A method for ecological restoration of a small and medium-sized river channel

Abstract

The present application relates to a kind of small and medium-sized river water bottom system ecological restoration method, including bottom mud matrix improvement and module construction and submerged plant planting, wherein bottom mud matrix improvement and module construction include: stripping bottom mud→laying geotextile→burying air pipe→preprocessing bottom mud backfilling→planting mycorrhizal plants and harvesting→throwing into polyphosphorus bacteria→laying stone cage net and stone cage net box.The present application includes the improvement of bottom mud matrix, river bottom module construction, underwater forest module planting and so on multiple aspects, combines river bottom mud matrix improvement and submerged plant planting two aspects closely, complement each other, promote each other, fundamentally solves river water ecological pollution problem using biological measures and engineering measures.

Description

Technical Field

[0001] This invention relates to the field of river water pollution control technology, and in particular to a systematic ecological restoration method for the underwater systems of small and medium-sized rivers. Background Technology

[0002] Currently, the main measures for aquatic ecosystem restoration include phytoremediation, bioremediation, physical remediation, chemical remediation, and engineering remediation. Different remediation technologies can complement each other to effectively improve water quality and protect aquatic ecosystems.

[0003] A common aquatic ecological restoration technology is underwater forest technology, which uses submerged plants that can grow rapidly on the seabed to build an underwater forest system. This system absorbs, decomposes, and absorbs the nutrient load of the water, improves water transparency, enhances the underwater landscape, provides a hidden place for aquatic animals such as fish and shrimp to move and spawn, and creates conditions for achieving aquatic ecological balance.

[0004] However, for water bodies that are deep, have high turbidity, low light transmittance, hard sediment, and severe eutrophication, directly planting submerged plants results in low survival rates, difficulty in establishment, and limited restoration effects. Even if they survive for a short time, insufficient sunlight and excessively fast water flow can hinder their normal growth and function, and the decay of stems and leaves can even exacerbate internal pollution in the water. While existing technologies have proposed some methods and structures for constructing underwater forests, these are generally complex and cumbersome to implement directly in practical production. Furthermore, most aquatic ecosystem restoration efforts only emphasize the importance of underwater forests, neglecting sediment improvement or even systematic restoration of riverbed sediments, leading to continuous aggravation of internal pollution in rivers, poor treatment results, and a tendency for recurring problems. Summary of the Invention

[0005] To address the aforementioned water ecological restoration issues, this invention combines engineering and biological measures to propose a systematic underwater ecological restoration method for small and medium-sized rivers. This method fully integrates sediment management with underwater forest construction, ensuring that the two are closely linked and mutually reinforcing, thereby jointly improving the quality of the water ecosystem. Moreover, the underwater forest construction method is simple to implement and easy to apply in practice.

[0006] To achieve the above objectives, the present invention provides a method for systematic ecological restoration of the underwater system in small and medium-sized rivers, comprising the following steps:

[0007] A. Remove 15-20cm of untreated bottom mud from the riverbed and lay a layer of geotextile at the bottom of the river. Install ventilation pipes on the geotextile every 5-15m perpendicular to the river.

[0008] B. The stripped bottom mud is micro-treated, naturally dried and crushed, and animal and plant remains are removed. Sand or gravel is mixed into the micro-treated bottom mud for pretreatment. The bottom mud is divided into two parts: the first pre-treated bottom mud and the second pre-treated bottom mud, which are stirred evenly separately for later use. The first pre-treated bottom mud is composed of bottom mud and sand / gravel in a volume ratio of (2-3):1, and the second pre-treated bottom mud is composed of bottom mud and sand / gravel in a volume ratio of (5-6):1.

[0009] C. Lay a layer of first pretreated sediment parallel to the surface of the vent pipe. Lay a 2-3cm thick layer of sand and gravel on top of the first pretreated sediment. Then, in the direction perpendicular to the river channel, cross the second pretreated sediment and the first pretreated sediment with a basic coverage width of 0.5m on top of the sand and gravel layer. The first pretreated sediment and the second pretreated sediment on top of the sand and gravel layer are separated by PVC baffles.

[0010] D. Mix mycorrhizal fungi and plantain seeds at a ratio of 15g / m 2 and 20g / m 2 The standard is evenly mixed and evenly spread onto the surface of the second pretreated substrate. Then, a 2-3 cm thick layer of the first pretreated substrate is placed on the surface of the first and second pretreated substrates respectively, and leveled. After that, water is applied every 3-5 days for micro-irrigation. After germination, the PVC baffle is removed.

[0011] E. After the plantain has grown for 2-3 months, remove it by the roots, turn over and level the top layer of soil, remove the remaining roots, and dilute the polyphosphate inoculant with water at a volume ratio of 1:10 to obtain the inoculant solution, and spray it evenly on the surface of the soil.

[0012] F. Lay a layer of gabion mesh on the surface of the bottom sediment. Use gabion mesh boxes to form an open stone barrier grid on the gabion mesh. Splice along the long side. Each group consists of 3 to 5 gabion mesh boxes. Set up a group of gabion mesh boxes every 3 to 5 meters on both sides of the river perpendicular to the river channel. Leave a channel at least 2 to 3 meters wide in the middle of the river channel. Place several porous bacteria houses inside the gabion mesh boxes to establish a nitrification system.

[0013] G. Several square basic planting units are set up at the bottom of the river channel. Each basic planting unit includes a cylindrical planting chamber connected to the gabion mesh at the bottom of the river channel and an outer frame structure. Submerged plants are planted in the planting chamber. The selected submerged plants are Vallisneria natans and Potamogeton malaianus, with a planting density of 50-80 Vallisneria natans plants / m². 2 Potamogeton malaianus 30-50 plants / m 2 .

[0014] H. In the early stage of submerged plant growth, the water level should be controlled at a height of about 0.5m. After planting, replant in time. When the submerged plants grow to a height close to the height of the gabion net, gradually increase the water level to the normal water level.

[0015] Preferably, the vent pipe is a semi-cylinder with a diameter of 10cm and a downward-facing plane, and the side surface of the vent pipe is provided with several 2-3mm ventilation holes and wrapped with geotextile.

[0016] Preferably, a cylindrical ventilation channel with a diameter of 3-5 cm is provided at the top of the ventilation pipe. The cylindrical ventilation channel is filled with a geotextile structure wrapped with sand and gravel, and the cylindrical ventilation channel protrudes 1-2 cm from the horizontal position of the ventilation pipe.

[0017] Preferably, the top of the first pretreated sediment is higher than the surface of the vent pipe and lower than the upper plane of the vent channel.

[0018] Preferably, the sand and gravel particles in the sand and gravel layer have a diameter of 0.1 to 0.15 cm, and the mesh size of the gabion mesh is 8 to 10 cm.

[0019] Preferably, the porous bacterial house is made of ceramic material. Nitrifying bacteria and water are mixed at a weight ratio of 1:(30~45), and the porous bacterial house is immersed in the nitrifying bacteria solution for 24 hours. After that, it is placed in a dark place inside a gabion cage.

[0020] Preferably, the planting chamber is an open cylinder with a diameter of 6-8cm and a height of 8-12cm, made of PVC, and the surface of the planting chamber is provided with ventilation holes and covered with geomembrane.

[0021] Preferably, the frame structure is a square PVC board with the edges of the sides folded inwards and ventilation holes on the side.

[0022] Preferably, the frame structure has a circular planting hole with a diameter smaller than that of the planting chamber, and a ring of inward protrusions below the planting hole, which can be embedded in the planting chamber and connected to it.

[0023] Preferably, the planting steps of the submerged plant include: first, laying a 2cm thick layer of second pre-treated bottom mud at the bottom of the planting chamber, then adding a 2-4cm thick layer of first pre-treated bottom mud, planting the roots of the submerged plant into the planting chamber and adding mycorrhizal fungi, then covering the roots with the first pre-treated bottom mud and filling the planting chamber, and finally covering the planting hole with geotextile.

[0024] Based on the above technical solution, the advantages of the present invention are:

[0025] The underwater systematic ecological restoration method for small and medium-sized rivers of the present invention includes multiple aspects such as bottom sediment substrate improvement, riverbed module construction, and underwater forest module planting, providing a more systematic and comprehensive solution for river water ecological restoration and management.

[0026] This invention closely integrates riverbed sediment substrate improvement with submerged plant planting, complementing and promoting each other, and fundamentally solving the problem of river water ecological pollution by using biological and engineering measures. Attached Figure Description

[0027] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0028] Figure 1 A top-view schematic diagram of the ventilation pipe network at the bottom of the river channel;

[0029] Figure 2 A schematic diagram of the cross-sectional structure of the aeration network and sediment improvement at the bottom of the river channel;

[0030] Figure 3 A top-view diagram of the open stone barrier grid structure at the bottom of the river channel;

[0031] Figure 4 This is a schematic diagram of the cross-sectional structure of a basic planting unit. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] This invention provides a systematic ecological restoration method for the underwater systems of small and medium-sized rivers, such as... Figures 1-4 As shown, a preferred embodiment of the present invention is illustrated.

[0034] The process of improving the bottom sediment matrix and constructing modules includes: stripping the bottom sediment → laying geotextile → burying ventilation pipes → pre-treating the bottom sediment and backfilling → planting mycorrhizal plants and harvesting → introducing polyphosphate bacteria → laying gabion nets and gabion boxes.

[0035] Remove 15-20cm of untreated bottom sediment from the riverbed and lay a layer of geotextile 1 at the bottom of the river to prevent pollutants in the untreated sediment from migrating upwards. For example... Figure 1 As shown, ventilation pipes 2 are installed on the geotextile 1 every 5-15m perpendicular to the river channel. Each ventilation pipe 2 is a 10cm diameter, flat-down semi-cylinder. Several 2-3mm ventilation pores are provided on the side surface of the ventilation pipe 2, which are then wrapped with geotextile to prevent clogging. A cylindrical ventilation channel 3 with a diameter of 3-5cm is installed at the top of the ventilation pipe 2. The cylindrical ventilation channel 3 is filled with a geotextile structure containing sand and gravel. The cylindrical ventilation channel 3 protrudes 1-2cm from the horizontal position of the ventilation pipe 2.

[0036] The oxygenation of the bottom sediment and water body through the ventilation pipes on the top and the ventilation holes on the side can increase the oxygen content of the bottom sediment and bottom water body, strengthen the activity of aerobic microorganisms, promote the degradation of organic pollutants in the bottom sediment through the metabolic process of microorganisms, and gradually form an inorganic bottom sediment cover layer to block endogenous pollution.

[0037] The stripped bottom mud is micro-treated, naturally dried and crushed, and animal and plant remains are removed. Sand or gravel is mixed into the micro-treated bottom mud for pretreatment. The bottom mud is divided into two parts: the first pretreated bottom mud 4-1 and the second pretreated bottom mud 4-2, which are stirred evenly for later use. The first pretreated bottom mud 4-1 is composed of bottom mud and sand / gravel in a volume ratio of (2-3):1, and the second pretreated bottom mud 4-2 is composed of bottom mud and sand / gravel in a volume ratio of (5-6):1.

[0038] like Figure 2 As shown, a layer of first pretreated sediment 4-1 is laid parallel to the surface of the vent pipe 2. A 2-3 cm thick layer of sand and gravel 5 is then laid on top of the first pretreated sediment 4-1, with a particle size of 0.1-0.15 cm. Next, in a perpendicular direction to the river channel, the second pretreated sediment 4-2 and the first pretreated sediment 4-1 are laid alternately on top of the sand and gravel layer 5 in units with a coverage width of 0.5 m. A PVC baffle separates the first pretreated sediment 4-1 and the second pretreated sediment 4-2 above the sand and gravel layer 5. The sediment coverage thickness is 5-8 cm for each layer.

[0039] Mix mycorrhizal fungus 12 with plantain seeds 6 at a ratio of 15g / m³ 2 and 20g / m 2 The mixture is then evenly mixed according to standard specifications and spread evenly onto the surface of the second pretreated substrate 4-2. A 2-3 cm thick layer of the first pretreated substrate 4-1 is then placed over both the first and second pretreated substrates 4-1, and the surface is leveled. Watering is then applied every 3-5 days. After germination, the PVC baffle is removed. Watering can be done as needed, watering only when the soil is dry. The plantain 7 is removed completely after 2-3 months of growth, including the roots.

[0040] Since the roots of plantain mainly grow in the second pre-treated sediment (4-2), which has a sandy texture, it facilitates root removal and minimizes the burden on the sediment caused by subsequent root humification, thus preventing eutrophication. Simultaneously, mycorrhizal fungi infect the plantain roots, forming a vast mycelial network that extends to every corner of the sediment. This fully activates and utilizes the nitrogen and phosphorus in the sediment to provide nutrients for the host plant, thereby reducing the nutrient concentration in the sediment. Furthermore, the extensive mycelial network can absorb and remediate heavy metals and toxic organic matter remaining in the sediment, improving sediment pollution and laying the foundation for subsequent submerged plant cultivation. This enhances the resistance and tolerance of aquatic plants and increases their survival rate.

[0041] The improvement and backfilling of sediment substrate has enabled the restoration and utilization of eutrophic sediment, solving the previous problem of having nowhere to dispose of sediment after dredging. This method involves improving and backfilling the sediment substrate at the bottom of the river, combined with measures such as laying aeration pipes for oxygenation and mycorrhizal fungi restoration to achieve systematic treatment of the sediment. This serves as a high-quality growth substrate for subsequent submerged plants, thus achieving the sustainability of the river's ecology.

[0042] After removing the plantain roots, the top layer of soil is re-tilled and leveled, and any remaining roots are removed. The polyphosphate-accumulating microbial agent is diluted with water at a 1:10 volume ratio to obtain a bacterial solution, which is then evenly sprayed onto the surface of the soil. Polyphosphate-accumulating microorganisms are microorganisms that can accumulate both polyphosphates and polyhydroxyalkanoates to meet their growth needs. They exhibit anaerobic phosphorus release and aerobic (or anoxic) superphosphate uptake characteristics, significantly reducing phosphorus concentration during aerobic or anoxic phases, ultimately achieving phosphorus removal.

[0043] like Figure 3 As shown, a layer of gabion mesh 16 with an 8-10cm mesh size is laid on the surface of the bottom sediment, which can provide some fixation for the sediment. Open gabion grids 9 are formed on the gabion mesh 16 using 0.5m×1m×0.5m gabion boxes 8, spliced ​​along the long side, with 3-5 gabion boxes 8 forming a group. A group of gabion boxes 8 is staggered every 3-5m on both sides of the river perpendicular to the river channel, leaving a passage at least 2-3m wide in the middle of the river channel to avoid affecting flood control and drainage.

[0044] Laying gabion nets at the bottom of the river channel can protect and stabilize the riverbed sediment, reduce the erosion of the sediment by the water flow, and maintain a relatively stable terrain; at the same time, it can also fix the planting chambers for submerged plants.

[0045] The gabion cages 8 should be placed away from the air vents as much as possible. The gabion cages 8 divide the riverbed into several open stone barrier grids 9. Submerged plants planted under this structure can reduce the water flow velocity to a certain extent, which can reduce the disturbance of the bottom sediment by the water flow, reduce the exchange of pollutants between the bottom sediment and the water, and provide a relatively stable growth environment for the submerged plants in the early stage of transplantation, improve the survival rate, and facilitate the formation of underwater forests.

[0046] Several porous bacterial houses, made of ceramic, are placed inside the gabion cage 8. Nitrifying bacteria and water are mixed at a weight ratio of 1:30-45. The porous bacterial houses are then immersed in the nitrifying bacteria solution for 24 hours. Afterward, the mixture is placed inside the gabion cage in a dark location to establish a nitrification system. The establishment of the nitrification system can decompose ammonia nitrogen compounds in polluted water, reducing eutrophication and the toxicity of ammonia nitrogen to submerged plants, fish, and other aquatic organisms. At the same time, the combination of porous bacterial houses and gabion cages further satisfies the requirement of a dark growing and living environment for nitrifying bacteria, without affecting the high light requirements of submerged plants.

[0047] The microbial combination of "mycorrhizal bacteria + polyphosphate-accumulating microorganisms + nitrifying bacteria" plays a role in different aspects of sediment treatment and water supply, targeting different nutrients. In the early stage, mycorrhizal bacteria remove most of the nitrogen, phosphorus, heavy metals, and toxic organic matter from the sediment. Polyphosphate-accumulating microorganisms remove phosphorus from the sediment during the later stages of water supply, compensating for the disadvantages of mycorrhizal bacteria in the water and providing some nutrients for submerged plants. Nitrifying bacteria decompose ammonia nitrogen compounds in polluted water, mitigating eutrophication and reducing the toxicity of ammonia nitrogen to submerged plants, fish, and other aquatic organisms.

[0048] The three microbial agents work together in coordination to target different pollutants at different stages. Each one is indispensable, and the removal rate of pollutants is greatly improved compared with a single microorganism, thus curbing the formation and accumulation of river pollution to the greatest extent.

[0049] Several square basic planting units 10 are set at the bottom of the river channel. The side length of each basic planting unit 10 varies from 0.8 to 1m. Each basic planting unit 10 is arranged regularly with a spacing of 3 to 5cm between them. The basic planting unit 10 mainly consists of two parts: a cylindrical planting chamber 11 connected to the gabion mesh 16 at the bottom of the river channel and a frame structure 14. Both of them work together to plant and fix submerged plants. The cylindrical planting chamber 11 is fixed to the gabion mesh 16. It is an open cylinder with a diameter of 6 to 8cm and a height of 8 to 2cm. It is made of PVC and has several ventilation holes on its surface. It is wrapped with a thin geomembrane that is permeable to water and air.

[0050] The frame structure 14 is a square PVC board with the edges of the sides turned inward and the height is lower than that of the planting chamber. Ventilation holes are provided on the side. The square frame structure has circular planting holes 15 with a diameter slightly smaller than that of the planting chamber distributed upward. There is a ring of inward protrusions below the planting holes 15, which can be embedded in the planting chamber 11 and connected to the planting chamber 11.

[0051] Submerged plants 13 are planted in the planting chamber 11 through the planting hole 15. The submerged plants 13 selected are Vallisneria natans and Potamogeton malaianus, with a planting density of 50-80 Vallisneria natans plants / m². 2 Potamogeton malaianus 30-50 plants / m 2 The number and location of planting chambers 11 and planting holes 15 within each basic planting unit 10 are determined according to the planting density of submerged plants 13, which is flexible and convenient, and generally 8 to 12 are evenly distributed.

[0052] Preferably, the planting steps of the submerged plant 13 include: first, laying a 2cm thick layer of second pretreated bottom mud 4-2 at the bottom of the planting chamber 11, then adding a 2-4cm thick layer of first pretreated bottom mud 4-1, planting the roots of the submerged plant 13 into the planting chamber 11 and adding mycorrhizal fungi, then covering the roots with the first pretreated bottom mud 4-1 and filling the planting chamber 11, and finally covering the planting hole 15 with geotextile.

[0053] In the early stages of submerged plant growth, the water level should be maintained at approximately 0.5 meters to ensure sufficient sunlight, allowing the plant roots to establish themselves in the planting area and eventually take root in the riverbed sediment. Any submerged plants that fail to survive during this process should be replanted promptly. Once the submerged plants have grown to a height close to that of the gabion mesh, the water level can be gradually increased to the normal level.

[0054] This planting method provides a relatively stable growth environment and sufficient light for the initial transplantation of submerged plants, reducing the impact of factors such as fast water flow and insufficient light on the initial establishment of submerged plants. At the same time, this planting structure also facilitates the timely retrieval of submerged plant debris, preventing it from sinking to the bottom of the river and causing the release of organic matter, nitrogen, and phosphorus, which would exacerbate endogenous pollution.

[0055] The present invention provides a systematic ecological restoration method for the underwater systems of small and medium-sized rivers, encompassing multiple aspects such as sediment substrate improvement, riverbed module construction, and underwater forest module planting. This provides a more comprehensive and systematic solution for river water ecological restoration and management. The invention closely integrates riverbed sediment substrate improvement with submerged plant planting, allowing them to complement and promote each other. It utilizes both biological and engineering measures to fundamentally address river water ecological pollution problems.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for systematic ecological restoration of the underwater system in small and medium-sized rivers, characterized in that: Includes the following steps: A. Remove 15-20cm of untreated bottom mud from the riverbed and lay a layer of geotextile (1) on the bottom of the river. Install ventilation pipes (2) on the geotextile (1) every 5-15m perpendicular to the river. B. The stripped bottom mud is micro-treated, naturally dried and crushed, and animal and plant remains are removed. Sand or gravel is mixed into the micro-treated bottom mud for pretreatment. The bottom mud is divided into two parts: the first pre-treated bottom mud (4-1) and the second pre-treated bottom mud (4-2), which are stirred evenly for later use. The first pre-treated bottom mud (4-1) is composed of bottom mud and sand / gravel in a volume ratio of (2-3):1, and the second pre-treated bottom mud (4-2) is composed of bottom mud and sand / gravel in a volume ratio of (5-6):

1. C. Lay a layer of first pretreated bottom mud (4-1) parallel to the surface of the ventilation pipe (2), and lay a layer of sand and gravel (5) 2-3cm thick on top of the first pretreated bottom mud (4-1). Then, in the direction perpendicular to the river channel, cross the second pretreated bottom mud (4-2) and the first pretreated bottom mud (4-1) with a basic unit of 0.5m coverage width on top of the sand and gravel layer (5), and separate the first pretreated bottom mud (4-1) and the second pretreated bottom mud (4-2) on top of the sand and gravel layer (5) with PVC baffles. D. Mix mycorrhizal fungi (12) with plantain seeds (6) at a ratio of 15g / m 2 and 20g / m 2 Mix the standard evenly and spread it evenly on the surface of the second pretreated substrate (4-2). Then cover the surface of the first pretreated substrate (4-1) and the second pretreated substrate (4-2) with a thickness of 2-3 cm. Level it and then water it every 3-5 days. After germination, remove the PVC baffle. E. After the plantain (7) has grown for 2-3 months, remove it by the roots, turn over and level the surface mud, remove the remaining roots, and dilute the polyphosphate fungicide with water at a volume ratio of 1:10 to obtain the fungal solution, and spray it evenly on the surface of the mud. F. A layer of gabion mesh (16) is laid on the surface of the bottom mud. An open stone barrier grid (9) is formed on the gabion mesh (16) using gabion boxes (8). The gabion boxes (8) are spliced ​​along the long side. Every 3 to 5 gabion boxes (8) form a group. A group of gabion boxes is set up every 3 to 5 m on both sides of the river perpendicular to the river channel. A channel at least 2 to 3 m wide is left in the middle of the river channel. Several porous bacterial houses are placed inside the gabion boxes (8) to establish a nitrification system. The porous bacterial houses are made of ceramic material. Nitrifying bacteria and water are mixed at a weight ratio of 1: (30 to 45). The porous bacterial houses are immersed in the nitrifying bacteria solution for 24 hours and then placed in a dark place inside the gabion boxes. G. Set up several square basic planting units (10) at the bottom of the river channel. Each basic planting unit (10) includes a cylindrical planting chamber (11) connected to the gabion net (16) at the bottom of the river channel and an outer frame structure (14). Submerged plants (13) are planted in the planting chamber (11). The submerged plants (13) are selected as Vallisneria natans and Potamogeton malaianus, with a planting density of 50-80 Vallisneria natans plants / m². 2 Potamogeton malaianus 30-50 plants / m 2 ; H. In the early stage of submerged plant (13) growth, the water level should be controlled at a height of about 0.5m. After planting, replant in time. When the height of submerged plant (13) grows close to the height of gabion net (16), gradually increase the water level to the normal water level.

2. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 1, characterized in that: The ventilation pipe (2) is a semi-cylinder with a diameter of 10cm and a downward-facing plane. The side surface of the ventilation pipe (2) is provided with several ventilation holes of 2~3mm and is wrapped with geotextile.

3. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 2, characterized in that: A cylindrical ventilation channel (3) with a diameter of 3-5cm is provided at the top of the ventilation pipe (2). The cylindrical ventilation channel (3) is filled with a geotextile structure wrapped with sand and gravel, and the cylindrical ventilation channel (3) protrudes 1-2cm from the horizontal position of the ventilation pipe (2).

4. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 3, characterized in that: The top of the first pretreated sediment (4-1) is higher than the surface of the vent pipe (2) and lower than the upper plane of the vent channel (3).

5. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 1, characterized in that: The sand and gravel in the sand and gravel layer (5) has a particle size of 0.1 to 0.15 cm, and the mesh size of the gabion net (16) is 8 to 10 cm.

6. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 1, characterized in that: The planting chamber (11) is an open cylinder with a diameter of 6-8cm and a height of 8-12cm. It is made of PVC and has ventilation holes on its surface and is covered with geomembrane.

7. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 1, characterized in that: The frame structure (14) is a square PVC board with the edges of the side length bent inwards downwards. The frame structure (14) has ventilation holes on its side.

8. The method for systematic ecological restoration of the underwater system in small and medium-sized rivers according to claim 7, characterized in that: The frame structure (14) has a circular planting hole (15) with a diameter smaller than that of the planting chamber (11) on its upper surface. There is a ring of inward protrusions below the planting hole (15). The protrusions can be embedded in the planting chamber (11) and connected to the planting chamber (11).

9. The method for systematic underwater ecological restoration of small and medium-sized rivers according to claim 8, characterized in that: The planting steps of the submerged plant (13) include: first, laying a 2cm thick layer of second pre-treated bottom mud (4-2) at the bottom of the planting chamber (11), then adding a 2-4cm thick layer of first pre-treated bottom mud (4-1), planting the roots of the submerged plant (13) into the planting chamber (11) and adding mycorrhizal fungi, then covering the roots with the first pre-treated bottom mud (4-1) and filling the planting chamber (11), and then covering the planting hole (15) with geotextile.

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