A method and system for pulse ecological regulation of dam water bloom prevention and control

Abstract

The application discloses a kind of gate dam water bloom prevention and control pulse ecological regulation method and system, belong to water conservancy ecological protection technical field.The method includes: identification gate dam front control river section and layout monitoring point position;Collect multi-source monitoring data;Build comprehensive water bloom risk index HRI covering algal biomass, growth trend, hydrodynamic condition, environmental suitability and nutrient salt supply, according to which water bloom risk is divided into four grades;Match corresponding intensity pulse regulation sequence, generate executable scheme after multiple engineering safety constraint check;According to the rule of slow rise-maintenance-slow decline, execute gate regulation;After scheduling is completed, evaluate effect and adaptively correct risk index parameter and regulation sequence parameter.The application realizes the change of gate dam operation from passive flow preservation to active prevention and control type ecological regulation, with the advantages of accurate comprehensive risk identification, effective algal inhibition of hierarchical disturbance, comprehensive safety constraint and closed-loop feedback optimization.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and ecological protection technology, and in particular to a pulsed ecological scheduling method and system for preventing algal blooms at dams and sluices. Background Technology

[0002] Dam-type rivers, small reservoirs, and urban landscape water retention bodies play a vital role in flood control, water supply, irrigation, landscape maintenance, and ecological water replenishment. However, dam construction alters the continuous flow of natural rivers, transforming the river section in front of the dam from a relatively open flowing water body into a slow-flowing, backwater, or near-still water body. This generally results in reduced flow velocity, prolonged hydraulic residence time, weakened vertical exchange, increased retention zones along the banks, and accumulation of nitrogen and phosphorus nutrients. Under conditions of rising water temperature, ample sunlight, and low water inflow, these water bodies are highly susceptible to abnormal proliferation of phytoplankton such as cyanobacteria and green algae, leading to algal blooms, causing the water to turn green, develop an unpleasant odor, experience fluctuations in dissolved oxygen, and decline in aquatic ecological functions.

[0003] In actual management, algal blooms in front of dams are usually sudden and localized. On the one hand, algal growth is affected by water temperature, light, nutrients, and water retention time, and a single water quality indicator is difficult to reflect changes in risk in a timely manner. On the other hand, although the stable water storage and fixed discharge flow of dams are beneficial to water supply or landscape maintenance, they may also cause the formation of a stable light layer and surface algal bloom zone in the slow-flowing area in front of the dam, accelerating the formation of algal blooms.

[0004] Current dam and sluice gate operations primarily focus on flood control, water level control, water supply security, irrigation water intake, or ecological baseflow discharge, neglecting the needs of algal growth and hydrodynamic disturbances. This results in several significant shortcomings: First, the operational objectives are too singular, rarely incorporating chlorophyll a concentration, algal growth rate, or water retention time as direct targets, making proactive control of abnormal algal proliferation in front of the dam difficult. Second, triggering conditions are empirically based, often relying on single water quality indicators as early warning for algal blooms, lacking multi-factor comprehensive risk assessment methods, leading to delayed responses or false triggers. Third, operational actions lack parameterization. The design of algae suppression measures such as short-term pulse discharge and water level fluctuation lacks a unified design for flow rate, duration, and frequency, making it difficult to replicate and promote. Fourth, engineering constraints are not adequately considered; simply increasing the discharge to suppress algae may cause a sudden drop in the water level in front of the dam, a sudden change in the water level downstream, impact on water intake, or risks to the operation of gate equipment. Fifth, the feedback correction mechanism is incomplete, relying heavily on manual experience or one-time calculations, lacking a parameter correction mechanism based on actual measurement results, making it difficult to adapt to different dams and hydrological conditions. Sixth, some control measures rely on engineering modifications such as aeration, chemical dosing, and dredging, resulting in high investment and maintenance costs, and are not suitable for a large number of existing small dams.

[0005] Therefore, there is an urgent need to develop a dam ecological scheduling method that does not require large-scale modification, can proactively identify algal bloom risks, implement tiered pulse disturbances, and simultaneously take into account engineering safety. Summary of the Invention

[0006] The purpose of this invention is to provide a pulsed ecological scheduling method for controlling algal blooms in dams. This method mainly achieves algal control in front of dams by optimizing monitoring data, calculation rules, and gate operation modes. It is applicable to dam-type rivers, water areas in front of small reservoir dams, and urban impounded water bodies with certain gate regulation capabilities.

[0007] To achieve the above objectives, this invention provides a pulsed ecological scheduling method for controlling algal blooms at dams and sluices, comprising the following steps: S1. Identification of Controlled River Sections and Delineation of Monitoring Units: Conduct engineering surveys of the river sections in front of dams and gates within the target watershed, determine the spatial boundaries of the controlled river sections, calculate the volume V of the controlled water body, and set up monitoring sections and sampling points. S2. Multi-source data acquisition and preprocessing: Acquire dam engineering and operation data, hydrological and hydrodynamic data, water quality and algae data, meteorological and light data, and perform data quality control and unified processing; S3. Construction of Algal Bloom Risk Index and Risk Level Determination: Calculate the chlorophyll a concentration risk factor SC, growth rate risk factor Sr, hydraulic retention risk factor STres, water temperature suitability ST, light suitability SI, nutrient salt risk factor SNP, and flow insufficiency Sv to construct a comprehensive algal bloom risk index HRI. Based on the HRI value, algal bloom risk is divided into four levels: Level I low risk, Level II concern risk, Level III early warning risk, and Level IV scheduling risk. S4. Dispatch Period Identification: Identify five types of dispatch periods: low water retention period, normal water maintenance period, high water flushing period, high algal bloom period, and special sensitive period, as scenario constraints for dispatch scheme generation; S5. Generation of ecological gate scheduling scheme: Combine the risk level of algal bloom with the type of scheduling period to generate candidate gate action sequences of corresponding intensity. Then, based on the constraints of ecological base flow, maximum safe discharge, upstream water level, downstream water level fluctuation, gate opening and closing rate, and dual constraints of scheduling water exchange and reservoir capacity consumption, safety verification and screening are carried out to output an executable gate scheduling scheme. S6. Real-time monitoring and early warning and gate scheduling execution: Real-time access to online monitoring data and gate operation data, execute gate operations according to the scheduling plan, and immediately handle abnormal operating conditions; S7. Scheduling effect evaluation and adaptive parameter correction: Calculate the chlorophyll a reduction rate, growth rate inhibition rate, actual water exchange ratio, unit water exchange reduction efficiency, and downstream water level change rate constraint indicators, and adaptively correct the scheduling sequence parameters, HRI weight, and trigger threshold based on the evaluation results.

[0008] Preferably, the formula for calculating the Comprehensive Algal Bloom Risk Index (HRI) in step S3 is as follows:

[0009] The formulas for calculating each risk factor are as follows:

[0010]

[0011]

[0012]

[0013]

[0014]

[0015] In the formula, The comprehensive algal bloom risk index at time t, with a value ranging from 0 to 1; , , , , , and The weights of each risk factor are 1, and the sum of the weights is 1. Let be the chlorophyll a concentration at time t; and These are the low-risk threshold and the high-risk threshold, respectively. This represents the logarithmic growth rate of chlorophyll a. To avoid tiny positive numbers that are zero when their logarithm is taken; This represents a high-growth risk threshold. The hydraulic residence time; The critical residence time at which algal accumulation is likely to occur; Let t be the water temperature. The optimal temperature; This is the temperature response width parameter; and These are the total nitrogen and total phosphorus concentrations, respectively. and This is a reference threshold.

[0016] Preferably, the risk level determination rule in step S3 is: Level I Low Risk: HRI < 0.25, algae levels are low and there is no upward trend; Level II Risk Concern: 0.25≤HRI<0.50, conditions for algal growth are present but no significant aggregation has yet occurred; Level III warning risk: 0.50≤HRI<0.75, or Chla rises for 3 consecutive days with a cumulative increase of more than 10%-20%, indicating rapid algal growth or significant water stagnation; Level IV scheduling risk: HRI≥0.75, or Chla exceeds the control threshold and lasts for 2-3 days, indicating a high probability of algal bloom or local clustering. If the HRI calculation level is inconsistent with the on-site inspection results, the principle of strict risk management shall be followed, and the response measures shall be implemented according to the higher risk level.

[0017] Preferably, in step S4, the scheduling time periods are divided into five categories: During the dry season, the inflow rate is lower than the 25th percentile of the same period over many years and the hydraulic retention time exceeds the critical value, resulting in weak water body renewal capacity. During the period of water level maintenance, the inflow is at the 25th to 75th percentile of the same period over many years and the risk is at level I to II, and the hydrological conditions are stable. During the high-water flushing period, if the inflow is higher than the 75th percentile of the same period in previous years or if significant rainfall runoff is forecast, natural water can be used to assist in water exchange. During the peak period of algal blooms, when the water temperature is above 15℃ for more than two consecutive days, the light is suitable, and the risk level reaches Level II or above, the algal proliferation rate is rapid. During particularly sensitive periods, when there are water intakes, ecologically sensitive targets, or water-related construction downstream, the intensity and rate of scheduling disturbances must be strictly limited.

[0018] Preferably, the candidate gate action sequence in step S5 includes: Level I low risk corresponds to the normal ecological base flow sequence, maintaining the outflow rate at no less than the ecological base flow, maintaining stable operation during the normal and dry seasons, and coordinating with natural water inflow during the wet season; Level II risk corresponds to the underlying micro-disturbance sequence. Short-term gate fine-tuning is carried out 1-2 times daily, with each adjustment lasting 15-30 minutes. The disturbance flow is 1.1-1.5 times the ecological base flow. The lower limit parameter is used during special sensitive periods. Level III early warning risk corresponds to a small-pulse water exchange sequence, which adopts a slow rise-maintenance-slow fall opening and closing method. The flow rate of a single pulse is 1.5 to 2.5 times the ecological base flow, and the duration of a single pulse is 0.5 to 2 hours. The target water exchange ratio is 0.10 to 0.25. Level IV scheduling risk corresponds to a combination sequence of pulsed discharge and water level fluctuations. The pulsed flow rate is 2.0 to 4.0 times the ecological base flow, the target water exchange ratio is 0.25 to 0.50, and it is coordinated with water level periodic fluctuations of 0.10 to 0.50m. During the high-water season, natural runoff is used to achieve this.

[0019] Preferably, the safety constraints in step S5 include the following six items: Ecological baseflow constraint: The outflow rate at any time period shall not be lower than the ecological baseflow; Maximum safe discharge constraint: The discharge flow at any time shall not exceed the smaller value between the dam's safe discharge flow and the downstream maximum allowable flow. Dam inlet water level constraint: During the scheduling process, the dam inlet water level is between the minimum control water level and the maximum allowable water level; Downstream water level fluctuation constraint: The rate of change of downstream water level shall not exceed the maximum allowable value; Gate opening and closing rate constraint: The rate of change of gate opening shall not exceed the upper limit of the hoist's allowable limit; Water storage capacity constraint: The net water consumption in front of the dam during the scheduling period shall not exceed the adjustable water storage capacity.

[0020] Preferably, the gate scheduling execution in step S6 is divided into three stages: Gradual rise phase: Gradually raise the gate to the target opening, monitor the downstream water level in real time, and suspend further opening if the water level rise exceeds the warning value; Maintenance phase: Maintain the target discharge flow rate to the design duration, focusing on monitoring changes in discharge flow rate, upstream water level, chlorophyll a concentration, and flow velocity; Gradual descent phase: After the design duration is reached, the opening is gradually restored to the basic opening. If any abnormal conditions occur during the operation, such as a sudden rise in downstream water level, gate malfunction, or sudden drop in dissolved oxygen, the operation should be immediately suspended, the target flow rate reduced, or the scheduling terminated early.

[0021] Preferably, the scheduling effect grading evaluation standard in step S7 is as follows: Effective: Chla decreases within 24-48 hours, HRI decreases by at least one level, algal aggregation in the field weakens, no safety anomalies are observed, and the current sequence parameters are retained as the preferred calling scheme; Partially effective: If Chla or HRI decreases but does not reach the target, or if algae show a short-term rebound, appropriately increase the pulse duration, frequency, or water level fluctuation amplitude; Invalid: Chla continued to rise, HRI did not decrease, algal aggregation at the site worsened, risk level increased and sequence type adjusted; Not suitable for execution: When there is abnormal downstream water level, water supply risk or equipment malfunction, the pulse intensity should be reduced, the scheduling duration should be shortened, the applicable conditions of this type of sequence should be restricted, and this type of scheduling sequence should be stopped if necessary.

[0022] Preferably, the adaptive parameter correction in step S7 includes: The scheduling sequence parameters are corrected using the exponential smoothing method as follows:

[0023] In the formula, P new The corrected scheduling parameters; P old The original scheduling parameters; P obs The appropriate parameters are derived by working backward from the scheduling results. The update coefficient is set to 0.1-0.3; P represents the pulse flow rate Q. pulsePulse duration t pulse Water level fluctuation range dH or target water exchange ratio R target ; HRI weights are adjusted using the following formula:

[0024] In the formula, The new weights are adjusted for the i-th risk factor; The original weight of the i-th risk factor; The importance of the i-th risk factor in the determination of algal bloom occurrence; It is the sum of the importance of all risk factors; Let i be the normalized importance of the i-th risk factor; Update the coefficients for the weights.

[0025] A pulsed ecological scheduling system for controlling algal blooms at dams, used to implement the method described above, includes: The data acquisition module is used to collect dam engineering and operation data, hydrological and hydrodynamic data, water quality and algae data, and meteorological and light data. The Algal Bloom Risk Index Calculation Module is used to calculate the chlorophyll a concentration risk factor SC, growth rate risk factor Sr, hydraulic retention risk factor STres, water temperature suitability ST, light suitability SI, nutrient salt risk factor SNP, and flow insufficiency Sv to construct a comprehensive Algal Bloom Risk Index HRI. Based on the HRI value, the Algal Bloom risk is divided into four levels: Level I low risk, Level II risk of concern, Level III early warning risk, and Level IV scheduling risk. The scheduling period identification module is used to identify the dry water retention period, the normal water maintenance period, the wet water flushing period, the high algal bloom period, and special sensitive periods; The scheduling scheme generation module is used to generate candidate gate action sequences by matching the algal bloom risk level with the scheduling period type. It also performs safety checks and screening based on ecological base flow constraints, maximum safe discharge constraints, upstream dam water level constraints, downstream water level fluctuation constraints, gate opening and closing rate constraints, and reservoir capacity consumption constraints, and outputs an executable gate scheduling scheme. The gate control execution module is used to control the gate action according to the scheduling plan and monitor the water level, flow rate and equipment status in real time. The effect evaluation and parameter correction module is used to calculate scheduling effect indicators and adaptively correct scheduling sequence parameters, HRI weights and trigger thresholds. The early warning and anomaly handling module is used to generate early warning information when the HRI reaches level II or above, and to perform pause, flow reduction or early termination operations when abnormal operating conditions occur.

[0026] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: 1. Precise and forward-looking identification of algal bloom risks A comprehensive algal bloom risk index is constructed, encompassing multiple dimensions such as algal concentration, growth rate, hydraulic retention, water temperature, light intensity, nutrients, and flow velocity. This index overcomes the limitations of judging algal blooms using a single water quality indicator, enabling early detection of algal proliferation trends, effectively reducing misjudgment rates and response delays, and achieving graded early warning and proactive identification of algal bloom risks.

[0027] 2. Pulse scheduling standards are replicable. The scheduling sequences, including bottom-level micro-disturbance, small-pulse water exchange, and combined pulse water discharge, are designed according to risk level gradients. The pulse flow rate, duration, gate opening and closing process, execution frequency, and stopping conditions are uniformly parameterized, eliminating reliance on manual experience and enabling rapid replication and promotion to different types and scales of dam and gate projects.

[0028] 3. Coordination between ecological prevention and control and engineering safety During the scheduling scheme generation phase, six safety constraints are simultaneously coupled: ecological base flow, maximum safe discharge, upstream water level, downstream water level fluctuation, gate opening and closing rate, and adjustable storage capacity. This ensures the effectiveness of algal disturbance and algal bloom control while avoiding operational risks such as sudden drops in upstream water level, downstream river scouring, water supply interruption, and gate equipment overload.

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart illustrating the overall process of a pulsed ecological scheduling method for controlling algal blooms at dams according to Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the sampling section and sampling point layout in the river section in front of the dam in Embodiment 1 of the present invention; Figure 3 A logical diagram for constructing the risk-level gate ecological scheduling sequence library of Embodiment 1 of the present invention; Figure 4 This is a diagram illustrating the safety and executability constraints of the pulse disturbance scheduling scheme in Embodiment 1 of the present invention. Figure 5 This is a closed-loop diagram of real-time monitoring, gate scheduling execution, effect evaluation, and parameter adaptive correction in Embodiment 1 of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] 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.

[0034] Example 1 like Figure 1 As shown, the implementation process and application effect of this method will be specifically explained through the following examples, combined with the actual scheduling scenarios of typical dams.

[0035] S1. Delineation of Controlled River Section Identification and Monitoring Units Select river sections upstream of dams that meet the requirements for algal bloom control, clarify the spatial boundaries of the controlled river sections, deploy tiered monitoring sections and sampling points, and calculate the volume of the controlled water body to provide a spatial benchmark for subsequent algal bloom risk calculation and scheduling parameter setting. The specific steps are as follows: S1.1 Target Audience Filtering S1.1.1 Conduct an engineering survey of the river sections upstream of dams, rubber dams, weirs, and small reservoir dams within the target watershed to obtain information such as dam name, location, dam height, number of gate openings, gate size, normal water level, dead water level, dispatching and management unit, and operation mode. Data sources should primarily be the water administration department, dam operation and management unit, engineering design data, or as-built documentation; when data is lacking, supplementary data should be obtained through on-site reconnaissance and RTK (Real-Time Kinematic) real-time dynamic measurement technology.

[0036] S1.1.2 River sections that meet any of the following conditions will be listed as candidate control river sections: the water surface in front of the dam is significantly widened; the normal flow velocity is less than 0.05-0.10 m / s; the water retention time during the dry season or normal season exceeds 2 days; algal blooms, algal aggregation, chlorophyll a increase or greening of the water have occurred in the past 3 years; there are nutrient sources such as tributary inflow, domestic sewage or agricultural runoff in front of the dam.

[0037] S1.1.3 If there are multiple candidate dams in the same basin, they shall be prioritized according to four indicators: frequency of algal bloom, degree of retention in front of the dam, downstream sensitive targets, and controllability of scheduling. The river section with high risk of algal bloom and gate regulation capacity shall be selected as the implementation target.

[0038] S1.2 Control Boundary Delineation S1.2.1 Upper Boundary Determination: The upper boundary of the control section is determined by the upper limit of the backwater influence corresponding to the normal water level of the dam. When backwater line data is lacking, it can be determined by on-site water surface slope, abrupt changes in flow velocity, or by interpretation of UAV imagery. Generally, the location where the flow velocity changes from a natural river state to a slow flow state is taken as the upper boundary.

[0039] S1.2.2 Determination of the lower boundary: The lower boundary of the control section shall be the axis of the dam or the cross-section 10-50 m upstream of the dam. If there is a significant algal accumulation area upstream of the dam, the entire accumulation area shall be included in the control section.

[0040] S1.2.3 Determination of lateral boundaries: The waterline of the left and right banks under normal water level conditions shall be used as the boundary, and the backflow bay, stagnant water area, discharge outlet mixing area and dense aquatic plant zone shall be used as key densification units.

[0041] S1.2.4 Calculation of Controlled Water Volume: Calculate the water volume V of the controlled river section based on measured cross-sections or reservoir capacity-water level curves. If the cross-section method is used, divide the controlled river section into m-1 calculation units, summing the average area of ​​adjacent cross-sections by the cross-section spacing, and calculate using the following formula:

[0042] In the formula, To control the water volume of a river section, the unit is m. 3 ; and The water flow area of ​​adjacent cross sections, in meters. 2 ; This represents the distance between adjacent cross sections, in meters (m); m represents the number of cross sections. This volume is used for subsequent calculations of hydraulic retention time, water exchange ratio, and pulse duration.

[0043] S1.3 Monitoring Section and Sampling Point Layout S1.3.1 Longitudinal Cross-Section Layout: At least five types of cross-sections shall be set up in the controlled river section, namely S0 inflow control cross-section, S1 backwater starting point cross-section, S2 mid-section retention cross-section, S3 algae accumulation or bank retention cross-section, and S4 main control cross-section upstream of the sluice gate. If the length of the controlled river section is less than 300 m, it can be compressed into three cross-sections: S0, S2, and S4; if the length is greater than 1000 m, an intermediate cross-section shall be added every 300-500 m.

[0044] S1.3.2 Lateral sampling point layout: When the river width is less than 20 m, one sampling point is set up along the main flow line in each cross section; when the river width is 20-50 m, three sampling points are set up on the left, middle and right sides; when the river width is greater than 50 m or there is a clear bank retention zone, one to two additional sampling points are set up along the bank where algae accumulate, in addition to the existing left, middle and right sampling points.

[0045] S1.3.3 Vertical Stratification: When the water depth is less than 1.5 m, collect water samples from the surface layer (0.3-0.5 m) and near the bottom layer (0.3-0.5 m from the bottom); when the water depth is 1.5-5 m, collect water samples from the surface, middle, and near-bottom layers; when the water depth is greater than 5 m and there is a risk of stratification, deploy a profile monitoring layer every 1-2 m. Online sensors are preferentially deployed at the surface layer (0.5 m), and near-bottom flow velocity monitoring is added at the main control section upstream of the gate.

[0046] S1.3.4 Fixed monitoring point numbering: The numbering method is "section number - lateral position - vertical stratum". For example, S4-MU represents the surface point at the center line of the main control section in front of the dam, and S3-LB represents the near-bottom point on the left bank of the algae accumulation section. The latitude and longitude, water depth, distance from the dam and corresponding function of all points should be recorded.

[0047] S1.3.5 Output results: as follows Figure 2 As shown, a control river section boundary map, a monitoring section layout map, a sampling point table, and a control water volume table are generated, which serve as the basis for subsequent data collection and scheduling calculations.

[0048] S2 Multi-source Data Acquisition and Preprocessing This step is used to establish the basic dataset required for the ecological scheduling of dams and sluices. Data types include five categories: dam and sluice engineering and operational data, hydrological and hydrodynamic data, water quality and algae data, meteorological and solar data, and auxiliary survey data on external inputs and shoreline retention. The principles for surface water monitoring site selection, sampling, quality control, and data processing can be followed in accordance with current surface water environmental quality monitoring technical specifications, water quality sampling technical guidelines, and surface water environmental quality standards. Specific steps are as follows: S2.1 Dam and Gate Engineering and Operation Data S2.1.1 Data Acquisition: Collect engineering design data, as-built data, scheduling procedures, historical gate opening and closing records, water level records, and discharge curves from the dam operation and management unit. Obtain at least the daily operation data for the past 3 years; if automated recording is available, hourly or higher frequency data on gate opening, water level, and discharge flow should also be obtained.

[0049] S2.1.2 On-site verification: On-site verification shall be conducted on the number of gates, single-hole width, gate bottom elevation, hoist type, maximum opening degree, minimum controllable opening degree, opening and closing speed, and upstream water gauge. If the historical discharge curve is incomplete, the measured flow rate shall be selected under a typical opening degree for verification.

[0050] S2.1.3 Establishing the gate discharge relationship: Establish the correspondence between gate opening G, head difference H, and discharge flow rate Qout. If a calibration curve already exists, use it directly; if no calibration curve exists, an empirical formula can be used for preliminary estimation, and then corrected through on-site flow rate testing. The calculation formula is as follows:

[0051] In the formula, The flow rate is for a single outlet or the total discharge flow, in m³ / s. denoted as _ ...

[0052] S2.1.4 Data Preprocessing: Unify gate opening, water level, and flow rate to an hourly scale. For data with missing periods of less than 3 hours, use linear interpolation between adjacent time periods; when missing periods exceed 3 hours or when abnormal operating conditions such as gate maintenance or power outages occur, these should be marked as abnormal operating periods and not used for key parameter verification.

[0053] S2.2 Hydrological and hydrodynamic data (1) Inflow data acquisition: The inflow flow rate Q is acquired at section S0. in The flow rate can be calculated using hydrological station data, upstream inflow records of dams and gates, ADCP measurements, or the velocity-area method. If there is already a hydrological station upstream, data from the same day or hour should be used first; if there is no hydrological station, at least one flow measurement should be conducted during the dry season, normal water season, and wet season.

[0054] (2) Water level data acquisition: Water level gauges or pressure gauges are installed at sections S0, S2 and S4, and the online recording interval is no more than 30 minutes; during the high incidence of algal blooms, the recording interval is recommended to be 5-10 minutes. Water level data is used to determine the amplitude of water level fluctuations, control changes in water volume and downstream water level safety constraints.

[0055] (3) Velocity data acquisition: The surface, middle and near-bottom velocities were measured at sections S2, S3 and S4 using ADCP or portable current meters. The basic survey was conducted at least once a month; during the peak period of algal blooms, it was conducted at least once a week; when pulse scheduling was implemented, measurements were taken before, during and after the scheduling to assess the disturbance effect.

[0056] (4) Calculation of hydraulic retention time: based on the control water volume V and the discharge flow rate. Calculate the hydraulic residence time Tres.

[0057]

[0058] In the formula, V is the hydraulic residence time, in seconds (s) or days (d); V is the volume of the control water body, in cubic meters (m³). 3 ; The discharge flow rate is expressed in cubic meters (m³). 3 / s; To avoid division by zero, the minimum flow rate can be set to 0.001 m. 3 / s or as determined by the instrument resolution. The larger the dam, the easier it is for water to stagnate in front of the dam, and the higher the risk of algal blooms.

[0059] (5) Calculation of insufficient flow velocity: Set the critical flow velocity vc for easy algae aggregation. It can generally be determined based on local measured data, indoor disturbance experiments or flow velocities during historical algal blooms. For initial application, 0.05-0.10 m / s can be used as the discrimination range.

[0060]

[0061] In the formula, The value for insufficient flow rate is 0-1. The average flow velocity of the river section is measured in m / s. The critical flow velocity is denoted as . The closer it is to 1, the more severe the flow rate is, indicating that the flow rate is seriously insufficient or close to stagnation.

[0062] S2.3 Water quality and algae data (1) Conventional water quality indicators: Water temperature, pH, dissolved oxygen, turbidity, conductivity, transparency, total nitrogen (TN), total phosphorus (TP), ammonia nitrogen, nitrate nitrogen, permanganate index, or chemical oxygen demand (COD) were collected at each cross-section. On-site indicators (such as water temperature, pH, dissolved oxygen, turbidity, conductivity, and transparency) were directly measured using a multi-parameter water quality analyzer, while laboratory indicators were tested according to current water quality analysis methods.

[0063] (2) Algal indicators: At least two indicators should be collected: chlorophyll a (Chla) and algal cell density. Chlorophyll a can be continuously monitored using an online fluorescence probe and periodically verified using laboratory spectrophotometry; algal cell density should be determined by microscopic counting or flow cytometry. The recommended interval for online chlorophyll a monitoring is 10-30 min, which can be increased to 5-10 min during periods of high algal bloom.

[0064] (3) Sampling time: The basic survey period should cover at least the dry season, normal water season, wet season and historical high algal bloom period. Routine monitoring should be carried out 1-2 times per month; during the high algal bloom period, it should be carried out 1-2 times per week; when the water temperature is higher than 15 degrees Celsius for 3 consecutive days and chlorophyll a shows an upward trend, intensive monitoring should be initiated, and the frequency should be increased to once a day or online monitoring should be adopted.

[0065] (4) Sample preservation and verification: Chlorophyll a samples should be stored in the dark and at low temperature and analyzed as soon as possible; online fluorescent chlorophyll a samples should be verified at least once a month using laboratory measurements, and once a week during periods of high algal bloom. Linear regression can be used for verification.

[0066] In the formula, The value is the laboratory chlorophyll a measurement. The readings are from the online probe; a and b are correction factors. Subsequent risk calculations will preferentially use the corrected chlorophyll a concentration.

[0067] S2.4 Meteorological and Sunlight Data S2.4.1 Data Acquisition: Collect data on temperature, precipitation, wind speed, wind direction, solar radiation, sunshine duration, and cloud cover from meteorological stations or automatic weather stations near the target river section. If there is no meteorological station on site, a small meteorological station should be set up in an open area in front of the dam, with recording intervals not exceeding 1 hour.

[0068] S2.4.2 Light Efficiency Processing: For river sections lacking solar radiation data, sunshine duration or shortwave radiation reanalysis data can be used as substitutes. When used for algal growth suitability calculations, the average daily light intensity can be normalized to the 0-1 range.

[0069] In the formula, The value represents the suitability of lighting, ranging from 0 to 1. The average daily irradiance or shortwave radiation; The half-saturation illumination constant can be calibrated using local data. For initial application, it can be taken as the corresponding historical algal bloom date. median.

[0070] S2.5 Auxiliary Survey of Exogenous Inputs and Shoreline Retention The investigation focuses on identifying sources of exogenous nutrient input and areas prone to algal blooms in the controlled river sections. It clarifies nutrient replenishment pathways and high-risk retention points, providing support for setting nutrient risk factor thresholds, deploying key inspection points, and selecting appropriate scheduling combinations. This is a basic survey component, conducted only in preliminary engineering investigations or in river sections where algal blooms occur repeatedly, and is not included in the real-time calculations for daily gate scheduling.

[0071] (1) Point source and inflow nutrient survey: In the controlled river section and upstream within 1-3 km, investigate the input sources that may affect the accumulation of nutrients in front of the dam, such as domestic sewage outlets, agricultural drainage outlets, aquaculture tailwater outlets, and tributary confluences. Record their location, drainage period, estimated flow rate, and main indicators such as total nitrogen and total phosphorus.

[0072] (2) Investigation of riverbank retention and algae accumulation areas: Use UAV imagery, remote sensing imagery, or on-site inspections to identify riverbank farmland, residential areas, aquaculture ponds, dense aquatic plant zones, backflow bays, riverbank retention waters, and historical algae accumulation areas. Set up more frequent inspection points in areas that may cause local algae accumulation, and use these points as the basis for the layout of S3 algae accumulation sections or riverbank retention units in subsequent scheduling.

[0073] (3) Investigation of endogenous release of sediment: When there is no obvious external input in the controlled river section but algal blooms still occur repeatedly, or when monitoring shows that the dissolved oxygen in the bottom layer is low and the total phosphorus is consistently high, sediment samples of 0-10 cm in the surface layer can be collected at sections S2, S3 and S4 to determine the total nitrogen, total phosphorus, organic matter and nitrogen and phosphorus concentrations in the sediment and interstitial water; when conditions permit, indoor static release experiments can be used to estimate the risk of nutrient release from the sediment.

[0074] S2.6 Data Quality Control and Standardization Processing S2.6.1 Time Scale Unification: Online monitoring data, manual sampling data, gate operation data, and meteorological data are unified into two data tables: one on an hourly scale and one on a daily scale. The hourly scale is used for scheduling triggering and execution, while the daily scale is used for risk trend analysis and parameter correction.

[0075] S2.6.2 Missing rate judgment: Calculate the missing rate R_miss for each type of continuous monitoring data.

[0076]

[0077] In the formula, This represents the number of missing test records. The number of records that should be recorded. If the daily missing rate is less than or equal to 20%, interpolation or the average of adjacent time periods can be used to make up the difference; if the daily missing rate is greater than 20%, that day will not be included in the risk index calculation, but manual notes will be retained.

[0078] S2.6.3 Outlier Handling: Data that significantly exceeds the instrument's measurement range, whose sudden changes exceed three times the standard deviation of the mean of the three preceding and following time periods, and for which no on-site cause is recorded, are marked as outliers. Outliers are not deleted directly; the original value, the corrected value, and the reason for the correction should be retained.

[0079] S2.6.4 Spatial Representative Value Calculation: When there are multiple transverse or vertical points on the same cross-section, the representative value of the cross-section is obtained by area weighting or simple averaging. If the algal aggregation point on the shore is significantly higher than the mainstream point, the "mainstream representative value" and the "retention zone representative value" should be retained separately to avoid diluting high-risk information.

[0080] S3 Algal Bloom Risk Index Construction and Risk Level Determination The risk of algal blooms is determined not only by chlorophyll a concentration, but also by algal growth rate, water residence time, water temperature, light intensity, nutrient levels, and insufficient flow velocity. Based on this, multi-source monitoring data is transformed into quantitative indicators that can be triggered for scheduling, a comprehensive algal bloom risk index (HRI) is constructed, and the risk level is output.

[0081] S3.1 Calculation of Basic Risk Factors (1) Chlorophyll a concentration risk factor Based on the corrected chlorophyll a concentration Calculation. Threshold and It can be set according to historical algal bloom data or management requirements; during initial application, it can be... Set to 10-20 ug / L, Set to 50-80 ug / L.

[0082]

[0083] In the formula, This represents the normalized score of chlorophyll a concentration or the risk index of algal concentration, with a value range of 0-1. This represents the chlorophyll a concentration at time t; This indicates the low-risk threshold or initial threshold for chlorophyll a concentration. This represents the high-risk threshold or upper limit threshold for chlorophyll a concentration. The formula uses an interval linear normalization method to convert chlorophyll a concentration into a risk index between 0 and 1, used to characterize the potential risk of increased algal biomass or algal blooms.

[0084] (2) Chlorophyll a growth rate risk factor Used to identify rapid algal growth processes.

[0085]

[0086]

[0087] In the formula, This represents the logarithmic growth rate of chlorophyll a; and These represent the chlorophyll a concentrations at time t and the previous time, respectively. This indicates the time interval between two adjacent monitoring times; This represents a very small positive number, used to avoid the inability to take the logarithm when the chlorophyll a concentration is 0; it can be 0.01. This represents the normalized score or growth risk index of chlorophyll a growth rate. The threshold for high-growth risk can be represented by the data from 3-5 days prior to historical algal blooms. The median is determined. This formula characterizes the relative growth rate of chlorophyll a through logarithmic difference and uses a normalization method to convert it into a risk index between 0 and 1, which is used to identify the potential risk of rapid algal proliferation or algal blooms.

[0088] (3) Hydraulic retention risk factors The calculation formula is as follows:

[0089] This represents the hydraulic residence time normalized score or residence risk index, with a value typically ranging from 0 to 1; Indicates the hydraulic residence time of a water body; The critical residence time for algal accumulation can be determined through statistical analysis of historical algal blooms; if data is unavailable, an initial range of 2-5 days can be used. This formula converts the water retention risk into a standardized index between 0 and 1 by comparing the actual hydraulic residence time with the critical residence time. The closer a value is to 1, the longer the water remains in the body, and the higher the potential risk of algal proliferation or algal blooms.

[0090] (4) Water temperature suitability The effect of temperature on algal growth was characterized using a Gaussian response function, and the calculation formula is shown below:

[0091] In the formula, This indicates the temperature suitability index or temperature limiting factor, and its value range is usually 0-1; This represents the water temperature at time t; This indicates the optimal temperature, which is the temperature at which algal growth or related ecological processes are most suitable to occur; This parameter represents the temperature response width, used to control the rate at which fitness decreases after the temperature deviates from the optimum temperature. The formula uses a Gaussian response function to characterize the effect of temperature on algal growth or chlorophyll a growth. When the water temperature is close to the optimum temperature, Approaching 1; when the water temperature deviates from the optimal temperature, Gradually decrease.

[0092] (5) Nutritional risk factors The calculation is based on the total nitrogen and total phosphorus concentrations, and the formula is as follows:

[0093] In the formula, This indicates the risk index of nutrient salts; This represents the total nitrogen concentration at time t; This represents the total phosphorus concentration at time t; This indicates the total nitrogen reference threshold or risk threshold; This represents the reference or risk threshold for total phosphorus; the thresholds for total nitrogen and total phosphorus can be determined based on regional water quality targets, historical algal bloom thresholds, or management assessment thresholds. If the study area is primarily limited by phosphorus, the weight of the TP item can be increased; if it is primarily limited by nitrogen, the weight of the TN item can be increased. The closer the value is to 1, the higher the level of nitrogen and phosphorus nutrients in the water, and the greater the risk of algal proliferation or eutrophication.

[0094] (6) Hydraulic disturbance insufficiency factor The flow rate deficiency is used in section 2.2.5; the light suitability factor is also considered. The appropriateness of illumination is adopted from section 2.4.2.

[0095] S3.2 Calculation of the Comprehensive Algal Bloom Risk Index (HRI) After dimensionless transformation of the above risk factors, the comprehensive algal bloom risk index is calculated. The comprehensive risk index, which comprehensively reflects the basic conditions for algal growth, growth rate, water retention rate, water temperature suitability, light conditions, nutrient supply, and hydrodynamic disturbance, is calculated using the following formula:

[0096] In the formula, The comprehensive algal bloom risk index at time t, with a value ranging from 0 to 1; , , , , , and Each risk factor is assigned a weight, with the sum of the weights being 1. For initial application, equal weights or expert weighting can be used. After accumulating data for at least one algal bloom season, the weights can be re-determined based on historical algal bloom occurrences using entropy weighting, logistic regression, or random forest importance methods. In the initial application phase where historical data is lacking, it is recommended to use chlorophyll a concentration, growth rate, and hydraulic retention time as the main factors, with weights tentatively set as follows: =0.20, =0.20, =0.20, =0.10, =0.10, =0.10, =0.10. This weight is only used as an initial running parameter and needs to be adjusted based on local test data.

[0097] S3.3 Risk Level Determination and Triggering Conditions To achieve graded identification and dynamic scheduling response to the risk of abnormal algal proliferation in dam retention areas, an algal bloom risk level discrimination and triggering mechanism was constructed based on the comprehensive algal bloom risk index (HRI), the trend of chlorophyll a concentration changes in water bodies, on-site inspection results, and the validity of online monitoring data. This mechanism classifies algal bloom risk into four levels: Level I (low risk), Level II (risk of concern), Level III (early warning risk), and Level IV (scheduling risk), specifically including: Level I Low Risk: HRI < 0.25, algae levels are low and there is no upward trend; Level II Risk Concern: 0.25≤HRI<0.50, conditions for algal growth are present but no significant aggregation has yet occurred; Level III warning risk: 0.50≤HRI<0.75, or Chla rises for 3 consecutive days with a cumulative increase of more than 10%-20%, indicating rapid algal growth or significant water stagnation; Level IV scheduling risk: HRI≥0.75, or Chla exceeds the control threshold and lasts for 2-3 days, indicating a high probability of algal bloom or local clustering. If the HRI calculation level is inconsistent with the on-site inspection results, the principle of strict risk management shall be followed, and the response measures shall be implemented according to the higher risk level.

[0098] In actual operation, risk level determination should not only be based on the daily HRI calculation results, but also comprehensively adjusted by considering the continuous trend of Chla changes, the stability of online monitoring data, and the results of on-site inspections. If the HRI calculation level and the on-site inspection results are inconsistent within the same day, the principle of strict risk assessment should be followed, and response measures should be implemented according to the higher risk level.

[0099] When online sensors exhibit missing data, abrupt changes, drift, continuous constant values, or significant deviations from manual sampling results, the use of abnormal sensor data in HRI calculations should be suspended. Manual sampling results, on-site inspection results, and data from adjacent monitoring points should be used as temporary criteria for judgment. The sensor can only be reinstated in the risk index calculation after it has returned to normal and completed calibration.

[0100] In addition, the Chla control threshold can be determined based on water body function objectives, historical algal bloom levels, regional water quality management requirements, and engineering scheduling constraints. For drinking water sources, important ecologically sensitive areas, or reservoir bays and backwater areas prone to algal accumulation, stricter Chla control thresholds can be adopted; for river sections with good hydrodynamic exchange conditions and low historical algal bloom risk, the threshold can be appropriately adjusted based on multi-year monitoring data.

[0101] S4, Scheduling Period Identification The scheduling period is dynamically identified by combining inflow rate, hydraulic retention time, water temperature, light intensity, nutrients, and HRI risk level.

[0102] (1) Low water retention period: when the inflow rate Q in It is below the 25th percentile for the same period over many years, and the hydraulic residence time Greater than the critical residence time At this time, it is determined that the controlled river section has entered a period of low water retention. During this period, the water renewal capacity in front of the dam is weak, and the key scheduling objective is to ensure the ecological base flow and avoid prolonged stagnant water through minor disturbances.

[0103] (2) Identification of the water level maintenance period: when the inflow rate Q inWhen the water level is between the 25th and 75th percentiles of the same period over many years, the HRI is at level I or II, and chlorophyll a has not shown a continuous increase, it is considered to be in the water level maintenance period. During this period, the main methods are routine ecological base flow, low-frequency inspections, and necessary minor adjustments to the gates.

[0104] (3) Identification of the high-water flushing period: When the inflow rate Q in A period of high water flow and scouring is defined as a time when water levels are above the 75th percentile for the same period over multiple years, or when weather forecasts indicate a significant rainfall-runoff event in the next 24-72 hours. During this period, natural inflows can be used to enhance water exchange and scouring in front of the dam, but flood control safety and downstream water level fluctuation constraints must be prioritized.

[0105] (4) Identification of high algal bloom period: When the water temperature is above 15 degrees Celsius for more than 2 consecutive days, the light is suitable, the nutrient risk factor is high and the HRI reaches level II or above, it is determined to be a high algal bloom period. If historical data shows that algal blooms occur frequently in certain months, the corresponding months can be designated as key monitoring periods, and the online monitoring frequency and dispatch preparedness level should be increased.

[0106] (5) Identification of special sensitive periods: When there are sensitive needs such as drinking water source intake, water use for major events, ecological water replenishment, fish spawning and reproduction, or water-related construction downstream, the period is marked as a special sensitive period. Even if the HRI is high during the special sensitive period, scheduling should be carried out in a small pulse, multiple frequency, and slow rise and fall manner to avoid sudden impact on downstream water level, water quality and habitat.

[0107] During the aforementioned scheduling periods, the low-water retention period, the normal-water maintenance period, and the high-water scouring period primarily reflect hydrological inflow conditions, while the high-incidence period of algal blooms and the special sensitive period can be used as overlay identification labels. When conditions for multiple time periods are met simultaneously, the final scheduling mode should be determined according to the principle of "flood control safety first, special sensitive constraints first, algal bloom risk prevention and control second, and routine operation last."

[0108] S5, Generation of Gate Ecological Scheduling Scheme Using the risk level output by S3 as the intensity benchmark and the scheduling period output by S4 as the scenario constraint, the corresponding candidate gate action sequence is matched. Then, safety verification and screening are carried out based on constraints such as upstream water level, inflow, ecological base flow, maximum safe discharge, downstream water level fluctuation and gate opening and closing rate. Finally, the executable gate opening degree, discharge flow, duration, water level fluctuation amplitude and stopping conditions are output.

[0109] S5.1 Determination of Basic Scheduling Parameters (1) Determination of ecological base current: ecological base current Priority should be given to using ecological flow data approved by the relevant authorities, engineering scheduling procedures, or ecological flow verification results. If a formal verification value is unavailable, the multi-year average flow Q can be used temporarily during the technical briefing phase. avgA certain percentage of the initial design is required and confirmed by the management department before the project is implemented.

[0110]

[0111] In the formula, For ecological base flow; This refers to the approved ecological flow. The average flow over many years; This is the ecological flow ratio coefficient, which can be determined in conjunction with regional management requirements; To maintain the minimum flow rate for continuous downstream water flow, this formula determines the ecological base flow by taking the maximum value of multiple constraints, ensuring that the downstream discharge flow rate during scheduling is not lower than the management requirements, the ecological water demand requirements based on the proportional method, and the minimum operating requirements of the project.

[0112] (2) Determination of adjustable water storage capacity: The amount of water available for water level fluctuations is calculated based on the normal water level, the minimum control water level and the water surface area of ​​the control section.

[0113]

[0114] In the formula, To utilize the available water storage capacity; To control the average water surface area of ​​the river section; To regulate the water level in front of the dam; This is the minimum control water level.

[0115] (3) Determination of target water exchange ratio: The target water exchange ratio of the controlled river section is determined according to the risk level. For initial application, the risk threshold can be set at 0.05-0.10 for Level II concern, 0.10-0.25 for Level III early warning risk, and 0.25-0.50 for Level IV scheduling risk. For water sources, sensitive ecological areas, or river sections with severe algal blooms, the target water exchange ratio can be appropriately increased.

[0116]

[0117] In the formula, The target pulse water exchange volume within one or one scheduling cycle; V represents the target water exchange ratio; V is the water volume of the control river section calculated in step 1.

[0118] (4) Initial calculation of pulse flow rate and duration: The pulse duration is determined based on the target pulse water exchange volume and the executable discharge flow rate.

[0119]

[0120] In the formula, This refers to the duration of the pulsed discharge. This refers to the discharge flow rate during the pulse period; This is the initial discharge flow before scheduling; To avoid a minimum value where the denominator is zero, we can take 0.01. If the calculated... If the allowed duration is exceeded, the target for a single water change should be reduced and replaced with multiple small pulses.

[0121] (5) Calculation of water level fluctuation range: Under the premise of meeting the minimum control water level and downstream safety, the water level fluctuation range is determined according to the target disturbance water volume and water surface area.

[0122]

[0123] In the formula, The designed water level drop range; To allow the maximum fluctuation range of water level; The amount of water to be allocated for water level fluctuations; To manage the water area; This indicates the theoretically achievable water level change under given water volume and surface area conditions. (This refers to the initial application of small sluice gates / dams.) The depth can be 0.10-0.30 m; if the risk of algal bloom scheduling is high and engineering conditions permit, it can be increased to 0.30-0.50 m.

[0124] (6) Conversion between gate opening and discharge flow rate When a gate opening-flow rate calibration curve already exists, the target gate opening should be calculated using the measured calibration curve first. When a calibration curve is missing, the empirical relationship of gate outflow can be used for preliminary calculation, and then corrected based on the measured flow rate during subsequent operation.

[0125]

[0126] In the formula, To release the flow rate; denoted as ρ = ρ_flow coefficient; B is the effective width of the gate opening; G is the gate opening degree; g is the acceleration due to gravity, typically 9.81 m / s². 2 ; This represents the head difference before and after the gate. The formula is based on orifice outflow theory, calculating the gate discharge flow rate using the orifice's cross-sectional area and theoretical outflow velocity, and then correcting for actual flow conditions using a flow coefficient.

[0127] Calculate the target gate opening based on the target discharge flow rate:

[0128] In the formula, The target gate opening; The target discharge flow rate. If the calculated... If the opening is less than the minimum controllable opening Gmin or greater than the maximum opening Gmax, it should be corrected according to the actual adjustable range of the gate, and the achievable opening should be recalculated. .

[0129] When operating multi-gate systems, symmetrical or staged opening should be prioritized to avoid flow deviation, localized scouring, and uneven stress on the gates. If algae in front of the dam are mainly concentrated on a certain bank or in the backflow area, the gates closer to the algae accumulation area can be opened first, provided it is safe to do so, to enhance local water exchange.

[0130] S5.2 Candidate Scheduling Sequences by Risk Level like Figure 3 As shown, the scheduling sequences are as follows: S5.2.1 Level I Low-Risk Conventional Ecological Baseflow Sequence (1) Start-up conditions: HRI<0.25, chlorophyll a is at a low level and has no continuous upward trend, and no algal aggregation was found during on-site inspection.

[0131] (2) Scheduling action: Maintain Q out Not lower than Q eco Maintain the water level in front of the sluice gate within the normal operating range; collect water quality and hydrological data at the regular frequency.

[0132] (3) Gate control: If the gate is automatically controlled, the opening G should be maintained at a level that satisfies Q. out >= Q eco The minimum stable opening degree; if manual control is used, daily inspection records should be generated, including gate opening degree, water level, flow rate and equipment status.

[0133] (4) Criteria for stopping or upgrading: If the HRI rises to Level II, or if Chla rises for 2-3 consecutive days, the normal ecological base flow sequence will be upgraded to a Level II attention and prevention sequence.

[0134] S5.2.2 Level II Risk Monitoring and Underlying Micro-Perturbation Preparation Sequence (1) Start-up conditions: 0.25 <= HRI < 0.50, or suitable water temperature, light and nutrient conditions but chlorophyll a has not exceeded the control threshold.

[0135] (2) Scheduling actions: Increase the online monitoring interval to 5-10 min; conduct manual inspections focusing on the S3 algae aggregation section and the S4 gate front main control section; prepare to execute the bottom-level micro-disturbance.

[0136] (3) Micro-disturbance design: Without significantly changing the water level in front of the dam, short-term gate fine-tuning is carried out 1-2 times a day before and after the period when the sunlight is strong and algae are easy to float, so that the flow velocity in the near bottom or main flow area reaches 0.05-0.10 m / s, and the duration of each adjustment is 15-30 min. Bottom micro-disturbance is used when bottom outlets, low-level discharge outlets, or conditions that can increase the near bottom flow velocity are available; when these conditions are not available, small pulse disturbance in the main flow area is used. The calculation formula is as follows:

[0137] In the formula, For flow rate under slight disturbance; The amplification factor for the micro-disturbance flow can be initially set to 1.1-1.5; This is the ecological base flow. After the micro-disturbance ends, the gate opening returns to the opening corresponding to the normal ecological base flow. This formula determines the discharge flow during the micro-disturbance scheduling by setting a micro-disturbance amplification coefficient based on the ecological base flow constraint. This is used to enhance local hydrodynamic disturbance while ensuring basic ecological water demand, and to reduce the risk of water retention and algae accumulation.

[0138] (4) Upgrade conditions: If Chla continues to rise within 24 hours after the micro-perturbation, or HRI rises to level III, then enter the level III early warning intervention sequence.

[0139] S5.2.3 Level III Early Warning Risk: Bottom-level Micro-disturbances and Small-Pulse Water Exchange Sequence (1) Start-up conditions: 0.50<=HRI<0.75, or Chla rises for 3 consecutive days, or local water color abnormalities are found during on-site inspections, and algae gather on the shore but have not yet formed a large area of ​​floating algae belt.

[0140] (2) Scheduling objectives: to shorten the hydraulic residence time of the controlled river section, increase the flow velocity of the main control section in front of the gate and the retention area on the bank, and inhibit the continued proliferation of algae.

[0141] (3) Small pulse water exchange design: small pulse discharge flow rate The water exchange rate can be determined as 1.5-2.5 times the ecological base flow, with each exchange lasting 0.5-2 hours, once a day or every other day, and the target water exchange ratio Rtarget is 0.10-0.25.

[0142] The small-pulse scheduling flow is determined based on the ecological base current and the amplification factor, using the following formula:

[0143] When the small-pulse scheduling process adopts the "slow rise-maintain-slow fall" gate operation mode, its effective water exchange volume is not calculated based on a single constant flow rate, but rather calculated cumulatively in stages throughout the entire process:

[0144] The proportion of water volume allocated via small pulse scheduling to the target water body volume is calculated using the following formula:

[0145] In the formula, The effective water exchange volume generated by small pulse scheduling; This represents the actual water exchange ratio of the small pulse. The actual or designed discharge flow rate at time t; This refers to the initial discharge flow or regular operating flow before scheduling; V represents the time step for calculation; V represents the volume of water in the control river section.

[0146] When the gradual rise and fall phases are treated approximately as linear flow changes, the above cumulative formula can be simplified to:

[0147]

[0148] In the formula, The time required for the gate to gradually increase from its base opening to its target opening. Duration for maintaining the target traffic; This is the descent time for the gate to recover from the target opening to the base opening. If the calculated... If the water exchange rate is less than the target rate Rtarget, the interval should be extended appropriately. ,improve Alternatively, the number of small pulse executions can be increased; if constrained by water level, downstream flow, or gate opening and closing rate, the target for a single water exchange should be reduced, and multiple small pulse executions should be performed instead.

[0149] (4) Gate operation process: The gate opening should be changed in a "gradual rise - hold - gradual fall" manner. During the gradual rise phase, the gate will be changed from the basic opening G. base Gradually adjust to the target opening G small During the maintenance phase, maintain the target flow rate; during the gradual reduction phase, gradually restore the flow to the basic level to avoid sudden rises and falls in downstream water levels.

[0150] (5) Termination conditions: If the Chla growth rate turns negative within 24 hours after scheduling, the HRI drops below Level II, and no new algal aggregation is observed during on-site inspection, the small pulse can be stopped and the Level II attention and prevention sequence can be entered. If Chla continues to rise or the HRI rises to Level IV, the Level IV scheduling risk combination sequence should be entered.

[0151] 5.2.4 Level IV Dispatch Risk: Combination Sequence of Pulse Water Release and Water Level Fluctuation (1) Start-up conditions: HRI>= 0.75, or Chla exceeds the control threshold and lasts for 2-3 days, or there are obvious floating algae belts, abnormal water color in front of the gate, and expansion of algae aggregation area on site.

[0152] (2) Scheduling objective: By using short-term strong outflow and water level periodic fluctuations, the stable aggregation state of algae on the surface is disrupted, the vertical mixing and horizontal exchange of water are improved, and the algae concentration in front of the dam is reduced.

[0153] (3) Pulse flow design: The pulse discharge flow rate Qpulse can be initially set at 2.0-4.0 times the ecological base flow, or determined by back calculation based on the target water exchange ratio. The specific value shall not exceed the maximum safe discharge Qsafe and the downstream allowable flow rate Qdown,max. The calculation formula is as follows:

[0154] In the formula, For pulse-based flow scheduling; This represents the pulse scheduling flow amplification factor, which can be determined based on the dam size, downstream capacity, and historical scheduling effects. Indicates ecological base current; The allowable flow rate for engineering safety or the safe discharge flow rate of the dam; This represents the maximum safe flow allowed in the downstream river channel or the maximum flow that the downstream control section can withstand. This formula determines the maximum executable flow rate during a pulsed discharge process by comprehensively considering ecological scheduling needs, engineering safety constraints, and downstream flood control safety constraints.

[0155] (4) Pulse duration design: Calculate the duration of a single pulse based on the target water exchange ratio and the executable pulse flow rate. If the duration of a single pulse exceeds 3 hours or the water level drops beyond the allowable range, it should be divided into multiple pulses. The calculation formula is as follows:

[0156] In the formula, Indicates the duration of pulse scheduling; Indicates the target water exchange ratio; The volume of the water body to be scheduled; Indicates pulse scheduling flow; This indicates the basic discharge flow or normal operating flow. To avoid setting a tiny positive number where the denominator is zero, a value of 0.01 can be used. This formula determines the water volume required for pulse scheduling based on the target water exchange ratio, and calculates the scheduling time required to complete the water exchange target by effectively increasing the discharge flow.

[0157] (5) Water level fluctuation design: Water level fluctuations should be designed to avoid exceeding the minimum control water level, affecting water intake, and causing bank erosion. Methods such as "discharge before storage," "daytime discharge and nighttime storage," or "short-cycle rise and fall" can be adopted. Water level fluctuation amplitude... The settings can be configured in increments of 0.10-0.50 m, with a cycle time of 6-24 hours. The calculation formula is as follows:

[0158] In the formula, This is the current water level in front of the dam; The water level for the next time period; For inbound traffic; To release the flow rate; To calculate the time step; The average water surface area is denoted by . This formula is based on the principle of water balance, calculating the change in water volume per unit time using the difference between inflow and outflow, and converting it into a change in water level to describe the dynamic response of water level during scheduling.

[0159] (6) Combination method: When there are obvious floating algae on the surface, the combination of "pulse discharge + water level drop" should be given priority; when the algae mainly gather in the stagnant bay on the shore, the combination of "water level fluctuation + short-term repeated micro-disturbance" should be given priority; when bottom sediment release and low dissolved oxygen exist at the same time, long-term strong discharge should be avoided, and multiple short pulses should be used to enhance bottom exchange.

[0160] (7) Stop conditions: When Chla drops below the control threshold, HRI is calculated twice consecutively and drops below level III, and on-site inspection confirms that the floating algae belt has disappeared, stop level IV combined scheduling and switch to level III or level II maintenance mode.

[0161] S5.2.5 Coordinated Scheduling Sequence for High-Water Scrub (1) Activation conditions: It is in the period of high water flushing, and there is a usable rainfall runoff process in the next 24-72 hours, or the upstream water has increased significantly.

[0162] (2) Dispatch actions: Without lowering the flood control safety standard, utilize natural water inflow to form water exchange in front of the dam. If the forecast water inflow is large, a small amount of pre-discharge can be carried out in advance to leave storage capacity for subsequent water inflow; if the water inflow has already arrived, a moderate flushing process can be formed by controlling the gate opening.

[0163] (3) Control principles: The goal of flushing during high water flow is not to maximize discharge, but to achieve the target water exchange ratio, avoid sudden changes in downstream water level, and reduce algae retention. During scheduling, the upstream inflow and downstream water level should be tracked in real time, and flushing should be stopped or reduced immediately if necessary.

[0164] S5.3 Safety and Execution Constraints of Impulse Disturbance Scheduling Scheme After the candidate scheduling sequences are generated, each one should be checked for safety constraints. For example... Figure 4 As shown, only solutions that simultaneously satisfy the following constraints can be output as executable solutions.

[0165] (1) Ecological baseflow constraints: This means that the downstream flow rate at any given time must not be lower than the ecological base flow. This constraint is used to ensure that the downstream river continues to flow during the scheduling process and to meet basic ecological water demand requirements.

[0166] (2) Maximum safe discharge limit: This means that the discharge flow at any given time must not exceed the smaller of the maximum allowable safe discharge capacity of the dam project and the maximum allowable flow rate of the downstream river channel. This constraint is used to prevent sudden rises in downstream water levels, riverbank erosion, flooding, or damage to water intake facilities caused by excessive pulse discharge.

[0167] (3) Water level constraints in front of the dam: During the scheduling process, the water level in front of the dam must be maintained within the allowable operating water level range. This constraint is used to ensure that the water level during scheduling does not fall below the minimum water level required for water supply, landscaping, ecology, or equipment operation, nor does it exceed the maximum allowable water level of the project.

[0168] (4) Downstream water level fluctuation constraint: abs( This means that the rate of change of downstream water level per unit time must not exceed the allowable value. In the formula, This represents the maximum permissible rate of water level change downstream. This constraint is used to prevent sudden rises and falls in downstream water levels caused by the sudden opening or closing of the gate.

[0169] (5) Gate opening and closing rate constraint: That is, the change in gate opening degree per unit time must not exceed the allowable speed of the hoist. Where: G(t) is the gate opening degree at time t; G(t+dt) is the gate opening degree at the next time step; To calculate the time step; This is the maximum allowable opening and closing rate for the gate. This constraint is used to protect the gate and hoisting equipment, while preventing sudden changes in the discharge flow rate caused by the gate opening or closing abruptly.

[0170] (6) Dual Constraints of Dispatched Water Exchange and Reservoir Capacity Consumption: The dispatched water exchange is used to evaluate the contribution of pulse disturbances to water exchange in the controlled river section, while the reservoir capacity consumption is used to verify whether the water level in front of the dam meets the minimum control water level and the requirements for water supply, landscape, and ecological operation during the dispatching process. The dispatched water exchange is calculated based on the increase in the dispatched discharge flow relative to the basic discharge flow:

[0171]

[0172] In the formula, To regulate the water exchange volume; This represents the actual water exchange ratio; The outflow is scheduled at time t; This refers to the initial discharge flow or regular operating flow before scheduling; V represents the time step for calculation; V is the volume of water in the control river section.

[0173] Storage capacity consumption is calculated based on the net increase in scheduled outflow relative to the inflow during the same period:

[0174]

[0175]

[0176] In the formula, This represents the net water consumption in front of the dam during the scheduling period; Let t be the inflow rate; The available water storage capacity; To control the average water surface area of ​​the river section; To regulate the water level in front of the dam; This is the minimum control water level.

[0177] S5.4 Scheduling Sequence Encoding and Output To facilitate automatic invocation and manual review, each scheduling sequence adopts a unified encoding format:

[0178] In the formula, This is the k-th candidate scheduling sequence; Level indicates the applicable algal bloom risk level for this scheduling sequence; Period is the applicable scheduling period. This is the initial gate opening. The target opening degree of the gate; Discharge flow to the target; The gradual increase time for the gate to adjust from its initial opening to its target opening; Duration for maintaining the target traffic; dH is the time for the gate to gradually return to its normal opening from the target opening; f is the water level fluctuation amplitude caused by the scheduling process; Stop is the scheduling stop condition.

[0179] The final output scheduling plan should include: scheduling trigger basis, gate action, discharge process, water level process, safety verification results and stopping conditions. The specific contents of each item are shown in the table below.

[0180] Table 1 Output Contents of the Gate Ecological Dispatch Scheme

[0181] The scheduling plan can generate automatic control commands or scheduling orders for manual approval. When automatic control is used, the system should send the target opening degree and opening / closing process to the gate control equipment; when manual control is used, the dispatcher should execute each item according to the scheduling order and record the actual opening degree, actual water level, actual flow rate, and execution time.

[0182] S6 Real-time Monitoring, Early Warning and Gate Scheduling Execution By accessing real-time monitoring data and gate operation status, the gate opening and closing operations are executed according to the established scheduling plan. The entire process monitors hydrodynamics, water quality, and equipment conditions. In case of abnormal conditions, the scheduling is adjusted or suspended immediately. The entire execution process is fully recorded to ensure that scheduling actions are started on time, operation is controllable, abnormalities can be handled, and results are traceable.

[0183] S6.1 Real-time Data Access Online monitoring data access: Chlorophyll a, water temperature, pH, dissolved oxygen, turbidity, water level, flow velocity, and meteorological data are connected to the central control platform. During normal periods, the data upload interval can be 10-30 minutes; during periods of high algal blooms and scheduling operations, this interval should be increased to 5-10 minutes.

[0184] Gate operation data access: Real-time acquisition of gate opening degree, hoist status, upstream water level, downstream water level, and discharge flow. If data cannot be acquired automatically, operators should manually record the data before, during, and after dispatching.

[0185] Data validity check: Before each HRI calculation and scheduling instruction issuance, the system should check whether the sensor is missing, drifting, continuously constant, or exceeding its range. If critical data is abnormal, the system should switch to manual review mode.

[0186] S6.2 Scheduling Startup Process Automatic early warning: The system calculates the HRI according to a set time step. When the HRI reaches level II or above, an early warning message is generated; when it reaches level III or IV, the system automatically matches candidate schemes in the scheduling sequence library.

[0187] Manual verification: For Level III and Level IV dispatches, operators should verify information such as on-site water color, algae accumulation, water intake facilities, downstream construction, and weather forecasts before execution. If the on-site conditions are inconsistent with the HRI level, adjustments should be made according to the principle of strict risk management or the principle of safety priority.

[0188] Activation condition confirmation: Gate scheduling can only be activated when the equipment is in normal condition, there is no prohibition on discharge downstream, the water level in front of the dam meets the scheduling water volume requirements, and the scheduling plan passes the safety constraint verification.

[0189] S6.3 Gate Execution Process Gradual opening phase: Following the opening and closing rate calculated in step S5, gradually increase the gate opening from the initial opening Gstart to the target opening Gtarget. During the gradual opening phase, the downstream water level should be monitored in real time. If the water level rise exceeds the warning value, further opening should be suspended.

[0190] Maintenance Phase: After the gate reaches the target opening, maintain the target discharge flow rate Qtarget until the design duration. During the maintenance phase, focus on monitoring changes in Qout, H, Chla, DO, and flow velocity to determine if the disturbance has reached the target.

[0191] Slow-down phase: After the designed duration is reached, the gate gradually returns to its basic opening at a set rate. During the slow-down phase, a rapid drop in downstream water level should be avoided; if necessary, a staged drop method should be adopted.

[0192] Water level fluctuation phase: When the plan includes water level fluctuations, the water level in front of the dam should be raised and lowered by intermittent opening and closing of the gates. The water level drop phase is used to enhance the output of surface algae and disturb the shore retention zone; the water level rise phase is used to restore the necessary water storage level and reduce ecological impact.

[0193] S6.4 Handling Abnormal Operating Conditions During the scheduling process, if situations such as a rapid rise in downstream water levels, gate malfunction, communication interruption, sudden heavy rainfall, abnormal water intake, rapid drop in dissolved oxygen, or abnormal increase in algae concentration occur, abnormal operating condition handling should be initiated immediately. Handling methods include suspending continued gate opening, reducing the target flow rate, prematurely ending the pulse process, switching to manual control, or restoring the normal ecological base flow.

[0194] S6.5 Scheduling Record Each dispatch should be documented in its entirety, including dispatch number, risk level, reason for initiation, execution time, gate opening process, discharge flow process, water level process, online water quality changes, on-site photos, any abnormal situations, and the personnel involved. The dispatch record serves as the foundational data for the effectiveness evaluation and parameter correction in step 7.

[0195] S7 Scheduling Performance Evaluation and Adaptive Parameter Adjustment This step is used to determine whether the ecological scheduling of the gate has achieved the goal of algae control, and to update the HRI threshold, risk weight and scheduling sequence parameters based on the measured results, so that this technology can be adapted to different gates, different seasons and different water inflow conditions.

[0196] S7.1 Data Acquisition Before and After Scheduling For each scheduling operation, data on chlorophyll a, water temperature, dissolved oxygen (DO), pH, turbidity, flow velocity, water level, and flow rate should be obtained at least before, during, 1 hour after, 6 hours after, 24 hours after, and 48 hours after the scheduling operation. If the target of the scheduling operation is at Level IV risk, on-site inspections should be conducted simultaneously, and the algal accumulation area, water color changes, and location of floating algal belts should be recorded.

[0197] S7.2 Calculation of Key Performance Indicators The chlorophyll a reduction rate is calculated using the following formula:

[0198] In the formula, The chlorophyll a reduction rate; This represents the value before scheduling; Chla after This represents the value for a specified time period after scheduling.

[0199] The growth rate inhibition rate is calculated using the following formula:

[0200] In the formula, Er is the chlorophyll a growth rate reduction rate, i.e. growth risk suppression efficiency; To regulate the growth rate of chlorophyll a in the anterior leaves; The growth rate after scheduling; To avoid the use of a tiny positive number where the denominator is zero, we can use 0.01.

[0201] The actual water replacement ratio is calculated using the formula shown below:

[0202] In the formula, In order to adjust the water exchange rate, The actual discharge flow rate at time t; This is the normal operating traffic. To calculate the time step; This represents the cumulative amount of water released in addition to the base flow rate during the entire scheduling process; To calculate the total water volume, this formula evaluates the degree of water exchange during the ecological regulation of the gate by accumulating the effective discharge volume relative to the base flow during the scheduling period and comparing it with the volume of the scheduled water body.

[0203] The unit water exchange reduction efficiency is calculated using the following formula:

[0204] In the formula, The efficiency reduction per unit of water exchange. The chlorophyll a reduction rate; To adjust the water exchange rate; To avoid using a tiny positive number where the denominator is zero, a value of 0.01 can be used. This formula evaluates the contribution efficiency of unit water exchange volume to algal biomass reduction during the gate ecological scheduling process by comparing the chlorophyll a reduction rate with the cumulative water exchange ratio. It can be used to compare the effects of different scheduling schemes.

[0205] The downstream water level change rate constraint index is calculated using the following formula:

[0206] In the formula, This represents the maximum rate of change in downstream water level. Let t be the water level at the downstream control section. This refers to the water level at the downstream control section in the previous time step. To calculate the time step, this formula calculates the ratio of the downstream water level change amplitude at adjacent moments during the scheduling period to the time step, and takes the maximum value. This is used to evaluate whether the downstream water level fluctuations during the gate's ecological scheduling meet safety control requirements. When If the allowable value is exceeded, even if the algae reduction effect is good, the plan should be judged to have safety or management risks.

[0207] S7.3 Scheduling Effectiveness Grading Evaluation The evaluation of scheduling effectiveness should simultaneously consider algae reduction, decrease in algal bloom risk, changes in on-site algal aggregation, and engineering safety status. The evaluation results are shown in the table below, categorized into four types: effective, partially effective, ineffective, and unsuitable for implementation, with corresponding follow-up treatment methods.

[0208] Table 2. Scheduling Effectiveness Grading Evaluation Table

[0209] S7.4 Parameter Adaptive Correction S7.4.1 Adjustment of scheduling sequence parameters: Adjust the flow rate, duration, and frequency of the next pulse based on the actual water exchange ratio and chlorophyll a reduction rate. The calculation formula is shown below:

[0210] In the formula, These are the corrected scheduling parameters; These are the original scheduling parameters; The appropriate parameters are derived by working backward from the scheduling results. The update coefficient can be set to 0.1-0.3. P can represent scheduling parameters such as Qpulse, tpulse, dH, and Rtarget. This formula uses the concept of exponential smoothing to provide feedback corrections for parameters such as pulse flow, scheduling duration, water level fluctuation amplitude, and target water exchange ratio, enabling the scheduling sequence to be gradually optimized based on the actual water exchange effect and chlorophyll a reduction effect.

[0211] S7.4.2 HRI Weight Adjustment: After accumulating data for at least one algal bloom season, the weights can be adjusted based on the relationship between each risk factor and the algal bloom outcome. If a simple update method is used, it can be calculated using the following formula:

[0212] In the formula, The new weights are adjusted for the i-th risk factor; The original weight of the i-th risk factor; The importance of the i-th risk factor in the determination of algal bloom occurrence; It is the sum of the importance of all risk factors; Let i be the normalized importance of the i-th risk factor; Weight Update Coefficient. This formula dynamically adjusts the weights of the HRI Comprehensive Algal Bloom Risk Index by weighting and fusing the original weights with the normalized factor importance obtained from measured algal bloom season data. Risk Factor Importance It can be determined by methods such as correlation analysis, logistic regression, random forest, or expert review.

[0213] S7.4.3 Threshold Correction: When HRI is low multiple times but algal bloom has already occurred on site, the HRI trigger threshold should be lowered or the weight of key factors should be increased; when HRI is high multiple times but algal bloom has not occurred on site, the sensor calibration, nutrient threshold and flow rate threshold should be checked to see if they are too sensitive.

[0214] S7.4.4 Sequence library update: For sequences that are valid multiple times consecutively, mark them as priority sequences; for sequences that are invalid multiple times or have high security risks, reduce their calling priority or restrict their applicable conditions.

[0215] S7.5 Output Results The output includes a single scheduling effect evaluation table, chlorophyll a reduction rate, actual water exchange ratio, unit water exchange reduction efficiency, abnormal operating condition records, corrected HRI threshold or weight, and corrected scheduling sequence library parameters. In summary, the complete closed-loop operation logic formed by this method—"real-time monitoring - risk warning - gate scheduling execution - effect evaluation - parameter adaptive correction"—is as follows: Figure 5 As shown.

[0216] Example 2 The following examples are used to illustrate how this technology is implemented and do not limit the scope of protection of this technology. The river section, flow rate, water level, chlorophyll a, and HRI values ​​in the examples are set to demonstrate the calculation process and have been verified according to the common hydrological and hydrodynamic range of the river section in front of a small dam.

[0217] I. Example of Small Pulse Scheduling for Level III Early Warning Risk The controlled river section upstream of a certain dam is approximately 600 m long, with an average water surface width of about 25 m, an average water depth of about 3.3 m, and a controlled water volume V of approximately 50,000 m³. 3 The average water surface area of ​​the controlled river section, Awater, is approximately 15,000 m². 2 Ecological base current Q eco0.6m 3 / s, the normal operating outflow rate Qbase is 0.7 m 3 / s, the water level H0 in front of the dam before scheduling is 382.00 m, the minimum control water level Hmin is 381.50 m, and the adjustable storage capacity W avail 7500 m 3 .

[0218] Online monitoring during the peak algal bloom period showed that Chla levels rose continuously for three days, from 28 ug / L to 35 ug / L, with a calculated HRI of 0.68, indicating a Level III warning risk. The system selected the "small pulse water exchange" scheme from the scheduling sequence library and set the target water exchange ratio R. target If the value is 0.10, then the target increase in water exchange volume is: V pulse = R target * V = 0.10 * 50000 = 5000 m 3 Based on the ecological base flow and downstream safety conditions, the small pulse flow rate Q is set. small 1.5 m 3 / s, equivalent to 2.5Q eco This meets the recommended range for Level III small pulses. (Relative to the baseline discharge flow rate Q) base =0.7 m 3 / s, with a new discharge capacity of 0.8 m³ / s. 3 / s, calculate the equivalent duration of the target flow: t small = 5000 / (1.5-0.7) = 6250 s = 1.74 h. This duration is within the recommended range of 0.5-2 h, and the additional water volume is 5000 m³. 3 Less than 7500 m³ of adjustable water storage capacity 3 The actual water exchange ratio is approximately 0.10, therefore it can be performed as a single small pulse.

[0219] The gate adopts a "slow rise-hold-slow fall" method, with a slow rise of 15 minutes, a hold period of approximately 1.49 hours, and a slow fall of 15 minutes. If the slow rise and slow fall phases are accounted for as linear opening changes, the effective additional water exchange volume corresponding to the entire process of slow rise, hold, and slow fall is approximately 5000 m³. 3 The actual water exchange ratio was approximately 0.10, which meets the target of this small-pulse scheduling. Downstream water level changes should be monitored synchronously during execution. If the rate of change of downstream water level exceeds the allowable value, the target flow rate should be reduced or the scheduling process should be terminated early.

[0220] 24 hours after execution, Chla levels decreased from 35 ug / L to 24 ug / L, with a chlorophyll a reduction rate of approximately 31.4%; the HRI decreased from 0.68 to 0.46, and the risk level decreased from Level III to Level II; no new algal aggregation was observed during on-site inspection, indicating that the scheduling was effective. The system marked this small pulse sequence as a priority sequence for the dam under similar inflow and temperature conditions. Under subsequent conditions of the same risk, the target water exchange ratio can be initially set at 0.08-0.10 to reduce the cost of water usage during scheduling.

[0221] II. Example of Level IV scheduling risk combination scheduling If subsequent monitoring of the same river section shows that the HRI rises to 0.82, Chla reaches 62 ug / L and exceeds the control threshold for 3 consecutive days, and obvious floating algae appear in the S3 bank retention zone, then the system enters the Level IV scheduling risk mode and selects the "pulse discharge + water level fluctuation" combination sequence.

[0222] In this scheduling, Q is set. safe 3.0 m 3 / s, downstream maximum allowed flow Q down , max 2.5 m 3 / s, the strong pulse coefficient β3 is taken as 3.5, then: Q pulse = min(3.5 * 0.6, 3.0, 2.5) = 2.1 m 3 / s. Set the target water exchange ratio R target If the value is 0.25, then the target water exchange volume is 12500 m³. 3 Relative to the base traffic Qbase=0.7 m 3 / s, the newly added discharge capacity is 1.4 m³ / s. 3 / s, the equivalent duration of the target traffic is: t pulse = 0.25 * 50000 / (2.1 - 0.7) = 8929 s = 2.48h. This duration is less than 3 hours, which meets the control requirements for the duration of a single strong pulse.

[0223] To avoid the target water exchange volume exceeding the available storage capacity, this combined scheduling operation will be conducted under conditions where upstream inflow has already increased. The average inflow Q during the scheduling period is projected. in Approximately 1.68 m 3 / s, then the net storage capacity consumption during the scheduling period is approximately (2.1) 1.68) × 8929 = 3750 m 3 This corresponds to a drop of approximately 0.25 m in the water level in front of the dam. During the scheduling process, the water level in front of the dam is expected to drop from 382.00 m to approximately 381.75 m, which is higher than the minimum control water level of 381.50 m, thus meeting the safety constraints on the water level in front of the dam.

[0224] During combined scheduling, the gate operates in a slow-rise-hold-slow-lower mode. The slow-rise and slow-lowering phases should take into account the effective water exchange volume and water level changes; the target flow rate maintenance time can be adjusted based on the water exchange volume contributed by the slow-rise and slow-lowering phases. If the downstream water level change rate exceeds the allowable value during execution, the system immediately reduces the target flow rate or terminates the pulse process prematurely.

[0225] Forty-eight hours after execution, Chla decreased from 62 ug / L to 36 ug / L, with a chlorophyll a reduction rate of approximately 41.9%; HRI decreased from 0.82 to 0.58, and the risk level decreased from Level IV to Level III; the area of ​​floating algae on site significantly decreased, and no abnormal downstream water levels or water intake risks were observed. Based on the scheduling effectiveness grading evaluation standards, this combined scheduling was deemed effective. Since the HRI remains within the Level III warning risk range, the subsequent process should transition to a Level III small-pulse maintenance mode, and water quality changes should continue to be monitored for 24-48 hours.

[0226] This document uses specific examples 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. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A pulsed ecological scheduling method for controlling algal blooms at dams and sluices, characterized in that, Includes the following steps: S1. Identification of Controlled River Sections and Delineation of Monitoring Units: Conduct engineering surveys of the river sections in front of dams and gates within the target watershed, determine the spatial boundaries of the controlled river sections, calculate the volume V of the controlled water body, and set up monitoring sections and sampling points. S2. Multi-source data acquisition and preprocessing: Acquire dam engineering and operation data, hydrological and hydrodynamic data, water quality and algae data, meteorological and light data, and perform data quality control and unified processing; S3. Construction of Algal Bloom Risk Index and Risk Level Determination: Calculation of Chlorophyll a Concentration Risk Factor S C Growth rate risk factor S r Hydraulic retention risk factor S Tres Water temperature suitability S T Light suitability S I Nutrient salt risk factor S NP and insufficient flow rate S v A comprehensive algal bloom risk index (HRI) was constructed, and algal bloom risks were divided into four levels based on the HRI value: Level I low risk, Level II risk of concern, Level III early warning risk, and Level IV scheduling risk. S4. Dispatch Period Identification: Identify five types of dispatch periods: low water retention period, normal water maintenance period, high water flushing period, high algal bloom period, and special sensitive period, as scenario constraints for dispatch scheme generation; S5. Generation of ecological gate scheduling scheme: Combine the risk level of algal bloom with the type of scheduling period to generate candidate gate action sequences of corresponding intensity. Then, based on the constraints of ecological base flow, maximum safe discharge, upstream water level, downstream water level fluctuation, gate opening and closing rate, and dual constraints of scheduling water exchange and reservoir capacity consumption, safety verification and screening are carried out to output an executable gate scheduling scheme. S6. Real-time monitoring and early warning and gate scheduling execution: Real-time access to online monitoring data and gate operation data, execute gate operations according to the scheduling plan, and immediately handle abnormal operating conditions; S7. Scheduling effect evaluation and adaptive parameter correction: Calculate the chlorophyll a reduction rate, growth rate inhibition rate, actual water exchange ratio, unit water exchange reduction efficiency, and downstream water level change rate constraint indicators, and adaptively correct the scheduling sequence parameters, HRI weight, and trigger threshold based on the evaluation results.

2. The pulsed ecological scheduling method for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The formula for calculating the comprehensive algal bloom risk index (HRI) in step S3 is as follows: The formulas for calculating each risk factor are as follows: In the formula, The comprehensive algal bloom risk index at time t, with a value ranging from 0 to 1; , , , , , and The weights of each risk factor are 1, and the sum of the weights is 1. Let be the chlorophyll a concentration at time t; and These are the low-risk threshold and the high-risk threshold, respectively. This represents the logarithmic growth rate of chlorophyll a. To avoid tiny positive numbers that are zero when their logarithm is taken; This represents a high-growth risk threshold. The hydraulic residence time; The critical residence time at which algal accumulation is likely to occur; Let t be the water temperature. The optimal temperature; This is the temperature response width parameter; and These are the total nitrogen and total phosphorus concentrations, respectively. and This is a reference threshold.

3. The pulsed ecological scheduling method for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The risk level determination rule mentioned in step S3 is as follows: Level I Low Risk: HRI < 0.25, algae levels are low and there is no upward trend; Level II Risk Concern: 0.25≤HRI<0.50, conditions for algal growth are present but no significant aggregation has yet occurred; Level III warning risk: 0.50≤HRI<0.75, or Chla rises for 3 consecutive days with a cumulative increase of more than 10%-20%, indicating rapid algal growth or significant water stagnation; Level IV scheduling risk: HRI≥0.75, or Chla exceeds the control threshold and lasts for 2-3 days, indicating a high probability of algal bloom or local clustering. If the HRI calculation level is inconsistent with the on-site inspection results, the principle of strict risk management shall be followed, and the response measures shall be implemented according to the higher risk level.

4. The method for pulsed ecological scheduling for controlling algal blooms at dams and sluices according to claim 1, characterized in that: In step S4, the scheduling time periods are divided into five categories: During the dry season, the inflow rate is lower than the 25th percentile of the same period over many years and the hydraulic retention time exceeds the critical value, resulting in weak water body renewal capacity. During the period of water level maintenance, the inflow is at the 25th to 75th percentile of the same period over many years and the risk is at level I to II, and the hydrological conditions are stable. During the high-water flushing period, if the inflow is higher than the 75th percentile of the same period in previous years or if significant rainfall runoff is forecast, natural water can be used to assist in water exchange. During the peak period of algal blooms, when the water temperature is above 15℃ for more than two consecutive days, the light is suitable, and the risk level reaches Level II or above, the algal proliferation rate is rapid. During particularly sensitive periods, when there are water intakes, ecologically sensitive targets, or water-related construction downstream, the intensity and rate of scheduling disturbances must be strictly limited.

5. The method for pulsed ecological scheduling for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The candidate gate action sequence in step S5 includes: Level I low risk corresponds to the normal ecological base flow sequence, maintaining the outflow rate at no less than the ecological base flow, maintaining stable operation during the normal and dry seasons, and coordinating with natural water inflow during the wet season; Level II risk corresponds to the underlying micro-disturbance sequence. Short-term gate fine-tuning is carried out 1-2 times daily, with each adjustment lasting 15-30 minutes. The disturbance flow is 1.1-1.5 times the ecological base flow. The lower limit parameter is used during special sensitive periods. Level III early warning risk corresponds to a small-pulse water exchange sequence, which adopts a slow rise-maintenance-slow fall opening and closing method. The flow rate of a single pulse is 1.5 to 2.5 times the ecological base flow, and the duration of a single pulse is 0.5 to 2 hours. The target water exchange ratio is 0.10 to 0.

25. Level IV scheduling risk corresponds to a combination sequence of pulsed discharge and water level fluctuations. The pulsed flow rate is 2.0 to 4.0 times the ecological base flow, the target water exchange ratio is 0.25 to 0.50, and it is coordinated with water level periodic fluctuations of 0.10 to 0.50m. During the high-water season, natural runoff is used to achieve this.

6. The method for pulsed ecological scheduling for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The safety constraints described in step S5 include the following six items: Ecological baseflow constraint: The outflow rate at any time period shall not be lower than the ecological baseflow; Maximum safe discharge constraint: The discharge flow rate at any time shall not exceed the smaller value between the dam's safe discharge rate and the downstream maximum allowable flow rate; Dam inlet water level constraint: During the scheduling process, the dam inlet water level is between the minimum control water level and the maximum allowable water level; Downstream water level fluctuation constraint: The rate of change of downstream water level shall not exceed the maximum allowable value; Gate opening and closing rate constraint: The rate of change of gate opening shall not exceed the upper limit of the hoist's allowable limit; Water storage capacity constraint: The net water consumption in front of the dam during the scheduling period shall not exceed the adjustable water storage capacity.

7. The method for pulsed ecological scheduling for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The gate scheduling execution described in step S6 is divided into three stages: Gradual rise phase: Gradually raise the gate to the target opening, monitor the downstream water level in real time, and suspend further opening if the water level rise exceeds the warning value; Maintenance phase: Maintain the target discharge flow rate to the design duration, focusing on monitoring changes in discharge flow rate, upstream water level, chlorophyll a concentration, and flow velocity; Gradual descent phase: After the design duration is reached, the opening is gradually restored to the basic opening. If any abnormal conditions occur during the operation, such as a sudden rise in downstream water level, gate malfunction, or sudden drop in dissolved oxygen, the operation should be immediately suspended, the target flow rate reduced, or the scheduling terminated early.

8. The method for pulsed ecological scheduling for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The scheduling effect grading evaluation criteria mentioned in step S7 are as follows: Effective: Chla decreases within 24-48 hours, HRI decreases by at least one level, algal aggregation in the field weakens, no safety anomalies are observed, and the current sequence parameters are retained as the preferred calling scheme; Partially effective: If Chla or HRI decreases but does not reach the target, or if algae show a short-term rebound, appropriately increase the pulse duration, frequency, or water level fluctuation amplitude; Invalid: Chla continued to rise, HRI did not decrease, algal aggregation at the site worsened, risk level increased and sequence type adjusted; Not suitable for execution: When there is abnormal downstream water level, water supply risk or equipment malfunction, the pulse intensity should be reduced, the scheduling duration should be shortened, the applicable conditions of this type of sequence should be restricted, and this type of scheduling sequence should be stopped if necessary.

9. The pulsed ecological scheduling method for controlling algal blooms at dams and sluices according to claim 1, characterized in that: The adaptive parameter correction in step S7 includes: The scheduling sequence parameters are corrected using an exponential smoothing method as follows: In the formula, P new The corrected scheduling parameters; P old The original scheduling parameters; P obs The appropriate parameters are derived by working backward from the scheduling results. The update coefficient is set to 0.1-0.3; P represents the pulse flow rate Q. pulse Pulse duration t pulse Water level fluctuation range dH or target water exchange ratio R target ; HRI weights are adjusted using the following formula: In the formula, The new weights are adjusted for the i-th risk factor; The original weight of the i-th risk factor; The importance of the i-th risk factor in the determination of algal bloom occurrence; It is the sum of the importance of all risk factors; Let i be the normalized importance of the i-th risk factor; Update the coefficients for the weights.

10. A pulsed ecological scheduling system for controlling algal blooms at dams and sluices, used to implement the method described in any one of claims 1-9, characterized in that, include: The data acquisition module is used to collect dam engineering and operation data, hydrological and hydrodynamic data, water quality and algae data, and meteorological and light data. The algal bloom risk index calculation module is used to calculate the chlorophyll a concentration risk factor S. C Growth rate risk factor S r Hydraulic retention risk factor S Tres Water temperature suitability S T Light suitability S I Nutrient salt risk factor S NP and insufficient flow rate S v A comprehensive algal bloom risk index (HRI) was constructed, and algal bloom risks were divided into four levels based on the HRI value: Level I low risk, Level II risk of concern, Level III early warning risk, and Level IV scheduling risk. The scheduling period identification module is used to identify the dry water retention period, the normal water maintenance period, the wet water flushing period, the high algal bloom period, and special sensitive periods. The scheduling scheme generation module is used to generate candidate gate action sequences by matching the algal bloom risk level with the scheduling time period type. It also performs safety checks and screening based on ecological base flow constraints, maximum safe discharge constraints, upstream dam water level constraints, downstream water level fluctuation constraints, gate opening and closing rate constraints, and reservoir capacity consumption constraints, and outputs an executable gate scheduling scheme. The gate control execution module is used to control the gate action according to the scheduling plan and monitor the water level, flow rate and equipment status in real time. The effect evaluation and parameter correction module is used to calculate scheduling effect indicators and adaptively correct scheduling sequence parameters, HRI weights and trigger thresholds. The early warning and anomaly handling module is used to generate early warning information when the HRI reaches level II or above, and to perform pause, flow reduction or early termination operations when abnormal operating conditions occur.

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