CN-116561476-B - Method for automatically realizing small-basin mountain torrent flood flow and inundation forecast

CN116561476BCN 116561476 BCN116561476 BCN 116561476BCN-116561476-B

Abstract

The invention discloses a method for automatically realizing flood flow and inundation forecast of mountain floods in a small river basin, which comprises the steps of S1, obtaining parameters of a preset river basin, including grid water flow direction, grid gradient, river basin river network and river network width, S2, obtaining a CN value and a K value of each grid in the preset river basin, S3, calculating the yield and confluence condition of each grid in the preset river basin, S4, constructing a mountain floods inundation model based on a open source model LISFLOOD-FP, and S5, automatically calculating and outputting a river basin flow forecast value and a flood inundation range through the mountain floods inundation model. The invention can realize automatic real-time prediction from rainfall to flow prediction to inundation.

Inventors

WANG NAIYU
WANG YINGJUN
YAN SHANG

Assignees

浙江大学

Dates

Publication Date: 20260508
Application Date: 20230106

Claims (8)

1. A method for automatically realizing flood flow and inundation forecast of mountain floods in small river basin, which is characterized by comprising the following steps: s1, acquiring parameters of a preset river basin, wherein the parameters comprise grid water flow direction, grid gradient, river basin river network and river network width; s2, acquiring a CN value and a K value of each grid in a preset flow field; s3, calculating the flow rate and the confluence condition of each grid in a preset flow field; The step S3 specifically comprises the following steps: S3.1, acquiring data of a rainfall station of a preset river basin, and obtaining surface rainfall data through interpolation calculation; s3.2, calculating the yield of each grid through an SCS-CN model; step S3.3, searching a water outlet of the river basin based on the grid water flow direction obtained in the step S1, marking 0, flowing into a grid marked 0 as 1, flowing into a grid marked 1 as 2, and so on until the whole river basin is traversed, reading the number of the grid, and obtaining the sequence of grid confluence; S3.4, calculating the flow velocity of the water flow in the grids, multiplying the flow velocity by the time step to obtain the distance of the water flow, wherein the distance of the water flow is used for judging the grids reached by the water flow in the time step; s3.5, calculating grid flow of the river course by adopting Ma Sijing root method; s4, constructing a mountain torrent inundation model based on an open source model LISFLOOD-FP; The step S4 specifically comprises the following steps: S4.1, counting the grid number of the adjacent river grids flowing into the river grid according to the grid water flow direction, wherein the grid number of the river grid flowing into the starting river grid is 0, the grid number of the river grid flowing into the grid point of the branch flow is more than or equal to 2, and the outlet point of the river basin is not converged into other river grids of the river basin; Step S4.2, extracting the flow process of the starting point and the outlet of the river and the inflow point of the tributary in the river grid flow process obtained by calculation in the step S3; s4.3, obtaining a river Manning roughness coefficient and a flood area Man Ning Caolv coefficient through a lookup table according to river characteristics and flood area characteristics; Step S4.4, preparing data according to LISFLOOD-FP input requirements by using a DEM of a preset river basin, a river grid flow process, a river width, a river Manning roughness coefficient, a Manning roughness coefficient of a flood area, an address of an input/output file, a total duration of flood forecast of a mountain torrent, an initial time step and whether a river flow simulation adopts diffusion waves or not, wherein the river grid flow process, the river width, the river Manning roughness coefficient, the Manning roughness coefficient of the flood area are obtained in the step S4.2; and S5, automatically calculating and outputting a river basin flow forecast value and a flood inundation range through a mountain flood inundation model.
2. The method for automatically realizing the flood flow and the inundation forecast of the mountain floods in the small river basin according to claim 1, wherein in the step S1, the grid water flow direction, the grid gradient, the river basin river network and the river network width are obtained through the DEM, specifically comprising the following steps: s1.1, downloading DEM data of a preset river basin through a public website; s1.2, filling the downloaded DEM with a hollow by adopting an ArcGIS; s1.3, calculating the flow direction of grid water flow by adopting an ArcGIS; s1.4, calculating the elevation difference of adjacent grids by adopting an ArcGIS, and obtaining the gradient of each grid; s1.5, calculating the number of grids flowing into the upstream of each grid by counting the flow direction of the grid water flow by adopting an ArcGIS, obtaining the water collection area of the grid, setting a water collection area threshold value, and extracting a river network of a preset river basin; S1.6, designating a point of a preset river basin by adopting an ArcGIS, searching a water outlet of the river basin according to the grid water flow direction, and comprehensively analyzing the river network, the water outlet of the river basin and the grid water flow direction to obtain the river network of the preset river basin; And S1.7, obtaining the river network width.
3. The method for automatically realizing the flood flow and the inundation forecast of the mountain floods in the small river basin according to claim 1, wherein the step S2 specifically comprises: S2.1, acquiring soil utilization conditions and soil types of a preset river basin through a public website, classifying the soil of the preset river basin into four types according to infiltration rates, searching a CN value relation table according to the soil utilization conditions of each type of soil, investigating the soil water content condition in the early stage, and acquiring the CN value of a grid according to different wetting conditions and the CN value relation table; And S2.2, searching a gradient flow velocity coefficient table according to the soil utilization condition, and reading the K value of the grid.
4. The method for automatically realizing the flood flow and the inundation forecast of the mountain floods in the small river basin according to claim 1, wherein in the step S3.2, the yield of each grid is calculated as follows: (1); In the above-mentioned method, the step of, The unit is mm for the runoff; Is the initial loss coefficient; Rainfall for a period of time; For the maximum possible hold up of the basin, the formula is calculated as follows: (2); In the above-mentioned method, the step of, The value is determined by the soil type, land use and soil pre-water conditions.
5. The method for automatically realizing the flood flow and the inundation forecast of the mountain floods in the small river basin according to claim 1, wherein in the step S3.4, the flow rate of the water flow in the grid is calculated as follows: (3); In the above-mentioned method, the step of, Is the flow rate; is a flow rate coefficient, at least determined by land utilization characteristics; Is an experience coefficient; Is a gradient.
6. The method for automatically realizing small-river-area mountain torrent flood flow and inundation prediction according to claim 1, wherein in step S4, a mountain torrent inundation model is calculated by using an open source model LISFLOOD-FP, and wherein the river water depth of each river grid point is calculated by using a shallow water equation: ; ; In the above-mentioned method, the step of, And Is that Flow and speed in the direction; Is the cross-sectional area of the river channel; gravitational acceleration; is the coefficient of Manning roughness; is the hydraulic radius; Is the depth of water; is the elevation of the river bed.
7. The method for automatically realizing the flood flow and the inundation forecast of the mountain floods in the small river basin according to claim 1, wherein the step S5 specifically comprises: S5.1, running LISFLOOD-FP model to generate exe file; step S5.2, using the data prepared in the step S4.4 as an input file, and calling the exe file generated in the step S5.1 to generate inundation data; and S5.3, reading the inundated data, and storing the inundated data in geotiff format.
8. The method for automatically realizing the flood flow and the inundation forecast of the mountain floods in the small river basin according to claim 7, wherein in the step S5.2, the format of inundation data output by the LISFLOOD-FP model is defaulted to be a WD file, and the WD file is changed into an output csv, txt or excel format file through a preset algorithm.

Description

Method for automatically realizing small-basin mountain torrent flood flow and inundation forecast Technical Field The invention relates to the technical field of flood forecasting, in particular to a method for automatically realizing small-basin mountain torrent flood flow and inundation forecasting. Background The flood disaster is one of the serious natural disasters, and the small-river-area mountain floods are used as a common flood disaster, and have the characteristics of high occurrence frequency, strong destructive burstiness, high forecast and prediction difficulty and the like, and have higher requirements on the accuracy of forecast and early warning and the calculation efficiency of the model. The small-river mountain torrent forecasting and early warning mode includes critical rainfall and hydrographic hydrodynamic model. The critical rainfall adopts an empirical formula, so that unevenness of rainfall is reflected by generalized parameters, and the precision and accuracy of forecasting and early warning are easily influenced by spatial distribution of rainfall and topography. The lumped hydrologic model has good flow forecasting effect on the designated outlet section and lacks flow forecasting on other sections of the river channel. The distributed (grid) hydrologic model can conduct flow forecast on a plurality of river sections, but is complicated to write, and cannot obtain a flood inundation range. Disclosure of Invention In order to overcome the defects of the technology, the invention provides a method for automatically realizing the flow and the inundation forecast of the mountain floods in the small river basin, and realizes the automatic real-time forecast from rainfall to flow forecast to inundation range. Term interpretation: 1. DEM Digital Elevation Model, digital elevation model. 2. SCS-CN model The Soil Conservation ServiceRunoffCurveNumber Method. 3. K value, flow rate coefficient. 4. CN value, curve Number value. The technical scheme adopted for overcoming the technical problems is as follows: A method for automatically realizing small-basin mountain torrent flood flow and inundation forecast, comprising the following steps: s1, acquiring parameters of a preset river basin, wherein the parameters comprise grid water flow direction, grid gradient, river basin river network and river network width; s2, acquiring a CN value and a K value of each grid in a preset flow field; s3, calculating the flow rate and the confluence condition of each grid in a preset flow field; s4, constructing a mountain torrent inundation model based on an open source model LISFLOOD-FP; and S5, automatically calculating and outputting a river basin flow forecast value and a flood inundation range through a mountain flood inundation model. Further, in step S1, the grid water flow direction, the grid gradient, the river basin river network and the river network width are obtained through the DEM, which specifically includes: s1.1, downloading DEM data of a preset river basin through a public website; s1.2, filling the downloaded DEM with a hollow by adopting an ArcGIS; s1.3, calculating the flow direction of grid water flow by adopting an ArcGIS; s1.4, calculating the elevation difference of adjacent grids by adopting an ArcGIS, and obtaining the gradient of each grid; s1.5, calculating the number of grids flowing into the upstream of each grid by counting the flow direction of the grid water flow by adopting an ArcGIS, obtaining the water collection area of the grid, setting a water collection area threshold value, and extracting a river network of a preset river basin; S1.6, designating a point of a preset river basin by adopting an ArcGIS, searching a water outlet of the river basin according to the grid water flow direction, and comprehensively analyzing the river network, the water outlet of the river basin and the grid water flow direction to obtain the river network of the preset river basin; And S1.7, obtaining the river network width. Further, step S2 specifically includes: S2.1, acquiring soil utilization conditions and soil types of a preset river basin through a public website, classifying the soil of the preset river basin into four types according to infiltration rates, searching a CN value relation table according to the soil utilization conditions of each type of soil, investigating the soil water content condition in the early stage, and acquiring the CN value of a grid according to different wetting conditions and the CN value relation table; And S2.2, searching a gradient flow velocity coefficient table according to the soil utilization condition, and reading the K value of the grid. Further, the step S3 specifically includes: S3.1, acquiring data of a rainfall station of a preset river basin, and obtaining surface rainfall data through interpolation calculation; s3.2, calculating the yield of each grid through an SCS-CN model; step S3.3, searching a water outlet of the river basin bas