| The fishway is one of the important engineering measures to protect or reshape the river’s ecological environment,and it is also an important means to restore the vertical connectivity of the river.Fish swimming ability is a basic factor that must be considered when designing a fishway,and is a key factor in the design of a fish-passing facility.China started late in fishway construction,and the fish swimming capacity data is relatively scarce,especially the lack of swimming data for Cobitidae and Schizothorax.It is necessary to carry out swimming capability tests for Cobitidae and Schizothorax.At present,the testing and evaluation of swimming capacity indicators are mainly carried out in a Loligo Systems swim test tank.Loligo Systems swim test tank have gradually been accepted by researchers due to their advantages such as mature technology,convenient transportation,and simple operation.However,due to the relatively small test area of Loligo Systems swim test tank,fish Swimming is passive and the form is relatively simple.It lacks the consideration of autonomous behavioral response to current conditions.It is necessary to further develop the swimming ability and behavior of fish in an open-channel flume to better provide a reference for fishway design.In this study,we take the Diptychus maculatus Steindachner,Triplophysa tenuis in the Tarim River Basin,Xinjiang,Schizothorax wangchiachii,and Paracobitis variegatus was used as the research object to study the swimming ability and behavior of fish using two different swimming ability test methods(Loligo Systems swim test tank and open-channel flume).Through the above studies,we provided parameters and theoretical support for the design of water velocity in key parts of the imitation natural fishway in Muzhati River,Xinjiang,and Songxin fishway in Sichuan.The main research contents and conclusions of this paper are as follows::(1)The basic swimming indicators of the target fish were systematically tested under the Loligo Systems swim test tank.The result shows: the induced velocity of the Diptychus maculatus Steindachner in a Loligo Systems swim test tank are 0.18 ± 0.02m/s,the critical swimming speed is 1.02 ± 0.15m/s,the burst swimming speed is 1.39 ± 0.17m/s,and the sustained swimming speed is no greater than 0.87m/s,the prolonged swimming speed of 0.87 ～ 1.37m/s;the induction velocity of Triplophysa tenuis is 0.18 ± 0.02m/s,critical swimming speed is 0.95 ± 0.23m/s,burst swimming speed is 1.16 ± 0.21m/s,the sustained swimming speed is not greater than 0.85m/s,the prolonged swimming speed is 0.85m/s ～ 1.25m/s;the induction velocity of Schizothorax wangchiachii is 0.09 ± 0.03m/s,and the critical swimming speed is 1.32 ± 0.25m/s,burst swimming speed is 1.81 ± 0.22m/s,the sustained swimming speed is not greater than 1.3m/s,the prolonged swimming speed is 1.30 ～ 1.80m/s;the induction velocity of Paracobitis variegatus is 0.06 ± 0.02m/s The critical swimming speed is 0.98 ± 0.12m/s,the burst swimming speed is 1.16 ± 0.15m/s,the sustained swimming speed is not greater than 0.70m/s and the prolonged swimming speed is 0.70 ～ 1.30m/s.(2)In an open-channel flume,,the ability to test of the Schizothorax wangchiachii and Paracobitis variegatus was tested.The results showed that: when the water velocity is 0.67 ～ 1.52m/s,it will not cause water velocity barriers to the 6-meter upwards of the Schizothorax wangchiachii;when the water velocity is 1.16 ～ 1.52cm/s,it will cause water velocity barriers to the 6-meter upwards of Paracobitis variegatus.The retrospective success rate and the retrospective distance of the Schizothorax wangchiachii showed a linear relationship,and the retrospective success rate decreased significantly as the retrospective distance increased(P <0.05).The retrospective success rate of Paracobitis variegatus also decreased with increasing body length(P <0.05).When the water velocity was 0.67m/s and 1.07m/s,the two conditions showed a linear decreasing trend.When the velocity is 1.16m/s and 1.52m/s,the success rate of retrospective and the distance of retrospective exponentially decrease.The average maximum distance of the Schizothorax wangchiachii and Paracobitis variegatus was calculated under four conditions.The maximum distance of the Schizothorax wangchiachii was linearly decreasing with the increase of the water velocity.The relationship is:2y(28)-54.389x(10)594.08(R(28)0.6253).The retrospective distance decreases exponentially with the increase of the water velocity,and the fitted relationship between the two is as follows:1.295 21342.2(R 0.7567)xy e-(28)(28).(3)The maximum swimming speed is 347.77cm/s of Schizothorax wangchiachii and the maximum swimming speed is 271.85cm/s of Paracobitis variegatus in an open-channel flume.Comparing test results in Loligo Systems swim test tank and open-channel flume,it was found that the swimming speed tested in open-channel flume was greater than that tested in Loligo Systems swim test tank,except for 0.67m/s.Testing the fish’s swimming ability in open-channel flume can help improve the accuracy of the test results.(4)Through the analysis of the open channel specific flow field conditions,the analysis of the traceability and behavior of the Schizothorax wangchiachii and Paracobitis variegatus.the result shows: under the three conditions,except for the condition II,there is no significant difference in the success rate of the Schizothorax wangchiachii and the Paracobitis variegatus through the four vertical slot(P > 0.05).Under condition I,the Schizothorax wangchiachii and the Paracobitis variegatus had a success rate of 65.22% and 100%,respectively;under the condition III,the Schizothorax wangchiachii and the Paracobitis variegatus had a success rate of 77.14% and 51.43%,respectively.According to this study,it is known that when the design water velocity of the vertical slot of Songxin fishway is 0.75m/s,it will not cause the velocity barriers to the upward moving of the Schizothorax wangchiachii and the Paracobitis variegatus.The time for the experimental fish to pass through the vertical slit was found that there was no significant difference in the time spent to pass through the four vertical slot under the three conditions for the Schizothorax wangchiachii and the Paracobitis variegatus(P <0.05).(5)Under the condition of specific flow field,the method of superimposing the flow field with the traceback trajectory of the fish and using the statistical method of probability density function is used to analyze the preferred water flow velocity of the Schizothorax wangchiachii and the Paracobitis variegatus.The analysis shows that the preference range for the upstream flow field of the Schizothorax wangchiachii is 0.84m/s～0.96m/s,and the preference range for the upstream flow field of the Paracobitis variegatus is 0.75m/s ～ 0.96m/s.Through video analysis,it is found that the swimming pattern of the Paracobitis variegatus is different from that of the Schizothorax wangchiachii.(6)According to this study,the water flow velocity design of the nature-like fishway in Muzati River in Xinjiang and the Songxin fishway in Heishui River in Sichuan are provided,and the recommended reference value is provided for the design of the water flow velocity of the key parts of the fishway.Based on the relationship between the maximum distance and the water flow velocity of the Schizothorax wangchiachii and the Paracobitis variegatus,it can be verified whether the high-velocity zone in the fish pass will cause water velocity barriers to the fish’s go upstream.According to the special habit of tracing back of the Paracobitis variegatus,the bottom of the fishway can be thickened during the design of the fishway and some gravels can be added to facilitate so that the Paracobitis variegatus can swim upstream. |
PDF Full Text Request