Water supply pipeline leakage monitoring and risk assessment method based on InSAR technology

Abstract

The invention discloses a water supply pipeline leakage monitoring and risk assessment method based on an InSAR technology, and belongs to the technical field of satellite-borne SAR data application, and the method comprises the steps: collecting water supply pipeline vector data and related attribute information; monthly SAR image data and DEM data of an area are monitored; utilizing a PS-InSAR method to obtain the accumulated deformation quantity and deformation rate of the earth surface; calculating a water supply pipeline vector data buffer area range, and selecting an area with relatively large land subsidence to carry out water supply pipeline hidden danger investigation in combination with the earth surface deformation condition in the buffer area; and generating a gradient map in the buffer area by using the DEM, and evaluating the leakage risk grade of the water supply pipeline by taking related factors as main evaluation indexes. The method is beneficial to accurately reducing the troubleshooting and monitoring area of the water supply pipeline, reducing the time and labor cost, evaluating the leakage risk of the water supply pipeline, and enhancing the prevention of the leakage accident of the water supply pipeline.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite-borne SAR data application, relates to water supply pipeline leakage monitoring and risk assessment, and specifically relates to a comprehensive analysis method for water supply pipeline leakage monitoring and risk assessment combining PS-InSAR technology with multi-source geographic information data. Background Art

[0002] The water supply network is one of the most important infrastructures in cities and towns, but due to poor pipe materials, aging, external damage, lack of sound management and other reasons, the commonly used pipeline leakage monitoring methods based on equipment include flow method, pressure method, listening method, tracer gas method, detection radar method, etc. They are easy to operate, but require high professionalism, high equipment and personnel costs, and are not suitable for large-scale monitoring.

[0003] With the development of remote sensing technology, synthetic aperture radar interferometry (InSAR) technology has been widely used in surface deformation monitoring. It can not only monitor in all weather conditions, over a large area, and with high precision, but also has the advantages of high monitoring efficiency and short re-measurement cycle. InSAR technology has now been gradually applied in the fields of urban ground subsidence monitoring, road collapse monitoring, landslide monitoring and early warning, etc. Therefore, the present invention applies PS-InSAR monitoring technology to water supply pipeline leakage monitoring, combines water supply pipeline data with Internet of Things monitoring equipment and big data analysis, and realizes pipeline leakage risk assessment. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a water supply pipeline leakage monitoring and risk assessment method based on InSAR technology, which has the characteristics of all-day, all-weather and high efficiency, helps to accurately narrow the water supply pipeline inspection and monitoring area, reduce time and labor costs, and evaluate the water supply pipeline leakage risk, and strengthen the prevention of water supply pipeline leakage accidents.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A water supply pipeline leakage monitoring and risk assessment method based on InSAR technology, characterized in that it includes the following steps: Step 1: Obtain monthly SAR image data of the target water supply pipeline area for more than one year; Step 2, obtaining DEM data within the target water supply pipeline area; Step 3: Obtain the target water supply pipeline vector and attribute data, where the attribute data includes the pipeline material and pipeline service life; Step 4: Using the acquired SAR image data and DEM data, the PS-InSAR method is used to calculate the surface cumulative deformation and the monthly average deformation rate, where: Step 4.1, select the main image, calculate the time and space baselines of all image pairs, and select the scene with the middle time and space baselines as the main image; Step 4.2: All images are registered and cropped with respect to the main image, and then combined to generate an interference atlas, and finally a cumulative deformation map is obtained; Step 5: Analyze the cumulative deformation diagram, delineate the area with the largest cumulative deformation, monitor and investigate the pipeline section, improve the efficiency of leakage investigation, and reduce the workload; Step 6: Calculate the 100m buffer zone around the water supply pipeline as the study area; Step 7: The cumulative deformation, deformation rate, slope, ground subsidence, ground subsidence rate, pipeline material and pipeline service life within the buffer zone are used as evaluation indicators for the leakage risk level of the water supply pipeline. For calculation, the indicators of each pipeline are divided into risk levels of 1-5, where: Step 7-1, the pipe materials include metal pipes, concrete pipes, clay pipes, plastic pipes and glass fiber reinforced plastic pipes. The durability M of the pipe materials is divided into five levels according to their characteristics: first-level plastic pipes, second-level glass fiber reinforced plastic pipes, third-level metal pipes, fourth-level concrete pipes and fifth-level clay pipes; Step 7-2: Based on the service life data of pipelines, the service life Y of pipelines is classified into the following categories: level 1: less than 5 years, level 2: 5 to 10 years, level 3: 10 to 30 years, level 4: 30 to 50 years, and level 5: more than 50 years; Step 7-3, divide the accumulated ground subsidence Q within the buffer zone into 5 categories and set the risk levels: Level 1 [-5, 5) mm, Level 2 [-10, -5) or [5, 10) mm, Level 3 [-25, -10) or [10, 25) mm, Level 4 [-25, -50) or [25, 50) mm and Level 5 <-50 or >50 mm; Step 7-4, divide the obtained land subsidence rate R into 5 categories and set the risk level: level 1 <-2 mm / a, level 2 [-2,0] mm / a, level 3 [0,2) mm / a, level 4 [2,4] mm / a and level 5 >4 mm / a; Step 7-5, assign the durability M grade of the pipeline material and the Y grade of the pipeline service life to the corresponding buffer areas according to the pipelines; Step 7-6. Calculate the water supply pipeline leakage risk level N according to the four risk levels of each pipeline: N=(M+Y+Q+R) / 4. Use mapping software to map the water supply pipeline leakage risk level in the buffer zone to obtain a risk level map, which can provide a work reference for pipeline inspectors.

[0006] The generation of the cumulative deformation map comprises the following steps: (1) All images are registered with the master image; (2) Crop all data into areas with consistent range; (3) All registered images are combined with the main image in time series, and the interference phase is calculated pixel by pixel to generate a time series interference atlas. (4) Generate PS point target interferometric phase sequence based on the ground object type; (5) Generate elevation phase by combining DEM data, remove flat ground phase and terrain phase; and perform spatial baseline improvement to remove spatial baseline residual phase; (6) Calculate the time series deformation phase of the point target, convert it into a type variable, perform benchmark correction and geocoding, and generate a ground subsidence rate map and a cumulative deformation map.

[0007] The beneficial effects of the present invention are: Taking advantage of the mutual influence of pipeline damage and ground subsidence, InSAR technology is used to quickly and effectively determine the scope of possible leakage in the water supply pipeline and reduce the workload of manual investigation.

[0008] Based on the various influencing factors of the water supply pipeline itself and external factors, the water supply pipeline leakage risk level is divided. The classification results can be used as a scientific basis for the implementation of monitoring, maintenance, management and other aspects of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The present invention is an overall flow chart of water supply pipeline leak detection.

[0010] Figure 2 This is a flow chart of SAR data preprocessing in the PS-InSAR technology of the present invention.

[0011] Figure 3 It is a flow chart of the differential interferometry process in the PS-InSAR technology of the present invention.

[0012] Figure 4 The flowchart of the spatiotemporal shape estimation in the PS-InSAR technology of the present invention.

[0013] Figure 5 The figure is a flow chart of the deformation calculation in the PS-InSAR technology of the present invention.

[0014] Figure 6 Schematic diagram of risk levels according to an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0016] like Figure 1 The figure shows the overall flow chart of water supply pipeline leak detection.

[0017] There are four steps in total: Step 1: Collect water supply pipeline vector data and attribute information related to pipeline material and service life, monthly SAR image data of the monitoring area for more than one year, and DEM data of the monitoring area; Step 2: Calculate the accumulated surface deformation and deformation rate using the PS-InSAR method; Step 3: Calculate the 100-meter buffer range of the water supply pipeline vector data, and select the area with larger settlement to conduct on-site inspection of water supply pipeline hidden dangers based on the surface deformation in the buffer zone; Step 4: Use DEM to generate a slope map within the buffer zone, and use factors such as ground settlement, ground settlement rate, slope, pipeline material, and pipeline service life as the main evaluation indicators to evaluate the risk level of water supply pipeline leakage; In step 2, based on the collected SAR image data and DEM data, the PS-InSAR method is used to process and calculate the deformation. The calculation is divided into four processes: like Figure 2 As shown in the figure, the SAR image is preprocessed. The main image is selected, the time and space baselines between all image pairs are calculated, the time and space limit distribution map is obtained, and the scene with the time and space baseline in the middle is selected as the main image. Image registration, all images are registered to the main image. Interference phase calculation, the registered interference phases are combined with the main image respectively, the interference phase is calculated pixel by pixel, and the time series interference atlas is generated. PS point selection, the pixels are screened for PS point targets, and the interference phase map of PS point targets is generated.

[0018] like Figure 3 As shown in the figure, the interferogram composed of PS point targets is subjected to flat ground and terrain phase removal, and the spatial baseline is further improved to obtain the improved flat ground phase and interferogram set. The flat ground phase and terrain phase are removed, and the flat ground is calculated based on the spatial limit parameters and the earth ellipsoid parameters; the terrain phase is generated using the registered DEM, and the flat ground and terrain phases are removed from the interferogram phase to generate a differential interferogram phase map. The spatial baseline is improved, and the spatial baseline residual phase is removed to obtain the improved flat ground phase and interferogram set.

[0019] like Figure 4As shown in the figure, the linear deformation phase of the differential interference phase of the interference pattern is estimated in the time and space domains, and the residual phase is removed to obtain the time series deformation phase of each point target. Adjacent point parameter estimation, connect the PS points to form a redundant network, and solve the difference between the differential phases of adjacent points based on the connection relationship between the points. Spatial baseline residual calculation, establish a two-dimensional periodogram of the PS point target, and estimate the linear deformation rate and elevation difference between adjacent points. Nonlinear deformation phase and atmospheric phase calculation, perform spatial domain low-pass filtering and time domain high-pass filtering on the residual phase to obtain the nonlinear deformation phase. Time series deformation variable generation, add the linear deformation phase and the nonlinear deformation phase, and combine the time baseline parameters to obtain the time series deformation phase of each PS point target.

[0020] like Figure 5 As shown, the deformation phase obtained in 2-3 is converted into line-of-sight deformation and vertical deformation, and benchmark correction and geocoding are performed to generate deformation rate map and cumulative deformation map.

[0021] Step 3: Calculate the 100-meter buffer zone of the water supply pipeline vector data, and based on the ground deformation in the buffer zone, select areas with larger settlements to conduct on-site inspections of water supply pipeline hazards.

[0022] Step 4: Use DEM to generate a slope map within the buffer zone, and use factors such as ground subsidence, ground subsidence rate, slope, pipeline material and service life as evaluation indicators for the risk level of water supply pipeline leakage. For calculation, each indicator is divided into risk levels of 1-5, and the risk level of water supply pipeline leakage is divided according to the four indicators of each pipeline: Step 4-1, the pipe materials include metal pipes, concrete pipes, clay pipes, plastic pipes and glass fiber reinforced plastic pipes. The durability M of the pipe materials is divided into five levels according to their characteristics: first-level plastic pipes, second-level glass fiber reinforced plastic pipes, third-level metal pipes, fourth-level concrete pipes and fifth-level clay pipes; Step 4-2: Based on the service life data of pipelines, the service life Y of pipelines is classified into the following categories: Level 1: less than 5 years, Level 2: 5 to 10 years, Level 3: 10 to 30 years, Level 4: 30 to 50 years, and Level 5: more than 50 years; Step 4-3: Divide the accumulated ground subsidence Q within the buffer zone into five categories and set the risk levels: Level 1 [-5, 5) mm, Level 2 [-10, -5) or [5, 10) mm, Level 3 [-25, -10) or [10, 25) mm, Level 4 [-25, -50) or [25, 50) mm and Level 5 <-50 or >50 mm; Step 4-4, divide the obtained land subsidence rate R into 5 categories and set the risk level: level 1 <-2 mm / a, level 2 [-2,0] mm / a, level 3 [0,2) mm / a, level 4 [2,4] mm / a and level 5 >4 mm / a; Step 4-5, assign the durability M grade of the pipeline material and the Y grade of the pipeline service life to the corresponding buffer areas according to the pipeline; Step 4-6: Calculate the water supply pipeline leakage risk level N according to the four risk levels of each pipeline: N=(M+Y+Q+R) / 4. Use ArcGIS software to map the water supply pipeline leakage risk level in the buffer zone to obtain a risk level map to provide a reference for pipeline inspectors. Figure 6 As shown, the highest risk level is displayed in red and requires staff to focus on checking.

Claims

1. A water supply pipeline leakage monitoring and risk assessment method based on InSAR technology, characterized in that: The following steps are involved: Step 1: Obtain monthly SAR image data of the target water supply pipeline area for more than one year; Step 2, obtaining DEM data within the target water supply pipeline area; Step 3: Obtain the target water supply pipeline vector and attribute data, where the attribute data includes the pipeline material and pipeline service life; Step 4: Using the acquired SAR image data and DEM data, the PS-InSAR method is used to calculate the surface cumulative deformation and the monthly average deformation rate, where: Step 4.1, select the main image, calculate the time and space baselines of all image pairs, and select the scene with the middle time and space baselines as the main image; Step 4.2: All images are registered and cropped with respect to the main image, and then combined to generate an interference atlas, and finally a cumulative deformation map is obtained; Step 5: Analyze the cumulative deformation diagram, delineate the area with the largest cumulative deformation, monitor and investigate the pipeline section, improve the efficiency of leakage investigation, and reduce the workload; Step 6: Calculate the 100m buffer zone around the water supply pipeline as the study area; Step 7: The cumulative deformation, deformation rate, slope, ground subsidence, ground subsidence rate, pipeline material and pipeline service life within the buffer zone are used as evaluation indicators for the leakage risk level of the water supply pipeline. For calculation, the indicators of each pipeline are divided into risk levels of 1-5, where: Step 7-1, the pipe materials include metal pipes, concrete pipes, clay pipes, plastic pipes and glass fiber reinforced plastic pipes. The durability M of the pipe materials is divided into five levels according to their characteristics: first-level plastic pipes, second-level glass fiber reinforced plastic pipes, third-level metal pipes, fourth-level concrete pipes and fifth-level clay pipes; Step 7-2: Based on the service life data of pipelines, the service life Y of pipelines is classified into the following categories: level 1: less than 5 years, level 2: 5 to 10 years, level 3: 10 to 30 years, level 4: 30 to 50 years, and level 5: more than 50 years; Step 7-3, divide the accumulated ground subsidence Q within the buffer zone into 5 categories and set the risk levels: Level 1 [-5, 5) mm, Level 2 [-10, -5) or [5, 10) mm, Level 3 [-25, -10) or [10, 25) mm, Level 4 [-25, -50) or [25, 50) mm and Level 5 <-50 or >50 mm; Step 7-4, divide the obtained land subsidence rate R into 5 categories and set the risk level: level 1 <-2 mm / a, level 2 [-2,0] mm / a, level 3 [0,2) mm / a, level 4 [2,4] mm / a and level 5 >4 mm / a; Step 7-5, assign the durability M grade of the pipeline material and the Y grade of the pipeline service life to the corresponding buffer areas according to the pipelines; Step 7-6. Calculate the water supply pipeline leakage risk level N according to the four risk levels of each pipeline: N=(M+Y+Q+R) / 4. Use mapping software to map the water supply pipeline leakage risk levels in the buffer zone. Levels 1 to 5 indicate increasing leakage risks. The resulting risk level map can provide a reference for pipeline inspectors.

2. According to claim 1, a water supply pipeline leakage monitoring and risk assessment method based on InSAR technology is characterized in that: The generation of the cumulative deformation map comprises the following steps: (1) All images are registered with the master image; (2) Crop all data into areas with consistent range; (3) All registered images are combined with the main image in time series, and the interference phase is calculated pixel by pixel to generate a time series interference atlas. (4) Generate PS point target interferometric phase sequence based on the ground object type; (5) Generate elevation phase by combining DEM data, remove flat ground phase and terrain phase; and perform spatial baseline improvement to remove spatial baseline residual phase; (6) Calculate the time series deformation phase of the point target, convert it into a type variable, perform benchmark correction and geocoding, and generate a ground subsidence rate map and a cumulative deformation map.

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