A flash flood forecasting method and system based on mountain pond flood control coupling

Abstract

The present invention discloses a flash flood forecasting method and system based on mountain pond flood regulation coupling, which belongs to the technical field of flood forecasting in small watersheds in mountainous areas. Existing watershed flood forecasting methods do not take into account the regulating effect of mountain ponds on runoff, resulting in large errors in flash flood forecasting results. The flash flood forecasting method based on mountain pond flood regulation coupling of the present invention processes the basic information of the mountain pond to obtain the initial water level data of the mountain pond; and couples the rainfall data, evaporation data and the initial water level data to obtain the outflow of the mountain pond; and then evolves the outflow flow of the mountain pond to the downstream forecast section to obtain the forecast flood process of the downstream area. Therefore, the present invention can fully consider the impact of mountain ponds on flash floods, thereby effectively improving the accuracy of flash flood disaster forecasting. Furthermore, the application of the present invention can achieve accurate flash flood forecasting, so that relevant departments can issue early warning information in advance, remind the public to evacuate in time, and improve the speed and efficiency of emergency response.

Description

Technical Field

[0001] The invention relates to a mountain flood forecasting method and system based on mountain pond flood regulation coupling, belonging to the technical field of flood forecasting in small watersheds in mountainous areas. Background Art

[0002] Floods are one of the most frequent natural disasters worldwide, especially in mountainous areas. Due to the high, steep slopes and dense streams and rivers, short bursts of heavy rainfall can produce powerful surface runoff within tens to several hours. This high velocity of runoff can be highly destructive, often causing even more severe damage. Therefore, accurate flash flood forecasting is crucial.

[0003] To meet irrigation and drinking water needs, mountain villagers build mountain ponds. These ponds are typically located upstream of river basins, with a storage capacity of 10,000 to 100,000 cubic meters and a depth of 3 to 8 meters. They are primarily used for agricultural irrigation and flood control. The catchment area of ​​a mountain pond typically ranges from 0.5 to 5 square kilometers.

[0004] For large river basins with flat terrain, the drainage area can reach thousands of square kilometers, and the proportion of the rainwater collection area of ​​mountain ponds to the drainage area is very small. Therefore, the impact of mountain ponds on the runoff of large river basins is very small.

[0005] However, for small watersheds in mountainous areas, which typically range in size from 10 to 50 square kilometers, mountain ponds account for a significant portion of the catchment area, significantly altering runoff within the basin. Experience shows that a single mountain pond can reduce peak flood flow by approximately 20%-40%, and if multiple mountain ponds are present, the effect can be compounded. Therefore, if flash flood disaster prediction plans fail to consider the regulating role of mountain ponds, the results will deviate significantly from actual conditions, making it impossible to accurately predict flash floods and hampering the speed and efficiency of emergency response.

[0006] The information disclosed in this Background Art is only for understanding the background of the present inventive concept and therefore it may include information that does not constitute prior art. Summary of the Invention

[0007] In response to the above problem or one of the above problems, the first purpose of the present invention is to provide a mountain torrent forecasting method and system based on mountain pond flood control coupling, processing the basic information of the mountain pond to obtain the initial water level data of the mountain pond; and coupling the rainfall data, evaporation data and initial water level data to obtain the mountain pond outflow; and then evolving the mountain pond outflow to the downstream forecast section to obtain the forecast flood process of the downstream area. Therefore, the present invention can fully consider the impact of mountain ponds on mountain torrents, thereby effectively improving the accuracy of mountain torrent disaster forecasting and improving the level of flood control decision-making support.

[0008] In response to the above problem or one of the above problems, the second purpose of the present invention is to provide a flash flood forecasting method and system based on mountain pond flood control coupling, which can achieve accurate flash flood forecasting, so that relevant departments can issue early warning information in advance to remind the public to evacuate in time; and can provide data support for the formulation and drills of emergency plans, thereby improving the speed and efficiency of emergency response.

[0009] To achieve one of the above purposes, the first technical solution of the present invention is:

[0010] A flash flood forecasting method based on mountain pond flood control coupling includes the following steps:

[0011] Step 1: Obtain basic information of mountain ponds in the area to be predicted;

[0012] Step 2: Process the basic information of the mountain pond to obtain the initial water level data of the mountain pond;

[0013] Step 3: Couple the rainfall data, evaporation data, and initial water level data of the mountain pond to obtain the outflow of the mountain pond;

[0014] Step 4: Evolve the outflow of the mountain pond to the downstream forecast section to obtain the predicted flood process in the downstream area, and realize the mountain flood forecast based on the coupling of mountain pond flood control.

[0015] After continuous exploration and experimentation, the present invention processes the basic information of mountain ponds to obtain the initial water level data of the mountain ponds; and couples the rainfall data, evaporation data and initial water level data to obtain the outflow of the mountain ponds; and then evolves the outflow of the mountain ponds to the downstream forecast section to obtain the forecast flood process of the downstream area. Therefore, the present invention can fully consider the impact of mountain ponds on mountain torrents, thereby effectively improving the accuracy of mountain torrent disaster forecasts and improving the level of support for flood control decision-making.

[0016] Furthermore, the present invention can achieve accurate flash flood forecasts, allowing relevant departments to issue early warning information, reminding people to evacuate in time and minimize casualties. Based on the predicted flood magnitude and arrival time, relevant departments can take appropriate measures to reduce property losses such as infrastructure, farmland, and houses.

[0017] Furthermore, the present invention can also provide data support for the formulation and rehearsal of emergency plans, thereby improving the speed and efficiency of emergency response, and is therefore of great significance.

[0018] As preferred technical measures:

[0019] Step 1: The method for obtaining basic information of mountain ponds in the area to be predicted is as follows:

[0020] The flood discharge method of the mountain pond is free open discharge;

[0021] Based on the free discharge method, obtain the size of the mountain pond, the water level mountain pond storage capacity curve and the mountain pond flood discharge structure;

[0022] Based on the location of the mountain pond, determine the basic information of the watershed, including the watershed area, hydrological characteristics and geological conditions;

[0023] The basic information of mountain ponds in the area to be predicted is obtained by summarizing the scale of mountain ponds, water level mountain pond storage capacity curves, mountain pond flood discharge structures and basic information of the watershed.

[0024] As preferred technical measures:

[0025] Based on the location of the mountain pond, the method for determining the basic information of the watershed is as follows:

[0026] According to the location of the mountain pond, obtain the digital elevation data of the watershed where the mountain pond is located;

[0027] Perform depression filling processing on digital elevation data to obtain watershed raster information;

[0028] Extract water flow direction and river channel information based on watershed raster information;

[0029] Based on the flow direction and river information of the water area, the topological relationship between the mountain pond, river channel and village is analyzed to obtain the mountain pond reservoir area basin and the interval basin;

[0030] The basin area, hydrological characteristics and geological conditions are extracted from the mountain pond reservoir area and the inter-area basin to obtain the basic basin information; the hydrological characteristics include the river length and river slope information.

[0031] As preferred technical measures:

[0032] Step 2: Process the basic information of the mountain pond to obtain the initial water level data of the mountain pond as follows:

[0033] Obtain basic information about mountain ponds;

[0034] Based on the basic information of the mountain pond, analyze the size, design parameters and historical operation data of the mountain pond to determine the initial outflow flow and initial water level data of the mountain pond under different working conditions;

[0035] Combined with real-time monitoring data and mountain pond dispatching rules, the estimated value of the mountain pond's initial water level data is dynamically adjusted.

[0036] As preferred technical measures:

[0037] Step 3: Couple the rainfall data, evaporation data, and initial pond water level data to obtain the pond outflow flow as follows:

[0038] Obtaining rainfall data based on measured rainfall information or forecast rainfall information;

[0039] Calculate the flood process of mountain ponds based on rainfall and evaporation data;

[0040] Based on the initial water level data of the mountain pond and the size of the mountain pond flood discharge structure, the discharge capacity of the mountain pond is calculated, and the discharge capacity relationship curve is obtained to represent the discharge capacity corresponding to different reservoir capacities of the mountain pond;

[0041] Carry out flood control calculation according to the discharge capacity relationship curve and time step to obtain the flood control auxiliary line;

[0042] The flood control auxiliary line is fitted using a polynomial interpolation function to obtain the mountain pond fitting function;

[0043] The outflow flow of the mountain pond at the beginning of the period is taken as the initial flow of the period, and it is substituted into the mountain pond fitting function. The end flow of each period is iteratively calculated, and finally the outflow flow of the mountain pond and the complete outflow flow process of the mountain pond are obtained.

[0044] As preferred technical measures:

[0045] Based on the initial water level data of the mountain pond and the size of the mountain pond flood discharge structure, the method for calculating the mountain pond discharge capacity and obtaining the discharge capacity relationship curve is as follows:

[0046] Based on the initial water level data of the mountain pond and the size of the flood discharge structure of the mountain pond, the digital elevation data of the mountain pond is generated, and the digital elevation data of the mountain pond is horizontally sliced ​​to obtain a number of water level slices;

[0047] Based on several water level slices, calculate the trapezoidal volume between adjacent water levels;

[0048] The reservoir capacity corresponding to different water levels is obtained by adding up the trapezoidal volumes. Combined with the discharge capacity of the mountain pond corresponding to different water levels, the discharge capacity corresponding to different mountain pond storage capacities is obtained, thereby obtaining the discharge capacity relationship curve.

[0049] As preferred technical measures:

[0050] The method for obtaining the flood control auxiliary line by performing flood control calculation based on the discharge capacity relationship curve and time step is as follows:

[0051] Determine the time step and construct the independent and dependent variables based on the discharge capacity relationship curve;

[0052] The independent variable is the discharge capacity, and the dependent variable is the coupling of the mountain pond capacity, the discharge capacity and the time step.

[0053] Based on the independent and dependent variables, a set of discrete data points is established;

[0054] Connect the discrete data points to obtain the flood control auxiliary line;

[0055] Alternatively, or alternatively, use a polynomial interpolation function to fit the flood control auxiliary line. The method for obtaining the fitting function is as follows:

[0056] Use polynomial interpolation function to fit the flood control auxiliary line and obtain the linear equation system:

[0057] Write the linear equations into matrix form to obtain the Shantang fitting matrix, which includes the design matrix, coefficient vector and observation value vector;

[0058] Use the least squares method to solve the coefficient vector and obtain the coefficient expression;

[0059] Based on the coefficient expression, gradually increase the polynomial degree from a low degree, and use the residual sum of squares to evaluate the fitting effect of the Shantang fitting matrix to determine the optimal polynomial degree;

[0060] According to the optimal degree of the polynomial, the final Shantang fitting function is determined.

[0061] As preferred technical measures:

[0062] The method of taking the outflow of the mountain pond at the beginning of the period as the outflow at the beginning of the period and substituting it into the mountain pond fitting function to iteratively calculate the outflow at the end of each period, and finally obtaining the outflow of the mountain pond and the complete outflow process of the mountain pond is as follows:

[0063] Step 1: From the flood process of the mountain pond, obtain the mountain pond inflow flow at the beginning of the period and the mountain pond inflow flow at the end of the period;

[0064] Step 2: Obtain the outflow flow of the mountain pond at the beginning of the period as the initial flow of the period, and substitute the initial flow of the period into the mountain pond fitting function to obtain the intermediate variable;

[0065] Step 3: Substitute the intermediate variables and the inflow into the mountain pond at the beginning and end of the period into the water balance equation to obtain new intermediate variables.

[0066] Step 4: Substitute the new intermediate variable into the mountain pond fitting function to obtain the mountain pond outflow at the end of the period;

[0067] Step 5: Use the mountain pond outflow at the end of the time period calculated in the above steps as the mountain pond outflow at the beginning of the next time period, repeat steps 2 to 4 for iterative calculation, complete the mountain pond flood control calculation for the entire calculation cycle, and obtain the mountain pond outflow and the entire mountain pond outflow process.

[0068] As preferred technical measures:

[0069] Step 4: Evolving the outflow from the mountain pond to the downstream forecast section to obtain the forecast flood process in the downstream area is as follows:

[0070] Obtaining rainfall data based on measured rainfall information or forecast rainfall information;

[0071] Calculate flood processes in interval basins based on rainfall data, mountain pond outflow and evaporation data;

[0072] Determine the interval flood flow of the downstream forecast section according to the interval basin flood process;

[0073] Calculate the average flow velocity of the river using the hydrodynamic parameter calculation method;

[0074] Divide the river channel length by the average river flow velocity to obtain the evolution time of the mountain pond outflow;

[0075] The evolution time of the mountain pond outflow is superimposed on the interval flood flow to obtain the predicted flood process in the downstream area.

[0076] To achieve one of the above purposes, the second technical solution of the present invention is:

[0077] A flash flood forecasting system based on mountain pond flood control coupling, comprising:

[0078] one or more processors;

[0079] a storage device for storing one or more programs;

[0080] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned mountain flood forecasting method based on mountain pond flood regulation coupling.

[0081] Compared with the existing technical solutions, the present invention has the following beneficial effects:

[0082] After continuous exploration and experimentation, the present invention processes the basic information of mountain ponds to obtain the initial water level data of the mountain ponds; and couples the rainfall data, evaporation data and initial water level data to obtain the outflow of the mountain ponds; and then evolves the outflow of the mountain ponds to the downstream forecast section to obtain the forecast flood process of the downstream area. Therefore, the present invention can fully consider the impact of mountain ponds on mountain torrents, thereby effectively improving the accuracy of mountain torrent disaster forecasts and improving the level of support for flood control decision-making.

[0083] Furthermore, the present invention can achieve accurate flash flood forecasts, allowing relevant departments to issue early warning information, reminding people to evacuate in time and minimize casualties. Based on the predicted flood magnitude and arrival time, relevant departments can take appropriate measures to reduce property losses such as infrastructure, farmland, and houses.

[0084] Furthermore, the present invention can also provide data support for the formulation and rehearsal of emergency plans, thereby improving the speed and efficiency of emergency response, and is therefore of great significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 A schematic flow chart of a flash flood forecasting method based on mountain pond flood regulation coupling according to the present invention;

[0086] Figure 2 Another flow chart of the flash flood forecasting method based on the coupling of mountain pond flood regulation of the present invention;

[0087] Figure 3 Schematic diagram of the geographical location of the mountain pond and village in an embodiment of the present invention;

[0088] Figure 4 A corresponding curve diagram of the mountain pond water level and the mountain pond storage capacity of the present invention;

[0089] Figure 5 A schematic diagram of the relationship between the rainfall process, the flood entering the mountain pond, and the flood in the interval basin according to the present invention;

[0090] Figure 6 A curve diagram showing the relationship between the water level of a mountain pond and its discharge capacity according to the present invention;

[0091] Figure 7 A relationship curve diagram of the storage capacity and discharge capacity of the mountain pond of the present invention;

[0092] Figure 8 A schematic diagram of the relationship between the inflow flood process, outflow flood and evolving flood of a mountain pond according to the present invention;

[0093] Figure 9 A schematic diagram of the flood forecasting process according to the present invention. DETAILED DESCRIPTION

[0094] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0095] Rather, the present invention encompasses any alternatives, modifications, equivalents, and solutions that fall within the spirit and scope of the present invention as defined by the claims. Furthermore, to facilitate a better understanding of the present invention, certain specific details are described in detail below in the detailed description of the present invention. Those skilled in the art will be able to fully understand the present invention without these details.

[0096] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention pertains. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0097] like Figure 1 As shown, the first specific embodiment of the flash flood forecasting method based on the mountain pond flood control coupling of the present invention is as follows:

[0098] A flash flood forecasting method based on mountain pond flood control coupling includes the following steps:

[0099] Step 1: Obtain basic information of mountain ponds in the area to be predicted;

[0100] Step 2: Process the basic information of the mountain pond to obtain the initial water level data of the mountain pond;

[0101] Step 3: Couple the rainfall data, evaporation data, and initial water level data of the mountain pond to obtain the outflow of the mountain pond;

[0102] Step 4: Evolve the outflow of the mountain pond to the downstream forecast section to obtain the predicted flood process in the downstream area, and realize the mountain flood forecast based on the coupling of mountain pond flood control.

[0103] The second specific embodiment of the flash flood forecasting method based on mountain pond flood control coupling of the present invention is as follows:

[0104] A flash flood forecasting method based on mountain pond flood control coupling includes the following steps:

[0105] Step 1: Obtain the basic geographic information of the area to be predicted, which includes basic watershed information, basic mountain pond information, and basic mountain pond information. The method for obtaining the basic geographic information of the area to be predicted is as follows:

[0106] First, digital elevation data for small watersheds involving mountain ponds was imported. Then, depressions were filled in the small watershed digital elevation data. Based on the resulting grid, flow directions and river channels were extracted. Based on the topological relationships between mountain ponds, river channels, and villages, the mountain pond reservoir basin and inter-basin basins were divided. Finally, the hydrological analysis module was used to extract geographic characteristics such as basin area, river channel length, and river gradient.

[0107] Step 2: Process the basic information of the watershed, the basic information of the mountain pond, and the basic information of the mountain pond to obtain the initial water flow data of the watershed, the mountain pond, and the mountain pond.

[0108] Step three: Couple the rainfall data, evaporation data, and initial water flow data to obtain the outflow of the mountain pond.

[0109] Step 4: Evolve the outflow of the mountain pond to the downstream forecast section to obtain the predicted flood process in the downstream area, and realize the mountain flood forecast based on the coupling of mountain pond flood control.

[0110] The third specific embodiment of the flash flood forecasting method based on mountain pond flood control coupling of the present invention is as follows:

[0111] A flash flood forecasting method based on the coupling of mountain pond flood control includes water inflow forecasting for the mountain pond reservoir area and interval, calculation of the mountain pond discharge capacity, determination of the mountain pond dispatching rules, mountain pond flood control calculation, and evolution of the flood discharge from the mountain pond.

[0112] The mountain pond reservoir area and interval water inflow forecast is used to calculate mountain pond inflow floods and interval floods. It describes the hydrological phenomena through four levels of calculation, namely: the first level of evapotranspiration calculation, the second level of runoff calculation, the third level of water source division and the fourth level of confluence calculation.

[0113] The present invention uses a hydrological model and a mountain pond flood regulation calculation method to predict floods in small watersheds in mountainous areas, and divides the watershed above the forecast section into a mountain pond reservoir watershed and an interval watershed, considering the runoff generation and convergence processes of the two areas respectively.

[0114] Shan ponds are typically located in the upper reaches of a river basin, storing 10,000 to 100,000 cubic meters of water. They typically have a catchment area of ​​0.5 to 5 square kilometers. Due to the steep terrain within the basin, rainwater can quickly accumulate and form floods.

[0115] For mountain pond reservoir basins, this method couples the calculation of the outflow from the mountain pond with the mountain pond flood control algorithm, overcoming the shortcomings of existing methods that fail to consider the impact of mountain ponds on flash flood processes. This method comprehensively considers the impact of the initial water level, initial reservoir capacity, and scheduling rules on the mountain pond flood control algorithm, making the results more realistic.

[0116] Therefore, the present invention can accurately predict the flood process in small watersheds in mountainous areas, improve the accuracy of flood forecasting, shorten the flood forecasting operation time, and improve the level of support for flood control decision-making.

[0117] In this example, in the evapotranspiration calculation layer, according to the water storage characteristics and soil moisture conditions of the soil, evapotranspiration is divided into three layers for consideration and calculation, including the upper evapotranspiration , lower layer evaporation and deep evapotranspiration .

[0118] In the runoff calculation layer, the input is the net rainfall after deducting evapotranspiration. , the output is the watershed flow Due to the spatial distribution differences in the topography of small watersheds, the soil tension water storage capacity within the watershed is also different. The model approximates the distribution of the watershed soil water storage capacity as a parabola. The water storage capacity distribution curve describes the water storage capacity and runoff characteristics of the soil at different moisture levels. The mathematical equation of the soil water storage capacity distribution curve is:

[0119]

[0120] Where: is the maximum storage capacity of tension water in the basin, is the tension water storage capacity at any point in the basin, Indicates that the tension water storage capacity is less than or equal to The ratio of the value to the basin area, is the distribution coefficient of the tension water storage capacity curve of the basin.

[0121] Flow rate The calculation formula is:

[0122]

[0123] Where: The net rainfall is obtained by deducting the evapotranspiration from the rainfall. is the average water storage capacity of the basin, is the soil moisture content at the initial moment.

[0124] In the water source division calculation layer, the flow rate calculated by the flow calculation layer is Entering the mountain pond, when the mountain pond is full, the overflowing water forms surface runoff The water flowing out from the side outlet is the soil flow , the water flowing out from the bottom outlet is underground runoff , ground diameter Calculated by the following formula:

[0125]

[0126] Where: is the average free water storage in the basin, is the free water storage, is the ordinate corresponding to the initial free water storage, is the maximum free water storage capacity of the basin, is the free water storage distribution curve index, is the ratio of runoff area.

[0127] Subsurface flow runoff , underground runoff The calculation formula is:

[0128]

[0129] Where: 、 are the outflow coefficients of subsurface flow and groundflow, respectively.

[0130] In the final runoff calculation layer, considering the different flow characteristics between the slope area and the river area, the runoff calculation is divided into two stages: the slope runoff stage and the river network runoff stage. Directly flows into the river network. Through linear mountain ponds to form soil flow , underground runoff The underground runoff is stored in the linear mountain pond The calculation formula is:

[0131]

[0132]

[0133] Where: is the soil flow at time t, is the underground runoff at time t, is the soil flow runoff at time t, is the underground runoff at time t, is the soil flow recession coefficient, is the groundwater recession coefficient, The unit conversion factor for converting rainfall into flow.

[0134] The three types of runoff converge into the river network together to form the final flow process , the calculation formula is:

[0135]

[0136] The discharge capacity of a mountain pond is the sum of the discharge capacity of the spillway and the discharge capacity of the culvert.

[0137] The spillway discharge capacity is calculated using the weir flow formula, which is as follows:

[0138]

[0139] In the formula, is the discharge flow of the spillway, is the pier side shrinkage coefficient, is the flooding coefficient, is the total clear width of the overflow weir, To take into account the weir crest head of the approaching flow velocity, is the water head above the weir, is the acceleration due to gravity, is the flow coefficient, is the upstream slope correction factor.

[0140] The discharge capacity of the culvert is calculated using the hole flow formula, which is as follows:

[0141]

[0142] In the formula, is the discharge flow of the culvert, is the flow coefficient, is the drainage culvert area, The orifice head taking into account the approaching flow velocity.

[0143] For mountain ponds, free discharge is generally adopted. For this method, it is necessary to select the starting water level and starting outflow flow of the mountain pond, and then perform the mountain pond flood control calculation.

[0144] In this embodiment, the method for performing mountain pond flood control calculation is as follows, including the following steps:

[0145] Step 1: Generate high-resolution digital elevation data (DEM) from the mountain pond surveying data. Slice the DEM horizontally at intervals of 1.0 meters. Calculate the trapezoidal volume between adjacent water levels layer by layer, and accumulate the reservoir capacity corresponding to different water levels. Combined with the discharge capacity of the mountain pond corresponding to different water levels, the reservoir capacity of different mountain ponds is obtained. Corresponding discharge capacity .

[0146] Step 2: Determine the time step , used for subsequent calculations.

[0147] Step 3: is the independent variable, For the dependent variable, create a set of discrete data points . Construct a Substitute each data point into the polynomial equation using the Shantang fitting function to obtain a linear equation system, which is expressed as follows:

[0148]

[0149]

[0150]

[0151] Where, , ,...... are the coefficients of the equation system, , ...... are the variables of the equations, , ...... is the constant of the equation system.

[0152] The linear equations are written in matrix form as follows:

[0153]

[0154] Where: Design Matrix yes The matrix expression is as follows:

[0155]

[0156] The expression of the coefficient vector is as follows:

[0157]

[0158] The expression of the observation vector is as follows:

[0159]

[0160] Use the least squares method to solve the coefficients, which are expressed as follows:

[0161]

[0162] Polynomial degree ‌ from low degree Start to increase gradually and use the residual sum of squares (RSS) to evaluate the fitting effect, select the most appropriate polynomial degree, and make the polynomial as close as possible to the given discrete data points .

[0163] The residual sum of squares is used to measure the fitting error of the model, and the calculation formula is:

[0164]

[0165] in: For the The actual value of the observation point, For the model The predicted value of each observation point, is the total number of data points.

[0166] The present invention uses a polynomial interpolation function to fit the flood control auxiliary line, and replaces the original map query method with a method of calling the fitting function, which can greatly improve the map query efficiency and is easy to implement through programming.

[0167] Step 4: Obtain the inflow flow of the mountain pond at the beginning and end of the period from the flood process of the mountain pond 、 ;

[0168] Step 5: Get the outflow flow of Shantang at the beginning of the period , substitute the polynomial interpolation function and calculate the intermediate variable ;

[0169] Step 6. Substitute the above terms into the rewritten water balance equation, which is expressed as follows:

[0170]

[0171] in, is the storage capacity of the mountain pond at the beginning of the period, is the storage capacity of the mountain pond at the end of the period, It is the outbound flow at the end of the period.

[0172] Then, we get the intermediate variable ;

[0173] Step 7: Set the intermediate variable Substitute the value of into the Shantang fitting function to obtain the outflow flow at the end of the period ;

[0174] Step 8: The outbound flow at the end of the period calculated in the above steps As the initial outbound flow of the next period , repeat steps 4 to 7 for iterative calculation, complete the mountain pond flood control calculation, and obtain the mountain pond outflow process.

[0175] In this embodiment, the method for evolving the outflow of the mountain pond to the downstream forecast section to obtain the forecast flood process of the downstream area is as follows:

[0176] Mountain ponds are a certain distance away from downstream villages or forecast sections, and the outflow from the mountain ponds needs to evolve for a period of time before reaching the downstream villages or forecast sections. For mountain rivers, the flow process line basically does not deform, but only shifts over time. Therefore, the key issue is to calculate the evolution time. The evolution time can be obtained by dividing the river length by the average flow velocity of the river. The average flow velocity of the river is calculated using the Eagleson Bras method for calculating hydrodynamic parameters. This method takes into account natural geographical factors such as river width and river slope that affect flow velocity, and can reflect the nonlinear effect of flow velocity through changes in net rainfall intensity. The calculation formula is:

[0177]

[0178]

[0179] In the formula is the net rain intensity; is the watershed area; For the width of the river; is the slope of the river; is the Manning roughness coefficient, which is generally taken as 0.025.

[0180] Evolution time of outbound flow process line The calculation formula is:

[0181]

[0182] In the formula is the length of the river.

[0183] Shift the outflow flow from the mountain pond Time, and superimposed with the interval flood, to obtain the predicted flood process of the downstream villages or forecast sections.

[0184] like Figure 2 As shown, the fourth specific embodiment of the flash flood forecasting method based on the mountain pond flood control coupling of the present invention is as follows:

[0185] A flash flood forecasting method based on mountain pond flood control coupling includes the following steps:

[0186] Step 1: Obtain basic information on the watershed, including the watershed area, hydrological characteristics, and geological conditions; obtain basic information on mountain ponds, including the size of the ponds, water level, storage capacity curve, and flood discharge structures.

[0187] Step 2: Based on the measured or predicted rainfall and evaporation data, forecast the flood process of mountain ponds and the flood process of interval basins.

[0188] Step 3: Based on the size of the mountain pond flood discharge structure, use the weir flow formula and the hole flow formula to calculate the mountain pond discharge capacity and obtain the mountain pond water level-discharge capacity relationship curve.

[0189] Step 4: Determine the mountain pond dispatching procedures and obtain the starting water level and starting outflow of the mountain pond, i.e. the starting outflow.

[0190] Step 5: Use the graphical method to calculate the flood control of the mountain pond and construct a mountain pond fitting function that is as close as possible to the given discrete data points. The coordinates of the discrete data points are .

[0191] Then, the outflow flow rate at the beginning of the period is taken as the outflow flow rate at the beginning of the period, and the outflow flow rate at the end of each period is iteratively calculated to finally obtain the outflow flow process of the entire period.

[0192] Step 6: Calculate the average velocity of the river using the Eagleson Bras method. Divide the length of the river by the average velocity to obtain the evolution time of the outflow from the mountain pond. Shift the outflow flow from the mountain pond Time, and superimposed with the interval flood, to obtain the predicted flood process of the downstream villages or forecast sections.

[0193] An embodiment of the present invention provides a flash flood forecasting method based on the coupling of a hydrological model and mountain pond flood control, which uses a hydrological model and a mountain pond flood control calculation method to forecast floods in small watersheds in mountainous areas. The present invention improves the shortcoming of the original method that does not consider the impact of mountain ponds on flash floods, and can improve the accuracy of flood forecasting and the level of support for flood control decision-making.

[0194] Accurate flash flood forecasts allow relevant departments to issue early warnings, prompting residents to evacuate promptly and minimizing casualties. Based on the predicted flood magnitude and arrival time, relevant departments can take appropriate measures to mitigate damage to infrastructure, farmland, housing, and other property. Accurate forecasts also provide data support for the development and rehearsal of emergency plans, improving the speed and efficiency of emergency responses, and are therefore of great significance.

[0195] In this embodiment, the mountain pond flood control algorithm uses a static reservoir capacity flood control algorithm. The mountain pond volume and water level change linearly within a time period, and the mountain pond discharge is a function of the pond storage capacity. Therefore, the continuity equation can be converted into a finite difference water balance equation. The entire flood inflow and outflow process is divided into several time periods. Within each time period, the difference between the average inflow and outflow equals the change in the mountain pond capacity.

[0196] Since the outflow and storage capacity of the mountain pond at the end of each period are unknown, it is necessary to use the mountain pond discharge and mountain pond water storage capacity relationship Therefore, the calculation method of mountain pond flood control is to calculate the water balance equation and discharge volume. and water storage capacity The present invention uses a polynomial interpolation function to fit the flood control auxiliary line, replacing the original map query method with a fitting function call, which can greatly improve the map query efficiency and is easy to implement through programming.

[0197] A specific embodiment of applying the present invention to forecast flash floods in a village:

[0198] There is a mountain pond built upstream of a village. Flash flood forecast is conducted with the village as the forecast section. The basic information of the mountain pond is obtained, which includes the following:

[0199] The length of a river from Shantang to the village is 3.7 km and the width is 10 m. The relative position is as follows: Figure 3 The Shantang reservoir area has a drainage area of ​​7.4 The drainage area between the mountain pond and the village is 6.2 .

[0200] The main components of the mountain pond are the main body of the mountain pond, the spillway, and the water diversion tunnel. The spillway is located on the right side of the main body of the mountain pond. The inlet weir top elevation is 281.10m. It is a practical overflow weir with a weir width of 11m. The water diversion tunnel is located in the mountain on the right side of the main body of the mountain pond. It has a circular cross-section, a hole diameter of 0.6m, a total length of 168.30m, an inlet bottom elevation of 257.26m, and an outlet bottom elevation of 240.76m. The water level and reservoir capacity curve of the mountain pond is as follows: Figure 4 shown.

[0201] The rainfall process is a measured rainfall in July 2022, and the rainfall duration and forecast duration are both 24 hours. The evaporation is the average evaporation of the month. The rainfall process and the flood process of the mountain pond and the flood process of the interval basin are as follows. Figure 5 shown.

[0202] According to the dimensions of the spillway and water diversion tunnel of the mountain pond, the weir flow formula and the hole flow formula are used to calculate the discharge capacity of the mountain pond at different water levels. Then the discharge capacities of the spillway and water diversion tunnel are added together to obtain the relationship curve between the mountain pond water level and discharge capacity, as shown in the figure below: Figure 6 shown.

[0203] According to the mountain pond dispatching regulations, the flood control method of the mountain pond is determined to be free open discharge. The starting water level of the mountain pond is 281.10m, and the starting outflow is 0.

[0204] In this embodiment, a graphical method is used to perform mountain pond flood control calculation, which includes the following steps:

[0205] Step 1: Obtain the capacity of different mountain ponds based on the water level-mountain pond capacity curve and the water level-discharge capacity relationship curve Corresponding discharge capacity , The relationship curve is as follows Figure 7 shown.

[0206] Step 2: Determine the time step For 1 hour.

[0207] Step 3: Use the polynomial interpolation function to fit and establish a relationship curve. The expression is as follows:

[0208]

[0209] make , take the polynomial degree as 3, and the fitted polynomial interpolation function is:

[0210]

[0211] The residual sum of squares (RSS) is 0.0005, indicating a high degree of fit.

[0212] Step 4: Obtain the inflow flow of the mountain pond at the beginning and end of the period from the flood process of the mountain pond 、 .

[0213] Step 5: Get the outflow flow of Shantang at the beginning of the period , substitute Relationship curve, query to get .

[0214] Step 6. Substitute the above terms into the rewritten water balance equation:

[0215]

[0216] get .

[0217] Step 7: The value query relationship curve , get the outbound flow at the end of the period .

[0218] Step 8: The outbound flow at the end of the period calculated in the above steps As the initial outbound flow of the next period , repeat steps 4 to 7 for iterative calculation, complete the mountain pond flood control calculation, and obtain the mountain pond outflow process.

[0219] The process of flood inflow and outflow from mountain ponds is as follows Figure 8 As shown, from Figure 8 From the data, we can see that the peak flow of the flood out of the mountain pond is 11% lower than the flood in of the mountain pond, and the flood process is shifted back by 1 hour as a whole.

[0220] Then, the digital elevation data (DEM) of the basin was imported using geographic information system software, and the digital elevation data was filled. Based on the grid after filling, the flow direction and river channel were extracted, and the river channel slope S was obtained to be 0.01, the Manning roughness coefficient n was taken as 0.025, and the average net rainfall intensity of this rainfall was 40 The average flow velocity of the river was calculated using the Eagleson Bras method. , evolution time It is 1680 seconds, about 30 minutes.

[0221] Therefore, the flood process line of the mountain pond outflow is shifted backward by 30 minutes and added to the interval flood process to finally obtain the forecast flood process of the downstream forecast section. Figure 9 shown.

[0222] An embodiment of a device applying the method of the present invention:

[0223] An electronic device comprising:

[0224] one or more processors;

[0225] a storage device for storing one or more programs;

[0226] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned mountain flood forecasting method based on mountain pond flood regulation coupling.

[0227] A computer medium embodiment of the method of the present invention:

[0228] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned mountain flood forecasting method based on mountain pond flood regulation coupling.

[0229] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field can still modify or replace the specific implementation methods of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A flash flood forecasting method based on mountain pond flood control coupling, characterized by: The following steps are involved: Step 1: Obtain basic information of mountain ponds in the area to be predicted; Step 2: Process the basic information of the mountain pond to obtain the initial outflow flow and initial water level data of the mountain pond under different working conditions; Step 3: Couple the rainfall data, evaporation data, and initial water level data of the mountain pond to obtain the outflow of the mountain pond; It includes the following: Obtaining rainfall data based on measured rainfall information or forecast rainfall information; Calculate the flood process of mountain ponds based on rainfall and evaporation data; Based on the initial water level data of the mountain pond and the size of the mountain pond flood discharge structure, the discharge capacity of the mountain pond is calculated, and the discharge capacity relationship curve is obtained to represent the discharge capacity corresponding to different reservoir capacities of the mountain pond; Carry out flood control calculation according to the discharge capacity relationship curve and time step to obtain the flood control auxiliary line; The flood control auxiliary line is fitted using a polynomial interpolation function to obtain the mountain pond fitting function; The initial outflow of the mountain pond is used as the outflow of the mountain pond at the beginning of the period, and it is substituted into the mountain pond fitting function. The end flow of each period is iteratively calculated, and finally the outflow of the mountain pond and the complete outflow process of the mountain pond are obtained. The method to obtain the flood control auxiliary line is as follows: Determine the time step and construct the independent and dependent variables based on the discharge capacity relationship curve; The independent variable is the discharge capacity, and the dependent variable is the coupling of the mountain pond capacity, the discharge capacity and the time step. Based on the independent and dependent variables, a set of discrete data points is established; Connect the discrete data points to obtain the flood control auxiliary line; The final method to obtain the outflow flow of the mountain pond and the complete outflow flow process of the mountain pond is as follows: Step 1: From the flood process of the mountain pond, obtain the mountain pond inflow flow at the beginning of the period and the mountain pond inflow flow at the end of the period; Step 2: Obtain the outflow flow of the mountain pond at the beginning of the period, and substitute the outflow flow of the mountain pond at the beginning of the period into the mountain pond fitting function to obtain the intermediate variable; Step 3: Substitute the intermediate variables and the inflow into the mountain pond at the beginning and end of the period into the water balance equation to obtain new intermediate variables. Step 4: Substitute the new intermediate variable into the mountain pond fitting function to obtain the mountain pond outflow at the end of the period; Step 5: Using the mountain pond outflow at the end of the time period calculated in the above steps as the mountain pond outflow at the beginning of the next time period, repeating steps 2 to 4 for iterative calculation to complete the mountain pond flood control calculation for the entire calculation cycle, and obtaining the mountain pond outflow and the entire mountain pond outflow process; Step 4: Evolving the outflow from the mountain pond to the downstream forecast section, obtaining the predicted flood process in the downstream area, and realizing the mountain flood forecast based on the coupling of mountain pond flood regulation; The method for obtaining the predicted flood process in the downstream area is as follows: Obtaining rainfall data based on measured rainfall information or forecast rainfall information; Calculate flood processes in interval basins based on rainfall data, mountain pond outflow and evaporation data; Determine the interval flood flow of the downstream forecast section according to the interval basin flood process; Calculate the average flow velocity of the river using the hydrodynamic parameter calculation method; Divide the river channel length by the average river flow velocity to obtain the evolution time of the mountain pond outflow; After shifting the evolution time of the mountain pond outflow, it is superimposed with the interval flood flow to obtain the predicted flood process of the downstream area.

2. The method for predicting mountain torrents based on mountain pond flood control coupling according to claim 1, characterized in that: Step 1: The method for obtaining basic information of mountain ponds in the area to be predicted is as follows: The flood discharge method of the mountain pond is free open discharge; Based on the free discharge method, obtain the size of the mountain pond, the water level mountain pond storage capacity curve and the mountain pond flood discharge structure; Based on the location of the mountain pond, determine the basic information of the watershed, including the watershed area, hydrological characteristics and geological conditions; The basic information of mountain ponds in the area to be predicted is obtained by summarizing the scale of mountain ponds, water level mountain pond storage capacity curves, mountain pond flood discharge structures and basic information of the watershed.

3. The method for predicting mountain torrents based on coupling of mountain pond flood control and flood control as claimed in claim 2, characterized in that: Based on the location of the mountain pond, the method for determining the basic information of the watershed is as follows: According to the location of the mountain pond, obtain the digital elevation data of the watershed where the mountain pond is located; Perform depression filling processing on digital elevation data to obtain watershed raster information; Extract water flow direction and river channel information based on watershed raster information; Based on the flow direction and river information of the water area, the topological relationship between the mountain pond, river channel and village is analyzed to obtain the mountain pond reservoir area basin and the interval basin; The basin area, hydrological characteristics and geological conditions are extracted from the mountain pond reservoir area and the inter-area basin to obtain the basic basin information; the hydrological characteristics include the river length and river slope information.

4. The method for predicting mountain torrents based on coupling of mountain pond flood control and flood control according to claim 1, characterized in that: Step 2: Process the basic information of the mountain pond to obtain the initial water level data of the mountain pond as follows: Obtain basic information about mountain ponds; Based on the basic information of the mountain pond, analyze the size, design parameters and historical operation data of the mountain pond to determine the initial outflow flow and initial water level data of the mountain pond under different working conditions; Combined with real-time monitoring data and mountain pond dispatching rules, the initial water level data of the mountain pond is dynamically adjusted.

5. The method for predicting mountain torrents based on coupling of mountain pond flood control and flood control according to claim 1, characterized in that: Based on the initial water level data of the mountain pond and the size of the mountain pond flood discharge structure, the method for calculating the mountain pond discharge capacity and obtaining the discharge capacity relationship curve is as follows: Based on the initial water level data of the mountain pond and the size of the flood discharge structure of the mountain pond, the digital elevation data of the mountain pond is generated, and the digital elevation data of the mountain pond is horizontally sliced ​​to obtain a number of water level slices; Based on several water level slices, calculate the trapezoidal volume between adjacent water levels; The reservoir capacity corresponding to different water levels is obtained by adding up the trapezoidal volumes. Combined with the discharge capacity of the mountain pond corresponding to different water levels, the discharge capacity corresponding to different mountain pond storage capacities is obtained, thereby obtaining the discharge capacity relationship curve.

6. The method for predicting mountain torrents based on coupling of mountain pond flood control and flood control according to claim 5, characterized in that: The polynomial interpolation function is used to fit the flood control auxiliary line. The method to obtain the fitting function is as follows: Use polynomial interpolation function to fit the flood control auxiliary line and obtain the linear equation system: Write the linear equations into matrix form to obtain the Shantang fitting matrix, which includes the design matrix, coefficient vector and observation value vector; Use the least squares method to solve the coefficient vector and obtain the coefficient expression; Based on the coefficient expression, the polynomial degree is gradually increased from the low degree, and the residual sum of squares is used to evaluate the fitting effect of the Shantang fitting matrix to determine the optimal degree of the polynomial; According to the optimal degree of the polynomial, the final Shantang fitting function is determined.

7. A flash flood forecasting system based on mountain pond flood control coupling, characterized by: It includes: one or more processors; a storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the mountain flood forecasting method based on mountain pond flood regulation coupling as described in any one of claims 1 to 6.

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