A system for improving fish microhabitat conditions in a de-watering river section

Abstract

The application discloses a system for improving fish microhabitat conditions in a reduced-dehydration river section, comprising a river-bank unit for returning water to a river channel and a river-bank unit for collecting water in a river channel, the river-bank unit for returning water to a river channel comprises river banks symmetrically arranged relative to a center line of the river channel, the river-bank unit for collecting water in a river channel comprises river banks symmetrically arranged relative to the center line of the river channel, one end of the river bank for returning water to a river channel is used for being connected with a bank slope of a corresponding upstream river channel, the other end is connected with one end of a corresponding river bank for collecting water in a river channel, the horizontal distance between the two ends of the two river banks for returning water to a river channel connected with the bank slope of the corresponding upstream river channel is greater than the horizontal distance between the other ends, the horizontal distance between the two ends of the two river banks for collecting water in a river channel connected with the corresponding river bank for returning water to a river channel is greater than the horizontal distance between the other ends, the top end of the river bank for returning water to a river channel is higher than the top end of the river bank for collecting water in a river channel, and the water side of the river bank for collecting water in a river channel is provided with a plurality of safety channels. The system can improve the water flow conditions of the reduced-dehydration river section, can repair the microhabitat of fish, and provides conditions for the growth and habitat of fish.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ecological environment restoration, and particularly relates to a system for improving fish microhabitat conditions in a reduced water discharge river section. BACKGROUND

[0002] The development potential of small cascade hydropower in China is large. Seasonal rivers in some mountainous areas are affected by the construction of cascade diversion-type power stations. The flow in the downstream river section of the dam is reduced, which changes the physical habitat of the downstream river for the survival and habitation of organisms, mainly in terms of the reduction of river water width, the decrease of river average water depth, and the reduction of river section flow rate. Fish, as the top organism in the food chain of the river ecosystem, is sensitive to changes in the physical habitat conditions of the river. The deterioration of the river flow conditions will gradually affect the habitat of fish.

[0003] Existing researches are mainly focused on the calculation of river ecological flow, and the research on engineering measures for improving fish habitat conditions is relatively lacking. According to the actual engineering implementation, the effect of the measure of discharging ecological flow at the dam for restoring the habitat of the downstream river is not good, and auxiliary engineering measures often need to be arranged at the same time. Common auxiliary engineering measures for river regulation include drop weir, slot, and creation of riparian plant community, etc. However, auxiliary engineering measures often face the problems of serious structure damage and difficult maintenance due to large flood flow and large sediment transport in the river. In order to prevent water erosion, auxiliary engineering measures often use reinforced concrete structures, but such hard structures are not conducive to groundwater exchange, and have poor water permeability and ecology. In addition, the drop weir has a certain water blocking effect on the river, which affects the flow to a certain extent. At present, the implementation of auxiliary engineering measures mainly focuses on improving the flow conditions, and is not combined with the creation of fish habitat. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a system for improving fish microhabitat conditions in a reduced water discharge river section, which can improve the flow conditions in the reduced water discharge river section, and can restore the microhabitat of fish to provide conditions for the growth and habitation of fish.

[0005] The technical scheme adopted by the present application to solve the technical problems is:

[0006] A system for improving fish microhabitat conditions in a degrading river section, comprising a channeling bank unit and a converging bank unit arranged in sequence along the water flow direction, the channeling bank unit comprising channeling banks symmetrically arranged relative to the river center line, the converging bank unit comprising converging banks symmetrically arranged relative to the river center line, one end of the channeling bank being connected to the corresponding upstream river bank slope, the other end being connected to one end of the corresponding converging bank, the horizontal distance between the two ends of the channeling bank connected to the corresponding upstream river bank slope being greater than the horizontal distance between the other two ends, the horizontal distance between the two ends of the converging bank connected to the corresponding channeling bank being greater than the horizontal distance between the other two ends, the top end of the channeling bank being higher than the top end of the converging bank, the top end of the converging bank being higher than the river normal water level, and the water side of the converging bank being provided with multiple refuge channels for fish refuge.

[0007] Further, the downstream side of the converging bank unit is also provided with a releasing bank unit, the releasing bank unit comprising releasing banks symmetrically arranged relative to the river center line, the other end of the converging bank being connected to one end of the corresponding releasing bank, the other end of the releasing bank being connected to the corresponding downstream river bank slope, the horizontal distance between the two ends of the releasing bank connected to the corresponding converging bank being less than the horizontal distance between the other two ends, and the top end of the releasing bank being flush with the river normal water level.

[0008] Further, the channeling bank and the releasing bank are made of the same material, the channeling bank is formed by splicing multiple stone blocks, a first support rod is inserted at the bottom end of each stone block, and the bottom end of the first support rod is inserted into the river bottom.

[0009] Further, the converging bank comprises a positioning net and multiple stones filling the positioning net, multiple second support rods are inserted at the gaps between the stones at the bottom end of the converging bank, the bottom end of each second support rod is inserted into the river bottom, and the width of the upper end of the converging bank is less than the width of the lower end.

[0010] Further, the refuge channel is a refuge pipe, multiple refuge pipes are horizontally inserted into the converging bank at a certain distance from the water side of the converging bank.

[0011] Further, a first boulder community is provided in the upstream area between the two converging banks, the first boulder community comprises two rows of guide stone assemblies, each row of guide stone assemblies comprises multiple guide stones close to the water side of the corresponding converging bank, the extension direction of the multiple guide stones is parallel to the extension direction of the corresponding converging bank, and the top end of the guide stone is higher than the river mud surface height.

[0012] Further, the number of the guide stones is equal to the number of the safety channels, each of the guide stones is arranged close to the corresponding safety channel, and the top end height of the safety channel is higher than the top end height of the corresponding guide stone.

[0013] Further, the area between the two rows of the guide stone assemblies is provided with a plurality of rows of block stone ridges perpendicular to the water flow direction, the block stone ridges comprise a plurality of block stones, the top end height of the block stones is higher than the river channel mud surface height and lower than the top end height of the guide stones at the corresponding positions.

[0014] Further, the top end height of the guide stone at the upstream is higher than the top end height of the guide stone at the downstream, the third support rod is inserted at the bottom end of the guide stone, and the bottom end of the third support rod is inserted into the river bottom; the top end height of the block stone at the upstream is higher than the top end height of the block stone at the downstream, the fourth support rod is inserted at the bottom end of the block stone, and the bottom end of the fourth support rod is inserted into the river bottom.

[0015] Further, the downstream area between the two current collecting river banks is provided with a second boulder community, the second boulder community comprises a center stone block at the river center line, a plurality of edge stone blocks are arranged around the edge of the center stone block, each of the edge stone blocks and the center stone block are connected through a connecting rod, the fifth support rod is inserted at the bottom end of the center stone block, and the bottom end of the fifth support rod is inserted into the river bottom.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The system for improving the micro-habitat conditions of fish in the dehydrated river section of the present application can improve the water flow conditions of the dehydrated river section, repair the micro-habitat of fish, and provide conditions for the growth and habitat of fish. In addition, the top end height of the converging river bank is higher than the top end height of the current collecting river bank, and the top end height of the current collecting river bank is higher than the normal water level of the river channel. Therefore, the top end height of the converging river bank and the current collecting river bank arranged symmetrically on both sides of the river center line changes along the water flow direction, which improves the water flow conditions without affecting the flood discharge and flow of the river channel. Compared with the traditional weir dam, the converging river bank and the current collecting river bank of the present application basically do not block water, continuously improve the micro-habitat conditions of fish in the length range along the water flow direction, do not affect the connection between the upstream and downstream river channels and the upstream migration of fish, and facilitate the safety of fish due to the plurality of safety channels arranged on the water side of the current collecting river bank.

[0018] The application can increase the flow velocity and improve the micro-habitat conditions of fish in the dry season and the high water level period of the river channel, and can form different flow velocity zones by arranging the converging grooves and the flow-recovering grooves symmetrically on both sides of the center line of the river channel, so that the water flow in the upstream river channel converges once when entering the space between the two converging grooves, converges twice when entering the space between the two flow-recovering grooves, and the flow velocity gradually increases along the water flow direction, and the flow velocity reaches the maximum at the downstream end of the two flow-recovering grooves, and the high flow velocity at the downstream end of the two flow-recovering grooves stimulates the fish to swim upstream.

[0019] In the application, the converging grooves are formed by splicing a plurality of stones, and the first supporting rods are inserted at the bottom end of each stone, and the bottom end of the first supporting rods is inserted into the river bottom, the flow-recovering grooves include a positioning net and a plurality of stones filled in the positioning net, and the second supporting rods are inserted at the gaps between the stones at the bottom end of the flow-recovering grooves, and the bottom end of each second supporting rod is inserted into the river bottom, and the width of the upper end of the flow-recovering grooves is smaller than the width of the lower end.

[0020] In the application, one end of the converging grooves is used to connect with the corresponding upstream river bank slope, the downstream side of the flow-recovering groove unit is further provided with a releasing groove unit, the releasing groove unit includes releasing grooves arranged symmetrically with respect to the center line of the river channel, the other end of the flow-recovering groove is connected with one end of the corresponding releasing groove, the other end of the releasing groove is used to connect with the corresponding downstream river bank slope, and the horizontal distance between the two releasing grooves and the corresponding one end of the flow-recovering groove is smaller than the horizontal distance between the two releasing grooves and the other end of the flow-recovering groove, so that the upstream end of the converging grooves is connected with the upstream river bank slope, the downstream end of the converging grooves is connected with the upstream end of the flow-recovering grooves, the downstream end of the flow-recovering grooves is connected with the upstream end of the releasing grooves, and the downstream end of the releasing grooves is connected with the downstream river bank slope, thereby effectively stabilizing the river beach, forming a shoal habitat, being beneficial to the formation of a diverse habitat of the river channel, providing a habitat and a refuge for fish, and creating conditions for the natural succession of aquatic plant communities.

[0021] In the application, the upstream area between the two flow-receiving river embankments is provided with a first boulder community, the first boulder community comprises two rows of guide stone assemblies, each row of guide stone assembly comprises a plurality of guide stones close to the water side of the corresponding flow-receiving river embankment, the extension direction of the plurality of guide stones is parallel to the extension direction of the corresponding flow-receiving river embankment, the top end height of the guide stone is higher than the river channel mud surface height, the area between the two rows of guide stone assemblies is provided with a plurality of rows of block stone ridges perpendicular to the direction of water flow, the block stone ridge comprises a plurality of block stones, the top end height of the block stone is higher than the river channel mud surface height and lower than the top end height of the guide stone at the corresponding position; in this way, through the arrangement of the two rows of guide stone assemblies and the plurality of rows of block stone ridges, a multi-stage water flow can be created, which is beneficial to increase the dissolved oxygen of the river water flow and improve the fish microhabitat. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic view of the top structure of the system for improving the fish microhabitat conditions of the river section with reduced water loss according to the application;

[0023] Figure 2 is a schematic view of the top structure of the system for improving the fish microhabitat conditions of the river section with reduced water loss according to the application; Figure 1 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application;

[0024] Figure 3 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application; Figure 2 is an enlarged schematic view of one of the flow-receiving river embankments in the application;

[0025] Figure 4 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application; Figure 1 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application;

[0026] Figure 5 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application; Figure 1 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application;

[0027] Figure 6 is a schematic view of the side sectional structure of the two flow-receiving river embankments in the application; Figure 5 is an enlarged schematic view of the left flow-receiving river embankment in the application;

[0028] Figure 7 is an enlarged schematic view of the first boulder community in the application; Figure 1 is an enlarged schematic view of the first boulder community in the application;

[0029] Figure 8 is an enlarged schematic view of the second boulder community in the application. Figure 1 is an enlarged schematic view of the second boulder community in the application.

[0030] Explanation of reference numerals in the drawings: 1, homing dike, 11, stone, 12, first support rod, 2, current collecting dike, 21, stone, 22, positioning net, 23, refuge pipeline, 24, second support rod, 3, releasing dike, 4, first boulder community, 41, guide stone, 42, block stone protruding ridge, 421, block stone, 5, second boulder community, 51, center stone, 52, edge stone, 53, connecting rod, 54, fifth support rod, 6, river center line, 7, riverbed surface line, 8, river bank slope. DETAILED DESCRIPTION

[0031] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate the present application, and are not limiting to the present application.

[0032] In the description of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for description purposes and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0035] As Figures 1-8As shown, a system for improving fish microhabitat conditions in a dehydrated river section includes a converging bank unit and a converging downstream bank unit arranged in sequence along the water flow direction, the converging bank unit includes converging banks 1 arranged symmetrically relative to the river center line 6, the converging downstream bank unit includes converging downstream banks 2 arranged symmetrically relative to the river center line 6, one end of the converging bank 1 is connected with the corresponding upstream river bank slope 8, the other end is connected with one end of the corresponding converging downstream bank 2, the horizontal distance between the two converging banks 1 connected with the corresponding upstream river bank slope 8 at one end is greater than the horizontal distance between the other end, the horizontal distance between the two converging downstream banks 2 connected with the corresponding converging bank 1 at one end is greater than the horizontal distance between the other end, the top end height of the converging bank 1 is higher than the top end height of the converging downstream bank 2, the top end height of the converging downstream bank 2 is higher than the river normal water level, the water side of the converging downstream bank 2 is provided with a plurality of refuge channels for fish refuge, wherein the refuge channel is a refuge pipeline 23, a plurality of refuge pipelines 23 are horizontally inserted into the converging downstream bank 2 from the water side of the converging downstream bank 2 at a certain distance, preferably, the refuge pipeline 23 is a circular pipe with a diameter not less than 0.5m, and the end of the refuge pipeline 23 close to the water side of the converging downstream bank 2 is cut to be flush with the surface of the water side of the converging downstream bank 2. Figure 1 A in the formula (1) represents the water flow direction, Figure 2 , Figure 4 and Figure 5 B in the formula (1) represents the river normal water level.

[0036] Since the converging bank unit and the converging downstream bank unit are arranged in sequence along the water flow direction, the horizontal distance between the two converging banks 1 connected with the corresponding upstream river bank slope 8 at one end is greater than the horizontal distance between the other end, the horizontal distance between the two converging downstream banks 2 connected with the corresponding converging bank 1 at one end is greater than the horizontal distance between the other end, which can improve the water flow conditions of the dehydrated river section, repair the microhabitat of fish, and provide conditions for the growth and habitat of fish. In addition, since the top end height of the converging bank 1 is higher than the top end height of the converging downstream bank 2, and the top end height of the converging downstream bank 2 is higher than the river normal water level, the top end height of the converging bank 1 and the converging downstream bank 2 arranged symmetrically on both sides of the river center line 6 changes along the water flow direction, which improves the water flow conditions without affecting the river flood discharge and flow, compared with the traditional river dam, the converging bank 1 and the converging downstream bank 2 of the present application basically do not block water, continuously improve the fish microhabitat conditions within the length range along the water flow direction, do not affect the connection of the upstream and downstream river channels and the upstream migration of fish, and facilitate fish refuge due to the plurality of refuge channels for fish refuge on the water side of the converging downstream bank 2.

[0037] The application can improve the micro-habitat conditions of fish directly by increasing the flow rate during the dry season and the high water level of the normal water period of the river channel, and can form different flow rate zones by arranging the return channel embankment 1 and the flow recovery river embankment 2 symmetrically on both sides of the center line 6 of the river channel along the water flow direction, so that the water flow in the upstream river channel converges once when entering the two return channel embankments 1 and converges twice when entering the two flow recovery river embankments 2, and the flow rate gradually increases along the water flow direction, and the flow rate of the water flow at the downstream end of the two flow recovery river embankments 2 reaches the maximum value, and the high flow rate of the water flow at the downstream end of the two flow recovery river embankments 2 stimulates the fish to swim upstream.

[0038] In one embodiment, the flow recovery river embankment unit downstream side is also provided with a release river embankment unit, the release river embankment unit includes a release river embankment 3 arranged symmetrically relative to the river channel center line 6, the other end of the flow recovery river embankment 2 is connected with one end of the corresponding release river embankment 3, the other end of the release river embankment 3 is used to connect with the corresponding downstream river channel bank slope 8, the horizontal distance between the two release river embankments 3 and one end connected with the corresponding flow recovery river embankment 2 is smaller than the horizontal distance between the other ends, the top end of the release river embankment 3 is flush with the river normal water level, see Figure 1 and 4 . In this way, the upstream end of the return channel embankment 1 is connected with the upstream river channel bank slope 8, the downstream end of the return channel embankment 1 is connected with the upstream end of the flow recovery river embankment 2, the downstream end of the flow recovery river embankment 2 is connected with the upstream end of the release river embankment 3, and the downstream end of the release river embankment 3 is connected with the downstream river channel bank slope 8, thereby effectively stabilizing the river beach, forming a shallow beach habitat, which is conducive to the formation of a diverse habitat of the river channel, and provides a habitat and a refuge for fish, and creates conditions for the natural succession of aquatic plant communities.

[0039] In one embodiment, the material of the return channel embankment 1 is the same as that of the release river embankment 3, the return channel embankment 1 is formed by splicing a plurality of stone blocks 11, a plurality of first support rods 12 are inserted at the bottom end of each stone block 11, and the bottom ends of the first support rods 12 are inserted into the river bottom, see Figure 3 , the flow recovery river embankment 2 includes a positioning net 22 and a plurality of stones 21 filled in the positioning net 22, wherein the positioning net 22 is a wire mesh, a plurality of second support rods 24 are inserted at the gaps of the stones 21 at the bottom end of the flow recovery river embankment 2, the bottom ends of the second support rods 24 are inserted into the river bottom, and the width of the upper end of the flow recovery river embankment 2 is smaller than the width of the lower end, see Figure 6 . In this way, the ecological property, the erosion resistance and the durability of the return channel embankment 1, the flow recovery river embankment 2 and the release river embankment 3 are all good.

[0040] In one embodiment, as Figure 1 , 5As shown in FIGS. 7, the upstream region between the two flow-receiving river embankments 2 is provided with a first boulder colony 4, the first boulder colony 4 includes two rows of guide stone assemblies, each row of guide stone assemblies includes a plurality of guide stones 41 close to the water side of the corresponding flow-receiving river embankment 2, the extension direction of the plurality of guide stones 41 is parallel to the extension direction of the corresponding flow-receiving river embankment 2, the top end of the guide stone 41 is higher than the height of the riverbed, and the region between the two rows of guide stone assemblies is provided with a plurality of rows of block stone ridges 42 perpendicular to the direction of the water flow, the block stone ridge 42 includes a plurality of block stones 421, the top end of the block stone 421 is higher than the height of the riverbed and lower than the top end of the guide stone 41 at the corresponding position; in this way, through the arrangement of the two rows of guide stone assemblies and the plurality of rows of block stone ridges 42, a multi-stage water flow can be created, which is beneficial to increase the dissolved oxygen of the river water flow and improve the fish microhabitat. Preferably, the length of the upstream region along the extension direction of the flow-receiving river embankment 2 accounts for 2 / 3 of the length of the flow-receiving river embankment 2, and preferentially, the horizontal distance between adjacent block stone ridges 42 is 1-2 m, and the top end of the block stone 421 is higher than the height of the riverbed by no less than 0.15 m.

[0041] In one embodiment, the number of guide stones 41 is equal to the number of refuge channels, each guide stone 41 is arranged close to the corresponding refuge channel, and the top end of the refuge channel is higher than the top end of the corresponding guide stone 41; in this way, it is convenient for fish to enter the corresponding refuge channel through the corresponding guide stone 41, and the present application creates a refuge and resting channel for fish by combining the refuge channel and the corresponding guide stone 41 within the range of the flow-receiving river embankment 2, in combination with the habit of fish swimming along the edge and upstream.

[0042] In one embodiment, the top end of the guide stone 41 at the upstream is higher than the top end of the guide stone 41 at the downstream, and the top end of the block stone 421 at the upstream is higher than the top end of the block stone 421 at the downstream, so that the river flood discharge is not affected during the flood season, and the bottom end of the guide stone 41 is inserted with a third support rod, and the bottom end of the fourth support rod is inserted into the riverbed, so that the anti-scouring performance of the guide stone 41 and the block stone 421 is better.

[0043] In one embodiment, as shown in FIGS. 7, Figure 1 and 8As shown, the downstream area between the two flow-converging river embankments 2 is provided with a second boulder colony 5, which includes a central boulder 51 at the center line 6 of the river channel, a plurality of edge boulders 52 around the edge of the central boulder 51, and a horizontal connecting rod 53 connecting each of the edge boulders 52 and the central boulder 51, wherein the connecting rod 53 is a steel pipe, and the bottom end of the central boulder 51 is provided with a fifth support rod 54, and the bottom end of the fifth support rod 54 is inserted into the river bottom. In this way, the second boulder colony 5 can further increase the dissolved oxygen of the river water flow and improve the fish microhabitat. Preferably, the length of the downstream area along the extension direction of the flow-converging river embankment 2 accounts for 1 / 3 of the length of the flow-converging river embankment 2.

[0044] In one embodiment, the ratio of the horizontal distance between the upstream ends of the two flow-converging river embankments 2 to the horizontal distance between the downstream ends is not less than 2, the included angle between the channeling river embankment 1 and the corresponding flow-converging river embankment 2 is controlled to be 135-145°, the inclination angle of the flow-converging river embankment 2 relative to the center line 6 of the river channel is controlled to be 9-12°, the top end height of the channeling river embankment 1 is higher than the normal water level of the river channel by not less than 0.5m, the top end height of the flow-converging river embankment 2 is higher than the normal water level of the river channel by not less than 0.3m, the size of the boulder 11 of the channeling river embankment 1 is not less than 0.8m, the depth of the first support rod 12 inserted into the boulder 11 is not less than 0.4m, the second support rod 24 inserted into the flow-converging river embankment 2 is not less than half of the height of the flow-converging river embankment 2, and the first support rod 12, the second support rod 24, the third support rod, the fourth support rod, and the fifth support rod 54 are all vertical steel pipes.

[0045] The above description is only the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and replacements without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A system for improving fish microhabitat conditions in a degrading river reach, characterized by: The application relates to a river bank structure, which comprises, in the direction of water flow, a converging bank unit and a converging bank unit, the converging bank unit comprises converging banks (1) arranged symmetrically relative to a river center line (6), the converging bank unit comprises converging banks (2) arranged symmetrically relative to the river center line (6), one end of the converging bank (1) is connected with a corresponding upstream river bank slope (8), the other end is connected with one end of the corresponding converging bank (2), the horizontal distance between the two converging banks (1) connected with the corresponding upstream river bank slope (8) is greater than that between the other ends, the horizontal distance between the two converging banks (2) connected with the corresponding converging bank (1) is greater than that between the other ends, the top end of the converging bank (1) is higher than that of the converging bank (2), the top end of the converging bank (2) is higher than the normal water level of the river, and the water side of the converging bank (2) is provided with multiple fish refuge channels.

2. A system for improving fish microhabitat conditions in a degrading river reach according to claim 1, characterised in that: The downstream side of the converging bank unit is also provided with a releasing bank unit, the releasing bank unit comprises releasing banks (3) arranged symmetrically relative to the river center line (6), the other end of the converging bank (2) is connected with one end of the corresponding releasing bank (3), the other end of the releasing bank (3) is connected with a corresponding downstream river bank slope (8), the horizontal distance between the two releasing banks (3) connected with the corresponding converging bank (2) is smaller than that between the other ends, and the top end of the releasing bank (3) is flush with the normal water level of the river.

3. A system for improving fish microhabitat conditions in a degrading river reach according to claim 2, characterised in that: The material of the converging bank (1) and the releasing bank (3) is the same, the converging bank (1) is formed by splicing multiple stone blocks (11), a first supporting rod (12) is arranged at the bottom end of each stone block (11), and the bottom end of the first supporting rod (12) is inserted into the river bottom.

4. The system for improving fish microhabitat conditions in a degrading river reach of claim 2, wherein: The converging bank (2) comprises a positioning net (22) and multiple stones (21) filled in the positioning net (22), multiple second supporting rods (24) are arranged at the gaps between the stones (21) at the bottom end of the converging bank (2), the bottom end of each second supporting rod (24) is inserted into the river bottom, and the width of the upper end of the converging bank (2) is smaller than that of the lower end.

5. A system for improving fish microhabitat conditions in a degrading river reach according to claim 4, characterised in that: The refuge channel is a refuge pipeline (23), multiple refuge pipelines (23) are horizontally inserted into the converging bank (2) at a certain distance from the water side of the converging bank (2).

6. The system for improving fish microhabitat conditions in a degrading river reach of claim 1, wherein: The upstream area between the two converging banks (2) is provided with a first boulder community (4), the first boulder community (4) comprises two rows of guide stone assemblies, each row of guide stone assemblies comprises multiple guide stones (41) close to the water side of the corresponding converging bank (2), the extension direction of the connecting lines of the multiple guide stones (41) is parallel to the extension direction of the corresponding converging bank (2), and the top end of the guide stone (41) is higher than the river mud surface.

7. A system for improving fish microhabitat conditions in a degrading river reach according to claim 6, characterised in that: The number of the guide stones (41) is equal to the number of the safety channels, each of the guide stones (41) is arranged near the corresponding safety channel, and the top end of the safety channel is higher than the top end of the corresponding guide stone (41).

8. The system for improving fish microhabitat conditions in a degrading river reach of claim 6, wherein: The area between the two rows of the guide stone assemblies is provided with a plurality of rows of block stone ridges (42) perpendicular to the water flow direction, the block stone ridges (42) include a plurality of block stones (421), the top end of the block stone (421) is higher than the height of the river channel mud surface and lower than the top end of the guide stone (41) at the corresponding position.

9. A system for improving fish microhabitat conditions in a degrading river reach according to claim 8, characterised in that: The top end of the guide stone (41) at the upstream is higher than the top end of the guide stone (41) at the downstream, the third support rod is inserted at the bottom end of the guide stone (41), and the bottom end of the third support rod is inserted into the river bottom; the top end of the block stone (421) at the upstream is higher than the top end of the block stone (421) at the downstream, the fourth support rod is inserted at the bottom end of the block stone (421), and the bottom end of the fourth support rod is inserted into the river bottom.

10. The system for improving fish microhabitat conditions in a degrading river reach of claim 6, wherein: The downstream area between the two river bank embankments (2) is provided with a second boulder community (5), the second boulder community (5) includes a center stone (51) at the center line (6) of the river channel, a plurality of edge stones (52) are arranged around the edge of the center stone (51), each of the edge stones (52) and the center stone (51) are connected by a connecting rod (53), and the fifth support rod (54) is inserted at the bottom end of the center stone (51), and the bottom end of the fifth support rod (54) is inserted into the river bottom.

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