DEVICE FOR THE MIGRATION OF AQUARIUM ANIMALS

Description

[0001] The invention relates to a device for the migration of aquatic animals, according to the preamble of claim 1. This device is designed to be arranged in a body of water separated by a barrier into a submerged and an upstream section, and to enable the migration of aquatic animals between the submerged and upstream sections of the body of water. In particular, the invention relates to further developments of the known Denil fish pass.

[0002] The Denil fish pass is a technical fish migration aid with a long tradition. The original form of the Denil fish pass was constructed at the beginning of the 20th century and achieved good results with regard to salmon migration. The operating principle of the Denil fish pass is based on the fact that lamellae, typically placed in a steeply inclined channel, create turbulence. This, in turn, causes a backwater effect in the flowing water, thereby slowing the flow velocities in the migration corridor, particularly in the middle of the current. This effect allows fish to migrate upstream at a significantly steeper gradient and with a considerably smaller space requirement. This aspect provides a significant advantage in terms of area and cost compared to other common fish passage systems, such as slot fish passes, pool fish passes, and bypass channels.

[0003] Document US 1,621,170 discloses a fish ladder, also known as a "pool pass," designed to allow fish to migrate upstream, for example, over a weir in a river. However, this device requires extensive construction work. For instance, the pool cascades must be laboriously excavated and / or concreted alongside the river. These construction measures entail both ecological and economic disadvantages.

[0004] While in a slot pass, a pool pass or a bypass channel the total height is bridged section by section by the series of individual pools, in the Denil fish pass the reduction in height occurs continuously.

[0005] The known formations of the Denil fish pass typically exhibit poor passability for small fish species and juvenile fish stages. This is due, on the one hand, to the high turbulence within the fish pass, which these aquatic animals lack the strength to overcome.

[0006] On the other hand, small fish species, juvenile fish stages and several species of other aquatic animals, including numerous large cyprinids, have a strong bottom-bound relationship, which leads to a potential reduction in the efficiency of conventional Denil fish passes.

[0007] Document EP 3 214 225 A1 discloses a further development of the Denil fish pass, in which plate-shaped lamellae are provided with cutouts that initially taper downwards with straight side edges and then transition into a section with straight, parallel side edges. This arrangement significantly reduces the flow velocity at the bottom by means of the transverse connections of the lamellae near the bottom. However, this lamella design creates turbulence, resulting in a strong upward flow impulse. Sampling of such further developed Denil fish passes revealed that small fish species and bottom-oriented migratory fish are underrepresented. According to the inventor, this is primarily due to the high upward flow velocities and the high turbulent kinetic energy.In previously known Denil fish passes, the upward flow velocities in the direction of a normal to the longitudinal axis of the channel exceed those along the longitudinal axis of the channel. As a result, small fish lose their orientation during passage through the fish pass or drift off course in the turbulence, thus hindering their upstream migration.

[0008] From document AT 520908 A1 or the related patent DE 10 2018 251767 A1, another further development of the Denil fish pass is known, which aims to make the Denil fish pass passable for small fish species, juvenile fish stages, and generally for aquatic animals with a strong substrate dependence. In this embodiment, the bottom of the channel body is provided, at least in sections along its longitudinal axis, with a covering layer of natural substrate and / or debris and has a rib of constant height running along the longitudinal axis. The lamellae, arranged transversely to the longitudinal axis, are formed in two parts, each consisting of a right-hand lamella and a left-hand lamella, which each abut the rib laterally.In addition to the biological advantages of this fish passage, it was also noted that, in order to establish a stable flow velocity profile, it requires significantly higher amounts of water supply than the original Denil fish pass.

[0009] Therefore, there remains a need for an improved ascent aid for aquatic animals with some or all of the following properties: Stabilization of the flow profile of the aquatic animal ascent aid, reduction of flow velocities in the aquatic animal ascent aid, reduction of turbulence in the aquatic animal ascent aid, reduction of the required water flow through the aquatic animal ascent aid, formation of extended resting zones for small fish in the aquatic animal ascent aid.

[0010] The present invention solves the stated problem by providing a device for the migration of aquatic animals with the features of claim 1. Advantageous embodiments of the invention are disclosed in the dependent claims, the description and the drawings.

[0011] The device according to the invention for the migration of aquatic animals comprises at least one channel body with an upstream end and a downstream end, wherein the channel body has a longitudinal axis extending between the upstream end and the downstream end, wherein the bottom of the channel body is provided, at least section by section, along the longitudinal axis of the channel body with a covering layer of natural substrate and / or crushed material, wherein the covering layer has a rib extending substantially along the longitudinal axis, and wherein plate-shaped lamellae are arranged transversely to the longitudinal axis of the channel body. The lamellae have a downwardly open lower cutout, which is bounded at the top by a transverse element. The cross-sectional area of ​​the lower cutout is dimensioned such that the rib of the covering layer can be accommodated in the lower cutout.The upper edge of the transverse element has a contour that slopes towards the center, defining a lower boundary of an upper cutout of the slats extending upwards from the transverse element.

[0012] The downward-sloping contour of the upper edge of the transverse element causes the upper section of the lamella, bounded at the bottom by the transverse element, to taper downwards. The terms "top" and "bottom" refer to the installation position of the lamellae in the device for the migration of aquatic animals. The term "towards the center" refers to the lateral direction of the lamella.

[0013] A uniform flow pattern of the water in the channel body and reduced, symmetrical turbulence result when the contour of the upper edge of the transverse element is symmetrical with respect to a width bisector of the lamella.

[0014] Preferably, the upper edge of the transverse element has a curved contour, at least in sections. The curved contour further reduces turbulence. This positive effect is enhanced if the curved contour of the upper edge of the transverse element consists exclusively of curved sections, i.e., it has no straight sections.

[0015] Due to the simpler manufacturing of the lamellae, alternative lamella designs may be advantageous in which the contour is formed with straight sections, thereby accepting a slightly less favorable water flow pattern in the channel and less reduced turbulence. This design will be considered particularly when the device for the migration of aquatic animals has only a slight gradient or when only small differences in elevation between the upstream and downstream water levels need to be overcome.

[0016] Particularly good results regarding the aforementioned properties of the device for the migration of aquatic animals are achieved when a central section of the curved contour of the upper edge of the transverse element is convex. The term "convex" here is to be understood in the mathematical sense, meaning that the contour lies below any line segment connecting any two of its points.

[0017] The best hydraulic results are achieved when the convex central section is parabolic with the parabola's vertex as the lowest point.

[0018] To further improve the properties of the device according to the invention for the migration of aquatic animals, as defined above, one embodiment provides that concave side sections adjoin the convex central section on both sides, with the concave side sections preferably forming the end sections of the curved contour of the upper edge of the transverse element. However, concave end sections are also advantageous if they adjoin straight sections of the contour of the upper edge of the transverse element. The term "concave" is to be understood in the mathematical sense, i.e., that the contour lies above each connecting line segment between any two of its points.

[0019] If the transverse element is designed as an independent, preferably replaceable component, conventional Denil fish passes can be retrofitted according to the invention using such transverse elements, and the lamellae of devices according to the invention for the migration of aquatic animals can be quickly repaired or adapted to a changed water flow.

[0020] For good passability of the device for the migration of aquatic animals for small fish and bottom-oriented fish species, it is advantageous that the height of the bridge of the cover layer along the longitudinal axis of the channel body is essentially constant.

[0021] The invention will now be explained in more detail with reference to exemplary embodiments and the drawings. Figs. 1 An oblique view from above shows a first exemplary embodiment of a device according to the invention for the migration of aquatic animals. Figs. 2The device according to the invention is shown in a longitudinal section along the longitudinal axis. Figs. 1 . Figs. 3 The front view shows a lamella according to the device according to the invention for the migration of aquatic animals. Figs. 4 The front view shows a lamella that is commonly used in the original Denil fish pass according to the state of the art. Figs. 5 The front view shows a lamella of the modified Denil fish pass according to the state of the art. Figs. 6A shows a contour plot of the flow velocity distribution at the lamellae of the original Denil fish pass. Figs. 6B shows a contour plot of the flow velocity distribution at the lamellae of the modified Denil fish pass according to AT 520908. Figs. 6C shows a contour plot of the flow velocity distribution on the lamellae of the device according to the invention for the migration of aquatic animals. Figs. 7Ashows a contour plot of the turbulent kinetic energy at the lamellae of the original Denil fish pass. Figs. 7B shows a contour plot of the turbulent kinetic energy at the lamellae of the modified Denil fish pass according to AT 520908. Figs. 7C shows a contour plot of the turbulent kinetic energy at the lamellae of the device according to the invention for the migration of aquatic animals.

[0022] The Figures 1 and 2 Figure 1 shows a schematic representation of an embodiment of a device 1 according to the invention for the migration of aquatic animals. By means of this device 1, aquatic animals can overcome a barrier in a body of water and migrate from an underwater area 4 to an upper area 5 of the body of water, or vice versa. If the body of water is a flowing body of water, for example a river or a stream, the device 1 is arranged essentially along a flow direction FR.

[0023] The device 1 comprises a channel body 6 with an upstream end 3, which communicates with the upstream water level 5, and with a downstream end 2, which communicates with the downstream water level 4. The channel body 6 extends along a longitudinal axis 8. Consequently, the water flows from the upstream water level 5 essentially along the flow direction FR, i.e., along the longitudinal axis 8, into the downstream water level 4. The device 1 may have end walls 11 in the region of the upstream end 3.

[0024] Furthermore, the device 1 can have a rubber skirt 17 upstream of the upstream end 3 in the area of ​​the bed to counteract undercutting. The rubber skirt 17 can be covered with bed substrate and / or crushed material.

[0025] The device 1 can further have a light shaft 18, wherein the light shaft 18 is arranged laterally to the side of the channel body 6 and wherein a viewing window 19 can be formed inside the light shaft 18 in a side wall 12 of the channel body 6.

[0026] Plate-shaped lamellae 7 are arranged at substantially equal intervals across the longitudinal axis 8 within the channel body 6. These lamellae 7 create a backwater effect for the flowing water, which correspondingly slows the flow velocity. The lamellae 7 are installed at an angle towards the upstream end 3 of the channel body 6. The angle WL, which defines the inclination of the lamellae 7, is, for example, 45 degrees. In some embodiments, the lamellae 7 can also be arranged vertically.

[0027] The bed of the channel body 6 is provided along the longitudinal axis 8, at least in sections, but preferably over the entire length of the channel body 6, with a cover layer 9 made of natural bed substrate or crushed material, or a mixture of natural bed substrate and crushed material. Additionally, crushed aggregate can be incorporated into the cover layer 9. Crushed aggregate is a wear-resistant, crushed gravel and can further reduce the near-bed flow velocity of the watercourse.

[0028] The cover layer 9 has a web 10 extending substantially along the longitudinal axis 8. Below the web 10, the cover layer 9 can extend across the entire width of the channel bed 6, the width being defined as running transversely to the longitudinal axis 8 of the channel bed 6. The web 10 of the cover layer 9 preferably runs centrally with respect to its width. The cross-sectional shape of the cover layer 9, and in particular of the web 10, can be defined by gabions 13, which are basket- or cage-like structures, usually made of metal rods or mesh, in the desired cross-sectional shape. The natural bed substrate, the crushed material, and / or the angular aggregate are secured against erosion and redistribution by the gabions 13. The lamellae 7 can be attached to the gabions 13. If the lamellae 7 rest directly on the channel bed 6, they can be attached there.The lamellae 7 can be attached to the side walls 12 of the channel body 6. However, the lamellae 7 are usually guided in rails and can be pulled out to simplify maintenance of the fish ladder.

[0029] By introducing crushed material and / or angular gravel into the channel body 6, a continuous interstitial space is provided for aquatic animals, thereby increasing the probability of successful migration and facilitating the upstream migration of macrozoobenthos (gravel-dwelling insect larvae) and bottom-dwelling fish. For aquatic organisms strongly associated with the bottom, this makes the barrier generally surmountable. The bridge 10 is preferably filled, at least predominantly, with crushed material. The bridge 10 can, for example, have a rectangular or trapezoidal cross-section. The height of the bridge 10 of the cover layer 9 is essentially constant along the longitudinal axis 8 of the channel body 6.

[0030] Figs. 3Figure 1 shows a front view of a lamella 7 according to the device 1 according to the invention for the migration of aquatic animals. The lamella 7 is plate-shaped and is arranged in the device 1 transversely to the longitudinal axis 8 of the channel body 6. The lamella 7 has a downwardly open lower cutout 22, which is bounded at the top by a transverse element 20. The cross-sectional area of ​​the lower cutout 22 is dimensioned such that the web 10 of the cover layer 9 can be received in the lower cutout 22. The upper edge of the transverse element 20 has a contour 21 that slopes downwards towards the center of the channel from both sides, defining a lower boundary of an upper cutout 23 of the lamella that extends upwards from the transverse element 20. In the present embodiment of the invention, the contour 21 is designed as a curved contour. The contour 21 of the upper edge of the transverse element 20 is symmetrical with respect to a width bisector 24 of the lamella.In the illustrated embodiment of the invention, the contour 21 of the upper edge of the transverse element 20 consists of curved sections along its entire length. A central section 21A of the curved contour 21 of the upper edge of the transverse element 20, i.e., the section located centrally with respect to the bisector 24 of the width, is convex. More precisely, in this embodiment of the invention, the convex central section 21A is parabolic with the vertex S of the parabola as its lowest point, such that the parabolic central section 21A extends upwards symmetrically with respect to the bisector 24 of the width. That is, the bisector 24 simultaneously represents the axis of the parabola. Concave side sections 21B and 21C adjoin the convex central section 21A of the curved contour 21 on both sides. These two concave side sections 21B, 21C form the end sections of the curved contour 21 of the upper edge of the transverse element 20, i.e.The concave side sections 21B, 21C open into the side walls of the upper cutout 23. The upper cutout 23 of the lamella is open at the top. As an alternative to the curved contour 21, although less preferred, a contour with straight sections can be provided, which in its simplest form can be implemented as a V-shaped cutout. As mentioned at the outset, however, such an embodiment exhibits inferior hydraulic properties compared to a curved contour.

[0031] In the illustrated embodiment of the lamella 7, the transverse element 20 is designed as an integrated component of the lamella 7. In an alternative embodiment, however, the transverse element 20 can be designed as an independent, preferably replaceable component.

[0032] The advantageous hydraulic properties of the lamella 7 of the device 1 according to the invention for the migration of aquatic animals are compared below with the hydraulic properties of lamellae of the original Denil fish pass and the modified Denil fish pass according to AT 520908. For illustration, see in Figs. 4 The front view shows a lamella 30, which is commonly used in the original Denil fish pass. Figs. 5 The front view shows a two-part lamella 31 of the modified Denil fish pass according to AT 520908.

[0033] The Figures 6A, 6B and 6C Contour plots of the flow velocity distribution at the lamellae 30 of the original Denil fish pass are shown ( Figs. 6A ), on the lamellae 31 of the modified Denil fish pass according to AT 520908 ( Figs. 6B ), and on the lamellae 7 of the device 1 according to the invention for the migration of aquatic animals ( Figs. 6C ).

[0034] The Figures 7A, 7B and 7Cshow contour plots of the turbulent kinetic energy at the lamellae 30 of the original Denil fish pass ( Figs. 7A ), on the lamellae 31 of the modified Denil fish pass according to AT 520908 ( Figs. 7B ), and on the lamellae 7 of the device 1 according to the invention for the migration of aquatic animals ( Figs. 7C ).

[0035] From the contour plots of the Figures 6A, 6B, 6CIt can be seen that the flow velocities in the modified Denil fish pass are significantly higher than in the original Denil fish pass. Furthermore, it is evident that the flow velocities in the device 1 according to the invention for the migration of aquatic animals are also higher in certain sections than in the original Denil fish pass, but significantly lower than in the modified Denil fish pass. Considering the distribution of the flow velocity, it becomes apparent that in the device 1 according to the invention for the migration of aquatic animals, the flow velocity in a region from the curved contour 21 of the transverse element 20 upwards to approximately the midpoint of the height of the upper cutout 23 is similarly low to that of the original Denil fish pass, and only above this point does it exhibit higher values. This lower region is relevant for the upstream migration of small aquatic animals and bottom-dwelling aquatic animals.The flow velocity in the modified Denil fish pass is generally higher than in the device 1 according to the invention for the migration of aquatic animals and than in the original Denil fish pass.

[0036] From the contour plots of the Figures 7A, 7B, 7C It can be seen that the turbulent kinetic energy in the original Denil fish pass is significantly higher than in the modified Denil fish pass and than in the device 1 according to the invention for the migration of aquatic animals.

[0037] In summary, it can be stated that the device 1 according to the invention for the migration of aquatic animals achieves a significant reduction in flow velocities compared to the prior art, while maintaining the low turbulent kinetic energy. The illustration of the turbulent kinetic energy in the original Denil fish pass in Figs. 7AThis also clearly illustrates that the original Denil fish pass exhibits high turbulence near the bottom, which limits its passability for a wide range of species. This problem is completely solved by the present invention. Compared to the modified Denil fish pass, the present invention is characterized by a significant reduction in flow velocity, thus enabling even weaker and smaller aquatic animals to overcome the device 1 for the migration of aquatic animals, even in larger designs.A key achievement of the present invention lies in its hydraulic resilience, so that the fish pass can be expected to function even with reduced water flow, such as during fyke net monitoring (where the fyke net maps are continuously blocked by floating materials such as leaves, thus reducing the flow), which is a standardized method for the biotic testing of fish passage facilities.

Claims

1. A device (1) for the migration of aquatic animals, wherein the device (1) has at least one channel body (6) with an upstream end (3) and with a downstream end (2), wherein the channel body (6) has a longitudinal axis (8) extending between the upstream end (3) and the downstream end (2), wherein the bottom of the channel body (6) is provided, at least in sections along the longitudinal axis (8) of the channel body (6), with a cover layer (9) made of natural bottom substrate and / or debris material, and the cover layer (9) has a ridge (10) running essentially along the longitudinal axis (8), wherein plate-shaped lamellae (7) are arranged in the channel body (6) transversely to the longitudinal axis (8) of the channel body (6), characterized in that the lamellae (7) have a downwardly open lower cut-out (22), which is limited at the top by a transverse element (20), wherein the cross-sectional area of the lower cut-out (22) is dimensioned in such a way that the ridge (10) of the cover layer (9) may be accommodated in the lower cut-out (22), wherein the upper edge of the transverse element (20) has a contour (21), which is inclined towards the centre and defines a lower boundary of an upper cut-out (23) of the lamellae (7) extending upwards from the transverse element (20).

2. A device according to claim 1, characterized in that the contour (21) of the upper edge of the transverse element (20), which is inclined towards the centre, is symmetrical with respect to a bisector (24) of the width of the lamella (7).

3. A device according to claim 1 or 2, characterized in that the contour (21) of the upper edge of the transverse element (20) has a curved course at least in some sections.

4. A device according to claim 3, characterized in that the curved contour (21) of the upper edge of the transverse element (20) consists exclusively of curved sections (21A, 21B, 21C).

5. A device according to claim 3 or 4, characterized in that a central section (21A) of the curved contour (21) of the upper edge of the cross member (20) is configured to be convex.

6. A device according to claim 5, characterized in that the convex central section (21A) is configured to be parabolic with the parabolic vertex (S) as the lowest point.

7. A device according to claim 5 or 6, characterized in that the convex central section (21A) is adjoined on both sides by concave side sections (21B, 21C).

8. A device according to claim 7, characterized in that the concave side sections (21B, 21C) form the end sections of the curved contour (21) of the upper edge of the transverse element (20).

9. A device according to claim 1 or 2, characterized in that the contour of the upper edge of the transverse element (20) has a straight course at least in some sections.

10. A device according to any of the preceding claims, characterized in that the transverse element (20) is configured as an independent, preferably replaceable component.

11. A device according to any of the preceding claims, characterized in that the height of the ridge (10) of the cover layer (9) is substantially constant along the longitudinal axis (8) of the channel body (6).