CN-121637902-B - Flood simulation method fully utilizing topographic data

Abstract

The invention discloses a flood simulation method fully utilizing topographic data, which belongs to the technical field of hydraulic engineering flood simulation and flood control and disaster reduction, and comprises the following steps of step 1, rasterizing topographic data; step 2, dividing unstructured grids, step 3, analyzing the topological relation between grids and grid space, step 4, solving the water level-storage relation of unstructured grid units, step 5, calculating the elevation of grid nodes, and step 6, constructing a discrete format of a flood simulation model. The method is based on the thought of water level-storage, can fully utilize all high-precision topographic data under the condition of not increasing calculated amount, completely delineate local micro-topography and water storage capacity in each cell, improve flood simulation precision and provide scientific basis for flood control and disaster reduction.

Inventors

• YU HAIJUN
• WU BINBIN
• YU WANGYANG
• SUN LIN
• SHI HONGJIAN
• SONG ANQI
• LIU CHUNGUO

Assignees

• 中国水利水电科学研究院

Dates

Publication Date

20260512

Application Date

20251205

Claims (3)

1. 1. A flood simulation method for fully utilizing terrain data, the method comprising the steps of: Step 1, performing rasterization processing on topographic data, namely acquiring high-precision topographic data of a research area, wherein the high-precision topographic data is meter-level or higher-resolution topographic data, and processing the topographic data into raster type data on the basis of not reducing the resolution of the data; Dividing the research area into a plurality of unstructured grids according to a certain size, wherein the grid division size is larger than the resolution of the topographic data, and the grid coordinate system is consistent with the topographic data coordinate system; Step 3, analyzing the space topological relation between grids and grids, namely performing space topological analysis on all grid units and grid topographic data of a research area, specifically analyzing how much area proportion of each grid is positioned on a specific grid based on space positions, if a grid R i completely falls into a grid C j , the area proportion R i,j =1, and if half of the grids fall into the grid, the area proportion R i,j =0.5; Step 4, solving the water level-storage relation of the unstructured grid unit, namely solving the maximum possible water storage in the grid range under all characteristic water levels to form a water level-storage relation curve, wherein the characteristic water level values are respectively the elevation values of n grids when the grid C j is provided with n grids, and are 1 、 2 、...、 n And calculating the storage amount of the grid unit C j under a certain characteristic water level Z k by adopting the formula (1): (1) wherein: For a grid elevation value numbered i, i is the grid number, representing the grid falling into grid cell C j , i.e ; The formula (1) is further rewritten as a water level-water depth relationship curve: (2) (3) wherein: for the water level of the grid unit The corresponding water depth value, m; M 2 , which is the area of the grid cell; is the maximum value in the characteristic water level; Step 5, calculating the grid node elevation, namely firstly calculating the ratio of the size l of the grid edge element to the grid resolution w, assuming P CR , then determining the number of nearest grids around the node according to the size of P CR , assuming M R , and finally calculating the grid node elevation by adopting the average value of M R grids Gao Chengqu, wherein the calculation formula of P CR is as follows: (4) Wherein l s is the length of the s-th edge of the grid, and m is the total number of grid edge elements; And 6, constructing a discrete format of the flood simulation model by adopting an improved two-dimensional shallow water control equation and adopting a mode of solving a bottom slope term for line integration, wherein the specific formula is as follows: (5) (6) wherein: Is a time variable; And Is a coordinate; Is the depth of water; And Respectively is And A directional flow rate; Gravitational acceleration, S b represents the bottom slope term, wherein And The component of the base slope term in the x and y directions, respectively, S f represents the friction term, wherein And Friction term components in x and y directions, respectively; the source term caused by the bottom slope term is as follows: (7) Integrating equation (7) over the grid cells and converting to line integration yields: (8) wherein: b s is the bottom elevation of the s-th side of the grid, the average value of the node elevations at the two ends of the grid side is taken, the node elevation is calculated by adopting the method in the step 5, and n x 、n y respectively represents the external normal unit vectors in the x direction and the y direction; and carrying out flood simulation calculation by utilizing the flood simulation model constructed according to the discrete format and the method.
2. 2. The flood simulation method using the topographic data according to claim 1, wherein the unstructured grid in the step 2 is any type of unstructured grid including quadrangles, triangles and different types of mixed grids.
3. 3. The flood simulation method using the topographic data fully according to claim 1, wherein in step 5, the value of M R is: when P CR ＞10,M R = 21; when 5<P CR ≤10,M R =9; When 2<P CR ≤5,M R =4; when 1<P CR ≤2,M R =1.

Description

Flood simulation method fully utilizing topographic data Technical Field The invention belongs to the technical field of hydraulic engineering flood simulation and flood control and disaster reduction, and particularly relates to a flood simulation method for fully utilizing topographic data. Background The two-dimensional hydrodynamic model is a mainstream method for simulating surface flood, and the main idea is to discretely solve a two-dimensional shallow water equation by adopting a numerical method such as a finite volume method, a finite difference method and the like. The current mainstream flood two-dimensional simulation method adopts a finite volume method model of an unstructured grid. The two-dimensional model using unstructured grids generally divides a study area into a plurality of unstructured grids according to a certain size, and assigns the topography (i.e. the elevation data of the underlying surface) to a grid cell node (inclined bottom mode) or a grid cell center point (flat bottom mode). Due to the application of unmanned aerial vehicle and satellite remote sensing technologies, the terrain measurement becomes simpler, and the acquired terrain data has higher resolution than the traditional technical means, and can reach the meter level or even the centimeter level. For high-resolution topographic data, no matter which type of unstructured grid (triangle, quadrangle or mixture of multiple types) is adopted, the utilization of the data is insufficient, and the waste of data resources is caused. According to the traditional method, the elevation is defined at a central point or a node, and for sub-meter level elevation data, grid discrete size needs to be controlled at the sub-meter level to fully utilize the topographic data, but the sub-meter level grid size often causes ultra-large grid number, so that model calculation efficiency and result data storage and display efficiency are greatly reduced. The grids are divided according to the conventional size (such as a quadrilateral grid of 10 meters, the average area of the grids is about 100 flat meters), if the terrain is of the meter level (1 meter is assumed), 121 elevation points can exist in the range of a single grid, if a flat bottom mode is adopted, at most 1 elevation data can be set for the single grid, if an inclined bottom mode is adopted, at most 4 elevation data can be utilized for the single grid, and the micro-terrain in the grid unit cannot be effectively reflected. Therefore, how to realize the full utilization of the topographic data in the flood simulation method is a technical problem to be solved in the art. Disclosure of Invention The invention aims to provide a flood simulation method which fully utilizes terrain data so as to solve the technical problems. In order to achieve the above purpose, the present invention provides the following technical solutions: The invention discloses a flood simulation method fully utilizing topographic data, which comprises the following steps: Step 1, performing rasterization processing on topographic data, namely acquiring high-precision topographic data of a research area, wherein the high-precision topographic data is meter-level or higher-resolution topographic data, and processing the topographic data into raster type data on the basis of not reducing the resolution of the data; Dividing the research area into a plurality of unstructured grids according to a certain size, wherein the grid division size is larger than the resolution of the topographic data, and the grid coordinate system is consistent with the topographic data coordinate system; Step 3, analyzing the space topological relation between grids and grids, namely performing space topological analysis on all grid units and grid topographic data of a research area, specifically analyzing how much area proportion (assumed to be R i,j) of each grid (assumed to be R i) is positioned on a specific grid (assumed to be C j) based on space positions, if the grid R i completely falls into the grid C j, R i,j =1, and if half falls into the grid, R i,j =0.5; Step 4, solving the water level-storage relation of the unstructured grid unit, namely solving the maximum possible water storage in the grid range under all characteristic water levels to form a water level-storage relation curve, and assuming that n grids exist in the grid C j range, respectively taking the characteristic water level values as elevation values of the n grids, and assuming that 1、2、...、n And calculating the storage amount of the grid unit C j under a certain characteristic water level Z k by adopting the formula (1): (1) wherein: For a grid elevation value numbered i, i is the grid number, representing the grid falling into grid cell C j, i.e ; The formula (1) is further rewritten as a water level-water depth relationship curve: (2) (3) wherein: for the water level of the grid unit The corresponding water depth value, m; M 2, which is the area of the