Flood control protection area risk map construction method based on global hydrodynamic model

Abstract

The invention relates to the technical field of regional flood control protection, in particular to a flood control protection area risk map construction method based on a global hydrodynamic model, which comprises the following steps of: selecting a plurality of climate modes and historical reference data, and performing downscaling analysis and deviation correction on climate variables output by each climate mode; constructing a global hydrodynamic model, inputting the optimal climate mode and hydrological model result into the global hydrodynamic model, and performing global hydrodynamic flood risk simulation; and determining a calculation range of the flood control protection area according to an estimation result of the long-duration dynamic flood risk map, and constructing the long-duration dynamic flood risk map of the flood control protection area. The flood control protection area is estimated and determined in combination with the global flood model, the dynamic risk model of the regional flood control protection area is constructed, and the accuracy of the flood control model of the flood control protection area is further improved. According to the method, spatial variability can be planned as a whole, so that the flood risk estimation frequency and intensity of the flood control protection area are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of regional flood protection, and in particular to a method for constructing a risk map of a flood protection zone based on a global hydrodynamic model. Background Art

[0002] With climate change and urbanization, floods are increasing in frequency and intensity. Existing flood control measures, including the construction of dams, dikes, and pumping stations, were determined based on historical river flow conditions. Within flood protection zones, we identify areas requiring flood modeling and develop flood risk models for these areas.

[0003] However, currently used flood control models fail to integrate global hydrodynamic model predictions, employ a simplistic approach, and fail to account for spatial variability. Therefore, the effectiveness of specific flood protection zones in the face of global climate change and urban surface changes remains to be verified, and the accuracy of existing flood control models for these zones is low. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for constructing a flood protection zone risk map based on a global hydrodynamic model, which can solve the technical problem that the existing flood control model has low accuracy in estimating flood control models in flood protection zones.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention designs a method for constructing a flood protection zone risk map based on a global hydrodynamic model, comprising the following steps:

[0007] Select several climate models and historical reference data, and perform downscaling analysis and bias correction on the climate variables output by each climate model;

[0008] The downscaled and bias-corrected climate model is input into a global hydrological model to simulate runoff at global grid points. Runoff observation data is selected for each grid point and compared to verify the runoff data, thereby screening or combining global hydrological models.

[0009] Construct a global hydrodynamic model, input the optimized climate model and hydrological model results into the global hydrodynamic model, and conduct global hydrodynamic flood risk simulation;

[0010] Calibration of global hydrodynamic models using historical flood level statistics;

[0011] Select the optimal climate model, downscaling and bias correction methods, hydrological model, and the calibrated global hydrodynamic model to construct a long-term dynamic flood risk map;

[0012] According to the estimation results of the long-duration dynamic flood risk map, the calculation range of the flood protection zone is determined, and the long-duration dynamic flood risk map of the flood protection zone is constructed.

[0013] As a preferred solution, the global hydrodynamic model is used to study the approximate scope and trend of flood disasters, and the corresponding flood protection areas are determined based on the calculation results. The construction method of the global hydrodynamic model is as follows:

[0014] Parameters involved in the global hydrodynamic model: river water storage is S r , river depth D r , D r Determined by sea level elevation; the water storage in the floodplain is S f , floodplain water depth D f , flooded area in the floodplain A f ; Grid water storage S at the initial stage of flood ini ;S ini The calculation formula is as follows:

[0015] S ini =B ini W ini L ini ;

[0016] B ini 、W ini , L ini Corresponding to the river depth B at the initial stage of flood ini , river width W ini , River Chief L ini ;

[0017] The water storage of the next time step of the total water storage S is less than or equal to the grid water storage S at the initial flood period. ini The calculation formula of the global hydrodynamic model for the initial flood process is as follows:

[0018]

[0019] The water storage of the next time step of the total water storage S is greater than the grid water storage S at the initial flood period. ini The calculation formula of the global hydrodynamic model for the late flood retreat process is as follows:

[0020]

[0021] Where A f is the flooded area of the floodplain, which is determined by the topography, water depth of the floodplain, and water storage in the floodplain; A1 is the floodplain drainage area; D(A1) is the floodplain drainage depth; D f is the water depth in the floodplain; D(A f ) is the flood-inundated area A of the floodplain fElevation profile function at D -1 (D f ) is the floodplain elevation contour function D(A f ) is the inverse function of .

[0022] As a preferred solution, the calibration method of the global hydrodynamic model is as follows:

[0023] The flood evolution process is calculated by calculating the grid water storage of each grid, which is calculated from the grid runoff and time-shifted according to the terrain data. The global hydrodynamic model is calibrated based on the flood evolution process as follows:

[0024] Calculate the water storage S at grid point i based on the river flow i The amount of change:

[0025] Water storage S at grid point i i The change from time t to time t+Δt is expressed by the following formula:

[0026]

[0027] in, and represent the water storage of grid point i at time t and time t+Δt, respectively;

[0028] Upstream represents the total number of grid points of upstream inflow, Q k t is the inflow flow of the river (plus floodplain + bifurcation channel) from the upstream grid point k, is the sum of the inflow flows of all upstream grid points within the time Δt;

[0029] Q i t is the outflow of the river (plus floodplain + bifurcation channel) at grid point i, is the outflow rate at grid point i in time Δt;

[0030] Ac i is the unit basin area within grid point i, R i t is the input runoff at grid point i, is the inflow rate at grid point i in time Δt;

[0031] B, W, and L correspond to the river depth B, river width W, and river length L at time t, respectively;

[0032] if Then use formula (1) to calibrate the global hydrodynamic model;

[0033]

[0034] if Then use formula (2) to calibrate the global hydrodynamic model;

[0035]

[0036] The global hydrodynamic model is corrected using formulas (3) and (4).

[0037] Furthermore, the river flow is calculated based on the Saint-Venant equation:

[0038]

[0039] Where Q is the river flow (m 3 / s), A is the cross-sectional area (m 2 ), h is the fluid water depth (m), z is the riverbed bottom elevation (m), R is the hydraulic radius (m), g is the gravitational acceleration (ms -2 ), n is the Manning friction coefficient (m -1 / 3 s -1 ), the value of the Manning friction coefficient n is determined by the grid topography; x and t represent the distance and time of river flow, respectively.

[0040] Furthermore, the river cross-sectional parameters of river depth B and river width W are estimated by an empirical formula related to river flow, and other terrain parameters are determined by high-precision terrain and river network flow direction maps;

[0041]

[0042] Among them, R up Refers to the annual maximum value of the 30-day rolling average of upstream runoff.

[0043] As a preferred solution, the construction of a long-duration dynamic flood risk map for flood protection zones specifically includes the following steps:

[0044] Basic data collection and on-site investigation, data compilation and evaluation, and checking the completeness, accuracy, consistency and timeliness of data;

[0045] Hydrological analysis and calculation: Combined with the characteristics of the inflow to the flood protection zone, the flood composition analysis is carried out to determine the hydrological combination of the calculated inflow; climate model and hydrological model combination are carried out for the basin where the flood protection zone is located;

[0046] Flood analysis and calculation, corresponding to the river channel and protection area where the flood protection area is located, and calibration of the hydrodynamic model calculation parameters of the river channel and protection area;

[0047] Analyze the flood inundation range, water depth, duration and flood arrival time driven by climate patterns in the flood protection zone, and construct a long-duration dynamic flood risk map for the flood protection zone.

[0048] Beneficial effects of the present invention:

[0049] This paper provides a method for constructing a flood protection zone risk map based on a global hydrodynamic model. By incorporating the global flood model into the estimation and determination of flood protection zones, a dynamic risk model for regional flood protection zones is constructed, further improving the accuracy of flood protection zone models. By integrating the global flood model's prediction results, this method can account for spatial variability, thereby improving the frequency and intensity of flood risk estimates for flood protection zones. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the process of the present invention.

[0051] Figure 2 Schematic diagram of the global hydrodynamic model.

[0052] Figure 3 This is a schematic diagram of the long-term dynamic flood risk in the flood protection area. DETAILED DESCRIPTION

[0053] In order to make the technical solutions and advantages of the present invention more clearly understood, the present invention is further described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0054] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0055] With the advancement of computer technology, dynamic flood risk estimation models for regional flood protection zones based on global climate models have become an important tool for non-engineering flood control measures. The present invention relates to a method for constructing risk maps for flood protection zones based on a global hydrodynamic model. By incorporating a global flood model to estimate and determine flood protection zones, the present invention constructs a dynamic risk model for regional flood protection zones, further improving the accuracy of flood control models for flood protection zones. This method can account for spatial variability, thereby improving the frequency and intensity of flood risk estimates for flood protection zones.

[0056] like Figure 1As shown, the present invention provides a method for constructing a flood protection zone risk map based on a global hydrodynamic model, comprising the following steps:

[0057] Step 1: Select several climate models in CMIP6 and historical reference data, such as historical statistical data of climate variables in ECWMF.

[0058] Step 2: Downscaling analysis and bias correction are performed on the climate variables output by each climate model.

[0059] Step 3: Input the climate model after downscaling analysis and bias correction into a global hydrological model, such as SWAT and H08, to perform global grid point runoff simulation analysis, for example, the grid scale is selected as 0.25°×0.25°.

[0060] Step 4: Select runoff observation data for each grid point, such as earth2observe, to verify and compare the runoff data, so as to screen or combine the global hydrological models.

[0061] Step five: Build a global hydrodynamic model, input the optimal climate model and hydrological model results into the global hydrodynamic model, and conduct global hydrodynamic flood risk simulation.

[0062] The global hydrodynamic model is applicable to the global scale and can be used to study the approximate scope and trend of flood disasters. Based on the calculation results of the time series, the corresponding flood protection area can be determined.

[0063] The construction method of the global hydrodynamic model is as follows: The parameters involved in the global hydrodynamic model: the river water storage is S r , the water storage in the floodplain is S f , river depth D r , determined by sea level; the depth of the floodplain is D f , flooded area A f , water storage S at grid point i i , the water storage S at grid point i at the initial stage of flood ini ;

[0064] S ini The calculation formula is as follows:

[0065] S ini =B ini W ini L ini ;

[0066] B ini 、W ini 、L ini Corresponding to the river depth B at the initial stage of flood ini , river width W ini , River Chief Lini ;

[0067] The water storage of the next time step (such as one day) of the total water storage S is less than or equal to the water storage S at the grid point i during the initial flood period. ini The calculation formula of the global hydrodynamic model for the initial flood process is as follows:

[0068]

[0069] The water storage of the next time step (such as one day) for the total water storage S is greater than the storage S of the grid water i at the initial stage of the flood. ini The calculation formula of the global hydrodynamic model for the late flood retreat process is as follows:

[0070]

[0071] Where A f is the flooded area of the floodplain, which is determined by the topography, water depth of the floodplain, and water storage in the floodplain; A1 is the floodplain drainage area; D(A1) is the floodplain drainage depth; D(A f ) is the floodplain area in the flood submerged area A f Elevation profile function at D -1 (D f ) is the floodplain elevation contour function D(A f )

[0072] Step six: Use historical flood level statistics to calibrate the global hydrodynamic model.

[0073] The flood evolution process is calculated by calculating the grid water storage of each grid, which is calculated from the grid runoff and time-shifted according to the terrain data. The global hydrodynamic model is calibrated based on the flood evolution process.

[0074] Calculate the river flow Q based on the Saint-Venant equation:

[0075]

[0076] Where Q is the river flow (m 3 / s), A is the cross-sectional area (m 2 ), h is the fluid water depth (m), z is the riverbed bottom elevation (m), R is the hydraulic radius (m), g is the gravitational acceleration (ms -2 ), n is the Manning friction coefficient (m -1 / 3 s -1 ), the value of the Manning friction coefficient n is determined by the grid topography; x and t represent the distance and time of river flow, respectively;

[0077] Calculate the water storage S at grid point i based on the calculated river flow Qi The amount of change:

[0078] Water storage S at grid point i i The change from time t to time t+Δt is expressed by the following formula:

[0079]

[0080] in, and represent the water storage of grid point i at time t and time t+Δt, respectively;

[0081] Upstream represents the total number of grid points of upstream inflow, Q k t is the inflow flow of the river (plus floodplain + bifurcation channel) from the upstream grid point k, is the sum of the inflow flows of all upstream grid points within the time Δt;

[0082] Q i t is the outflow of the river (plus floodplain + bifurcation channel) at grid point i, is the outflow rate at grid point i in time Δt;

[0083] Ac i is the unit watershed area within grid point i, R i t is the input runoff at grid point i, is the inflow rate at grid point i in time Δt;

[0084] B, W, and L correspond to the river depth B, river width W, and river length L at time t, respectively. The river cross-sectional parameters, river depth B and river width W, are estimated using an empirical formula related to the river flow Q. Other terrain parameters are determined by high-precision topography and river network flow maps.

[0085]

[0086] Among them, R up Refers to the annual maximum of the 30-day rolling mean of upstream runoff. These cross-sectional parameters have significant uncertainty and require calibration before use. The above empirical formula incorporates factors such as roughness, hydraulic radius, flow rate, and longitudinal slope, requiring parameter calibration when re-simulating.

[0087] if Then use formula (1) in step 5 to calibrate the global hydrodynamic model;

[0088]

[0089] if Then use formula (2) in step 5 to calibrate the global hydrodynamic model;

[0090]

[0091] The global hydrodynamic model is corrected by formula (3) and formula (4). Figure 2 is a schematic diagram of the corrected global hydrodynamic model, where S r is the river water storage, S f is the water storage in the floodplain, D r is the river depth, D f is the water depth in the floodplain, A f is the flood-inundated area of the floodplain, D(A f ) is in floodplain A f The elevation contour function at , B is the river depth, W is the river width, L is the river length, z is the riverbed bottom elevation, A f is the flood-inundated area of the floodplain, and Ac is the unit basin area.

[0092] Step 7: For a fixed period in the future, select the optimal climate model, downscaling and bias correction method, hydrological model, and the calibrated global hydrodynamic model to construct a long-term dynamic flood risk map.

[0093] Step 8: Determine the calculation scope of the flood protection zone based on the estimated results of the long-term dynamic flood risk map.

[0094] Step nine: basic data collection and on-site investigation, collect basic data such as natural geography and hydrological data of the basin where the flood protection zone is located, river flood data, flood control project data of the protection zone, data on structures that affect the hydraulic characteristics of floods, socio-economic data, historical floods and flood disasters.

[0095] Step 10: Data compilation and evaluation: Check the data for completeness, accuracy, consistency, and timeliness. If data is insufficient, it needs to be supplemented through on-site surveys.

[0096] Step 11: Hydrological analysis and calculation. Combined with the inflow characteristics of the flood protection area, conduct flood composition analysis to determine the hydrological combination of the calculated inflow.

[0097] Step 12: Optimize the combination of climate model and hydrological model for the river basin where the flood protection area is located.

[0098] Step 13: Flood analysis and calculation. For the river channel and protected area where the flood protection zone is located, the hydrodynamic model calculation parameters of the river channel and protected area are calibrated, such as roughness and other parameters.

[0099] Step 14: Establish a two-dimensional hydrodynamic model to analyze the flood inundation range, water depth, duration and flood arrival time driven by climate patterns in the flood protection zone, and construct a long-duration dynamic flood risk map for the flood protection zone. Figure 3 The figure shows a long-duration dynamic flood risk diagram for a flood protection zone within a certain grid point.

[0100] It should be understood that the specific order or hierarchy of steps in the processes disclosed herein are examples of exemplary methods. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the processes may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0101] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for constructing a flood protection zone risk map based on a global hydrodynamic model, characterized by: The method includes the following steps: selecting several climate models and historical reference data, and performing downscaling analysis and bias correction on the climate variables output by each climate model; The downscaled and bias-corrected climate model is input into a global hydrological model to simulate runoff at global grid points. Runoff observation data is selected for each grid point and compared to verify the runoff data, thereby screening or combining global hydrological models. Construct a global hydrodynamic model, input the optimized climate model and hydrological model results into the global hydrodynamic model, and conduct global flood risk simulation; Calibration of global hydrodynamic models using historical flood level statistics; Select the optimal climate model, downscaling and bias correction methods, hydrological model, and the calibrated global hydrodynamic model to construct a long-duration dynamic flood risk map; According to the estimation results of the long-duration dynamic flood risk map, the calculation range of the flood protection zone is determined, and the long-duration dynamic flood risk map of the flood protection zone is constructed.

2. The method for constructing a flood protection zone risk map based on a global hydrodynamic model according to claim 1, characterized in that: The global hydrodynamic model is used to study the approximate scope and trend of flood disasters, and the corresponding flood protection areas are determined based on the calculation results. The construction method of the global hydrodynamic model is as follows: Parameters involved in the global hydrodynamic model: river water storage is S r , river depth D r , D r Determined by sea level elevation; the water storage in the floodplain is S f , floodplain water depth D f , flooded area in the floodplain A f ; Grid water storage S at the initial stage of flood ini ; S ini The calculation formula is as follows: S ini =B ini W ini L ini ; B ini 、W ini 、L ini Corresponding to the river depth B at the initial stage of flood ini , river width W ini , River Chief L ini ; The water storage of the next time step of the total water storage S is less than or equal to the grid water storage S at the initial flood period. ini The calculation formula of the global hydrodynamic model for the initial flood process is as follows: The water storage of the next time step of the total water storage S is greater than the grid water storage S at the initial flood period. ini The calculation formula of the global hydrodynamic model for the late flood retreat process is as follows: Where A f is the flooded area of the floodplain, which is determined by the topography, water depth of the floodplain, and water storage in the floodplain; A1 is the floodplain drainage area; D(A1) is the floodplain drainage depth; D f is the water depth in the floodplain; D(A f ) is the floodplain area in the flood submerged area A f Elevation profile function at D -1 (D f ) is the floodplain elevation contour function D(A f ) is the inverse function of .

3. The method for constructing a flood protection zone risk map based on a global hydrodynamic model according to claim 2, characterized in that: The calibration method of the global hydrodynamic model is as follows: The flood evolution process is calculated by calculating the grid water storage of each grid, which is calculated from the grid runoff and time-shifted according to the terrain data. The global hydrodynamic model is calibrated based on the flood evolution process as follows: Calculate the water storage S at grid point i based on the river flow i The amount of change: Water storage S at grid point i i The change from time t to time t+Δt is expressed by the following formula: in, and represent the water storage of grid point i at time t and time t+Δt, respectively; Upstream represents the total number of grid points of upstream inflow, Q k t is the inflow flow of the river (plus floodplain + bifurcation channel) from the upstream grid point k, is the sum of the inflow flows of all upstream grid points within the time Δt; Q i t is the outflow of the river (plus floodplain + bifurcation channel) at grid point i, is the outflow rate at grid point i in time Δt; Ac i is the unit watershed area within grid point i, is the input runoff at grid point i, is the inflow rate at grid point i in time Δt; B, W, and L correspond to the river depth B, river width W, and river length L at time t, respectively; if Then use formula (1) to calibrate the global hydrodynamic model; if Then use formula (2) to calibrate the global hydrodynamic model; The global hydrodynamic model is corrected using formulas (3) and (4).

4. The method for constructing a flood protection zone risk map based on a global hydrodynamic model according to claim 3, characterized in that: The river flow is calculated based on the Saint-Venant equation: Where Q is the river flow (m 3 Vs), A is the cross-sectional area (m 2 ), h is the fluid water depth (m), z is the riverbed bottom elevation (m), R is the hydraulic radius (m), g is the gravitational acceleration (ms -2 ), n is the Manning friction coefficient (m -1 / 3 s -1 ), the value of the Manning friction coefficient n is determined by the grid topography; x and t represent the distance and time of river flow, respectively.

5. The method for constructing a flood protection zone risk map based on a global hydrodynamic model according to claim 4, characterized in that: The river cross-sectional parameters, river depth B and river width W, are estimated by an empirical formula related to river flow, and other terrain parameters are determined by high-precision terrain and river network flow direction maps; Among them, R up Refers to the annual maximum value of the 30-day rolling average of upstream runoff.

6. The method for constructing a flood protection zone risk map based on a global hydrodynamic model according to claims 1 to 5, characterized in that: The construction of a long-term dynamic flood risk map for flood protection areas is as follows: The following steps are involved: Basic data collection and on-site investigation, data compilation and evaluation, and checking the completeness, accuracy, consistency and timeliness of data; Hydrological analysis and calculation: Combined with the characteristics of the inflow to the flood protection zone, the flood composition analysis is carried out to determine the hydrological combination of the calculated inflow; climate model and hydrological model combination are carried out for the basin where the flood protection zone is located; Flood analysis and calculation, corresponding to the river channel and protection area where the flood protection area is located, and calibration of the hydrodynamic model calculation parameters of the river channel and protection area; Analyze the flood inundation range, water depth, duration and flood arrival time driven by climate patterns in the flood protection zone, and construct a long-duration dynamic flood risk map for the flood protection zone.

Images