A method and system for locating a water outlet of an ice lake

Abstract

The present invention discloses a method and system for locating a water outlet of an ice lake, the method comprising the following steps: obtaining grid information and elevation information of a digital elevation model; determining multiple position information of the ice lake shoreline according to the grid information; iteratively updating the elevation information for a preset number of times; determining the drainage outlet for each iteration update from the multiple position information according to the multiple position information and the elevation information after each iteration update; determining the water outlet of the ice lake according to the number of times each position information is used as a drainage outlet. The present invention optimizes the expression of the digital elevation model data and reduces the influence of outliers and noise by iteratively updating the elevation information of the digital elevation model, so the method of the present invention can accurately simulate terrain features, thereby accurately identifying the water outlet.

Description

Technical Field

[0001] The present invention relates to the technical field of ice lake data analysis, and in particular to an ice lake outlet positioning method and system. Background Art

[0002] Glacial lake outlets are key outlets for water flow and have a direct impact on the water quantity and quality of downstream ecosystems; studying the water flow at glacial lake outlets can better understand the melting rate and pattern of glaciers and the impact of these changes on global sea level rise.

[0003] The identification of glacial lake outlets can be divided into manual visual interpretation and automatic extraction methods. Most of the currently developed automatic extraction methods are based on the literal values ​​of the digital elevation model (DEM), compare the elevation values ​​of adjacent grid points, and apply certain algorithms (such as the D8 algorithm) to calculate the water flow direction at each grid point, and then identify the outlet.

[0004] However, considering the statistical characteristics of DEM, such as the distribution of elevation values, coefficient of variation, terrain complexity, etc., DEM data may contain outliers or noise caused by measurement errors, data interpolation or other reasons. These errors will directly affect the accuracy and reliability of the glacial lake outlet positioning results based on DEM data. Summary of the invention

[0005] In order to solve the above problems, the present invention discloses a method and system for locating a water outlet of an ice lake.

[0006] The present invention discloses a method for locating a water outlet of an ice lake, comprising the following steps:

[0007] Obtain the grid information and elevation information of the digital elevation model in the target area;

[0008] Determine multiple location information of the shoreline of the glacial lake according to the grid information;

[0009] Iteratively updating the elevation information a preset number of times;

[0010] Determine the drainage outlet updated in each iteration from the plurality of position information according to the plurality of position information and the elevation information updated in each iteration;

[0011] The outlet of the glacial lake is determined based on the number of times each location information is used as a drainage outlet.

[0012] Preferably, according to the plurality of position information and the elevation information after each iteration update, the drainage outlet updated in each iteration is determined from the plurality of position information, specifically:

[0013] Determine a water flow research area corresponding to each piece of position information according to the plurality of pieces of position information;

[0014] According to the water flow study area corresponding to each position information and the elevation information after each iterative update, the drainage outlet for each iterative update is determined from the multiple position information.

[0015] Preferably, the drainage outlet for each iteration update is determined from the multiple location information according to the water flow study area corresponding to each location information and the elevation information after each iteration update, specifically:

[0016] Determine overlapping position information of the grid information in the digital elevation model and each water flow study area according to the grid information and the water flow study area corresponding to each position information;

[0017] According to the elevation information after each iteration update and each overlapping position information, the drainage outlet updated in each iteration is determined from the multiple position information.

[0018] Preferably, the drainage outlet updated in each iteration is determined from the multiple location information according to the elevation information updated in each iteration and each overlapping location information, specifically:

[0019] According to the elevation information after each iteration update and each overlapping position information, the drainage area corresponding to each position information after each iteration update is determined;

[0020] According to each drainage area, the drainage outlet updated in each iteration is determined from a plurality of position information.

[0021] Preferably, according to each drainage area, the drainage outlet updated in each iteration is determined from a plurality of position information, specifically:

[0022] The location information corresponding to the largest drainage area after each iterative update is used as the drainage outlet for each iterative update.

[0023] Preferably, the water flow research area corresponding to each position information is determined according to the multiple position information, specifically:

[0024] Obtaining the center of gravity of the glacial lake and determining the corresponding axis of the water flow research area according to the center of gravity and multiple position information;

[0025] The corresponding water flow study area is determined according to the axis of each water flow study area and the preset area size information.

[0026] Preferably, the elevation information is iteratively updated a preset number of times, specifically:

[0027] Acquiring a data source of a digital elevation model and determining preset statistical parameters according to the data source;

[0028] The elevation information is iteratively updated a preset number of times according to the Monte Carlo method and the statistical parameters.

[0029] Preferably, the elevation information is iteratively updated a preset number of times according to the Monte Carlo method and the statistical parameters, specifically:

[0030] In each iterative updating process, a corresponding random matrix is ​​generated according to the Monte Carlo method and the statistical parameters;

[0031] The elevation information is iteratively updated according to the random matrix generated in each iterative update process.

[0032] Preferably, the elevation information is iteratively updated according to the random matrix generated in each iterative update process, specifically:

[0033] The random matrix generated in each iterative updating process is added to the elevation information to obtain the elevation information after each iterative updating.

[0034] The present invention also discloses a glacial lake outlet positioning system, the system comprising:

[0035] An information acquisition module is used to obtain the grid information and elevation information of the digital elevation model;

[0036] A location information determination module, used to determine multiple location information of the ice lake shoreline according to the grid information;

[0037] An iterative update module, used for iteratively updating the elevation information a preset number of times;

[0038] A drainage outlet determination module, used to determine the drainage outlet updated in each iteration from the multiple location information according to the multiple location information and the elevation information updated in each iteration;

[0039] The outlet determination module is used to determine the outlet of the ice lake according to the number of times each location information is used as a drainage outlet.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The present invention optimizes the expression of DEM data by iteratively updating the elevation information of DEM and reduces the influence of outliers and noise. Therefore, the method of the present invention can accurately simulate the terrain characteristics, thereby improving the accuracy of water outlet identification;

[0042] (2) The solution of the present invention does not require a complicated hydrological calculation process and can quickly and accurately find the outlet of the glacial lake;

[0043] (3) The present invention constructs a corresponding water flow study area for each location information of the glacial lake shoreline and obtains the drainage area of ​​each water flow study area, thereby simulating the natural process of water flowing out from various locations of the lake shoreline. Combined with the elevation information provided by the DEM data, the present invention effectively reduces the impact of data literal value errors on the results, thereby being able to more accurately determine the location of the glacial lake outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flow chart of the method of the present invention;

[0045] Figure 2 It is a structural diagram of the system of the present invention;

[0046] Figure 3 It is a schematic diagram of the water flow study area of ​​the present invention;

[0047] Figure 4 is a flow chart of step S412 of the present invention;

[0048] In the figure, 101 is the information acquisition module; 102 is the position information determination module; 103 is the iterative update module; 104 is the drainage outlet determination module; 105 is the outlet determination module; 106 is the center of gravity of the ice lake; 107 is the first position point; 108 is the axis of the water flow research area; 109 is the first fan-shaped area; 110 is the shoreline of the ice lake. DETAILED DESCRIPTION

[0049] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0050] like Figure 1 As shown, the present invention discloses a method for locating a water outlet of an ice lake, comprising the following steps:

[0051] S1. Obtain the grid information and elevation information of the DEM (digital elevation model) in the target area; the DEM (digital elevation model) is on the surface of the earth with a preset resolution, such as a grid matrix with a spacing of 30 meters, and obtains the elevation value corresponding to each grid point in the grid matrix through different measurement tools. Therefore, in this application, the grid information refers to the grid points and their spacing in the target area, and the elevation information refers to the elevation value of each grid point. The target area includes the area where the glacial lake is located, and those skilled in the art can divide it by themselves.

[0052] Considering that the area where the glacial lake is located may span multiple DEM slices, they need to be integrated into a complete file, and there are also outliers in the DEM, which need to be cleaned to be within a reasonable range. Therefore, before S1, the DEM of the target area is also integrated and cleaned.

[0053] S2. Determine multiple position information of the ice lake shoreline 110 according to the grid information; the position information includes multiple position points on the ice lake shoreline and the spacing information and relative position information therebetween. Then S2 is specifically: determine each grid point in the grid matrix according to the grid information, align the ice lake shoreline 110 with the grid of the DEM, and use the multiple grid points aligned with the shoreline 110 as multiple position points of the shoreline; the distance, arrangement and elevation value between the multiple position points are the same as those of the grid points corresponding to the DEM.

[0054] In other embodiments, the satellite photo or the aerial photo may be aligned with the DEM grid, and each grid is either the lake body or the lake shore.

[0055] S3, iteratively updating the elevation information for a preset number of times;

[0056] Preferably, S3 is specifically:

[0057] S31, obtaining a data source of a digital elevation model and determining preset statistical parameters according to the data source;

[0058] Preferably, the statistical parameters include expectation e and standard deviation d.

[0059] In one embodiment, relevant literature may be consulted, and each statistical parameter may be preset based on the data source, resolution, accuracy parameters of the DEM, and other environmental parameters of the target area. As shown in the following table, the statistical parameter values ​​in the literature "Validation of digital elevation models (DEMs) and comparison of geomorphic metrics on the southern Central Andean Plateau" are shown, where the mean value (Mean) of the deviation between the literal value and the true measured value and the standard deviation (Standard deviation) of the deviation may be used as the expected value and the standard deviation, respectively.

[0060] Table 1. Mean and standard deviation of the deviation between the literal value of the digital elevation model (DEM) and the actual measured value under different data sources and resolutions.

[0061]

[0062] Correspondingly, the statistical parameters of the digital elevation models of different data sources can also be preset by referring to other relevant documents. That is to say, the different statistical parameters in this application can be preset by those skilled in the art by referring to relevant documents or combining the common knowledge in this field, and no further description is given. Further, when the statistical parameters corresponding to the data source of the DEM cannot be obtained from the relevant documents, the statistical parameters can be manually specified.

[0063] S32. Iteratively update the elevation information a preset number of times according to the Monte Carlo method and statistical parameters.

[0064] Preferably, S32 is specifically:

[0065] S321. In each iterative updating process, a corresponding random matrix is ​​generated according to the Monte Carlo method and statistical parameters;

[0066] S322. Perform this iterative update on the elevation information according to the random matrix generated in each iterative update process.

[0067] Based on the statistical parameters (expected e and standard deviation d) obtained in step S31, a matrix N(e, d) that obeys the normal distribution is randomly generated, and the size of the matrix is ​​consistent with the DEM of the target area. Then S322 is specifically as follows:

[0068] The random matrix generated in each iterative update process is added to the elevation information to obtain the elevation information after each iterative update.

[0069] S4, determining the drainage outlet updated in each iteration from the multiple location information according to the multiple location information and the elevation information updated in each iteration;

[0070] Preferably, S4 is specifically:

[0071] S41, determining a water flow research area corresponding to each piece of position information according to the plurality of pieces of position information;

[0072] In this embodiment, the water flow research area is a fan-shaped area.

[0073] Preferably, S41 is specifically:

[0074] S411, obtaining the center of gravity of the ice lake 106 and determining the corresponding axis of the water flow research area 108 according to the center of gravity and multiple position information;

[0075] like Figure 3 As shown, in the present application, the location information includes multiple location points and the distances between adjacent location points, and the axis of each water flow research area is: the line connecting the center of gravity 106 of the ice lake and the corresponding location point.

[0076] S412, determining the corresponding water flow study area according to the axis 108 of each water flow study area and the preset area size information.

[0077] The preset area size information includes: a preset fan angle and preset fan radii m and n, wherein m is smaller than n.

[0078] In one embodiment, the preset first sector radius m and the second sector radius n may be acquired based on the preset sector radius.

[0079] like Figure 4 As shown, S412 specifically includes: determining whether the area of ​​the ice lake is less than a preset ice lake area threshold, if so, using the first sector radius m as the preset sector area radius; if not, using the second sector radius n as the preset sector area radius.

[0080] The fan-shaped area can be determined based on the radius of the fan-shaped area and the axis of the fan-shaped area.

[0081] The area of ​​the ice lake will affect the size of the fan-shaped area, and the better fan-shaped area will affect the accuracy of the final exit. Therefore, the present application obtains the area of ​​the ice lake and determines the required size of the fan-shaped area based on the area of ​​the ice lake, which is conducive to improving the accuracy of the method of the present application.

[0082] Preferably, one square kilometer is used as the preset glacial lake area threshold.

[0083] S42. Determine the drainage outlet for each iterative update from the multiple location information according to the water flow study area corresponding to each location information and the elevation information after each iterative update.

[0084] Preferably, S42 is specifically:

[0085] S421, determining overlapping position information of the grid information in the digital elevation model and each water flow study area according to the grid information and the water flow study area corresponding to each position information;

[0086] S422. Determine the drainage outlet updated in each iteration from the multiple location information according to the elevation information updated in each iteration and each overlapping location information.

[0087] Preferably, S422 is specifically:

[0088] S4221, determining the drainage area corresponding to each position information after each iterative update according to the elevation information after each iterative update and each overlapping position information;

[0089] S4222. Determine the drainage outlet for each iteration update from multiple location information according to each drainage area.

[0090] Preferably, S4222 is specifically:

[0091] The location information corresponding to the largest drainage area after each iterative update is used as the drainage outlet for each iterative update.

[0092] The present invention can simulate the shape of a typical water flow alluvial fan and use it as a comparison benchmark by constructing a fan-shaped area with the center of gravity 106 of the ice lake and the line connecting each position point of the ice lake shoreline 110 as the symmetry axis. Under the same comparison benchmark, the drainage area of ​​each position point of the ice lake shoreline 110 outside the ice lake is calculated, and their sizes are compared to obtain the drainage point updated in this iteration. Multiple drainage points are obtained through multiple Monte Carlo simulation iterations, and the drainage point with the most occurrences is used as the outlet of the ice lake. Therefore, the present invention does not require a complicated hydrological calculation process and can quickly and accurately find the outlet of the ice lake.

[0093] Taking the determination of the drainage area corresponding to the first position point 107 after a certain iterative update process as an example, step S421 and step S422 are explained.

[0094] Step S421 includes:

[0095] Step S4211, obtaining a first position point 107 and its corresponding first sector area 109 on the ice lake shoreline 110;

[0096] Step S4212, aligning the first sector area 109 with the DEM updated in this iteration, recording the DEM grid set partially or completely within the first sector area 109 as S, and calculating the area of ​​each grid in S within the first sector area 109 according to the resolution and intersection of the DEM, that is, the overlapping position information corresponding to the first position point 107 includes: the grid set S and the area of ​​each grid within the first sector area 109;

[0097] Step S422 includes:

[0098] Step S4221, creating a drainable position point set R, where the drainable position point set R only includes the first position point 107;

[0099] Step S4222: randomly select a point on the edge of the set R as the first element.

[0100] Step S4223, find a grid point adjacent to the first element within S and outside R as the second element, and if the elevation value of the second element is less than or equal to the elevation value of the first element, add the grid point corresponding to the second element to R;

[0101] Furthermore, adjacent grid points may be determined by a 4-adjacency or 8-adjacency operation of the matrix grid.

[0102] Repeat steps S4222 to S4223 until no new grid points can be added to R, and the set of drainable location points R is created;

[0103] When the set R undergoes subsequent steps and the number of elements increases, the first element is an arbitrary position point selected from the edge of the set R, which can be the first position point 107 or any element added subsequently; each point in the set R is not limited to the number of times it can be the first element)

[0104] Step S4224, obtain the area of ​​each element in the set R in the first sector area 109, and obtain the drainage area corresponding to the first position point 107.

[0105] According to the above example, the drainage area corresponding to each position point on the ice lake shoreline 110 is calculated, and the position point corresponding to the maximum drainage area is used as the drainage point for this iteration update;

[0106] Furthermore, based on a preset number of Monte Carlo simulation iteration updates, the elevation information is updated, and the location point serving as the drainage point is obtained after each iteration update.

[0107] This application calculates the drainage area of ​​each location point on the ice lake shoreline 110 in the fan-shaped area based on the elevation information generated by multiple iterative updates, and uses the location point with the largest drainage area as the outlet for each iterative update. This can more accurately simulate the flow path and accumulation area of ​​water on the surface. Each iteration is based on the updated elevation information, which makes the location of the outlet more in line with the actual situation and improves the accuracy of the outlet positioning.

[0108] S5, determining the ice lake outlet according to the number of times each location information is used as a drain outlet. S5 specifically includes: using the location information that is used as a drain outlet the most times as the ice lake outlet.

[0109] like Figure 2 As shown, the present invention also discloses a glacial lake outlet positioning system, the system comprising:

[0110] The information acquisition module 101 is used to acquire the grid information and elevation information of the digital elevation model;

[0111] A location information determination module 102, for determining a plurality of location information of the ice lake shoreline 110 according to the grid information;

[0112] Iterative update module 103, used for iteratively updating the elevation information for a preset number of times;

[0113] A drainage outlet determination module 104, for determining a drainage outlet updated in each iteration from the plurality of position information according to the plurality of position information and the elevation information updated in each iteration;

[0114] The outlet determination module 105 is used to determine the outlet of the ice lake according to the number of times each location information is used as a drainage outlet.

[0115] The system of the present invention can automatically identify the location of the water outlet, reducing the need for manual intervention. As iterations proceed, the system can intelligently adjust the location of the water outlet to adapt to changing terrain and water flow conditions.

[0116] The present application also provides a computer-readable storage medium having a program stored thereon, wherein the stored program includes a method for locating an ice lake outlet that can be loaded by a processor and processed in any one of the above-mentioned embodiments.

[0117] Compared with the prior art, the present invention has the following beneficial effects:

[0118] (1) The present invention optimizes the expression of DEM data by iteratively updating the elevation information of DEM and reduces the influence of outliers and noise. Therefore, the method of the present invention can accurately simulate the terrain characteristics, thereby improving the accuracy of water outlet identification;

[0119] (2) The solution of the present invention does not require a complicated hydrological calculation process and can quickly and accurately find the outlet of the glacial lake;

[0120] (3) The present invention constructs a corresponding water flow study area for each location information of the ice lake shoreline and obtains the drainage area of ​​each water flow study area, thereby simulating the natural process of water flowing out from various locations of the lake shoreline. Combined with the elevation information provided by the DEM data, the present invention effectively reduces the impact of data literal value errors on the results, thereby being able to more accurately determine the outlet location of the ice lake.

[0121] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for locating a water outlet of an ice lake, characterized in that: The following steps are involved: Obtain the grid information and elevation information of the digital elevation model in the target area; Determine multiple location information of the shoreline of the glacial lake according to the grid information; Iteratively updating the elevation information a preset number of times; Obtaining the center of gravity of the glacial lake and determining the corresponding axis of the water flow research area according to the center of gravity and multiple position information; Determine the corresponding water flow study area according to the axis of each water flow study area and the preset area size information; Determine overlapping position information of the grid information in the digital elevation model and each water flow study area according to the grid information and the water flow study area corresponding to each position information; According to the elevation information after each iteration update and each overlapping position information, the drainage area corresponding to each position information after each iteration update is determined; The location information corresponding to the largest drainage area after each iteration is used as the drainage outlet for each iteration update; The outlet of the glacial lake is determined based on the number of times each location information is used as a drainage outlet.

2. The method for locating an ice lake outlet according to claim 1, characterized in that: The elevation information is iteratively updated a preset number of times, specifically: Acquiring a data source of a digital elevation model and determining preset statistical parameters according to the data source; The elevation information is iteratively updated a preset number of times according to the Monte Carlo method and the statistical parameters.

3. The method for locating an ice lake outlet according to claim 2, characterized in that: The elevation information is iteratively updated for a preset number of times according to the Monte Carlo method and the statistical parameters, specifically: In each iterative updating process, a corresponding random matrix is ​​generated according to the Monte Carlo method and the statistical parameters; The elevation information is iteratively updated according to the random matrix generated in each iterative update process.

4. The method for locating an ice lake outlet according to claim 3, characterized in that: According to the random matrix generated in each iterative update process, the elevation information is iteratively updated this time, specifically: The random matrix generated in each iterative updating process is added to the elevation information to obtain the elevation information after each iterative updating.

5. A glacial lake outlet positioning system, characterized in that: The system comprises: An information acquisition module is used to obtain the grid information and elevation information of the digital elevation model; A location information determination module, used to determine multiple location information of the ice lake shoreline according to the grid information; An iterative update module, used for iteratively updating the elevation information a preset number of times; A drainage outlet determination module is used to obtain the center of gravity of the ice lake and determine the corresponding axis of the water flow study area according to the center of gravity and multiple position information; determine the corresponding water flow study area according to the axis of each water flow study area and preset area size information; determine the overlapping position information of the grid information in the digital elevation model and each water flow study area according to the grid information and the water flow study area corresponding to each position information; determine the drainage area corresponding to each position information after each iterative update according to the elevation information after each iterative update and each overlapping position information; use the position information corresponding to the largest drainage area after each iterative update as the drainage outlet for each iterative update; The outlet determination module is used to determine the outlet of the ice lake according to the number of times each location information is used as a drainage outlet.

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