Flood return calculation method and simulation system based on overflow process correction

Abstract

The invention relates to the technical field of flood disaster prevention, in particular to a flood homing calculation method and simulation system based on overflow process correction. The method comprises the following steps: collecting and processing topographic data of a flood overtopping area to obtain topographic feature parameters; historical flood actual measurement data of the overtopping beach are collected, and the river channel actual measurement flood water level and flow process is obtained; according to the topographic feature parameters and the actually measured flood level process of the river channel, simulating the out-of-groove and in-groove flood processes according to the water balance principle to obtain a simulated flood overtopping flow process; and according to the flood overtopping flow process, groove returning correction is carried out on the actually-measured flood flow process of the river channel to obtain the groove-returning flood flow process of the river channel, and the groove returning flood flow process is used as the basis of groove returning flood design. By simulating the flood beach overflowing process, groove returning correction of the river flood process is achieved, the data requirement is low, flood elements are complete, and operability is high.

Description

Technical Field

[0001] The present invention relates to the technical field of flood disaster prevention, and in particular to a flood return channel calculation method and simulation system based on overflow process correction. Background Art

[0002] In flood defense and emergency management, towns and villages along the river mainly rely on building embankments to deal with floods. Although embankments effectively control floods that overflow the river channel within the river channel and ensure the flood control safety of the river bank, they also bring new problems: after the flood returns to the channel, the flood peak increases and the water level rises, thus creating new flood control risks. Therefore, in flood control planning, engineering design and flood dispatching, the impact of flood return to the channel must be fully considered to ensure overall flood control safety. Before the construction of the embankment, when the river flood enters the low-lying area of ​​the river bank (natural flood detention area), part of the water will be temporarily stored in the flood detention area; after the construction of the embankment, the river flood will return to the river channel because it cannot leave the channel, and the flood returning to the channel will raise the river water level. Therefore, with the large-scale construction of river embankments, when conducting flood control design, the impact of flood return to the channel must be considered, and the flood process after returning to the channel must be accurately calculated to provide a scientific basis for flood control planning, embankment design and flood risk assessment. However, traditional flood channeling calculation methods mainly include flood evolution method, simplified water balance method and cubic spline interpolation method. The flood evolution method is highly dependent on measured flood data and has high data requirements; the simplified water balance method can only calculate the peak flow but cannot give the flood process; the cubic spline interpolation method has a complex calculation process, large amount of calculation, and is inconvenient in practical application. These methods are difficult to meet the current flood control project requirements for flood channeling calculation accuracy and efficiency. Summary of the invention

[0003] Based on this, the present invention provides a flood return channel calculation method and simulation system based on overflow process correction to solve at least one of the above technical problems.

[0004] To achieve the above purpose, a flood return channel calculation method based on overflow process correction includes the following steps: Step S1: Acquire historical flood event data of the river; identify the flood plain area according to the historical flood event data of the river to obtain the flood plain area data of the river; determine the flood overflow elevation of the flood plain area data of the river to generate the flood overflow elevation data; draw the water level-volume curve of the detention area according to the flood overflow elevation data to generate the water level-volume curve parameters of the detention area; Step S2: Acquire historical floodplain measured flood data; perform historical flood time series processing on the historical floodplain measured flood data to obtain river channel measured flood flow process data and river channel measured flood level process data; Step S3: constructing a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; using the river channel-detention area exchange simulation model to simulate the water balance of the flood process of outflow and inflow of the river channel measured flood flow process data, and obtaining the river channel overflow flow process data; Step S4: Perform flood channel correction on the measured flood flow process data of the river channel through the river overflow flow process data to obtain channel correction river flood flow process data; this process is used as the basis for channel correction flood design.

[0005] The present invention realizes the precise identification of flood plain areas and accurately determines the flood overflow elevation through in-depth mining and analysis of historical flood event data of the river channel, and then scientifically draws the water level-volume curve of the detention area. This process fully considers the actual occurrence of historical floods. Compared with traditional methods, the present invention avoids excessive reliance on a large amount of measured flood data, reduces the difficulty and cost of data acquisition, and is particularly suitable for areas where historical data is relatively scarce. The measured flood data of historical flood plains was utilized, and through time series processing, the measured flood flow and water level process data of the river channel were obtained. Combining historical experience with modern simulation technology ensures that the calculation process can be based on real flood events, and can more accurately capture the dynamic exchange law of floods between the river channel and the detention area. A unique river channel-detention area exchange simulation model was constructed. The model is based on flood overflow elevation data, detention area water level-volume curve parameters, and river channel measured flood water level process data. The model simulates the water balance of the flood process of the measured flood flow process data of the river channel, and finally accurately calculates the river channel overflow flow process data, breaking through the limitations of traditional methods that can only calculate the peak flow or the cumbersome calculation process, and realizes the dynamic simulation of the whole process of flood return to the channel. The model can finely depict the water exchange process of floods between the detention area and the river channel, including the formation of the peak, the rise and fall of the water level in the detention area, and the speed and flow change of the flood return to the channel, thereby greatly improving the accuracy and reliability of the flood return calculation. The accurate simulation of the flood return process has been achieved, which has significantly improved the scientificity and safety of flood control project design. Therefore, compared with the existing flood return calculation methods, the flood return calculation method based on overflow process correction of the present invention has the following beneficial effects: 1) The flood evolution method requires measured flood data of multiple sessions and multiple sites under conditions of not leaving the channel and leaving the channel. The present technology innovatively proposes to correct the measured flood process by a generalized flood overflow process, and only requires the measured flood process of the studied flood in this river section and the topography of the flood detention area, and the data requirements are relatively low; 2) The simplified water balance method deduces the return to the channel flood peak flow based on the total flood volume and flood detention volume, but cannot give the flood process after returning to the channel. The present technology innovatively proposes to correct the measured flood process by a simulated flood overflow process, and the entire flood process after returning to the channel can be obtained, and the derived flood elements are complete. 3) The cubic spline interpolation method deduces the flood process after returning to the channel according to the three-spline interpolation theory, but the construction and solution process of the three-spline function is complicated and requires a lot of calculations. This technology innovatively proposes to correct the measured flood process by a simulated flood overflow process. The flood overflow process is generalized as triangles and straight lines according to the water volume. The process is mainly based on map checking and four arithmetic operations, and is highly operational.

[0006] Preferably, step S1 comprises the following steps: Step S11: Acquire historical flood event data of the river; Step S12: identifying flood plain areas according to historical flood event data of the river channel, and obtaining flood plain area data of the river channel; Step S13: performing floodplain area topography measurement based on the river flood floodplain area data to obtain floodplain area topography data; Step S14: using the floodplain area terrain data to perform terrain digital elevation model modeling to generate a river floodplain terrain digital elevation model; Step S15: determining the flood overflow elevation of the historical flood event data of the river channel through the river floodplain terrain digital elevation model to generate flood overflow elevation data; Step S16: Analyze the topographic characteristics of the detention area using the river floodplain terrain digital elevation model based on the flood overflow elevation data, draw the water level-volume curve of the detention area, and generate the water level-volume curve parameters of the detention area.

[0007] The present invention conducts topographic survey based on the identified floodplain area to obtain detailed topographic data, which reflects the geomorphic characteristics of the actual flood-affected area. Furthermore, these topographic data are used to establish a digital elevation model of the river floodplain terrain, which can display the complex terrain of the river in a high-precision three-dimensional form. By analyzing the historical flood event data, the flood overflow elevation can be accurately determined. This elevation data is a key parameter for constructing a river channel-detention area exchange simulation model, which is directly related to the accuracy of the model's simulation of the flood outflow and inflow process. The digital elevation model can also be used to analyze the topographic characteristics of the detention area, and then draw a water level-volume curve for the detention area, which reflects the relationship between the water storage capacity of the detention area and the water level.

[0008] Preferably, step S16 comprises the following steps: Step S161: using the river floodplain terrain digital elevation model to analyze the flood inundation range at different elevations on the flood overflow elevation data, and obtain flood inundation boundary data at different elevations; Step S162: Identify the flooded area of ​​the detention area according to the flood boundary data at different elevations, and generate terrain characteristic parameters—the flooded area data of the detention area at different elevations; Step S163: using the river floodplain terrain digital elevation model to discretize the terrain characteristic parameter - the flooded area data of the flood detention areas at different elevations, and generate the flood detention area micro-unit data; Step S164: Calculate the micro-unit flooding depth of the micro-unit data of the flood detention area by using the flood overflow elevation data to obtain the micro-unit flooding depth data; Step S165: Divide the water level interval according to the micro-unit flooding depth data to obtain the water level interval data of the flood detention area; Step S166: Calculating the micro-unit storage capacity of the micro-unit data of the flood detention area based on the water level interval data of the flood detention area to obtain the micro-unit storage capacity data; Step S167: Accumulate the volume of the detention area according to the micro-unit storage capacity data, and draw a water level-volume curve according to the water level interval data of the detention area to obtain the water level-volume curve parameters of the detention area.

[0009] The present invention can accurately identify the flooded area of ​​the detention area under different flood levels based on the flood inundation boundary data at different elevations, and generate terrain characteristic parameters, namely, the flooded area data of the detention area at different elevations. The detention area is discretized using a digital elevation model, and the continuous detention area is divided into multiple micro-units. This refined processing method provides smaller calculation units for subsequent calculations of the flood depth and reservoir capacity, thereby improving the calculation accuracy. The flood depth of these micro-units is calculated in combination with the flood overflow elevation data, and the flood depth of each micro-unit under a specific flood level can be accurately obtained. By dividing the micro-unit flood depth data into water level intervals, the flooding situation under different water level intervals can be obtained, which provides the necessary classification information for constructing a water level-volume curve. Based on the water level interval data, the reservoir capacity of each micro-unit is further calculated, and the micro-unit reservoir capacity data are accumulated to finally draw the water level-volume curve of the detention area. The curve intuitively shows the relationship between the water level and the water storage capacity of the detention area.

[0010] Preferably, step S2 comprises the following steps: Step S21: Obtaining historical floodplain measured flood data; Step S22: preprocessing the historical floodplain measured flood data to generate standard floodplain measured flood data; Step S23: performing historical flood time series processing on the standard floodplain measured data to generate time series floodplain measured data; Step S24: clustering the river flood process according to the measured time series floodplain flood data, and obtaining the measured river flood flow process data and the measured river flood level process data.

[0011] The present invention clusters river flood processes based on the measured data of time-series floodplains, and can effectively decompose complex flood processes to obtain the measured flood flow process data and the measured flood water level process data of the river channel. This decomposition method enables in-depth analysis of the flow and water level, respectively, and more clearly reveals the evolution characteristics of the flood in the river channel. The flow process data reflects the flow velocity and water volume changes of the flood in the river channel, while the water level process data reflects the rise and fall of the flood level. The combination of the two can fully describe the dynamic process of the flood. It realizes the effective use of historical floodplain data and extracts key flood process data, which can make fuller use of historical flood information and avoid excessive reliance on a single flood event, thereby more comprehensively reflecting the flood characteristics of the river channel.

[0012] Preferably, step S3 comprises the following steps: Step S31: using the flood overflow elevation data as the overflow water level threshold of the overflow section, using the river channel measured flood water level process data to identify the overflow time point, and obtaining the river channel flood overflow time point data; Step S32: constructing a water balance finite volume mathematical model based on the river flood overflow time point data, the river measured flood water level process data and the detention area water level-volume curve parameters to obtain a river-detention area exchange simulation model; Step S33: using the river channel-flood detention area exchange simulation model to perform water balance simulation on the flood overflow process of the river channel measured flood flow process data, and obtain the river channel overflow flow process data.

[0013] The present invention combines the river flood overflow time point data, the river measured flood water level process data and the detention area water level-volume curve parameters to construct a water balance finite volume mathematical model to form a river-detention area exchange simulation model. The model comprehensively considers the dynamic relationship between the river water level, the detention area water storage capacity and the flood overflow water volume, and realizes the accurate simulation of the flood exchange process between the river and the detention area. This not only improves the accuracy and reliability of flood return calculation, but also provides a more scientific basis for flood control project design and flood warning, thereby better protecting people's lives and property.

[0014] Preferably, step S33 includes the following steps: Step S331: Calculate the flood peak out of the channel according to the measured flood flow process data of the river channel to obtain the flood peak flow data out of the channel; wherein the flood peak calculation formula out of the channel is as follows: ; in, is the peak flow rate out of the channel, is the amount of water out of the tank, To measure the peak flood time, It is the time from the measured flood level rising to the overflow elevation; Step S332: Calculate the inflow flow according to the measured flood flow process data of the river channel to obtain the inflow flow data corresponding to the flood overflow elevation; wherein the calculation formula for the inflow flow corresponding to the flood overflow elevation is as follows: ; in, is the inflow flow corresponding to the overflow elevation, is the volume corresponding to the overflow elevation, This is the end time of this round of flooding. It is the time from the measured flood level receding to the overflow elevation; Step S333: Calculate the in-channel flood peak flow rate by using the out-channel flood peak flow rate data and the in-channel flow rate data corresponding to the flood overflow elevation, and obtain the in-channel flood peak flow rate data corresponding to the flood overflow elevation; wherein the in-channel flow rate calculation formula corresponding to the overflow elevation is as follows: ; in, is the peak flow into the channel, is the amount of water out of the tank, is the volume corresponding to the overflow elevation, is the inflow flow corresponding to the overflow elevation; Step S334: generalize the flood overflow flow process according to the river flood overflow time point data, the outflow peak flow data, the inflow flow data corresponding to the flood overflow elevation and the inflow peak flow data to obtain the river overflow flow process data.

[0015] The present invention can calculate key flood characteristic parameters, such as outflow peak flow, inflow flow and inflow peak flow, by analyzing the measured flood flow process data of the river channel. The outflow peak flow reflects the maximum flow in the outflow process of the flood, and is an important indicator for evaluating the impact of the flood on the downstream. The inflow flow represents the flow of the flood from the detention area back to the river channel, which is crucial for understanding the flood return process. The inflow peak flow is the maximum flow in the process of flood entering the channel, which reflects the release speed of the flood storage capacity of the detention area. Using the provided calculation formula, these flood characteristic parameters can be accurately calculated to provide a reliable data basis for the subsequent generalization of the flood overflow flow process. These formulas fully consider the water balance relationship and time factors in the process of flood outflow and inflow, and can more accurately reflect the dynamic change process of the flood. By comprehensively analyzing the outflow peak flow, inflow flow and inflow peak flow data, the flood overflow flow process can be generalized, and a simplified mathematical model can be established to describe the exchange process of the flood between the river channel and the detention area. This generalization method can effectively simplify the calculation process while retaining key flood characteristic information.

[0016] Preferably, step S4 is specifically: The flow process is superimposed and corrected based on the river overflow flow process data and the measured flood flow process data of the river to obtain the river flood flow process data after returning to the channel.

[0017] The present invention superimposes and corrects the river overflow flow process data with the river measured flood flow process data. In essence, it adds the flow of the flood floodplain overflow part to the measured flood flow process, thereby obtaining the river flood flow process data after returning to the channel, and distinguishes the actual flow change of the flood in the river channel from the influence of the floodplain overflow flow, so as to more accurately reflect the evolution of the flood in the river channel. Through the precise flow process superposition and correction, the simulation of the river flood flow process after returning to the channel is realized, and the reliability and scientificity of the flood return calculation are improved. The river flood flow process data after returning to the channel finally obtained provides a more accurate basis for flood control project design and flood risk assessment, and its results are of great practical significance for improving flood prevention and disaster reduction capabilities.

[0018] Preferably, the present invention further provides a flood channeling simulation system based on overflow process correction, which executes the flood channeling calculation method based on overflow process correction as described above, and the flood channeling simulation system based on overflow process correction comprises: The detention area terrain analysis module is used to obtain the historical flood event data of the river channel; identify the flood plain area according to the historical flood event data of the river channel, and obtain the flood plain area data of the river channel; determine the flood overflow elevation of the river channel flood plain area data, and generate the flood overflow elevation data; draw the water level-volume curve of the detention area according to the flood overflow elevation data, and generate the water level-volume curve parameters of the detention area; The real-time flood data processing module is used to obtain the historical flood data measured on the flood plain; the historical flood data measured on the flood plain are processed into historical flood time series to obtain the river channel measured flood flow process data and the river channel measured flood level process data; The flood flow process simulation module is used to construct a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; the river channel-detention area exchange simulation model is used to simulate the water balance of the flood process of the outflow and inflow of the river channel measured flood flow process data to obtain the river channel overflow flow process data; The flood channel correction module is used to perform flood channel correction on the measured flood flow process data of the river channel through the river overflow flow process data, and obtain the channel correction river flood flow process data; this process is used as the basis for channel flood design. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1A schematic flow chart of the steps of a flood return channel calculation method based on overflow process correction according to the present invention; Figure 2 for Figure 1 Detailed implementation steps of step S2 in the flowchart; Figure 3 for Figure 1 Detailed implementation steps of step S3 in FIG. Figure 4 It is the water level-volume curve of the flood detention reservoir basin; Figure 5 A generalized diagram of the flood overflow process; Figure 6 This is the flood process diagram after returning to the channel; The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] The technical method of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In addition, the accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. The functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor methods and / or microcontroller methods.

[0022] It should be understood that, although the terms "first", "second", etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are used only to distinguish one unit from another unit. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly the second unit may be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items.

[0023] To achieve this, please refer to Figures 1 to 3 The present invention provides a flood channel calculation method based on overflow process correction, comprising the following steps: Step S1: Acquire historical flood event data of the river; identify the flood plain area according to the historical flood event data of the river to obtain the flood plain area data of the river; determine the flood overflow elevation of the flood plain area data of the river to generate the flood overflow elevation data; draw the water level-volume curve of the detention area according to the flood overflow elevation data to generate the water level-volume curve parameters of the detention area; Step S2: Acquire historical floodplain measured flood data; perform historical flood time series processing on the historical floodplain measured flood data to obtain river channel measured flood flow process data and river channel measured flood level process data; Step S3: constructing a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; using the river channel-detention area exchange simulation model to simulate the water balance of the flood process of outflow and inflow of the river channel measured flood flow process data, and obtaining the river channel overflow flow process data; Step S4: Perform flood channel correction on the measured flood flow process data of the river channel through the river overflow flow process data to obtain channel correction river flood flow process data; this process is used as the basis for channel correction flood design.

[0024] In an embodiment of the present invention, the flood channel calculation method based on overflow process correction includes the following steps: Step S1: Acquire historical flood event data of the river; identify the flood plain area according to the historical flood event data of the river to obtain the flood plain area data of the river; determine the flood overflow elevation of the flood plain area data of the river to generate the flood overflow elevation data; draw the water level-volume curve of the detention area according to the flood overflow elevation data to generate the water level-volume curve parameters of the detention area; In an embodiment of the present invention, records of flood events that occurred in the target river section in the past are collected, including information such as the time of the flood, peak flow, water level, and inundation range. Based on these historical data, a method combining remote sensing images and digital elevation models (DEM) is used to identify flooded areas. Specifically, high-resolution remote sensing images before and after multiple flood events are selected, such as satellite images with a resolution better than 1 meter. By comparing and analyzing the changes in the range of water bodies in the images before and after the flood, combined with DEM data, the inundation range of each flood event can be extracted. For each grid cell in the floodplain area, such as a cell of 1 meter by 1 meter, its elevation value is extracted in combination with DEM data. The water level record when the grid cell is flooded in multiple flood events is compared with the elevation value of the grid cell, and the minimum value of all water level records when flooded is taken as the flood overflow elevation of the grid cell. The flood overflow elevations of all grid cells are calculated in sequence to obtain the flood overflow elevation data of the flooded floodplain area of ​​the river section. For example, if the elevation of a grid cell is 150 meters, and it is flooded when the water level reaches 151 meters, 152 meters, and 151.5 meters in three flood events, then the flood overflow elevation of the grid cell is 151 meters. Set a series of water level values, for example, from the lowest elevation to the highest elevation, and set a water level value every 0.5 meters. For each set water level value, find all grid cells below the water level value in the DEM data, and count the total area of ​​these grid cells as the flooded area under the water level. Then, use the elevation values ​​of these grid cells and the set water level values ​​to calculate the water storage capacity of each grid cell. Add up the water storage capacity of all grid cells to get the total water storage capacity under the water level. Finally, plot a series of water level values ​​and their corresponding water storage capacity into a curve, and get the water level-volume curve parameters of the flood detention area.

[0025] Step S2: Acquire historical floodplain measured flood data; perform historical flood time series processing on the historical flood plain measured flood data to obtain river channel measured flood flow process data and river channel measured flood level process data; In an embodiment of the present invention, the flood data actually observed in the target river section in the historical flood event are collected, including flow and water level data. These data are usually obtained by observation at a hydrological station, and the accuracy and reliability of the data need to be ensured, and necessary quality control is performed. The flow data are arranged in chronological order to form a flow process line. For example, in a certain flood event, the hydrological station observes the flow at 8 a.m. every day, and a series of flow data obtained are: 200 cubic meters per second on the first day, 500 cubic meters per second on the second day, 1000 cubic meters per second on the third day, 800 cubic meters per second on the fourth day, and 400 cubic meters per second on the fifth day. These data are arranged in chronological order to obtain the flow process line of the flood event. In the above-mentioned flood event, the hydrological station observes the water level at 8 a.m. every day, and a series of water level data obtained are: 149 meters on the first day, 150.5 meters on the second day, 152 meters on the third day, 151 meters on the fourth day, and 150 meters on the fifth day. These data are arranged in chronological order to obtain the water level process line of the flood event. Through time series processing, the original measured data is converted into time series data reflecting the evolution of the flood, providing a basis for subsequent simulation analysis. The interval of time series processing depends on the data sampling frequency, such as every hour, every 6 hours, every day, etc. If the sampling interval of the original data is inconsistent, interpolation processing is required to unify it to a fixed time interval.

[0026] Step S3: constructing a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; using the river channel-detention area exchange simulation model to simulate the water balance of the flood process of outflow and inflow of the river channel measured flood flow process data, and obtaining the river channel overflow flow process data; In the embodiment of the present invention, when the water level of the river channel is higher than the flood overflow elevation at the corresponding position of the detention area, the flood begins to flow out of the channel and enter the detention area; when the water level of the river channel is lower than the water level of the detention area, the detention flood body flows back into the river channel (i.e., into the channel). The measured flood water level process data of the river channel is traversed in units of a fixed time step (e.g., 1 hour). According to the measured flood water level process data of the river channel, during the period when the measured flood water level of the river channel rises, when the river channel water level rises to the flood overflow elevation, the flood begins to overflow the river channel and enter the detention area. When the measured flood peak water level is reached, the river channel flood level reaches the maximum, and the flood stops overflowing the river channel. During this period, the outflow flow rate first increases from 0 and then decreases to 0; the outflow water volume of this flood can be obtained by checking the water level-volume curve of the detention area from the measured flood peak water level; according to the time point when the flood begins to flow out of the channel, the time point when the flood peak appears, and the outflow water volume, the outflow flood flow process during the generalization period is simulated by an isosceles triangle that increases first and then decreases, and the outflow flood peak flow rate is obtained. According to the measured flood water level process data of the river channel, during the period when the measured flood water level of the river channel drops, starting from the measured flood peak water level, the river channel water level is lower than the water level of the flood detention area, and the water body of the flood detention area begins to flow into the river channel until the flood ends. During this period, the inflow flow rate increases from 0 and then decreases to 0; according to the principle of water balance, the river channel and the flood detention area exchange water, and the inflow volume is equal to the outflow volume; according to the time point of the flood peak, the time when the measured flood level recedes to the overflow elevation, the end time of this round of flood, and the inflow volume, the inflow flood flow process during the simulation period is generalized by increasing first and then decreasing, and the inflow flow and inflow peak flow corresponding to the overflow elevation are obtained. Therefore, the outflow flood flow process and the inflow flood flow process constitute the river overflow flow process data during the entire flood process.

[0027] Step S4: Perform flood channel correction on the measured flood flow process data of the river channel through the river overflow flow process data to obtain channel correction river flood flow process data; this process is used as the basis for channel correction flood design.

[0028] After the construction of the levee, the flood that originally overflowed the river channel returned to the river channel because it could not leave the channel. In an embodiment of the present invention, the measured flood flow process data of the river channel and the overflow flow process data of the river channel are aligned in time. For each time step, during the period when the measured flood water level of the river channel rises, the measured flood flow at that moment is added to the overflow flow at that moment to obtain the flood flow corrected to the channel at that moment; during the period when the measured flood water level of the river channel drops, the measured flood flow at that moment is subtracted from the overflow flow at that moment to obtain the flood flow corrected to the channel at that moment. At each time step, the measured river flow is added or subtracted from the flow overflowing to the flood detention area at that time step, that is, the river flow after returning to the channel at that time step is obtained. For example, during the period of measured flood level rise, at a certain time step, the measured river flow is 200 cubic meters / second, the overflow flow is 50 cubic meters / second, and the river flow after returning to the channel is 250 cubic meters / second; during the period of measured flood level drop, at a certain time step, the measured river flow is 180 cubic meters / second, the overflow flow is 30 cubic meters / second, and the river flow after returning to the channel is 150 cubic meters / second. By calculating the entire flood process, the complete channel correction river flood flow process data is obtained. This data reflects the change process of river flood flow after adding floodplain flood volume, which can more accurately reflect the flood discharge capacity of the river after embankment construction, and provide a more reliable basis for channel flood design. For example, the flood flow process data after channel correction can be used to re-evaluate the defense water level of river flood control projects or optimize the reservoir scheduling plan.

[0029] Preferably, step S1 comprises the following steps: Step S11: Acquire historical flood event data of the river; Step S12: identifying flood plain areas according to historical flood event data of the river channel, and obtaining flood plain area data of the river channel; Step S13: performing floodplain area topography measurement based on the river flood floodplain area data to obtain floodplain area topography data; Step S14: using the floodplain area terrain data to perform terrain digital elevation model modeling to generate a river floodplain terrain digital elevation model; Step S15: determining the flood overflow elevation of the historical flood event data of the river channel through the river floodplain terrain digital elevation model to generate flood overflow elevation data; Step S16: Analyze the topographic characteristics of the detention area using the river floodplain terrain digital elevation model based on the flood overflow elevation data, draw the water level-volume curve of the detention area, and generate the water level-volume curve parameters of the detention area.

[0030] In an embodiment of the present invention, flood event data are collected for a certain river. These data include the occurrence time of each flood, peak flow, peak water level, flood process line, and related hydrological station measured data. For example, hourly flow data of key upstream hydrological stations and hourly water level data of multiple hydrological stations along the river can be collected during each flood. Remote sensing images covering the study area before and after the flood event are collected, and high-resolution satellite images are preferred, such as satellite image data with a resolution better than 1 meter. For each flood event, at least one image before the flood and one image during or after the flood are required. The acquired remote sensing images are preprocessed, including geometric correction, radiation correction, etc., to ensure the quality and comparability of the image data. Then, supervised classification or unsupervised classification methods are used in combination with visual interpretation to extract water body information from images before and after the flood. By comparing the changes in the water body range in the images before and after the flood, the flooding range of each flood event can be determined. All identified flooding ranges are superimposed and analyzed to obtain the maximum flooding range under the influence of historical flood events, which is the flood plain area of ​​the river section. For example, three flood events flooded areas A, B, and C respectively, of which area A covers an area of ​​30 square kilometers, area B covers an area of ​​40 square kilometers, and area C covers an area of ​​25 square kilometers, and the three areas overlap partially. Through superposition analysis, the total coverage of the three areas is obtained, assuming it is 60 square kilometers, then this 60 square kilometers area is the floodplain area of ​​the river section. The output result is in vector data format. Use high-precision measuring instruments, for example, use a real-time dynamic differential positioning system (RTK) with a measurement accuracy of centimeters for field measurement. According to the area of ​​the floodplain area and the complexity of the terrain, the measurement control points and elevation points are reasonably arranged. For example, in the floodplain area, no less than 25 control points are arranged per square kilometer, the position accuracy of the control points must be better than 5 cm, and the elevation accuracy must be better than 10 cm. On the basis of the control points, the elevation points are arranged at a certain density, for example, one elevation point is arranged every 50 meters, so as to obtain the undulation of the terrain in detail. During the measurement process, it is necessary to record the plane coordinates and elevation information of each measurement point in detail and ensure the quality of the measurement data. For example, for each elevation point, record its X coordinate, Y coordinate and Z coordinate (elevation value), and make multiple measurements, and take the average value as the final elevation value. Through field measurement, high-precision terrain data covering the entire floodplain area can be obtained. The measured elevation point data is imported into the geographic information system software and spatially positioned according to its plane coordinates. Then, a suitable spatial interpolation method, such as the inverse distance weighted method or the kriging interpolation method, is selected to generate a continuous surface elevation model. For example, the kriging interpolation method is selected, and the appropriate variogram model and parameters are set according to the spatial distribution characteristics of the measured elevation data. Assume that the number of measured elevation points is 1,000 and the coverage area is 50 square kilometers.According to the spatial distribution of these elevation points, the spherical model is selected as the variogram model, and parameters such as nugget value, sill value and range are obtained according to data fitting. Using these parameters, the entire floodplain area is spatially interpolated to generate a digital elevation model in raster format. For example, a DEM with a resolution of 1 meter by 1 meter can be generated, that is, each grid cell represents an area of ​​1 meter by 1 meter on the actual ground, and the value of the grid cell represents the average elevation of the area. The generated DEM needs to be evaluated for quality. For example, the accuracy of the DEM can be verified using some measured elevation points that are not involved in the modeling to ensure that the accuracy of the DEM meets the requirements of subsequent analysis. For each DEM grid cell in the floodplain area, such as a 1 meter by 1 meter cell, it is associated with historical flood event data according to its spatial position. For each grid cell, all flood event records that have flooded the cell in history are found. For example, a grid cell was flooded in three historical flood events, and the corresponding flood water levels were 165.2 meters, 166.5 meters and 165.8 meters respectively. Compare these flood water level records with the elevation value of the grid cell, and take the minimum value of all flood water level records that flood the cell as the flood overflow elevation of the grid cell. Calculate the flood overflow elevation of all grid cells in turn to obtain the flood overflow elevation data covering the entire floodplain area. Store the flood overflow elevation data in the form of raster data, and the value of each grid cell represents the flood overflow elevation of the location. For example, a raster data with the same resolution and range as the DEM data can be generated, in which the value of each grid cell is the flood overflow elevation at that location. Treat the floodplain area as a whole flood retention area, and calculate the flooded area and corresponding water storage capacity under different water levels based on the DEM data. Set a series of water level values, for example, starting from the lowest elevation value of the DEM, and gradually increase the water level at intervals of 0.1 meters until the highest elevation value of the DEM. For each set water level value, find all grid cells in the DEM data whose elevation values ​​are lower than the water level value. Count the total area of ​​these grid cells as the flooded area under the water level. Then, calculate the water storage capacity of each flooded grid cell. The calculation method is: multiply the area of ​​the grid cell (for example, 1 square meter) by the difference between the elevation value of the grid cell and the set water level value. Add up the water storage capacity of all flooded grid cells to get the total water storage capacity at that water level. Plot all set water level values ​​and their corresponding flooded areas and water storage capacities into graphs to obtain the water level-flooded area curve and water level-volume curve of the detention area. For example, a curve can be drawn with the water level as the horizontal axis and the water storage capacity as the vertical axis. This curve clearly shows the water storage capacity of the detention area at different water levels.

[0031] Preferably, step S16 comprises the following steps: Step S161: using the river floodplain terrain digital elevation model to analyze the flood inundation range at different elevations on the flood overflow elevation data, and obtain flood inundation boundary data at different elevations; Step S162: Identify the flooded area of ​​the detention area according to the flood boundary data at different elevations, and generate terrain characteristic parameters—the flooded area data of the detention area at different elevations; Step S163: using the river floodplain terrain digital elevation model to discretize the terrain characteristic parameter - the flooded area data of the flood detention areas at different elevations, and generate the flood detention area micro-unit data; Step S164: Calculate the micro-unit flooding depth of the micro-unit data of the flood detention area by using the flood overflow elevation data to obtain the micro-unit flooding depth data; Step S165: Divide the water level interval according to the micro-unit flooding depth data to obtain the water level interval data of the flood detention area; Step S166: Calculating the micro-unit storage capacity of the micro-unit data of the flood detention area based on the water level interval data of the flood detention area to obtain the micro-unit storage capacity data; Step S167: Accumulate the volume of the detention area according to the micro-unit storage capacity data, and draw a water level-volume curve according to the water level interval data of the detention area to obtain the water level-volume curve parameters of the detention area.

[0032] In the embodiment of the present invention, a series of different elevation values ​​are selected as the basis for flood analysis. These elevation values ​​should cover the flood water level range occurring in the study area. For example, starting from the lowest flood overflow elevation, an elevation value is selected every 0.5 meters until the highest historical flood level is covered. For each selected elevation value, in the DEM data, all grid cells below the elevation value are marked as flooded areas, and all grid cells above the elevation value are marked as non-flooded areas. Then, the boundary line between the flooded area and the non-flooded area is extracted, which is the flood flood boundary corresponding to the elevation value. For example, when the selected elevation value is 165 meters, all grid cells with elevation values ​​below 165 meters are identified as flooded areas in the DEM, and the remaining grid cells are non-flooded areas. The boundary line between the flooded area and the non-flooded area is the flood flood boundary corresponding to the 165-meter elevation. The flood flood boundary corresponding to all elevation values ​​is output in the form of vector data, for example, in the Shapefile format, and the spatial position information and the corresponding elevation value attributes of each boundary line are recorded. For each flood inundation boundary corresponding to an elevation value, calculate the area of ​​the polygon enclosed by it, and this area is the flooded area of ​​the detention area corresponding to the elevation value. For example, for the flood inundation boundary corresponding to an elevation of 165 meters, use the area calculation tool in the geographic information system software to calculate the area of ​​the polygon enclosed by the boundary. Assuming it is 5 square kilometers, the flooded area of ​​the detention area corresponding to the elevation of 165 meters is 5 square kilometers. Similarly, for the flood inundation boundary corresponding to an elevation of 165.5 meters, the corresponding flooded area is calculated to be 6.2 square kilometers; for an elevation of 166 meters, the flooded area is calculated to be 7.5 square kilometers. Record all elevation values ​​and their corresponding flooded area data of the detention area in the form of a table. For example, a table containing two columns of data can be generated, the first column is the elevation value, and the second column is the flooded area of ​​the detention area corresponding to the elevation value. Divide the detention area into multiple small, regular grid units, namely micro units. The size of the micro-unit can be determined according to the resolution and calculation accuracy requirements of the DEM. For example, a grid unit of 10 meters by 10 meters can be used. For each micro-unit, determine whether it is located in the detention area based on its spatial position. The specific judgment method is: perform spatial superposition analysis on the coordinates of the center point of the micro-unit and the flooding boundaries of the detention area at different elevations. If the center point of the micro-unit is located inside the flooding boundary of a certain elevation, the micro-unit belongs to the detention area corresponding to the elevation. For example, if the center point of a micro-unit is located inside the flooding boundary at an elevation of 165 meters, the micro-unit belongs to the detention area corresponding to the elevation of 165 meters. Record the information of all micro-units belonging to the detention area, including the number of the micro-unit, the coordinates of the center point, the elevation to which it belongs, and other information. For example, a unique ID number can be assigned to each micro-unit, and the X and Y coordinates of its center point and the minimum flooding elevation to which the micro-unit belongs can be recorded.For each micro-unit in the detention area, according to the minimum inundation elevation to which it belongs, the corresponding flood overflow elevation value of the micro-unit is searched in the flood overflow elevation data. Then, the flood overflow elevation is subtracted from the minimum inundation elevation to obtain the inundation depth of the micro-unit. For example, a micro-unit belongs to the detention area corresponding to the elevation of 166 meters, and its corresponding flood overflow elevation is 165.2 meters. Then the inundation depth of the micro-unit is 166 meters minus 165.2 meters, that is, 0.8 meters. Another micro-unit belongs to the detention area corresponding to the elevation of 165.5 meters, and its corresponding flood overflow elevation is 164.8 meters. Then the inundation depth of the micro-unit is 165.5 meters minus 164.8 meters, that is, 0.7 meters. According to the inundation depth values ​​of all micro-units, the division range and interval of the water level interval are determined. For example, the water level interval can be divided into intervals of 0.1 meters between the minimum inundation depth value and the maximum inundation depth value. Record the information of all water level intervals, including the upper and lower limits of the interval. For example, a water level interval table can be generated, which contains three columns of data: interval number, interval lower limit, and interval upper limit. The table clearly defines the range of each water level interval. For each micro-unit, according to the water level interval to which it belongs, calculate the water storage capacity of the micro-unit in the water level interval, that is, the micro-unit storage capacity. For example, the area of ​​a micro-unit is 100 square meters (10 meters by 10 meters), and the water level interval to which it belongs is 0.5-0.6 meters. Then the storage capacity of the micro-unit in the water level interval is calculated as: the area of ​​the micro-unit (100 square meters) multiplied by the height of the water level interval (0.1 meter), the result is 10 cubic meters. The area of ​​another micro-unit is also 100 square meters, and the water level interval to which it belongs is 1.0-1.1 meters, so its storage capacity is also 10 cubic meters. For each water level interval, the storage capacity of all micro-units in the detention area in the water level interval is accumulated to obtain the total storage capacity of the detention area corresponding to the water level interval. The upper limit of each water level interval is taken as the water level value, and is stored in association with the corresponding total storage capacity of the detention area to form water level-volume data. The water level-volume curve of the detention area is drawn with the water level value as the horizontal coordinate and the total storage capacity of the detention area as the vertical coordinate. Then, a suitable mathematical method, such as polynomial fitting, is used to fit the water level-volume curve to obtain the parameters of the detention area water level-volume curve, such as polynomial coefficients.

[0033] Preferably, step S2 comprises the following steps: Step S21: Obtaining historical floodplain measured flood data; Step S22: preprocessing the historical floodplain measured flood data to generate standard floodplain measured flood data; Step S23: performing historical flood time series processing on the standard floodplain measured data to generate time series floodplain measured data; Step S24: clustering the river flood process according to the measured time series floodplain flood data, and obtaining the measured river flood flow process data and the measured river flood level process data.

[0034] As an example of the present invention, refer to Figure 2 As shown, Figure 1 Detailed implementation steps of step S2 in the embodiment are shown in the flowchart. In this embodiment, step S2 includes: Step S21: Obtaining historical floodplain measured flood data; In the embodiment of the present invention, data is obtained by contacting the hydrological management department, consulting the hydrological yearbook, database or related archival materials, etc. For example, a river section has experienced three flood events in history, and the hydrological management department responsible for the river section can be applied to obtain the measured data of the three flood events. Usually, the hydrological station will record the hourly or daily flow and water level data during the flood. For example, in the first flood event, the hydrological station recorded the hourly flow and water level data from the beginning to the end of the flood, including: start time, end time, hourly flow value and water level value; the second flood event recorded the daily flow and water level data; the third flood event recorded the flow and water level data every 3 hours. In the data collection process, it is necessary to ensure the integrity and accuracy of the data. For missing data, reasonable estimation or interpolation can be made based on existing data and relevant hydrological data. For example, if the flow data of some hours in a flood event is missing, it can be interpolated using a hydrological model based on the flow data of the period before and after it and the water level data of the period. At the same time, it is also necessary to verify the source and observation method of the data to ensure the reliability of the data.

[0035] Step S22: preprocessing the historical floodplain measured flood data to generate standard floodplain measured flood data; In an embodiment of the present invention, the data is checked for integrity, and missing values ​​are identified and processed. For example, if data for some time periods in a flood event are missing, they can be interpolated using methods such as linear interpolation and adjacent interpolation based on the data of the time periods before and after the time period. For missing data that cannot be reasonably interpolated, they are marked as invalid values. Secondly, the data is detected for outliers and processed. For example, outliers are identified using methods such as box plots and the 3σ principle, and the identified outliers are corrected or eliminated. For example, the flow data at a certain moment obviously deviates from the flow data of the time periods before and after, and does not match the water level data at that time, then it is an outlier and needs to be corrected or eliminated according to the actual situation. Then, the data is formatted and unified into the same format. For example, data from different sources are unified into the same unit, time format and data structure, such as unifying the flow unit into cubic meters per second, the water level unit into meters, the time format into year-month-day hour: minute: second, and the data structure into a time series data table, in which each row in the table represents a time step, and each column represents a variable (flow or water level).

[0036] Step S23: performing historical flood time series processing on the standard floodplain measured data to generate time series floodplain measured data; In an embodiment of the present invention, the target time step of the time series processing is determined. For example, 1 hour can be selected as the target time step, or other time steps, such as 30 minutes or 3 hours, can be selected according to actual needs. Then, the start time of the time series processing is determined. For example, the earliest start time of all flood events can be selected as a unified start time. According to the target time step and the start time, the data is interpolated or downsampled. For example, if the original data is recorded hourly and the target time step is 3 hours, it is necessary to downsample and select a data point every 3 hours. If the original data is recorded daily and the target time step is 1 hour, it is necessary to interpolate, for example, using a linear interpolation method, and estimate the hourly flow and water level values ​​based on the daily flow and water level data. If the time points of the original data records are not completely consistent, it is necessary to resample and interpolate the data according to the unified start time and time step. For example, if a certain time point is recorded in some flood events but not in other flood events, it is necessary to interpolate based on the existing data to estimate the flow and water level values ​​at that time point. After time series processing, time series floodplain measured data are generated. The data are arranged according to a unified time step and start time, and each time step has corresponding flow and water level data.

[0037] Step S24: clustering the river flood process according to the measured time series floodplain flood data, and obtaining the measured river flood flow process data and the measured river flood level process data.

[0038] In an embodiment of the present invention, a flow data column and a water level data column are extracted from the measured data of the time series floodplain. For example, data columns representing the flow and the water level are extracted from the time series data table. Then, cluster analysis is performed on the flow data column and the water level data column to identify different flood processes. The K-means clustering algorithm can be used to divide the flow data into different categories according to the size and change trend of the flow data, and each category represents a flood process. For example, the flow data can be divided into three categories, representing three different flood processes, respectively. The first category has a small flow and a short duration; the second category has a large flow and a long duration; and the third category has a flow between the two. Similarly, the water level data can be clustered and divided into different categories according to the size and change trend of the water level data. According to the clustering results, the flow data and the water level data are organized into independent data sets, namely, the river channel measured flood flow process data and the river channel measured flood water level process data. For example, two data tables can be generated, one data table contains the flow data of all flood processes, each row represents a time step, and each column represents the flow data of a flood process; the other data table contains the water level data of all flood processes, each row represents a time step, and each column represents the water level data of a flood process.

[0039] Preferably, step S3 comprises the following steps: Step S31: using the flood overflow elevation data as the overflow water level threshold of the overflow section, using the river channel measured flood water level process data to identify the flood overflow time point, and obtaining the river channel flood overflow time point data; Step S32: constructing a water balance finite volume mathematical model based on the river flood overflow time point data, the river measured flood water level process data and the detention area water level-volume curve parameters to obtain a river-detention area exchange simulation model; Step S33: using the river channel-flood detention area exchange simulation model to perform water balance simulation on the flood overflow process of the river channel measured flood flow process data, and obtain the river channel overflow flow process data.

[0040] As an example of the present invention, refer to Figure 2 As shown, Figure 1 Detailed implementation steps of step S3 in the flowchart, in this example, step S3 includes: Step S31: using the flood overflow elevation data as the overflow water level threshold of the overflow section, using the river channel measured flood water level process data to identify the flood overflow time point, and obtaining the river channel flood overflow time point data; In the embodiment of the present invention, for each river section, the flood overflow elevation data obtained in step S1 is used as the overflow water level threshold of the section. The measured flood water level process data of the river obtained in step S2 is used to identify the start time of the flood floodplain. Specifically, the water level process data is compared with the overflow water level threshold. When the water level exceeds the threshold, the time point is recorded as the start time of the floodplain.

[0041] Step S32: constructing a water balance finite volume mathematical model based on the river flood overflow time point data, the river measured flood water level process data and the detention area water level-volume curve parameters to obtain a river-detention area exchange simulation model; In the embodiment of the present invention, when the water level of the river channel is higher than the flood overflow elevation at the corresponding position of the detention area, the flood begins to flow out of the channel and enter the detention area; when the water level of the river channel is lower than the water level of the detention area, the detention flood body flows back into the river channel (i.e., into the channel). Among them, when the water level of the river channel rises to the measured peak water level, the water level of the river channel and the detention area are flush, the water out of the channel reaches the maximum, and the flood will turn from out of the channel to into the channel. The water out of the channel of this flood can be obtained by checking the water level-volume curve of the detention area from the measured peak water level. There is an exchange of water in and out of the channel between the river channel and the detention area. According to the principle of water balance, the flood volume in the channel is equal to the flood volume out of the channel, thereby obtaining a river channel-detention area exchange simulation model.

[0042] Step S33: using the river channel-flood detention area exchange simulation model to perform water balance simulation on the flood overflow process of the river channel measured flood flow process data, and obtain the river channel overflow flow process data.

[0043] The measured flood water level process data of the river channel is traversed in units of a fixed time step (for example, 1 hour). According to the measured flood water level process data of the river channel, during the period of the measured flood water level rise in the river channel, when the river water level rises to the flood overflow elevation, the flood begins to overflow the river channel and enters the flood detention area. When the measured flood peak water level reaches the flood overflow level, the flood stops overflowing the river channel. During this period, the outflow flow rate first increases from 0 and then decreases to 0. According to the time point when the flood begins to flow out of the channel, the time point when the flood peak appears, and the outflow water volume, the outflow flood flow process during the generalization period is simulated according to an isosceles triangle that increases first and then decreases, and the outflow peak flow rate is obtained. According to the measured flood water level process data of the river channel, during the period when the measured flood water level of the river channel dropped, starting from the measured flood peak water level, the river channel water level was lower than the water level of the flood detention area, and the flood detention body began to flow into the river channel until the flood ended. During this period, the inflow into the channel increased from 0 and then decreased to 0; according to the time point of the flood peak, the time when the measured flood level receded to the overflow elevation, the time when this round of flood ended, and the amount of water entering the channel, the inflow into the channel flood flow process during the generalization period was simulated by increasing first and then decreasing, and the inflow into the channel flow and the inflow into the channel flood peak flow corresponding to the overflow elevation were obtained. Therefore, the outflow flood flow process and the inflow flood flow process constitute the river overflow flow process data during the entire flood process.

[0044] Preferably, step S33 includes the following steps: Step S331: Calculate the flood peak out of the channel according to the measured flood flow process data of the river channel to obtain the flood peak flow data out of the channel; wherein the flood peak calculation formula out of the channel is as follows: ; in, is the peak flow rate out of the channel, is the amount of water out of the tank, To measure the peak flood time, It is the time from the measured flood level rising to the overflow elevation; Step S332: Calculate the inflow flow according to the measured flood flow process data of the river channel to obtain the inflow flow data corresponding to the flood overflow elevation; wherein the calculation formula of the inflow flow corresponding to the flood overflow elevation is as follows: ; in, is the inflow flow corresponding to the overflow elevation, is the volume corresponding to the overflow elevation, This is the end time of this round of flooding. It is the time from the measured flood level receding to the overflow elevation; Step S333: Calculate the in-channel flood peak flow rate by using the out-channel flood peak flow rate data and the in-channel flow rate data corresponding to the flood overflow elevation, and obtain the in-channel flood peak flow rate data corresponding to the flood overflow elevation; wherein the in-channel flow rate calculation formula corresponding to the overflow elevation is as follows: ; in, is the peak flow into the channel, is the amount of water out of the tank, is the volume corresponding to the overflow elevation, is the inflow flow corresponding to the overflow elevation; Step S334: generalize the flood overflow flow process according to the river flood overflow time point data, the outflow peak flow data, the inflow flow data corresponding to the flood overflow elevation and the inflow peak flow data to obtain the river overflow flow process data.

[0045] In the embodiment of the present invention, the required parameters are extracted from the measured flood flow process data and water level process data of the river acquired in step S2. It represents the time when the measured peak flow occurs, which can be determined by finding the time corresponding to the maximum value in the flow process data. It represents the time when the measured flood level rises to the overflow elevation, which can be determined by finding the time when the water level first reaches or exceeds the overflow elevation in the water level process data. represents the outflow water volume, that is, the total amount of water flowing from the river into the flood detention area during the floodplain, which can be estimated by the method of step S32. Substituting these parameters into the outflow flood peak calculation formula: Based on the selected typical flood event, the required parameters are extracted from the measured flood flow process data and water level process data of the river obtained in step S2. It represents the end time of this round of flood, that is, the time point when the water level process drops back to the base flow level. It represents the time for the measured flood level to recede to the overflow elevation, which can be determined by finding the time for the water level in the water level process data to fall from above the overflow elevation to equal to or below the overflow elevation. The volume of the detention area corresponding to the overflow elevation can be calculated by using the detention area water level-volume curve obtained in step S1 by substituting the overflow elevation into the curve equation. Substituting these parameters into the calculation formula for the inlet flow corresponding to the overflow elevation: ; Use the results calculated in the previous steps to calculate the peak flow into the slot. is the amount of water discharged from the tank calculated in step S331, It is the volume corresponding to the overflow elevation, that is, the volume below the overflow elevation, which can be calculated by substituting the overflow elevation into the water level-volume curve of the detention area. and They are respectively the time for the water level to recede to the overflow elevation in step S332 and step S331 and the time when the measured flood peak occurs. is the inflow flow corresponding to the overflow elevation calculated in step S332. Substitute these parameters into the inflow peak flow calculation formula: . According to the outflow peak flow, the inflow peak flow corresponding to the flood overflow elevation, the inflow peak flow, as well as the outflow time, the peak time and the inflow time, the actual flood overflow flow process is generalized into a triangle or trapezoid. For example, for section A, the outflow peak flow is 617.28 cubic meters per second, which occurs in the third hour; the inflow peak flow is 461.56 cubic meters per second, which occurs in the fifth hour; the inflow flow corresponding to the flood overflow elevation is 257.20 cubic meters per second, which occurs in the seventh hour. The overflow flow process can be generalized into a trapezoid, the upper base of the trapezoid is the inflow peak flow, the lower base is the inflow flow corresponding to the flood overflow elevation, the left rising section is the outflow stage, and the right descending section is the inflow stage. The generalized overflow flow process is used as an input condition and input into the river channel-flood retention area exchange simulation model constructed in step S33. In each time step, the model calculates the water exchange between the river and the detention area based on the current river water level, the detention area water level, and the generalized overflow flow process. By simulating the entire flood process, the actual overflow flow of each section in each time step can be obtained. By arranging these flow data in chronological order, the river overflow flow process data can be obtained.

[0046] Preferably, step S4 is specifically: The flow process is superimposed and corrected based on the river overflow flow process data and the measured flood flow process data of the river to obtain the river flood flow process data after returning to the channel.

[0047] In an embodiment of the present invention, it is ensured that the time steps of the river overflow flow process data and the river measured flood flow process data are consistent, for example, both are in step length of 1 hour. If the time steps are inconsistent, interpolation processing is required to unify the time steps. Create a new time series whose time step is consistent with the input data, which is used to store the river flood flow process data after returning to the channel. Perform the following operations for each time step: 1. Determine the overflow flow direction: judge the relative size of the river water level and the flood detention area water level at this time step. If the river water level is higher than the flood detention area water level, the overflow flow direction is from the river to the flood detention area (positive value); if the river water level is lower than the flood detention area water level, the overflow flow direction is from the flood detention area back to the river (negative value). The overflow flow calculated in S3 is based on the river channel, and a positive value indicates that water flows out of the river channel, and a negative value indicates that water flows back to the river channel. 2. Calculate the return channel flow: superimpose the measured flood flow of the river channel with the overflow flow of this time step. The overflow flow is positive, indicating that water flows out of the river channel, reducing the river flow, so it needs to be added when calculating the river flow after returning to the channel; the overflow flow is negative, indicating that water flows back into the river channel, increasing the river flow, so it needs to be subtracted when calculating the flow after returning to the channel. The calculation formula is as follows: Return to the channel flow = measured flow + overflow flow. The return to the channel flow calculated at each time step is arranged in chronological order to form a complete river flood flow process data after returning to the channel. This data more accurately reflects the change process of river flood flow after adding floodplain flood volume or adding return flow, and can more accurately reflect the actual flood discharge capacity of the river channel, providing a more reliable basis for the design of return to the channel flood. For example, the flood flow process data after the correction of the return to the channel can be used to re-evaluate the defense level of the river flood control project or optimize the scheduling plan of the reservoir.

[0048] Preferably, the present invention further provides a flood channeling simulation system based on overflow process correction, which executes the flood channeling calculation method based on overflow process correction as described above, and the flood channeling simulation system based on overflow process correction comprises: The detention area terrain analysis module is used to obtain the historical flood event data of the river channel; identify the flood plain area according to the historical flood event data of the river channel, and obtain the flood plain area data of the river channel; determine the flood overflow elevation of the river channel flood plain area data, and generate the flood overflow elevation data; draw the water level-volume curve of the detention area according to the flood overflow elevation data, and generate the water level-volume curve parameters of the detention area; The real-time flood data processing module is used to obtain the historical flood data measured on the flood plain; the historical flood data measured on the flood plain are processed into historical flood time series to obtain the river channel measured flood flow process data and the river channel measured flood level process data; The flood flow process simulation module is used to construct a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; the river channel-detention area exchange simulation model is used to simulate the water balance of the flood process of the outflow and inflow of the river channel measured flood flow process data to obtain the river channel overflow flow process data; The flood channel correction module is used to perform flood channel correction on the measured flood flow process data of the river channel through the river overflow flow process data, and obtain the channel correction river flood flow process data; this process is used as the basis for channel flood design.

[0049] Preferably, see Figure 4 , which is the water level-volume curve of the flood detention basin. The flood detention area serves as a flood detention basin. The basin mouth elevation H basin mouth when the flood begins to flood the beach can be found from the topographic data, and the relationship curve H~V between the reservoir basin water level and volume can be measured. The volume V basin mouth corresponding to H basin mouth can be found from the H~V curve.

[0050] Preferably, see Figure 5 , which is a generalized diagram of the flood overflow process. During the flood rising stage measured in the river channel, when the flood level rises to the H basin mouth, the flood begins to flow out of the river channel until the peak water level , the flow rate was stopped during the measurement, and the flow rate increased first and then decreased. The time from the flooding to the H basin mouth , when the flood peak occurs The outflow volume Voutflow is generalized as an isosceles triangle that increases first and then decreases ~ The flood discharge process during the period can be used to obtain the peak flow of the channel. , out of the channel, river channel measured flood retreat stage, flood peak water level After the actual measurement, the floodwaters in the floodplain began to flow into the river channel, and the flow rate increased first and then decreased. When the flood water level retreated to the mouth of the H basin, the flow rate gradually decreased. The time from the retreat to the mouth of the H basin was , when this round of floods will end , the volume V basin mouth corresponding to the H basin mouth is gradually reduced and linearly generalized ~ During the flood process, the inflow flow corresponding to the basin mouth elevation is , and then by , , the remaining water volume in the trough V out of the trough - V basin mouth and , basin mouth, first increase and then decrease to , the process of basin mouth, linear, equidistant generalization ~ During the flood process, the maximum flow rate is , into the slot.

[0051] Preferably, see Figure 6 , is the flood process diagram after returning to the channel, for the measured river flood process, ~ The measured flow during the flood period plus the outflow flood flow during the same period, ~ , ~ The measured flow during the water withdrawal period minus the flood flow during the same period can be used to obtain the flood process after returning to the channel and the flood peak flow after returning to the channel. , return to the groove.

[0052] The present application is to accurately determine the flood overflow elevation by deeply analyzing the historical flood event data of the river channel, combining the flood floodplain area identification and topographic measurement technology, and scientifically draw the water level-volume curve of the detention area, making full use of the existing topographic data and historical flood information, avoiding excessive reliance on a large amount of measured flood data, reducing the difficulty and cost of data acquisition, and is particularly suitable for areas where historical data is relatively scarce. Compared with the traditional flood evolution method, the present invention does not require measured flood data of multiple sessions and multiple sites. It only needs to study the measured flood process of the river section and the topography of the detention area to achieve accurate simulation of the flood return process, significantly improving the applicability and operability of flood return calculation. The river channel-detention area exchange simulation model based on the water balance principle can finely simulate the dynamic exchange process of floods between the river channel and the detention area. The model comprehensively considers the flood overflow elevation, the water level-volume relationship of the detention area, and the measured flood water level process data of the river channel, and accurately calculates the river channel overflow flow process data through the water balance simulation of the flood process of the outflow and inflow. Compared with the simplified water balance method, the present invention can not only deduce the flood peak flow after returning to the channel, but also obtain the complete flood process after returning to the channel. The derived flood elements are complete, providing more comprehensive flood characteristic information for flood control project design. In the calculation process, a simplified flood overflow flow process generalization method is adopted, which is mainly based on map query and four arithmetic operations, avoiding complex mathematical modeling and tedious calculation process. Compared with the cubic spline interpolation method, the calculation process of the present invention is more efficient and concise, the amount of calculation is greatly reduced, the operability is strong, and the flood flow process data after returning to the channel can be quickly generated, providing timely technical support for flood control decision-making and emergency response.

[0053] Therefore, the embodiments should be regarded as illustrative and non-restrictive from all points, and the scope of the present invention is limited by the appended claims rather than the above description, and it is therefore intended that all changes falling within the meaning and range of equivalent elements of the application documents are included in the present invention.

[0054] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features invented herein.

Claims

1. A flood channel calculation method based on overflow process correction, characterized in that: The following steps are involved: Step S1: Obtain historical flood event data of the river; Flood floodplain areas are identified based on historical flood event data of the river channel to obtain flood floodplain area data of the river channel; flood overflow elevations are determined for the flood floodplain area data of the river channel to generate flood overflow elevation data; water level-volume curves of the detention area are drawn based on the flood overflow elevation data to generate water level-volume curve parameters of the detention area; Step S2: Acquire historical floodplain measured flood data; perform historical flood time series processing on the historical floodplain measured flood data to obtain river channel measured flood flow process data and river channel measured flood level process data; Step S3: constructing a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; using the river channel-detention area exchange simulation model to simulate the water balance of the flood process of outflow and inflow of the river channel measured flood flow process data, and obtaining the river channel overflow flow process data; Step S4: performing flood channel correction on the measured flood flow process data of the river channel using the river overflow flow process data to obtain channel correction river flood flow process data; This process is used as the basis for the design of channel flood.

2. The flood channel calculation method based on overflow process correction according to claim 1 is characterized in that: Step S1 includes the following steps: Step S11: Acquire historical flood event data of the river; Step S12: identifying flood plain areas according to historical flood event data of the river channel, and obtaining flood plain area data of the river channel; Step S13: performing floodplain area topography measurement based on the river flood floodplain area data to obtain floodplain area topography data; Step S14: using the floodplain area terrain data to perform terrain digital elevation model modeling to generate a river floodplain terrain digital elevation model; Step S15: determining the flood overflow elevation of the historical flood event data of the river channel through the river floodplain terrain digital elevation model to generate flood overflow elevation data; Step S16: Analyze the topographic characteristics of the detention area using the river floodplain terrain digital elevation model based on the flood overflow elevation data, draw the water level-volume curve of the detention area, and generate the water level-volume curve parameters of the detention area.

3. The flood channel calculation method based on overflow process correction according to claim 2 is characterized in that: Step S16 includes the following steps: Step S161: using the river floodplain terrain digital elevation model to analyze the flood inundation range at different elevations on the flood overflow elevation data, and obtain flood inundation boundary data at different elevations; Step S162: Identify the flooded area of ​​the detention area according to the flood boundary data at different elevations, and generate terrain characteristic parameters—the flooded area data of the detention area at different elevations; Step S163: using the river floodplain terrain digital elevation model to discretize the terrain characteristic parameter - the flooded area data of the flood detention areas at different elevations, and generate the flood detention area micro-unit data; Step S164: Calculate the micro-unit flooding depth of the micro-unit data of the flood detention area by using the flood overflow elevation data to obtain the micro-unit flooding depth data; Step S165: Divide the water level interval according to the micro-unit flooding depth data to obtain the water level interval data of the flood detention area; Step S166: Calculating the micro-unit storage capacity of the micro-unit data of the flood detention area based on the water level interval data of the flood detention area to obtain the micro-unit storage capacity data; Step S167: Accumulate the volume of the detention area according to the micro-unit storage capacity data, and draw a water level-volume curve according to the water level interval data of the detention area to obtain the water level-volume curve parameters of the detention area.

4. The flood channel calculation method based on overflow process correction according to claim 1 is characterized in that: Step S2 includes the following steps: Step S21: Obtaining historical floodplain measured flood data; Step S22: preprocessing the historical floodplain measured flood data to generate standard floodplain measured flood data; Step S23: performing historical flood time series processing on the standard floodplain measured data to generate time series floodplain measured data; Step S24: clustering the river flood process according to the measured time series floodplain flood data, and obtaining the measured river flood flow process data and the measured river flood level process data.

5. The flood channel calculation method based on overflow process correction according to claim 1 is characterized in that: Step S3 includes the following steps: Step S31: using the flood overflow elevation data as the overflow water level threshold of the overflow section, using the river channel measured flood water level process data to identify the flood overflow time point, and obtaining the river channel flood overflow time point data; Step S32: constructing a water balance finite volume mathematical model based on the river flood overflow time point data, the river measured flood water level process data and the detention area water level-volume curve parameters to obtain a river-detention area exchange simulation model; Step S33: using the river channel-flood detention area exchange simulation model to perform water balance simulation on the flood overflow process of the river channel measured flood flow process data, and obtain the river channel overflow flow process data.

6. The flood channel calculation method based on overflow process correction according to claim 5 is characterized in that: Step S33 includes the following steps: Step S331: Calculate the flood peak out of the channel according to the measured flood flow process data of the river channel to obtain the flood peak flow data out of the channel; wherein the flood peak calculation formula out of the channel is as follows: ； in, is the peak flow rate out of the channel, is the amount of water out of the tank, To measure the peak flood time, It is the time from the measured flood level rising to the overflow elevation; Step S332: Calculate the inflow flow according to the measured flood flow process data of the river channel to obtain the inflow flow data corresponding to the flood overflow elevation; wherein the calculation formula for the inflow flow corresponding to the flood overflow elevation is as follows: ； in, is the inflow flow corresponding to the overflow elevation, is the volume corresponding to the overflow elevation, This is the end time of this round of flooding. It is the time from the measured flood level receding to the overflow elevation; Step S333: Calculate the in-channel flood peak flow rate by using the out-channel flood peak flow rate data and the in-channel flow rate data corresponding to the flood overflow elevation, and obtain the in-channel flood peak flow rate data corresponding to the flood overflow elevation; wherein the in-channel flow rate calculation formula corresponding to the overflow elevation is as follows: ； in, is the peak flow into the channel, is the amount of water out of the tank, is the volume corresponding to the overflow elevation, is the inflow flow corresponding to the overflow elevation; Step S334: generalize the flood overflow flow process according to the river flood overflow time point data, the outflow peak flow data, the inflow flow data corresponding to the flood overflow elevation and the inflow peak flow data to obtain the river overflow flow process data.

7. The flood channel calculation method based on overflow process correction according to claim 1 is characterized in that: Step S4 is specifically as follows: The flow process is superimposed and corrected based on the river overflow flow process data and the measured flood flow process data of the river to obtain the river flood flow process data after returning to the channel.

8. A flood channel simulation system based on overflow process correction, characterized in that: Used to execute the flood channeling calculation method based on overflow process correction as claimed in claim 1, the flood channeling simulation system based on overflow process correction comprises: The detention area terrain analysis module is used to obtain the historical flood event data of the river channel; identify the flood plain area according to the historical flood event data of the river channel, and obtain the flood plain area data of the river channel; determine the flood overflow elevation of the river channel flood plain area data, and generate the flood overflow elevation data; draw the water level-volume curve of the detention area according to the flood overflow elevation data, and generate the water level-volume curve parameters of the detention area; The real-time flood data processing module is used to obtain the historical flood data measured on the flood plain; the historical flood data measured on the flood plain are processed into historical flood time series to obtain the river channel measured flood flow process data and the river channel measured flood level process data; The flood flow process simulation module is used to construct a river channel-detention area exchange simulation model based on flood overflow elevation data, detention area water level-volume curve parameters and river channel measured flood level process data; the river channel-detention area exchange simulation model is used to simulate the water balance of the flood process of the outflow and inflow of the river channel measured flood flow process data to obtain the river channel overflow flow process data; The flood channel correction module is used to perform flood channel correction on the measured flood flow process data of the river channel through the river overflow flow process data, and obtain the channel correction river flood flow process data; this process is used as the basis for channel flood design.

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