A method for calculating reservoir rainwater carrying capacity based on dynamic runoff coefficient

Abstract

This invention relates to the fields of reservoir scheduling, flood control and disaster reduction, and hydrological forecasting, and particularly to a method for calculating reservoir rainfall carrying capacity based on a dynamic runoff coefficient. The method includes the following steps: collecting data including the target reservoir's catchment area, characteristic water level, and water level-capacity relationship curves; establishing a dynamic equation for rainfall-runoff coefficient based on reservoir storage using the initial water level, characteristic water level, and storage capacity relationship curves; collecting and analyzing historical flood data for the target reservoir to generate parameter statistics tables for each flood event; establishing a dynamic equation for rainfall-runoff coefficient based on underlying surface conditions based on the parameter statistics tables for each flood event; and solving the dynamic equations based on reservoir storage and underlying surface conditions simultaneously. This invention relies on real-time water level and real-time rainfall to dynamically calculate reservoir rainfall carrying capacity, thus improving the accuracy of reservoir rainfall carrying capacity calculation.

Description

Technical Field

[0001] This invention relates to the fields of reservoir scheduling, flood control and disaster reduction and hydrological forecasting, and in particular to a method for calculating the rain-carrying capacity of a reservoir based on a dynamic runoff coefficient. Background Technology

[0002] In existing technologies, the calculation of reservoir rainfall carrying capacity typically uses a static runoff coefficient, meaning the runoff coefficient is fixed during the calculation process. This method has a significant drawback: as rainfall continues, the soil moisture content in the watershed constantly changes, leading to a significant difference between the actual runoff and the preset fixed runoff coefficient. This causes the calculated rainfall carrying capacity to deviate from reality, making it difficult to accurately reflect the reservoir's true rainfall carrying capacity. This limits the accuracy and timeliness of reservoir scheduling and flood warnings, hindering the scientific and effective nature of flood control decisions. Summary of the Invention

[0003] Therefore, it is necessary for the present invention to provide a method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient, in order to solve at least one of the above-mentioned technical problems.

[0004] To achieve the above objectives, a method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient includes the following steps: Step S1: Collect data including the target reservoir's catchment area, characteristic water level, and water level-reservoir capacity relationship curve; use the characteristic water level and reservoir capacity relationship curve to establish a dynamic equation for rainfall-runoff coefficient based on the reservoir's water storage. Step S2: Collect historical flood data of the target reservoir and analyze the data to generate a parameter statistical table for each flood event; establish a dynamic equation for rainfall-runoff coefficient based on underlying surface conditions according to the parameter statistical table for each flood event. Step S3: Solve the dynamic equations of rainfall-runoff coefficient based on reservoir storage and rainfall-runoff coefficient based on underlying surface conditions using MATLAB programming, and establish a lookup table of rainwater carrying capacity and runoff coefficient based on the intersection points in the solution.

[0005] This application, on the one hand, establishes... The empirical relationship and dynamic updating of the runoff coefficient fully reflect the impact of soil moisture content changes on the runoff generation process, making the calculation of rainwater carrying capacity closer to actual hydrological conditions. On the other hand, by pre-generating lookup tables, the current rainwater carrying capacity and runoff coefficient can be quickly obtained based on real-time water levels and previous rainfall, supporting dynamic scheduling and real-time early warning during the flood season. Furthermore, based on a general hydrological model and water balance principle, this application can be widely applied to various types of reservoirs, especially small and medium-sized reservoirs lacking real-time hydrological forecasts. In addition, the table creation and lookup method reduces computational complexity, facilitating promotion and application. Moreover, this application integrates physical mechanisms and statistical experience, ensuring the theoretical foundation of the model while enhancing its applicability and stability in practical scenarios. Attached Figure Description

[0006] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the steps of a method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient according to the present invention. Figure 2 This is a schematic diagram of the dynamic equation of rainfall-runoff coefficient based on reservoir storage in an embodiment of the present invention; Figure 3 This is a schematic diagram of the dynamic equation of rainfall-runoff coefficient based on underlying surface conditions in an embodiment of the present invention; Figure 4 This is a schematic diagram of the intersection points in the solution process of this invention embodiment; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0007] The technical method of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0008] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0009] 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 merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0010] To achieve the above objectives, please refer to Figures 1 to 4 This invention provides a method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient. The method includes the following steps: Step S1: Collect data including the target reservoir's catchment area, characteristic water level, and water level-reservoir capacity relationship curve; use the characteristic water level and reservoir capacity relationship curve to establish a dynamic equation for rainfall-runoff coefficient based on the reservoir's water storage. Step S2: Collect historical flood data of the target reservoir and analyze the data to generate a parameter statistical table for each flood event; establish a dynamic equation for rainfall-runoff coefficient based on underlying surface conditions according to the parameter statistical table for each flood event. Step S3: Solve the dynamic equations of rainfall-runoff coefficient based on reservoir storage and rainfall-runoff coefficient based on underlying surface conditions using MATLAB programming, and establish a lookup table of rainwater carrying capacity and runoff coefficient based on the intersection points in the solution.

[0011] Optionally, step S3 may be followed by: Obtain the rainfall data of the target reservoir and the initial water level of the target reservoir at the target time, and use the rainfall data of the target reservoir to calculate the antecedent rainfall at the target time; Based on the initial water level of the target reservoir at the target time and the preceding impact rainfall at the target time, a lookup table for the rain-carrying capacity and runoff coefficient is used to obtain the rain-carrying capacity and runoff coefficient of the target reservoir at the target time.

[0012] In one embodiment, when it is necessary to calculate the reservoir's rainfall carrying capacity and the runoff coefficient of upstream water at a certain moment, the initial water level of the reservoir at that moment is queried. The rainfall data from the reservoir was used to calculate the amount of rainfall that had an impact in the early stages. According to the current situation and By querying the generated table of rainwater carrying capacity and runoff coefficient, you can obtain the rainwater carrying capacity of the reservoir and the runoff coefficient of the upstream water at that moment.

[0013] It is worth noting that, Figure 4 In That is, the aforementioned .

[0014] Optionally, step S1 includes: Step S11: Collect data including the target reservoir's catchment area, characteristic water levels, and water level-reservoir capacity relationship curves; where the characteristic water levels include the reservoir's flood control limit water level, design water level, and check water level; Step S12: Compare the water level-reservoir capacity relationship curve with the characteristic water level to calculate the reservoir capacity difference between different initial water levels and characteristic water levels; Step S13: Establish a dynamic equation for rainfall-runoff coefficient based on reservoir storage by using the preset reservoir water balance equation and based on characteristic parameters and the difference in reservoir capacity between different initial water levels and characteristic water levels.

[0015] In one embodiment, the catchment area of ​​a reservoir is collected by using hydrological stations near the reservoir or by consulting relevant materials. 212 The flood control limit water level is 180m (in this embodiment, the characteristic water level is taken as the flood control limit water level). The reservoir capacity relationship curve is shown in the table below: Subsequently, the reservoir capacity difference between different water levels and the flood control limit level was calculated, as shown in the table below: Furthermore, according to the reservoir water balance equation, To obtain different Corresponding and The curve representing the relationship, i.e., the dynamic equation of rainfall-runoff coefficient based on reservoir storage. The dynamic equation for rainfall-runoff coefficient based on reservoir storage is as follows: Figure 2 As shown; where Figure 2 The rain-holding capacity mentioned above refers to the average total rainfall. .

[0016] It is worth noting that the average total rainfall The method for obtaining the data is to collect the average value of the measured rainfall at each rain gauge station in the basin near the reservoir during the corresponding time period, and then perform time-series summation on the target time period.

[0017] Optionally, step S2 includes: Step S21: Collect historical flood data for the target reservoir; Step S22: Based on the water and rainfall data, calculate the average total rainfall, the amount of rainfall affecting the preceding flood, the total runoff depth, and the surface runoff depth for each flood event, thereby generating a parameter statistical table for each flood event; Step S23: Substitute the average total rainfall and surface runoff depth corresponding to each flood in the parameter statistics table of each flood into the preset SCS model relationship to calculate the maximum possible retention flow of the watershed at that time for each flood. Step S24: Establish the correspondence between the maximum possible retention capacity and the previous impact rainfall for each flood event, and use the previous impact rainfall as the independent variable and the maximum possible retention capacity as the dependent variable to fit the changing trend between the independent and dependent variables, so as to construct the correlation curve between the previous impact rainfall and the maximum possible retention capacity. Step S25: Establish the correlation curve between surface runoff coefficient and total runoff coefficient based on the parameter statistics table of each flood event; Step S26: Based on the correlation curves of previous impact rainfall ~ maximum possible retention flow and surface runoff coefficient ~ total runoff coefficient, derive the dynamic equation of rainfall ~ runoff coefficient based on underlying surface conditions.

[0018] In this embodiment, historical flood data from the target reservoir or nearby hydrological stations are collected, and then the flood data for each event is analyzed to generate data on rainfall, surface runoff depth, and antecedent rainfall for each event. Surface runoff coefficient Total runoff coefficient The statistical table was used, and the maximum possible retention capacity of the watershed at that time was calculated using the SCS model based on rainfall and surface runoff depth. , and then establish Correlation and regression equations; establish The correlation and regression equations were established; further, the SCS model was used to establish the correlation and regression equations under different antecedent rainfall conditions. Dynamic equations.

[0019] It is worth noting that when historical flood data for the target reservoir is insufficient, data from hydrological stations near the reservoir can be used for analysis.

[0020] In one embodiment, multi-year hydrological and rainfall data from hydrological stations near the reservoir are collected through methods such as consulting relevant materials, and then compiled to form the average total rainfall for each flood event. Surface runoff depth Early impact on rainfall The statistical table, namely the parameter statistical table for each flood event, is in the following format: It should be noted that the calculation methods for the surface runoff coefficient and total runoff coefficient are as follows: Surface runoff coefficient = Surface runoff volume / Average total rainfall; Total runoff coefficient = Total runoff volume / Average total rainfall.

[0021] In addition, the parameter statistics table for each flood event should also include relevant statistical parameters of total runoff depth. However, due to the dense parameter types in the table, the relevant statistical parameters of total runoff depth are not shown in the parameter statistics table of this embodiment.

[0022] Optionally, step S22, based on hydrological and rainfall data, calculates the average total rainfall, antecedent rainfall, total runoff depth, and surface runoff depth for each flood event, including: Extract flood element summary tables and precipitation summary tables corresponding to each rain gauge station in the basin from the water and rainfall data; The rise and fall times of each flood event in the flood element extraction table are used as time constraints. The precipitation data within the time constraints and the precipitation data before the rise of each flood event are extracted by referring to the precipitation extraction table of each rain gauge station. Based on time-constrained precipitation data, temporal integration and spatial averaging are performed to obtain the average total rainfall corresponding to each flood event; at the same time, combined with precipitation data within a preset period before the rise of each flood event, the pre-flood impact rainfall of each flood event is calculated. The time sequence of the flow rate changes in the flood element extraction table is verified. Based on the verification results, the missing time changes are interpolated and supplemented. The interpolated time changes are then connected in chronological order to construct the flood process lines for each event. Based on the morphological characteristics of flow changes in the flood hydrograph, the runoff composition of each flood event is divided, and the total runoff and surface runoff of each flood event are calculated. Combined with the catchment area of ​​the target reservoir, the total runoff depth and surface runoff depth of each flood event are calculated.

[0023] In a further embodiment, flood element summary tables and precipitation summary tables are retrieved and organized from hydrological and rainfall data. The flood element summary table includes at least the flow observation time series, flood initiation time, and receding time for each flood event. The precipitation summary table includes at least the precipitation observation time series and corresponding station identification information for each rain gauge station within the basin. The two types of summary tables undergo time format standardization and missing data verification to ensure that subsequent time-constrained joint queries can be performed under the same time reference. Based on this, the flood initiation time and receding time of each flood event recorded in the flood element summary table are used as time constraints to construct a corresponding time query window. The precipitation observation data of each rain gauge station in the precipitation summary table are then retrieved station by station. The precipitation data located within the time query window is extracted as the flood event precipitation data, and continuous historical precipitation data before the flood initiation time is extracted as candidate data for previous precipitation events. Subsequently, the precipitation data extracted within the time constraints were integrated according to a unified time step. The precipitation from each rain gauge during the flood process was summed to obtain the cumulative precipitation for each flood event. Furthermore, the average total rainfall for each flood event was calculated using either an equal-weighted average or a weighted average based on the control area of ​​each rain gauge. Simultaneously, a preset time period (e.g., 15 days) was used to backtrack from the onset time of each flood event. Precipitation data within the backtracking period was filtered, and an attenuation coefficient k (0 < k < 1) was introduced to perform time-weighted processing on early precipitation, giving higher weight to precipitation closer to the onset time. This allowed for the calculation of the initial impact rainfall reflecting the initial water content of the watershed. In the runoff parameter calculation process, the flow time series recorded in the flood element summary table is first checked for temporal order. If discontinuous time intervals or missing flow data at individual moments are found, the missing data is supplemented using linear or smooth interpolation based on the flow change trends of adjacent moments. The supplemented flow data are then connected in chronological order to construct a continuous and complete flood hydrograph for each event. This process ensures the continuity and integrity of the flood hydrograph in the time dimension. Furthermore, the runoff components are divided based on the morphological characteristics of flow changes over time in the constructed flood hydrograph. Specifically, optionally, the receding section of the flood hydrograph is used as a benchmark, and a decreasing exponential parameter is used to fit the groundwater runoff baseline. The portion of the flood hydrograph above the groundwater runoff baseline is identified as the surface runoff component, and the remaining portion is identified as the groundwater runoff component. By integrating the complete flood hydrograph over time, the total runoff and surface runoff of each flood event are calculated. Then, by combining the area of ​​the corresponding watershed of the target reservoir, the runoff is converted into an equivalent water depth, thereby obtaining the total runoff depth and surface runoff depth of each flood event.

[0024] It is worth noting that the area of ​​the catchment corresponding to the target reservoir can be obtained by checking hydrological stations near the reservoir or by consulting relevant materials.

[0025] In a further embodiment, the average total rainfall... Surface runoff depth Substitute these values ​​into the SCS model equation to calculate the maximum possible stagnation flow. ; according to ,when hour, The maximum possible retention capacity of each flood event was calculated. As shown in the table below: Optionally, the method for obtaining the SCS model relation in step S23 includes: The pre-set SCS formula and the water balance equation are solved simultaneously to obtain the SCS model relationship; The SCS formula is as follows: ; The water balance equation is as follows: ; The specific SCS model relationship obtained by solving the SCS formula and the water balance equation simultaneously is as follows: ; In the formula, This represents the average total rainfall. For surface runoff depth, For initial rainfall loss, This refers to the amount of infiltration. This represents the maximum possible retention capacity of the basin at that time; including the initial rainfall loss. The value is 0.2S.

[0026] Optionally, step S25 includes: Divide the total runoff depth and surface runoff depth in the parameter statistics table for each flood event by the average total rainfall. The results of this division are the runoff coefficients corresponding to the total runoff depth and surface runoff depth, respectively. The formula for calculating the surface runoff coefficient is as follows: ; in, This is the surface runoff coefficient. This represents the average total rainfall. This refers to the depth of surface runoff. The formula for calculating the total runoff coefficient is: ; in, The total runoff coefficient, This represents the average total rainfall. Total runoff depth; A correlation curve between surface runoff coefficient and total runoff coefficient was established based on the total runoff coefficient and surface runoff coefficient.

[0027] In a further embodiment, a surface runoff coefficient is established. With total runoff coefficient The relevant curve, i.e. and establish and The regression equation is as follows: .

[0028] Optionally, step S26 includes: Based on the correlation curve between the previous impact rainfall and the maximum possible retention flow, the maximum possible retention flow corresponding to the previous impact rainfall is obtained; Based on the SCS model relationship, the relationship curve between average total rainfall and surface runoff depth is derived. Based on the correlation curve between surface runoff coefficient and total runoff coefficient, the total runoff coefficient corresponding to the surface runoff coefficient is obtained. Combined with the relationship curve between average total rainfall and surface runoff depth, the equations are substituted into the calculation formula of surface runoff coefficient to solve the problem simultaneously, thus obtaining the relationship curve between average total rainfall and total runoff coefficient, i.e., the dynamic equation of rainfall-runoff coefficient based on underlying surface conditions.

[0029] In a further embodiment, the maximum possible stagnant flow rate is established. Compared with the previous impact on rainfall The relevant curve, i.e. and establish and The regression equation is as follows: ; In a further embodiment, according to The relevant curve can be used to calculate... corresponding The value is then used in the SCS model relation, i.e., when hour, The average total rainfall was derived. and surface runoff depth The relationship curve, i.e. Further utilization It can be found that corresponding Value, then used The formula for calculating the surface runoff coefficient ( = × ) can be obtained and The curve representing the relationship, i.e., the dynamic equation of rainfall versus runoff coefficient based on underlying surface conditions. The dynamic equation for rainfall-runoff coefficient based on underlying surface conditions is as follows: Figure 3 As shown; where Figure 3 The rainfall mentioned above is the average total rainfall. .

[0030] Optionally, step S3 includes: Step S31: Solve the dynamic equation of rainfall-runoff coefficient based on reservoir storage and the dynamic equation of rainfall-runoff coefficient based on underlying surface conditions simultaneously to extract the intersection points in the solution results; the intersection points in the solution are the average total rainfall and total runoff coefficient under the corresponding initial water level conditions and the previous influencing rainfall conditions. Step S32: Based on the correspondence between the initial water level conditions, the previous influencing rainfall conditions, the average total rainfall and the total runoff coefficient in the intersection of the solution results, construct a lookup table for rain-holding capacity and runoff coefficient.

[0031] In this embodiment, the intersection point of the dynamic equation of rainfall-runoff coefficient based on reservoir storage and the dynamic equation of rainfall-runoff coefficient based on underlying surface conditions can be calculated by solving the simultaneous equations. A schematic diagram of the intersection point during the solution process is shown below. Figure 4 As shown; It is worth noting that the rainfall carrying capacity refers to the average total amount of rainfall that the reservoir can hold.

[0032] Furthermore, the initial water level conditions, previous influencing rainfall conditions, average total rainfall, and total runoff coefficient corresponding to all curve intersection points are summarized to form a lookup table of reservoir rainfall carrying capacity and runoff coefficient. This lookup table includes a lookup table of reservoir rainfall carrying capacity under different conditions and a lookup table of reservoir runoff coefficient under different conditions; the lookup table of reservoir rainfall carrying capacity under different conditions is shown in the table below: The table below shows the calculation table for runoff coefficients under different reservoir conditions: Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0033] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily 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 invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient, characterized in that, Includes the following steps: Step S1: Collect data including the target reservoir's catchment area, characteristic water level, and water level-reservoir capacity relationship curve; A dynamic equation for rainfall-runoff coefficient based on reservoir storage was established using the characteristic water level and reservoir capacity relationship curve. Step S2: Collect historical flood data of the target reservoir and analyze the data to generate a parameter statistical table for each flood event; establish a dynamic equation for rainfall-runoff coefficient based on underlying surface conditions according to the parameter statistical table for each flood event. Step S3: Solve the dynamic equations of rainfall-runoff coefficient based on reservoir storage and rainfall-runoff coefficient based on underlying surface conditions simultaneously, and establish a lookup table of rainwater carrying capacity and runoff coefficient based on the intersection points in the solution.

2. The method for calculating reservoir rainfall carrying capacity based on dynamic runoff coefficient according to claim 1, characterized in that, Step S3 is followed by: Obtain the rainfall data of the target reservoir and the initial water level of the target reservoir at the target time, and use the rainfall data of the target reservoir to calculate the antecedent rainfall at the target time; Based on the initial water level of the target reservoir at the target time and the preceding impact rainfall at the target time, a lookup table for the rain-carrying capacity and runoff coefficient is used to obtain the rain-carrying capacity and runoff coefficient of the target reservoir at the target time.

3. The method for calculating reservoir rainwater carrying capacity based on dynamic runoff coefficient according to claim 1, characterized in that, Step S1 includes: Step S11: Collect data including the target reservoir's catchment area, characteristic water levels, and water level-reservoir capacity relationship curves; where the characteristic water levels include the reservoir's flood control limit water level, design water level, and check water level; Step S12: Compare the water level-reservoir capacity relationship curve with the characteristic water level to calculate the reservoir capacity difference between different initial water levels and characteristic water levels; Step S13: Establish a dynamic equation for rainfall-runoff coefficient based on reservoir storage by using the preset reservoir water balance equation and based on characteristic parameters and the difference in reservoir capacity between different initial water levels and characteristic water levels.

4. The method for calculating reservoir rainfall carrying capacity based on dynamic runoff coefficient according to claim 1, characterized in that, The reservoir water balance equation in step S13 is as follows: ； in, The difference in reservoir capacity is the water storage volume corresponding to the characteristic water level and the water storage volume corresponding to the initial water level. This represents the water storage volume corresponding to the characteristic water level. This represents the reservoir's water storage capacity corresponding to the initial water level. The target reservoir's catchment area; Total runoff depth; This represents the average total rainfall. This represents the total runoff coefficient.

5. The method for calculating reservoir rainfall carrying capacity based on dynamic runoff coefficient according to claim 1, characterized in that, Step S2 includes: Step S21: Collect historical flood data for the target reservoir; Step S22: Based on the water and rainfall data, calculate the average total rainfall, the amount of rainfall affecting the preceding flood, the total runoff depth, and the surface runoff depth for each flood event, thereby generating a parameter statistical table for each flood event; Step S23: Substitute the average total rainfall and surface runoff depth corresponding to each flood in the parameter statistics table of each flood into the preset SCS model relationship to calculate the maximum possible retention flow of the watershed at that time for each flood. Step S24: Establish the correspondence between the maximum possible retention capacity and the previous impact rainfall for each flood event, and use the previous impact rainfall as the independent variable and the maximum possible retention capacity as the dependent variable to fit the changing trend between the independent and dependent variables, so as to construct the correlation curve between the previous impact rainfall and the maximum possible retention capacity. Step S25: Establish the correlation curve between surface runoff coefficient and total runoff coefficient based on the parameter statistics table of each flood event; Step S26: Based on the correlation curves of previous impact rainfall ~ maximum possible retention flow and surface runoff coefficient ~ total runoff coefficient, derive the dynamic equation of rainfall ~ runoff coefficient based on underlying surface conditions.

6. The method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient according to claim 5, characterized in that, Step S22 involves calculating the average total rainfall, antecedent rainfall, total runoff depth, and surface runoff depth for each flood event based on hydrological and rainfall data. Extract flood element summary tables and precipitation summary tables corresponding to each rain gauge station in the basin from the water and rainfall data; The rise and fall times of each flood event in the flood element extraction table are used as time constraints. The precipitation data within the time constraints and the precipitation data before the rise of each flood event are extracted by referring to the precipitation extraction table of each rain gauge station. Based on time-constrained precipitation data, temporal integration and spatial averaging are performed to obtain the average total rainfall corresponding to each flood event; at the same time, combined with precipitation data within a preset period before the rise of each flood event, the pre-flood impact rainfall of each flood event is calculated. The time sequence of the flow rate changes in the flood element extraction table is verified. Based on the verification results, the missing time changes are interpolated and supplemented. The interpolated time changes are then connected in chronological order to construct the flood process lines for each event. Based on the morphological characteristics of flow changes in the flood hydrograph, the runoff composition of each flood event is divided, and the total runoff and surface runoff of each flood event are calculated. Combined with the catchment area of ​​the target reservoir, the total runoff depth and surface runoff depth of each flood event are calculated.

7. The method for calculating reservoir rainwater carrying capacity based on dynamic runoff coefficient according to claim 5, characterized in that, The methods for obtaining the SCS model relation in step S23 include: The pre-set SCS formula and the water balance equation are solved simultaneously to obtain the SCS model relationship; The SCS formula is as follows: ； The water balance equation is as follows: ； The specific SCS model relationship obtained by solving the SCS formula and the water balance equation simultaneously is as follows: ； In the formula, This represents the average total rainfall. For surface runoff depth, For initial rainfall loss, This refers to the amount of infiltration. This represents the maximum possible retention capacity of the basin at that time; including the initial rainfall loss. The value is 0.2S.

8. The method for calculating reservoir rainwater carrying capacity based on dynamic runoff coefficient according to claim 5, characterized in that, Step S25 includes: Divide the total runoff depth and surface runoff depth in the parameter statistics table for each flood event by the average total rainfall. The results of this division are the runoff coefficients corresponding to the total runoff depth and surface runoff depth, respectively. The formula for calculating the surface runoff coefficient is as follows: ； in, This is the surface runoff coefficient. This represents the average total rainfall. This refers to the depth of surface runoff. The formula for calculating the total runoff coefficient is: ； in, The total runoff coefficient, This represents the average total rainfall. Total runoff depth; A correlation curve between surface runoff coefficient and total runoff coefficient was established based on the total runoff coefficient and surface runoff coefficient.

9. The method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient according to claim 1, characterized in that, Step S26 includes: Based on the correlation curve between the previous impact rainfall and the maximum possible retention flow, the maximum possible retention flow corresponding to the previous impact rainfall is obtained; Based on the SCS model relationship, the relationship curve between average total rainfall and surface runoff depth is derived. Based on the correlation curve between surface runoff coefficient and total runoff coefficient, the total runoff coefficient corresponding to the surface runoff coefficient is obtained. Combined with the relationship curve between average total rainfall and surface runoff depth, the equations are substituted into the calculation formula of surface runoff coefficient to solve the problem simultaneously, thus obtaining the relationship curve between average total rainfall and total runoff coefficient, i.e., the dynamic equation of rainfall-runoff coefficient based on underlying surface conditions.

10. The method for calculating the rainwater carrying capacity of a reservoir based on a dynamic runoff coefficient according to claim 1, characterized in that, Step S3 includes: Step S31: Solve the dynamic equation of rainfall-runoff coefficient based on reservoir storage and the dynamic equation of rainfall-runoff coefficient based on underlying surface conditions simultaneously to extract the intersection points in the solution results; the intersection points in the solution are the average total rainfall and total runoff coefficient under the corresponding initial water level conditions and the previous influencing rainfall conditions. Step S32: Based on the correspondence between the initial water level conditions, the previous influencing rainfall conditions, the average total rainfall and the total runoff coefficient in the intersection of the solution results, construct a lookup table for rain-holding capacity and runoff coefficient.

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