Multi-branch total nitrogen load control method for connection of rivers and lakes

Abstract

The invention discloses a multi-branch total nitrogen load control method for connection of rivers and lakes, and belongs to the field of total nitrogen load control, and the method comprises the steps: traversing the size of a time window, and respectively building a regression model of a sliding accumulated total nitrogen pollution load and a target object total nitrogen average concentration; the size of the time window when the regression model decision coefficient reaches the maximum value is selected as the optimal time window; determining a total nitrogen concentration control target of the target area; calculating a theoretical maximum allowable accumulated total nitrogen pollution load; based on the theoretical maximum allowable cumulative total nitrogen pollution load, introducing a safety margin MOS, and determining a cumulative total nitrogen pollution load control target; and according to the accumulated total nitrogen pollution load control target and the number of the rivers flowing into the target object, an optimization model is constructed to solve the total nitrogen pollution load control target distributed to each river. According to the method, the problem that an existing control mechanism lacks comprehensive consideration on pollutant migration paths and regional contribution rates is solved.

Description

Technical Field

[0001] This invention belongs to the field of total nitrogen load control, and particularly relates to a method for controlling the total nitrogen load of multiple tributaries connecting rivers and lakes. Background Technology

[0002] Managing rivers flowing into reservoirs and lakes is the first line of defense against eutrophication, playing a crucial role in blocking external pollution sources, implementing zoned management, and building a watershed governance system. Strengthening the management of rivers flowing into reservoirs can control eutrophication at its source, achieving a shift from "passive lake management" to "proactive source protection."

[0003] Current total nitrogen management in lakes and reservoirs faces three prominent problems: First, the lag and cumulative effects are ignored. Existing management methods mostly use instantaneous concentrations or fixed annual average loads, failing to fully consider the lag effects of upstream inputs on reservoir water quality and the cumulative effects of lakes and reservoirs as "reactors" on nitrogen, leading to a disconnect between management measures and water quality response. Second, differentiated standards for different zones are lacking. Current standards mainly refer to foreign benchmarks, failing to fully consider regional differences in nutrient effects caused by geography and climate. Some high-nitrogen reservoirs remain in a mesotrophic state due to physical or phosphorus limitations; forcibly applying a uniform standard can easily lead to "overprotection" or "underprotection," necessitating the establishment of differentiated management targets based on ecological zones. Traditional proportional reduction methods do not consider the spatial heterogeneity of pollutant transport efficiency in various tributaries. Summary of the Invention

[0004] In view of the above-mentioned shortcomings in the prior art, the present invention provides a method for controlling the total nitrogen load of multiple tributaries in river-lake interconnection, which solves the problem that the current control mechanism lacks a comprehensive consideration of the pollutant migration path and regional contribution rate.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention is: a method for controlling the total nitrogen load of multiple tributaries connecting rivers and lakes, comprising: Based on the water exchange cycle of the target object, the time window size is iterated through, and a regression model is established for each time window size to correlate the sliding cumulative total nitrogen pollution load with the average total nitrogen concentration of the target object. The optimal time window is selected when the coefficient of determination of the regression model reaches its maximum value. Determine the total nitrogen concentration control target for the target area; Substitute the total nitrogen concentration control target of the target area into the regression model corresponding to the optimal time window to calculate the theoretical maximum allowable cumulative total nitrogen pollution load. Based on the theoretical maximum allowable cumulative total nitrogen pollution load, a safety margin (MOS) is introduced to determine the control target for cumulative total nitrogen pollution load; Based on the cumulative total nitrogen pollution load control target and the number of rivers flowing into the target area, an optimization model is constructed to solve the total nitrogen pollution load control target allocated to each river, thereby completing the total nitrogen load control of multiple tributaries.

[0006] Furthermore, the expression for the regression model of the sliding cumulative total nitrogen pollution load and the average total nitrogen concentration of the target object is as follows:

[0007] in, The average total nitrogen concentration of the target object; The time window value is set to The corresponding regression equation; for Before the moment The sliding cumulative total nitrogen pollution load of the target object is incorporated into the daily data. For error; This is the moment corresponding to the end of the time window; The size of the time window; For window time index; For the first - The total nitrogen pollution load of the target object is incorporated into the daily data.

[0008] Furthermore, the determination of the total nitrogen concentration control target for the target area specifically includes: Determine whether the target object has a total nitrogen concentration control target. If so, use the current target directly. Otherwise, collect historical long-term monitoring data of total nitrogen concentration of the target object under the target nutrient state, and calculate the set percentile of the historical long-term monitoring data of total nitrogen concentration as the total nitrogen concentration control target.

[0009] Furthermore, when the target object does not have a total nitrogen concentration control target, the expression for the total nitrogen concentration control target is:

[0010] in, The target for total nitrogen concentration control; This is a percentile function; This is a long-term monitoring data of historical total nitrogen concentration; To set percentiles.

[0011] Furthermore, the expression for the cumulative total nitrogen pollution load control target is:

[0012] in, The target for controlling cumulative total nitrogen pollution load; This represents the theoretical maximum allowable cumulative total nitrogen pollution load. For safety margin; The regression model corresponding to the optimal time window; The target for total nitrogen concentration control.

[0013] Furthermore, the objective function of the optimization model is:

[0014] in, To minimize the total electricity consumption required to reduce total nitrogen pollution load; For the first Electricity consumption per unit of nitrogen reduction in a river; For the first Total nitrogen reduction of the river, i.e., the first The current total nitrogen pollution load of the river and its allocation to the first The difference between the total nitrogen pollution load control targets of the two rivers; The number of rivers flowing into the target object.

[0015] Furthermore, the constraints of the optimization model are:

[0016] in, For the first Total nitrogen reduction of the river, i.e., the first The current total nitrogen pollution load of the river and its allocation to the first The difference between the total nitrogen pollution load control targets of the two rivers; The number of rivers flowing into the target object; The total nitrogen reduction target is the sum of the current total nitrogen pollution load and the cumulative total nitrogen pollution load control target. The difference.

[0017] The beneficial effects of this invention are as follows: It constructs a dynamic and precise nitrogen control system considering lag-cumulative effects. Breaking through the traditional static control model based on instantaneous concentration or fixed annual average load, it identifies the hydraulic residence time and nitrogen migration and transformation characteristics of specific reservoirs through sliding window technology, quantifying the lag period of upstream input's impact on reservoir water quality. This enables nitrogen control targets to possess dynamic precision on a time scale, realizing a shift from "end-of-pipe concentration control" to "full-process load management." It establishes a differentiated standard-setting method based on historical benchmarks. A target-setting scheme centered on the historical benchmark of specific lakes and reservoirs is proposed, constructing a differentiated control standard of "one lake, one policy," providing a convenient and feasible technical path for the scientific management of physically or phosphorus-limited reservoirs. It avoids the requirement of traditional mechanistic models for numerous parameters related to topography, soil, and meteorology. Through a purely data-driven approach, it transforms the complex reservoir hydraulic and biochemical reactions into statistical response functions, greatly reducing the technical threshold and computational cost. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0020] like Figure 1 As shown, in one embodiment of the present invention, a method for controlling the total nitrogen load of multiple tributaries connecting rivers and lakes includes: Based on the water exchange cycle of the target object, the time window size is iterated through, and a regression model is established for each time window size to correlate the sliding cumulative total nitrogen pollution load with the average total nitrogen concentration of the target object. The optimal time window is selected when the coefficient of determination of the regression model reaches its maximum value. Determine the total nitrogen concentration control target for the target area; Substitute the total nitrogen concentration control target of the target area into the regression model corresponding to the optimal time window to calculate the theoretical maximum allowable cumulative total nitrogen pollution load. Based on the theoretical maximum allowable cumulative total nitrogen pollution load, a safety margin (MOS) is introduced to determine the control target for cumulative total nitrogen pollution load; Based on the cumulative total nitrogen pollution load control target and the number of rivers flowing into the target area, an optimization model is constructed to solve the total nitrogen pollution load control target allocated to each river, thereby completing the total nitrogen load control of multiple tributaries.

[0021] The regression model for the sliding cumulative total nitrogen pollution load and the average total nitrogen concentration of the target object is expressed as follows:

[0022] in, The average total nitrogen concentration of the target object; The time window value is set to The corresponding regression equation; for Before the moment The sliding cumulative total nitrogen pollution load of the target object is incorporated into the daily data. For error; This is the moment corresponding to the end of the time window; The size of the time window; For window time index; For the first - The total nitrogen pollution load of the target object is incorporated into the daily data.

[0023] In this embodiment, the sliding window technique is used to calculate the correlation between the cumulative load of total nitrogen entering the storage area and the total nitrogen concentration in the storage area at different time scales.

[0024] First, define the cumulative total nitrogen pollution load entering the lake (reservoir) over a certain period of time: .

[0025] Based on the water exchange cycle of a specific lake (reservoir), iterate through the time window. (For example, if values ​​are taken continuously over a period of 30-120 days, the step size can be gradually reduced from large to small), corresponding to each The values ​​were selected, and regression models were established for the sliding cumulative total nitrogen pollution load and the average total nitrogen concentration in the lake area (reservoir area).

[0026] The target for controlling the total nitrogen concentration in the target area is specifically defined as follows: Determine whether the target object has a total nitrogen concentration control target. If so, use the current target directly. Otherwise, collect historical long-term monitoring data of total nitrogen concentration of the target object under the target nutrient state, and calculate the set percentile of the historical long-term monitoring data of total nitrogen concentration as the total nitrogen concentration control target.

[0027] When the target object does not have a total nitrogen concentration control target, the expression for the total nitrogen concentration control target is:

[0028] in, The target for total nitrogen concentration control; This is a percentile function; This is a long-term monitoring data of historical total nitrogen concentration; To set percentiles.

[0029] In this embodiment, lakes and reservoirs with clearly defined total nitrogen concentration control targets can directly use existing targets. For lakes (reservoirs) with high nitrogen levels but not exhibiting eutrophication due to phosphorus restrictions or other factors, the historical percentile method is used to set non-degradation targets.

[0030] Collect historical long-series monitoring data of the reservoir area under the target trophic state (such as mesotrophic), and calculate the 95th percentile of the sequence as the total nitrogen concentration control target.

[0031] The expression for the cumulative total nitrogen pollution load control target is:

[0032] in, The target for controlling cumulative total nitrogen pollution load; This represents the theoretical maximum allowable cumulative total nitrogen pollution load. For safety margin; The regression model corresponding to the optimal time window; The target for total nitrogen concentration control.

[0033] The objective function of the optimization model is:

[0034] in, To minimize the total electricity consumption required to reduce total nitrogen pollution load; For the first Electricity consumption per unit of nitrogen reduction in a river; For the first Total nitrogen reduction of the river, i.e., the first The current total nitrogen pollution load of the river and its allocation to the first The difference between the total nitrogen pollution load control targets of the two rivers; The number of rivers flowing into the target object.

[0035] The constraints of the optimization model are:

[0036] in, For the first Total nitrogen reduction of the river, i.e., the first The current total nitrogen pollution load of the river and its allocation to the first The difference between the total nitrogen pollution load control targets of the two rivers; The number of rivers flowing into the target object; The total nitrogen reduction target is the sum of the current total nitrogen pollution load and the cumulative total nitrogen pollution load control target. The difference.

Claims

1. A method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes, characterized in that, include: Based on the water exchange cycle of the target object, the time window size is iterated through, and a regression model is established for each time window size to correlate the sliding cumulative total nitrogen pollution load with the average total nitrogen concentration of the target object. The optimal time window is selected when the coefficient of determination of the regression model reaches its maximum value. Determine the total nitrogen concentration control target for the target area; Substitute the total nitrogen concentration control target of the target area into the regression model corresponding to the optimal time window to calculate the theoretical maximum allowable cumulative total nitrogen pollution load. Based on the theoretical maximum allowable cumulative total nitrogen pollution load, a safety margin (MOS) is introduced to determine the control target for cumulative total nitrogen pollution load; Based on the cumulative total nitrogen pollution load control target and the number of rivers flowing into the target area, an optimization model is constructed to solve the total nitrogen pollution load control target allocated to each river, thereby completing the total nitrogen load control of multiple tributaries.

2. The method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes according to claim 1, characterized in that, The regression model for the sliding cumulative total nitrogen pollution load and the average total nitrogen concentration of the target object is expressed as follows: in, The average total nitrogen concentration of the target object; The time window value is set to The corresponding regression equation; for Before the moment The sliding cumulative total nitrogen pollution load of the target object is incorporated into the daily data. For error; This is the moment corresponding to the end of the time window; The size of the time window; For window time index; For the first - The total nitrogen pollution load of the target object is incorporated into the daily data.

3. The method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes according to claim 1, characterized in that, The target for controlling the total nitrogen concentration in the target area is specifically defined as follows: Determine whether the target object has a total nitrogen concentration control target. If so, use the current target directly. Otherwise, collect historical long-term monitoring data of total nitrogen concentration of the target object under the target nutrient state, and calculate the set percentile of the historical long-term monitoring data of total nitrogen concentration as the total nitrogen concentration control target.

4. The method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes according to claim 3, characterized in that, When the target object does not have a total nitrogen concentration control target, the expression for the total nitrogen concentration control target is: in, The target for total nitrogen concentration control; This is a percentile function; This is a long-term monitoring data of historical total nitrogen concentration; To set percentiles.

5. The method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes according to claim 1, characterized in that, The expression for the cumulative total nitrogen pollution load control target is: in, The target for controlling cumulative total nitrogen pollution load; This represents the theoretical maximum allowable cumulative total nitrogen pollution load. For safety margin; The regression model corresponding to the optimal time window; The target for total nitrogen concentration control.

6. The method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes according to claim 1, characterized in that, The objective function of the optimization model is: in, To minimize the total electricity consumption required to reduce total nitrogen pollution load; For the first Electricity consumption per unit of nitrogen reduction in a river; For the first Total nitrogen reduction of the river, i.e., the first The current total nitrogen pollution load of the river and its allocation to the first The difference between the total nitrogen pollution load control targets of the two rivers; The number of rivers flowing into the target object.

7. The method for controlling total nitrogen load in multiple tributaries connecting rivers and lakes according to claim 1, characterized in that, The constraints of the optimization model are: in, For the first Total nitrogen reduction of the river, i.e., the first The current total nitrogen pollution load of the river and its allocation to the first The difference between the total nitrogen pollution load control targets of the two rivers; The number of rivers flowing into the target object; The total nitrogen reduction target is the sum of the current total nitrogen pollution load and the cumulative total nitrogen pollution load control target. The difference.

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