Urban river bottom animal habitat restoration method

Abstract

This application relates to a method for restoring benthic animal habitats in urban rivers, which falls under the field of urban ecological engineering. The method includes the following steps: S10, Basement Diagnosis and Targeted Restoration: Surveying the elevation, morphology, and structure of the riverbed, assessing the degree of sediment pollution, and performing targeted restoration of polluted areas; S20, Hydrological Simulation and Optimized Control: Constructing a river hydrodynamic model based on the riverbed survey results, determining the ecological water replenishment required to maintain ecological flow velocity and ecological water level based on the model, and replenishing the river according to the ecological water replenishment amount; S30, Modular Construction of Physical Habitats: Constructing different physical habitat modules in the river; S40, Directed Reconstruction of Biological Habitats: Constructing different biological habitat communities in the river; S50, Habitat Monitoring and Regulation: Monitoring the river habitat status and regulating aquatic plant and animal populations based on the monitoring results, which can improve the ecological restoration effect of urban rivers and ensure the long-term stability of the river ecosystem.

Description

Technical Field

[0001] This application relates to the field of urban ecological engineering, and in particular to a method for restoring benthic animal habitats in urban waterways. Background Technology

[0002] Urban waterways not only provide urban residents with a comfortable living environment and recreational landscapes, forming a rare natural ecological environment for urban residents, but also provide human society with a variety of resources and services such as water supply, shipping, fisheries and landscapes, making them an important carrier for people's survival and development.

[0003] In recent years, with social development and progress, as well as the advancement of urbanization, human life has had an increasingly significant impact on urban river ecosystems. The discharge of domestic waste and various pollutants has led to river pollution and eutrophication, placing immense pressure on the ecological environment of urban rivers. Many urban rivers suffer from sediment pollution, habitat fragmentation, and altered hydrological characteristics. The combined effects of these multiple stresses have deprived most benthic animals of the necessary microenvironments and ecological niches, resulting in a significant decline in benthic species richness and endemic groups, loss of diversity, weakening the stability of urban river ecosystems, and even leading to the complete loss of natural river ecology and self-purification capacity. This severely restricts the improvement of urban living environments and the enhancement of residents' quality of life. Therefore, my country has put forward national requirements for the ecological protection and restoration of rivers, and ecological construction and modification projects for urban rivers have been successively and widely carried out in many parts of the country.

[0004] Existing urban river ecological restoration methods primarily focus on dredging and restoring aquatic life, neglecting the artificial establishment and maintenance of flora and fauna, resulting in slow ecological recovery. They also tend to emphasize ecological environment acceptance upon project completion, neglecting long-term monitoring and artificial maintenance, easily leading to the gradual degradation of river ecosystems after restoration. Furthermore, the lack of assessment and intervention standards for degraded river ecosystems makes it difficult to guarantee the long-term stability of restored urban river ecosystems. Summary of the Invention

[0005] To improve the ecological restoration effect of urban rivers and ensure the long-term stability of river ecosystems, this application provides a method for restoring benthic animal habitats in urban rivers.

[0006] The method for restoring benthic animal habitats in urban waterways provided in this application adopts the following technical solution: A method for restoring benthic animal habitats in urban rivers includes the following steps: S10, Basement Diagnosis and Targeted Restoration: Surveying the elevation, morphology, and structure of the riverbed, assessing the degree of sediment pollution, and carrying out targeted restoration of areas where the pollution level reaches a set standard; S20, Hydrological Simulation and Optimized Control: Constructing a river hydrodynamic model based on the riverbed survey results, simulating river flow velocity and water level under different replenishment volumes, determining the ecological flow velocity and ecological water level required to maintain the river habitat, obtaining the ecological replenishment volume based on the river hydrodynamic model, and then replenishing the river according to the ecological replenishment volume; S30, Modular Construction of Physical Habitats: Constructing different physical habitat modules in the river; S40, Directed Reconstruction of Biological Habitats: Constructing different biological habitat communities in the river; S50, Habitat Monitoring and Regulation: Monitoring the river habitat status and regulating aquatic plant and animal populations based on the monitoring results.

[0007] By adopting the above-mentioned technical solutions and using targeted remediation methods on areas where the sediment pollution level reaches a set standard, the amount of sediment remediation work can be reduced, thus lowering the cost of remediation projects while ensuring the effectiveness of river ecological restoration. Using hydrodynamic models to obtain the required ecological flow velocity and water level for maintaining river habitats enables precise water replenishment of urban rivers, reducing tensile stress at the connection between stress-bearing and anchoring edges and improving the stability of the stress-bearing frame structure. Monitoring the river habitat status allows for the timely detection of anomalies in urban river habitats, enabling intervention when abnormalities occur and ensuring long-term stability of the river habitat.

[0008] In one specific implementation scheme, in step S10, the degree of sediment pollution is assessed based on the total nitrogen, total phosphorus, and organic matter content in the sediment. When organic matter > 67.2 g / kg, total nitrogen > 1600 mg / kg, or total phosphorus > 1100 mg / kg, the targeted remediation of the riverbed is carried out.

[0009] By adopting the above technical solutions, the pollution level of sediment can be assessed based on the content of total nitrogen, total phosphorus and organic matter in the sediment according to the established assessment standards. Targeted remediation of riverbeds with excessive pollution levels can be carried out, which can reasonably reduce the amount of engineering work required for sediment remediation while ensuring the effectiveness of the remediation and effectively reduce the engineering cost of habitat restoration.

[0010] In one specific feasible implementation, the targeted remediation includes sediment elution and sediment improvement. The sediment is eluted at least three times, with a elution depth of at least 35 cm. After elution, the organic matter content in the sediment is ≤44.8 g / kg, total nitrogen ≤1100 mg / kg, and total phosphorus ≤730 mg / kg. Sediment improvement involves adding a sediment conditioner to the sediment. This conditioner comprises 30%–40% calcium oxide, 20%–30% zeolite powder, 30%–40% bio-granular fertilizer, and 0.05%–0.1% rare earth elements by mass. The dosage of the sediment conditioner is 80–100 g / m³. 2 The addition depth is 20-40cm below the surface of the washed sediment.

[0011] By employing the above-mentioned technical solutions and rinsing the bottom sediment at least three times to a depth of 35cm, the content of pollutants such as organic matter, total nitrogen, and total phosphorus in the sediment can be effectively reduced, thus lowering the degree of sediment pollution and contributing to the restoration of the urban river's ecological environment. Adding a sediment conditioner composed of a predetermined ratio of calcium oxide, zeolite powder, bio-granular fertilizer, and rare earth elements to the sediment utilizes the conditioner's unique adsorption and ion exchange properties to neutralize various organic acids in the sediment, creating an acidic environment and activating the activity of microorganisms and enzymes in the sediment, thereby promoting the recovery and growth of aquatic plants and animals.

[0012] In one specific implementation scheme, the method for improving the bottom sediment includes the following steps: S101, segmented drainage: draining water from the river in segments to expose the bottom sediment; S102, drying and tilling: drying and tilling the bottom sediment to a set depth to make it loose; S103, spreading bottom sediment improver: spreading bottom sediment improver on the tilled bottom sediment; S104, mixing and leveling: mixing the bottom sediment improver with the bottom sediment and then leveling the surface of the bottom sediment.

[0013] By adopting the above technical solution and utilizing segmented drainage of urban waterways, the riverbed can be improved in stages according to the degree of pollution in the sediment. Sun-drying the sediment and tilling it to a set depth facilitates thorough mixing of the sediment conditioner with the sediment, enhancing the improvement effect on the sediment's biological environment.

[0014] In a specific feasible implementation, in step S20, the method for determining the ecological flow velocity and ecological water level of the river is as follows: for the main stream of the river with a water surface width greater than 10m, the ecological flow velocity is 0.15-0.30m / s and the ecological water depth is 1.0-2.0m; for the tributary of the river with a water surface width less than 10m, the ecological flow velocity is 0.13-0.15m and the ecological water depth is 0.6-1.0m. Reclaimed water, external rivers, lakes and / or reservoirs are used as water sources to construct water replenishment pumping stations to replenish the river ecologically. The process parameters of the water replenishment pumping stations and water replenishment pipelines are calculated based on the water replenishment source, river water level and ecological water replenishment volume.

[0015] By adopting the above-mentioned technical solutions and controlling different ecological flow velocities and ecological water depths in sections of the river with varying water surface widths, it is possible to create ecological environments suitable for the growth of different species in different sections of the river, which is conducive to the formation of diverse ecological environments in the river. Furthermore, by utilizing water replenishment pumping stations and pipelines constructed according to the type of water source, river water level, and ecological water replenishment volume, the long-term ecological water replenishment requirements of urban rivers can be better met, facilitating the maintenance of the stability of the urban river ecological environment.

[0016] In a specific feasible implementation, in step S30, the physical habitat module includes a pebble group, an anti-erosion shoal, an anti-siltation pond, an emergent plant planting trough, and an ecological groyne. The pebble group is constructed in the upstream and narrowing sections of the river channel, forming an inverted "V" shape from upstream to downstream. The anti-erosion shoal is formed by filling and raising the soil near the water's edge below the river surface, and adding coarse sand, gravel, pebbles, or plain soil. Ecological bags are placed at the edge of the anti-erosion shoal, and retaining wooden stakes are placed on the water-facing side. The anti-siltation pond is formed by deepening the riverbed by dredging the river channel, and gabions are placed around the perimeter of the anti-siltation pond. The emergent plant planting trough is set near the bank in the river channel, formed by gabions and ecological bags surrounding the riverbank. The ecological groyne is formed by extending the gabions outside the emergent plant planting trough into the river channel, with an angle of 25-30° with the riverbank. Retaining wooden stakes are placed around the emergent plant planting trough and the ecological groyne.

[0017] By employing the above-mentioned technical solutions, pebble shoals can create diverse water depth, substrate, and flow velocity conditions in river channels, forming micro-habitats that provide shelter or breeding grounds for aquatic insects, fish, and benthic animals. Anti-scour shoals can create environments suitable for aquatic plant growth and provide habitats for benthic animals. Anti-siltation pools can create a relatively slow-flowing, relatively constant-temperature deep-water environment, providing overwintering sites for various oligochaetes and molluscs. Emergent plant planting troughs can create an ecological environment suitable for emergent plant growth, while ecological groynes can mitigate the scouring of benthic animals during periods of increased flow velocity in the flood season, improving water flow while protecting the emergent plant planting troughs and creating favorable habitat conditions for benthic animal growth.

[0018] In one specific implementation plan, multiple scour-resistant shoals are provided, with a total area of ​​1-3% of the riverbed area, a gravel thickness of 200-400mm, and a water depth of 0.2-0.3m; multiple anti-siltation pools are provided, with a total area of ​​3-5% of the riverbed area, and the area of ​​a single anti-siltation pool is 30-50m². 2 The depth is 0.5-1m below the riverbed, and the length of the ecological groynes is 10% of the width of the river channel, with a height of 1m.

[0019] By adopting the above technical solutions, and by controlling the area and water depth of the anti-scour shoals, as well as the area and depth of the anti-siltation pools, a diverse ecological environment in a set proportion can be formed in the river channel, which is suitable for the growth of a variety of aquatic organisms and is conducive to the formation of a diverse aquatic plant and animal population ecosystem in the river channel.

[0020] In one specific implementation scheme, in step S40, the biological habitat community includes emergent plant community, submerged plant community, and aquatic animal community. The emergent plant community is planted near the riverbank, on the erosion-resistant shallows, and in the emergent plant planting trough, with a planting density of 20-30 plants / m². 2 The submerged plant community is set up in sections of the river where the flow velocity is below 0.5 m / s. The planting area of ​​the submerged plant community is 20-30% of the riverbed area, with a planting density of 80-110 plants / m2. The aquatic animal community includes mussels, fish, and snails. The mussels include triangular sail mussels, pleated crown mussels, toothless mussels, and river clams, with a size of 4-8 cm and a stocking density of 4-5.5 kg / mu. The fish are bitterlings, with a size of 2-3 cm and a stocking density of 1.6-2.2 kg / mu. The snails include ringed snails and field snails, with a stocking density of 8-12 kg / mu. The stocking area is calculated as 5% of the riverbank area.

[0021] By adopting the above-mentioned technical solutions and planting a predetermined number and density of submerged and aquatic plant communities in the river channel, a suitable ecological environment for the growth and habitat of different aquatic animals can be formed, thus enhancing the guarantee for the restoration of the river's ecological environment. Introducing different species and quantities of aquatic animals into the river channel can create a diverse biological and animal ecological environment, supporting and regulating the growth of aquatic plants and ensuring the stability of the aquatic plant and animal ecological environment.

[0022] In one specific implementation scheme, in step S50, the detection of the river habitat environment includes automatic habitat monitoring, aquatic plant survey and assessment, and benthic animal survey and assessment. The automatic habitat monitoring is carried out by setting up automatic habitat monitoring instruments and underwater camera monitoring systems in the river. The aquatic plant survey and assessment and the benthic animal survey and assessment are carried out manually once a quarter. The Shannon-Wiener diversity index is used to evaluate the habitat status of aquatic plants, and the benthic animal status index is used to evaluate the habitat status of benthic animals.

[0023] By adopting the above-mentioned technical solutions and utilizing automatic habitat monitoring instruments and underwater camera monitoring systems installed in the river channel, pollutant indicators and aquatic animal growth in the water can be monitored in real time. This allows for timely artificial intervention when monitoring indicators exceed set ranges, ensuring the long-term stability of the river ecosystem. Regular surveys and assessments of the growth of aquatic plants and benthic animals enable standardized evaluation of their ecological status based on the survey results. Timely intervention is then implemented when the ecological status deviates from the ideal state, ensuring the stability of the river's aquatic plant and benthic animal habitats.

[0024] In a specific feasible implementation, in step S50, the methods for regulating aquatic plant and animal populations include water level regulation, fish population regulation, submerged plant population regulation, and benthic animal regulation. The water level regulation method involves lowering the normal water level of the river channel by 0.3-0.5m in spring and raising it by 0.5-0.7m in summer. The fish population regulation method involves introducing filter-feeding fish, carnivorous fish, and detritivorous / omnivorous fish into the river channel at a ratio of 1:2:1, at a rate of 4-6 kg / mu. The submerged plant population regulation method involves regularly pruning submerged plants according to the season. The benthic animal regulation method involves replenishing benthic animals by 30-40% of the initial amount when the amount or density of benthic animals in the river channel decreases by more than 30% compared to the initial amount, and harvesting 50-70% of the existing benthic animal population when the amount or density of benthic animals increases by more than 100% compared to the initial amount.

[0025] By adopting the above-mentioned technical solutions, and by using methods such as regulating water levels, releasing or catching fish, pruning submerged plants, and controlling benthic animals, it is possible to conveniently regulate the status of aquatic plant and animal populations, maintain the diversity of river ecological status, ensure the health and stability of urban river aquatic ecosystems, and achieve long-term sustainability of ecological restoration.

[0026] In summary, this application includes at least one of the following beneficial technical effects: By diagnosing and targeting the riverbed, targeted remediation can be carried out on parts of urban rivers where pollution levels exceed set standards. By combining two remediation technologies—sediment washing and sediment improvement—simultaneous improvement of the riverbed's physical structure and chemical environment can be achieved. Compared to traditional overall river dredging and environmental modification, the remediation is more targeted, and the modified riverbed is more conducive to the growth of aquatic plants and animals, resulting in better ecological restoration. By establishing different physical habitats such as pebble groups, scour-prevention shoals, silt-prevention pools, emergent plant planting troughs, and ecological groynes in the river channel, as well as reconstructing biological habitats such as emergent plant communities, submerged plant communities, and aquatic animal communities, and by optimizing the hydrological conditions of the river channel, it is possible to establish a diverse living and growing environment for aquatic organisms in the river channel, which is conducive to maintaining the diversity and stability of urban river ecosystems. Real-time monitoring of pollutants in river water and regular surveys and evaluations of aquatic plant and animal population diversity can promptly identify imbalances in the status of aquatic plant and animal populations in the river and allow for timely artificial regulation, which is conducive to maintaining the long-term health and stability of urban river ecosystems. By using a sediment conditioner composed of calcium oxide, zeolite powder, bio-granular fertilizer, and rare earth elements, and by rationally setting the ratio of different components, the sediment conditioner can form unique adsorption and ion exchange properties. It can neutralize various organic acids in the sediment, change the acidic environment of the riverbed, activate the activity of sediment microorganisms and enzymes, and promote the growth and recovery of aquatic plants and animals. Attached Figure Description

[0027] Figure 1 This is a flowchart of one embodiment of the present application.

[0028] Figure 2 This is a flowchart of a sediment improvement method in one embodiment of this application.

[0029] Figure 3 This is a schematic diagram of a habitat in an urban river channel according to one embodiment of this application.

[0030] Figure 4 This is a schematic diagram of an anti-scouring shoal structure in one embodiment of this application.

[0031] Figure 5 This is a schematic diagram of an emergent plant planting trough and an ecological groyne in one embodiment of this application.

[0032] Explanation of the attached diagram labels: 1. Riverbed; 2. Pebble beach; 3. Anti-erosion shoal; 4. Anti-siltation pool; 5. Emergent plant planting trough; 6. Ecological groynes; 7. Barrier piles; 8. Gabions; 9. Ecological bags; 10. Backfill soil; 11. Coarse sand; 12. Emergent plants; 13. Submerged plants; 14. Riverbank; 15. Water surface. Detailed Implementation

[0033] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] An embodiment of the method for restoring benthic animal habitats in urban waterways in this application, such as Figure 1 As shown, it includes the following steps: S10, Basal Diagnosis and Targeted Repair.

[0036] A systematic survey of the elevation, morphology, and structure of the urban riverbed is conducted, and a riverbed cross-section map at a scale of no less than 1:100 is drawn. The proportion of different geological states such as clay, silt, sand, gravel, and pebbles in the surface layer of the riverbed is investigated. The chemical properties such as total nitrogen, total phosphorus, organic matter content, and heavy metals are analyzed. The degree of sediment pollution is assessed based on sediment nutrient monitoring indicators. Targeted remediation is carried out on the riverbed that meets the remediation standards, so that the riverbed is suitable for the growth of aquatic plants and forms a suitable substrate environment for the habitat and growth of aquatic animals.

[0037] S20, hydrological simulation and optimization control.

[0038] Based on the results of the riverbed survey, an InfoWorks ICM software was used to construct a river hydrodynamic model to simulate the river flow velocity and water level in different sections under different water replenishment volumes, so as to understand the distribution of flow velocity and water level in different sections of the river under different water replenishment volumes.

[0039] By combining the river's geographical location, riverbed structure, and local flora and fauna, the ecological flow velocity and ecological water level required to maintain river biodiversity are determined. The corresponding ecological water replenishment volume is then obtained using the InfoWorks ICM river hydrodynamic model. Water replenishment facilities are constructed to supply water to the urban river according to the ecological replenishment volume, creating a hydrological environment within the river that can maintain biodiversity.

[0040] S30, Modular construction of physical habitat.

[0041] Physical habitat modules suitable for the growth and habitation of different aquatic organisms are constructed in the river channel, such as pebbles, shallows, and deep pools, to form an underwater physical environment suitable for the growth and habitation of different aquatic plants and animals.

[0042] S40, Targeted reconstruction of biological habitats.

[0043] Planting suitable aquatic plants in different areas of the river channel creates a diverse aquatic plant community. Introducing appropriate aquatic animal species and controlling the quantity of different species establishes diverse biological habitats within the river. This creates rich ecological microenvironments at varying water depths, providing natural environments conducive to the resting, recuperating, hiding, and attaching of organisms. It also provides spawning and reproduction sites for large benthic animals and other aquatic organisms, establishing a rational benthic food chain and ensuring a healthy ecological balance within the river.

[0044] S50, Habitat monitoring and regulation.

[0045] Utilize appropriate methods to monitor the ecological environment of river channels, including hydrological indicators such as flow velocity and discharge, and water quality indicators such as pH, ORP, temperature, dissolved oxygen, conductivity, COD, ammonia nitrogen, and total phosphorus; monitor the growth of fish and benthic animals in the river, and the growth of various aquatic plants. Based on the monitoring results, evaluate the diversity and stability of the river ecosystem, and promptly intervene artificially when the ecosystem becomes unbalanced or degraded to correct imbalanced plant and animal populations, ensuring the long-term health and stability of urban river ecosystems.

[0046] In some embodiments of the urban river benthic animal habitat restoration method of this application, during the substrate diagnosis process in step S10, sediment from different sections of the river is extracted for analysis of total nitrogen, total phosphorus, and organic matter content, and the degree of sediment pollution is determined based on the total nitrogen, total phosphorus, and organic matter content in the sediment. Specifically, when any one of the following is met: organic matter > 67.2 g / kg, total nitrogen > 1600 mg / kg, and total phosphorus > 1100 mg / kg, the nutrient index of the sediment is considered to have reached a moderate pollution level, requiring targeted remediation of the riverbed in that section to reduce the nutrient content in the sediment, decrease the pollution factors in the sediment, and improve the cleanliness of the sediment.

[0047] In a preferred embodiment of the urban river benthic habitat restoration method of this application, the targeted restoration method for the riverbed includes sediment elution and sediment improvement. Sediment elution refers to a sediment pollution treatment technology that uses physical disturbance to generate turbulence at the mud-water interface, causing colloidal sediments in the sediment to tumble, collide, and rub against each other. Inorganic particles settle due to gravity and are covered in situ. Smaller colloidal pollutants are pumped out with the water, undergo flocculation and sedimentation, and are then filtered and transported off-site. The flocculated and separated clean water is then returned to the river. After sediment elution, larger inorganic sediment particles cover the riverbed, thereby forming a stable mud-water interface, improving the aquatic habitat, and promoting the growth and recovery of benthic animals.

[0048] The specific steps of sediment washing are as follows: sediment disturbance, sludge-water lifting, wastewater separation, clean water return to the river, sludge dewatering, and sludge transportation. Sediment disturbance involves using mechanical devices to agitate the sediment, causing particulate matter to mix with water. Sludge-water lifting involves using a pump to extract the colloid formed by the sediment-water mixture from the river channel and transport it to the riverbank for further treatment. Wastewater separation involves using static separation or filtration devices to separate colloidal pollutants from the sludge-water mixture, forming sludge and clean water. Clean water return to the river involves using pipes or pumps to return the separated clean water with lower pollutant content back to the river channel. Sludge dewatering involves using centrifuges to further remove water from the sludge, reducing the amount of sludge requiring treatment and minimizing pollution during sludge transportation and landfill disposal. Sludge transportation involves transporting the dewatered wastewater to suitable locations for treatment, including landfill disposal and post-contamination reuse.

[0049] For sediments that have reached a moderate level of pollution, the elution process should be repeated at least three times, with a elution depth of at least 35 cm. After elution, the nutrient content of the sediment should be analyzed again. If the organic matter content is ≤44.8 g / kg, total nitrogen is ≤1100 mg / kg, and total phosphorus is ≤730 mg / kg, the sediment is considered to have reached a clean nutrient level, and elution should be stopped; otherwise, one more elution process should be performed.

[0050] If, during the baseline diagnostic process, the organic matter content in the sediment is detected to be >89.6 g / kg, total nitrogen >2000 mg / kg, or total phosphorus >1500 mg / kg, the sediment is considered to be heavily contaminated. The sediment should be eluted at least four times, with a elution depth of at least 40 cm. After elution, the nutrient content of the sediment should be analyzed again. If the nutrient content of the sediment reaches a clean level after elution, elution should be stopped; otherwise, one more elution cycle should be performed.

[0051] The method for improving sediment bottom involves adding a sediment conditioner to the sediment. This conditioner is a mixture of calcium oxide, zeolite powder, bio-granular fertilizer, and rare earth elements. Calcium oxide neutralizes humic acid in the sediment, adjusting its pH. Zeolite powder adsorbs ammonia nitrogen from interstitial water and overlying water, inhibiting its release into the water body and reducing total nitrogen pollution. It also adsorbs organic matter, reducing the oxygen consumption of organic matter decomposition, thus improving the redox state and microbial environment of the sediment. Furthermore, it fixes heavy metals in the sediment through ion exchange, reducing the risk of heavy metal accumulation through aquatic plants and benthic animals. The bio-granular fertilizer contains various beneficial bacteria such as Bacillus subtilis and Bacillus licheniformis, directly supplementing nutrients for aquatic plant growth. It also utilizes beneficial microorganisms such as Bacillus subtilis, Bacillus licheniformis, photosynthetic bacteria, and lactic acid bacteria to convert fixed nutrients in the sediment into available forms, continuously supplying aquatic plants and improving nutrient utilization. Rare earth is an agricultural rare earth complex containing all 17 rare earth elements. It can activate the number of nitrifying bacteria and free-living nitrogen-fixing bacteria in the soil, promote nitrogen conversion, optimize the soil micro-ecological balance, and regulate soil fertility. The components work synergistically to construct "adsorption-biodegradation" micro-units and continuously replenish microorganisms, forming a self-repairing bottom sediment environment and creating excellent substrate conditions for the growth of aquatic plants and animals.

[0052] Specifically, the sediment conditioner contains 30-40 wt% calcium oxide, 20-30 wt% zeolite powder, 30-40 wt% bio-granular fertilizer, and 0.05-0.1 wt% rare earth elements. The dosage is 80-100 g / m² based on the riverbed area of ​​the remediation section. 2 The addition depth is 20-40cm below the surface of the washed sediment.

[0053] As a specific implementation method of the urban river benthic animal habitat restoration method of this application, such as Figure 2 As shown, the specific steps for improving the substrate are as follows: S101, Segmented drainage.

[0054] Dams were constructed upstream and downstream of the sections of the river channel that required foundation restoration, and water was discharged from those sections in stages to expose the bottom sediment.

[0055] S102, Drying and plowing.

[0056] The bottom sediment of the riverbed is dried to reduce its water content and viscosity. Once the viscosity of the sediment has decreased to a certain level, it is tilled to a depth no less than the predetermined depth for adding the sediment conditioner. This loosens the sediment, allowing the conditioner to penetrate deeper and mix with the sediment.

[0057] S103, Spread substrate conditioner.

[0058] A soil conditioner is spread on the tilled bottom mud to ensure that it is evenly distributed. Some of the conditioner enters the bottom mud through the gaps in the tilled mud.

[0059] S104, Mix and level.

[0060] Using a harrowing machine, the soil on which the soil conditioner has been spread is harrowed to ensure that the soil conditioner is fully mixed with the soil. The soil that has been turned over is broken up and leveled to form a smooth soil surface.

[0061] In some embodiments of the urban river benthic animal habitat restoration method of this application, in step S20, the ecological flow velocity and ecological water level of the river are determined as follows: for the main stream of the river with a water surface width greater than 10m, the ecological flow velocity is determined to be 0.15-0.30m / s in the main channel; the ecological water depth is determined to be 1.0-2.0m in the main body of the river. For tributaries of the river with a water surface width less than 10m, the ecological flow velocity is determined to be 0.13-0.15m in the main channel, and the ecological water depth is determined to be 0.6-1.0m in the river.

[0062] Based on the local water resources situation, reclaimed water, external rivers, lakes, and / or reservoirs are selected as water replenishment sources. Water replenishment pumping stations are constructed at the water replenishment sources, and water replenishment pipelines are built between the pumping stations and urban waterways. Water from the replenishment sources is transported to the urban waterways according to the ecological replenishment volume, thus providing ecological water replenishment. The process parameters for the water replenishment pumping stations and pipelines are calculated based on the nature and location of the water replenishment sources, the river water level, and the amount of ecological replenishment. The design and construction of the water replenishment pumping stations and pipelines are carried out according to these process parameters.

[0063] In some embodiments of the urban river benthic animal habitat restoration method of this application, in step S30, the physical habitat modules constructed in the river include pebble beds, erosion-resistant shoals, anti-siltation pools, emergent plant planting troughs, and ecological groynes. For example... Figure 3 As shown, pebble groups 2 are set up in the upper reaches and narrow sections of the river channel. Pebble groups 2 help to create water depth, substrate and flow velocity conditions with diverse characteristics. The micro-habitats created can provide shelter or breeding grounds for aquatic insects, fish and benthic animals.

[0064] Figure 3The arrows indicate the direction of water flow in the river channel. Pebble Group 2 is formed by arranging multiple pebbles, each with a diameter of 500-1000mm, in an inverted "V" shape from upstream to downstream. When the river flows through Pebble Group 2, it creates three distinct zones behind it: a still water zone with a flow velocity of 0.01-0.03m / s, a slow-flowing zone with a flow velocity of 0.10-0.15m / s, and a fast-flowing zone with a flow velocity of 0.15-0.30m / s. This creates a diverse aquatic environment and enhances the riverbed's reoxygenation capacity.

[0065] In the near-water edge area below the river surface, fill and raise the area, adding coarse sand, gravel, pebbles, or plain soil to construct a shoal, forming an anti-erosion shallow beach. (Example:) Figure 4 As shown, an anti-erosion shoal 3 is constructed along the riverbank 14. Backfill soil 10 is piled on the riverbed 1, and ecological bags 9 are used for slope protection on the outer side of the backfill soil 10 and the edge of the anti-erosion shoal 3. A row of retaining wooden piles 7 is set on the water-facing side of the anti-erosion shoal 3. The retaining wooden piles 7 and ecological bags 9 are used to block the water flow in the river channel, forming an anti-erosion shoal 3. The anti-erosion shoal 3 can meet the growth needs of aquatic plants and provide a high-quality habitat for benthic animals using plant roots and stems.

[0066] The anti-siltation pond 4 is formed by dredging the riverbed in sections. A ring of gabions 8 filled with boulders is placed on the riverbed 1 outside the boundary of the anti-siltation pond 4 to prevent silt from accumulating in the pond. The anti-siltation pond 4 can create a deep-water environment with relatively slow water flow and relatively constant water temperature, providing a wintering place for various oligochaetes and soft-bodied benthic animals.

[0067] Planting troughs 5 for emergent plants are set up near the bank in the river channel, such as... Figure 5 As shown, the emergent plant planting trough 5 is usually constructed along the riverbank 14 and is formed by gabions 8 and eco-bags 9 surrounding the riverbank 14. Dividing wooden stakes are set on the water-facing side of the gabions 8 and eco-bags 9, and soil 10 is backfilled in the emergent plant planting trough 5 for planting emergent plants 12.

[0068] The ecological groyne 6 is formed by extending gabions 8 from the outer side of the emergent plant planting trough 5 into the river channel. The ecological groyne 6 is typically located in a straight section of the river channel, constructed using gabions to form a meandering groyne at a 25-30° angle to the riverbank 14. This serves to mitigate the scouring of benthic animals by increased flow velocity during the flood season. The interior of the ecological groyne 6 is filled with 20-50mm gravel, and a row of retaining wooden stakes 7 reinforces the outer side. The ecological groyne 6 connects to the sidewalls of the emergent plant planting trough 5, improving water flow while protecting the trough from scouring, thus creating favorable habitat conditions for benthic animal recovery.

[0069] In a preferred embodiment of the urban river benthic animal habitat restoration method of this application, multiple scour-resistant shoals 3 are set up in the river channel, with a total area of ​​1% to 3% of the riverbed area. For example... Figure 4 As shown, a layer of coarse sand 11 or gravel, 200-300 mm thick, typically 250 mm thick, is placed over the backfill soil 10 at the edge of the erosion-resistant shoal 3, so that the surface layer of coarse sand 11 or gravel is 0.2-0.3 m below the water surface 15. The coarse sand 11 or gravel substrate of the shoal can provide a better habitat for benthic animals.

[0070] like Figure 1 As shown, multiple anti-siltation ponds 4 are typically set up in the river channel. The total area of ​​the anti-siltation ponds 4 is 3-5% of the riverbed area, and the area of ​​a single anti-siltation pond 4 is set at 30-50m². 2 When setting up the anti-siltation pond 4, it is usually excavated to a depth of 0.5-1.0 meters on the riverbed 1 to ensure the stability of the bottom water temperature of the anti-siltation pond 4 and to provide a sufficient area and good winter survival environment for benthic animals.

[0071] The ecological groynes are 10% the width of the river channel and 1m high. They are used to block the water flow in straight river sections and create areas with different flow velocities in the river channel.

[0072] In another preferred embodiment of the urban river benthic animal habitat restoration method of this application, in step S40, the constructed biological habitat community includes emergent plant communities, submerged plant communities, and aquatic animal communities. For example... Figure 1 As shown, the emergent plant community is formed by various emergent plants 12 planted near the riverbank 14. A composite shallow water habitat formed by gabions 8 coupled with eco-bags 9 can be constructed along the riverbank 14, and emergent plants 12 can be planted in this composite shallow water habitat. Emergent plants 12 can also be planted on the anti-erosion shoals 3 and in emergent plant planting troughs 5.

[0073] The 12 emergent plants planted include yellow iris, aquatic canna, and thaliana, which slow down water flow, with a planting density of 20-30 plants / m². 2 In this embodiment, the planting density is 25 plants / m². 2 Emergent plants can form a transitional zone between aquatic and terrestrial habitats in the near-shore area of ​​river channels, which can help to impede water flow and reduce erosion, and provide a living environment and refuge for benthic animals with attached roots and rhizomes.

[0074] Submerged plant communities are established in sections of the river where the flow velocity is below 0.5 m / s, formed by planting submerged plants 13 on the riverbed. The submerged plants 13 typically planted include *Potamogeton crispus*, *Vallisneria natans*, and *Myriophyllum spicatum*. In sections with faster flow velocities, these plants with strong anchorage abilities are planted; in sections with slower flow velocities, plants with weaker root anchorage abilities, such as *Hydrilla verticillata*, *Ceratophyllum demersum*, and *Potamogeton crispus*, are planted. The planting area of ​​the submerged plant community is 20-30% of the riverbed area, with a planting density of 80-110 plants / m². 2 ; Aquatic animals such as mussels, fish, and snails are released into the river. The mussels include triangular sail mussels, pleated crown mussels, toothless mussels, and river clams, with a size of 4-8cm and a release rate of 4-5.5kg / mu. The fish released are bitterlings, with a size of 2-3cm and a release density of 1.6-2.2kg / mu. The snails released include ringed snails and field snails, with a release density of 8-12kg / mu. The release area is calculated as 5% of the riverbank area.

[0075] Aquatic animals released into rivers will find suitable habitats and form aquatic animal community together with native aquatic animals. Large benthic animals such as snails and clams, as well as symbiotic host fish such as bitterlings, can promote the extension and restoration of the benthic animal food chain.

[0076] In some embodiments of the urban river benthic animal habitat restoration method of this application, step S50, detecting the river habitat environment includes automatic habitat monitoring, aquatic plant survey and assessment, and benthic animal survey and assessment. Automatic habitat monitoring is conducted by installing automatic habitat monitoring instruments and underwater camera monitoring systems in the river. These instruments are deployed in the upper, middle, and lower reaches of the river and at key nodes. The habitat monitoring instruments monitor hydrological indicators such as flow velocity and flow rate, as well as water quality indicators such as pH, ORP, temperature, dissolved oxygen, conductivity, COD, ammonia nitrogen, and total phosphorus in real time. The underwater camera monitoring system observes the growth of fish and benthic animals in real time. The monitoring results can also be wirelessly transmitted to a smart monitoring platform, which displays river habitat data and analysis results comprehensively, multidimensionally, and in multiple formats, enabling intelligent water ecological management.

[0077] Aquatic plant surveys and assessments are conducted once per season. The survey content includes: the species composition and distribution characteristics of aquatic plants, as well as the coverage and biomass of aquatic plants. The Shannon-Wiener diversity index is used as the evaluation index to assess the habitat status of aquatic plants in the river.

[0078] A benthic animal survey and assessment is conducted every season. The survey includes the species composition, density and biomass of benthic animals, dominant species, etc. The Benthic Animal Status Index (BQI) is used as the evaluation index to assess the habitat status of benthic animals.

[0079] In a preferred embodiment of the urban river benthic animal habitat restoration method of this application, the method for regulating aquatic animal and plant populations in step S50 includes water level regulation, fish population regulation, and submerged plant population regulation. Through regulation, the imbalanced animal and plant ecology in urban rivers is artificially corrected, and the balance and stability of the ecological environment in the river is maintained.

[0080] The water level regulation method is to lower the normal water level of the river channel by 0.3-0.5m in spring so that more sunlight can reach the riverbed and promote the germination of submerged plants; and to raise the normal water level of the river channel by 0.5-0.7m in summer to inhibit the excessive growth of submerged plants.

[0081] The method for fish population control is as follows: when the submerged plant cover in the river channel is monitored to be greater than 70%, fish are introduced into the river channel at a rate of 4-6 kg / mu, usually 5 kg / mu. The introduced fish include filter feeders, carnivorous fish, and detritivorous / omnivorous fish, with a ratio of filter feeders / carnivorous fish to detritivorous / omnivorous fish of 1:2:1, and a size of 100-300g / fish. This fish introduction maintains the submerged plant cover at 40-70% and ensures that the Shannon-Wiener diversity index of aquatic organisms is greater than 2.0.

[0082] The method for controlling the population of submerged plants is to regularly prune them. The pruning frequency is once a month in spring and autumn, and once every half month in summer, to ensure that the coverage of submerged plants is between 40% and 70% after pruning.

[0083] Benthic animal populations are regulated through restocking and harvesting. When monitoring shows that the density or biomass of benthic animals has decreased by more than 30% compared to the initial stocking, restocking should be carried out at 30%–40% of the original stocking density. When the density or biomass of benthic animals increases by more than 100% of the initial stocking, benthic animals should be harvested, with the harvesting amount being 50%–70% of their total biomass. The benthic animal condition index (BQI) should be maintained at no less than 70 through restocking or harvesting.

[0084] By regulating aquatic plant and animal populations as described above, the integrity and stability of the food chain structure in the river can be ensured, thereby maintaining the health and stability of the urban river aquatic ecosystem in the long term and achieving sustainable ecological restoration.

[0085] In the description of this invention, the terms "one embodiment," "specific embodiment," "preferred embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this invention, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0086] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for restoring benthic animal habitats in urban waterways, characterized in that, Includes the following steps: S10. Basement Diagnosis and Targeted Remediation: Survey the elevation, morphology and structure of the riverbed basement, assess the degree of sediment pollution, and carry out targeted remediation of areas where the pollution level reaches the set standard. S20. Hydrological simulation and optimization control: Based on the results of the riverbed survey, a river hydrodynamic model is constructed to simulate the river flow velocity and water level under different water replenishment volumes. The ecological flow velocity and ecological water level required to maintain the river habitat are determined. The ecological water replenishment volume is obtained based on the river hydrodynamic model, and then water is replenished to the river according to the ecological water replenishment volume. S30, Modular Construction of Physical Habitats: Constructing different physical habitat modules in the river channel; S40. Directed reconstruction of biological habitats: Constructing different biological habitat communities in the river channel; S50. Habitat monitoring and regulation: Monitor the state of river habitats and regulate aquatic plant and animal populations based on the monitoring results.

2. The method for restoring benthic animal habitats in urban waterways according to claim 1, characterized in that, In step S10, the degree of sediment pollution is assessed based on the total nitrogen, total phosphorus, and organic matter content in the sediment. When organic matter > 67.2 g / kg, total nitrogen > 1600 mg / kg, or total phosphorus > 1100 mg / kg, the targeted remediation of the riverbed is carried out.

3. The method for restoring benthic animal habitats in urban waterways according to claim 2, characterized in that, The targeted remediation includes sediment elution and sediment improvement. The sediment is eluted no less than 3 times, the elution depth is no less than 35cm, and the organic matter in the eluted sediment is ≤44.8g / kg, total nitrogen is ≤1100mg / kg, and total phosphorus is ≤730mg / kg. The bottom sediment improvement involves adding a bottom sediment conditioner to the sediment. This conditioner comprises 30%–40% calcium oxide, 20%–30% zeolite powder, 30%–40% bio-granular fertilizer, and 0.05%–0.1% rare earth elements by mass. The dosage of the bottom sediment conditioner is 80–100 g / m³. 2 The addition depth is 20-40cm below the surface of the washed sediment.

4. The method for restoring benthic animal habitats in urban waterways according to claim 3, characterized in that, The method for improving the substrate includes the following steps: S101, Segmented drainage: Water in the river is drained in segments to expose the bottom sediment; S102, Drying and Tilling: Drying and tilling the bottom mud to a set depth to make the bottom mud loose; S103, Spreading bottom soil conditioner: Spreading bottom soil conditioner on the bottom soil after tilling; S104. Mixing and leveling: After mixing the bottom conditioner with the bottom mud, level the surface of the bottom mud.

5. The method for restoring benthic animal habitats in urban waterways according to claim 1, characterized in that, In step S20, the ecological flow velocity and ecological water level of the river are determined as follows: for the main stream of the river with a water surface width greater than 10m, the ecological flow velocity is 0.15-0.30m / s and the ecological water depth is 1.0-2.0m; for the tributary of the river with a water surface width less than 10m, the ecological flow velocity is 0.13-0.15m / s and the ecological water depth is 0.6-1.0m. Reclaimed water, external rivers, lakes and / or reservoirs are used as water sources to construct water replenishment pumping stations to replenish the river for ecological purposes. The process parameters of the water replenishment pumping stations and water replenishment pipelines are calculated based on the water replenishment source, river water level and ecological water replenishment volume.

6. The method for restoring benthic animal habitats in urban waterways according to claim 1, characterized in that, In step S30, the physical habitat module includes a pebble group, an anti-erosion shoal, an anti-siltation pool, an emergent plant planting trough, and an ecological groyne. The pebble group is constructed in the upstream and narrowing sections of the river channel, forming an inverted "V" shape from upstream to downstream. The anti-erosion shoal is formed by filling and raising the soil near the water's edge below the river surface, and adding coarse sand, gravel, pebbles, or plain soil. Ecological bags are placed at the edges of the anti-erosion shoal, and retaining wooden stakes are placed on the water-facing side. The anti-siltation pool is formed by deepening the riverbed by dredging the river channel, and gabions are placed around the anti-siltation pool. The emergent plant planting trough is set near the bank in the river channel, formed by gabions and ecological bags surrounding the riverbank. The ecological groyne is formed by extending the gabions outside the emergent plant planting trough into the river channel, with an angle of 25-30° with the riverbank. Retaining wooden stakes are placed around the emergent plant planting trough and the ecological groyne.

7. The method for restoring benthic animal habitats in urban waterways according to claim 6, characterized in that, Multiple scour-prevention shoals are provided, with a total area of ​​1-3% of the riverbed area, a gravel thickness of 200-400mm, and a water depth of 0.2-0.3m. Multiple anti-siltation pools are provided, with a total area of ​​3-5% of the riverbed area, and each anti-siltation pool has an area of ​​30-50m². 2 The depth is 0.5-1m below the riverbed, and the length of the ecological groynes is 10% of the width of the river channel, with a height of 1m.

8. The method for restoring benthic animal habitats in urban waterways according to claim 6, characterized in that, In step S40, the biological habitat community includes emergent plant communities, submerged plant communities, and aquatic animal communities. The emergent plant communities are planted near the riverbank, on the erosion-resistant shallows, and in the emergent plant planting troughs, with a planting density of 20-30 plants / m². 2 The submerged plant community is planted in sections of the river where the flow velocity is below 0.5 m / s. The planting area of ​​the submerged plant community is 20-30% of the riverbed area, with a planting density of 80-110 plants / m². 2 The aquatic animal community includes mussels, fish, and snails. The mussels include triangular sail mussels, pleated crown mussels, toothless mussels, and river clams, with a size of 4-8cm and a stocking density of 4-5.5kg / mu. The fish are bitterlings, with a size of 2-3cm and a stocking density of 1.6-2.2kg / mu. The snails include ringed snails and field snails, with a stocking density of 8-12kg / mu. The stocking area is calculated as 5% of the riverbank area.

9. The method for restoring benthic animal habitats in urban waterways according to claim 1, characterized in that, In step S50, the detection of the river habitat environment includes automatic habitat monitoring, aquatic plant survey and assessment, and benthic animal survey and assessment. The automatic habitat monitoring is carried out by setting up automatic habitat monitoring instruments and underwater camera monitoring systems in the river. The aquatic plant survey and assessment and the benthic animal survey and assessment are carried out manually once a quarter. The Shannon-Wiener diversity index is used to evaluate the habitat status of aquatic plants, and the benthic animal status index is used to evaluate the habitat status of benthic animals.

10. The method for restoring benthic animal habitats in urban waterways according to claim 9, characterized in that, In step S50, the methods for regulating aquatic plant and animal populations include water level regulation, fish population regulation, submerged plant population regulation, and benthic animal regulation. The water level regulation method involves lowering the normal water level of the river channel by 0.3-0.5m in spring and raising it by 0.5-0.7m in summer. The fish population regulation method involves introducing filter-feeding fish, carnivorous fish, and detritivorous / omnivorous fish into the river channel at a ratio of 1:2:1, with a release rate of 4-6 kg / mu. The submerged plant population regulation method involves regularly pruning submerged plants according to the season. The benthic animal regulation method involves replenishing benthic animals by 30-40% of the initial amount when the amount or density of benthic animals in the river channel decreases by more than 30% compared to the initial amount, and harvesting 50-70% of the existing benthic animal population when the amount or density of benthic animals increases by more than 100% compared to the initial amount.

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