Experimental Approach to the Hydraulics of Vertical Slot Fishways

An experimental approach to the hydraulics of vertical slot fishways. Page 1 EXPERIMENTAL APPROACH TO THE HYDRAULICS OF VERTICAL SLOT FISHWAYS By J. PUERTAS1, Aff. Member, ASCE, L. PENA2, T. TEIJEIRO3 https://ascelibrary.org/doi/10.1061/%28ASCE%290733-9429%282004%29130%3A1%2810%29Abstract: “This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. This material be found at URL/link of abstract in the ASCE Library of Civil Engineering Database” Fishways are hydraulic structures that enable fish to go through transverse obstructions to continue their upstream migrations. This paper presents the results of a scale model of a vertical slot fishway. The performance of two particular designs of vertical slot fishways for two different slopes was studied in a wide range of discharges. Water depths were measured in almost the whole surface of pools. A linear relation between dimensionless discharge and depth of flow, and the same flow patterns for each design were found. With an acoustic Doppler velocimeter (ADV), three-dimensional velocities were measured at several levels in the entire pool to detect the structure of the flow and quantify velocity distribution. Two different regions in flow patterns were found: a direct flow region characterized by maximum velocities; and a recirculation region, defined by low velocities and horizontal eddies. For a given slope, the velocity at any point of the pool (particularly at the slot) may be considered independent of the discharge and constant with the depth. Some suggestions on kinetic turbulent energy are also made. INTRODUCTION Fish populations in rivers are highly dependent on the characteristics of their aquatic habitat, since it provides the support for all their biological functions. This dependency is more critical in the case of migratory fish which require different habitats to complete their life cycle (Larinier et al. 1998). Anadromous fish species (Salmonidae, Clupeidae, Petromyzontidae...) have to overcome several obstacles in their migration upstream which may prevent their free ascension to the spawning areas. These obstructions, which can be of natural origin (gorges, rapids, waterfalls) or man-made (usually hydraulics works of different types: dams, barriers, watermills...), prevent, as a direct consequence, the natural migrations of fish up and in some cases downstream. This restriction of the “free circulation” of fish is known as the barrier effect, which makes it impossible for the migratory fish to complete their life cycle. It also isolates and separates fish population, drastically diminishing the number of local species. Fish passage structures and vertical slot fishways in particular try to minimize the An experimental approach to the hydraulics of vertical slot fishways. Page 2 1 Prof., Civil Engineering School, A Coruña University, Campus de Elviña, s/n, 15912, A Coruña, Tel: (+34)981 167000 Ext. 5185, Fax: (+34) 981167179, E-mail: [email protected]c.es 2 Res., CITEEC, A Coruña University, Campus de Elviña, s/n, 15912, A Coruña, Tel: (+34)981 167000 Ext. 5185, Fax: (+34) 981167179, Email: [email protected] 3 Prof., EPS, Santiago de Compostela University, Bernardino Pardo Ouro, s/n, 27002, Lugo, Tel: (+ 34) 982 223 325 Ext 23250, Fax: (+ 34) 982 241 835, E-mail: [email protected] negative effects caused by transverse hydraulics constructions and to facilitate the exploitation of species over a wider extension (Larinier et al. 1999). For any fishway to be considered effective, it must allow fish to easy access to the fishway inlet, as well as letting fish go through the fishway with no delay, stress or injury, so that they can head for their spawning areas in a natural way. Although biological and hydraulic aspects are essential to developing a good design of a specific fishway and, therefore, being able to minimize negative impacts on migratory river fauna, it must be remembered that all damages that might be caused by an obstacle can never be fully compensated by fishways. The earliest vertical slot fishways was developed by Milo C. Bell and built at the Hell´s Gate on Fraser River, Canada (Clay, C.H. 1995). A vertical slot fishway consists of a rectangular channel with a sloping bed divided by baffles into a number of pools. Water travels down the channel through vertical slots, passing from one pool to the next one below (Wu et al., 1999) until it finally reaches the river past the obstacle. The difference in water level between the upper and lower end of the fishway is divided into a number of small falls (Rajaratnam et al. 1986). Water flows through the slot like a jet and its energy becomes dissipated by the mixing of the jet in the pool. Fishways must attract fish towards the inlet and let them ascend, so that the water velocity in the flume must not overcome the fish burst speed (Beach, B.H., 1984). Vertical slot fishway must also provide resting zones in the pools for the migratory fish so that they may recover their swimming ability after this great exertion. Vertical slot fishways are widely used in small dams (<5 m.) and natural obstructions where discharges are uncontrollable or undergo great variations. The overwhelming advantage of vertical slot fishways is their adaptability to variations in water levels while their hydraulic performance remains stable. A study of hydraulic characteristics of vertical slot fishways in laboratory model was performed. At the same time, not included here, a numerical simulation of the flow was conducted using the experimental data obtained to calibrate a significant model based on the Finite Volume Method, including turbulence terms. An experimental approach to the hydraulics of vertical slot fishways. Page 3 Previous experimental research on the hydraulics of vertical slot fishways was taken into account. In the research project carried out at the University of Alberta (Canada) by Rajaratnam et al. (1986, 1992, 1999) 18 different designs were studied for the following range of slopes So=5, 10 and 15%. In all of them it was found a linear relationship between dimensionless discharge Q* and a relative flow depth yo/bo existed, where Q* was defined as 5* oobgSQQ , Q being the discharge of the fishway, So the geometrical slope of the fishway and bo the slot width; yo is the average depth of flow measured at the center of the pools. Taking into account hydraulic criteria such as turbulence levels, the circulation patterns in the pool, the jet velocities and energy dissipation and some other factors like simplicity of design or financial cost, they concluded that for 8bo wide and 10bo long pool designs, the fishway performance was satisfactory. On the basis of the designs studied, Rajaratnam et al. (1992) recommended designs 6, 16 and 18 for practical use (Fig. 1). The recommendations of Larinier et al. (1998) for pool dimensions also entail a length of 8-10b and a width of 6-8b, and are very similar to the ones proposed by Rajaratnam et al. (1992). Wu et al. (1999) went further in the study of design 18, and concluded that for a slope of 5%, the main flow travels from one slot to the next through the pool as a 2D curved jet with two recirculation regions, one on each side. For slopes of 10% and 20% the main flow is 3D. The flow at the slot was not perpendicular to the slot. The maximum velocity at the slot was approximately equal to hg2. This paper, in an attempt to continue the line of the research begun by Wu et al. (1999) on the detailed study of the designs recommended as effective by Rajaratnam et al. (1992), focuses on an experimental hydraulic characterization of a scale model of the other two particular vertical slot fishway designs: the so-called design T1 (similar to design 16) and design T2 (similar to design 6). Slight changes were made in their construction in order to adapt them to the existing facilities at the hydraulic research laboratory. The configurations and dimensions of pools are shown in Fig. 2b and Fig. 2c. To study flow patterns for both design, an experimental program was planned and a detailed study of depth and velocity fields was conduced, since these are the two most important parameters on the hydraulic performance of vertical slot fishway. The relationship between the discharge and the depth is the main factor used to determine the hydraulic performance of the fishway. Depth patterns are important in establishing the water distribution in pools to ensure a minimum water level, enough to allow the passage of the species in question, as well as in adopting design criteria for the fishway height. In addition, the velocity value must be compatible with swimming capabilities of the species concerned and it should determine low velocity flow zones and critical zones which fish will require burst speed (Beach, M.H. 1984). An experimental approach to the hydraulics of vertical slot fishways. Page 4 EXPERIMENTAL ARRANGEMENT The experimental work was carried out at the CITEEC (Centro de Innovación Tecnolóxica en Edificación e Enxeñería Civil) at the Universidade da Coruña (Spain). The fishway scale model consisted of a metallic structure 12 m long with a 1x1 m2 rectangular section. The fishway scale model was constructed in such a way as to be able to adopt different slopes. The fishway was divided into eleven pools: a head tank receiving the water from an upstream reservoir, nine active pools and a tailtank. The first four pools presented a T2 configuration, the next were transition type pools and the last four pools had a T1 configuration. The flume bed, side walls and the baffles separating the pools were made of transparent plexiglass sheets (1 cm thick) making it possible to observe the flow. Baffles were always vertical, despite of the slope in the fishway model. The experimental measurements were recorded in pools number 3 and 7 (Fig. 2a). Water was supplied by a hydraulic closed circuit. Discharges was measured by means of an electromagnetic flowmeter. All the elements in the hydraulic circuit were automated and their operation was centralized in a control computer. Three variables were defined for the arrangement of the experimental study: fishway slope, discharge, and boundary condition. The slopes most frequently used at these types of structures vary between 5-10% (Clay, C.H. 1995 and Larinier et al. 1998), hence it was decided to evaluate the fishway for two of them, the first near the lower limit, (So=5,7%) and the second, in the vicinity of the upper limit (So=10,054%). The slope value and physical dimensions of the pools determine the limits of discharge range that the model is able to assume; the maximum discharge employed was 125 l/s, for a slope of So=10,054%. The minimum discharge providing enough water depth for the functioning of the measurement instruments was set close to 15 l/s and 35 l/s for So= 5,7% and So=10,054% respectively. Test discharges differed approximately by 10 l/s between them. A conceptual state of uniform flow (Rajaratnam et al. 1986, 1992) was used, so that the mean depth measured at the middle transverse section was the same in all the pools. At the lower end of the flume a tailgate, causing overflow was used to reach the necessary boundary conditions for the uniform flow in each discharge-slope relationship. A cartesian positioner was placed over the experimental pools in order to automate the positioning of the measurement instruments (Fig. 3). The MAC (Multiuse Axis Control) runs the movement of the electric motors (one on each cartesian axis, X and Y) which draw the supporting metallic beam on which the measurement instruments are fixed. This supporting beam can also be drawn vertically (axis Z). The measurement instruments can, therefore, be set automatically at any point in the pool (3D mesh). Two measurement devices were placed on the cartesian positioner, but not simultaneously: a depth probe and ADV velocimeter. An experimental approach to the hydraulics of vertical slot fishways. Page 5 Velocities were measured by means of a Doppler effect velocimeter (MicroAcoustic Doppler Velocimeter SonTek). The MicroADV is a remote sensing device which has the advantage of being inherently drift-free and does not require routine recalibration. The probe is submerged in the flow and the receivers are slanted at 30º from the axis of the transmit transducer and focus on a common sampling volume, for a total measurement volume of 0.08 cm3 . The volume is located at 5 cm from the probe to reduce flow interference. The maximum MicroADV sampling rate is 50 Hz. Through the MicroADV Data Acquisition System the specific velocity for the three cartesian axis (Vx,Vy,Vz) was obtained for each data point (Kraus et al. 1994; Nikora et al. 1998). Velocity measurements were carried out in planes parallel to the flume bed with 10 cm in between, starting at 5 cm from the channel bed up to as close as possible to the water surface. In each plane, data points were distributed forming a 10x10 cm mesh, reduced to 5x5 cm in critical zones. Therefore a three-dimensional mesh of 10x10x10 cm for the measurement of velocity was maintained. An example of the mesh in one of the planes parallel to the bed for a T1 configurations is shown in Fig. 2d. Water surface height in the pools was measured by means of a conductivity-based depth probe, DHI Wave Gauge Type 202. The DHI Wave Gauge is comprised of two thin parallel stainless steel electrodes. A conditioning signal module (DHI Wave Meter Conditioning Module Type 102E) receives, processes and amplifies the electric sign sent by the wave gauge. Depth measurements in the pools were evaluated following a bidimensional mesh with data points at a 10x10 cm maximum separation in between. Calibration tests were performed prior to each working day. A summary of experimental measurements is shown in Table 1. It must be taken into account that the number of measurement planes for the velocity field are variable, thus in the T1 configuration with a slope of 5,7% and a discharge of 35 l/s, 3 planes parallel to the bed were measured; while in the T1 configuration with a slope of 10,054% and a discharge of 125 l/s, 6 planes parallel to the bed were measured. After a previous experimental tests, a measurement frequency of 15 Hz was chosen. The instrument stayed at each data point for 10 and 15 seconds to collect data on depth and velocity, respectively. Data storage was carried out by a data acquisition program (VirtualBench-Logger, National Instruments). Considering an average of 4 planes parallel to the bed with an average of 132 data points of velocity in each plane (1 data point=675 single data of velocity), 356400 velocity data for each discharge of a given slope and type were measured, all of which provided a large amount of collected data. ANALYSIS OF THE EXPERIMENTAL RESULTS The first relationship to be analyzed is the one between dimensionless discharge and depth. Subsequently, some of the relationships between the different characteristic depths (maximum, minimum, mean, at the slot) are shown, as well as depth An experimental approach to the hydraulics of vertical slot fishways. Page 6 distribution at the surface of the pool and in some longitudinal vertical sections. As a consequence, each individual pattern for every configuration should be known, as well as the effects of th slope and discharge on the depth distribution. When analyzing velocity fields, the distribution of the water velocity has been represented over planes parallel to the bed in order to characterize the different regions into which the velocity field can be divided: recirculation regions and direct flow region. Later, the vertical distributions of velocity values are displayed in order to evaluate their dependence on discharge and velocity. A specific study of the velocity at the slot was done to understand the limitation that this velocity imposes on the design of vertical slot fishways, as these values will be compared with swimming ability of fish. The passage of migratory fish through the fishway is directly related to the turbulence and aeration in pools. The global energy dissipation per volume unit was used traditionally as an indicator of the turbulence levels in the pools. Also presented is the turbulent kinetic energy from the experimental velocity measurements. For the representation of the experimental results, the following dimensionless variables were chosen: So, geometric slope of the fishway, Yo/b, relative flow depth at the transverse middle section, QA, dimensionless discharge. In previous studies the following dimensionless discharges were proposed: Rajaratnam et al. (1986) 5* oobgSQQ   1  Kamula (2001) 32** LbSgQQ oo   2  where Q* and Q** are dimensionless discharges, and L is the pool length. It was considered important not to make the dimensionless discharge dependent on the fishway slope in order to detect the individual performance of the fishway for each slope. On the other hand, if the characteristic length L remains invariable (L=1.2 m) for all the designs in our tests, there is no point in including it in the dimensionless parameters. Hence, a new definition for the dimensionless discharge is proposed: Present Data 5 bgQQA  3  Due to its utility, the dimensionless Q* was used to make the overall comparison of the results obtained in the different designs and for the different slopes including these data and those ofRajaratnam et al. (1992). It must be taken into account that the characteristic length of the slot bo was used by Rajaratnam et al. (1986,1992) in some cases, to define the real width of the slot and in other cases, merely a reference width. In this study b has always been set to the real width of the slot (Fig. 1 and Fig. 2). A summary of the most significant data from the experiments performed is givern in Table 2, where, Yb is the depth at the slot and Ym is the average depth in the pool, being Ymax and Ymin being the maximum and minimum depth in the pool An experimental approach to the hydraulics of vertical slot fishways. Page 7 respectively (all the depth measures represent the vertical distance between the bed and the water free surface). Vb is the velocity at slot,  bbd VbYQC  is a discharge coefficient which is provided to permit a comparison with those given by Rajaratnam et al. (1992) and  0 LWYgQSE o  is the energy dissipation rate in the pool. DEPTH-DISCHARGE EQUATION Following the indications by Rajaratnam et al. (1986), a simple analysis was carried out to determine the flow equations which establish the relationship between the discharge and the depth:         b Y QA0  4  where 5 bgQQ A is the dimensionless discharge in the fishway model, Yo/b is the relative flow depth, and ,  are coefficients relating the dimensionless discharge and the relative flow depth. It has been verified that the values obtained for all the different cases tested matched a linear relationship, that is to say, in every case where =1, and that the  coefficient depended on the configuration of baffles and the slope. The trivial condition is Yo=0 when Q=0 has been imposed on the regression straight line, which implies that the independent term does not exist. The experimental results: relative depth Yo/b versus the nondimensional discharge are given in Fig. 4a, and the corresponding flow equations are shown in Table 3. The  values are proportional to the slope. A higher value for the proportionality factor (steepest line) means that for the same discharge the depth reached is lower and therefore the velocity profiles should increase, which implies a greater efficiency in conveyance. The designs were also compared by grouping the experimental results obtained for both slopes; for this reason So was included in the nondimensional discharge Q* (Equation 1). The values in the fishway model and in the equations are presented the Fig. 4b and the Table 3, respectively. Although the performance of both designs was very similar for each slope, it was also observed that given the same depth value in both designs, it was the T1 configuration that had the lower discharges. A comparison between our results and the ones obtained by Rajaratnam et al. (1992) was carried out including designs 6, 16 and 18 (Fig 1). The discharge was non-dimensionalized by Q* Eq.1 and the results were converted to an standard prototype values (Clay, C.H. 1995) with 0.305 m wide slot (b=0.305 m) using Froudian scaling formulae. The characteristic length bo, was redefined in the results by Rajaratnam (1992), using the real slot length, b. The experimental observations converted to the standard prototype are shown in Fig. 5. The discharge-depth equations were found with the condition of Yo=0 when Q=0 (Table 4) which also includes the values provided by Wu et al. (1999) for the D18 design. The results obtained show An experimental approach to the hydraulics of vertical slot fishways. Page 8 that for designs D16 and T1, which are very similar in construction, the discharges equations are also very similar, while for T2 design (similar to D6 in construction) the value of its proportional constant is notably larger. The simplicity of T2 design versus T1 design provides a greater conveyance capacity which explains the higher values in the proportionality coefficient. The lower value of the discharge coefficient in D6 design versus D16 design does not appear to have a physical explanation. DEPTH DISTRIBUITON The average depth at the middle transverse section has been chosen to verify the performance of the design, but it is also important to know the values of other characteristic depths as Ymax, Yb, Ym and Ymin. Each of these provides us with information on a particular feature of the fishway: wall design criteria (Ymax), the limitations that depth may impose on the passage of fish (Ymin) as well as giving the depth at critical sections (Yb). A linear relationship has been found between each of the different characteristic depths and the relative flow depth at the middle transverse section Yo/b,  ´ 0 ´   bYbY  5  where Y stands for any of the characteristic depths, ´,´ are coefficients which depend on the related characteristic depths, as well as on the slope and on the configuration of the baffles. These relationships can be found in Table 3. The depth at the slot was found to have a value that was quite similar to the average depth in the pool. In Fig. 6, the experimental results for the different characteristic depths versus Yo/b are shown, along with the corresponding equations (straight lines graphs) for T2 design for a slope 5,7%. It is suggested that the experimental relations between the different depths should not be extrapolated for very low depth values, since, for the near zero discharge values, all depth values will converge at a null value. Additional effects such as surface tension forces will come into play when discharges are so small. WATER SURFACE Typical level contours can be observed in Fig. 7, in the four experimental situations studied and with a single discharge of 0.065 m3/s. There is always a region of great depths just upstream of the slot as well as in the region downstream of the pool, nearest to the larger baffles. At the slot point itself there is a sharp drop in the depth and continuing along down the slot, in the direction of the jet, there is a region of minimum depths as a consequence of such decay. Depth patterns are quite independent of flow rates. An experimental approach to the hydraulics of vertical slot fishways. Page 9 Since the configurations patterns of the water surface are independent of discharges, the performance of the vertical slot fishway remains stable with variations in flow rates. This stability is one of the most important characteristic in terms of the application of vertical slot fishway. In spite of similar performance of the two configurations, we must remember that the shallowest region is located in the T1 design near the longitudinal central line. This is due to the different orientation of the main flow when it comes out of the slot, approximately parallel to the sidewalls in the T2 configurations and moving diagonal up to the far corner in the T1 configuration. Another noticeable difference is seen in the different configurations of the level lines joining these water surface points with the same depth, which in design T2 are perpendicular to the longitudinal axis (Fig 7c, profile AA´) while in design T1 they are perpendicular to diagonal line (Fig. 7a, profile BB´). Water depths measured in the section parallel to the longitudinal axis, joining both slots (AA´) and with a discharge of 0.065 m3/s, are shown in Fig. 8. In both designs the largest depth values were reached for the slope of So=10,054%. There is a rapid drop of depth which corresponds to the transition from the slot to the depression region immediately below, and a gradual increase untill the next slot is reached. The greatest relative drop in the depression pertained to a slope of 10,054%. VELOCITY FIELD AND FLOW PATTERNS The configurations of the velocity fields in the pools are one of the main factors used to determine the characteristics of the flow. Velocity fields taken in planes parallel to the bed are shown in Fig. 9, where horizontal components (Vx and Vy) of the velocity vectors can be seen. A reference vector is included in order to make the comprehension of the figures more intuitive. Generally, two different kinds of regions are formed: one, which will be referred to as the direct flow region, where the flow circulates in a curved trajectory at a high speed from one slot to the next downstream; and the others, which will be refered to as recirculation regions, characterized by slower velocities, flow in the opposite direction, owing to the existence of vertical axis eddies. Two recirculation regions of different sizes and separated by the direct flow region, are shown in the flow patterns; the larger one is located close to the long baffles and the smaller one, near the short baffles. In design T1 the streamtrace of the main flow travels towards the center of the pool continuing up until it reaches the slot downstream in a curved trajectory, whereas in design T2 the streamtrace of the main flow travels in a straighter direction, parallel to the flume sidewalls from one slot to the next, creating, as a consequence, a minor mixing of the jet coming from the slot and the water volume in the pool. This difference in the configurations of the main flow trajectory is one of the main reasons why it is necessary to explain the different hydraulic performance of both designs. An experimental approach to the hydraulics of vertical slot fishways. Page 16 APENDIX II. NOTATION The following symbols are used in this paper: b = slot real width; bo = slot characteristic width from Rajaratnam et al. 1992; Cd = coefficient of discharge; E = energy dissipation; g = acceleration due to gravity; h = vertical distance from the bed; k, kA = turbulent kinetic energy and dimensionless turbulent kinetic energy; L = length of pool; Q = discharge; Q* = dimensionless discharge from Rajaratnam et al. (1992,1986); Q** = dimensionless discharge from Kamula, R. (2001); QA = dimensionless discharge from present data; S0 = bed slope; Vm = depth-average velocity; Vb = velocity at slot; Vmb = depth-average velocity at slot; Q mb V = discharge and depth-averge velocity at slot; Vx ,Vy ,Vz = velocity at a point on X,Y,Z axis; Y = depth of flow (measured in vertical) ; Yo = uniform flow depth, mean depth at middle traverse section (measured in vertical); Yb = flow depth at slot (measured in vertical); Ym = mean flow depth at pool (measured in vertical); Ymax = maximum flow depth at pool (measured in vertical); Ymin = minimum flow depth at pool (measured in vertical); W = width of pool; h = difference between upstream and downstream depth at slot;  = density of fluid; An experimental approach to the hydraulics of vertical slot fishways. Page 17 Table 1. Summary of present experiments. Depth Velocity Design T1 T2 T1 T2 So 5,7% 10,054% 5,7% 10,054% 5,7% 10,054% 5,7% 10,054% Range Q 16-85 35-115 25-85 35-125 16-85 35-125 25-185 35-125 Nº Discharge 8 9 7 9 8 9 7 9 Points/Level 89 111 109 109 101 140 132 132 An experimental approach to the hydraulics of vertical slot fishways. Page 18 Table 2. Summary of experimental results. All measurements are model data with b=0.16 m in the T1 design and b=0.15 m in the T2 design. Des. So Q (m3/s) QA Y o (m) Yb (m) Ym (m) Ymax (m) Ymin (m) Vb (m/s) Cd Ed (W/m3) T1 5,7 0.0159 0.4945 0.125 0.158 0.130 0.175 0.107 0.86 0.73 71.81 T1 5,7 0.0209 0.6529 0.176 0.195 0.179 0.215 0.143 0.85 0.79 67.13 T1 5,7 0.0246 0.7669 0.190 0.230 0.197 0.236 0.167 0.79 0.85 72.99 T1 5,7 0.0341 1.0624 0.253 0.306 0.262 0.313 0.212 0.88 0.80 75.94 T1 5,7 0.0458 1.4277 0.379 0.406 0.386 0.425 0.356 0.84 0.83 68.25 T1 5,7 0.0540 1.6827 0.437 0.476 0.445 0.483 0.400 0.87 0.82 69.74 T1 5,7 0.0641 1.9983 0.488 0.529 0.495 0.540 0.453 0.89 0.85 74.18 T1 5,7 0.0741 2.3104 0.604 0.604 0.608 0.652 0.562 0.88 0.87 69.35 T1 5,7 0.0859 2.6791 0.665 0.697 0.674 0.711 0.628 0.85 0.91 72.97 T1 10.05 0.0348 1.0847 0.155 0.201 0.171 0.253 0.093 1.25 0.86 223.25 T1 10.05 0.0445 1.3879 0.247 0.278 0.262 0.357 0.178 1.20 0.83 179.76 T1 10.05 0.0551 1.7174 0.314 0.371 0.331 0.420 0.242 1.21 0.77 174.88 T1 10.05 0.0643 2.0059 0.366 0.406 0.378 0.469 0.288 1.19 0.83 175.00 T1 10.05 0.0751 2.3425 0.436 0.505 0.452 0.541 0.363 1.25 0.75 171.72 T1 10.05 0.0849 2.6482 0.489 0.553 0.507 0.597 0.429 1.00 0.96 172.94 T1 10.05 0.0945 2.9478 0.526 0.561 0.541 0.634 0.443 1.17 0.90 179.16 T1 10.05 0.1044 3.2554 0.581 0.621 0.596 0.690 0.513 1.05 1.01 179.11 T1 10.05 0.1150 3.5856 0.641 0.681 0.656 0.755 0.556 1.06 1.00 178.79 T2 5,7 0.0160 0.5855 0.102 0.109 0.152 0.061 0.682 0.95 1.05 88.18 T2 5,7 0.0250 0.9153 0.169 0.180 0.225 0.122 1.125 0.93 0.97 83.64 T2 5,7 0.0350 1.2811 0.263 0.274 0.323 0.214 1.750 0.99 0.84 75.23 T2 5,7 0.0453 1.6585 0.350 0.362 0.408 0.298 2.336 1.00 0.81 72.96 T2 5,7 0.0540 1.9772 0.439 0.449 0.497 0.376 2.928 0.97 0.82 69.39 T2 5,7 0.0639 2.3405 0.524 0.531 0.577 0.475 3.495 1.09 0.72 68.82 T2 5,7 0.0741 2.7131 0.606 0.613 0.660 0.552 4.040 0.87 0.92 69.02 T2 5,7 0.0840 3.0785 0.670 0.679 0.732 0.615 4.468 0.96 0.82 70.81 T2 10.05 0.0253 0.9277 0.134 0.138 0.208 0.080 0.892 1.14 0.75 188.43 T2 10.05 0.0352 1.2912 0.206 0.202 0.276 0.132 1.375 1.23 0.79 170.20 T2 10.05 0.0453 1.6601 0.248 0.251 0.329 0.152 1.656 1.32 0.79 181.73 T2 10.05 0.0549 2.0100 0.307 0.311 0.405 0.212 2.048 1.32 0.80 177.95 T2 10.05 0.0645 2.3644 0.371 0.372 0.461 0.275 2.471 1.27 0.85 173.48 T2 10.05 0.0746 2.7325 0.431 0.432 0.515 0.330 2.873 1.31 0.83 172.42 T2 10.05 0.0838 3.0718 0.483 0.480 0.569 0.380 3.222 1.33 0.83 172.81 T2 10.05 0.0954 3.4955 0.536 0.539 0.623 0.437 3.577 1.30 0.85 177.17 T2 10.05 0.1048 3.8398 0.578 0.578 0.657 0.483 3.853 1.30 0.87 180.66 T2 10.05 0.1151 4.2177 0.615 0.612 0.714 0.505 4.100 1.46 0.80 186.50 T2 10.05 0.1248 4.5739 0.650 0.649 0.745 0.536 4.332 1.28 0.91 191.39 An experimental approach to the hydraulics of vertical slot fishways. Page 19 Table 3. Flow equations, relationship between dimensionless discharge and relative depths. In parentheses, correlation coefficent (r2). Design So QA Y min/b Yb/b Ymax/b Ym/b Q* T1 5,7% 0.631Yo/b (0.9946) 0.9739Yo/b-0.1409 (0.9986) 0.9758Yo/b+0.2512 (0.9944) 0.9993Yo/b+0.3018 (0.9992) 1.015Yo/b (0.9998) 2.7289Yo/b (0.9872) 10.054% 0.8888Yo/b (0.9889) 0.9742Yo/b - 0.3822 (0.9979) 1.0008Yo/b+0.2918 (0.9933) 1.021Yo/b+0.6133 (0.9996) 1.033Yo/b (0.9987) T2 5,7% 0.6867Yo/b (0.9903) 0.9789Yo/b-0.2871 (0.9994) 1.031Yo/b+0.0407 (0.9983) 1.0065Yo/b+0.3583 (0.9997) 1.0183Yo/b (0.9994) 3.0382Yo/b (0.9783) 10,054% 0.9988Yo/b (0.9903) 0.9196Yo/b-0.4069 (0.9965) 0.9949Yo/b+0.2826 (0.9949) 1.0323Yo/b+0.4811 (0.9982) 1.0002Yo/b (0.9997) An experimental approach to the hydraulics of vertical slot fishways. Page 20 Table 4. Relationship between dimensionless discharge and relative depth with 5* oobgSQQ . In parentheses, correlation coefficent (r2). Present Data Rajaratnam et al. (1992) Wu et al. (1999) bYQ oT 7289.2 * 1 (0.9872) bYQ oD 6878.2 * 16  (0.9981) bYQ oD 7745.3 * 18  (0.9761) bYQ oD 75.3 * 18  bYQ oT 30382.3 * 2 (0.9783) bYQ oD 2787.2 * 6 (0.9406) An experimental approach to the hydraulics of vertical slot fishways. Page 21 Table 5. Discharge-averaged mean velocity at slot. Q mb V (cm/s) Desi g n So=5,7% So=10.054% T1 85.63 115.21 T2 96.99 126.47 An experimental approach to the hydraulics of vertical slot fishways. Page 22 Table 6. Energy dissipation rate for fishway model and for standard prototype with a slot width b=0.305 m. E (W/m3) Model Desi g n So=5,7% So=10.054% T1 71.44 177.49 T2 70.57 181.06 Prototype (b=0.305 m) Desi g n So=5,7% So=10.054% T1 98.63 245.05 T2 100.63 258.18 An experimental approach to the hydraulics of vertical slot fishways. Page 23 Table 7. Specific values of turbulent kinetic energy. k (cm2/s2) Q=65 l/s Q=75 l/s Q=85 l/s T y pe, So h Zlow Z inter Z high Zlow Z inter Z high Zlow Z inter Z high hbed 148 529 1958 342 677 1797 122 722 1818 T1, 5% h 25 cm 168 810 863 194 889 1554 238 915 1281 hsurface 331 927 1734 328 653 2211 249 565 3329 hbed 123 224 598 133 208 689 149 243 774 T2, 5% h 25 cm 142 498 355 103 222 378 160 219 464 hsurface 216 371 1810 137 361 2955 184 580 1989 hbed 351 675 8890 298 797 3440 234 1000 3501 T1, 10% h 15 cm 232 1586 5450 363 1321 2035 382 1099 2822 hsurface 171 1554 3404 181 1310 2983 285 998 3938 hbed 92 472 1080 167 384 1268 131 521 1643 T2, 10% h 15 cm 293 767 727 190 592 815 260 447 810 h surface 255 581 651 277 880 1389 287 1130 919 An experimental approach to the hydraulics of vertical slot fishways. Page 24 Fig. 1. Details of designs 6, 16 and 18, recommended for practical use by Rajaratnam et al. (1986, 1992). An experimental approach to the hydraulics of vertical slot fishways. Page 25  b   b        b T2=150 bT1=160 Unit: milimeters Fig. 2. a) Dimension of the laboratory model of a vertical slot fishway. b and c) Details of T1 and T2 designs. d) Data point mesh in a parallel plane to the bed for T1 design and a slope of 10,054%. An experimental approach to the hydraulics of vertical slot fishways. Page 32 0Cm 50 100 150 0Cm 5 0 100 Axis Y Axis X R e f e r e n c e v e c t o r :1m / s e g Flow a) 0cm 50 100 100 5 0 0cm Axis X Axis Y R e f e r e n c e V e c t o r 1m / s c) Flow Fig. 9. Horizontal velocity fields, Vx-Vy in planes parallel to the bed for several experimental situations: a) Design T1, S=5,7%, Q=85 l/s, h=35 cm; b) Design T1, S=10,054%, Q=105 l/s, h=5 cm; c) Design T2, S=5,7%, Q=54 l/s, h=25 cm; d) Design T2, S=10,054%, Q=75 l/s, h=25 cm 0Cm 50 100 150 0Cm 5 0 100 Axis Y Axis X Reference Vector: 1 m/seg Flow b) 0cm 50 100 100 5 0 0cm Axis X Axis Y R e f e r e n c e V e c t o r 1m / s d) Flow An experimental approach to the hydraulics of vertical slot fishways. Page 33 a) b) c) Fig. 10. Flow patterns in pools: a) Design T1, So=5,7%; and So=10.054% with QA<2.75. b) Design T1, So=10.054% with QA>2.75. c) Design T2. An experimental approach to the hydraulics of vertical slot fishways. Page 34 a) b) Reference Vector: 1 m/s X Z 020 40 60 80 100 120 0 10 20 30 40 50 60 70 Unit: cm. Fig. 11. Velocity fields, Vx-Vz in vertical planes parallel to longitudinal axis of fishway. a) T1 design, So=5,7%, Q=0,065 m3, Y=72 cm b) T2 design, So=10,054%, Q=0,0746 m3, Y=86 cm R e f e r e n c e V e c t o r : 1 m / s X Z 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 An experimental approach to the hydraulics of vertical slot fishways. Page 35 a) b) 0 10 20 30 40 50 60 0 50 100 150 200 Vx (cm/s) h (cm) Q=65 l/s Q=85 l/s Q=95 l/s Q=105 l/s Q=125 l/s Pt. 2 Pt. 3Pt. 1 Fig. 12. Vertical distributions of velocity values at some points for several discharge. a) T2 design, S0=10,054% in: Pt. 1 x=76 cm, y=46 cm; Pt. 2 x=76 cm, y=11 cm; and Pt. 3 x=56 cm, y=86 cm. b) T1 design, So=5.7% in: Pt. 4 x=36 cm, y=12 cm; and Pt. 5 x=36 cm, y=62 cm. 0 10 20 30 40 50 60 70 0 50 100 150 200 Vx (m/s) h (cm) Q=85 l/s Q=75 l/s Q=65 l/s Q= 55 l/s Q=45 l/s Q=35 l/s Pt.4 Pt. 5 An experimental approach to the hydraulics of vertical slot fishways. Page 36 a) 0 20 40 60 80 100 120 30 40 50 60 70 80 90 100 110 120 Q (l/s) Vm(cm/s) x=46 cm, y=64cm x=6 cm, y=79 cm x=6 cm, y=84 cm x=56 cm, y=9 cm x=116 cm y=46.5 cm x=26 cm,y=84 cm b) 0 20 40 60 80 100 120 140 10 20 30 40 50 60 70 80 90 Q (l/s) Vm (cm/s) x=16 cm, y=86 cm x=6 cm,y=91 cm x=66 cm,y=11 cm x=36 cm,y=36 cm x=86 cm, y=56 cm Fig. 13. Velocity evolution against discharge at several experiemental data points. a) T1 design, So=10.054; b) T2 design, So=5.-7%. An experimental approach to the hydraulics of vertical slot fishways. Page 37 a) 0 20 40 60 80 100 120 0 10203040506070 h (cm) Vb (cm/s) Q=15,85 l/s Q=20,94 l/s Q=24,6 l/s Q=34,1 l/s Q=45,8 l/s Q=54 l/s Q=64,1 l/s Q=74,1 l/s Q=85,9l/s b) 0 20 40 60 80 100 120 140 160 0 102030405060 h (cm) Vb (cm/s) Q=35.2 l/s Q=45.3 l/s Q=54.8 l/s Q=64.5 l/s Q=74.6 l/s Q=83.8 l/s Q=95.4 l/s Q=104.8 l/s Q=124.8 l/s Fig. 14. Values of the slot velocity against distance to the bed for several discharges. a) T1 design, So=5.7%; b) T2 design, So=10.054%. An experimental approach to the hydraulics of vertical slot fishways. Page 38 0 20 40 60 80 100 120 140 160 0 20406080100120140 Q (l/s) Vmb (cm/s) Design T1, So=5,7% Design T1, So=10,054% Design T2, So=5,7% Design T2, So=10,054% Fig. 15. Depth average slot velocities versus discharge. An experimental approach to the hydraulics of vertical slot fishways. Page 39 0 50 100 150 200 250 0.00 0.03 0.05 0.08 0.10 0.13 0.15 Q (m3/s) E (W/m3) Design T1, So=10,054% Design T2,So=10,054% Design T1, So=5,7% Design T2, So=5,7% Fig. 16. Energy dissipation values versus circulating discharge in the model. An experimental approach to the hydraulics of vertical slot fishways. Page 40 0cm 50 100 100 50 0cm Eje X Eje Y Reference Vector 100 cm/s k 1500 1333 1167 1000 833 667 500 333 167 0 Zlow Zinter Zhi g h 0Cm 50 100 150 0Cm 50 100 Eje Y Eje X Reference Vector 100 cm/s k 1500 1333 1167 1000 833 667 500 333 167 0 Zlow ZinterZhigh a) b) Fig. 17. Contour lines of turbulent kinetic energy (cm2/s2) for a discharge of Q=0.085 m3/s. a) Design T1, So=10.054%, h=30 cm; b) Design T2, So=5.7%, h=60 cm . An experimental approach to the hydraulics of vertical slot fishways. Page 41 Fig. 18. Dimensionless turbulent kinetic energy, averaged on the vertical for design T1 and So=10.054%. Kinetic Turbulent Energy, Design T1, So=10,054% 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 25 35 45 55 65 75 85 95 105 115 Q (l/s) KA Zlow Zinter Zhigh