The study of weir and fishway in 3,528 rivers in Korea, including national and provincial rivers, shows there are 34,012 weirs and 5,018 Fishways.
According to this research, the nationwide installation rate of Fish-way is 14.9% , and about 34.4% of this would meet the criteria of upstream migration...
The study of weir and fishway in 3,528 rivers in Korea, including national and provincial rivers, shows there are 34,012 weirs and 5,018 Fishways.
According to this research, the nationwide installation rate of Fish-way is 14.9% , and about 34.4% of this would meet the criteria of upstream migration of fish and 60.8% needs to improve the conditions and 4.8% has lost the capacity as a Fish-way and has to install the facility again.
In reality, the installation of the Fish-way facility in Korea has less than 5% and this leads to the primary cause of decrease in the fish migration ratio of the upstream and downstream of the rivers.
The survey of the fish migration ratio from the radius of the 5 big rivers in Korea shows that it has less than 20% of fish migration ratio in half of the rivers regardless of the tributary stream of and it has indicated that most of the streams has low fish migration ratio in Korea.
The inadequate condition of constructed Fish-way and low rate of fish migration ratio has caused the severance between the upstream and downstream of rivers and led to the genetic heterogeneity within the species in the river which will destroy the ecological health of the environment. Moreover, the decline of the financially viable migratory fish, such as sweet fish(Plecoglossus altivelis), Japanese eel (Anguilla japonica), will lead to loss of earnings to the local fishery business and insecure income to the local residence with decline of fresh-water fishery. These are the great concern for the preservation of the natural fish environment.
Most of the Fishway system constructed in Korea has imported systems from America, Canada, Australia and Japan, instead of designing for our own unique environment and these imported systems in use were simply bench marked and not compatible with our traditional fishery system to preserve our natural fish ecology.
These systems were not able to adapt national river conditions and negligence of its maintenance questions the basic capability as a fishway.
It should have considered it is for the passage of fish not for human when constructed the system of the fishway and should have focused on how fast and easily the fish will travel upstream.
However, the most of the constructed fish-way systems would not meet the standards and it was simply showcased the concrete shape of a fishway by the ignorant behavior of people. It has been misguided by highlighting as a water friendly and agree well in the aspect of landscape in the name of natural fishway.
These should have been designed and constructed to provide the path for fish movement instead of subjectively highlighting of fit in the landscape and water friendliness.
Therefore, it calls urgent attention of the government to clarify the formal definition of fishway type to impose the strict regulation and provide technical assistant for the installation of the fishway system and financial support to improve the environment of the rivers.
Hereafter, the fish way should have improved in functionally advanced technology with the help of government procurement system such as NARAJANGTER. then it would function as a primary fishway for natural habitat for fish and fish passage to improve movement of fish and coexist with humans in harmony.
First of all, it requires the development of eco-convergence type of fishway which support preservation of the natural habitats. The eco-convergence type of fishway should support the vegetation and ecology in nature and should have the essence of the fish way in combination with structured and natural fishway system. The natural fishway system consider the water friendliness and aspect of landscape. The structured fishway should have combine the efficiency, functionality and durability of the fishway system.
Moreover, the ineffective fishways should have replaced or remodeled with the eco-convergence type of fishway to improve the movement of fish, name it as ‘ecological passage for fish’. With the eco-convergence type of fishway, the fish migration ratio would be increased and the ecological health of the rivers would be recovered to maintain the stream ecosystems.
In consequently with the previous research, this study focused on fishways in rivers and its evaluation of the systems in the radius of the big 5 rivers and the fish migration ratio of each streams and also focused on how to improve and develop the best facility for fishway system and set the standard and rules and regulations to maximize the function of fishway facilities in Korea.
For this reasons, this study suggested the river design standards should include the necessary specifications of water velocity, water depth, the distance between the walls and the slope for the fishway, so the upstream migration of fish would not be lost to the bird for feed and it should be able to prevent the fry being eaten by the adult fish with the help of stabilized hydraulic structure, then it could provide the ecological space for spawning and shelter for fish.
This study also suggested that the river design standards should protect the scenic nature of the river with minimum destruction of environment by the concrete structure and proper use of vegetation to maintain the consistent flow of water.
This study suggested that new eco-convergence fishway type can produce molds and actual size of prototype to demonstrate numerical analysis of flows for hydraulic and physical stability, which are the important nutritional factors to the upstream migration of fish, by modelling the water velocity and Eddy current distribution of streams and testing compressive strength by nondestructive examination, to assess the function and structural stability as a high strength structure in the river and to ensure the quality of the fishway.
Through this research, the newly developed eco-convergence fishway type contributes the conservation of nature and the ecological quality for vegetation and fish’s shelter by convergence structured fishway based on Ice-harbor type fishway which is the most efficient and outstanding fishway among 4 standard type of fishway recommended by river design standards.
The eco-convergence fishway type block will function in a situation of lowering the water level of rivers by engineering the overflow wall in arc structure which is high in center and lower in edges and constructed in curved surface structure to prevent the damage of blocks by loose rocks or pebbles in flowing down when it is flooded.
With through research, the planting species, Pussy willow((Salix gracilistyla), Phragmites japonica Steud, and Curvedutricle Sedge (Carex dispalata) were selected according to river plant data sheet and study of experiments by take rooting as well as growth experiments and these perennial water plants do not obstruct the water flow in streams and grow well in water channel.
It has confirmed that prototype fishway blocks can perform well when it was installed in the middle of flow stream tested by nondestructive examination and it shows more than 30Mpa of compressive strength.
By use of “COMSOL” program, considering the average national height of weir, fishway structure 2mW×1mH, The velocity of the outlet fishway 0.1 m/s, slope 1/20, in these conditions, the assessment of numerical analysis of flows and hydraulic characteristics of the eco-convergence fishway block indicates the overflow velocity within the fishway is in the range of 0.5∼1.0 m/s which is satisfactory results by river design standards and non-overflow velocity in pool is very low and no sign of a circling current prove to be a good fish shelter for fry and small fish and a resting place for upstream migratory fish.
It has evaluated and predicted the possibility of the problems when the eco-convergence fishway type applied in actual place and it has proved that there is no possibility of loss of vegetation, no possibility of withering of the plants, no possibility of Sediment influx in the space of fish’s shelter.
With these findings, the” restoration of Oriental White Stork(Ciconia boyciana) as a village business” to highlight the ecological health of migration of fishes and condition of inhabitation on the riverbasin would expand to other regions starting from Muhancheon(in Yesan City) tributary and small stream in Simokcheon to set the standard design.
This study contributed the development of the eco-convergence fishway type and it has greatly improved the previously structured in monotony concrete fishway and low efficient of Overall stone pitching-type fishway and rapids-type fishway
And it provides fish the most important aspect of ecological functions of fish way and this new concept is the first in the world with the most advanced technology. Hereafter, this new development will bring the diversity of fishway type and restore the ecological health of rivers as well as converting the existing fish-way to ‘ ecological fishway for fish’.
The study of weir and fishway in 3,528 rivers in Korea, including national and provincial rivers, shows there are 34,012 weirs and 5,018 Fishways.
According to this research, the nationwide installation rate of Fish-way is 14.9% , and about 34.4% of this would meet the criteria of upstream migration of fish and 60.8% needs to improve the conditions and 4.8% has lost the capacity as a Fish-way and has to install the facility again.
In reality, the installation of the Fish-way facility in Korea has less than 5% and this leads to the primary cause of decrease in the fish migration ratio of the upstream and downstream of the rivers.
The survey of the fish migration ratio from the radius of the 5 big rivers in Korea shows that it has less than 20% of fish migration ratio in half of the rivers regardless of the tributary stream of and it has indicated that most of the streams has low fish migration ratio in Korea.
The inadequate condition of constructed Fish-way and low rate of fish migration ratio has caused the severance between the upstream and downstream of rivers and led to the genetic heterogeneity within the species in the river which will destroy the ecological health of the environment. Moreover, the decline of the financially viable migratory fish, such as sweet fish(Plecoglossus altivelis), Japanese eel (Anguilla japonica), will lead to loss of earnings to the local fishery business and insecure income to the local residence with decline of fresh-water fishery. These are the great concern for the preservation of the natural fish environment.
Most of the Fishway system constructed in Korea has imported systems from America, Canada, Australia and Japan, instead of designing for our own unique environment and these imported systems in use were simply bench marked and not compatible with our traditional fishery system to preserve our natural fish ecology.
These systems were not able to adapt national river conditions and negligence of its maintenance questions the basic capability as a fishway.
It should have considered it is for the passage of fish not for human when constructed the system of the fishway and should have focused on how fast and easily the fish will travel upstream.
However, the most of the constructed fish-way systems would not meet the standards and it was simply showcased the concrete shape of a fishway by the ignorant behavior of people. It has been misguided by highlighting as a water friendly and agree well in the aspect of landscape in the name of natural fishway.
These should have been designed and constructed to provide the path for fish movement instead of subjectively highlighting of fit in the landscape and water friendliness.
Therefore, it calls urgent attention of the government to clarify the formal definition of fishway type to impose the strict regulation and provide technical assistant for the installation of the fishway system and financial support to improve the environment of the rivers.
Hereafter, the fish way should have improved in functionally advanced technology with the help of government procurement system such as NARAJANGTER. then it would function as a primary fishway for natural habitat for fish and fish passage to improve movement of fish and coexist with humans in harmony.
First of all, it requires the development of eco-convergence type of fishway which support preservation of the natural habitats. The eco-convergence type of fishway should support the vegetation and ecology in nature and should have the essence of the fish way in combination with structured and natural fishway system. The natural fishway system consider the water friendliness and aspect of landscape. The structured fishway should have combine the efficiency, functionality and durability of the fishway system.
Moreover, the ineffective fishways should have replaced or remodeled with the eco-convergence type of fishway to improve the movement of fish, name it as ‘ecological passage for fish’. With the eco-convergence type of fishway, the fish migration ratio would be increased and the ecological health of the rivers would be recovered to maintain the stream ecosystems.
In consequently with the previous research, this study focused on fishways in rivers and its evaluation of the systems in the radius of the big 5 rivers and the fish migration ratio of each streams and also focused on how to improve and develop the best facility for fishway system and set the standard and rules and regulations to maximize the function of fishway facilities in Korea.
For this reasons, this study suggested the river design standards should include the necessary specifications of water velocity, water depth, the distance between the walls and the slope for the fishway, so the upstream migration of fish would not be lost to the bird for feed and it should be able to prevent the fry being eaten by the adult fish with the help of stabilized hydraulic structure, then it could provide the ecological space for spawning and shelter for fish.
This study also suggested that the river design standards should protect the scenic nature of the river with minimum destruction of environment by the concrete structure and proper use of vegetation to maintain the consistent flow of water.
This study suggested that new eco-convergence fishway type can produce molds and actual size of prototype to demonstrate numerical analysis of flows for hydraulic and physical stability, which are the important nutritional factors to the upstream migration of fish, by modelling the water velocity and Eddy current distribution of streams and testing compressive strength by nondestructive examination, to assess the function and structural stability as a high strength structure in the river and to ensure the quality of the fishway.
Through this research, the newly developed eco-convergence fishway type contributes the conservation of nature and the ecological quality for vegetation and fish’s shelter by convergence structured fishway based on Ice-harbor type fishway which is the most efficient and outstanding fishway among 4 standard type of fishway recommended by river design standards.
The eco-convergence fishway type block will function in a situation of lowering the water level of rivers by engineering the overflow wall in arc structure which is high in center and lower in edges and constructed in curved surface structure to prevent the damage of blocks by loose rocks or pebbles in flowing down when it is flooded.
With through research, the planting species, Pussy willow((Salix gracilistyla), Phragmites japonica Steud, and Curvedutricle Sedge (Carex dispalata) were selected according to river plant data sheet and study of experiments by take rooting as well as growth experiments and these perennial water plants do not obstruct the water flow in streams and grow well in water channel.
It has confirmed that prototype fishway blocks can perform well when it was installed in the middle of flow stream tested by nondestructive examination and it shows more than 30Mpa of compressive strength.
By use of “COMSOL” program, considering the average national height of weir, fishway structure 2mW×1mH, The velocity of the outlet fishway 0.1 m/s, slope 1/20, in these conditions, the assessment of numerical analysis of flows and hydraulic characteristics of the eco-convergence fishway block indicates the overflow velocity within the fishway is in the range of 0.5∼1.0 m/s which is satisfactory results by river design standards and non-overflow velocity in pool is very low and no sign of a circling current prove to be a good fish shelter for fry and small fish and a resting place for upstream migratory fish.
It has evaluated and predicted the possibility of the problems when the eco-convergence fishway type applied in actual place and it has proved that there is no possibility of loss of vegetation, no possibility of withering of the plants, no possibility of Sediment influx in the space of fish’s shelter.
With these findings, the” restoration of Oriental White Stork(Ciconia boyciana) as a village business” to highlight the ecological health of migration of fishes and condition of inhabitation on the riverbasin would expand to other regions starting from Muhancheon(in Yesan City) tributary and small stream in Simokcheon to set the standard design.
This study contributed the development of the eco-convergence fishway type and it has greatly improved the previously structured in monotony concrete fishway and low efficient of Overall stone pitching-type fishway and rapids-type fishway
And it provides fish the most important aspect of ecological functions of fish way and this new concept is the first in the world with the most advanced technology. Hereafter, this new development will bring the diversity of fishway type and restore the ecological health of rivers as well as converting the existing fish-way to ‘ ecological fishway for fish’.
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