An optimal slope unit extraction method and system for earthquake landslide hazard assessment

Abstract

The invention discloses an optimal slope unit extraction method and system for earthquake landslide hazard assessment, which relates to the field of geological disaster assessment, including obtaining DEM grid data of a region to be tested and circular standard deviation, minimum division area and initial runoff accumulation for slope unit division; a slope unit division method based on slope aspect uniformity to determine the slope unit division result; according to the slope unit division result, determine the shape rationality index and area rationality index of the slope units of each division sequence, and estimate the relative importance of the two, and construct a minimum loss objective function for slope unit division; according to the minimum loss objective function, determine the optimal division thresholds of circular standard deviation and initial runoff accumulation, and obtain the optimal slope unit division result of the region to be tested. The invention takes into account the influence of geometric parameters and shape parameters on the slope unit division result, thereby improving the accuracy of slope unit division.

Description

Technical Field

[0001] The invention relates to the field of geological disaster assessment, and in particular to an optimal slope unit extraction method and system for earthquake landslide hazard assessment. Background Art

[0002] Slope unit is one of the basic assessment unit types for earthquake landslide hazard assessment in strong earthquake areas. It has been widely used in geological hazard assessment of key towns at 1:10,000 and 1:50,000 scales. Slope unit usually covers a single or several slope areas from the bottom to the top of the slope, and from the valley watershed to the ridge watershed.

[0003] At present, the existing processes of dividing slope units based on hydrological analysis, curvature watershed method and terrain image method all rely on a large number of preset division parameters. The optimal division parameter threshold is determined through repeated trial and error and manual parameter adjustment to obtain the ideal slope unit.

[0004] However, the above division methods do not examine the influence of the parameters of the divided slope units on the division results, resulting in the divided slope units being more likely to have units with scattered areas and sizes and unreasonable geometric slope shapes, resulting in poor accuracy of slope unit division. Summary of the invention

[0005] The present invention provides an optimal slope unit extraction method and system for earthquake landslide hazard assessment, which is used to solve the above-mentioned problem existing in the prior art, that is, how to improve the accuracy of slope unit division in the prior art. The present invention provides an optimal slope unit extraction method for earthquake landslide hazard assessment, and the method comprises:

[0006] Obtain the DEM grid data of the area to be measured and the circular standard deviation, minimum division area and initial runoff accumulation for slope unit division;

[0007] The slope unit division method based on the slope aspect uniformity determines the slope unit division result;

[0008] According to the slope unit division results, the shape rationality index and area rationality index of the slope unit of each division sequence are determined. By estimating the relative importance of the shape rationality index and the area rationality index, the principal component analysis method is used to construct the minimum loss objective function for slope unit division.

[0009] According to the minimum loss objective function, the optimal division threshold of the circle standard deviation and the initial confluence accumulation is determined, and based on the optimal division threshold, the optimal slope unit division result of the area to be tested is obtained.

[0010] Optionally, the slope unit division method based on slope aspect uniformity determines the slope unit division result, specifically comprising:

[0011] The DEM grid data is divided into halves to obtain multiple maximized initial slope units, and then the initial slope division unit is further divided to obtain multiple slope units. When the average area of ​​the divided slope unit is less than the minimum division area, the divided multiple slope units are output and used as the slope unit division result;

[0012] Otherwise, further divide the divided multiple slope units into halves and use them as the latest divided slope units, then determine whether the circular standard deviation of the latest divided slope units is less than a preset circular standard deviation threshold, and if so, output multiple latest divided slope units as the slope unit division result;

[0013] Otherwise, the minimum division area threshold is updated, and the DEM raster data is repeatedly divided into half to obtain multiple maximized initial slope units. The initial slope division unit is further divided to obtain multiple slope units, and it is determined whether the average area of ​​the slope unit after division is less than the minimum division area, until the slope unit division result meets the conditions.

[0014] Optionally, determining the shape rationality index and area rationality index of the slope units of each division sequence according to the slope unit division result specifically includes:

[0015] According to the slope unit division results, the shape rationality index is obtained in the following way:

[0016]

[0017] The area rationality index is obtained in the following way:

[0018]

[0019] Among them, S is the shape rationality index, s i , are the average length-to-width ratio difference of each slope unit and the average length-to-width ratio difference of the total unit, A is the area rationality index, and a i , are the area of ​​each slope unit and the total mean area respectively, and n is the number of divided slope units.

[0020] Optionally, the principal component analysis method is used to construct a minimum loss objective function for slope unit division, specifically including:

[0021] The principal component analysis method was used to obtain the relative importance values ​​of the area rationality index and the shape rationality index;

[0022] According to the relative importance values ​​of the area rationality index and the shape rationality index, the minimum loss objective function for slope unit division is constructed.

[0023] Optionally, constructing a minimum loss objective function for slope unit division according to the relative importance values ​​of the area rationality index and the shape rationality index specifically includes:

[0024] The minimum loss objective function of slope unit partitioning is obtained using the following formula:

[0025] F(a,s)=ω1A+ω2S

[0026] Among them, ω1 and ω2 are the relative importance values ​​of the area rationality index and the shape rationality index respectively.

[0027] The present invention provides an optimal slope unit extraction system for earthquake landslide hazard assessment, comprising:

[0028] An acquisition module is used to obtain the DEM grid data of the area to be measured and the circular standard deviation, the minimum division area and the initial runoff accumulation for slope unit division;

[0029] A partitioning module is used for determining a slope unit partitioning result based on a slope aspect uniformity slope unit partitioning method;

[0030] A construction module is used to determine the shape rationality index and area rationality index of the slope units of each division sequence according to the slope unit division result, and to construct a minimum loss objective function for slope unit division by estimating the relative importance of the shape rationality index and the area rationality index and using the principal component analysis method;

[0031] The determination module is used to determine the optimal division threshold of the circle standard deviation and the initial confluence accumulation according to the minimum loss objective function, and obtain the optimal slope unit division result of the area to be tested based on the optimal division threshold.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides an optimal slope unit extraction method for earthquake landslide hazard assessment, which divides the acquired DEM raster data by adopting a dichotomy method, and determines the slope unit division result by combining the circle standard deviation, the minimum division area and the initial runoff accumulation used for slope unit division; according to the slope unit division result, by considering the influence of the shape and area of ​​the slope unit on the division result, according to the geometric parameter information of the slope unit, the shape rationality index and the area rationality index of the slope unit are obtained; by performing corresponding weight calculations on the shape rationality index and the area rationality index, the minimum objective function for the slope unit division of a certain place can be obtained; according to the minimum loss objective function, by adjusting to determine the optimal division parameter threshold, based on the optimal division threshold, a more accurate slope unit division result of the area to be tested can be obtained, thereby improving the accuracy of the division between slope units. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0034] Figure 1 A flowchart of an optimal slope unit extraction method for earthquake landslide hazard assessment provided by an embodiment of the present invention;

[0035] Figure 2 A flow chart of a slope unit division method based on slope aspect uniformity provided in an embodiment of the present invention;

[0036] Figure 3 The calculation result of the minimum loss objective function value of slope unit partitioning provided by the embodiment of the present invention.

[0037] The above drawings have shown clear embodiments of the present invention, which will be described in more detail below. These drawings and text descriptions are not intended to limit the scope of the present invention in any way, but to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] At present, when the hydrological analysis method is used in the existing technology to extract slope units, although different slope areas can be divided according to the terrain characteristics, the specific influence of the geometric parameters and shape parameters of the slope units on the division results is ignored. Since the slope units are divided according to the terrain, there are significant differences in the terrain attribute characteristics within the unit as the terrain fluctuates in space. As a result, different slope unit division methods directly affect the results of earthquake landslide hazard assessment, thereby affecting the accuracy of the division between slope units.

[0040] In view of the above problems, the present invention provides a method for extracting optimal slope units for earthquake landslide hazard assessment. The method obtains the optimal division threshold of the corresponding division parameter by constructing a minimum loss objective function based on the shape rationality index and the area rationality index, thereby achieving the division of the optimal slope units.

[0041] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0042] Example 1

[0043] Figure 1 is a flow chart of an optimal slope unit extraction method for earthquake landslide hazard assessment provided by an embodiment of the present invention, such as Figure 1 As shown, this embodiment shows an optimal slope unit extraction method for earthquake landslide hazard assessment, including:

[0044] S101: Obtain DEM grid data of the area to be measured and the circle standard deviation, minimum division area and initial runoff accumulation used for slope unit division.

[0045] S102: Determine a slope unit division result based on a slope unit division method based on slope aspect uniformity.

[0046] like Figure 2 As shown in the figure, the DEM grid data is divided into two halves to obtain multiple maximized initial slope units (HB), and then the divided slope units are judged as flat ground units; when the divided initial slope unit is a flat ground unit, it is deleted, that is, the flat ground is removed, and then the initial slope unit (HB) after the flat ground removal operation is further iteratively divided into two halves; otherwise, the maximized initial slope unit (HB) is further iteratively divided into two halves to obtain N slope units (HB) in total. N );

[0047] After the division, N slope units (HB N ) is less than the minimum partition area Smin When the N slope units (HB N ) is output as the final division result; on the contrary, the N slope units (HB N ) is not less than the minimum partition area S min The unit is further divided into half to obtain N more subdivided slope units, and the N latest divided slope units HB are obtained. N , and determine the N latest divided slope units HB N Whether the circle standard deviation is less than the preset circle standard deviation V threshold;

[0048] If yes, then output N newly divided slope units HB N And as the final slope unit division result;

[0049] On the contrary, for the minimum partition area S min The threshold is updated, including re-dividing the DEM grid data into halves to obtain multiple maximized initial slope units (HB), and then judging the flat ground units for the divided slope units. After the judgment is completed, the maximized initial slope unit (HB) is further iteratively divided into halves to obtain a total of N slope units (HB N ), and then divide the N slope units (HB N ) is less than the minimum partition area S min Make a judgment; if so, the N slope units (HB N ) is output as the final division result; on the contrary, the N slope units (HB N ) is not less than the minimum partition area S min The unit is further divided into half to obtain N more subdivided slope units, and the N latest divided slope units HB are obtained. N , and determine the N latest divided slope units HB N Whether the circle standard deviation is less than the preset circle standard deviation V threshold value, until the division result meets the conditions.

[0050] S103: According to the slope unit division result, determine the shape rationality index and area rationality index of the slope unit of each division sequence, estimate the relative importance of the shape rationality index and the area rationality index, and use the principal component analysis method to construct the minimum loss objective function for slope unit division.

[0051] Optionally, according to each sequence slope unit after the initial division, the shape rationality index is obtained in the following manner:

[0052]

[0053] The area rationality index is obtained in the following way:

[0054]

[0055] Among them, S is the shape rationality index, s i , are the average length-to-width ratio difference of each slope unit and the average length-to-width ratio difference of the total unit, A is the area rationality index, and a i , are the area of ​​each slope unit and the total mean area respectively, and n is the number of divided slope units.

[0056] Optionally, the minimum loss objective function of slope unit partitioning is obtained using the following formula:

[0057] F(a,s)=ω1A+ω2S

[0058] Among them, ω1 and ω2 are the relative importance values ​​of the area rationality index and the shape rationality index respectively.

[0059] S104: According to the minimum loss objective function, the optimal division threshold of the circle standard deviation and the initial confluence accumulation is determined, and based on the optimal division threshold, the optimal slope unit division result of the area to be measured is obtained.

[0060] Example 2

[0061] In this embodiment, the area to be tested is selected for division of the optimal slope unit. The geographical range of the area to be tested is 31.364°-31.741°N, 102.698°-103.499°E. Figure 1 Based on the embodiments, the optimal slope unit extraction method for earthquake landslide hazard assessment is described in detail.

[0062] First, the DEM grid of the area to be measured is used as the initial terrain division data; wherein the resolution of the grid data can be 13m.

[0063] Select a set of circle standard deviation V and minimum partition area S for the area to be measured min , the initial confluence accumulation C parameter combination sequence, the parameter combination sequence can be: circle standard deviation V = [0.1, 0.2, 0.3, 0.4, 0.5], minimum division area S min =

[15000] , initial cumulative flow C = [2.5×10 5 , 3×10 5 , 3.5×10 5 , 4×10 5 , 4.5×10 5 , 5×10 5], the minimum division unit area threshold a =

[15000] , and a total of 30 groups of division schemes are generated.

[0064] Get the S and A values ​​of each partitioning scheme respectively, such as Figure 3 As shown in the figure, the shape rationality index value S and area rationality index value A corresponding to each of the 30 division schemes show a certain correlation with the initial confluence accumulation C.

[0065] For example, when the C value remains the same, 2.5×10 5 , 3×10 5 , 3.5×10 5 , 4×10 5 , 4.5×10 5 , 5×10 5 The shape rationality index value S and area rationality index value A of the six groups of initial confluence C under the combinations of circle standard deviations of 0.1, 0.2, 0.3, 0.4, and 0.5 are consistent and are not affected by the change of circle standard deviation.

[0066] When the initial confluence C is different, the A and S values ​​change significantly. The initial confluence accumulation is 2.5×10 5 , 3×10 5 , 3.5×10 5 , 4×10 5 , 4.5×10 5 , 5×10 5 The combined values ​​of S and A values ​​([S, A]) of the set circle standard deviation V value sequences are [0.650, 3.50], [0.649, 3.408], [0.648, 3.313], [0.650, 3.217], [0.652, 3.125], [0.650, 3.024], and the minimum values ​​of [S, A] correspond to [0.1, 5e5], [0.2, 5e5], [0.3, 5e5], [0.4, 5e5], [0.5, 5e5] respectively.

[0067] At the same time, as the C value increases, the A value maintains a consistent decrease rate and gradually decreases, and the area difference between the divided slope units also gradually decreases, while the S value is not affected by the expansion of the C value, and its value is irregularly distributed at each C value. Figure 3 The changes in S and A values ​​in the figure show that the S and A values ​​obtained by dividing the same C value parameter combination under different circle standard deviations V obey the same distribution value. Therefore, in this embodiment, the 30×2-dimensional S and A index importance calculation matrix I 30×2 The dimension is reduced to 6×2 dimensions for calculation. The specific calculation formula is as follows:

[0068]

[0069] in,

[0070] Transformed into:

[0071]

[0072] in,

[0073] The 6×2-dimensional S and A indicator importance calculation matrix I 6×2 , mean matrix AI 6×2 Solve and calculate the matrix I based on the 30×2 dimensional S and A index importance 30×2 And the 6×2-dimensional S and A index importance calculation matrix I 6×2 , get the covariance value matrix CE between S and A values 2×2 , the calculation results are as follows:

[0074]

[0075] Solve the covariance value matrix CE between S and A values ​​respectively 2×2 Medium Matrix CE 2×2 The eigenvalues ​​of the eigenvectors S and A are calculated to be ω1 and ω2, which are 0.506 and -0.863 respectively. The minimum objective function for the slope unit division of the example area can be constructed. The specific formula is as follows:

[0076]

[0077] It can be seen from the analysis that the minimum F(a, s) value of the slope unit division in this example area only needs to obtain the initial flow accumulation C of six groups under any circle standard deviation V = [0.1, 0.2, 0.3, 0.4, 0.5] value = [2.5×10 5 , 3×10 5 , 3.5×10 5 , 4×10 5 , 4.5×10 5 , 5×10 5 ] value corresponding to the F(a, s) value.

[0078] In this example, V = 0.1, C = [2.5 × 10 5 , 3×10 5 , 3.5×10 5 , 4×10 5 , 4.5×10 5 , 5×10 5] to form a partitioning sequence, and the F(a, s) values ​​of each scheme are calculated in turn. It is shown that when C = 5e5 and the circular standard deviation V = any value in [0.1, 0.2, 0.3, 0.4, 0.5], the corresponding F(a, s) value is the smallest, and F(a, s) = 0.778. In this embodiment, V = 0.1 and C = 5e5 are arbitrarily selected to form a partitioning parameter combination sequence, and finally a total of 5507 slope units are divided in the example area, among which the slope unit area is greater than 9600m 2 The number of units accounted for 52.9%, and the mean and standard deviation of the area of ​​the slope units were 16391m 2 、29775m 2 .

[0079] Example 3

[0080] The present invention provides an optimal slope unit extraction system for earthquake landslide hazard assessment, comprising:

[0081] An acquisition module is used to obtain the DEM grid data of the area to be measured and the circular standard deviation, the minimum division area and the initial runoff accumulation for slope unit division;

[0082] A partitioning module is used for determining a slope unit partitioning result based on a slope aspect uniformity slope unit partitioning method;

[0083] A construction module is used to determine the shape rationality index and area rationality index of the slope units of each division sequence according to the slope unit division result, and to construct a minimum loss objective function for slope unit division by estimating the relative importance of the shape rationality index and the area rationality index and using the principal component analysis method;

[0084] The determination module is used to determine the optimal division threshold of the circle standard deviation and the initial confluence accumulation according to the minimum loss objective function, and obtain the optimal slope unit division result of the area to be tested based on the optimal division threshold.

[0085] The specific definition of the optimal slope unit extraction system for earthquake landslide hazard assessment can be found in the above-mentioned definition of the optimal slope unit extraction method for earthquake landslide hazard assessment, which will not be repeated here. Each module in the above-mentioned optimal slope unit extraction system for earthquake landslide hazard assessment can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0086] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0087] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present invention.

Claims

1. A method for extracting optimal slope units for earthquake landslide hazard assessment, characterized in that: include: Obtain the DEM grid data of the area to be measured and the circular standard deviation, minimum division area and initial runoff accumulation for slope unit division; The slope unit division method based on the slope aspect uniformity determines the slope unit division result; The slope unit division method based on slope aspect uniformity determines the slope unit division result, specifically comprising: The DEM grid data is divided into halves to obtain multiple maximized initial slope units, and then the initial slope division unit is further divided to obtain multiple slope units. When the average area of ​​the divided slope unit is less than the minimum division area, the divided multiple slope units are output and used as the slope unit division result; Otherwise, further divide the divided multiple slope units into halves and use them as the latest divided slope units, then determine whether the circular standard deviation of the latest divided slope units is less than a preset circular standard deviation threshold, and if so, output multiple latest divided slope units as the slope unit division result; Otherwise, the minimum division area threshold is updated, and the DEM grid data is repeatedly divided into half to obtain multiple maximized initial slope units, and then the initial slope division unit is further divided to obtain multiple slope units, and it is determined whether the average area of ​​the slope unit after division is less than the minimum division area, until the slope unit division result meets the conditions; According to the slope unit division results, the shape rationality index and area rationality index of the slope unit of each division sequence are determined. By estimating the relative importance of the shape rationality index and the area rationality index, the principal component analysis method is used to construct the minimum loss objective function for slope unit division. The step of determining the shape rationality index and area rationality index of the slope units of each division sequence according to the slope unit division result specifically includes: According to the slope unit division results, the shape rationality index is obtained in the following way: ； The area rationality index is obtained in the following way: ； Among them, S is the shape rationality index, are the average length-to-width ratio difference of each slope unit and the average length-to-width ratio difference of the total unit, respectively; A is the area rationality index, are the unit area of ​​each slope and the total mean area, n is the number of slope units divided; The principal component analysis method is used to construct a minimum loss objective function for slope unit division, which specifically includes: The principal component analysis method was used to obtain the relative importance values ​​of the area rationality index and the shape rationality index; According to the relative importance values ​​of the area rationality index and the shape rationality index, a minimum loss objective function for slope unit division is constructed; According to the minimum loss objective function, the optimal division threshold of the circle standard deviation and the initial confluence accumulation is determined, and based on the optimal division threshold, the optimal slope unit division result of the area to be tested is obtained.

2. An optimal slope unit extraction system for earthquake landslide hazard assessment, characterized in that: include: An acquisition module is used to obtain the DEM grid data of the area to be measured and the circular standard deviation, the minimum division area and the initial runoff accumulation for slope unit division; A division module is used for determining a slope unit division result based on a slope unit division method of slope aspect uniformity; the slope unit division method based on slope aspect uniformity determines a slope unit division result, specifically comprising: The DEM grid data is divided into halves to obtain multiple maximized initial slope units, and then the initial slope division unit is further divided to obtain multiple slope units. When the average area of ​​the divided slope unit is less than the minimum division area, the divided multiple slope units are output and used as the slope unit division result; Otherwise, further divide the divided multiple slope units into halves and use them as the latest divided slope units, then determine whether the circular standard deviation of the latest divided slope units is less than a preset circular standard deviation threshold, and if so, output multiple latest divided slope units as the slope unit division result; Otherwise, the minimum division area threshold is updated, and the DEM grid data is repeatedly divided into half to obtain multiple maximized initial slope units, and then the initial slope division unit is further divided to obtain multiple slope units, and it is determined whether the average area of ​​the slope unit after division is less than the minimum division area, until the slope unit division result meets the conditions; A construction module is used to determine the shape rationality index and area rationality index of the slope units of each division sequence according to the slope unit division result, and to construct a minimum loss objective function for slope unit division by estimating the relative importance of the shape rationality index and the area rationality index using the principal component analysis method; the determining the shape rationality index and the area rationality index of the slope units of each division sequence according to the slope unit division result specifically includes: According to the slope unit division results, the shape rationality index is obtained in the following way: ； The area rationality index is obtained in the following way: ； Among them, S is the shape rationality index, are the average length-to-width ratio difference of each slope unit and the average length-to-width ratio difference of the total unit, respectively; A is the area rationality index, are the unit area of ​​each slope and the total mean area, n is the number of slope units divided; The principal component analysis method is used to construct a minimum loss objective function for slope unit division, which specifically includes: The principal component analysis method was used to obtain the relative importance values ​​of the area rationality index and the shape rationality index; According to the relative importance values ​​of the area rationality index and the shape rationality index, a minimum loss objective function for slope unit division is constructed; The determination module is used to determine the optimal division threshold of the circle standard deviation and the initial confluence accumulation according to the minimum loss objective function, and obtain the optimal slope unit division result of the area to be tested based on the optimal division threshold.

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