RU2274702C1 - Method for kinetic flow energy dissipation in fish passing and hatchery channel and fish passing and hatchery channel - Google Patents

Abstract

FIELD: hydraulic structure, particularly fish passing structures adapted to permit broad fish passage through support structures to fish hatchery and growth areas.

SUBSTANCE: fish passing channel comprises waterway having head connected to upper hydrosystem pool and mouth part communicated with lower hydrosystem pool, roughness members and natural flora arranged in layers in floodplain and bed parts of transversal channel section. Waterway is made as channel with polygonal transversal section. Waterway channel has different cross-sections alternating along channel length. Bed channel part is located along central longitudinal part thereof, floodplain channel parts extend along channel banks and made as curvilinear segments in plan view. When working water flow passes main flow part flows through waterway bed part and cooperates with remainder flow part, which flows along floodplain waterway parts formed in convex channel bank areas. Secondary vortex flows with vertical axis of rotation are created in floodplain waterway parts and have flow directions opposite to that of main flow part.

EFFECT: increased efficiency of kinetic flow dissipation and reduced length thereof.

13 cl, 34 dwg

Description

The invention relates to hydraulic engineering, in particular to fish passage facilities designed to allow fish producers to pass through retaining structures to spawning and feeding grounds.

A known method of quenching the kinetic energy of a stream in a fish-spawning canal [1], which consists in passing a working flow of water through a water supply path, the cross section of which is trapezoidal in shape, at the bottom of which there are reinforced roughness elements located at an acute angle to the longitudinal axis of the channel.

The disadvantage of this method is the low efficiency of quenching the kinetic energy of the stream in the water path.

The closest in technical essence and the achieved result is a method of quenching the kinetic energy of a stream in a fish-spawning channel [2], which consists in passing the working water flow through the water supply path, the cross section of which is formed in a polygonal shape with the formation of channel and floodplain parts, at the bottom of which are installed elements of enhanced roughness and natural vegetation.

The disadvantage of this structure is the insufficiently effective quenching of the kinetic energy of the flow, as a result of which the channel length is more extended.

Known fish passage-spawning channel [1], including a gateway regulator located in the head part connected to the upper pool, a water supply path connecting the head part to the mouth part and the lower pool, and reinforced roughness elements installed at the bottom of the channel, throughout its length.

The disadvantage of this structure is the low efficiency of quenching the kinetic energy of the flow in the water path.

The closest in technical essence and the achieved result is a fish passage-spawning channel [2], including a water supply path, the head of which is connected to the upper pool of the hydraulic system, and the mouth part is connected to the lower pool, made in the form of a channel with a cross-section of a polygonal shape, reinforced elements roughnesses and natural vegetation, tieredly located on the floodplain and channel parts of the channel cross section.

The disadvantage of this structure is the insufficiently effective quenching of the kinetic energy of the flow, as a result of which the channel length is more extended.

The aim of the invention is to create effective hydraulic conditions in the fish passageway to quench the kinetic energy of the stream to reduce the total length of the channel.

The invention consists in the following.

According to claim 1 of the claims. Due to the formation of the arrangement of the fish passage tract in the form of channel sections with different polygonal cross sections, it is possible to force the bulk of the stream flowing along the channel part to interact with the rest of the flow flowing on the floodplain parts of the water supply path formed on the convex banks of the channel channel part. At the same time, secondary whirlpool currents with a vertical axis of rotation are formed on the floodplain parts, the flow direction in which is opposite to the direction of the flow of the bulk of the flow flowing through the channel part of the water supply path. Thus, the main stream does additional work, spending part of its kinetic energy on the rotation of the water masses of the floodplain parts of the water supply path.

According to claim 2 of the claims. The implementation of the channel of the water supply path along its length with various options for the cross section (trapezoidal cross section; or the type of "floodplain-channel-floodplain"; or the type of "floodplain-riverbed"; or the type of "river-floodplain"), which alternate one after another, allows, using the effect of sudden expansion or contraction, to achieve additional quenching of the kinetic energy of the water stream. With this arrangement of the channel of the water supply path, the main stream meanders and interacts with the flow of the floodplain part (s). In this case, the channel part of the channel is located along its central longitudinal axis, and the floodplain parts are located along its coastal edges relative to the central longitudinal axis of the water supply path, and the floodplain parts, in plan, are made in the form of curved segments. The segment shape of the floodplain parts fully corresponds to the hydraulic structure of the flow formed inside them - whirlpool areas with a vertical axis of rotation, which are formed during the interaction of the main channel flow and the water flow of the floodplain (floodplain) part.

According to claim 3 of the claims. The implementation of the floodplain parts located along the length of the water supply path of the channel symmetrically with respect to its longitudinal axis is a particular embodiment of its layout. In this embodiment, the channel flow is actively involved, which, tangentially at the interface between the two types of flows, interacts with the masses of water located in the floodplain areas.

According to claim 4 of the claims. The implementation of the floodplain parts located along the length of the water supply path of the channel asymmetrically relative to its longitudinal axis is also a private version of its layout. In this variant, the effect of meandering the channel stream is actively used, which at the same time still spends part of its kinetic energy on the rotation of the masses of water located in the whirlpool areas formed in the floodplain areas.

According to claim 5, claims. The implementation of the bottom of the floodplain parts, located at the same elevation, is a private version of the layout of the cross section of the channel and allows you to create equally probable conditions for spawning of fish on the floodplain parts. In particular, the same water depth on the floodplain parts provides a flow with the same water temperature.

According to claim 6, claims. The implementation of the bottom of the floodplain parts, located at the same elevation, is also a private version of the layout of the cross section of the channel and allows you to create different conditions for spawning of fish on the floodplain parts. In particular, the different water depths in the floodplain provide a flow there with different water temperatures, which expands the possibilities of migrants when they spawn inside the canal.

In addition, different bottom marks of the floodplain parts dictate the presence of different volumes of liquid in these areas, and this moment forces the main channel stream to intensify the meandering effect. This is a consequence of the uneven cost of the main stream for the rotation of the masses of water flows with different volumes. The overall effect of quenching the kinetic energy of the water stream increases.

According to claim 7 of the claims. The implementation of natural vegetation located on the floodplain parts allows to increase the efficiency of spawning of phytophilic fish that spawn on the surface of aquatic vegetation, while the efficiency of the spawning process, under conditions of warmer horizons of the floodplain parts, only increases.

According to claim 8 of the claims. The implementation of the elements of enhanced roughness located at the bottom of the channel part of the channel, in the form of discretely placed elements with the formation of a gap between them, is a private version of their layout design. Migrants have the ability to freely move between the discrete installed elements of enhanced roughness. In addition, discrete elements increase the quenching effect of the kinetic energy of the flow in the bottom horizons.

According to claim 9, the claims. The implementation of the elements of enhanced roughness, placed in a checkerboard pattern, can increase the overall effect of quenching the kinetic energy of the flow in the bottom horizons.

According to claim 10 of the claims. The implementation of the elements of enhanced roughness from a natural material, such as boulders, allows you to create a fish-spawning channel, as close as possible to the flow conditions in natural river streams. In addition, the use of natural building material reduces the cost of building the canal and its operation.

According to claim 11, the claims. The implementation of the elements of enhanced roughness located at the bottom of the channel channel, in the form of rifts, over the entire width of the channel channel bottom allows increasing the efficiency of quenching the kinetic energy of the stream in the bottom horizons. In addition, the presence of transversely arranged elements of enhanced roughness allows the formation of rifts that occur in the conditions of river flow, which also brings the construction of the fish-spawning channel closer to the conditions of flow in natural river streams, which are the natural habitat of fish.

According to paragraph 12 of the claims. The implementation of the elements of enhanced roughness located at the bottom of the channel part of the channel in the form of rifts and not installed on the entire width of the bottom of the channel part of the channel allows the formation of bottom swimming inlets. This arrangement is most favorable for the movement of bottom fish species, such as sturgeons.

According to item 13 of the claims. The location of the riffles with their adjoining either to the left or to the right side allows the formation of bottom swim-in holes with alternating them along the length of the water supply path relative to its central longitudinal axis, while even bottom swim-in holes are adjacent to the right side of the channel, and odd ones are adjacent to left. This arrangement provides equiprobable conditions for the movement of bottom fish along the length of the water supply path.

The solution of this problem is achieved by creating a new method of quenching the kinetic energy in the fish-spawning channel and a new design of the fish-spawning channel.

Graphic material explaining the new design solution is presented in the following drawings:

figure 1 is a fragment of the fish-spawning canal, plan;

figure 2 - section aa in figure 1;

figure 3 is a section bB in figure 1;

figure 4 - section bb in figure 1;

5 is a variant of the cross section of the water supply path of the channel of the type "floodplain-channel-floodplain" with different elevations of the bottom of the floodplain parts;

6 is the same, symmetrical version of figure 5;

Fig.7 is a variant of the cross section of the water supply path of the channel type "channel-floodplain" with placement on the floodplain of natural vegetation;

Fig. 8 is an embodiment of a cross-section of a water supply path of a floodplain-channel-floodplain channel with placement on a floodplain part of natural vegetation;

Fig.9 is the same, a variant with different elevations of the bottom of the floodplain parts;

figure 10 is the same, symmetrical version of figure 9;

11 is a variant of the cross section of the water supply path of the channel of the type "floodplain-channel-floodplain" with an asymmetric placement on the floodplain of natural vegetation;

Fig.12 is the same, symmetrical version of Fig.11;

Fig - variant of the cross-section of the water supply path of the channel of the type "floodplain-channel-floodplain" with asymmetric placement on the floodplain of natural vegetation, with different elevations of the bottom of the floodplain parts;

Fig.14 is the same, symmetrical version of Fig.13;

Fig - variant of the cross-section of the water supply path of the channel of the type "floodplain-channel-floodplain" with asymmetric placement on the floodplain of natural vegetation and with different elevations of the bottom of the floodplain parts;

Fig.16 is the same, symmetrical version of Fig.15;

Fig is a fragment of a fish-spawning canal, plan, version with a symmetrical placement of floodplain parts relative to the channel part of the channel of the channel;

Fig. 18 is a section G-G in Fig. 17;

Fig. 19 is an embodiment of a cross-section of a water supply path of a floodplain-channel-floodplain channel with symmetrical placement on the floodplain part of natural vegetation and with a different elevation of the bottom of the floodplain parts;

Fig. 20 is an embodiment of a cross-section of a water supply path of a floodplain-channel-floodplain channel with asymmetric placement on the floodplain of natural vegetation and with different elevations of the bottom of the floodplain;

Fig - variant of the cross-section of the water supply path of the channel of the type "floodplain-channel-floodplain" with the placement on the floodplain of the spawning substrate in the form of gravel and pebble dumps and with different elevations of the bottom of the floodplain parts;

Fig.22 is the same, an option with the same bottom marking of the floodplain parts;

Fig is a variant of the cross-section of the water supply path of the channel of the type "floodplain-channel-floodplain", symmetrical to the variant in Fig.21;

24 is a variant of a cross-section of a water supply path of a channel of the “floodplain-channel-floodplain” type with discrete elements of enhanced roughness installed at the bottom of the channel part of the channel;

Fig - variant of the cross-section of the water supply path of the channel type "floodplain-channel-floodplain" with discrete elements of enhanced roughness, installed on the bottom of the channel and floodplain parts of the channel;

Fig is a variant of the water supply path with the placement of the floodplain parts in the form of curved segments on the convex banks of the channel part of the channel and elements of enhanced roughness in the form of rifts over the entire width of the bottom of the channel part of the channel;

Fig - the same, the option of placing the rolls is not the entire width of the bottom of the channel of the channel with the formation of bottom swimming inlets;

Fig.28 is a longitudinal section of a water supply path (channel part), an embodiment with the placement of rifts at its bottom;

Fig.29 is a fragment of the water supply path, an option with the placement of rifts on its bottom, isometry;

Fig - the same, the option of placing rifts with the formation of bottom swimming inlets, isometry;

Fig - the same, on the floodplain are placed discrete elements of enhanced roughness;

Fig - the same, discrete elements of enhanced roughness made in the form of boulders;

Fig. 33 is a fragment of the water supply path, a variant with the placement of discrete elements of enhanced roughness, made in the form of boulders and placed at the bottom of the channel and floodplain parts, isometry;

Fig.34 is a fish-breeding and spawning canal as part of the hydraulic system, plan.

Fishery-spawning channel includes a water supply path 1, the head part 2 of which is connected to the upper 3 head of the hydraulic unit 4, and the wellhead part 5 - to the lower 6 of the head, made in the form of a channel with a polygonal cross-section, elements of enhanced roughness 7 and natural vegetation 8, tiered located on the floodplain 9 and channel 10 parts of the channel cross section.

The channel of the water supply path 1 is made in length with various versions of the cross section that alternate one after another, while the channel 10 of the channel is located along its central longitudinal axis, and the floodplain 9 parts are located along its coastal edges relative to the central longitudinal axis of the water supply path 1, floodplain 9 parts, in plan, are made in the form of curved segments 11.

In addition, the floodplain 9 parts can be located along the length of the water supply path 1 of the channel symmetrically relative to its longitudinal axis.

In addition, the floodplain 9 parts can be located asymmetrically along the length of the water supply path 1 of the channel relative to its longitudinal axis.

In addition, the bottom of the floodplain 9 parts can be located at the same elevation.

In addition, the bottom of the floodplain 9 parts can be located at different altitudes.

In addition, natural vegetation 8 can be placed on floodplain 9 parts.

In addition, the elements of enhanced roughness 7 located at the bottom of the channel 10 of the channel can be made in the form of discrete placed elements with the formation of a gap between them.

In addition, the elements of enhanced roughness 7 can be placed in a checkerboard pattern.

In addition, the elements of enhanced roughness 7 can be made of natural material, such as boulders 12.

In addition, the elements of enhanced roughness 7 located at the bottom of the channel 10 of the channel can be made in the form of rolls 13 over the entire width of the bottom of the channel 10 of the channel.

In addition, the elements of enhanced roughness 7 located at the bottom of the channel 10 of the channel can be made in the form of rolls 13 not over the entire width of the bottom of the channel 10 of the channel with the formation of bottom swimming holes 14.

In addition, the bottom swim-in holes 14 can be formed with alternating them along the length of the water supply path 1, relative to its central longitudinal axis, while even bottom swim-in holes 14 are adjacent to the right side of the channel, and odd holes to the left.

On the floodplain parts 9, whirlpool currents 15 are formed.

To overlap the head part 2 of the water supply path 1, it is equipped with a head regulator 16.

At the bottom of the channel 10 parts and floodplain 9 parts, spawning substrate 17 is placed, made in the form of gravel-pebble gravel bed up to 0.5 meter thick.

The method of quenching the kinetic energy of a stream in a fish-spawning channel is as follows.

The bulk of the flow rate passes through the channel 10 of the water supply path 1, which interacts with the rest of the flow flowing on the floodplain 9 parts of the water supply path 1, formed on the convex banks of the channel 10 of the channel, while secondary whirlpools 15 with a vertical axis are formed on the floodplain 9 parts rotation, the flow direction in which is opposite to the flow direction of the bulk of the flow flowing through the channel 10 of the water supply path 1.

Due to the formation of the arrangement of the fish passage tract in the form of channel sections with different polygonal cross sections, it is possible to force the bulk of the stream flowing along the channel 10 part to interact with the rest of the flow flowing on the floodplain 9 parts of the water supply path 1 formed on the convex banks of the channel 10 channel part. At the same time, secondary whirlpool currents 15 with a vertical axis of rotation are formed on the floodplain 9 parts, the flow direction in which is opposite to the flow direction of the main mass of the flow flowing through the channel 10 of the water supply path 1. Thus, the main flow does additional work, spending part of its kinetic energy the rotation of the water masses of the floodplain 9 parts of the water supply path 1.

Fishery-spawning channel works as follows.

The attraction of fish from the lower 6 downstream to the wellhead 5 of the fish-spawning channel is carried out by supplying the working flow from the upper 3 downstream along the water supply path 1 (Fig. 34). The fish, responding to the created hydraulic conditions, actively moves to the inlet head of the channel and, entering its mouth part 5, enters the channel where it spawns in the presence of favorable conditions, or, overcoming the water supply path 1 and the head part 2, goes to the top 3 downstream for further advancement to spawning or feeding grounds. The channel of the water supply path 1 (Fig. 1) is made in length with different cross sections of a polygonal shape (Figs. 2, 3, 4), which alternate one after another, while the channel 10 of the channel is located along its central longitudinal axis, and the floodplain 9 parts are located along its coastal edges relative to the central longitudinal axis of the water supply path 1, and the floodplain 9 parts, in plan, are made in the form of curved segments 11.

To quench the excess kinetic energy of the flow both on the floodplain 9 and in the channel 10 parts there are elements of reinforced roughness 7 made in the form of discretely installed elements with the formation of a gap between them. In addition, a hydraulic phenomenon, called the kinematic effect of the interaction of pressureless flows of the channel 10 and the floodplain 9 parts of the channel cross section, contributes to the suppression of excess flow energy. When the flows of the channel 10 and the floodplain of 9 parts interact in the water supply path 1, a significant decrease in the average and surface flow velocities in the channel of 10 is influenced by the flow of the floodplain 9 parts, at the same time, as a rule, some speed increase.

At the same time, the segmented shape of the floodplain 9 parts fully corresponds to the hydraulic structure of the flow formed inside them - whirlpool currents 15 with a vertical axis of rotation, which are formed during the interaction of the main channel 10 flow and the water flow rate of the floodplain (floodplain) part 9. Part of its kinetic energy the channel 10 spends on the rotation of the volumes of water located on the floodplain 9 parts of the water supply path 1, while a flow with a direction of speed is formed in the curved segments 11 the flow direction of the main flow portion of river bed 10, which increases the work of the main flow and improves the efficiency quench the excess kinetic energy of the water flow.

The presence of natural vegetation in the floodplain 9 sites (Figs. 7-16) creates the opportunity for spawning of phytophilic fish, spawning eggs on the surface of aquatic vegetation, while the efficiency of the spawning process, under conditions of warmer horizons of the floodplain 9 parts, only increases. In addition, due to the smaller depth of water in the floodplain of 9 sites, the flow has a temperature higher than in the channel 10 sites, which also contributes to the selection by fish of both the movement zones along the length of the water supply path 1 and the places for spawning.

A possible embodiment of the floodplain 9 parts located along the length of the water supply path 1 of the channel symmetrically relative to its longitudinal axis (Fig. 17). In this embodiment, the channel 10 flow is actively involved, which, tangentially at the interface between the two types of flows, interacts with the masses of water located in the floodplain 9 areas.

A possible embodiment of the floodplain 9 parts located along the length of the water supply path 1 of the channel asymmetrically relative to its longitudinal axis (figure 1). In this version, the effect of meandering the channel 10 stream is actively used, which at the same time still spends part of its kinetic energy on the rotation of the masses of water located in 15 swirling areas formed in the floodplain 9 sites.

A possible embodiment of the bottom of the floodplain 9 parts located at the same elevation (Fig. 4, 8, 11, 18, 22), which allows you to create equally probable conditions for spawning of fish on the floodplain 9 parts. In particular, the same water depth in the floodplain 9 parts provides a flow with the same water temperature, the value of which is higher than the water temperature in the channel 10 of the water supply path 1.

A possible embodiment of the bottom of the floodplain 9 parts, located at the same elevation, which allows you to create different conditions for spawning fish in the floodplain 9 parts. In particular, the different water depths in the floodplain 9 parts provide a stream with different water temperatures there, which expands the opportunities for migrants to spawn inside the water supply path 1.

In addition, different bottom marks of the floodplain 9 parts dictate the presence of different volumes of liquid in these areas, and this moment forces the main channel 10 to intensify the meandering effect. This is a consequence of the uneven cost of the main stream for the rotation of the masses of water flows of the floodplain 9 parts with different volumes. The overall effect of quenching the kinetic energy of the water stream increases.

A possible embodiment of the elements of enhanced roughness 7, placed in a checkerboard pattern, which improves the overall effect of quenching the kinetic energy of the flow in the bottom horizons.

A possible embodiment of reinforced roughness elements 7 is made of natural material, for example, boulders 12 (Figs. 32 and 33), which makes it possible to form a fish-spawning channel that is as close as possible to the flow conditions in natural river streams. In addition, the use of natural building material reduces the overall cost of building the canal and its operation.

A possible embodiment of the elements of enhanced roughness 7 located at the bottom of the channel 10 of the channel in the form of rolls 13 over the entire width of the bottom of the channel 10 of the channel (Figs. 26, 28 and 29), which improves the efficiency of quenching the kinetic energy of the stream in the bottom horizons. In addition, the presence of transversely arranged elements of enhanced roughness 7 allows the formation of rifts 13 that occur in a natural river flow, which also brings the design of the fish-spawning channel closer to the flow conditions in natural river streams, which are the natural habitat of fish.

A possible embodiment of the elements of enhanced roughness 7 located at the bottom of the channel 10 of the channel, in the form of rolls 13, installed not over the entire width of the bottom of the channel 10 of the channel (Figs. 27, 30, 31, 32), which allows the formation of bottom swimming inlets 14 This arrangement is most favorable for the movement of bottom fish species, such as sturgeons.

The location of the rifts 13 with their adjoining to the left, then to the right side makes it possible to form bottom swimming inlets 14 with alternating them along the length of the water supply path 1 relative to its central longitudinal axis, while even bottom swimming inlets 14 are adjacent to the right side of the channel, and the odd ones to the left (Figs. 27, 30, 31, 32). This arrangement provides equiprobable conditions for the movement of bottom fish along the length of the water supply path 1.

Information sources

1. USSR author's certificate No. 1562397, "Fishery and spawning canal." IPC E 02 В 8/08, Skura V.N., Sukalo G.M., Anokhin A.M., Chistyakov A.A., Guyumdzhibashyan A.G., Anikin B.C., BI No. 17, 1990.

2. Certificate for utility model No. 13806, "Fishery and spawning channel." IPC E 02 B 8/08, Skorobogatov M.A., Lupandin A.I., Pavlov D.S., Barekyan A.Sh., Gorbasheva BC, Reshetov A.P., Skorobogatov A.M., BI No. 15 , 2000.

Claims (13)

1. The method of quenching the kinetic energy of a stream in a fish-spawning canal, which consists in passing a working flow of water through a water supply path, the cross section of which is formed in a polygonal shape with the formation of channel and floodplain parts, at the bottom of which there are elements of enhanced roughness and natural vegetation, characterized by that the bulk of the flow rate is passed through the channel part of the water supply path, which interacts with the rest of the flow rate flowing at floodplain s water-conducting path formed on the convex portion of the channel banks of the river bed, while on flood parts form secondary eddy currents with the vertical axis of rotation, in which the flow direction opposite the flow direction of the primary mass flow, flowing through the bed part of the water-path. 2. Fishery and spawning canal, including a water supply path, the head of which is connected to the upper pool of the hydroelectric facility, and the mouth part is connected to the lower pool, made in the form of a channel with a cross-section of a polygonal shape, reinforced roughness elements and natural vegetation, belt-wise located on the floodplain and channel parts of the channel cross section, characterized in that the channel of the water supply path is made in length with various variants of the cross section, which alternate one after another, while the channel The second part of the channel located along its central longitudinal axis, and the flood portion disposed along its edges shore relative to the central longitudinal axis of the water-path, the flood side in terms are in the form of curvilinear segments. 3. The channel according to claim 2, characterized in that the floodplain parts are located along the length of the water supply path of the channel symmetrically with respect to its longitudinal axis. 4. The channel according to claim 2, characterized in that the floodplain parts are located along the length of the water supply path of the channel asymmetrically relative to its longitudinal axis. 5. The channel according to any one of paragraphs. 2 to 4, characterized in that the bottom of the floodplain parts is located at the same elevation. 6. Channel according to any one of paragraphs. 2 to 4, characterized in that the bottom of the floodplain parts is located at different altitudes. 7. Channel according to any one of paragraphs. 2 to 4, characterized in that the natural vegetation is located on the floodplain. 8. The channel according to any one of paragraphs. 2 to 4, characterized in that the elements of enhanced roughness located at the bottom of the channel part of the channel are made in the form of discretely placed elements with the formation of a gap between them. 9. The channel according to claim 8, characterized in that the elements of enhanced roughness are placed in a checkerboard pattern. 10. The channel according to claim 8, characterized in that the elements of enhanced roughness are made of natural material, for example, boulders. 11. Channel according to any one of paragraphs. 2 to 4, characterized in that the elements of enhanced roughness located at the bottom of the channel part of the channel are made in the form of rolls over the entire width of the bottom of the channel part of the channel. 12. The channel according to any one of paragraphs. 2 to 4, characterized in that the elements of enhanced roughness located at the bottom of the channel channel are made in the form of rifts not over the entire width of the channel channel bottom with the formation of bottom swimming holes. 13. The channel according to claim 12, characterized in that the bottom swimming inlets are formed by alternating them along the length of the water supply path relative to its central longitudinal axis, while even bottom swimming inlets are adjacent to the right side of the channel, and odd holes to the left.

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