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• 1994

In this study, hydraulic characteristics for upstream migration of fish in a pool-and-weir fishway were analyzed through experiment. The results showed that streaming flow was preferable to plunging flow for upstream migration of fish and it was not good to make an orifice beneath the septum since it generates turbulent jet and eddies. Protrusions on the side wall of fishway were preferable to grooves since they decelerate flow velocity and make upstream migration easy. A vertically movable septum was necessary for a flushing of deposited bed material, and net installing over fishway was also needed for birds not to approach the fishway and eat fish.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.565-566
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• 2005

• Journal of Korea Water Resources Association
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• v.54 no.1
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• pp.15-25
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• 2021

The purpose of this study was to present the necessity and effect of culvert fishway, based on the absence of design criteria for it which fishes can pass. As an attempt for this purpose, circular culvert fishway were designed hydraulically to meet the passage condition for selected target fish species, and post-monitoring was performed to confirm its effectiveness. In the case of general circular culvert without weir baffles, the target fish species cannot pass because of the constant depth and velocity in the entire reach of the circular culvert, so it was confirmed that resting pools must be installed to help fish passage. In the case of circular culvert with weir baffles, the depth and the mean velocity in resting pool increased by about 240% and decreased by about 70% respectively, which not only satisfied the passage conditions of Zacco platypus that can swim at more than 10 times the speed of body length for 1 to 5 seconds, but also confirmed that various river fish could pass. Post-monitoring results of the restoration reach and fish capture monitoring surveys of circular culvert fishway demonstrated that the target fish species, Zacco platypus, can pass through it.

• Journal of Korea Water Resources Association
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• v.45 no.3
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• pp.317-329
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• 2012

It is increasing to make an efforts on preventing natural river environment and preserving natural river ecosystem as development is unavoidable. In the case of inconsistent river flow caused by reservoir development, fishway is an alternative to secure fish diversity and preserve existing river ecosystem but existing fishway was established without full study for their functions. In this study, hydraulic characteristics of natural fishway established on Beakje weir's right side were analyzed. The results show that the fishway has reasonable depth and velocity condition which inhabit condition is enough for a dominant species. For assessing the optimal design of fishway, the Weighted Usable Area (WUA) was calculated by using two dimensional numerical model under the ordinary flow condition. The comparison results for various pool widths in the fishway show that the designed width has maximum WUA for adult Zacco platypus but WUA is maximized with 1m wider pool width than designed width for spawning.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.33-42
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• 2022

In this study, flow patterns in the ice-harbor fishway were analyzed according to fluctuations of the upstream water level, an increase of weir interval, and the presence or absence of orifices using a three-dimensional commercial numerical model, Flow-3D. In order to prove the suitability of the numerical simulation results, the flow velocity and flow rate at the exit of the fishway were observed using a 3D ultrasonic velocimetry on an actual ice-harbor fishway installed downstream of the Daegok bridge in Gyeongan-Cheon. Four types of turbulence modules can be selected for the Flow-3D model. As a result of verification with observation data, the RNG model best described the flow characteristics in the ice-harbor fishway. The velocity structure in the fishway according to fluctuations of the upstream water level was simulated. The results showed that the plunging flow and the streaming flow were mixed at the lowest water level. When the water level increased about 10 cm or more from the lowest water level, the plunging flow disappeared in all pools and only the streaming flow occurred. Contrary to expectations, even when the water level is rose a little, the flow simply occurred mainly on the streaming flow. If the interval between the weirs is increased, both the plunging flow and the streaming flow are showed continued even if the water level rises. In addition, compared to the case where there are no orifices at the bottom of the weirs, the plunging flow tends to be generated in several pools. It is necessary to prevent blocking orifices through active management so that various flow patterns in the fishway can be generated in multiple pools.