| Literature shows that many scholars at home and abroad focus on the flow field and velocity distribution of Vertical Slot Fishways,which promotes the development of fishway structure.However,few scholars regard Water Profiles as the research focus,and the overall study of the vertical pond water profiles and the change rule of the Water Profiles when the width of the vertical pond changes are not systematic enough.The calculation and rational design of Water Profiles of vertical pond fishway affect the safety and economic cost of vertical seam fishway project.When the fishway surface forms a curve of water saturation,the depth increases,the height of the fishway side wall needs to increase,and the amount of engineering and cost of fishway will increase accordingly.When the precipitation curve is formed on the fishway surface,the water depth becomes shallower and the increase of velocity is easy to form a velocity barrier,which prevents fish from reaching the purpose of fishway project.When the width of vertical slot of fishway changes and the water level of upstream and downstream of fishway changes,the extent and scope of the influence of water profiles is not clear,so it is necessary to study the influence of the change rule of vertical slot water profiles.In this paper,the effect of the width of vertical slot of a single pond on the hydraulic characteristics of fishway is studied by physical model test.In order to provide reference for the future vertical slot fishway engineering design and construction,through physical model and numerical simulation,systematic study of vertical slot fishway water profiles.Results of this study:(1)When the upstream and downstream water depths do not match,the range of influence on the distribution of water profiles along the fishway mainly concentrates on the several stage pond at the tail,and the variation law of water profiles is different in backwater condition and precipitation condition.In the condition of backwater,the water depth in the backwater area increases evenly.However,in the case of precipitation,the water depth of each ponds in the fall area does not conform to the law of uniform decrease.The closer it is to the downstream side,the faster the water depth falls.(2)In the fishway in the process of actual operation,when the downstream water depth is less than the upstream water depth of operation conditions,due to the fishway room number level at the end of the pool depth is reduced obviously,thus water drawdown value increases more,there may be some pool indoor vertical pond section head drop value than fishway grams design flow velocity value to use head drop,will undoubtedly hinder the mother back at this time.Therefore,fishway should be closed when upstream water depth is significantly higher than downstream water depth(3)When the width of single-stage vertical fissure of unilateral vertical fissure is narrowed,backwater curve is formed in the upstream side pool chamber of the vertical fissure,and the water depth in the downstream side pool chamber decreases suddenly first and then recovers quickly.With the increase of vertical fissure narrowness of fishway(k=0.9-K =0.6),the amplitude of water depth in the upstream pond increases,and the affected area of the upstream side also increases,and the number of affected ponds increases correspondingly,while the change of water depth in the downstream side is not obvious,and the number of affected ponds is relatively small.(4)When the vertical joint is narrow,the head drop at the 15# vertical joint increases with the increase of the narrow degree of the vertical joint(k=0.9-K =0.6);When the narrowness of vertical seam band k=0.9,the increase of head drop is not obvious and will not affect fish upstream.When k=0.8 and K =0.7,the increase of head drop is obvious,which may affect fish upward tracing.When k=0.6,the increase of head drop is obvious,which may affect fish upward movement.(5)M software can be used to simulate the water surface line of unilateral vertical slit fishway.The water depth of upstream is equal to the water depth of downstream.M software simulation results are the best.Secondly,the backwater surface curve of the upstream water depth is less than the downstream water depth;The relatively poor result is the fishway precipitation surface curve with upstream water depth greater than downstream water depth.(6)For the single-side vertical fissure fishway of class 50 tank,whether the upstream water depth is higher than the downstream water depth,or the upstream water depth is lower than the downstream water depth,the variation of fishway water depth is mainly concentrated in the latter half(between 1#-40# tank),while the variation of fishway water depth in the upper half(between 40#-50# tank)is relatively small;The gradient of water depth variation is also obviously different in the 1#-40# basin where the variation of fishway water depth is more concentrated.Comparatively,the gradient of water depth variation between 1#-30# basin is larger.This means that the range of water depth variation is mainly concentrated at the end of the fishway in the range of 15～30 grades.Whether in different backwater fall conditions or different precipitation fall conditions,the place where 1/2 fall occurs will move upstream with the increase of fall.There is an obvious linear relationship between the occurrence place of half of the backwater curve and the different fallings of the backwater curve,while there is a nonlinear relationship between the occurrence place of half of the precipitation curve and the different fallings of the precipitation curve.(7)When the vertical seam of unilateral vertical seam fishway is narrow,the range of influence on the upstream side increases with the increase of the number and degree of vertical seam;The influence range on the downstream side is relatively small,only affecting 1～2 pools.The flow barrier is likely to be formed at the most downstream side of the narrow vertical slot when the multistage vertical slot of the unilateral vertical slot occurs.(8)When the water depth of the upstream of unilateral vertical seam fishway changes periodically,the water depth wave is transmitted to the downstream very quickly,and the wave peak attenuation is particularly fast.In only 40 ponds,the wave peak attenuation is 80%,about60 hours,and the overall fishway water depth returns to normal.When the upstream water depth of unilateral vertical slit fishway changes periodically,due to the structural particularity of unilateral vertical slit fishway,except for 100# tank(upstream),the water depth of other tank from receiving the influence of waves to return to normal water depth,the time required is longer than 24 hours. |
