DEM-based mountainous river-type reservoir inundation area rapid generation method and system

Abstract

This invention relates to the field of land acquisition and physical indicator surveys for water conservancy and hydropower engineering construction, specifically to a method and system for rapidly generating inundation areas of mountainous river-type reservoirs based on high-precision DEMs. It aims to solve the problems of poor accuracy, long processing time, and large human error in existing technologies for generating inundation areas. The method includes: acquiring or generating the reservoir river section DEM, river cross-section lines, and backwater meters, and preprocessing them; expanding the cross-section lines to divide the river into units; calculating the grid water level based on the inverse distance weighted interpolation method and comparing it with the DEM elevation to determine the inundation area grid; generating closed surface regions through boundary tracing and smoothing, and merging them to obtain the entire inundation area. This method balances efficiency and accuracy, supports dynamic generation of multiple schemes within seconds, improves analysis accuracy and efficiency, and is suitable for mountainous river-type reservoirs, providing data support for scheme comparison and physical surveys.

Description

Technical Field

[0001] This invention relates to the field of land acquisition and physical indicator survey for water conservancy and hydropower engineering construction, specifically to a method and system for rapidly generating inundation areas of mountainous river-type reservoirs based on DEM. Background Technology

[0002] The reservoir inundation zone is determined based on the reservoir's design flood backwater surface line, taking into account the effects of wind and waves, and after determining different safe freeboard values ​​for different inundation targets. In existing technologies, the commonly used method is to manually draw the reservoir inundation line based on cross-section and backwater calculation results, using CAD drawing software and referencing contour lines on topographic maps. In recent years, methods have also been employed, such as linear interpolation and densification of typical cross-sections, setting fixed values ​​according to the principle of equal water level differences, extracting elevation lines segmentally based on the DEM, and performing topological mapping to form different design flood reservoir inundation zones. In the field of defining flood reservoir inundation zones, attempts have also been made to fit water surface raster files based on flood water levels and use GIS software's raster calculator to perform algebraic operations between the water surface raster file and the DEM file to determine the raster file of the inundation area. These raster files are then converted to polygons and merged to form the reservoir inundation zone polygon file.

[0003] The existing methods mainly have the following problems: 1) Manually drawing the flood backwater lines of different objects is time-consuming and labor-intensive, and it is difficult to control human error, making it difficult to meet the requirements of rapid range generation under the current situation; 2) After densifying the cross-sections of the design flood backwater results, the elevation lines are extracted from the DEM to form the reservoir inundation area. However, the density of the cross-section densification is not high enough, which can easily lead to poor accuracy of the reservoir inundation area results, and it is still relatively time-consuming; 3) The method of fitting the water surface raster file based on the flood level and performing algebraic operations with the DEM file to determine the inundation area, and then converting the raster to a surface and merging it into a reservoir inundation area surface file can be used in the simulation analysis of flood range of small and medium-sized rivers, and can also be applied to the extraction of the land acquisition range of small reservoirs in mountainous areas. However, for cases involving a wide area and high DEM accuracy, the amount of calculation is large, and it is also too time-consuming.

[0004] Therefore, there is an urgent need for a method and system that balances computational efficiency and accuracy and is suitable for generating inundation zones of mountainous river-type reservoirs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for rapidly generating inundation areas of mountainous river-type reservoirs based on DEM, thereby solving at least one of the aforementioned technical problems in the existing technologies.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for rapidly generating inundation zones of mountainous river-type reservoirs based on DEM, comprising:

[0008] S1: Obtain or generate a digital elevation model (DEM) of the river section where the reservoir is located;

[0009] S2: Obtain the cross-sectional line of the river section where the reservoir is located and perform data preprocessing;

[0010] S3: Based on the design water level return water meter data of each section, and in accordance with the construction land acquisition and treatment scope definition specifications, obtain the return water meters corresponding to the reservoir inundation area of ​​each section of the reservoir, and perform data preprocessing.

[0011] S4: Based on the location of the river cross-section line, extend the river cross-section line to ensure that it fully intersects with the boundaries on both sides of the river. Based on the extended cross-section line, divide the entire river into multiple river units.

[0012] S5: Based on the river channel extension cross-section line, backwater meter, and reservoir river section digital elevation model (DEM) at both upstream and downstream ends, for each grid cell within each river cell, when the upstream and downstream water levels are inconsistent, the grid water level value is calculated one by one using the inverse distance weighted interpolation method; when the water level is at a constant level, the grid water level is directly read from the cross-section water level value, and by comparing it with the grid elevation value in the DEM, the grid cells with water level values ​​higher than the elevation values ​​are marked as inundation zone grid cells that meet the conditions.

[0013] S6: Based on the inundation area grid that meets the conditions, the boundary tracking algorithm generates an ordered coordinate sequence of topologically closed contour boundaries and constructs vector polygons. At the same time, the smoothing algorithm is used to smooth the polygon boundaries, and finally the closed surface vector file of the reservoir inundation area within each channel unit is obtained.

[0014] S7: Merge the reservoir inundation areas of multiple river units separately to obtain the entire reservoir inundation area.

[0015] Preferably, the method for generating the digital elevation model (DEM) of the river section where the reservoir is located in step S1 includes:

[0016] Obtain contour lines and elevation points from the topographic map;

[0017] Digital elevation models (DEMs) are generated using GIS software with irregular triangular meshes or Kriging interpolation algorithms.

[0018] Preferably, the data preprocessing of the river cross-section line in S2 includes:

[0019] Step 1: Process the cross-sectional lines into shapefile vector line data;

[0020] Step 2: Add attribute fields containing cross-section number and cross-section name to the cross-section line dataset, and enter the relevant information.

[0021] Preferably, the data preprocessing of the S3 return water meter includes:

[0022] Step 1: Consider the safety impact analysis to determine the backwater level in the reservoir inundation area and determine the backwater end section;

[0023] Step 2: Organize the return water meters according to the standard format of section number, section name, and scheme water level;

[0024] Step 3: Determine the upstream and downstream relationships at the cross-section and record them in the return water table.

[0025] Preferably, the method in S4 for dividing the entire river channel into multiple channel units based on the expanded cross-sectional lines includes:

[0026] Step 1: Set the extension factor to automatically extend both ends of the cross-section line until they fully intersect the riverbank;

[0027] Step 2: Based on the expanded cross-sectional lines and upstream and downstream relationships, the entire river channel is divided into multiple river channel units.

[0028] Preferably, the inverse distance weighted interpolation step in S5 includes:

[0029] Step 1: Determine the known water levels on the adjacent upstream and downstream cross-sections. Assume the point on the known cross-section is Qi(xi,yi). The corresponding water level value is zi;

[0030] Step 2: Determine the point to be interpolated and record its coordinates P(x,y);

[0031] Step 3: Calculate the distance di from the point to be interpolated to each known point Qi(xi,yi). The distance formula is:

[0032] ;

[0033] Step 4: Calculate the weight wi of each known point using the inverse distance weighting method. The weight formula is as follows:

[0034] ;

[0035] Where p is the distance weighting index, and p=2 is taken; when di=0, the known point is taken as the precise value of the interpolation point;

[0036] Step 5: Normalize the weights, the formula is:

[0037] , ;

[0038] Step 6: Based on the normalized weights and the known water level values, calculate the water level value Z of the point to be interpolated, P(x,y). The interpolation formula is:

[0039] .

[0040] Preferably, the boundary tracking algorithm in S6 includes extracting the contour boundary coordinates of the flooded area grid, wherein the contour boundary coordinates are selected from any of the following:

[0041] (a) Grid vertices;

[0042] (b) Grid center point;

[0043] (c) Center point of grid edge;

[0044] The smoothing algorithms in S6 include B-spline curve method and five-point smoothing method.

[0045] Secondly, the present invention provides a rapid generation system for mountainous river-type reservoir inundation areas based on DEM, used to implement the aforementioned rapid generation method for mountainous river-type reservoir inundation areas based on DEM, including:

[0046] The acquisition unit is used to acquire cross-section lines, cross-section water level values, and DEM elevation values.

[0047] The division unit is used to divide the reservoir into multiple channel units based on the cross-sectional lines;

[0048] The calculation unit, based on the DEM grid unit, calculates the water level value based on the interpolation of the return water meter at the upstream and downstream sections, and calculates the difference between the water level value and the elevation value.

[0049] The fitted unit smooths the outer boundary of the grid that meets the conditions to obtain the fitted reservoir inundation area;

[0050] The output unit merges data from multiple units and displays the output range results.

[0051] Thirdly, the present invention provides an electronic device, comprising:

[0052] Memory, used to store computer programs;

[0053] The processor, when executing the computer program, implements the previously described method for rapid generation of inundation areas of mountainous river channels and reservoirs.

[0054] Fourthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the method for rapid generation of inundation areas of mountainous river channels based on DEM as described above.

[0055] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0056] This invention provides a method and system for rapidly generating inundation areas of mountainous river-type reservoirs based on high-precision DEM (Digital Elevation Model). The method includes acquiring the DEM, cross-sectional lines, and backwater tables of the reservoir river section; dividing the reservoir river section into multiple river units; calculating the water level value of each grid cell within a river unit using inverse distance weighted interpolation; determining the grid cells that meet the criteria by comparing them with the DEM grid elevation values; constructing vector polygons using ordered coordinate sequences of the contour boundaries; smoothing the polygons to obtain segmented inundation areas; and merging these segments to obtain the entire inundation area. During scheme demonstration, the method supports the second-level dynamic generation of inundation areas for multiple different backwater schemes, providing reliable spatial data support for inundation impact analysis and decision support for scheme comparison. During physical surveys, the method combines high-resolution DEM data to achieve rapid generation of inundation areas with sub-meter accuracy, providing a good data foundation for defining the required scope of physical surveys. This effectively improves the accuracy and efficiency of inundation analysis and is applicable to the generation of various mountainous river-type reservoir inundation areas. Attached Figure Description

[0057] Figure 1 This is a flowchart of the method for generating the land acquisition scope for reservoir construction according to the present invention.

[0058] Figure 2 This is a schematic diagram of the reservoir construction land acquisition scope generation system of the present invention.

[0059] Figure 3 A schematic diagram showing the results of sorting the return water meters in the flooded area.

[0060] Figure 4 A schematic diagram for dividing the river into sections for cross-section expansion.

[0061] Figure 5 This is a schematic diagram illustrating the calculation and comparison of water levels within a grid within a river channel unit.

[0062] Figure 6 This is a schematic diagram of grid boundary extraction and smoothing.

[0063] Figure 7 This is a schematic diagram of the flooding line generated from the DEM. Detailed Implementation

[0064] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the present patent. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present patent.

[0065] Example 1

[0066] like Figure 1 The diagram shows a flowchart of a method for rapidly generating inundation areas of mountainous river-type reservoirs based on high-precision DEM. This method includes the following steps S1-S7:

[0067] S1: Obtain or generate a digital elevation model (DEM) of the river section where the reservoir is located.

[0068] In one possible implementation, S1 obtains the digital elevation model (DEM) of the river section where the reservoir is located, including:

[0069] The DEM of the river channel area was downloaded or collected through various channels.

[0070] In one possible implementation, the method for generating the digital elevation model (DEM) of the river section where the reservoir is located in S1 includes:

[0071] Obtain contour lines, elevation points, etc. from the topographic map;

[0072] Digital elevation models (DEMs) are generated using spatial interpolation algorithms such as irregular triangular meshes or kriging interpolation with GIS software.

[0073] In this embodiment, a 2*2m grid digital elevation model of the reservoir area is pre-established based on the contour lines around the reservoir. The contour lines should preferably be derived from the terrain during the dry season, with the lowest elevation lower than the normal water level of the current section and the highest elevation higher than the backwater level. This digital elevation model can clearly record the elevation data near the reservoir and river channel and can cover the area to be calculated.

[0074] It should be noted that the higher the grid precision of the DEM, the higher the accuracy of the generated results, but the slower the calculation speed.

[0075] S2: Obtain the cross-sectional line of the river section where the reservoir is located and perform data preprocessing.

[0076] In one possible implementation, the preprocessing of the river cross-section line in S2 includes:

[0077] Step 1: Process the cross-sectional lines into shapefile vector line data;

[0078] Step 2: Add attribute fields to the cross-section line dataset, which should include cross-section number and cross-section name fields, and enter relevant information.

[0079] It should be noted that the coverage area of ​​the cross-section line may include the entire main stream, as well as major tributaries.

[0080] S3: Based on the design water level return water meter data of each section, and in accordance with the construction land acquisition and treatment scope definition specifications, the return water meter of the reservoir inundation area is obtained, and the data is preprocessed.

[0081] In one possible implementation, the data preprocessing of the return water meter in S3 includes the following steps:

[0082] Step 1: Consider the impact analysis of safety and other factors to determine the backwater level in the reservoir inundation area and determine the backwater end section.

[0083] Step 2: Organize the return water meters according to the standard format such as section number, section name, and scheme water level.

[0084] Step 3: Determine the upstream and downstream relationships at the cross-section and record them in the return water table.

[0085] In a specific example, the processed water return meter data is as follows: Figure 3 As shown.

[0086] It should be noted that the section number and section name should correspond to the section number and section name in the section line.

[0087] S4: Based on the location of the river cross-section line, extend the cross-section line to ensure that the cross-section line and the river's two side boundaries fully intersect; based on the cross-section line, divide the entire river channel into multiple river units. For example... Figure 4 As shown.

[0088] In one possible implementation, the method in S4 for dividing the entire river channel into multiple channel units based on cross-sectional lines includes:

[0089] Step 1: After setting the cross-sectional extension multiple, the two ends of the cross-sectional line will be automatically extended to fully intersect with the riverbank to avoid the situation where the cross-sectional line is too short to intersect with the riverbank.

[0090] Step 2: Divide the entire river channel into multiple channel units based on the extended cross-section line and the upstream and downstream relationship.

[0091] S5: Based on the river channel extension cross-section lines, backwater meters, and the digital elevation model (DEM) of the reservoir river section at both upstream and downstream ends, for each grid within each river unit, when the upstream and downstream water levels are inconsistent, the grid water level value is calculated one by one using the inverse distance weighted interpolation method; when the water level is at a constant level, the grid water level is directly read from the cross-section water level value, and by comparing it with the DEM grid elevation value, the reservoir inundation zone grid within each river unit is determined according to the grids that meet the conditions.

[0092] In one possible implementation, the steps of the inverse distance weighted interpolation method in S5 are as follows:

[0093] Step 1: Determine the known water levels on the adjacent upstream and downstream cross-sections. Assume the point on the known cross-section is Qi(xi,yi). The corresponding water level value is zi;

[0094] Step 2: Determine the point to be interpolated and record its coordinates P(x,y);

[0095] Step 3: Calculate the distance di from the point to be interpolated to each known point Qi(xi,yi). The distance formula is:

[0096] ;

[0097] Step 4: Calculate the weight wi of each known point using the inverse distance weighting method. The weight formula is as follows:

[0098] ;

[0099] Where p is the distance weight index, usually p=2, that is, the reciprocal of the square of the distance is used as the weight; when di=0, in order to avoid division by zero error, the known point is used as the exact value of the point to be interpolated;

[0100] Step 5: Normalize the weights, the formula is:

[0101] , ;

[0102] Step 6: Based on the normalized weights and the known water level values, calculate the water level value Z of the point to be interpolated, P(x,y). The interpolation formula is:

[0103] .

[0104] Furthermore, the grid within the channel unit is based on the DEM grid. For example, if the DEM is 1*1m, then the grid unit for calculating the water level value is also 1*1m.

[0105] It should be noted that calculations generally start from the upstream section and gradually extend to the downstream section. For the reservoir's level section, where the backwater levels at both the upstream and downstream sections are the same, interpolation calculations are not performed; the section water level value can be directly taken to reduce the amount of calculation and improve calculation efficiency.

[0106] In one possible implementation, the grid that meets the conditions is determined in S5 by the following method:

[0107] Step 1: Extract the elevation values ​​of the DEM containing the grid;

[0108] Step 2: Compare the calculated grid water level values ​​with the elevation values ​​in the DEM;

[0109] Step 3: Mark all areas where the water level is higher than the DEM elevation value as eligible areas.

[0110] The principle of grid calculation and marking is illustrated as follows: Figure 5 As shown, the grid in the diagram is for illustrative purposes only and does not represent the actual division.

[0111] S6: Based on grid cells that meet the inundation conditions, an ordered coordinate sequence of topologically closed contour boundaries is generated through a boundary tracing algorithm, and vector polygons are constructed. At the same time, a smoothing algorithm is used to smooth the polygon boundaries, and finally, a vector file of the closed surface region of the reservoir inundation area within each channel cell is obtained.

[0112] In one possible implementation, S6 uses grid cells that meet the flooding conditions and a boundary tracing algorithm to generate an ordered sequence of topologically closed contour boundaries. This approach constructs vector polygons, directly vectorizing the flooded area in the raster topology space in one step. This effectively avoids the bottleneck of subsequent merging calculations after raster vectorization and avoids the time-consuming process of extracting boundary lines and performing topology processing, significantly improving processing efficiency. There are three ways to extract the contour boundary coordinates: first, grid vertices, which require slightly more smoothing work; second, grid center points, which typically result in a slightly smaller calculated flooded area but are more efficient; and third, the midpoints of grid edges.

[0113] In one possible implementation, the smoothing algorithms in S6 include the B-spline curve method and the five-point smoothing method, which can effectively eliminate sawtooth fluctuations. The B-spline curve method is more suitable for scenarios where accuracy is paramount, while the five-point smoothing method, with its lower computational complexity, is more suitable for scenarios where efficiency is prioritized. A schematic diagram of the smoothing results is shown below. Figure 6 As shown.

[0114] S7: Merge the reservoir inundation areas of multiple river units separately to obtain the entire reservoir inundation area.

[0115] In one possible implementation, S7 merges the reservoir inundation area surfaces of multiple adjacent channel units into a single complete surface file, thus obtaining the entire reservoir inundation area. Figure 7 As shown.

[0116] The following is a detailed description using specific examples.

[0117] Taking a specific water storage scheme for a reservoir as an example, a 2*2m grid DEM is generated based on contour lines. Cross-sectional lines are then organized according to the steps described above, and the return water meter is preprocessed (results are shown below). Figure 3 After obtaining the above data through the program page, the cross-section line is expanded to segment the reservoir channel. A schematic diagram of the segmentation result is shown in Figure 4. Interpolation calculations are performed segment by segment, and the results are compared with the DEM elevation to extract the boundaries that meet the criteria. A schematic diagram of the process is shown below. Figure 5 As shown. The smoothing result is as follows. Figure 6 As shown. After merging multiple data segments, the entire reservoir inundation area is as follows. Figure 7 As shown, the final range result is displayed in the browser window and can be exported for use.

[0118] The method described in this embodiment is simple and easy to operate. Even with high DEM accuracy, it can still quickly generate the range of different schemes for large and medium-sized reservoir areas, shortening the range drawing time, which is conducive to the advancement of project decision-making and provides rapid data support for the comparison of reservoir engineering schemes.

[0119] Example 2

[0120] To further illustrate, in conjunction with Example 1, Figure 2 This is a schematic diagram of a rapid generation system for inundation areas of mountainous river channels based on high-precision DEM provided in an embodiment of the present invention. The system includes:

[0121] The acquisition unit is used to acquire cross-section lines, cross-section water level values, and DEM elevation values.

[0122] The division unit is used to divide the reservoir into multiple channel units based on the cross-sectional lines;

[0123] The calculation unit, based on the DEM grid unit, calculates the water level value based on the interpolation of the return water meter at the upstream and downstream sections, and calculates the difference between the water level value and the elevation value.

[0124] The fitting unit smooths the outer boundary of the grid that meets the conditions to obtain the fitted flooded area;

[0125] The output unit merges data from multiple units and displays the output range results.

[0126] Example 3

[0127] In conjunction with Embodiment 1, this embodiment of the invention provides an electronic device, including a memory and a processor;

[0128] Memory, used to store computer programs;

[0129] The processor is used to implement, when executing a computer program, a method for rapidly generating inundation areas of mountainous river-type reservoirs based on high-precision DEM according to Embodiment 1, wherein the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0130] For specific examples, the memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out memory (FIFO), and / or last-in-first-out memory (FILO); the processor may be limited to microprocessors of the STM32F105 series, ARM (Advanced RISC Machines), x86 architecture processors, or processors with integrated NPU (neural-network processing units).

[0131] Example 4

[0132] To further illustrate with reference to Embodiment 1, this embodiment of the invention provides a computer program product that, when executed by a processor, implements the method for rapidly generating inundation areas of mountainous river-type reservoirs based on a high-precision DEM, as described in Embodiment 1. This program product can perform the operations described above and obtain the range results.

[0133] Example 5

[0134] To further illustrate with reference to Embodiment 1, this embodiment of the invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions that, when executed on a computer, perform a method for rapidly generating inundation areas of mountainous river channels based on a high-precision DEM, as described in the embodiment. The aforementioned instructions can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0135] Through the above description of the embodiments, those skilled in the art can clearly understand the software and hardware required for each embodiment. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium refers to a carrier for storing data, which may include, but is not limited to, floppy disks, optical disks, hard disks, flash memory, USB flash drives, etc. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.

[0136] The above embodiments are merely preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DEM-based method for quickly generating a submerged area of a mountainous river-type reservoir, characterized in that, The method comprises the following steps: S1: obtaining or generating a digital elevation model DEM of a river section where a reservoir is located; S2: obtaining a river section line of the river section where the reservoir is located, and performing data preprocessing; S3: based on the design water level backwater table data of each section, the reservoir submergence area corresponding to the backwater table of each section of the reservoir is obtained according to the construction land acquisition processing range definition specification, and data preprocessing is performed; S4: based on the position of the river section line, the river section line is extended to ensure that it fully intersects with the river bank on both sides, and the entire river is divided into multiple river units based on the extended section line; S5: based on the river extension section line at the upstream and downstream ends, the backwater table and the digital elevation model DEM of the reservoir section, for each grid in each river unit, when the upstream and downstream water levels are inconsistent, the grid water level value is calculated one by one according to the inverse distance weighted interpolation method; when the flat section, the grid water level directly reads the section water level value, by comparing with the grid elevation value in the DEM, the grid whose water level value is higher than the elevation value is marked as a submergence area grid meeting the condition; S6: based on the submergence area grid meeting the condition, the topologically closed contour boundary ordered coordinate sequence is generated by using the boundary tracking algorithm, and the vector polygon is constructed, and the polygon boundary is smoothed by using the smoothing algorithm, and finally the closed surface domain vector file of the reservoir submergence area in each river unit is obtained; S7: the reservoir submergence areas of multiple river units are merged respectively to obtain the entire reservoir submergence area.

2. The DEM-based mountainous river channel type reservoir inundation area rapid generation method according to claim 1, characterized in that, The method for generating the digital elevation model DEM of the river section where the reservoir is located in S1 comprises: obtaining contour lines and elevation point data in a topographic map; generating a digital elevation model DEM by using an irregular triangle network or a Kriging interpolation algorithm through GIS software.

3. The DEM-based mountainous river channel type reservoir inundation area rapid generation method according to claim 1, characterized in that, The data preprocessing of the river section line in S2 comprises: Step 1: processing the section line into shp format vector line data; Step 2: adding attribute fields containing section number and section name to the section line data set, and entering related information.

4. The DEM-based mountain river type reservoir inundation area rapid generation method according to claim 1, characterized in that, The data preprocessing of the backwater table in S3 comprises: Step 1: determining the backwater level of the reservoir submergence area considering the influence of safety superhigh, and determining the backwater end section; Step 2: arranging the backwater table according to the standard format of section number, section name and scheme water level; Step 3: combing the upstream and downstream relationship of the section, and recording in the backwater table.

5. The DEM-based mountainous river channel type reservoir inundation area rapid generation method according to claim 1, characterized in that, The method for dividing the entire river into multiple river units based on the extended section line in S4 comprises: Step 1: setting an extension multiple, and automatically extending the section line at both ends to fully intersect with the river bank; Step 2: dividing the entire river into multiple river units according to the extended section line and the upstream and downstream relationship.

6. The DEM-based mountain river channel type reservoir inundation area rapid generation method according to claim 1, characterized in that, The steps of the inverse distance weighted interpolation in S5 comprise: Step 1: Determine the known water level on the adjacent upstream and downstream cross-section lines, assuming the point on the known cross-section line is Qi(xi, yi) The corresponding water level value is zi; Step 2: determining the point to be interpolated, and recording its coordinates P(x, y); Step 3: calculating the distance di of the point to be interpolated to each known point Qi(xi, yi), and the distance formula is: ； Step 4: calculating the weight wi of each known point according to the inverse distance weighted method, and the weight formula is ； wherein p is the distance weight index, p=2 is taken; when di=0, the known point is taken as the exact value of the point to be interpolated; Step 5: normalizing the weight, and the formula is: ， ； Step 6: According to the normalized weight and the water level value of the known points, the water level value Z of the interpolation point P(x, y) is calculated, and the interpolation formula is: 。 7. The DEM-based mountainous river channel type reservoir inundation area rapid generation method according to claim 1, characterized in that, The boundary tracking algorithm in S6 includes extracting the contour boundary coordinate points of the submerged area grid, and the contour boundary coordinate points are selected from any one of the following: (a) Grid vertex; (b) Grid center point; (c) Grid edge center point; The smoothing algorithm in S6 includes B-spline curve method and five-point smoothing method.

8. A DEM-based mountainous river channel type reservoir inundation area rapid generation system, characterized in that, The method for implementing the DEM-based rapid generation of mountainous river-type reservoir submerged area according to any one of claims 1-7 comprises: An acquisition unit is configured to acquire a section line, a section water level value and a DEM elevation value; A division unit is configured to divide the reservoir into a plurality of river channel units according to the section line; A calculation unit is configured to calculate the water level value based on the upstream and downstream section backwater table interpolation and the DEM grid unit, and to calculate the difference between the water level value and the elevation value; A fitting unit is configured to perform smoothing processing on the grid outer boundary that meets the condition to obtain a fitted reservoir submerged area; An output unit is configured to perform merging processing on the plurality of unit data and to display and output the range result.

9. An electronic device, comprising: It comprises: A memory is configured to store a computer program; A processor is configured to execute the computer program to implement the DEM-based rapid generation of mountainous river-type reservoir submerged area according to any one of claims 1-7.

10. A computer program product, characterised in that, It comprises a computer program, which, when executed by a processor, implements the DEM-based rapid generation of mountainous river-type reservoir submerged area according to any one of claims 1-7.

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