A method for testing the relationship between pollutant input and water quality of a watershed control unit

Abstract

The application discloses a watershed control unit pollutant input and water quality relationship test method, belongs to the technical field of environmental test, and mainly comprises the following steps: obtaining water quality information, setting a communication pool, setting a sampling time and analyzing pollutants.The application has the beneficial effects that a method for measuring and calculating water quality changes in a cross area is provided under the condition that the regional boundary and the control section boundary cannot be isolated at the same time when the control unit is divided; a method for using a communication water storage pool device to carry out time sequence sampling of water quality is provided; a communication water storage pool device is provided; and the method provided by the application solves the time lag problem of measuring water quality by using a water storage pool; and the method can be used for evaluating whether a complex confluence tributary is polluted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental test, and particularly relates to a test method for the relationship between pollutant input and water quality by establishing a water quality conceptual model device of a control unit of a watershed. BACKGROUND

[0002] The division of a control unit of a watershed water pollution prevention and control is an important content of preparing a watershed water pollution prevention and control plan in China, and the purpose is to divide a complex watershed into several units which are independent of each other and are connected with each other, so as to facilitate systematic management and implement the strategic intention of watershed water quality target management. Through the division of the control unit, the control requirements of the watershed water quality target management can be deepened and implemented, and the control indexes can be decomposed, which reflects the hierarchical control of the watershed water quality target management, and the watershed water quality target management is implemented in the unit control (Wang Dong et al., 2012; Lei Kun et al., 2013).

[0003] At present, the control unit is widely used in water environment planning and water environment management in China, and is related to watershed water pollution control, water ecological zoning, watershed water environment management, water function area and water body standard reaching scheme, etc. Its division method is slightly different in different research fields. In the watershed water pollution control, the watershed area and water quality target are used for division; in the water ecological function zoning, the water ecological zone is divided based on the differences and similarities of environmental elements, water ecological system characteristics and ecological service functions in different regions (Deng Fujian et al., 2016) ; in the three lines and one single of the watershed water environment management, the basic environmental control unit is divided based on the township street and industrial agglomeration area according to the ecological protection red line, the seriously over-standard pollution area, the main pollution transport source area of the regional watershed, the sensitive area of the environmental receptor, the population gathering area and the high-pollution fuel forbidden area (Li Wangfeng et al., 2018) ; in the water function area, the basic environmental control unit is divided based on the township street and industrial agglomeration area according to the distribution of pollution sources in the research area and the hydrological characteristics of the river, combined with the water function area zoning and the local administrative zoning; in the water body standard reaching scheme, the basic environmental control unit is divided based on the township street and industrial agglomeration area according to the watershed area and the administrative zoning (Zhu Guoyu, 2003).

[0004] Although the division methods of the control unit are slightly different in different research fields, they all have the common ground of being based on the watershed, the administrative zoning and the pollution source, and taking into account the environmental elements and management characteristics of China for division.

[0005] The concept of control unit originated from the water quality planning in the United States. It aims at problem water bodies, and is based on water ecological function zoning. The whole watershed is divided into control units of different scales, and control measures are proposed for the concentration and total amount of pollution discharge in the unit to restore and maintain the water environmental quality of the watershed. The management of watershed water environmental protection based on water ecological zones is conducive to the maintenance of the ecological system within the watershed, but as a management method of the basic spatial unit of watershed water pollution control, it is not common. The control unit of the TMDL plan of watershed water pollution control in the United States is divided according to the runoff characteristics of the watershed, and the hydrological response unit watershed (watershed) and sub-watershed (subwatershed) divided by the United States Geological Survey are mostly used (USEPA., 1999).

[0006] According to different management modes and division basis, control units can be mainly divided into three categories: control units based on hydrological units, control units based on water ecological zones, and control units based on administrative regions. Among them, the control unit based on hydrological unit usually reflects the surface and subsurface runoff above a certain measurement point, and the runoff condition determines the characteristics of the watershed, such as the movement of point source and non-point source pollution in the watershed, which is related to runoff, so it is suitable for the research of watershed water pollution control. Based on water ecological zone, the water environmental protection target of different water ecological zones is determined by water ecological zoning from the perspective of regional ecological carrying capacity in the watershed. The control unit based on administrative region is based on administrative division, which is conducive to the water quality management of the national level and local governments at all levels, so the administrative unit has been the basic unit of domestic water quality management (Jin Taotao, 2011).

[0007] The purpose of control unit division is to define the spatial range that affects the water quality of the control section, and to clarify the spatial boundary of the response relationship analysis between human activities such as pollution discharge and the water quality of the control section, so as to further strengthen the problem-oriented, target-oriented and measure implementation of water pollution control and water ecological protection. The complex water ecological and environmental problems are decomposed and implemented to the control unit, which effectively promotes the water ecological and environmental protection work.

[0008] The application control unit analyzes the spatial range of the control section, and clearly defines the key protection target and boundary range in space. In time, it can distinguish the differences in the emission time characteristics of each control unit, and according to their characteristics, different seasonal control conditions are adopted to obtain better environmental and economic benefits. At the same time, the division of the control unit can be carried out in the same city or in a certain river basin range, according to the water ecological environment target requirements and specific problems, different control indicators are selected to avoid the one-size-fits-all ecological environment management measures. In addition, the division of the control unit can make a comprehensive analysis of the characteristics of each control unit from the perspective of the river basin, and comprehensively consider the water ecological environment target, water quality status, technical feasibility, social and economic development level, investment benefit ratio, etc. of different control units, and sort the priority control order of the control unit, determine the priority control unit as the focus of water pollution control and water ecological protection in a certain period, so as to carry out water ecological environment protection work in stages in a planned and step-by-step manner.

[0009] The division principles of the control unit generally include the following contents:

[0010] a) Basin and catchment area boundary isolation principle

[0011] This principle takes the basin or catchment area boundary as the isolation boundary between control units, and the pollution emissions and other human activities within the control unit do not exchange with other control units, and the pollutants in the receiving water body all come from the control unit. If this principle fails, there are non-point source cross-border, and the pollutants of the land control unit are transported to other areas through pipelines or other ways, or the pollutants of other control units are transported to this area. For these situations, they should be considered in the control unit division process.

[0012] b) Clean boundary isolation principle

[0013] The so-called clean boundary refers to determining the river section with higher river water function and higher water quality protection target according to the characteristics of the basin water body function (water ecological function, water function area), such as the natural protection area with water quality requirement of class I, drinking water source area with water quality requirement of class II or class III, etc. The lower boundary of these river sections is the clean boundary. The water area boundary divided by the clean boundary as the control unit can meet the water quality target determined by the section on the one hand, and the function of the high-function water body; on the other hand, because the water quality target of this section is higher, it can generally meet the water quality requirements of the downstream control unit, and there will be no boundary dispute problem, which is convenient for each unit to independently manage the unit water quality target and independently carry out water pollution control planning.

[0014] c) Control section isolation principle

[0015] The adjacent control units are connected by pollution control sections. The control unit should control the pollution generated in this area and not input to other control units. The monitoring points are set up at the connection of the section to check. One control unit contains at least one control section.

[0016] d) Water body type isolation principle

[0017] The boundary of the control unit is the junction section of the river-lake, river-reservoir, and river-estuary to facilitate the connection of water environment planning schemes of different types of water bodies.

[0018] e) Regional boundary isolation principle

[0019] This principle fully considers the administrative boundaries. While giving priority to the isolation of river basins and catchment areas and the clean boundary isolation principle, the control unit division should not break the administrative boundaries as much as possible, i.e., to ensure its integrity and to ensure that the tasks and measures of the water environment planning of the control unit can be ultimately implemented in the administrative area, with clear administrative responsibility subjects, to ensure the implementation of task decomposition, project construction, supervision and management, pollution source accounting, social and economic data statistical analysis, and public participation. In principle, the control unit does not cross the provincial administrative area.

[0020] f) Other isolation principles

[0021] The principle of facilitating the simplification of pollution source management and the clear environmental quality responsibility person. For example, when dividing the control unit, the degree of convenience for pollution source management should be considered. The "river length system" or "piece length system" management mechanism is implemented in river management, with local party and government leaders as the first responsible person for river governance, maximizing the execution of governments at all levels, effectively improving water quality, and combining this management mechanism with the control unit division according to local conditions.

[0022] It is very difficult to satisfy the c) control section isolation principle and e) regional boundary isolation principle in the process of dividing the control unit while considering the distribution of the river basin. Especially in the characteristics of multiple tributaries, the transport and degradation of pollutants in the control unit, and the process of finally entering the next control unit are very complex. When complex tributaries are merged, the control section isolation and the regional boundary isolation cannot be satisfied at the same time, and environmental managers are difficult to determine the actual impact of pollution on the downstream unit through the monitoring data in the unit.

[0023] According to the basic project standard limit value of the Groundwater Environmental Quality Standard, there are 24 monitoring projects. There are clear provisions for I-V water bodies. When there is pollutant input in the basin control unit, the water quality will change. When the regional boundary and the control section boundary cannot be isolated, the pollutant may be input between the regional boundary and the control boundary, and the regional monitoring cannot complete the pollutant. Therefore, when the control section isolation and the regional boundary isolation cannot meet the requirements at the same time, a method needs to be constructed between the control section boundary and the regional boundary to trace the pollutant. SUMMARY

[0024] The present application provides a method for measuring the water quality change in the intersection area when the regional boundary and the control section boundary cannot be isolated at the same time during the division of the control unit, that is, a test method for the relationship between pollutant input and water quality in the basin control unit.

[0025] A test method for the relationship between pollutant input and water quality in the basin control unit, comprising the following prerequisites:

[0026] In the existing upstream control unit, the last control section of the upstream control unit within 50 km from the downstream control unit boundary;

[0027] In the existing downstream control unit, the most upstream control section of the downstream control unit within 50 km from the downstream control unit boundary;

[0028] There is at least one tributary inlet located between the last control section of the upstream control unit and the most upstream control section of the downstream control unit;

[0029] All tributary inlets in the upstream control unit have water quality control sections.

[0030] The tributary between the last control section of the upstream control unit and the most upstream control section of the downstream control unit belongs to a complex inflow tributary.

[0031] Since the complex inflow tributary has no control section, the downstream control unit cannot determine whether the water quality of the complex inflow tributary meets the standard.

[0032] The relationship between pollutant input and water quality in the basin control unit is obtained by the following steps:

[0033] Obtain the water quality information of the most upstream control section of the upstream control unit, the water quality information of the most downstream control section (section 1) of the upstream control unit, and the water quality information of the most upstream control section (section 2) of the downstream control unit in the system;

[0034] The connecting water storage tank Tank1 is arranged at the most downstream control section (section 1) of the upstream control unit, and the connecting water storage tank Tank2 is arranged at the most upstream control section (section 2) of the downstream control unit;

[0035] The connecting water storage tank comprises a water inlet pipe, a water inlet and outlet valve, and a tank body, and the volume of the tank body is calculated by the formula:

[0036] V=control section average flow rate S (m / s) x water inlet and outlet pipe cross-sectional area A (m 2 ) x 12h x 3600s / h

[0037] The water inlet pipe of the water inlet and outlet pipe extends upstream, and its inlet is arranged on the main flow with an upward opening. The inlet of the water inlet pipe is conical, the large opening of the cone is upward, and the diameter is not less than 1m. The ratio of the diameter of the bottom surface of the cone to the height is not greater than 1, and the diameter D of the water inlet pipe is controlled by the following formula:

[0038] D>V 1 / 3 / 6; wherein V is the volume of the connecting water storage tank;

[0039] The water outlet pipe of the water inlet and outlet pipe extends downstream, and its outlet is arranged on the main flow with a downward opening. The outlet of the water outlet pipe adopts a special water outlet.

[0040] The special water outlet comprises a main water outlet pipe, a conical diffusion pipe and an external dissipation pipe. The main water outlet pipe is externally connected to the conical diffusion pipe, and the conical diffusion pipe is externally connected to the external dissipation pipe.

[0041] The main water outlet pipe is a common circular pipe. The conical diffusion pipe is conical, and a large number of diffusion holes are formed on the conical surface. The small head of the conical diffusion pipe is welded to the outside of the main water outlet pipe, and the large head is opened downward. The external dissipation pipe is a cylindrical pipe, which is welded to the outside of the conical diffusion pipe.

[0042] The downstream water flow impacts between the external dissipation pipe and the conical diffusion pipe, passes through the diffusion holes of the conical diffusion pipe, drives the water flow from the main water outlet pipe, and accelerates the water flow exchange process of the connecting water storage tank.

[0043] The ratio of the diameters between the large head and the small head of the conical diffusion pipe is 3-5:2.

[0044] The diameter of the diffusion hole is 6-12cm.

[0045] The inventor found through repeated experiments that when the values of the diffusion pipe and the diffusion hole do not meet this requirement, the water exchange time in the water storage tank is significantly prolonged.

[0046] The minimum bend radius of the water inlet and outlet pipe in the plane arrangement is not less than 4 times the diameter of the water inlet and outlet pipe.

[0047] The inventors found in the experiment that the water storage tank of the above device can reach the water quality characteristics consistent with the main river channel within half an hour, that is, the water quality change in the water storage tank is delayed by half an hour compared with the water quality change in the main river channel.

[0048] 3) The above-mentioned communication water storage tank Tank1 and Tank2 are sampled synchronously and at the same time interval, and the sampling time interval is less than or equal to the non-flood period of the two cross sections, and the typical rainfall flood travel time (t L -30) / 2 minutes; such sampling time setting makes the present application creatively solve the coordination between the pollutant components and time;

[0049] 4) The analysis method of the pollutant input of the downstream unit is as follows:

[0050] The water quality information QC1 of the communication water storage tank UDT at time T, and the water quality information of the communication water storage tank DUT at time T+t L -30min is QC2;

[0051] When the QC2 contains substances that do not exist in the QC1, it indicates that there is a pollutant input between the two control cross sections;

[0052] When the QC1 contains substances that do not exist in the QC2, it indicates that the pollutants in the QC1 are degraded and purified along the way;

[0053] 4.4) Further, by comparing the time of each complex incoming branch to the cross section 2, the source branch of the pollutant can be determined.

[0054] The present application has the beneficial effects that:

[0055] The present application proposes a method for measuring the water quality change in the cross area when the regional boundary and the control cross section boundary cannot be isolated at the same time in the control unit division;

[0056] The present application proposes a method for sampling water quality in time sequence using a communication water storage tank device;

[0057] The present application proposes a communication water storage tank device;

[0058] The method proposed by the present application solves the time lag problem of measuring water quality by using a water storage tank;

[0059] The method proposed by the present application can be used to evaluate whether the complex incoming branch is polluted. DETAILED DESCRIPTION

[0060] Figure 1 The spatial arrangement of each cross section of the present application is shown in the schematic diagram;

[0061] Figure 2 The arrangement schematic diagram of the communication water storage tank of the present application is shown in the schematic diagram;

[0062] Figure 3 The special water outlet pipe cross section diagram of the application. DETAILED DESCRIPTION

[0063] The application will be further described in conjunction with specific embodiments, but the protection scope of the application is not limited to this. EMBODIMENT

[0064] A test method for the relationship between pollutant input and water quality of a watershed control unit, comprising the following prerequisites:

[0065] 1) In the existing upstream control unit, the last control section UK2 of the upstream control unit within 50 km from the boundary of the downstream control unit;

[0066] 2) In the existing downstream control unit, the most upstream control section DK1 of the downstream control unit within 50 km from the boundary of the downstream control unit;

[0067] 3) There is at least one tributary R2 inlet located between the last control section UK2 of the upstream control unit and the most upstream control section DK1 of the downstream control unit;

[0068] 4) All tributary inlets in the upstream control unit have water quality control sections, and the tributary R1 in the upstream control unit has a control section; the main stream is R3, the most upstream control section of the upstream control unit of the main stream is UK1, and the most downstream section of the downstream control unit of the main stream is DK2.

[0069] The above-mentioned tributary R2 between the last control section UK2 of the upstream control unit and the most upstream control section DK1 of the downstream control unit is a complex incoming tributary.

[0070] Since the complex incoming tributary R2 has no control section, the downstream control unit cannot determine whether the water quality of the complex incoming tributary R2 meets the standard.

[0071] The following steps are adopted to obtain the relationship between pollutant input and water quality of the watershed control unit:

[0072] 1) Obtain the water quality information of the most upstream control section of the upstream control unit, the water quality information of the most downstream control section UK2 of the upstream control unit, and the water quality information of the most upstream control section DK1 of the downstream control unit in the system;

[0073] 2) Set a connected water storage tank Tank1 at the most downstream control section UK2 of the upstream control unit, and set a connected water storage tank Tank2 at the most upstream control section DK1 of the downstream control unit;

[0074] 2.1) The above-mentioned communicating water storage tank 10 comprises an inlet and outlet pipe, an inlet and outlet valve, and a tank body, the volume of which is designed according to the following formula:

[0075] V = control section average flow rate S (m / s) x inlet and outlet pipe cross-sectional area A (m 2 ) x 12 (h) x 3600 (s / h)

[0076] 2.2) The above-mentioned inlet pipe 1 of the inlet and outlet pipe extends upstream, and its inlet is arranged on the main flow with its opening facing upstream. The inlet pipe inlet 2 is conical, with its large opening facing upstream and having a diameter not less than 1 m. The ratio of the diameter of the bottom surface to the height of the cone is not greater than 1. The diameter D of the inlet pipe 1 is controlled according to the following formula:

[0077] D > V 1 / 3 / 6; wherein V is the volume of the communicating water storage tank;

[0078] 2.3) The above-mentioned outlet pipe 3 of the inlet and outlet pipe extends downstream, and its outlet is arranged on the main flow with its opening facing downstream. The outlet pipe mouth 4 is a special outlet pipe mouth.

[0079] The above-mentioned special outlet pipe mouth comprises a main outlet pipe 41, a conical diffusion pipe 42, and an external dissipation pipe 43. The main outlet pipe 41 is externally connected to the conical diffusion pipe 42, and the conical diffusion pipe 42 is externally connected to the external dissipation pipe 43.

[0080] The main outlet pipe 41 is a common circular pipe. The conical diffusion pipe 42 is conical, with a large number of diffusion holes 44 on its conical surface. The small end of the conical diffusion pipe 42 is welded to the outside of the main outlet pipe 41, and the large end opens downstream. The external dissipation pipe 43 is a cylindrical pipe welded to the outside of the conical diffusion pipe 42.

[0081] The downstream water flow impacts between the external dissipation pipe 43 and the conical diffusion pipe 42, passes through the diffusion holes 44 of the conical diffusion pipe 42, and drives the water flow from the main outlet pipe 41, thereby accelerating the water flow exchange process of the communicating water storage tank.

[0082] The ratio of the diameters between the large and small ends of the conical diffusion pipe 42 is 3-5:2.

[0083] The diameter of the diffusion holes is 6-12 cm.

[0084] The inventor has found through repeated experiments that when the ratio of the diameters between the large and small ends of the diffusion pipe 42 is less than the above-mentioned value, or the diameter of the diffusion holes 44 is less than the above-mentioned value, the water body exchange time in the water storage tank will be significantly prolonged, generally more than 1 hour.

[0085] 2.4) The above-mentioned inlet and outlet pipe has a minimum bend radius not less than 4 times the diameter of the inlet and outlet pipe in plan view.

[0086] 2.5) The inventors found in the experiment that the water quality of the water storage tank can reach the same water quality characteristics as the main river channel within half an hour, that is, the water quality change in the water storage tank is delayed by half an hour compared with the water quality change in the main river channel.

[0087] 3) The above-mentioned connecting water storage tanks Tank1 and Tank2 are sampled synchronously and at the same time interval, and the sampling time interval is 10 minutes. The typical rainfall flood travel time t L = 52 minutes; t L -30 = 22 minutes, and the sampling step is 10 minutes < 22 / 2 minutes.

[0088] 4) The analysis method of the pollutant input of the downstream unit is as follows:

[0089] 4.1) The water quality information QC1 of the connecting water storage tank Tank1 at time T contains excessive coliform bacteria and does not contain aromatic hydrocarbon compounds, which indicates that at T-30 minutes, the section UK2 contains excessive coliform bacteria and does not contain aromatic hydrocarbon compounds. Tank2 is sampled at T+10 minutes, T+20 minutes, T+30 minutes, T+40 minutes, T+50 minutes, and T+60 minutes. Since the water transmission time of the two sections is 52 minutes, generally, at T+22 minutes, that is, T+52 minutes, the section DK1 has similar water quality characteristics as QC1. After T+52 minutes, that is, at T+60 minutes, the section DK1 is sampled to obtain the water quality information QC2.

[0090] 4.2) If aromatic hydrocarbon compounds are detected in QC2, it indicates that the R2 inflow contains aromatic hydrocarbon compounds.

[0091] 4.3) Due to dilution, the coliform bacteria in QC2 are not excessive, which indicates that the pollutants in QC1 are diluted and purified along the way.

[0092] 4.4) It is known that in the non-flood period, the typical rainfall flood travel time of R2 inflow to DK1 section is 35 minutes. The water quality information of DK1 at time T+50, T+40, T+30, and T+20 is found to have a peak value of aromatic hydrocarbon compounds at T+30 minutes, and the pollutant is calculated to come from the R2 inflow according to the time.

Claims

1. A method for testing the relationship between pollutant input and water quality in a catchment control unit, characterized by: The following steps are adopted to obtain the relationship between the pollutant input and water quality of the basin control unit with complex tributary confluence: 1) Obtain the water quality information of the most upstream control section of the upstream control unit, the most downstream control section of the upstream control unit, and the most upstream control section of the downstream control unit in the existing monitoring system; 2) Set a connected storage tank Tank1 at the most downstream control section of the upstream control unit and a connected storage tank Tank2 at the most upstream control section of the downstream control unit; 3) Tank 1 and Tank 2 are sampled synchronously and at the same time interval, which is not greater than (t L -30) / 2 minutes, The t L is the travel time of the two-section non-flood period typical rainfall flood; 4) The analysis method for the pollutant input of the downstream unit is as follows: 4.1) water quality information QC1 of the connected tank Tank1 at time T, water quality information QC2 of the connected tank Tank2 at time T+t L - water quality information at 30 min is QC2; 4.2) When QC2 contains a substance that does not exist in QC1, it indicates that there is a pollutant input between the two control sections; 4.3) When QC1 contains a substance that does not exist in QC2, it indicates that the pollutant in QC1 has been degraded and purified along the way; The connected storage tank Tank1, Tank2 includes an inlet and outlet pipe, an inlet and outlet valve, and a storage tank body, and the volume calculation formula of the tank body is: V = S × A × 12h × 3600s / h S is the average flow velocity of the control section, in m / s; A is the cross-sectional area of the inlet and outlet pipes, in m 2 ; The inlet pipe of the inlet and outlet pipe extends upstream, and its inlet is arranged on the main stream with an upward opening. The inlet of the inlet pipe is conical, the large opening of the cone is upward, and the diameter is not less than 1m. The ratio of the diameter of the bottom surface to the height of the cone is not greater than 1, and the diameter D of the inlet pipe is controlled by the following formula: D> V 1 / 3 / 6; wherein V is the volume of the communicating tank The outlet pipe of the inlet and outlet pipe extends downstream, and its outlet is arranged on the main stream with a downward opening. The outlet of the outlet pipe adopts a special outlet pipe; The special outlet pipe includes a main outlet pipe, a conical diffusion pipe, and an external dissipation pipe. The main outlet pipe is externally connected to the conical diffusion pipe, and the conical diffusion pipe is externally connected to the external dissipation pipe. The main outlet pipe is a common circular pipe. The conical diffusion pipe is conical, and diffusion holes are opened on its conical surface. The small head is welded to the outside of the main outlet pipe, and the large head is opened downward. The external dissipation pipe is a cylindrical pipe welded to the outside of the conical diffusion pipe, and diffusion holes are also opened on the surface of the external dissipation pipe; The ratio of the diameters between the large head and the small head of the conical diffusion pipe is 3-5:2; The diameter of the diffusion hole is 6-12cm; The complex tributary refers to: 1) In the existing upstream control unit, the last control section within 50km from the boundary of the downstream control unit has an upstream control unit; 2) In the existing downstream control unit, the most upstream control section within 50km from the boundary of the downstream control unit has a downstream control unit; 3) There is at least one tributary inlet located between the last control section of the upstream control unit and the most upstream control section of the downstream control unit; 4) All tributary inlets in the upstream control unit have water quality control sections. The above-mentioned tributary between the last control section of the upstream control unit and the most upstream control section of the downstream control unit is a complex confluence tributary.

2. The method according to claim 1, wherein: The minimum bend radius of the inlet and outlet pipe in the plane arrangement is not less than 4 times the diameter of the inlet and outlet pipe.

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