Light compensation and resuspension double-constrained water level pulse closed-loop submersed community restoration method

Abstract

This invention relates to the field of water treatment and aquatic ecosystem restoration technology, and particularly to a closed-loop method for restoring submerged communities using a water level pulse with dual constraints of light compensation and resuspension. The method calculates the light compensation depth based on aquatic environmental parameters and determines the target water level zone. It sequentially executes a low-water-level planting window setting, sediment endogenous source control procedures, and a gradual rise acclimatization stage, dynamically updating aquatic environmental parameters to correct the target water level zone. When water quality purification characterization parameters deviate from the purification control target threshold set and / or algal risk increases, a water level pulse is superimposed on the baseline operating water level to form a water level curve, and boundary constraints and protection are implemented using a weighted index of resuspension and endogenous release risks. The pulse parameters are adjusted according to a rolling cycle, and the water level is switched to maintain the purification maintenance stage to achieve full-cycle operation control. The method proposed in this invention can stably improve transparency, suppress algal blooms, and promote the restoration of submerged communities under high disturbance and high endogenous source conditions.

Description

Technical Field

[0001] This invention relates to the field of water treatment and aquatic ecological restoration technology, and in particular to a closed-loop water level pulse restoration method for submerged communities under dual constraints of light compensation and resuspension. By synergistically regulating water level operation through endogenous pollution control and light compensation constraints, the method achieves the restoration of submerged plant communities and the improvement of water quality, and belongs to the process control technology of water purification and in-situ ecological restoration. Background Technology

[0002] Eutrophication and its induced cyanobacterial blooms are typical water environment problems faced by shallow lakes, reservoirs, and landscape water bodies. Eutrophication is often accompanied by decreased water transparency, increased suspended particulate matter, intensified diurnal fluctuations in dissolved oxygen, and degradation of ecosystem structure. This is most prominently manifested in the decline or even disappearance of submerged plants, transforming the water body from a "grass-based clear water state" to an "algae-based turbid water state," leading to a decrease in the water body's self-purification capacity and a weakening of its landscape and ecosystem service functions. In ecological restoration and water purification projects, submerged plants play a crucial role in restoring clear water and improving water quality by constructing underwater habitats, absorbing and fixing nitrogen and phosphorus, inhibiting algae, and stabilizing bottom sediments.

[0003] However, in actual engineering projects, the phenomenon of "planting submerged plants - recovery failure - repeated replanting" is quite common. The main reasons are concentrated in three key bottlenecks: First, algal blooms and suspended particulate matter lead to insufficient underwater light, making it difficult for submerged plants to overcome the light compensation threshold in the early stages of establishment; Second, wind and wave disturbances or engineering disturbances in shallow water bodies cause sediment resuspension, which increases the abundance of particulate matter in the water column and further weakens the underwater light environment, forming a positive feedback loop of "turbidity - shading - decline"; Third, even if the external load is reduced, the phosphorus accumulated in the bottom sediment can still maintain a high phosphorus level in the water body through endogenous release, resulting in water quality improvement not meeting expectations. Moreover, the endogenous release process can last for a long time, thereby weakening the long-term stability of submerged plant recovery.

[0004] To address the aforementioned issues, existing engineering and patented technologies mainly include physical measures such as sediment dredging, water flushing, and aeration; chemical measures such as adding flocculation / algae removal / phosphorus fixation materials; and biological-ecological purification measures centered on aquatic plants. Among these, water level / depth control is widely used in aquatic ecological restoration projects because it directly affects underwater light, temperature, and hydrodynamic conditions. For example, Chinese invention patent CN106045053A proposes a method for water purification and submerged vegetation restoration in eutrophic water bodies with controllable water levels. This method involves lowering the water level to below 10 cm and sowing Vallisneria natans. After approximately 15 days, the water level is adjusted to 25–40 cm, and other pioneer submerged plants are propagated. Subsequently, the water level is raised to 1–1.2 m and then further raised to above 1.5 m to achieve plant colony establishment and purification. This scheme embodies the idea of ​​"phased water level gradient + species configuration," but its water level regulation relies more on preset steps and lacks quantitative constraints based on transparency / light attenuation and light compensation depth. Furthermore, it lacks an online constraint mechanism for the operational risks of "wind and waves—resuspension—turbidity surge," and the control of endogenous release from sediment usually depends on external management or general measures, making it difficult to achieve replicable and stable purification effects in shallow water systems with strong disturbances and high endogenous loads. For example, Chinese invention publication CN104743675A discloses a method for controlling the growth of submerged plants to treat lake eutrophication by regulating water depth, emphasizing planting and regulating water depth at key time points to provide submerged plants with optimal light and water temperature conditions. While these methods have certain advantages in terms of engineering operability, they are generally based on "empirical periods / critical nodes" and are difficult to adapt to situations with rapid fluctuations in water transparency, frequent resuspension events, and dynamic changes in endogenous release. When water bodies enter a turbid state and exhibit high endogenous loads, relying solely on water depth adjustment is often insufficient to simultaneously meet the multi-objective requirements of "improving the light environment, suppressing algae, inhibiting resuspension, and inhibiting endogenous release."

[0005] In addition, some existing technologies attempt to address biofilm or community structure degradation through "pulsed water level changes." For example, Chinese invention publication CN102518079A proposes a sluice gate ecological scheduling technology that facilitates the restoration and maintenance of riparian zones and submerged plant communities in sluice-controlled rivers. This technology includes "frequent pulsed increases and decreases in water level during summer" to maintain riparian plant structure and prevent biofilm growth on submerged plant surfaces, thereby improving survival rates. However, this approach is primarily geared towards seasonal scheduling regulations for sluice-controlled rivers. The triggering and amplitude / cycle parameters of the pulsed operation lack coupling constraints with water quality purification targets, resuspension risks, and endogenous release risks from sediment, making it difficult to directly apply to in-situ purification scenarios in eutrophic shallow lakes / reservoirs. Meanwhile, some patents propose a "monitoring-regulation" approach to improve the operation and maintenance of submerged plant systems. Chinese invention publication CN113567647A discloses a rapid monitoring system and regulation method for submerged plant communities. This system acquires information through detection and imaging and controls water replenishment and drainage facilities to regulate water depth and / or nutrient concentration. However, in eutrophic shallow water systems, the success or failure of remediation is often not determined by a single adjustment of water depth or nutrient concentration, but by the synergy between water level operation mode and endogenous control of sediment, resuspension risk constraints, and light compensation constraints. Existing solutions still lack an engineerable closed-loop operation strategy in the coupled chain of "endogenous release - resuspension - light environment - algal risk".

[0006] In summary, while existing submerged plant restoration and water purification technologies involve water level / depth regulation, species configuration, and monitoring management, they still generally suffer from several shortcomings under the complex conditions of eutrophic shallow water bodies. These include a lack of water level control centered on light compensation, a lack of online risk constraints addressing resuspension events, a lack of a process chain coordinated with the control of endogenous release from sediment, and a lack of a stable operating mechanism oriented towards water quality purification goals. These deficiencies make it difficult for submerged plant restoration to be stably transformed into sustainable water purification effects, necessitating the development of a method more suitable for in-situ ecological purification and restoration projects. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a closed-loop water level pulse method for the restoration of submerged communities, employing both optical compensation and resuspension dual constraints. The technical problem to be solved is as follows:

[0008] Existing submerged plant restoration projects mostly rely on empirical water level / depth regulation, lacking water level operation strategies constrained by underwater light compensation conditions. This results in low survival rates and difficulty in establishing stable communities in the early stages of planting due to fluctuations in transparency and shading.

[0009] Under the influence of wind, waves and construction disturbances, sediment resuspension causes a rapid increase in turbidity and triggers algal dominance. Existing methods lack online constraint and protection control mechanisms to address resuspension risks, making it difficult to maintain the stability of purification operations.

[0010] The continuous release of endogenous pollutants (especially phosphorus) from sediments can negate the water purification effect and induce repeated algal blooms. Existing technologies lack a closed-loop control method that couples endogenous pollution control processes with water level pulse operation, making it difficult to achieve the continuous purification goal of "suppressing endogenous pollution, improving transparency, and stabilizing the community".

[0011] To address the aforementioned technical challenges and achieve in-situ ecological purification of eutrophic shallow water bodies while improving the controllability and repeatability of submerged plant community restoration, this invention proposes a closed-loop regulation and restoration method. This method is centered on endogenous flux control and light compensation constraints, uses resuspension risk as the operational boundary, and employs the water level pulse curve as the primary control variable. The method is applicable to shallow water systems such as lakes, reservoirs, sluice-controlled river sections, and landscape water bodies. It achieves controllable water level regulation through gates, pumping stations, or storage facilities, uses submerged plant communities as biological purification units, and synergistically couples the sediment endogenous control process with water level operation, forming a process control chain of "monitoring—calculation—constraint—execution—feedback—rolling adjustment."

[0012] The method is preferably implemented in a systematic manner, and the system includes at least: a water level control unit for adjusting gate opening, pump station start / stop / frequency conversion, and water inflow / outflow of storage facilities to achieve the target water level curve; and a light field and turbidity monitoring unit for acquiring surface illumination. With / or underwater illumination profile ,transparency With / or turbidity Water quality monitoring unit, used to obtain chlorophyll content. Total phosphorus Total nitrogen Dissolved oxygen At least one or a combination of the following water quality purification characterization parameters; an endogenous monitoring unit for acquiring dissolved inorganic phosphorus in the overlying water. Pore ​​water dissolves inorganic phosphorus Redox potential at the sediment-water interface At least one or a combination of endogenous pollution characterization parameters; community monitoring unit for obtaining submerged plant cover. Community structure index The controller is used to receive monitoring data from each monitoring unit, perform constraint calculations, risk assessments and pulse parameter tuning, and output control commands to the water level execution unit.

[0013] Preferably, the monitoring data can be denoised and robustly processed, for example, by using moving average, robust filtering, or Kalman filtering to remove outliers; the turbidity change rate It can be obtained through differential calculation combined with smoothing to reduce false triggering caused by noise.

[0014] Regarding the setting of purification targets and constraint boundaries, the controller preferably establishes a set of purification control target thresholds and a set of endogenous control thresholds. The set of purification control target thresholds includes at least a transparency target threshold and an algae / nutrient control threshold (e.g., , , , , The target / trigger threshold); the set of intrinsic control thresholds includes at least the target / trigger threshold. , With / or The target / trigger thresholds, or combinations thereof, are used to constrain the risk of endogenous release from sediment. The established thresholds can be set based on regional water quality targets, engineering acceptance standards, historical baseline statistics, or rolling statistics during operation.

[0015] Regarding the establishment of light compensation constraints, this invention uses the compensating light intensity of the target submerged plant. As input, the calculation of light attenuation and light compensation depth is established, and the target water level zone is determined accordingly. .

[0016] Preferably, the light attenuation coefficient of the water body This can be obtained by fitting an exponential decay model, i.e.:

[0017]

[0018] And based on this, the light compensation depth is obtained. for:

[0019]

[0020] Transparency can also be used when there is a lack of illumination in the cross-section. Empirical conversion for estimating water body light attenuation coefficient (For example ,in (As an empirical coefficient), then calculate the optical compensation depth. .

[0021] Based on this, and based on the aforementioned optical compensation depth Target canopy height and safety margin Determine the target water level zone .

[0022] Preferably, the upper limit Meet the target canopy height from the water surface The optical path distance at the top is no greater than Among them, safety margin Desirable The lower limit The minimum water level is determined by combining shallow water stress, operational safety, and engineering boundary conditions, and is constrained by the minimum water level constraints to avoid exposure to the water surface, excessively shallow temperature stress, and / or operational safety.

[0023] Furthermore, when using multiple monitoring points At that time, each monitoring point can be Calculated optical compensation depth Take quantile value (For example To determine the upper limit To ensure at least The proportional monitoring points meet the light compensation constraints, thus forming an operating water level zone oriented towards spatial heterogeneity.

[0024] Based on the target water level zone The controller further selects the water level at the planting window. , benchmark operating water level and maintaining water level It is used for water level operation at different stages.

[0025] Regarding the planting and acclimatization strategies, this invention sets a low-water-level planting window and a gradual acclimatization stage to improve the success rate of colony establishment and reduce the risk of early shading. The low-water-level planting window refers to the water level at the planting window. Run and maintain the colonization window duration It is used to complete the release, planting, or propagation of submerged plant seed sources; during the planting period, a turbidity constraint is preferably set at [value missing]. When turbidity constraints are exceeded, extending the planting window, reducing the rate of water level change, or performing sediment consolidation / stabilization operations can be triggered. During the gradual acclimatization phase, the water level is raised from the planting window level... Adjust to the baseline operating water level And limit the rate of water level change to no more than the acclimatization limit. At the same time, at least one steady-state holding section is set. The preferred adjustment method is a "stepped gradual rise + platform maintenance" approach, ensuring that root anchorage and canopy elongation match water level changes. At the end of each steady-state segment, based on updated transparency... and / or underwater illumination profile Recalculate optical compensation depth and the target water level zone Compared with the benchmark operating water level Adjustments were made to ensure that the canopy of submerged plants continuously met the light compensation constraint throughout the acclimatization process.

[0026] Regarding the control of endogenous sediment sources, this invention couples the sediment blocking / stabilization process with water level operation as a pre- or parallel process to in-situ purification to suppress the interference of endogenous release on operation. The sediment blocking material preferably includes a phosphorus-controlling capping layer material, an isolation layer material, or a composite structure thereof; the sediment stabilization material preferably includes a solidification stabilization material, a flocculation-consolidation material, or a combination thereof.

[0027] Furthermore, the sediment blocking / stabilization process is preferably implemented before or during the subsequent gradual rise and acclimatization phase or the water level pulse phase to reduce hydrodynamic and resuspension risks; and a consolidation time is set. During the consolidation time The rate of change of internal water level shall not exceed the consolidation limit. (Preferably less than the domestication limit) This reduces the resuspension of fine particles after construction. The substrate blocking material includes a phosphorus-controlling coating material, an isolation layer material, or a composite structure thereof; the substrate stabilizing material includes a solidification stabilizing material, a flocculation-consolidation material, or a combination thereof; and the consolidation time... Water level change rate limit during the period Less than the domestication limit .

[0028] To achieve quantitative identification of endogenous risks, this invention preferably uses dissolved inorganic phosphorus in overlying water. Dissolved inorganic phosphorus in sediment pore water Redox potential at the sediment-water interface Constructing a risk-weighted indicator for endogenous release It can also introduce phosphorus diffusion flux at the sediment-water interface. Approximate calculations can be used as auxiliary criteria, for example:

[0029]

[0030] in, The equivalent diffusion coefficient; The thickness of the diffusion boundary layer;

[0031] When endogenous pollution characterization parameters or the phosphorus diffusion flux If the set of endogenous control thresholds is not met, supplementary substrate blocking / stabilization procedures or extended consolidation time may be performed. And if necessary, postpone entering the water level pulse phase.

[0032] Regarding the purification operation boundary between resuspension constraints and intrinsic constraints, this invention uses a "risk-weighted index + allowable upper limit" approach to achieve online constraint discrimination and configures protection strategies to ensure that the purification operation does not become unstable due to sudden disturbances.

[0033] Preferably, the resuspension risk-weighted index may be based at least on turbidity. With turbidity change rate The normalized weighted index is constructed, and an upper limit is set; the endogenous release risk weighted index can be based at least on , With / or The normalized values ​​are weighted and constructed, with an allowable upper limit set. The phosphorus diffusion flux can be superimposed if necessary. The normalization term is used to improve sensitivity. The allowable upper limit is determined based on the set of purification control target thresholds and the set of endogenous control thresholds. When any risk-weighted indicator reaches its allowable upper limit, or the turbidity change rate... Exceeding the threshold When this occurs, the controller enters a protection strategy, which includes, but is not limited to, limiting the rate of water level change. Reduce water level pulse amplitude, prolong the pulse rise / fall process, prolong the low water level residence time, suspend water level pulse and restore to the reference operating water level. This includes triggering or strengthening the endogenous control process of sediment, thereby controlling water level operation within the "dual boundary" of resuspension and endogenous release.

[0034] Regarding water level pulse operation, this invention uses water level curves. For the execution object, the water level pulse From parameter set Defined, respectively corresponding to pulse amplitude ,cycle Ascent time descent time High water level residence time and low water level residence time The pulse parameters. Water level curve. The expression is:

[0035]

[0036] In the formula, The baseline operating water level.

[0037] Preferably, water level pulse Asymmetric waveforms (e.g., rapid descent followed by slow ascent or slow descent followed by rapid ascent) are employed to improve the controllability of algae / attached biofilm disturbance. The range of pulse parameters can be set according to the project scale and water body response, and must meet certain requirements, such as the rise time. With descent time The ratio is not greater than or not less than Pulse amplitude Desirable ,cycle Desirable Low water level residence time Occupying the period of And can be achieved by extending the ascent time. or descent time Reduce the intensity of disturbance per unit time.

[0038] The water level pulse triggering condition is preferably associated with a set of purification control target thresholds. When the water quality purification characterization parameters deviate from the set of purification control target thresholds and / or the algae risk increases, the water level will be at the baseline operating water level. Superimposed water level pulse Forming a water level curve For example, when chlorophyll Total phosphorus Total nitrogen Increase or transparency Reduce dissolved oxygen When the water level falls below a threshold, a water level pulse phase is triggered; and the pulse parameters can be adjusted in conjunction with the situation where the weighted index of endogenous release risk exceeds the trigger threshold, or the endogenous control process of sediment can be prioritized. The triggering condition of "water quality purification characterization parameters deviating from the set of purification control target thresholds and / or increased algal risk" includes at least one of the following:

[0039] chlorophyll Above the trigger threshold, total phosphorus Above the trigger threshold, total nitrogen Above the trigger threshold, transparency Below the trigger threshold, dissolved oxygen Below the trigger threshold, and / or the endogenous release risk-weighted index The duration is above the trigger threshold and not less than .

[0040] Throughout the entire execution of the water level pulse phase, the controller simultaneously applies three types of constraints: firstly, the water level always meets the following conditions. The first is light compensation constraint; the second is that the resuspension risk weighted index is lower than the allowable upper limit; and the third is that the endogenous release risk weighted index is lower than the allowable upper limit, thereby ensuring that the pulse disturbance is executed within the purification operation boundary.

[0041] By applying three types of constraints, the disturbance of algae / attached biofilms is suppressed, shading is reduced, and transparency is improved, thereby increasing the efficiency of water purification.

[0042] To further enhance feasibility and verifiability, this invention can concretize the construction method of the "weighted index / comprehensive index" into the following calculation model and use it for controller operation judgment and rolling tuning, wherein the normalized quantity Interval normalization can be used, that is:

[0043]

[0044] Or baseline normalization, i.e.:

[0045]

[0046] in, It can be obtained from historical monitoring statistics, engineering design boundaries, or rolling updates during the operation period; To repair the baseline mean or median.

[0047] Therefore, the resuspension risk weighted index It is preferred to construct it according to the following formula, namely:

[0048]

[0049]

[0050] in, Indicates the turbidity after normalization; This represents the rate of change in turbidity after normalization. All are weighting coefficients, and ;

[0051] Endogenous release risk-weighted index It is preferred to construct it according to the following formula, namely:

[0052]

[0053] in, This indicates the dissolved inorganic phosphorus in the overlying water after normalization; This represents the difference between dissolved inorganic phosphorus in sediment pore water and dissolved inorganic phosphorus in overlying water after normalization. This represents the normalized redox potential of the sediment-water interface; All are weighting coefficients, and ;

[0054] And the normalized phosphorus diffusion flux can be As an additional item, it is incorporated into the weighted index of endogenous release risk. In order to improve the sensitivity to changes in endogenous flux.

[0055] Comprehensive indicators of water purification operation It is preferred to construct it according to the following formula, namely:

[0056]

[0057] in, Indicates the normalized transparency; This represents the normalized dissolved oxygen. This represents the normalized chlorophyll content; , This represents the normalized total phosphorus and total nitrogen; These are the weighting coefficients, and ;

[0058] Endogenous control comprehensive index It is preferred to construct it according to the following formula, namely:

[0059]

[0060] in, This indicates the dissolved inorganic phosphorus in the overlying water after normalization; This represents the difference between dissolved inorganic phosphorus in sediment pore water and dissolved inorganic phosphorus in overlying water after normalization. Indicates the turbidity after normalization; These are the weighting coefficients, and .

[0061] In this invention, the weights can be set according to the functional objectives of the water body, sensitive indicators, and the stage of engineering operation, and can be updated in rolling adjustments to adapt to changes in operating conditions. The above formula is a preferred embodiment used to improve the controller's quantitative characterization of the coupling relationship between "resuspending-internal source-light environment-water quality," and does not constitute a limitation on the scope of protection of this invention.

[0062] Regarding closed-loop rolling tuning, this invention uses a rolling period. Update the pulse parameters. Specifically, in each rolling cycle... Internal coverage acquisition Community structure index Water quality purification characterization parameters and endogenous pollution characterization parameters are used to construct a comprehensive index for water body purification operation. Comprehensive indicators of endogenous control and use it as a parameter set. Compared with the benchmark water level The basis for adjustment;

[0063] Preferably, the controller can use constrained model predictive control, response surface model, or historical data-based predictive model to update the parameter-response relationship, while satisfying the light compensation constraint. Resuspension constraints and intrinsic constraints Determine the next rolling period under the condition of parameter set Compared with the benchmark operating water level .in, , These are the comprehensive indicators of water purification operation. Comprehensive indicators of endogenous control The maximum allowed limit.

[0064] Furthermore, the rolling adjustment target can be expressed as a comprehensive indicator for improving the water purification operation. Increase and make the comprehensive index of endogenous control Reduced multi-objective constraint optimization, or equivalent construction of a single objective function. ,Right now:

[0065]

[0066] in, These are the weighting coefficients, and ;

[0067] And based on this, the parameter set Compared with the benchmark operating water level Update the parameters while ensuring that operational constraints are not exceeded. When the comprehensive indicators for water purification operation... Achieving the set of purification target thresholds and the comprehensive indicators of endogenous control Reaching the set of intrinsic control target thresholds and continuously satisfying no less than [a certain number of] [thresholds]. One rolling cycle When the water level pulse stops, the controller switches the water level to the maintenance level. Entering the purification maintenance phase. During the purification maintenance phase, monitoring continues, and when the triggering conditions reappear, the water level pulse phase can be restarted to achieve full-cycle operation control.

[0068] By employing the above technical solution, the present invention provides a method for the restoration of submerged communities by a closed-loop pulsed water level system under dual constraints of light compensation and resuspension, which has at least the following beneficial effects:

[0069] 1. This invention uses light-compensated depth constraints to determine the target water level zone and combines a low-water-level planting window with a water level operation strategy of gradual rise and acclimatization to match the submerged plant community establishment process with the underwater light environment, significantly reducing the risk of restoration failure caused by transparency fluctuations and shading, and improving the stability and replicability of in-situ ecological purification operation.

[0070] 2. This invention couples the sediment endogenous control process with water level operation and introduces a dual-risk online constraint and protection strategy for resuspension and endogenous release. This can effectively suppress the rebound impact of turbidity surge and endogenous phosphorus release caused by disturbance on water quality, reduce the probability of cyanobacterial bloom recurrence, and improve the sustainability of water purification.

[0071] 3. This invention adopts a water level pulse parameterized control and rolling closed-loop tuning mechanism, which transforms water level control from empirical operation to quantifiable and iterative process control. It can achieve the synergistic goals of improving transparency, inhibiting algae and restoring submerged communities under different water bodies and working conditions, making it easy to promote and apply in engineering projects. Attached Figure Description

[0072] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0073] Figure 1 This is a flowchart of the water level pulse closed-loop submerged community restoration method in this invention;

[0074] Figure 2 This is a schematic diagram of the overall structure of the water level pulse closed-loop submerged community restoration system in this invention;

[0075] Figure 3 This is a schematic diagram of the water level pulse closed-loop submerged community restoration system of the present invention;

[0076] Figure 4 This is a cross-sectional schematic diagram of the substrate blocking / stabilizing structure and endogenous flux suppression in this invention. Detailed Implementation

[0077] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This will allow for a full understanding of how the present application uses technical means to solve technical problems and achieve technical effects, and to facilitate its implementation.

[0078] Example 1: Process verification in a typical water body.

[0079] This embodiment selects a controllable water level regulating lake in a certain city as the object, with a water surface area of ​​approximately 10.5 hm². 2 The lake has an average depth of approximately 1.4 meters and a maximum depth of approximately 2.1 meters. It is connected to an external river via a pump gate, enabling daily water level regulation. A 1.8-hectare area of ​​gentle near-shore slope was selected. 2 As the submerged plant restoration and purification operation zone, the bottom sediment of the restoration zone is mainly silt-clay, with a surface organic matter content of approximately 4.6%. Resuspension due to wind and wave disturbance is significant. For ease of control and calculation, the water level in this embodiment is... Defined as the water depth from the water surface to the bottom sediment surface at the representative cross section of the recovery zone.

[0080] The monitoring system employs a combination of online continuous monitoring and laboratory verification. Online monitoring includes: surface illumination. underwater illumination profile (depth (0.3, 0.6, 0.9, 1.2 m), turbidity (Sampling interval of 10 min), dissolved oxygen (Sampling interval of 10 min), chlorophyll (30-minute sampling interval); Transparency Measurements were taken daily from 10:00 to 11:00 using a Seymour disk and compared with turbidity. Cross-checking. Laboratory monitoring includes testing total phosphorus twice weekly. Total nitrogen Dissolved inorganic phosphorus in sediment pore water is determined once a week by sampling the sediment pore water (sampling depth 0–5 cm). Simultaneous determination of dissolved inorganic phosphorus in overlying water The redox potential of the sediment-water interface was measured in situ at the sediment-water interface. Submerged plant cover Underwater video frame segmentation identification method (once a week), community structure index The Shannon index, based on relative species cover, was used for calculations (every two weeks).

[0081] In this embodiment, *Vallisneria natans* was selected as the dominant species, supplemented by *Hydrilla verticillata* as a secondary seed source to compensate for light intensity. Take 30 μmol·m -2 ·s -1 (Determined based on actual measurements in the region during spring and summer and the adaptability of the seed source). In the initial stage of operation (day 0), the average effective surface light intensity from 10:00 to 14:00 on a sunny day was taken as the surface light intensity. (This embodiment takes) μmol·m -2 ·s -1 ), and obtain underwater profile illumination. As shown in Table 1, the light attenuation coefficient of the water body was obtained by fitting an exponential decay model. The model expression is:

[0082]

[0083] Will For depth Perform linear regression (fitting through the origin) to obtain the light attenuation coefficient of the water body. Based on this, the optical compensation depth is calculated. for:

[0084]

[0085] To reflect spatial differences, facilities were deployed in the restoration area. At each optical field monitoring point, the optical attenuation coefficient was calculated using the same method. With light compensation depth Obtain the light compensation depth The range is 0.993–1.211 m. To ensure that most monitoring points meet the light compensation constraint, this embodiment uses a conservative quantile value. (Corresponding to a satisfactory level for at least approximately 80% of monitoring points). Target canopy height. Safety margin The target water level will have an upper limit. The optical path from the water surface to the top of the canopy is no greater than [amount missing]. Determined, that is:

[0086]

[0087] target water level zone lower limit Considering the requirements of shallow water thermal stress, operational safety, and preventing water surface exposure, the target water level was determined to be 0.60m. Therefore, the target water level zone in this embodiment is... Based on this, the water level for planting windows was selected. , benchmark operating water level Maintain water level .

[0088] Table 1. Light field data and calculation of light compensation depth (representative points in the recovery zone)

[0089]

[0090] After completing baseline monitoring from day 0 to day 6, the controller sequentially implemented the following steps according to the method of this invention: low water level planting window, endogenous sediment control, gradual rise acclimatization, water level pulse disturbance, and rolling adjustment. Seed stock was a combination of *Vallisneria natans* rhizome seedlings and *Hydrilla verticillata* bundle seedlings: 18 *Vallisneria natans* plants per m². -2 Hydrilla verticillata 6 bundles·m -2 Biodegradable fixing clips and small-scale grid positioning are used to avoid initial drift. During the planting window, the water level is stabilized at the planting window level. Continuous planting window duration and constrained by turbidity As a constraint for purification operation during the planting period; when online turbidity When the threshold is approached, disturbance input is suppressed by reducing the pump gate regulation rate and briefly stopping the external water supply.

[0091] Endogenous phosphorus control in the sediment is implemented in the later stages of the low-water-level planting window to reduce hydrodynamic diffusion. This embodiment employs a combination of a "phosphorus-controlling blocking layer + stabilizing consolidation layer," where the phosphorus-controlling blocking material is a composite powder of iron-modified clay and aluminosilicate minerals (mass ratio 7:3), added at a rate of 1.8 kg·m³. -2 A thin layer of quartz sand with a particle size of 0.5–1.0 mm, approximately 15 mm thick, is applied on top to improve its resistance to resuspension. A consolidation time is set after construction. And limit the rate of water level change to a consolidation limit. To ensure a near-constant water level during the consolidation period. Internal monitoring of dissolved inorganic phosphorus in the overlying water. Dissolved inorganic phosphorus in sediment pore water Redox potential at the sediment-water interface Criterion: If at the end of the consolidation period No decline or If the level remains significantly high, then supplementary thin-layer deposition should be performed and the consolidation time extended. .

[0092] During the gradual acclimatization stage, the water level will be raised from the planting window level. Stepwise rise to the benchmark operating water level Control the rate of water level change to not exceed the acclimatization limit. And set a steady-state holding section. The specific operation is as follows: 0.65m (consolidation complete) → 0.75m (hold for 5 days) → 0.85m (hold for 5 days) → 0.95m (hold for 10 days). Each steady-state holding period... Recalculate the light attenuation coefficient of the water body at the end. With light compensation depth If light compensation depth The drop caused the upper limit of the target water level zone to be reached. If the water level contracts, the benchmark operating level will be lowered simultaneously. Or suspend the water level rise.

[0093] Entering the high-risk period of summer (starting from day 63), when chlorophyll is detected... Rising and transparency The value decreases and deviates from the set of purification control target thresholds (in this embodiment, the trigger threshold is used). or or When [the water level] is activated, a water level pulse disturbance is initiated. Water level pulse Use parameter set In this embodiment, the initial setting is: pulse amplitude ,cycle rapid precipitation Low water level Slowly rising water High water level And always satisfy the water level curve Light compensation constraint (i.e., reference operating water level) Baseline operating water level (All are within the target water level zone).

[0094] To improve feasibility, this embodiment employs an online constraint method of "weighted risk index + allowable upper limit" for resuspension and endogenous release, and uses a comprehensive index for rolling adjustment of the purification status. Baseline normalization is used for normalization. ,in The baseline average for days 0-6 (baseline in this example: , , , , , , , , Resuspension risk-weighted index Preferred by With turbidity change rate normalized quantity Weighted construction, i.e.:

[0095]

[0096] This embodiment takes And set the allowed limit. At the same time, the turbidity change rate is set. threshold Endogenous release risk-weighted indicator Preferred from normalized , and Weighted construction, i.e.:

[0097]

[0098] This embodiment takes And set the allowed limit. .

[0099] Comprehensive indicators of water purification operation The preferred method is to construct a weighted average of endogenous pollution characterization parameters such as transparency, dissolved oxygen, and algae / nutrients, i.e.:

[0100]

[0101] This embodiment takes And set the purification target threshold. .

[0102] Endogenous control comprehensive index Preferred from normalized , and Weighted construction, i.e.:

[0103]

[0104] In this embodiment, the weights are respectively... , , And set the endogenous control threshold. In addition, community recovery indicators In terms of coverage With diversity index The configuration in this embodiment is based on target coverage. With goal diversity After normalization, weighting was performed (coverage weight 0.6, diversity weight 0.4), and a threshold was set. .

[0105] Setting the rolling period Take each rolling cycle. Finally, if the comprehensive indicators of water purification operation The indicator did not improve or even declined, and the risk-weighted indicator was resuspended. Weighted index of endogenous release risk If the value is below the upper limit, then shortening the cycle is the preferred method. Increase the retention time at low water levels Or fine-tune the pulse amplitude To enhance disturbance to algae / biofilms; if... or or Then the protection strategy is activated, which includes at least reducing the pulse amplitude. Extend the ascent time With / or descent time Extend the steady-state maintenance period Or pause the pulse and return to the baseline operating level. When necessary, strengthen the process of controlling the internal sources of sediment pollution.

[0106] Baseline (day 0) monitoring results showed: , , , , , , , , Calculated using the above weights and baseline normalization. , , , Coverage and diversity have not yet been achieved. ).

[0107] After the planting window and consolidation period (day 28), water quality and endogenous indicators showed a synchronous improvement trend, with transparency increasing. The turbidity rose to 0.70m. Chlorophyll dropped to 11 Down to Total phosphorus Down to Water-soluble inorganic phosphorus on top Down to Redox potential at the sediment-water interface Rise to The comprehensive indicators of water purification operation were calculated. Comprehensive indicators of endogenous control Endogenous release risk weighted index coverage diversity Community recovery indicators Gradually raise and acclimatize to the baseline operating water level. (After day 56) Comprehensive indicators of water purification operation Increased to 0.431, the comprehensive index of endogenous control The coverage dropped to 0.563. It rose to 0.32.

[0108] During the high-temperature period (day 63), there was a brief increase in algae and a decrease in transparency (chlorophyll content). ,transparency The water level pulse was initiated according to the trigger threshold. A strong wind event occurred during the pulse execution (13:00–16:00 on day 76), and turbidity was monitored online. The turbidity rate increased rapidly from 10 to 26. Calculate the resuspension risk weighted index using the method described above. The controller immediately implements a protection strategy: suspending the rising phase of the current pulse and maintaining the water level at 0.78m, waiting for the turbidity to decrease within 24 hours. After falling below 12, the pulse is restored, but the pulse amplitude A is reduced from 0.25m to 0.15m, and the rise time is adjusted. The duration was extended from 5 days to 7 days to reduce the risk of resuspension; the resuspension risk weighted index was then applied to the subsequent two periods. It remained below 0.60 and did not cross the boundary again.

[0109] Table 2 presents the monitoring data and indicator calculation results at key time points. It can be seen that after pulse operation and rolling adjustment (day 98), the comprehensive indicators of water purification operation... Endogenous control comprehensive index Community recovery indicators And the water level remained stable for two consecutive rolling cycles, so the water level pulse was terminated and the water level was switched to a maintenance level. During the maintenance phase (days 112-126), the indicators remained stable, and the overall water purification operation indicators... The comprehensive index of endogenous control remained between 0.64 and 0.66. The coverage of submerged plants should be maintained between 0.42 and 0.44. It reaches 0.55 or higher.

[0110] Table 2. Monitoring and Indicator Calculation Results During Operation (Key Time Points)

[0111]

[0112] This embodiment fully demonstrates the following operational framework: determining the target water level zone based on light compensation depth and constructing a planting window—gradual ascent acclimatization—water level pulse curve. Combined with sediment blocking / stabilization processes and dual risk constraints and protection strategies of resuspension and endogenous release, it achieves in-situ ecological purification of eutrophic shallow water bodies and stable restoration of submerged plant communities.

[0113] Example 2: Synergistic control of sediment endogenous sources under high endogenous load conditions.

[0114] This embodiment selects a semi-enclosed bay area of ​​a large shallow lake as the object, with a water surface area of ​​approximately 4.6 hectares. 2 The average water depth is approximately 1.0 m, with a maximum depth of approximately 1.4 m. The water exchange capacity is weak, and the bottom sediment contains high levels of organic matter and reactive phosphorus. In summer, bottom hypoxia is prone to occur, accompanied by continuous release of endogenous phosphorus, manifesting as low transparency, high algae levels, and recurring algal blooms. The bay area is connected to the outer river via a controllable gate pump, providing daily-scale water level regulation capabilities. To highlight the synergistic effect of endogenous sediment control and water level operation, this embodiment sets up two adjacent operating zones within the bay area, achieving weak water exchange through flexible enclosures: Zone A (area 0.40 hm²) 2 The process of controlling the endogenous source of sediment and implementing closed-loop regulation of water level pulses according to the present invention is carried out in Zone B (area 0.40 hm²). 2 Maintaining the same seed source placement and water level control framework, but without implementing sediment blocking / stabilization material construction, is used to compare the impact of endogenous load on purification operations. Water levels in both zones. The definition of each is the water depth from the water surface to the bottom sediment surface at the representative cross section of the operating area.

[0115] Monitoring employs a combination of online continuous monitoring and laboratory verification. Online monitoring includes: surface illumination. underwater illumination profile (depth (0.3, 0.6, 0.9, 1.2 m) turbidity (10-minute sampling interval), dissolved oxygen (10-minute sampling interval), chlorophyll (30-minute sampling interval); Transparency Measured daily at 10:00–11:00 using a Seymour disk and compared with turbidity. Cross-checking. Laboratory monitoring includes testing total phosphorus twice weekly. Total nitrogen Pore ​​water (0–5 cm) was collected synchronously once a week to determine dissolved inorganic phosphorus in the pore water. Collect overlying water samples and determine dissolved inorganic phosphorus in the overlying water. The redox potential of the sediment-water interface was measured in situ at the sediment-water interface. Submerged plant cover Underwater video segmentation recognition (once a week) was used to analyze the community structure index. The Shannon index, based on relative species cover, was used (once every two weeks).

[0116] In this embodiment, *Vallisneria natans* is the dominant species, supplemented by *Hydrilla verticillata* as a secondary seed source to compensate for light intensity. Take 30 μmol·m -2 ·s -1 The baseline period (days 0–6) was defined as the effective average surface illumination during sunny days from 10:00 to 14:00. Measured surface illumination at representative point μmol·m -2 ·s -1 underwater illumination profile The values ​​were 210, 75, 26, and 9 μmol·m, respectively. -2 ·s -1 (Corresponding to 0.3, 0.6, 0.9, and 1.2 m). The light attenuation coefficient of the water body was obtained by fitting an exponential decay model. The model expression is:

[0117]

[0118] right With depth The light attenuation coefficient of the water body was obtained by fitting through the origin. Based on this, the optical compensation depth is calculated. ,Right now:

[0119]

[0120] Five light field monitoring points were set up in the operating area. The optical compensation depth was calculated using the same method. The depth is 0.74–0.89 m. To ensure that most monitoring points still meet the light compensation constraint under water level fluctuations and short-term turbidity, this embodiment adopts a conservative light compensation depth. (Equivalent to taking a conservative value from the lower quantile), take the target canopy height. Safety margin The upper limit of the initial target water level zone. for:

[0121]

[0122] Lower limit of the initial target water level zone Considering both preventing excessively shallow thermal stress and operational safety, the initial target water level zone was determined to be 0.55m. Based on this, the water level at the planting window is set. Initial benchmark operating water level Maintain water level .

[0123] As operation progresses, the controller measures the light attenuation coefficient of the water body at the end of each steady-state phase. With light compensation depth Updated on a rolling basis. On day 28, the measured surface illumination at the representative point in area A was recorded. μmol·m -2 ·s -1 underwater illumination profile The values ​​were 330, 185, 104, and 58 μmol·m. -2 ·s -1 The corresponding fitted water light attenuation coefficient Calculate the optical compensation depth Surface illumination of area B (representative point) μmol·m -2 ·s -1 underwater illumination profile The values ​​were 250, 95, 36, and 13 μmol·m. -2 ·s -1 The corresponding fitted water light attenuation coefficient Calculate the optical compensation depth Due to improved water clarity in Area A, the conservative light compensation depth has been adjusted upwards accordingly, theoretically increasing the upper limit. The target water level is adjusted upwards to above 1.2m; considering the topographical boundaries of the bay area and the requirements for steady-state operation, this embodiment updates the upper limit of the target water level zone in Area A. The reference water level for Zone A is set at 1.25m, and the corresponding operating water level for Zone A is increased from 0.85m to 1.00m. Due to significant fluctuations in turbidity in Zone B, this embodiment increases the safety margin to [missing information]. And maintaining a conservative water level zone constraint, Zone B will remain unchanged. Target water level zone and benchmark operating water level The benchmark water level is being maintained.

[0124] Table 3 Calculation of optical field parameters and optical compensation depth (key time points)

[0125]

[0126] After baseline monitoring ended (starting from day 7), both areas simultaneously entered the planting window, and the water level was stably controlled at the planting window level. Run and maintain duration Seed stock was released using a combination of *Vallisneria natans* rhizome seedlings and *Hydrilla verticillata* bundle seedlings: 20 *Vallisneria natans* plants per m². -2 8 bundles of black algae·m -2 Biodegradable fixing clips and grid positioning were used to improve the initial fixation success rate. Turbidity constraints were set during the planting period. In the event of a sudden disturbance, the rate of water level change should be reduced and unnecessary water replenishment and drainage operations should be suspended to maintain a low-disturbance environment.

[0127] In Area A, during the mid-term of the planting window (days 10-11), a sediment-based internal control process was implemented to reduce the risks of construction-induced diffusion and resuspension. The sediment-blocking material used was a composite powder of iron-modified clay and aluminosilicate minerals (mass ratio 7:3), applied at a rate of 2.2 kg / m³. -2 This creates a continuous barrier layer on the sediment surface; a thin layer of quartz sand (0.5–1.0 mm particle size, approximately 20 mm thick) is then laid on top to enhance its resistance to resuspension. A consolidation time is set after construction. The rate of water level change during the consolidation period shall not exceed the consolidation limit. During the consolidation period, priority should be given to maintaining a constant water level and reducing external disturbance input; at the end of the consolidation period and If the intrinsic control threshold set is not met, an additional 0.6 kg·m³ of blocking material should be added. -2 The consolidation period was extended by 5 days. In this embodiment, the threshold requirement was met in area A on the 24th day of the re-monitoring, and no additional addition was made; no blocking / stabilization construction was implemented in area B.

[0128] After the consolidation period, both zones entered a gradual acclimatization phase. Zone B operated according to the initial target water level zone, gradually raising the water level from 0.60m to the benchmark operating water level in steps. The rate of water level change is limited to not exceeding the acclimatization limit. And set a steady-state holding section. After completing the light compensation depth update on day 28, the baseline operating water level in Area A was raised. Using the same rate limit and steady-state holding section The water level was raised from 0.60m to 1.00m to allow the canopy growth to match the water level changes; meanwhile, the light attenuation coefficient of the water body was recalculated at the end of each steady-state section. With light compensation depth And based on this, examine the water level curve. Light compensation constraints.

[0129] To quantify the controllability of endogenous phosphorus release from sediment, this embodiment uses a concentration gradient plus an equivalent diffusion coefficient to estimate the phosphorus diffusion flux at the sediment-water interface. Approximate quantity:

[0130]

[0131] in, For the diffusion boundary layer thickness, this embodiment takes... The equivalent diffusion coefficient of the bottom sediment pore medium was taken in the control area (area B). (Estimated based on commonly used engineering values ​​for fine-grained sediment in shallow bay areas, combined with porosity and tortuosity). In area A, after the formation of the barrier layer, the equivalent diffusion coefficient is calculated by converting the barrier layer's porosity and tortuosity: the molecular diffusion coefficient is used. Porosity of the barrier layer , tortuosity Then the equivalent diffusion coefficient for:

[0132]

[0133] In this embodiment, the equivalent diffusion coefficient is used. Convert the above flux to At that time, adopt and The conversion relationships are clear, and the calculation process can be directly verified.

[0134] Regarding operational constraints, the controller constructs online resuspension risk-weighted indicators and endogenous release risk-weighted indicators, and sets allowable upper limits; if either risk indicator exceeds the limit or the turbidity change rate... Exceeding the threshold When the water level pulse amplitude is activated, the protection strategy includes at least reducing the pulse amplitude, extending the rise / fall process, extending the low water level residence time, or pausing the pulse and returning to the baseline operating water level. If necessary, the process of controlling the internal sources of sediment pollution should be strengthened in conjunction with other measures. For ease of verification, baseline normalization is used in this embodiment. ( (Baseline mean from day 0 to day 6), and provides a set of preferred calculation methods: resuspension risk weighted index for:

[0135]

[0136]

[0137] in, .

[0138] Endogenous release risk-weighted index for:

[0139]

[0140] in, .

[0141] Comprehensive indicators of water purification operation Comprehensive indicators of endogenous control They are respectively:

[0142]

[0143]

[0144] in, , .

[0145] This embodiment sets a purification target threshold. Endogenous control target threshold and with coverage Community Index Constructing community recovery indicators (Target , (Weight 0.6 / 0.4), set The rolling period is taken Continuously satisfy no less than After one rolling cycle, it switches to the maintenance phase.

[0146] After entering the high-risk period in summer, when chlorophyll or total phosphorus Trigger threshold, or transparency Below the threshold, or the comprehensive indicators of water purification operation If the target water level is not met, a water level pulse will be activated. Area A will use pulse parameters under the updated target water level zone constraints. And ensure the water level curve Always in Due to light compensation constraints and turbidity fluctuations in area B, the pulse amplitude is automatically limited to the specified value under the controller's constraints. To ensure .

[0147] Table 4 presents the monitoring data and verifiable calculation results at key time points for the two zones. At baseline, the two zones were consistent, with dissolved inorganic phosphorus in the sediment pore water. High sediment-water interface redox potential Low, estimated phosphorus diffusion flux Approximately 14.49 mg·m -2 ·d -1 After the blocking / stabilization process is implemented and solidified in area A, inorganic phosphorus is dissolved in the overlying water. , and All decreased significantly, and the equivalent diffusion coefficient was reduced due to the blocking layer. Decrease, estimating phosphorus diffusion flux It decreased to 3.83 mg / m³ on day 14. -2 ·d-1 On day 56, the level decreased to 2.29 mg / m³. -2 ·d -1 Area B did not implement endogenous control measures, resulting in high phosphorus diffusion flux. Maintaining at 12 mg / m -2 ·d -1 Around, total phosphorus in water With chlorophyll The decline is slow. Meanwhile, the transparency of Area A is... Improved underwater light environment reduces water light attenuation coefficient Significantly reduced light compensation depth This allows for raising the baseline operating water level. And implement more effective pulse operation; Zone B is limited by light compensation constraints and turbidity fluctuations, and both water level operation space and pulse amplitude are limited. According to the threshold criterion of this embodiment, Zone A has met the requirements on the 56th day. , and After stabilizing for two consecutive rolling cycles, it switches to maintaining the water level. Operation; Zone B still failed to reach the endogenous control threshold and purification control target threshold by day 70.

[0148] Table 4. Monitoring data and calculation results at key time points in the two regions (including flux estimation and indicators)

[0149]

[0150] As can be seen from this embodiment, under the operating conditions of a bay area with high endogenous phosphorus load, the synergistic coupling of sediment blocking / stabilization process and water level operation can significantly reduce the driving force of endogenous release and expand the water level operation space that can meet the light compensation constraint, thereby enabling water level pulse regulation to be stably executed within the boundary between resuspension and endogenous risk; by rolling adjustment, after the comprehensive indicators of purification operation and the comprehensive indicators of endogenous control reach the threshold, the process switches to the maintenance stage, forming a complete in-situ ecological purification closed-loop operation process.

[0151] Example 3: Resuspension boundary and protection strategy in strong winds and waves / easily resuspensible waters.

[0152] This embodiment demonstrates in-situ ecological purification operation verification in the nearshore zone of a shallow-water regulating reservoir characterized by strong wind and wave disturbances and frequent resuspension events. The reservoir serves as a backup water source for the city, with a surface area of ​​approximately 32 hectares. 2 The effective wind distance from the prevailing wind direction is approximately 2.3 km. The nearshore seabed is mainly composed of silt to fine sand, with a median grain size of approximately [missing information]. Under the influence of wind and waves, significant shear stress occurs in the bedrock, often resulting in a short-term process of rapid turbidity increase followed by a sharp drop in transparency and then a resurgence of algae. The reservoir achieves daily water level regulation through gates and pumping stations, with the normal operating water depth controllable within the range of 0.6–1.6 m. This embodiment selects approximately 1.20 hm² of gentle slope on the south bank. 2 As a recovery and purification operation area, it is divided into two adjacent operation units by flexible enclosure: Zone C (area 0.30 hm²) 2 The resuspension risk constraint + protection strategy + rolling adjustment of this invention are enabled; D area (area 0.30hm) 2 Under the same seed source release and water level pulse framework, without enabling resuspension risk boundary and protection strategies, the impact of resuspension boundary control on operational stability was compared. Water levels in the two zones... Both are defined as the water depth from the water surface of the cross section to the surface of the bottom sediment.

[0153] Monitoring employs a combination of online continuous monitoring and laboratory verification. Online monitoring includes: surface illumination. underwater illumination profile (Depths of 0.3, 0.6, 0.9, and 1.2 m, recorded over 10 minutes), turbidity (10-minute sampling interval), dissolved oxygen (10-minute sampling interval), chlorophyll (30-minute sampling interval); Transparency Measured daily at 10:00–11:00 using a Seymour disk and compared with turbidity. Cross-checking. Laboratory monitoring includes testing total phosphorus twice weekly. Total nitrogen Pore ​​water (0–5 cm) was collected weekly to determine dissolved inorganic phosphorus in the sediment pore water. Simultaneously collect overlying water samples to determine dissolved inorganic phosphorus in the overlying water. The redox potential of the sediment-water interface was measured in situ at the sediment-water interface. Submerged plant cover Underwater video frame segmentation identification method (once a week), community structure index The Shannon index, based on relative species cover, was used (once every two weeks).

[0154] Both areas share the same provenance, with Vallisneria natans as the dominant species, supplemented by Hydrillaverticillata to aid in community building. The goal is to compensate for light intensity. During the baseline period (days 0–6), the effective average light intensity from 10:00 to 14:00 on sunny days was selected as the surface light intensity. (Representative point) Underwater illumination profile They are respectively , , , The light attenuation coefficient of water body was obtained by fitting an exponential decay model. The model expression is:

[0155]

[0156] right With water depth The light attenuation coefficient of the water body was obtained by fitting through the origin. Based on this, the optical compensation depth is calculated. ,Right now:

[0157]

[0158] Take the target canopy height Safety margin The initial target water level has an upper limit. for:

[0159]

[0160] Initial target water level lower limit Combining shallow thermal stress with operational safety Therefore, the initial target water level zones for the two areas are: Based on this, the water level at the planting window is set. Initial benchmark operating water level Maintain water level And require all subsequent water level curves to meet the following conditions. And at the end of the steady-state phase, based on the updated surface illumination... Underwater illumination profile or transparency Recalculate the light attenuation coefficient of the water body With light compensation depth Target water level zone with rolling correction .

[0161] From day 7 to day 27, both areas simultaneously entered the low-water-level planting window, with the water level remaining constant during the planting window. Continuous planting window water level The planting density of *Vallisneria natans* rhizome seedlings was 18 plants per square meter. -2 Hydrilla verticillata seedling density: 6 bundles / m -2 Biodegradable fixing clips and grid positioning are used to reduce drift caused by wind and waves. Turbidity operation constraints are set during the planting period. When turbidity When the water level approaches the threshold, reduce the frequency of water replenishment and drainage operations and avoid rapid water level changes.

[0162] To minimize the impact of endogenous release on purification operations, a thin-layer substrate stabilization / blocking process was implemented in both zones during the middle of the planting window (this was consistent across both zones to eliminate the influence of endogenous differences on the "resuspension boundary control" theme of this embodiment): 1.5 kg·m³ of iron-modified clay was used. -2 As a phosphorus-controlling material, it is coated with a thin layer of quartz sand (particle size 0.5-1.0 mm, thickness approximately 15 mm) to enhance its anti-resuspension stability; a consolidation time is set after construction. During the consolidation period, the rate of water level change should not exceed [a certain percentage]. After consolidation, both zones entered a gradual acclimatization phase: the water level was raised in steps from 0.70m to the baseline operating level. Domestication limits that restrict the rate of domestication A steady-state maintenance section is set for every 0.10m increase in elevation. The light attenuation coefficient of the water body is updated at the end of each steady-state segment. Light compensation depth With the target water level zone On day 28, the surface illumination of the light field at the representative point in area C was updated. The underwater illumination profile is as follows: , , , The light attenuation coefficient of the water body was obtained by fitting. Calculate the optical compensation depth This indicates an increase in the optical compensation margin, providing a feasible basis for subsequent protective water level adjustments without violating optical compensation constraints.

[0163] The risk of algae blooms increases during periods of high temperatures (in this embodiment, the trigger threshold is chlorophyll). or transparency or total phosphorus At that time, water level pulse disturbances were initiated in both zones, and the water level curves were as follows:

[0164]

[0165] The initial pulse parameters are set as follows: pulse amplitude ,cycle Rapid precipitation Low water level stay Slow rise in water level High water level stay Therefore, the low water level is used as the benchmark operating water level. The high water level is the benchmark operating water level. All of them satisfy the initial target water level zone constraint. .

[0166] Region C employs a resuspension risk boundary and protection strategy during pulse operation. For ease of verification, baseline normalization is used in this embodiment. ,in The baseline mean (in this embodiment) ), and used turbidity and turbidity abrupt changes to characterize resuspension risk: turbidity change rate (Unit: NTU·h) -1 Normalization ,in (Taking the high quantile rate of change of the baseline period and historical operation as the scale constant), a resuspension risk weighted index is then constructed. ,Right now:

[0167]

[0168] Set the maximum allowed limit and set a direct threshold. When satisfied or At that time, Zone C immediately enters a protection strategy, which includes at least: suspending the continued rapid precipitation and low water level of the current pulse, switching the water level to a protective steady-state level (preferably a higher water level within the allowable range of light compensation constraints to reduce bed shear), and reducing the pulse amplitude of the next cycle. Extend the ascent time With / or descent time Shorten the residence time at low water levels In addition, a steady-state maintenance section is added, and the water body light attenuation coefficient is updated continuously. With light compensation depth To verify the new target water level zone And avoid exceeding the light compensation constraint for relevance.

[0169] On the 52nd day, Zone C was in a period of pulsating low water levels. A strong wind and wave event lasting 4 hours occurred. Hourly turbidity in area C. The changes and risk calculations are shown in Table 5: Turbidity at 12:00 The turbidity rose to [a certain level] by 16:00. And the hourly turbidity change rate at 16:00 Resuspension risk weighted index This triggered a protection strategy. Starting at 16:10, the controller suspended the continued low water level and subsequent rapid rainfall, transitioning to a protective steady-state operation. It also refitted the light attenuation based on the real-time light field: average surface illumination from 16:30 to 18:00 on the day of the event. underwater illumination profile for: , , , The light attenuation coefficient of the water body was obtained by fitting. Calculate the optical compensation depth Based on this, the upper limit of the target water level for the day will be set. Temporary convergence Therefore, the protective steady-state water level is set as follows: (Located after convergence) (Inner), and maintained until turbidity decreases. By 12:00 on day 53, turbidity Turbidity changed rate dropped back to 14. Reduced to approximately 1.0 NTU·h -1 Calculate the resuspension risk weighted index If the value is below the upper limit, the protection is lifted and the pulse is restored, but the parameters for the next cycle are adjusted to: pulse amplitude. The water level was lowered from 0.20m to 0.12m, and the low water level rose from 0.83m to 0.93m; the descent time... The ascent time has been extended from 6 hours to 12 hours. The low water level residence time has been extended from 5 days to 6 days. The time was shortened from 2 days to 1 day to reduce resuspension sensitivity caused by shallow water retention. Secondary wind and wave disturbances occurred on day 66 thereafter, increasing turbidity in area C. The peak value was 22, and the hourly rate of change was approximately 4 NTU·h. -1 Calculate the resuspension risk weighted index The fact that no out-of-bounds protection was triggered indicates that the floating boundary was effectively protected after parameter adjustment.

[0170] Table 5 Risk Calculation and Control Response for Typical Resuspension Events in Zone C (Day 52)

[0171]

[0172] The baseline period is consistent between the two zones (day 0: , , , , , Endogenous indicators , , As planting, consolidation, and acclimatization progressed, water quality improved in both areas. However, significant differences emerged after the strong winds and waves on day 52: In area C, due to the triggering of a protection strategy and adjustment of pulse parameters, turbidity dropped below 14 within 24 hours, and transparency recovered rapidly. Subsequent instability caused by pulse superposition and strong winds and waves did not result in prolonged turbidity. In area D, under the same wind and wave conditions, a fixed pulse was still implemented (low water level residence time was not shortened, and amplitude was not reduced), and turbidity decreased after the wind and waves. For four consecutive days, the water level remained between 20 and 26, causing a decrease in transparency and a persistently high light attenuation coefficient. This resulted in water levels in higher sections no longer meeting light compensation constraints, necessitating a passive adjustment to lower the operating water level, thus weakening algae suppression and purification efficiency. Day 55 shows the surface illumination in area D, representing the light field fit. underwater illumination profile , , , Fitting the light attenuation coefficient of water body Calculate the optical compensation depth Corresponding upper limit However, the high water level of the pulse was still close to 1.20m, which made it impossible to continue the high water level segment and forced the operation to be reversed.

[0173] This embodiment also provides comprehensive indicators of water purification operation at key time points. Comprehensive indicators of endogenous control Community recovery indicators (The construction method is the same as in Example 1, with baseline normalization and weight values ​​remaining unchanged), and the results are shown in Table 6. By day 80, region C... , , After stabilizing for two consecutive rolling cycles, the system switched to maintaining the water level. ;D zone synchronous , , The switching conditions were not met, and the operation and remedial control need to be extended.

[0174] Table 6 Comparison of water quality, endogenous source, and community indicators between the two regions at key time points (including calculation results)

[0175]

[0176] This embodiment fully demonstrates that in shallow water bodies with strong wind and wave disturbances and frequent resuspension events, after activating the resuspension risk boundary and protection strategy, the water level pulse parameters can be corrected in a timely manner without exceeding the light compensation and internal constraints, avoiding turbidity instability caused by the superposition of pulses and wind and waves, and achieving stable progress in water quality purification and submerged plant community restoration through rolling adjustment.

[0177] Example 4: Integration and operation of the control system.

[0178] This embodiment focuses on an urban regulating lake (with an effective water surface of approximately 10.8 hm²) equipped with sluice gate pumps for water regulation. 2 A closed-loop pulsed water level control system for in-situ ecological purification was constructed and put into operation to achieve stable operation of submerged plant community restoration and water purification under eutrophication conditions. The nearshore shallow water zone of the lake (approximately 1.2 hm²) 2The main purification operation area is located in a sedimentary zone consisting primarily of silt and clay, which is susceptible to short-term resuspension due to wind, waves, and scheduling disturbances. The water body is connected to an external river via a pump gate, allowing for daily water level regulation. For ease of control and calculation, the water level in this embodiment is... Defined as the water depth from the water surface to the bottom sediment surface at the representative section of the purification operation zone.

[0179] The system consists of a water level control unit, a monitoring unit, a sediment internal source control unit, and a controller. The water level control unit includes a variable frequency pump station and gate linkage mechanism, with the pump station having a maximum flow rate of 3000 m³ / h. 3 ·h -1 The gate is used for overflow regulation and safety release; the water level gauge adopts a dual-redundant deployment of pressure / radar water level sensors, with a sampling interval of 1 minute, and the water level measurement accuracy is preferably no greater than ±1 cm. The purification operation area is 1.2 hm². 2 It is estimated that the volume of water required to raise the water level by 0.10m is approximately The pumping station can complete the water adjustment within approximately 0.40 hours at the rated flow rate, thereby meeting the requirements of the pulse drop-low level stay-slow rise water level curve execution.

[0180] The monitoring unit employs a combination of online continuous monitoring and automatic sampling verification. Light field monitoring utilizes surface illumination. underwater illumination profile (Depths 0.3, 0.6, 0.9, 1.2 m) array, sampling interval 10 min; turbidity Sampling intervals were 10 minutes, and the turbidity change rate was calculated within the controller. (Obtained using 1-hour moving average and smoothed); Water quality monitoring includes chlorophyll. (30 min) and dissolved oxygen (10 min), transparency Total phosphorus was measured daily using a Seymbo disc and its consistency was checked with turbidity. The laboratory measured total phosphorus twice a week. Total nitrogen Internal source monitoring employs a combination of automated pore water sampling and in-situ measurement of overlying water: pore water sampling depth is 0–5 cm, and dissolved inorganic phosphorus in pore water is obtained on a daily scale. Water-soluble inorganic phosphorus on top Redox potential at the sediment-water interface, obtained on a daily scale. Sampling was performed every 10 minutes. Community monitoring employed an underwater camera and image processing module to achieve coverage. Identification results (once a week), combined with relative species cover to calculate community structure indices. (Every two weeks). Monitoring data is transmitted to the controller via 4G / private network. The controller uses an industrial computer to implement local caching and fault tolerance for communication interruptions: when communication is interrupted, it maintains the most recent valid water level strategy and automatically degrades the pulse amplitude to reduce risk.

[0181] The controller's operational strategy primarily follows a line of steps: determining the water level band using light compensation constraints—coordinating internal control processes—resuspending boundary constraints—parametric regulation of water level pulses—rolling tuning. For light compensation constraints, an exponential decay model is preferably used to fit the water body's light attenuation coefficient. And calculate the optical compensation depth. In order to determine the target water level zone Specifically, the controller performs least-squares fitting using profile data from four depth points: Let Then it satisfies The light attenuation coefficient of the water body is obtained by fitting the data through the origin. Light compensation depth ,Right now:

[0182]

[0183] in, To compensate for the light intensity of the target submerged plant. In this embodiment, Vallisneria natans is selected as the dominant species and... As compensation for light intensity, the target canopy height is taken as... Safety margin Calculate the upper limit based on this. The lower limit was determined by combining shallow thermal stress and operational safety. The results of light field fitting and constraint calculations for day 0 of the baseline period and day 50 of the strong wind and wave period are shown in Table 7: Water light attenuation coefficient during the baseline period. Light compensation depth Upper limit When strong winds and waves exacerbate water turbidity, the light attenuation coefficient of the water body... Increase to Light compensation depth Down to Upper limit convergence to Based on this, the controller automatically tightens the upper limit constraint of the water level during periods of wind and waves, and limits or suspends the high-level segment of the pulse high water level to ensure that the water level curve always meets the light compensation constraint.

[0184] Table 7. Light field fitting and upper limit calculation of target water level zone at key time points

[0185]

[0186] Regarding resuspension and intrinsic constraints, the controller uses a risk-weighted index plus an allowable upper limit for online boundary determination and links it with the protection strategy. For ease of implementation, this embodiment employs baseline normalization. ,in The baseline mean for days 0-6 (baseline in this example: , , , , , , , , ), turbidity change rate This indicates that a scale constant is taken. Resuspension risk weighted index The following formula is used for calculation, and an upper limit is set. At the same time, a direct threshold for the rate of change is set. ,Right now:

[0187]

[0188]

[0189] Endogenous release risk-weighted index The following formula is used for calculation, and a trigger threshold is set. Allowable upper limit .Right now:

[0190]

[0191] Comprehensive indicators of water purification operation Comprehensive indicators of endogenous control They are respectively:

[0192]

[0193]

[0194] in, , As a criterion for phase transition. Community recovery index. By coverage Community structure index The target coverage is obtained by weighting after normalization. Target diversity (Weight 0.6 / 0.4), and set the indicator threshold. The above formula is used in this embodiment to improve the verifiability and feasibility of the controller. In actual engineering, the threshold and weight can also be adjusted according to the water type and target requirements.

[0195] Regarding the execution of water level pulses, the controller uses... For the controlled object, water level pulse From parameter set Definition. After completing the low-water-level planting window and gradual rise acclimatization in the initial stage of system operation, a benchmark operating water level is selected. And set the initial pulse parameters. , , , , , When a resuspension risk-weighted index appears... Out of bounds or turbidity change rate When the limit is exceeded, the controller preferably executes a pause pulse and enters a protective steady-state water level strategy, while updating the pulse parameters for the next cycle according to the degradation rule (e.g., lowering the level). ,extend and ,shorten ), and with a real-time updated upper limit Constraints on high water levels are checked to prevent light compensation defaults caused by blindly raising water levels to reduce resuspension during turbid periods. For endogenous risks, risk-weighted indicators are used when endogenous risks are released. Continuous occurrence and endogenous control comprehensive indicators During synchronous rise, the controller, in conjunction with the sediment internal source control unit, executes the replenishment and consolidation window, and during the consolidation period, reduces the water level change rate limit to the consolidation limit. Pulses can be paused or limited to reduce the risk of resuspension and diffusion.

[0196] The sediment endogenous control unit is implemented at the system level using a "metered slurry preparation—quantitative addition—uniform distribution" method. It includes a 10m... 3 For the slurry tank, agitator, metering pump, and dispensing pipeline / dispensing device, the solid material dosing accuracy is preferably no less than ±3%. When the controller triggers an endogenous risk response, it is preferable to implement thin-layer supplementary dosing within the risk hotspot grid. In this embodiment, an increase in endogenous risk occurred on day 58 (see Table 8), and the system was adjusted according to the hotspot area. Supplementary dosage shall be added, and the dosage shall be based on... If we set the total mass of the solid material, then... for:

[0197]

[0198] The pulp concentration is 10 wt%, which corresponds to a pulp volume of approximately (Based on density approximation) ), metering pump flow rate The dispensing time is approximately After the supplementary addition is completed, the system will automatically enter the consolidation period. Furthermore, the limits for pulse amplitude and water level change rate were lowered, and a final review was conducted at the end of the consolidation period. , and To determine whether the consolidation state has been lifted.

[0199] During system operation, the controller updates the resuspending risk weighted index every 10 minutes. Weighted index of endogenous release risk It also performs boundary crossing detection and updates the water body light attenuation coefficient daily based on light field data. Light compensation depth With the target water level zone The rolling tuning result is output and the pulse parameters are updated every 7 days; when , , Continuously satisfy no less than During each rolling cycle, the system automatically switches to maintaining the water level. Then the pulse stops, and the purification maintenance phase begins.

[0200] Table 8 lists the monitoring data, index calculations, and system actions at key time points in this embodiment. A strong wind and wave resuspension event occurred on day 50, with measured turbidity... Turbidity change rate Calculate the resuspension risk weighted index Protection is triggered; the controller immediately suspends the current pulse and maintains the water level at the protected steady-state level. And downgrade the pulse parameters for the next cycle to , , , Ensure that the upper limit obtained from Table 7 is met during this period. Under constraints, the high water level pulse did not exceed the limit. An increase in endogenous risk occurred on day 58; the endogenous release risk-weighted index was calculated. And endogenous control comprehensive indicators A significant increase was observed, triggering the system to initiate supplementary injection and consolidation phases; post-consolidation review indicators showed... , , The switching conditions are met and the system enters the maintenance phase.

[0201] Table 8 Key Time Point Monitoring Data, Indicator Calculation, and System Action Log

[0202]

[0203] As can be seen from this embodiment: Firstly, the controller is based on the water light attenuation coefficient obtained by real-time light field fitting. With light compensation depth The system dynamically determines the target water level zone and constrains pulsed high and low water levels, ensuring that water level operation is always constrained by the light compensation boundary; secondly, the controller uses a resuspension risk-weighted index. Weighted index of endogenous release risk The online discrimination constitutes a dual risk boundary between resuspension and endogenous release, and the protection strategy realizes automatic degradation of pulse parameters and steady-state water level switching to avoid turbidity instability caused by wind and wave superposition pulses; thirdly, the sediment endogenous control unit is coupled with water level operation in a coordinated manner through hot spot identification, quantitative replenishment and consolidation window, and controls resuspension and diffusion through the water level change rate limit during the consolidation period, so that the system can stably reach the stage switching conditions of purification and recovery under engineering conditions and enter the maintenance operation.

[0204] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0205] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Since the above embodiments are substantially similar to the method embodiments, their descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0206] The above embodiments provide a detailed description of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for restoring submerged communities using a closed-loop pulsed water level system with dual constraints of light compensation and resuspension, characterized in that... The method includes the following steps: S1. Collect water samples from the area to be purified, including water level. ,transparency turbidity Surface illumination and underwater illumination profile The water environment parameters are obtained, at least one water quality purification characterization parameter and an endogenous pollution characterization parameter are obtained, and a set of purification control target thresholds and an endogenous control threshold set are set. The water quality purification characterization parameters include at least chlorophyll. Total phosphorus Total nitrogen Dissolved oxygen One or a combination thereof; The endogenous pollution characterization parameters include at least dissolved inorganic phosphorus in the overlying water. Dissolved inorganic phosphorus in sediment pore water Redox potential at the sediment-water interface One or a combination thereof; S2. Calculations based on water environment parameters are used to determine the target water level zone. Light compensation depth And select the planting window water level for different stages of water level operation. , benchmark operating water level Maintaining water level ,include: Fitting with an exponential decay model or transparency Empirical conversion estimation of water body light attenuation coefficient ,Right now: The light attenuation coefficient of water body was obtained by fitting an exponential decay model. for: ； in, Indicates the depth of underwater illumination; Use transparency Empirical conversion estimation of water body light attenuation coefficient for: ； in, This is an empirical coefficient; Based on the light attenuation coefficient of water body Calculate the optical compensation depth The calculation formula is: ； in, Compensating light intensity for target submerged plants; Based on the light compensation depth Target canopy height and safety margin Determine the target water level zone ,Right now: upper limit Meet the target canopy height from the water surface The optical path distance at the top is no greater than Among them, safety margin Desirable Lower limit Determined by considering shallow water stress, operational safety, and engineering boundary conditions; In the target water level zone Within the range, the planting window water level is selected for different stages of water level operation. , benchmark operating water level Maintaining water level ; S3. For the water area to be purified, the following steps are performed in sequence: setting a low-water-level planting window, controlling the endogenous sources of sediment, and a gradual acclimatization stage. The water environment parameters are dynamically updated to adjust the target water level zone. ,include: The low-water-level planting window setting includes: setting the water level as the planting window level. Maintaining the duration of the planting window under the following conditions A low-water-level planting window is set up to complete the release, establishment, or fixation of submerged plant seed sources and propagules, and turbidity is used as a constraint. As a constraint for purification operation during the planting period; The sediment endogenous control process includes: laying and / or adding sediment blocking materials and / or sediment stabilizing materials before or during the subsequent gradual rise acclimatization stage or water level pulse stage, and setting a consolidation time. During the consolidation time The rate of change of internal water level shall not exceed the consolidation limit. To reduce the risks of resuspension and endogenous release; The gradual acclimatization phase includes: raising the water level from the planting window level. Adjust to the baseline operating water level During the adjustment process, the rate of water level change must not exceed the acclimatization limit. And includes at least one steady-state holding phase. At the end of each steady-state holding segment, based on the updated transparency and underwater illumination profile Recalculate optical compensation depth and the target water level zone Compared with the benchmark operating water level Make adjustments to maintain the submerged plant canopy in compliance with light compensation constraints; S4. Construct the purification operation boundary of the water level pulse stage, including the resuspension risk weighted index and the endogenous release risk weighted index, and determine whether the water level pulse stage has been entered. When water quality purification characterization parameters deviate from the set of purification control target thresholds and / or algae risk increases, at the baseline operating water level... Superimposed water level pulse Forming a water level curve And the water level always meets The light compensation constraint is used, and the boundary constraint and protection are carried out by the resuspension risk weighting index and the endogenous release risk weighting index. S5. Construct a comprehensive index for water body purification operation. Comprehensive indicators of endogenous control , with rolling cycle Set the pulse parameters for the water level pulse phase and switch the water level to the maintenance level. Entering the purification and maintenance phase enables full-cycle operation control.

2. The water level pulse closed-loop submerged community restoration method according to claim 1, characterized in that, Also includes: When the endogenous pollution characterization parameters or phosphorus diffusion flux are mentioned If the set of endogenous control thresholds is not met, perform supplementary substrate blocking / stabilization procedures or extend the consolidation time. And temporarily postpone entering the water level pulse phase; The phosphorus diffusion flux Using an approximate calculation, the expression is: ； in, The equivalent diffusion coefficient; The thickness is the diffusion boundary layer.

3. The water level pulse closed-loop submerged community restoration method according to claim 1, characterized in that, The substrate blocking material includes a phosphorus control coating material, an isolation layer material, or a composite structure thereof; The substrate stabilizing material includes solidification stabilizing materials, flocculation-consolidation materials, or combinations thereof; and the consolidation time is... Water level change rate limit during the period Less than the domestication limit .

4. The water level pulse closed-loop submerged community restoration method according to claim 1, characterized in that, Step S4 includes: Based on online monitoring of turbidity With turbidity change rate Normalized weighted resuspension risk-weighted index And set the allowed upper limit, the expression is: ； ； in, Indicates the turbidity after normalization; This represents the rate of change in turbidity after normalization. All are weighting coefficients, and ; Based on the dissolved inorganic phosphorus in the overlying water Dissolved inorganic phosphorus in sediment pore water Redox potential at the sediment-water interface Normalized weighted index for constructing endogenous risk release And set the allowed upper limit, the expression is: ； in, This indicates the dissolved inorganic phosphorus in the overlying water after normalization; This represents the difference between dissolved inorganic phosphorus in sediment pore water and dissolved inorganic phosphorus in overlying water after normalization. This represents the normalized redox potential of the sediment-water interface; All are weighting coefficients, and ; When resuspension risk weighting indicators Or endogenous release risk weighted index When it reaches its allowable upper limit, or the rate of change of turbidity Exceeding the threshold When the protection policy is activated; The protection strategy includes at least limiting the rate of water level change, reducing the amplitude of water level pulses, extending the pulse rise / fall process, extending the low water level residence time, pausing water level pulses, and restoring the water level to the reference operating level. And to implement or strengthen the control of endogenous sources in sediment.

5. The water level pulse closed-loop method for restoring submerged communities according to claim 1, characterized in that, Step S4 includes: Throughout the entire water level pulse phase, the resuspension risk-weighted index Weighted index of endogenous release risk All are below their allowable upper limit in order to suppress disturbance to algae / attached biofilms, reduce shading and promote increased transparency; The water level curve The expression is: ； In the formula, Baseline operating water level Water level pulse From parameter set The definitions correspond to pulse amplitude, respectively. ,cycle Ascent time descent time High water level residence time and low water level residence time Pulse parameters; The water level pulse An asymmetric waveform is used, and the rise time is satisfied. With descent time The ratio is not greater than or not less than And pulse amplitude for ,cycle for Low water level residence time Occupying the period of .

6. The water level pulse closed-loop method for restoring submerged communities according to claim 5, characterized in that, Step S5 includes: With rolling cycle Obtain the coverage of submerged plants Community structure index Water quality purification characterization parameters and endogenous pollution characterization parameters are used to construct a comprehensive index for water body purification operation. Comprehensive indicators of endogenous control ; Comprehensive indicators of water purification operation The expression is: ； in, Indicates the normalized transparency; This represents the normalized dissolved oxygen. This represents the normalized chlorophyll content; , This represents the normalized total phosphorus and total nitrogen; These are the weighting coefficients, and ; Endogenous control comprehensive index The expression is: ； in, This indicates the dissolved inorganic phosphorus in the overlying water after normalization; This represents the difference between dissolved inorganic phosphorus in sediment pore water and dissolved inorganic phosphorus in overlying water after normalization. Indicates the turbidity after normalization; These are the weighting coefficients, and ; Comprehensive indicators of water purification operation The primary goal is to improve [the quality of], with endogenous control comprehensive indicators as the main focus. The improvement is the constraint target, while satisfying the optical compensation constraint. Resuspension constraints With internal constraints Under the condition of the parameter set Compared with the benchmark operating water level Perform rolling adjustment; , These are the comprehensive indicators of water purification operation. Comprehensive indicators of endogenous control The maximum allowed limit; When the comprehensive indicators of water purification operation Achieving the set of purification target thresholds and the comprehensive indicators of endogenous control Reaching the set of intrinsic control target thresholds and continuously satisfying no less than [a certain number of] [thresholds]. One rolling cycle When the water level pulse stops, the controller switches the water level to the maintenance level. Entering the purification and maintenance phase.

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