Basin unit hydrograph simulation method based on forecast period and shape parameters, and application

Abstract

Provided in the present invention are a basin unit hydrograph simulation method based on a forecast period and shape parameters, and an application. An instantaneous unit hydrograph formula based on a forecast period and shape parameters is used to calculate an instantaneous unit hydrograph of a basin. The beneficial effects of the present invention lie in: regardless of the values of parameters Tp and C3, the instantaneous unit hydrograph formula based on a forecast period and shape parameters that is provided in the present invention has the following several features: an area enclosed by the formula and a time axis being equal to 1; the form of a function being increased first and then reduced, and the function being a unimodal function; and within the range of t≥0, values of the function all being greater than or equal to 0. The above properties make the function naturally comply with several basic definitions of unit hydrographs; and many difficulties in conventional derivation of unit hydrographs are avoided, parameters can be quickly determined, the efficiency of calibration and computation of the present unit hydrograph method are improved, and with respect to a Nash instantaneous unit hydrograph, the parameters Tp and C3 have clear physical meanings, thereby facilitating the parameter calibration and application promotion of the provided method.

Description

A watershed unit line simulation method based on forecast period and shape parameters and its application Technical Field

[0001] The present invention belongs to the technical field of numerical calculation of water conservancy projects, and in particular relates to a watershed unit line simulation method based on a forecast period and shape parameters and its application. Background Art

[0002] The flow process at a river basin outlet is a key focus of flood forecasting and a critical input parameter in high-precision river hydrodynamic model calculations. Using a river basin unit line for short-term flood forecasting is a widely used technique. The definition of a river basin unit line can be expressed as: for any specific river basin, the surface runoff process at the river basin outlet station formed by a unit of net rainfall uniformly distributed over a unit period of time is called a unit line. The river basin unit line is a conceptual black box model whose application adheres to the principle of multiple superposition.

[0003] However, deriving the unit line of a watershed in the traditional sense is difficult. Many constraints are often imposed on the definition of the unit line (for example, the unit line first increases and then decreases, the area enclosed by the unit line and the time axis is equal to the watershed precipitation, and all values ​​on the unit line are greater than or equal to zero). The solution is then sought using optimization algorithms such as analysis, trial and error, least squares, and linear programming. Even so, some derived unit lines still exhibit a jagged shape, inconsistent with general natural laws. Another approach is to apply the Nash instantaneous unit line formula. However, the Nash instantaneous unit line essentially equates the watershed to a series of n linear reservoirs with the same storage and regulation function. This mathematically successful approach is however quite far-fetched in terms of physics, resulting in the Nash instantaneous unit line parameters (i.e., n and K) lacking an intuitive physical interpretation.

[0004] Summary of the Invention

[0005] In view of this, the present invention aims to propose a basin unit line simulation method and application based on forecast period and shape parameters. The basin unit line model is simple and practical, and the model parameters have clear physical meanings, thereby overcoming the difficulties in deriving traditional basin unit lines and the unclear physical meanings of Nash instantaneous unit line parameters, and providing a solution for basin flood forecasting.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A method for simulating a watershed unit line based on a forecast period and shape parameters includes an instantaneous unit line formula based on the forecast period and shape parameters. The instantaneous unit line of the watershed is calculated using the instantaneous unit line formula based on the forecast period and shape parameters. The instantaneous unit line formula based on the forecast period and shape parameters is:

[0008] Where Q(t) is the instantaneous unit line of the basin; Q is the calculated surface runoff; T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; exp() represents the exponential function; Gamma() represents the gamma function.

[0009] Further, the following steps are included:

[0010] S1: Collect basin hydrological data;

[0011] S2: Apply the instantaneous unit line formula based on the forecast period and shape parameters;

[0012] S3: Convert the instantaneous unit line based on the forecast period and shape parameters into the period unit line;

[0013] S4: Parameter T of the unit line of the time period is determined based on the historical data of the basin p , C3;

[0014] S5: Use the derived time period unit line for short-term flood forecasting.

[0015] Furthermore, in step S1, the watershed hydrological data required for unit line flood forecasting are collected, wherein the watershed hydrological data include the watershed area F, the time series of historical floods, the net rainfall series, and the measured surface runoff series.

[0016] Furthermore, in step S3, the instantaneous unit line based on the forecast period and the shape parameter is converted into a time period unit line, including the following steps:

[0017] S31. Calculate the integral of the instantaneous unit line with respect to time t:

[0018] Where S(t) is the time integral function of the instantaneous unit line of the watershed; Q(τ) is the instantaneous unit line of the watershed; τ is the time variable of the integration;

[0019] get:

[0020] Where S(t) is the time integral function of the instantaneous unit line of the watershed; C3 is the shape parameter; T p is the forecast period; the two-parameter Gamma function is the upper incomplete gamma function;

[0021] S32. By subtracting the two S curves, we can get the time period unit line:

[0022] U(Δt, t) = S(t) - S(t - Δt);

[0023] Where U(Δt, t) is the time period unit line; Δt is the time interval; S(t) is the integral function of the instantaneous unit line of the basin with respect to time; S(t, Δt) is the S-curve with a delay of Δt on the time axis;

[0024] get:

[0025] Where U(Δt, t) is the time period unit line; Gamma() represents the gamma function; T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; Δt is the time interval; max() is the maximum value function;

[0026] S33. In particular, for a watershed area of ​​F, the unit is km 2 , the time interval is Δt, the unit is h, and the net rain is 10mm unit line:

[0027] Where q(Δt, t) is the unit line corresponding to 10 mm of net rainfall; F is the basin area; Δt is the time interval; and U(Δt, t) is the unit line of the time period.

[0028] Furthermore, in step S4, the parameter T of the unit line of the time period is calibrated according to the historical data of the watershed. p , C3, including the following calibration process:

[0029] Divide the net rainfall in each period by 10 mm and multiply it by the period unit line of 10 mm net rainfall to obtain the outflow process corresponding to the net rainfall in this period;

[0030] The outflow processes generated by the net rainfall in each period are arranged in order on the time axis, and the outflow processes are superimposed on the time axis to obtain the flood simulation results; the formula is:

[0031] Among them, Q c，i is the historical flood simulation result of the i-th period; r j is the net rainfall in the jth period; i is the simulation period number; j is the period number of the unit line calculation, and 1≤j≤i; q(Δt, t) is the unit line corresponding to 10 mm net rainfall; Δt is the time interval.

[0032] Furthermore, in step S4, the parameter calibration adopts the principle of minimum error of historical flood simulation to determine the parameter T of the unit line. p and C3, the parameter calibration process uses a parameter calibration algorithm, which is the ergodic method, the trial and error method, or the SCE-UA method.

[0033] Furthermore, in step S5, the derived time period unit line is used to perform short-term flood forecasting, including the following contents:

[0034] When using the derived time unit line for short-term flood forecasting, the net rainfall in each time period is divided by 10 mm, and then multiplied by the time unit line of 10 mm net rainfall to obtain the outflow process corresponding to the net rainfall in this time period;

[0035] The outflow processes generated by the net rainfall in each period are sorted in order on the time axis, and the outflow processes are superimposed on the time axis to obtain the flood forecast results; the formula is:

[0036] Among them, Q c，i is the flood forecast result of the i-th time period; r j is the net rainfall in the jth period; i is the forecast period number; j is the period number for unit line calculation, and 1≤j≤i; q(Δt, t) is the unit line corresponding to 10 mm net rainfall; Δt is the time interval.

[0037] Furthermore, an electronic device includes a processor and a memory connected to the processor for storing instructions executable by the processor, wherein the processor is used to execute the above-mentioned method for short-term flood forecasting.

[0038] Furthermore, a server includes at least one processor and a memory communicatively connected to the processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor to enable the at least one processor to perform the above-mentioned short-term flood forecasting method.

[0039] Furthermore, a computer-readable storage medium stores a computer program, which implements the above-mentioned short-term flood forecasting method when executed by a processor.

[0040] Compared with the existing technology, the basin unit line simulation method based on the forecast period and shape parameters and its application described in the present invention have the following advantages:

[0041] (1) The method and application of simulating a watershed unit line based on the forecast period and shape parameters proposed in the present invention. The instantaneous unit line formula based on the forecast period and shape parameters proposed in the present invention is irrespective of the parameter T p Regardless of the value of C3, the function possesses the following characteristics: the area enclosed by the time axis is equal to 1; the function shape first increases and then decreases, forming a unimodal function; and within the range t ≥ 0, the function value is always greater than or equal to 0. These properties naturally allow the function to meet several basic definitions of the unit curve, avoiding the many difficulties of traditional derivation of the unit curve, allowing for rapid parameter calibration, and improving the calibration and computational efficiency of this unit curve method.

[0042] (2) The method and application of the watershed unit line simulation method based on the forecast period and shape parameters described in the present invention, the function peak of the method appears at t = T p At, that is: T p Intuitively represents the basin forecast period. In practical applications, very little hydrological data can be used to determine the parameter T p approximate range.

[0043] (3) The basin unit line simulation method and application based on the forecast period and shape parameters described in the present invention is compared with the Nash instantaneous unit line. The function peak occurrence time is determined only by the parameter T. p Decision, in T p After the function is determined, the shape is determined by the parameter C3. The physical meaning is clear, which facilitates the parameter calibration and application promotion of the proposed method. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0045] FIG1 is a diagram showing a function graph of an instantaneous unit line formula based on a look-ahead period and shape parameters according to an embodiment of the present invention;

[0046] FIG2 shows an embodiment of the present invention wherein the instantaneous unit line parameter T is determined when the parameter C3 is determined. p Schematic diagram of the relationship with the function result;

[0047] FIG. 3 shows the parameter T in an embodiment of the present invention. p Determine the relationship between the proposed instantaneous unit line parameter C3 and the function result;

[0048] FIG4 is a schematic diagram of a curve showing a time period unit line obtained by subtracting two S-curves according to an embodiment of the present invention;

[0049] FIG5 is a schematic diagram of contour lines of the evaluation index NSE during the parameter calibration process according to an embodiment of the present invention;

[0050] FIG6 is a schematic diagram of the optimal result after parameter calibration according to an embodiment of the present invention;

[0051] FIG7 is a schematic diagram of a time period unit line obtained by calibration according to an embodiment of the present invention;

[0052] FIG8 is a schematic diagram of short-term flood forecasting using the derived time period unit line according to an embodiment of the present invention;

[0053] FIG9 is a schematic flow chart of a short-term flood forecasting method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0056] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0057] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0058] As shown in Figures 1 to 9, a method for simulating a watershed unit line based on a forecast period and shape parameters includes an instantaneous unit line formula based on a forecast period and shape parameters. The instantaneous unit line of the watershed is calculated using the instantaneous unit line formula based on a forecast period and shape parameters. The instantaneous unit line formula based on a forecast period and shape parameters is:

[0059] Where Q(t) is the instantaneous unit line of the basin; Q is the calculated surface runoff; T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; exp() represents the exponential function; Gamma() represents the gamma function.

[0060] As shown in FIG9 , in a preferred embodiment of the present invention, a method for short-term flood forecasting is proposed, which applies the above-mentioned watershed unit line simulation method based on the forecast period and shape parameters, and includes the following steps: S1: collecting watershed hydrological data;

[0061] Collect the watershed hydrological data required for unit line flood forecasting, which include watershed area F, time series of historical floods, net rainfall series, and measured surface runoff series.

[0062] S2: Apply the instantaneous unit line formula based on the forecast period and shape parameters;

[0063] Assume that the instantaneous unit line of the basin can be expressed as:

[0064] Where Q is the calculated surface runoff, T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; exp() represents the exponential function; Gamma() represents the gamma function.

[0065] S3: Convert the instantaneous unit line based on the forecast period and shape parameters into the period unit line;

[0066] Compute the integral of the instantaneous unit line with respect to time t:

[0067] Where S(t) is the integral function of the instantaneous unit line of the watershed with respect to time (also called S curve); Q(τ) is the instantaneous unit line of the watershed; τ is the time variable of the integration;

[0068] get:

[0069] Where S(t) is the time integral function of the instantaneous unit line of the watershed (also called S curve); C3 is the shape parameter; T p is the forecast period; the two-parameter Gamma function is the upper incomplete gamma function.

[0070] By subtracting the two S curves, we can get the time period unit line:

[0071] U(Δt,t)=S(t)-S(t-Δt);

[0072] Where U(Δt, t) is the time period unit line; Δt is the time interval; S(t) is the integral function of the instantaneous unit line of the basin with respect to time (also called S curve); S(t, Δt) is the S curve with a delay of Δt on the time axis;

[0073] get:

[0074] Where U(Δt, t) is the time period unit line; Gamma() represents the gamma function; T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; Δt is the time interval; max() is the maximum value function.

[0075] In particular, for a watershed area of ​​F (km 2 ), time interval Δt (h), net rainfall of 10 (mm) unit line:

[0076] Where q(Δt, t) is the unit line corresponding to 10 mm of net rainfall; F is the basin area; Δt is the time interval; and U(Δt, t) is the unit line of the time period.

[0077] S4: Parameters of unit line of time period (T p , C3);

[0078] According to the actual needs of basin flood forecasting, the unit time length Δt of the unit line is determined, and the given parameter T p , C3, the time unit line proposed in this invention can be used to simulate historical floods. The specific process is: divide the net rainfall in each time period by 10mm, then multiply it by the time unit line of 10mm net rainfall to obtain the outflow process corresponding to the net rainfall in this time period. The outflow processes generated by each net rainfall are sorted in order on the time axis, and the outflow processes are superimposed on the time axis to obtain the flood forecast result. The formula is:

[0079] Among them, Q c，i is the historical flood simulation result of the i-th period; r j is the net rainfall in the jth period (unit: mm); i is the period number of the simulation; j is the period number of the unit line calculation (1≤j≤i); q(Δt, t) is the unit line corresponding to 10 mm net rainfall; Δt is the time interval.

[0080] The parameter calibration of this method adopts the principle of minimum error of historical flood simulation to determine the parameter T of the unit line. p For C3 and C4 parameters, any mature parameter calibration algorithm can be used. Recommended algorithms include the traversal method, trial and error method, and SCE-UA method.

[0081] S5: Use the derived time period unit line to make short-term flood forecasts;

[0082] After determining the unit time length Δt of the unit line in the time period, the optimal parameter T is obtained by calibration. pAfter obtaining C3, the derived time unit line can be used for short-term flood forecasting. During the forecast calculation, the net rainfall in each time period is divided by 10mm, and then multiplied by the time unit line of 10mm net rainfall to obtain the outflow process corresponding to the net rainfall in this time period. The outflow processes generated by the net rainfall in each time period are sorted in order on the time axis, and the outflow processes are superimposed on the time axis to obtain the flood forecast result; the formula is:

[0083] Among them, Q c，i is the flood forecast result of the i-th time period; r j is the net rainfall in the jth period (unit: mm); i is the forecast period number; j is the period number for unit line calculation (1≤j≤i); q(Δt, t) is the unit line corresponding to 10 mm net rainfall; Δt is the time interval.

[0084] Formula derivation process:

[0085] The S3 derivation process is as follows:

[0086] When converting the instantaneous unit line to the time period unit line, the S curve is used. According to the definition of the S curve:

[0087] Get the expression of the S curve:

[0088] The integrated expression is:

[0089] The two-parameter Gamma function is the upper incomplete gamma function.

[0090] By subtracting the two S curves, we can get the time period unit line:

[0091] U(Δt,t)=S(t)-S(t-Δt);

[0092] get:

[0093] Where max() is the maximum value function.

[0094] For a watershed area of ​​F(km 2 ), time interval Δt (h), net rainfall of 10 (mm) unit line:

[0095] About the incomplete Gamma function:

[0096] In Mathematica, Gamma() represents the upper incomplete Gamma function, while in Matlab, gammainc(z, a) represents the normalized lower incomplete Gamma function. The incomplete Gamma function in the present specification is consistent with that in the mathematical software Mathematica. Readers who attempt this method in the mathematical software Matlab should pay attention to this difference.

[0097] Advantages of the present invention:

[0098] (1) The instantaneous unit line formula based on the forecast period and shape parameters proposed in this invention is irrespective of the parameter T p Regardless of the value of C3, the function possesses the following characteristics: the area enclosed by the time axis is equal to 1; the function shape first increases and then decreases, forming a unimodal function; and within the range t ≥ 0, the function value is always greater than or equal to 0. These properties naturally allow the function to meet several basic definitions of the unit curve. This avoids the many difficulties of traditional derivation of the unit curve, allows for rapid parameter calibration, and improves the calibration and computational efficiency of this unit curve method.

[0099] (2) The function peak occurs at t = T p At, that is: T p Intuitively represents the basin forecast period. In practical applications, very little hydrological data can be used to determine the parameter T p approximate range.

[0100] (3) Compared with the Nash instantaneous unit line, the time when the function peak appears is determined only by the parameter T p Decision, in T p After the function is determined, the shape is determined by the parameter C3. The physical meaning is clear, which facilitates the parameter calibration and application promotion of the proposed method.

[0101] Example 1

[0102] 1) Collect basin hydrological data;

[0103] Taking the calculation example on page 71 of Hydrological Forecast (4th edition) published by China Water Resources and Hydropower Press as an example, we collected historical flood data of the basin controlled by Kaifenggu Station of Nanhe River, including basin area, time, net rainfall during each period, and measured surface runoff. The basin area is 5239.02km 2 , other information is shown in the following table.

[0104] 2) Apply the instantaneous unit line formula based on the forecast period and shape parameters;

[0105] The process of the embodiment is exactly the same as that described in S2 and will not be repeated here.

[0106] To intuitively demonstrate the formula proposed in the present invention, FIG1 shows a function graph of the instantaneous unit line formula based on the forecast period and shape parameters; FIG2 shows the instantaneous unit line parameter T when the parameter C3 is determined. p The relationship with the function result; Figure 3 shows that when the parameter T p Determine the relationship between the proposed instantaneous unit line parameter C3 and the function result.

[0107] 3) Convert the instantaneous unit line based on the forecast period and shape parameters into a time period unit line;

[0108] The process of the embodiment is exactly the same as that described in S3 and will not be repeated here.

[0109] In order to intuitively demonstrate the method proposed in the present invention, FIG4 shows a curve diagram of a time period unit line obtained by subtracting two S curves.

[0110] 4) Parameters of the time period unit line are determined based on historical data of the watershed;

[0111] In this embodiment, based on the collected data, the unit time period Δt=6h of the unit line flood forecast is determined. The parameter T of the unit line is calculated using the ergodic method. p and C3 to optimize the parameters, and use the Nash efficiency coefficient (NSE) to evaluate the quality of the simulation process, that is, for a given T p , C3 parameter optimization interval, optimization step, traverse all possible parameter combinations, calculate the NSE value of the simulation results under each set of parameter combination conditions (NSE≤1), and the NSE value close to 1 indicates that the closer the simulation result is to the observation, the parameter combination with the largest NSE is taken as the optimal parameter.

[0112] In this embodiment, the parameter T p The optimal search interval is 1h≤T p ≤24h, the optimization step length is 1h; the optimization interval of parameter C3 is 0.1≤C3≤5, and the optimization step length is 0.2. All parameter combinations in the above interval are traversed and calculated, and the obtained NSE contour map is shown in Figure 5. The maximum NSE = 0.94 is the optimal parameter: T p =9, C3=1.1, the optimal parameters, the historical data simulation results are shown in Figure 6.

[0113] 5) Use the derived time period unit line to conduct short-term flood forecasting;

[0114] The utilization rate is determined to obtain the optimal parameters and determine the unit line of the time period. In this embodiment, the basin area F = 5239.02 km 2 , the time interval is Δt = 6h, and the generally accepted unit line of net rain of 10mm is adopted, and the unit line is obtained as shown in Figure 7.

[0115] Assume that there is a rainfall in the basin in the future, and the net rainfall in the period is shown in the following table.

[0116] The results of short-term flood forecasting using the time period unit line are shown in Figure 8.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for simulating unit lines in a watershed based on forecast period and shape parameters, characterized in that: Including the instantaneous unit line formula based on the forecast period and shape parameters, the instantaneous unit line of the basin is calculated by using the instantaneous unit line formula based on the forecast period and shape parameters. The instantaneous unit line formula based on the forecast period and shape parameters is: Where Q(t) is the instantaneous unit line of the basin; Q is the calculated surface runoff; T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; exp() represents the exponential function; Gamma() represents the gamma function.

2. A method for short-term flood forecasting, using the basin unit line simulation method based on forecast period and shape parameters as claimed in claim 1, characterized in that: The following steps are involved: S1: Collect basin hydrological data; S2: Apply the instantaneous unit line formula based on the forecast period and shape parameters; S3: Convert the instantaneous unit line based on the forecast period and shape parameters into the time period unit line; S4: Parameter T of the unit line for a certain period of time based on the historical data of the basin p , C3; S5: Use the derived time period unit line for short-term flood forecasting.

3. A method for short-term flood forecasting according to claim 2, characterized in that: In step S1, the watershed hydrological data required for unit line flood forecasting are collected, wherein the watershed hydrological data include the watershed area F, the time series of historical floods, the net rainfall series, and the measured surface runoff series.

4. A method for short-term flood forecasting according to claim 3, characterized in that: In step S3, the instantaneous unit line based on the forecast period and the shape parameter is converted into a time period unit line, including the following steps: S31. Calculate the integral of the instantaneous unit line with respect to time t: Among them, S(t) is the integral function of the instantaneous unit line of the basin with respect to time; Q(τ) is the instantaneous unit line of the basin; τ is the time variable of integration; get: Where S(t) is the integral function of the instantaneous unit line of the basin with respect to time; C3 is the shape parameter; T p is the forecast period; the two-parameter Gamma function is the upper incomplete Gamma function; S32. By subtracting two S curves, we can get the time period unit line: U(Δt, t) = S(t) - S(t - Δt); Among them, U(Δt, t) is the time unit line; Δt is the time interval; S(t) is the integral function of the instantaneous unit line of the basin with respect to time; S(t, Δt) is the S curve with a delay of Δt on the time axis; get: Where U(Δt, t) is the unit line of the time period; Gamma() represents the gamma function; T p , C3 is the instantaneous unit line parameter, where T p is the forecast period, C3 is the shape parameter; Δt is the time interval; max() is the maximum value function; S33. In particular, for a watershed area of ​​F, the unit is km 2 , time interval Δt, unit h, unit line with net rain of 10 mm: Where q(Δt, t) is the unit line corresponding to 10 mm of net rainfall; F is the basin area; Δt is the time interval; and U(Δt, t) is the unit line of the time period.

5. A short-term flood forecasting method according to claim 4, characterized in that: In step S4, the parameter T of the unit line of the time period is calibrated according to the historical data of the watershed. p , C3, including the following calibration process: divide the net rainfall in each period by 10 mm, and then multiply it by the unit line of the period with a net rainfall of 10 mm to obtain the outflow process corresponding to the net rainfall in this period; The outflow processes generated by the net rainfall in each period are arranged in order on the time axis, and each outflow process is superimposed on the time axis to obtain the flood simulation result; the formula is: Among them, Q c，i is the historical flood simulation result of the i-th period; r j is the net rainfall in the jth period; i is the simulated period number; j is the period number for unit line calculation, and 1≤j≤i; q(Δt, t) is the unit line corresponding to 10 mm net rainfall; Δt is the time interval.

6. A method for short-term flood forecasting according to claim 5, characterized in that: In step S4, the parameter calibration adopts the principle of minimum error of historical flood simulation to determine the parameter T of the unit line. p and C3, the parameter calibration process uses a parameter calibration algorithm, and the parameter calibration algorithm is the ergodic method or the trial and error method or the SCE-UA method.

7. A short-term flood forecasting method according to claim 5, characterized in that: In step S5, the derived time period unit line is used to perform short-term flood forecasting, including the following contents: When using the derived time unit line for short-term flood forecasting, divide the net rainfall in each time period by 10 mm, and then multiply it by the time unit line of 10 mm net rainfall to obtain the outflow process corresponding to the net rainfall in this time period; The outflow processes generated by the net rainfall in each period are arranged in order on the time axis, and each outflow process is superimposed on the time axis to obtain the flood forecast result; the formula is: Among them, Q c，i is the flood forecast result of the i-th time period; r j is the net rainfall in the jth period; i is the forecast period number; j is the period number for unit line calculation, and 1≤j≤i; q(Δt, t) is the unit line corresponding to 10 mm net rainfall; Δt is the time interval.

8. An electronic device, comprising a processor and a memory connected to the processor for storing instructions executable by the processor, characterized in that: The processor is used to execute the short-term flood forecasting method described in any one of claims 2-7.

9. A server, characterized in that: It comprises at least one processor and a memory in communication connection with the processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor so that the at least one processor executes the method for short-term flood forecasting as described in any one of claims 2-7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for short-term flood forecasting described in any one of claims 2-7 is implemented.

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