A method for detecting wastewater discharge of river, lake and reservoir based on acoustic Doppler

Abstract

The present application relates to wastewater discharge detection technical field, especially to a kind of river and lake reservoir water body wastewater discharge detection method based on acoustic doppler.The method includes the following steps: control unmanned ship equipped with acoustic doppler profiler to carry out continuous walk detection to target river and lake reservoir water area according to preset patrol path;Acoustic doppler profiler is used to emit sound wave and receive echo signal at different water depth position, and echo intensity data is obtained in combination with the positioning information of unmanned ship;According to echo intensity data and positioning information, echo intensity profile data is constructed;According to echo intensity profile data, the relationship between echo intensity and water depth is extracted, and echo intensity change curve is formed, and abnormal change section deviating from continuous attenuation trend is identified according to echo intensity change curve, and echo abnormal position is determined;The present application improves echo abnormal identification accuracy and wastewater influence range determination precision by wastewater discharge detection.

Description

Technical Field

[0001] This invention relates to the field of wastewater discharge detection technology, and in particular to a method for detecting wastewater discharge from rivers, lakes and reservoirs based on acoustic Doppler. Background Technology

[0002] Various factories generate large amounts of wastewater during production, which is often discharged directly into rivers, lakes, and reservoirs through concealed pipes, either untreated or inadequately treated. Because these concealed pipe outlets are typically located in deeper parts of the water or extend into the central area, traditional manual detection methods struggle to reach them, hindering effective wastewater discharge monitoring. Furthermore, manual inspections are inefficient and unable to provide comprehensive and rapid coverage of large water areas. Currently, Acoustic Doppler Current Profilers (ADCPs) are widely used in river flow monitoring and velocity profile measurement. ADCPs emit sound waves into the water and utilize the Doppler effect to measure the velocity of water at different depths, constructing a velocity profile. In recent years, research has also explored mounting ADCPs on unmanned surface vessels for mobile hydrological measurements. However, existing technologies mainly focus on measuring hydrological parameters such as flow velocity and flow rate, and have not yet addressed technical solutions for detecting wastewater discharge in water bodies using the echo intensity characteristics of ADCP. Existing technologies include methods for inverting characteristic parameters of the ocean thermocline based on acoustic signals, and real-time monitoring systems for nearshore ocean thermocline water quality. However, these technologies are primarily designed for marine environments and require the deployment of multiple sensor nodes in the water body, making them unsuitable for rapid patrol scenarios in inland water bodies such as rivers, lakes, and reservoirs. Summary of the Invention

[0003] Therefore, it is necessary to provide a method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler, in order to solve at least one of the aforementioned technical problems.

[0004] To achieve the above objectives, a method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler ultrasound is provided, comprising the following steps: Step S1: Control the unmanned vessel equipped with an acoustic Doppler profiler to conduct continuous navigation and detection of the target river, lake and reservoir water area according to the preset inspection path; use the acoustic Doppler profiler to emit sound waves and receive echo signals at different water depths, and combine the positioning information of the unmanned vessel to obtain echo intensity data. Step S2: Construct echo intensity profile data based on echo intensity data and location information; extract the relationship between echo intensity and water depth based on the echo intensity profile data to form an echo intensity variation curve; and identify abnormal variation sections that deviate from the continuous attenuation trend based on the echo intensity variation curve to determine the location of the echo anomaly. Step S3: Analyze the variation characteristics of the echo intensity change curve at the corresponding water depth based on the location of the echo anomaly, identify the abnormal propagation area formed by the continuous distribution of abnormal echoes, and determine the depth and location of the wastewater influence caused by the wastewater diffusion based on the abnormal propagation area, thus forming the wastewater discharge location result. Step S4: Based on the wastewater discharge location results, continuously correlate the abnormal propagation area to determine the wastewater discharge area, and mark it in combination with the wastewater influence depth and wastewater influence location to generate the wastewater discharge distribution results of river, lake and reservoir water bodies.

[0005] The beneficial effects of this invention are as follows: by using an unmanned vessel equipped with an acoustic Doppler profiler, it can autonomously navigate to the location of the underground pipe discharge outlet in the deep water, completely solving the technical problem that traditional manual detection methods cannot reach the wastewater discharge area.

[0006] Unlike traditional water quality sensors that sample and detect at individual points, this invention uses an acoustic Doppler profiler to continuously transmit and receive sound waves, enabling the acquisition of echo intensity data at different depths in the water body. This allows for continuous and rapid scanning of the entire water body profile, resulting in more comprehensive detection information.

[0007] The presence of wastewater discharge can be determined by utilizing the effect of a thermocline formed by the discharge on sound wave propagation. When the temperature of the wastewater is higher than that of the water body, a significant thermocline forms between the upper water layer and the lower wastewater layer. Sound waves are reflected and attenuated when passing through the thermocline, resulting in a significant distortion in the echo intensity curve. This physical principle provides a reliable scientific basis for wastewater discharge detection. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the steps involved in a method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler. Figure 2 This is a schematic diagram of the echo intensity of a river, lake, or reservoir as a function of water depth in one embodiment. Figure 3 This is a schematic diagram of the average echo intensity profile distribution of a river, lake, or reservoir in one embodiment. The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0009] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0010] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0011] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0012] To achieve the above objectives, please refer to Figures 1 to 3 A method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler includes the following steps: All specific values ​​involved in this embodiment are exemplary parameters used to clearly illustrate the technical operation process and are not the only limitation of the present invention.

[0013] Step S1: Control the unmanned vessel equipped with an acoustic Doppler profiler to conduct continuous navigation and detection of the target river, lake and reservoir water area according to the preset inspection path; use the acoustic Doppler profiler to emit sound waves and receive echo signals at different water depths, and combine the positioning information of the unmanned vessel to obtain echo intensity data. Step S2: Construct echo intensity profile data based on echo intensity data and location information; extract the relationship between echo intensity and water depth based on the echo intensity profile data to form an echo intensity variation curve; and identify abnormal variation sections that deviate from the continuous attenuation trend based on the echo intensity variation curve to determine the location of the echo anomaly. Step S3: Analyze the variation characteristics of the echo intensity change curve at the corresponding water depth based on the location of the echo anomaly, identify the abnormal propagation area formed by the continuous distribution of abnormal echoes, and determine the depth and location of the wastewater influence caused by the wastewater diffusion based on the abnormal propagation area, thus forming the wastewater discharge location result. Step S4: Based on the wastewater discharge location results, continuously correlate the abnormal propagation area to determine the wastewater discharge area, and mark it in combination with the wastewater influence depth and wastewater influence location to generate the wastewater discharge distribution results of river, lake and reservoir water bodies.

[0014] In one embodiment, an unmanned surface vessel (USV) patrol route is pre-set on an electronic map based on the target river, lake, or reservoir area. The USV automatically completes its patrol and inspection along the set route at a constant speed. During the patrol, an acoustic Doppler profiler continuously emits pulsed sound waves into the water body at a fixed sampling period. After each emission, echo signals from different water depths are received simultaneously, and the corresponding water depth sampling layers are defined according to the round-trip propagation time of the sound waves.

[0015] Because suspended particles in rivers, lakes, and reservoirs continuously scatter sound waves, and interface reflections occur at the boundaries between water layers of different densities, the echo signal obtained from a single transmission simultaneously contains both the echo scattered by suspended matter and the interface reflection echo formed by the abrupt change in water density. The system arranges the echo signals corresponding to each water depth sampling layer according to the time sequence of sound wave propagation, forming echo information covering the entire water depth direction.

[0016] Echo intensity values ​​are extracted from the echo information corresponding to each water depth location, and combined with the water depth location corresponding to each sampling layer to form echo intensity distribution information. At the same time, the unmanned surface vessel uses a satellite positioning module to obtain the current position coordinates and travel time information in real time, and synchronously associates the positioning information of the corresponding detection location with the echo intensity distribution information to form echo intensity data corresponding to each detection location.

[0017] Following the positioning sequence of each detection location during the continuous navigation of the unmanned surface vessel (USV), the echo intensity data acquired at the corresponding detection locations are arranged, and continuous echo intensity profile data is constructed by combining the echo intensity values ​​corresponding to each water depth. Subsequently, the distribution of echo intensity with water depth is extracted based on the echo intensity values ​​corresponding to different water depths at each detection location, and the echo intensities corresponding to each water depth location are connected sequentially along the water depth direction to form an echo intensity variation curve. The continuous variation state of the echo intensity variation curve along the water depth direction is analyzed. When the echo intensity maintains a continuous attenuation, it is determined that the sound wave propagation of the corresponding water layer is in a normal propagation state. When the echo intensity variation curve shows obvious curvature and the echo intensity below the interface continues to decrease significantly, the difference in echo intensity variation between the upper and lower water layers at the curvature location is analyzed to identify the thermocline interface formed by the temperature difference between the upper and lower water layers. Based on the abnormal attenuation characteristics of the echo intensity caused by interface reflection, the abnormal change segment is determined. The turning point where the echo intensity changes from continuous attenuation to abnormal attenuation in the abnormal change segment is taken as the echo anomaly location.

[0018] Using the echo anomaly locations corresponding to each detection point as the starting point for analysis, echo intensity variation curves near the anomaly locations are extracted, and the extension and variation of the abnormal attenuation segment in the water depth direction and between adjacent detection points are analyzed. When multiple adjacent detection points exhibit continuous abnormal attenuation characteristics within a similar water depth range, the corresponding abnormal echo is determined to have continuous propagation characteristics, and the continuously distributed abnormal echo area is identified as the abnormal propagation zone. Subsequently, the continuous coverage range of the abnormal propagation zone along the water depth direction is statistically analyzed, and the maximum and minimum water depths corresponding to the abnormal propagation zone are determined as the wastewater influence depth range. Simultaneously, combined with the positioning coordinates of each detection point, the horizontal diffusion range corresponding to the abnormal propagation zone is determined, forming the wastewater influence location. The wastewater influence depth and the wastewater influence location are correlated to generate a wastewater discharge location result that includes the wastewater diffusion range and spatial location.

[0019] All wastewater discharge location results obtained after the unmanned surface vessel (USV) completed the entire patrol route were summarized. Based on the wastewater impact location and depth corresponding to each location result, abnormal propagation areas within the same wastewater diffusion range were merged. When multiple wastewater discharge location results are continuously close in horizontal position and the wastewater impact depth maintains continuous change, the corresponding abnormal propagation areas are identified as the same wastewater discharge area. When there is a significant discontinuity between adjacent abnormal propagation areas or a sudden change in wastewater impact depth, they are divided into different wastewater discharge areas. Subsequently, the identified wastewater discharge areas are overlaid onto the electronic map of the target rivers, lakes, and reservoirs, and the wastewater impact depth, wastewater impact range, and wastewater discharge area boundaries are marked at the corresponding locations to generate the wastewater discharge distribution results for the rivers, lakes, and reservoirs.

[0020] In another embodiment, an acoustic Doppler profiler (ADCP) is mounted on the bottom of the unmanned vessel. The ADCP includes a piezoelectric ceramic plate that continuously emits vibrating sound waves at a fixed frequency and receives echo signals reflected from suspended matter in the water.

[0021] A grid-like patrol route is planned for the lake area to be inspected. In this embodiment, the grid spacing is set to 50 meters, and the unmanned vessel's cruising speed is 1 meter per second.

[0022] The unmanned surface vessel (USV) autonomously navigates along a planned grid-like path. During navigation, the ADCP continuously emits fixed-frequency vibrational sound waves into the water and collects echo intensity data at different depths. Simultaneously, the USV's onboard GNSS positioning system records the geographical location information of each data point in real time, establishing a three-dimensional dataset of echo intensity-depth-location. The USV has an endurance of 8 hours in still water, a cruising speed of 1 m / s, a single cruising distance of 28.8 km, and a coverage area of ​​approximately 1.44 square kilometers with a grid spacing of 50 meters.

[0023] When there is no wastewater discharge in the water body, the echo intensity of the vibration sound wave decreases linearly from top to bottom. This is because as the sound wave propagates in the water, the sound energy is gradually absorbed and scattered by the water as the propagation distance increases, naturally attenuating the echo intensity. When wastewater discharge is present in the water body, since the temperature of the wastewater is usually higher than that of the water body, a significant thermocline is formed between the upper water layer and the lower wastewater layer. When the vibration sound wave passes through the thermocline, due to the abrupt change in water density and sound velocity, significant reflection and attenuation occur, resulting in a large degree of distortion in the echo intensity curve and a significant decrease in echo intensity.

[0024] The water area to be inspected is a river. The unmanned surface vessel (USV) conducts a mobile inspection along the river's flow direction, rather than a grid-like patrol. In the river inspection scenario, the USV navigates along the river's centerline or a pre-defined cross-sectional line. The Advanced Digital Conversion Process (ADCP) continuously collects echo intensity data. By analyzing the changes in the echo intensity curve, it determines whether wastewater discharge exists in the river and its location and depth.

[0025] Please refer to [link / reference needed] for further information. Figure 2 The horizontal axis represents echo intensity, and the vertical axis represents water depth. Different colored curves correspond to the echo intensity variations acquired by different beams of the acoustic Doppler profiler. In normal water layers, echo intensity continuously decreases with increasing water depth. When the sound wave propagates to the vicinity of the thermocline interface formed by wastewater diffusion, the echo intensity variation curve exhibits a significant curvature due to reduced interface reflection and transmission of sound energy, forming an abnormal attenuation section. Based on the curvature location and the abnormal attenuation section, the location of the echo anomaly can be determined. Combined with the corresponding water depth and location information, the depth and location of wastewater influence can be determined, enabling the location detection of wastewater discharge in rivers, lakes, and reservoirs.

[0026] Please refer to [link / reference needed] for further information. Figure 3 The horizontal axis represents the data set number collected along the unmanned vessel's patrol path, the vertical axis represents the water depth, and the color represents the average echo intensity at the corresponding location, with warm colors indicating higher echo intensity and cool colors indicating lower echo intensity. Based on the continuous changes in the average echo intensity profile, areas of abnormal echo intensity attenuation and their spatial extension can be identified. When wastewater discharge forms a thermocline interface, sound wave propagation is affected by interface reflection and weakened transmitted sound energy, resulting in localized abnormal changes in the echo intensity distribution. This allows for the determination of the wastewater's influence depth, location, and discharge area.

[0027] Preferably, step S1 includes: The unmanned surface vessel equipped with an acoustic Doppler profiler is controlled to continuously navigate the target river, lake, and reservoir waters along a preset patrol route, and the acoustic Doppler profiler is controlled to perform pulse sound wave emission and echo acquisition at each detection location. Based on the echo signals collected at each detection location, the system identifies the scattered echoes of suspended matter and the reflected echoes from the interface of abrupt changes in water density at different water depths, and forms the echo information for each water depth location. Echo information corresponding to the scattered echoes of suspended matter and the reflected echoes from the interface is extracted, and the correspondence between the echo information and the corresponding water depth position is established to form echo intensity distribution information; The system acquires the location information of the unmanned surface vessel's detection location and correlates the location information with the echo intensity distribution information to form echo intensity data that includes spatial location correspondence.

[0028] In one embodiment, the unmanned surface vessel (USV) continuously navigates at a constant speed along a preset patrol route in the target river, lake, or reservoir area. During the navigation, an acoustic Doppler profiler continuously emits pulsed sound waves into the water according to a preset transmission cycle. After each sound wave transmission, it simultaneously receives the echo signal returned from the corresponding detection location. The received echo signals are divided into different water depths according to the round-trip propagation time of the sound waves, enabling a single detection to obtain continuous echo information covering the entire detection water depth range.

[0029] In the echo signals acquired at various water depths, the scattered echoes formed by continuous scattering from suspended particles in the water are continuously distributed along the entire water depth direction, while the interface reflection echoes formed at the boundaries of water layers with different densities are concentrated at local water depths. Based on the distribution of the echo signals along the water depth direction, continuously distributed echoes are identified as suspended particle scattered echoes, and locally enhanced echoes with obvious reflection characteristics are identified as interface reflection echoes from water layers with abrupt changes in density. The information on suspended particle scattered echoes and interface reflection echoes is recorded according to the corresponding water depth locations, forming the echo information corresponding to each water depth location.

[0030] Based on the echo information corresponding to each water depth, the scattered echo intensity of suspended matter and the reflected echo intensity of the interface are extracted respectively. An arrangement order of the echo intensities is established according to the corresponding water depth, ensuring that each water depth corresponds to a unique echo intensity information, forming a continuous echo intensity distribution along the water depth direction. This echo intensity distribution information fully preserves the echo intensity variations and spatial distribution relationships corresponding to each water depth.

[0031] While collecting echoes at each detection location, the unmanned surface vessel (USV) simultaneously acquires the satellite positioning coordinates and travel time information for that location. Based on the detection time, it matches and associates the positioning information with the echo intensity distribution information generated at the corresponding detection location, ensuring that each set of echo intensity distribution information corresponds to a unique spatial location. This forms echo intensity data containing the detection location, water depth, and echo intensity information. Throughout the entire patrol process, the echo intensity data generated at each detection location are continuously stored according to the actual travel sequence of the USV, constituting a complete detection dataset for the target river, lake, and reservoir water area.

[0032] Preferably, the echo information for each water depth location is generated by identifying the scattered echoes of suspended matter and the reflected echoes from interfaces where water density changes abruptly, based on the echo signals collected at each detection location. Based on the echo information at each water depth, extract the basic scattered echo information formed by continuous scattering of suspended matter; Based on the basic scattered echo information, the location of abrupt changes in the scattered echo along the water depth direction is obtained, and the corresponding water density abrupt change interface is determined, and the interface reflected echo is extracted. The influence of interface reflection echo on the acoustic energy distribution of basic scattered echo information is determined, and the scattered echo intensity of basic scattered echo information below the interface of abrupt change in water density is corrected based on the influence of acoustic energy distribution to form echo information corresponding to each water depth.

[0033] In one embodiment, the echo signals acquired at each detection location are mapped to different water depths according to the round-trip propagation time of the sound wave, with each water depth corresponding to a set of echo information. Since the sound wave is continuously scattered by suspended particles during its propagation in the water, scattered echoes formed by continuous scattering by suspended matter can be detected at each water depth location. Based on the echo intensity and its continuous distribution along the water depth direction in the echo information at each water depth location, the continuously distributed scattered echoes with gradually decreasing echo intensity are extracted, and basic scattered echo information is established according to the corresponding water depth location, so that the basic scattered echo information continuously reflects the normal propagation state of the sound wave in the river, lake, and reservoir water bodies.

[0034] The echo intensity variations at different depths in the basic scattered echo information are analyzed along the water depth direction. When the echo intensity between adjacent depths changes from a continuous variation to a significant abrupt change, the corresponding depth is identified as the abrupt change location in the scattered echo. Combining the difference in echo intensity between the upper and lower layers at the abrupt change location, the water density abrupt change interface formed by the density difference between the upper and lower water layers is identified, and the interface reflected echo is extracted from the corresponding location. The interface reflected echo centrally reflects the reflected sound energy generated when sound waves propagate to the water density abrupt change interface, and its echo intensity corresponds to the degree of reflection at the interface location.

[0035] The distribution of reflected and transmitted sound energy during sound wave propagation is analyzed based on the intensity of the reflected echo from the interface and the intensity of the scattered echo corresponding to the basic scattered echo information. When the reflected echo from the interface intensifies, the transmitted sound energy propagating below the interface decreases accordingly, causing an overall reduction in the intensity of the basic scattered echo below the interface due to the abrupt change in water density. Based on the influence of the sound energy distribution corresponding to the reflected echo from the interface, the scattered echo intensity in the basic scattered echo information at each water depth below the interface is corrected so that the corrected scattered echo intensity reflects the actual propagation state after deducting the influence of interface reflection. The corrected scattered echo intensity is then reassigned to each water depth to form the echo information corresponding to each water depth.

[0036] Preferably, determining the influence of interface reflection echoes on the acoustic energy distribution of basic scattered echo information, and correcting the scattered echo intensity of basic scattered echo information below the interface of abrupt change in water density based on the acoustic energy distribution influence, includes: The change in acoustic energy after the interface intercepts the propagating acoustic energy is determined based on the intensity of the reflected echo from the interface and the intensity of the scattered echo from the base. Determine the impact of interface reflected echoes on the acoustic energy distribution of basic scattered echo information based on acoustic energy changes. Based on the influence of acoustic energy distribution, the transmitted acoustic energy passing through the interface of abrupt change in water density is determined, and the transmitted acoustic energy distribution at each water depth below the interface of abrupt change in water density is determined based on the changes in transmitted acoustic energy. Based on the transmitted acoustic energy distribution at each water depth, the intensity of the scattered echo corresponding to the basic scattered echo information below the interface of abrupt change in water density is corrected.

[0037] In one embodiment, after the interface reflection echo is extracted, the echo intensity corresponding to the interface reflection echo is compared with the scattered echo intensity corresponding to the basic scattered echo information under the same propagation path. The basic scattered echo intensity reflects the propagation state of the sound wave before reaching the interface of abrupt change in water density, while the interface reflection echo intensity reflects the degree of reflection of propagating sound energy by the interface of abrupt change in water density. Based on the intensity change relationship between the two, the change in sound energy intercepted by the interface after the sound wave propagates to the interface of abrupt change in water density is calculated. When the interface reflection echo intensity increases, it indicates that the propagating sound energy intercepted by the interface increases; when the interface reflection echo intensity decreases, it indicates that the propagating sound energy intercepted by the interface decreases, thus obtaining the change in sound energy corresponding to the interface.

[0038] Based on the analysis of acoustic energy changes, the distribution of propagating acoustic energy at the interface is determined, and the reflected acoustic energy intercepted by the interface and the propagating acoustic energy continuing to pass through the interface are correspondingly divided. When the proportion of propagating acoustic energy intercepted by the interface increases, the transmitted acoustic energy passing through the interface with a sudden change in water density decreases simultaneously; when the proportion of propagating acoustic energy intercepted by the interface decreases, the transmitted acoustic energy increases simultaneously. Based on the propagating acoustic energy distribution state corresponding to the interface location, the influence of interface reflected echoes on the acoustic energy distribution of the basic scattered echo information is determined.

[0039] Based on the influence of sound energy distribution, the transmitted sound energy passing through the interface of abrupt changes in water density is obtained, and the propagation variation of the transmitted sound energy at various water depths below the interface is analyzed along the sound wave propagation direction. During propagation, the transmitted sound energy is continuously affected by water absorption and scattering by suspended particles, and the transmitted sound energy at each water depth gradually decreases with propagation distance. A transmitted sound energy distribution is established according to the continuous variation of transmitted sound energy at each water depth, ensuring that each water depth below the interface corresponds to a unique transmitted sound energy.

[0040] Based on the transmitted acoustic energy distribution at each water depth, the scattered echo intensity at the corresponding water depth in the basic scattered echo information is corrected. Water depths with higher transmitted acoustic energy maintain higher scattered echo intensity, while water depths with a faster decrease in transmitted acoustic energy have lower scattered echo intensity. This ensures that the corrected scattered echo intensity is consistent with the actual propagating acoustic energy below the interface, and reconstructs the basic scattered echo information for each water depth below the interface of abrupt changes in water density.

[0041] Preferably, determining the transmitted sound energy passing through the interface of abrupt change in water density based on the influence of sound energy distribution, and determining the transmitted sound energy distribution at each water depth below the interface of abrupt change in water density based on the changes in transmitted sound energy, includes: The sound energy transmission ratio at the interface of abrupt change in water density is determined based on the influence of sound energy distribution, and the transmitted sound energy passing through the interface of abrupt change in water density is obtained based on the sound energy transmission ratio. The changes in transmitted sound energy at each water depth are obtained based on the direction of sound wave propagation, and the characteristics of the changes in transmitted sound energy are determined based on the changes in transmitted sound energy. The distribution of transmitted sound energy at each water depth below the interface of abrupt change in water density is monitored based on the continuous changes in the characteristics of transmitted sound energy along the water depth direction.

[0042] In one embodiment, the transmission state of propagating sound energy at the interface of abrupt change in water density is analyzed based on the sound energy distribution influence corresponding to the interface reflection echo. The reflected sound energy corresponding to the interface reflection echo and the propagating sound energy continuing to pass through the interface together constitute the sound energy distribution result at the interface location. The corresponding sound energy transmission ratio is determined according to the proportion of propagating sound energy intercepted at the interface to the total propagating sound energy. The sound energy transmission ratio reflects the ability of propagating sound energy to pass through the interface of abrupt change in water density. By calculating the corresponding relationship between the propagating sound energy and the sound energy transmission ratio, the transmitted sound energy passing through the interface of abrupt change in water density is obtained.

[0043] After transmitted sound energy enters the water below the interface, it continues to propagate along the direction of sound wave propagation, and is continuously affected by water absorption and scattering by suspended matter. Based on the propagation distance at each water depth, the attenuation of transmitted sound energy between adjacent water depths is obtained, and the change in transmitted sound energy at each water depth is calculated. This change in transmitted sound energy reflects the degree of attenuation between adjacent water depths and is arranged continuously along the water depth direction to form the process of transmitted sound energy change.

[0044] The continuous variation of transmitted sound energy along the water depth direction is analyzed based on the changes in transmitted sound energy at each water depth location. When the changes in transmitted sound energy between adjacent water depth locations remain continuous, the transmitted sound energy is determined to be in a stable propagation state; when the changes in transmitted sound energy show a significant increase, it is determined that there is an enhanced propagation attenuation phenomenon at the corresponding water depth location. Based on the changes in transmitted sound energy, a characteristic of transmitted sound energy variation is formed. Combined with the continuous distribution of the characteristic of transmitted sound energy variation along the water depth direction, the transmitted sound energy at each water depth location below the interface of abrupt change in water density is continuously monitored, so that each water depth location corresponds to a unique transmitted sound energy value, forming a transmitted sound energy distribution.

[0045] Preferably, step S2 includes: Based on the echo intensity data and positioning information, corresponding echo intensity profile data is constructed, and echo intensity variation information at each water depth is extracted from the echo intensity profile data. Based on the echo intensity change information, the echo intensities corresponding to each water depth position are connected in the order of water depth to form an echo intensity change curve, and the continuous attenuation trend of echo intensity along the water depth direction is determined based on the echo intensity change curve. Based on the continuous attenuation trend, the position of the change in echo intensity variation curve that deviates from the continuous attenuation trend is obtained, and the change in echo intensity before and after the change position is analyzed to determine the abnormal change section. Based on the abnormal change section, the turning point where the echo intensity change curve changes from continuous attenuation to abnormal attenuation is extracted, and combined with the water depth and location information corresponding to the abnormal change section, the location of the echo anomaly is determined.

[0046] In one embodiment, the echo intensity data acquired at each detection location is spatially registered according to the positioning information of the unmanned surface vessel (USV). The echo intensities at different water depths at the same detection location are arranged according to the actual water depth to construct corresponding echo intensity profile data. In the echo intensity profile data, each water depth location corresponds to a set of echo intensity values ​​and their spatial coordinates. Based on the echo intensity profile data, the echo intensity variation information at each water depth location is extracted, and the echo intensities corresponding to each water depth location are sequentially connected according to the order of water depth from shallow to deep to form an echo intensity variation curve. Because sound wave propagation in normal water bodies such as rivers, lakes, and reservoirs is affected by both water absorption and the increase in propagation distance, the echo intensity usually gradually decreases with increasing water depth. Therefore, the echo intensity variation curve maintains a continuous attenuation state in the normal water body area.

[0047] Continuous analysis is performed on the resulting echo intensity variation curves to calculate the echo intensity changes between adjacent water depths and identify whether the echo intensity changes in adjacent sections remain continuous and consistent. When the echo intensity changes in multiple adjacent sections maintain a continuous attenuation and a consistent attenuation state, the corresponding sections are identified as having a continuous attenuation trend. When the echo intensity variation curves locally deviate from the continuous attenuation trend, the echo intensity changes within the corresponding water depth range before and after the deviation are analyzed to obtain the change characteristics of the echo intensity change near the deviation position, from continuous attenuation to significant weakening, and the corresponding areas are identified as anomalous change sections.

[0048] By analyzing the overall change pattern of the echo intensity variation curve in the abnormal change section, the inflection point where the echo intensity variation curve changes from continuous attenuation to abnormal attenuation is extracted. Because of the temperature difference between the wastewater and the surrounding water after it is discharged into rivers, lakes, and reservoirs, a sudden change in water density occurs in local areas. When sound waves propagate to this interface, interface reflection occurs, reducing the transmitted sound energy through the interface. The echo intensity below the interface is significantly reduced, causing the echo intensity variation curve to bend and exhibit abnormal attenuation at the corresponding location. Based on the water depth corresponding to the inflection point and combined with the positioning information collected by the unmanned surface vessel, the corresponding echo anomaly location is determined as the spatial location information of the abnormal wastewater discharge area.

[0049] Preferably, the echo intensity is connected according to the water depth order based on the echo intensity change information to form an echo intensity change curve, and the continuous attenuation trend of the echo intensity along the water depth direction is determined based on the echo intensity change curve, including: Based on the echo intensity change information, the echo intensities corresponding to each water depth position are connected in order of water depth to form the echo intensity change curves corresponding to each detection position. The continuous change of echo intensity between adjacent water depths is analyzed based on the echo intensity variation curve, and the echo intensity propagation trajectory determined by the continuous change of echo intensity along the water depth direction is extracted. Based on the propagation trajectory of the echo intensity, the propagation attenuation characteristics along the water depth direction are analyzed, and the attenuation characteristics formed by continuous propagation are determined as the continuous attenuation trend of the echo intensity along the water depth direction.

[0050] In one embodiment, based on the echo intensity change information corresponding to each detection location, the echo intensities corresponding to each water depth location are sequentially connected according to the actual water depth to form an echo intensity change curve for each detection location. The echo intensity change curve uses water depth as the longitudinal reference and echo intensity as the change quantity, reflecting the continuous change in echo intensity during the propagation of sound waves along the water depth direction. Since each detection location corresponds to an independent echo intensity change curve, the echo intensity change curves formed at different detection locations can respectively reflect the sound wave propagation characteristics of rivers, lakes, and reservoirs within the corresponding area.

[0051] Based on the resulting echo intensity variation curves, a continuous analysis is performed on the echo intensity variations between adjacent water depths to obtain the amplitude and direction of these variations, and to determine whether the echo intensity variations between adjacent sections remain continuous. When the echo intensity variations between multiple adjacent water depths remain continuous and without abrupt changes or discontinuities, the corresponding sections are sequentially connected along the water depth direction to extract the continuous propagation path of the sound wave in the river, lake, or reservoir water body, forming the echo intensity propagation trajectory. The echo intensity propagation trajectory corresponds to the continuous propagation process of the sound wave after passing through water bodies of different depths, and it can reflect the attenuation state of the sound wave energy along the water depth direction.

[0052] Based on the echo intensity propagation trajectory, the changes in echo intensity along each propagation segment along the water depth direction are analyzed to obtain the attenuation characteristics of the echo intensity within each propagation segment, and to compare whether the attenuation changes between adjacent propagation segments remain continuous and consistent. When multiple propagation segments maintain continuous attenuation, and there are no obvious abrupt changes in the attenuation changes between adjacent propagation segments, the continuous attenuation characteristics of the corresponding propagation segments are determined as the continuous attenuation trend of echo intensity along the water depth direction. When the propagation trajectory passes through the normal water body area of ​​rivers, lakes, and reservoirs, the sound wave propagation is mainly affected by water absorption and the increase in propagation distance, and the echo intensity maintains a gradual and continuous decrease along the water depth direction, thus forming a stable continuous attenuation trend. When the propagation trajectory passes near the wastewater diffusion area, the sound wave propagation is affected by the interface of abrupt changes in water density, and the echo intensity propagation trajectory will deviate from the continuous attenuation trend, with abnormal attenuation changes appearing at the corresponding locations.

[0053] Preferably, the analysis of the propagation attenuation characteristics along the water depth direction based on the echo intensity propagation trajectory, and the determination of the attenuation characteristics formed by continuous propagation as a continuous attenuation trend of echo intensity along the water depth direction, includes: Based on the echo intensity propagation trajectory, the echo intensity variation value corresponding to adjacent water depth positions is obtained along the water depth direction, and the local attenuation state corresponding to each propagation segment is determined based on the echo intensity variation value between adjacent water depth positions. Based on the local attenuation state corresponding to each propagation segment, the attenuation continuity of adjacent propagation segments is analyzed along the direction of sound wave propagation in rivers, lakes and reservoirs, and the attenuation characteristics of echo intensity propagation are formed based on the attenuation continuity. Based on the echo intensity propagation attenuation characteristics, continuous propagation attenuation characteristics are extracted, and the attenuation characteristics formed by continuous propagation are determined as the continuous attenuation trend of echo intensity along the water depth direction.

[0054] In one embodiment, the echo intensity corresponding to adjacent water depth positions is extracted along the water depth direction based on the echo intensity propagation trajectory, and the change in echo intensity between adjacent water depth positions is calculated. Based on the change in echo intensity, the attenuation degree of the echo intensity within the corresponding water layer is analyzed. Adjacent water depth segments with similar attenuation characteristics are divided into the same propagation segment, and the corresponding local attenuation state is determined according to the attenuation degree of the echo intensity within each propagation segment. The local attenuation state reflects the change in the propagation energy of the sound wave within the corresponding water layer.

[0055] Based on the local attenuation state corresponding to each propagation segment, the attenuation changes between adjacent propagation segments are analyzed along the direction of sound wave propagation in rivers, lakes, and reservoirs. When the local attenuation state between adjacent propagation segments remains continuously changing without significant abrupt changes in attenuation, the corresponding propagation segment is determined to have attenuation continuity; when the local attenuation state changes significantly, the attenuation continuity at the corresponding location is determined to have changed. The distribution of attenuation continuity between propagation segments forms the echo intensity propagation attenuation characteristics.

[0056] Based on the echo intensity propagation attenuation characteristics, propagation segments maintaining continuous attenuation are extracted to obtain the attenuation characteristics formed by continuous propagation. When the continuous attenuation characteristics remain consistent along the water depth direction, it is determined as a continuous attenuation trend of echo intensity along the water depth direction. When wastewater is discharged into rivers, lakes, and reservoirs, a thermocline interface is formed between the wastewater and the surrounding water. When sound waves propagate to the thermocline interface, interface reflection occurs, reducing the transmitted sound energy and causing changes in the attenuation continuity of local propagation segments. The echo intensity propagation attenuation characteristics deviate from the continuous attenuation trend, forming abnormal attenuation at the corresponding water depth location. The corresponding location is the water depth range where the abnormal propagation area is located.

[0057] Preferably, the location of the deviation from the continuous attenuation trend in the echo intensity variation curve is obtained based on the continuous attenuation trend, and the change in echo intensity before and after the change location is analyzed to determine the abnormal change segment, including: Based on the continuous attenuation trend, the position of the change in echo intensity variation curve that deviates from the continuous attenuation trend is obtained, and the curvature position in the echo intensity variation curve is identified based on the continuous change in echo intensity before and after the change position. Based on the location of the tortuosity, the attenuation changes of the water body before and after different water depths in rivers, lakes and reservoirs are analyzed, and the thermocline interface formed by the density change of the water body is identified according to the attenuation change characteristics corresponding to the location of the tortuosity, so as to determine the abnormal propagation section. Based on the analysis of the abnormal propagation section, the change in echo intensity before and after the sound wave passes through the thermocline interface is determined, the abnormal attenuation section of echo intensity caused by interface reflection is identified, and the bending position and abnormal attenuation section are identified as abnormal change sections.

[0058] In one embodiment, based on the continuous attenuation trend of echo intensity along the water depth direction, the echo intensity variation curve is analyzed layer by layer, comparing the difference between the echo intensity variation at each water depth location and the continuous attenuation trend. When the echo intensity variation curve deviates from the continuous attenuation trend within a local water depth range, the corresponding change location is extracted, and the echo intensity variation at adjacent water depth locations before and after the change location is analyzed. Based on the direction and amplitude of the echo intensity change, the location where the echo intensity variation curve changes from continuous attenuation to rapid attenuation is identified, and this location is determined as the curvature change location.

[0059] Based on the location of the tortuosity change, the attenuation state of the echo intensity in the upper and lower layers of the water body at the corresponding water depth is analyzed, and the changes in echo intensity above and below the tortuosity change position are compared. When the echo intensity above the tortuosity change position remains continuously attenuated, while the echo intensity in the lower water layer decreases rapidly, the characteristics of the attenuation abrupt change at the corresponding position are analyzed. After wastewater is discharged into the water body of the river, lake, or reservoir, a density abrupt change interface is formed between the wastewater and the surrounding water body. The propagation medium near the interface changes, and the echo intensity change curve shows abrupt attenuation at the corresponding position. Based on the characteristics of the attenuation abrupt change, the thermocline interface formed by the density abrupt change is identified, and the corresponding water depth range is determined as the anomalous propagation section.

[0060] The changes in echo intensity before and after the sound wave crosses the thermocline interface are analyzed based on the abnormal propagation sections, and the differences in echo intensity changes on the upper and lower sides of the interface are compared. When the sound wave propagates to the thermocline interface, some of the sound energy is reflected at the interface, reducing the transmitted sound energy. This causes the echo intensity below the interface to continuously deviate from the continuous attenuation trend, forming abnormal attenuation. The abnormal attenuation sections caused by interface reflection are identified based on the characteristics of the echo intensity changes before and after the interface. Combining the spatial correspondence between the curvature location and the abnormal attenuation sections, the curvature location and the abnormal attenuation sections are jointly determined as the abnormal change sections.

[0061] Preferably, the attenuation changes of river, lake, and reservoir water bodies before and after different water depths are analyzed based on the tortuosity location, and the thermocline interface formed by the density abrupt change in water body is identified based on the attenuation abrupt change characteristics corresponding to the tortuosity location, thus determining the abnormal propagation section, including: Based on the location of the curvature change, the echo intensity change curve is obtained before and after the corresponding water depth position. The corresponding abrupt attenuation change position is determined according to the change characteristics of the echo intensity change from continuous attenuation to significant attenuation. Based on the location of the attenuation abrupt change, the difference in sound wave propagation between the upper and lower water layers at the corresponding water depth is analyzed, and the interface reflection characteristics formed by the difference in sound wave propagation are used to identify the thermocline interface formed by the density abrupt change in water, and determine the corresponding interface propagation section. Based on the analysis of the changes in transmitted acoustic energy after the sound wave passes through the thermocline interface in the interface propagation section, and according to the abnormal attenuation characteristics of the continuous attenuation of the echo intensity below the interface caused by the decrease in transmitted acoustic energy, the interface propagation section is identified as the abnormal propagation section.

[0062] In one embodiment, based on the bend position identified in the echo intensity variation curve, the echo intensity changes at the corresponding water depth and its adjacent depths above and below the bend position are extracted, and the amplitude and attenuation degree of the echo intensity change before and after the bend position are analyzed. When the echo intensity corresponding to the water layer above the bend position maintains continuous attenuation, while the echo intensity corresponding to the water layer below the bend position shows a significant weakening, the echo intensity changes at multiple adjacent water depths before and after the bend position are continuously compared to obtain the change process of the echo intensity from continuous attenuation to significant attenuation. The corresponding attenuation abrupt change position is determined based on the position where the amplitude of the echo intensity change significantly increases. The attenuation abrupt change position corresponds to the water depth position where the echo intensity change state changes significantly, reflecting the position where the propagation medium changes during sound wave propagation.

[0063] Based on the location of attenuation abrupt changes, the differences in sound wave propagation between the upper and lower water layers at corresponding depths are analyzed. The changes in echo intensity and transmitted sound energy between the water layers above and below the attenuation abrupt change are compared. When a significant propagation difference exists between the upper and lower water layers, it indicates a change in the propagation medium during sound wave propagation. Combining the characteristics of the abrupt change in echo intensity near the attenuation abrupt change location, the interface reflection formed when the sound wave propagates to the corresponding water layer is analyzed. When interface reflection increases and the echo intensity below the interface decreases synchronously, it is determined that a thermocline interface formed by a change in water density exists at the corresponding water depth. After wastewater is discharged into rivers, lakes, and reservoirs, the wastewater temperature is higher than the surrounding water. A thermocline interface with a temperature gradient is formed at the junction of the wastewater and the surrounding water. When sound waves propagate to this interface, due to changes in the acoustic characteristics of the upper and lower water layers, some sound energy is reflected at the interface, reducing the sound energy passing through the interface and creating significantly different propagation states above and below the interface. Based on the distribution range of the thermocline interface along the water depth direction, the corresponding interface propagation section is determined.

[0064] Based on the analysis of the propagation section of the interface, the changes in transmitted acoustic energy after the sound wave crosses the thermocline interface are analyzed. The changes in transmitted acoustic energy at various water depths below the interface are obtained, and the attenuation of echo intensity after the reduction of transmitted acoustic energy is analyzed in conjunction with the echo intensity change curve below the interface. When the transmitted acoustic energy decreases, and multiple consecutive water depths below the interface show a continuous weakening of echo intensity, and the corresponding echo intensity change curve continuously deviates from the normal continuous attenuation trend, it is determined that the water layer below the interface has formed a continuous abnormal attenuation state. Based on the continuous distribution range of the abnormal attenuation state along the water depth direction, the corresponding interface propagation section is determined as the abnormal propagation section. The abnormal propagation section corresponds to the main area affecting sound wave propagation after wastewater enters the river, lake, or reservoir water body. Its starting position corresponds to the thermocline interface, and its ending position corresponds to the position where the transmitted acoustic energy returns to stability or the echo intensity tends to continuously attenuate again.

[0065] Of particular importance, step S3 includes: Based on the location of the echo anomaly along the direction of sound wave propagation, analyze the continuous distribution of echo anomalies at adjacent water depths, and determine the anomalous echo propagation zone based on the continuous distribution. The continuous coverage range of the echo anomaly along the water depth direction is obtained based on the abnormal propagation zone, and the depth of wastewater influence is determined based on the propagation boundary of the abnormal propagation zone at different water depths. Based on the abnormal propagation area, the continuous extension range of the echo anomaly in the water bodies of rivers, lakes and reservoirs is obtained, and the location of the wastewater impact is determined by combining the location information corresponding to the abnormal propagation area. Based on the depth and location of the wastewater impact, a correspondence is established between the abnormal propagation zone and the scope of the wastewater impact, and the wastewater discharge location result is formed based on the correspondence.

[0066] In one embodiment, the changes in echo anomalies at adjacent water depths are analyzed based on the location of the echo anomaly along the direction of sound wave propagation. When echo anomalies exist at adjacent water depths and remain continuously distributed, the corresponding echo anomaly locations are connected to form an abnormal echo propagation band. The abnormal propagation area is determined based on the continuous coverage of the abnormal echo propagation band. The abnormal propagation area corresponds to the water body region where the sound wave propagation state continuously changes under the influence of wastewater.

[0067] Based on the anomalous propagation zone, the continuous coverage area of ​​the echo anomaly along the water depth direction is obtained, and the propagation boundary of the anomalous propagation zone at different water depths is analyzed. When the anomalous propagation zone extends continuously from shallow water to deep water, the starting and ending water depths corresponding to the anomalous propagation zone are extracted, and the wastewater influence depth is determined based on the propagation boundary. The wastewater influence depth corresponds to the vertical range of the impact of wastewater diffusion on river, lake, and reservoir water bodies. Based on the anomalous propagation zone, the continuous extension range of the echo anomaly in river, lake, and reservoir water bodies is obtained, and the distribution of the anomalous propagation zone in horizontal space is analyzed in conjunction with the positioning information corresponding to each detection location. The spatial coverage area corresponding to the anomalous propagation zone is determined, and the location of wastewater influence is determined based on the spatial coverage area.

[0068] Based on the depth and location of wastewater impact, a correspondence is established between the abnormal propagation zone and the wastewater impact range. The spatial location and water depth range corresponding to the abnormal propagation zone are uniformly correlated to form a wastewater discharge location result. The wastewater discharge location result formed in this way can simultaneously reflect the horizontal impact range and vertical diffusion range of wastewater in river, lake and reservoir water bodies.

[0069] Of particular importance, step S4 includes: Based on the wastewater discharge location results, the spatial distribution of each wastewater-affected location is obtained, and the vertical coverage corresponding to the wastewater-affected depth is used to stratify and merge each wastewater-affected location to form the wastewater-affected range. Based on the analysis of the wastewater impact range, the spatial connectivity between adjacent wastewater impact ranges is determined, and the wastewater discharge area boundary is determined according to the spatial connectivity, thus forming the wastewater discharge area of ​​rivers, lakes and reservoirs. Based on the wastewater discharge areas of rivers, lakes, and reservoirs, the corresponding wastewater impact depth and location are extracted, and the spatial location and water depth location are marked accordingly to generate the wastewater discharge distribution results of rivers, lakes, and reservoirs.

[0070] In one embodiment, the spatial location and depth of each wastewater impact location are obtained based on the wastewater discharge location results, and the spatial distribution of each wastewater impact location in the river, lake, and reservoir water bodies is analyzed. Wastewater impact locations with adjacent spatial locations and overlapping or continuous wastewater impact depths are stratified and merged, spatially integrating the wastewater impact ranges corresponding to different water depths to form corresponding wastewater impact ranges. The wastewater impact range reflects the actual diffusion area of ​​wastewater in the river, lake, and reservoir water bodies, and its coverage includes both horizontal and vertical diffusion.

[0071] Based on the spatial connectivity analysis of adjacent wastewater impact areas, connectivity analysis is performed on areas where the spatial distance is continuous and the wastewater impact areas are in contact or partially overlapping. When multiple wastewater impact areas maintain continuous connectivity, the corresponding areas are merged into the same wastewater discharge area; when there are significant intervals between wastewater impact areas, the corresponding areas are divided into different wastewater discharge areas. Based on the spatial connectivity between each wastewater impact area, the continuously distributed locations on the periphery of the wastewater discharge area are extracted to determine the boundary of the wastewater discharge area, forming the wastewater discharge area for rivers, lakes, and reservoirs.

[0072] Based on the wastewater discharge areas in rivers, lakes, and reservoirs, the corresponding wastewater impact depth and location are extracted. These impact locations are then mapped one-to-one with their corresponding water depth ranges and labeled according to spatial location and water depth, generating wastewater discharge distribution results for rivers, lakes, and reservoirs. These results visually reflect the planar distribution location and corresponding impact depth of each wastewater discharge area within the river, lake, and reservoir water body, and distinguish the spatial boundaries between different wastewater discharge areas.

[0073] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler, characterized in that, Includes the following steps: Step S1: Control the unmanned vessel equipped with an acoustic Doppler profiler to conduct continuous navigation and detection of the target river, lake and reservoir water area according to the preset inspection path; use the acoustic Doppler profiler to emit sound waves and receive echo signals at different water depths, and combine the positioning information of the unmanned vessel to obtain echo intensity data. Step S2: Construct echo intensity profile data based on echo intensity data and location information; extract the relationship between echo intensity and water depth based on the echo intensity profile data to form an echo intensity variation curve; and identify abnormal variation sections that deviate from the continuous attenuation trend based on the echo intensity variation curve to determine the location of the echo anomaly. Step S3: Analyze the variation characteristics of the echo intensity change curve at the corresponding water depth based on the location of the echo anomaly, identify the abnormal propagation area formed by the continuous distribution of abnormal echoes, and determine the depth and location of the wastewater influence caused by the wastewater diffusion based on the abnormal propagation area, thus forming the wastewater discharge location result. Step S4: Based on the wastewater discharge location results, continuously correlate the abnormal propagation area to determine the wastewater discharge area, and mark it in combination with the wastewater influence depth and wastewater influence location to generate the wastewater discharge distribution results of river, lake and reservoir water bodies.

2. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler as described in claim 1, characterized in that, Step S1 includes: The unmanned surface vessel equipped with an acoustic Doppler profiler is controlled to continuously navigate the target river, lake, and reservoir waters along a preset patrol route, and the acoustic Doppler profiler is controlled to perform pulse sound wave emission and echo acquisition at each detection location. Based on the echo signals collected at each detection location, the system identifies the scattered echoes of suspended matter and the reflected echoes from the interface of abrupt changes in water density at different water depths, and forms the echo information for each water depth location. Echo information corresponding to the scattered echoes of suspended matter and the reflected echoes from the interface is extracted, and the correspondence between the echo information and the corresponding water depth position is established to form echo intensity distribution information; The system acquires the location information of the unmanned surface vessel's detection location and correlates the location information with the echo intensity distribution information to form echo intensity data that includes spatial location correspondence.

3. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler as described in claim 2, characterized in that, Based on the echo signals collected at each detection location, the system identifies the scattered echoes of suspended matter and the reflected echoes from interfaces where water density changes abruptly at different depths, and generates echo information for each water depth location, including: Based on the echo information at each water depth, extract the basic scattered echo information formed by continuous scattering of suspended matter; Based on the basic scattered echo information, the location of abrupt changes in the scattered echo along the water depth direction is obtained, and the corresponding water density abrupt change interface is determined, and the interface reflected echo is extracted. The influence of interface reflection echo on the acoustic energy distribution of basic scattered echo information is determined, and the scattered echo intensity of basic scattered echo information below the interface of abrupt change in water density is corrected based on the influence of acoustic energy distribution to form echo information corresponding to each water depth.

4. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler as described in claim 3, characterized in that, The influence of interface reflected echoes on the acoustic energy distribution of basic scattered echo information was determined, and the scattered echo intensity of the basic scattered echo information below the interface of abrupt change in water density was corrected based on the influence of acoustic energy distribution. The change in acoustic energy after the interface intercepts the propagating acoustic energy is determined based on the intensity of the reflected echo from the interface and the intensity of the scattered echo from the base. Determine the impact of interface reflected echoes on the acoustic energy distribution of basic scattered echo information based on acoustic energy changes. Based on the influence of sound energy distribution, the transmitted sound energy passing through the interface of abrupt change in water density is determined, and the distribution of transmitted sound energy at each water depth below the interface of abrupt change in water density is determined based on the changes in transmitted sound energy. Based on the transmitted acoustic energy distribution at each water depth, the intensity of the scattered echo corresponding to the basic scattered echo information below the interface of abrupt change in water density is corrected.

5. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler according to claim 4, characterized in that, The transmitted acoustic energy passing through the interface of abrupt change in water density is determined based on the influence of acoustic energy distribution, and the transmitted acoustic energy distribution at various water depths below the interface of abrupt change in water density is determined based on the changes in transmitted acoustic energy, including: The sound energy transmission ratio at the interface of abrupt change in water density is determined based on the influence of sound energy distribution, and the transmitted sound energy passing through the interface of abrupt change in water density is obtained based on the sound energy transmission ratio. The changes in transmitted sound energy at each water depth are obtained based on the direction of sound wave propagation, and the characteristics of the changes in transmitted sound energy are determined based on the changes in transmitted sound energy. The distribution of transmitted sound energy at each water depth below the interface of abrupt change in water density is monitored based on the continuous changes in the characteristics of transmitted sound energy along the water depth direction.

6. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler as described in claim 1, characterized in that, Step S2 includes: Based on the echo intensity data and positioning information, corresponding echo intensity profile data is constructed, and echo intensity variation information at each water depth is extracted from the echo intensity profile data. Based on the echo intensity change information, the echo intensities corresponding to each water depth position are connected in the order of water depth to form an echo intensity change curve, and the continuous attenuation trend of echo intensity along the water depth direction is determined based on the echo intensity change curve. Based on the continuous attenuation trend, the position of the change in echo intensity variation curve that deviates from the continuous attenuation trend is obtained, and the change in echo intensity before and after the change position is analyzed to determine the abnormal change section. Based on the abnormal change section, the turning point where the echo intensity change curve changes from continuous attenuation to abnormal attenuation is extracted, and combined with the water depth and location information corresponding to the abnormal change section, the location of the echo anomaly is determined.

7. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler as described in claim 6, characterized in that, Based on the echo intensity variation information, the echo intensities corresponding to each water depth position are connected in order of water depth to form an echo intensity variation curve. The continuous attenuation trend of the echo intensity along the water depth direction is determined based on the echo intensity variation curve, including: Based on the echo intensity change information, the echo intensities corresponding to each water depth position are connected in order of water depth to form the echo intensity change curves corresponding to each detection position. The continuous change of echo intensity between adjacent water depths is analyzed based on the echo intensity variation curve, and the echo intensity propagation trajectory determined by the continuous change of echo intensity along the water depth direction is extracted. Based on the propagation trajectory of the echo intensity, the propagation attenuation characteristics along the water depth direction are analyzed, and the attenuation characteristics formed by continuous propagation are determined as the continuous attenuation trend of the echo intensity along the water depth direction.

8. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler according to claim 7, characterized in that, Based on the analysis of the echo intensity propagation trajectory, the propagation attenuation characteristics along the water depth direction are determined, and the attenuation characteristics formed by continuous propagation are identified as the continuous attenuation trend of echo intensity along the water depth direction, including: Based on the echo intensity propagation trajectory, the echo intensity variation value corresponding to adjacent water depth positions is obtained along the water depth direction, and the local attenuation state corresponding to each propagation segment is determined based on the echo intensity variation value between adjacent water depth positions. Based on the local attenuation state corresponding to each propagation segment, the attenuation continuity of adjacent propagation segments is analyzed along the direction of sound wave propagation in rivers, lakes and reservoirs, and the attenuation characteristics of echo intensity propagation are formed based on the attenuation continuity. Based on the echo intensity propagation attenuation characteristics, continuous propagation attenuation characteristics are extracted, and the attenuation characteristics formed by continuous propagation are determined as the continuous attenuation trend of echo intensity along the water depth direction.

9. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler as described in claim 6, characterized in that, Based on the continuous attenuation trend, the locations of deviations from the continuous attenuation trend in the echo intensity variation curve are obtained, and the changes in echo intensity before and after the change locations are analyzed to determine the abnormal variation segments, including: Based on the continuous attenuation trend, the position of the change in echo intensity variation curve that deviates from the continuous attenuation trend is obtained, and the curvature position in the echo intensity variation curve is identified based on the continuous change in echo intensity before and after the change position. Based on the location of the tortuosity, the attenuation changes of the water body before and after different water depths in rivers, lakes and reservoirs are analyzed, and the thermocline interface formed by the density change of the water body is identified according to the attenuation change characteristics corresponding to the location of the tortuosity, so as to determine the abnormal propagation section. Based on the analysis of the abnormal propagation section, the change in echo intensity before and after the sound wave passes through the thermocline interface is determined, the abnormal attenuation section of echo intensity caused by interface reflection is identified, and the bending position and abnormal attenuation section are identified as abnormal change sections.

10. The method for detecting wastewater discharge from rivers, lakes, and reservoirs based on acoustic Doppler according to claim 9, characterized in that, Based on the analysis of the tortuosity location, the attenuation changes of water bodies at different depths in rivers, lakes, and reservoirs are analyzed. Furthermore, based on the abrupt attenuation characteristics corresponding to the tortuosity location, the thermocline interface formed by the abrupt change in water density is identified, and the abnormal propagation sections are determined to include: Based on the location of the curvature change, the echo intensity change curve is obtained before and after the corresponding water depth position. The corresponding abrupt attenuation change position is determined according to the change characteristics of the echo intensity change from continuous attenuation to significant attenuation. Based on the location of the attenuation abrupt change, the difference in sound wave propagation between the upper and lower water layers at the corresponding water depth is analyzed, and the interface reflection characteristics formed by the difference in sound wave propagation are used to identify the thermocline interface formed by the density abrupt change in water, and determine the corresponding interface propagation section. Based on the analysis of the changes in transmitted acoustic energy after the sound wave passes through the thermocline interface in the interface propagation section, and according to the abnormal attenuation characteristics of the continuous attenuation of the echo intensity below the interface caused by the decrease in transmitted acoustic energy, the interface propagation section is identified as the abnormal propagation section.

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