Initial Study Of A Evaluation Index System For Vertical Slot Fishway And Its Problem Pool Diagnosis

The construction of dams and weirss has brought huge economic and social benefits,at the same time,disrupting the connectivity of rivers,causing the fragmentation of fish habitats,hindering the migration of fish and nutrients in the original rivers,and seriously threatening fish habitats and leding to a decline in aquatic biodiversity.So engineers built a variety of fish passage facilities,including fishway,to restore river connectivity and help fish to complete their life history.At present,the vertical slot fishway is widely installed for adapting upstream and downstream water level changes and meeting the needs of different species,but there is no vertical slot fishway effectiveness indicator system,and there is no problem pool diagnostic method of vertical slot fishway.In this paper,the grass carp(Ctenopharyngodon idellus)juveniles of four major fishes were taken as research objects,and the vertical slot fishway was established in the automatic water tank to analyze the effecttiveness of the grass carp juvenile in the vertical slot fishway,establishing an evaluation index system for the effectiveness of fishway.Through the analytic hierarchy process to empower each indicator,and the quantitative evaluation of the effectiveness of vertical slot fishway is realized.Based on evaluation result of vertical slot fishway effectiveness,it finds out the shortcomings of the fishway,and proposing the corresponding problem pool diagnosis method,quickly locating the vertical slot fishway’s problem pool,and analyzing the swimming behavior of the fish in the problem pool;Finally,through the RNN model,a passage effency prediction model for the vertical slot fishway is established at the passage effency of each pool;The upper quartile of the passage time of the fish in each pool was counted,and the passage time of the 12-18 pool was predicted by the ARIMA model.The main findings are as follows:(1)Through fish-fishing experiment in the vertical slit fishway in the laboratory,four indexes for measuring the effectiveness the vertical slot fishway are preliminarily obtained,including entry efficiency,entry time,passage efficiency and passage efficiency.(2)Using the COX proportional hazard regression to analyze the relationship between the entry rate and the passage efficiency and the body length,temperature and conditions of the fishway.Body length has a significant impact on entry efficiency,body length has a significant impact on passage efficiency,and flow rate,velocity,slope and other factors have a significant impact on passage efficiency.According to kruskal-wallis rank sum test,flow rate,velocity,slope and other factors have a significant impact on the entry time and passage time of fish.(3)According to the principles of holistic,scientific,representative and operability,four indicators such as entry rate,entry time,passage rate and passage time are selected,and the weights of each evaluation index are allocated by analytic hierarchy process.Using the multi-attribute utility theory,the final score of the fishway’s effectiveness is calculated.The corresponding fishway effectiveness evaluation grade was worked out to realize the quantitative evaluation of fishway effectiveness of vertical slot fishway.(4)By counting the passage time of fish in each pool,through the outlier processing and K-means clustering method,it is determined that the fish passes through the slow pool and combines with the fish to produce the retreat behavior of the pool,the preliminary diagnosis of vertical slot fishway problems was achieved.The swimming behavior of fish in problem pool was analyzed by analyzing the residence video of fish in problem pool.(5)The circulation neural network was used to construct the prediction model of each pool of the vertical slot fishway,and the prediction model was verified by the relevant fish-fishing experiment,and the model could accurately predict the rate of each level of the pool of the vertical slot fishway.