A dynamic analysis and early warning method for river surface overland flow

Abstract

The present invention relates to the field of intelligent flood control and construction in water environment engineering, and is a dynamic analysis and early warning method suitable for river surface overland flow. The method includes the following steps: analysis of runoff generation and convergence of river sections; analysis of flow in river sections under such non-stable flow conditions affected by the rise and fall of flood waves; deducing the water level of the river section in each period by means of the water level-flow relationship; and after obtaining the water level change process of the section, performing water level analysis between sections. By acquiring data such as surface rainfall, river gradient data, and water level-flow relationship, relevant mechanism research is carried out around small watershed rivers, thereby forming a reliable dynamic analysis system to provide effective basis support for risk warning and decision-making.

Description

Technical Field

[0001] The present invention relates to the field of intelligent flood disaster control construction in water environment engineering, and is a dynamic analysis and early warning method suitable for river surface overland flow. Background Art

[0002] With the rapid development of urbanization, floods and waterlogging disasters occur frequently. The main causes of floods and waterlogging disasters are changes in extreme weather, increased runoff due to hardening of the underlying surface, changes in the heat island effect, low drainage capacity of the pipe network, and the change of land use types from permeable to impermeable surfaces. The eastern part of my country has been severely affected by floods, and surface overland flow caused by rising water levels has occurred frequently. In the existing water environment engineering construction, there are many research works on small watershed hydrological models, most of which are aimed at studying the model mechanism.

[0003] At present, models such as MIKE, SWMM, and HEC are often used to complete the coupling of one-dimensional river channels and two-dimensional hydrodynamic models. Based on multi-source data such as rainfall, geographic elevation, surface underlying surface, water area, and existing municipal infrastructure, hydrological and hydrodynamic processes such as flood peak evolution calculation and hydrological forecasting are carried out. As of now, a set of methods suitable for the dynamic analysis of surface overland flow in rivers has not been formed.

[0004] Although there are hydrological dynamics professional models such as MIKE as the technical support for contemporary intelligent models, and the models with encapsulated mechanisms can better solve the difficult problems of current engineering projects, they are not very targeted and the speed of real-time simulation needs to be improved. Therefore, it is still necessary to accelerate the direct evolution of mechanisms into detailed research.

[0005] In order to better analyze and study the overland flow phenomenon, the overland flow phenomenon formed by the river water level increase under rainfall intensities in different time periods is considered, involving influencing factors such as runoff generation and confluence, normal river water level, flood level, flood peak, levee height, flow momentum, flow state, river gradient, etc., the present invention proposes a dynamic analysis and early warning method suitable for river overland flow. Summary of the invention

[0006] The purpose of the present invention is to provide a dynamic analysis and early warning method suitable for river surface overland flow. By acquiring data such as surface rainfall, river gradient data, water level-flow relationship, etc., relevant mechanism research is carried out around small watershed rivers, thereby forming a reliable dynamic analysis system to provide effective basis support for risk warning and decision-making.

[0007] The technical solution of the present invention is:

[0008] A dynamic analysis method applicable to river surface flow includes the following steps:

[0009] Analysis of runoff generation and confluence of river sections;

[0010] Analysis of flow in a river section under such unsteady flow conditions affected by the ebb and flow of flood waves;

[0011] The water level of the river section in each period is calculated by using the water level-flow relationship;

[0012] After obtaining the cross-section water level change process, the water level analysis between cross-sections is carried out.

[0013] Furthermore, the runoff analysis of the river section includes:

[0014] Step 1) Setting of river sections within the basin;

[0015] Step 2) Calculation of runoff generation and convergence in the interval;

[0016] Step 3) Muskingum method river confluence routing;

[0017] Furthermore, the step 1) sets the river section in the basin to m sections, specifically: according to the geographical environment of the basin itself, the main stream of the river is divided into several units according to the area of ​​equal flow according to the actual project, and each unit sets a corresponding section at its river outlet, the number of sections is set to m, and the length of the river section La between adjacent sections is recorded, where a=1...m.

[0018] Furthermore, the step 2) of calculating the runoff generation and convergence of the interval is a process of calculating the flow of the cross section of the interval by performing the runoff generation and convergence calculation of the sub-basin through the isochrone method, specifically:

[0019] According to the principle of the isochrone method, the net rainfall falling on the basin surface flows out of the basin outlet section in sequence according to the confluence time of each isochrone area. The calculation formula is:

[0020] q i,i+j-1 =0.278r i f i j=1,2,…,n

[0021] Among them, r i is the net rainfall intensity in the i-th period, r i =h / Δt, mm / h; Δt is the confluence time of equal flow lines, h is the elapsed time; f i is the area between the two isochrones at confluence time (j-1)Δt and jΔt, km 2 ; (j-1)Δt is the isocurrent time line of the j-1th segment, jΔt is the isocurrent time line of the jth segment; q i ,i+j-1 is in f i Upper i The outlet cross-sectional flow rate at the end of period i+j-1, m 3 / s; i is the i-th rainfall period, j is the equal flow period, and i+j-1 is the i+j-1th period;

[0022] Assuming that the flow formed by the net rain in each period does not interfere with each other in the confluence process, the flow process of the outlet section is the superposition of the net rain falling on multiple equal flow areas in sequence, then the inflow flow of the section interval in the tth period is Q t :

[0023]

[0024] Where n is a natural number and t is i+j-1.

[0025] Furthermore, the Muskingum method river confluence calculation in step 3 is a process of calculating the flow response of the upstream section outflow at the downstream section by using the Muskingum method, taking into account the channel storage effect of the river, and the specific steps are as follows:

[0026] (1) When the section is the initial section, when a=1, the upstream response is 0, that is:

[0027] Q 区,1,t =Q 1,t

[0028] (2) When the section is not the initial section and a is not 1

[0029] a) Obtain the length of the river channel from section a-1 to section a, La, where a=2, 3, ... m;

[0030] b) Set the characteristic river length la and storage constants Ka and △ta, and calculate the value of the flow weight factor Xa. The calculation formula is as follows:

[0031]

[0032] c) Solve the Muskingum equation for the coefficients, including C 0,a , C 1,a , C 2,a :

[0033]

[0034]

[0035]

[0036] C 2,a +C 1,a +C 0,a =1

[0037] d) The response process of the outflow from section a-1 at section a. When t=t0, let Q a-1 ,t0=Q a,t0, then:

[0038] C 2,a Q a,t-1 +C 1,a Q a-1,t-1 +C 0,a Q a-1,t =Q 响,a,t

[0039] e) Based on this, the response process of water inflow from the upstream section of section a can be calculated.

[0040] Furthermore, the flow analysis of the river section is the flow calculation of the cross-sectional flow process, that is, the superposition of the interval flow and the upstream cross-sectional response value at the same time. The specific formula is as follows:

[0041] Q 区,a,t +Q 响应,a,t =Q a,t

[0042] Among them, Q 区,a,t is the flow of production and exchange in the interval, Q 响应,a,t is the upstream section response value, Q a,t is the actual flow rate of section a.

[0043] Furthermore, the water level of the river section in each period is deduced by the water level-flow relationship, that is, according to the water level-flow relationship, the water level change process at the section is deduced from the flow process of the section, as follows:

[0044] When obtaining the real-time flow change process of the cross section, the change process of the water level over time is obtained based on the water level flow relationship curve:

[0045] f Z-Q (Q a,t )=Z a,t ,

[0046] where f Z-Q (Q a,t ) is the water level-discharge relationship; Z a,t The water level is deep.

[0047] Furthermore, after obtaining the cross-section water level change process, the cross-section water level analysis is performed: according to the linear interpolation method, the water level change value at a certain point between the cross-sections is deduced from the water level process of two adjacent cross-sections:

[0048]

[0049] Among them a is the distance from section a-1 to section a.

[0050] Furthermore, the dynamic analysis method applicable to river overland flow also includes judging the overland flow situation: whether the water level at the point exceeds the warning water level of the dam. If so, it indicates overland flow; if not, it indicates that no overland flow occurs.

[0051] An early warning method for river surface overflow is provided. Based on the above-mentioned dynamic analysis method for river surface overflow, overflow prediction is performed and an early warning is issued when the predicted water level is greater than the warning water level.

[0052] The beneficial effects of the present invention are as follows: since the overall concept of big data + hydrology + geography is adopted, the problem of major disasters that are difficult to predict during river roaming is effectively solved; by utilizing the super computing power of computers and the advantages of big data, the accuracy rate will be raised to a higher level, thereby realizing disaster prevention in a true sense, and making predictions in real time or even in advance.

[0053] The use of the isochrone method and Muskingum method effectively solved the regulation and storage function of the basin, the uneven spatial and temporal distribution of rainfall, and the influence of the river gradient. At the same time, with the help of the water level flow relationship curve, the real-time water level change process of the basin section was obtained. At the same time, according to the linear difference method, the river water level change process was obtained, so as to obtain the situation of overland flow, and through the big data platform and GIS platform, the intuitive visualization of the overland flow was realized.

[0054] The present invention is further described below with reference to the accompanying drawings and embodiments, but is not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A flow chart of a dynamic analysis method applicable to river surface overland flow of the present invention;

[0056] Figure 2 It is a schematic diagram of the isochrone lines of the basin;

[0057] Figure 3 This is a river surface flow map. DETAILED DESCRIPTION

[0058] The present invention provides a dynamic analysis method for river surface overland flow, comprising the following steps: flow generation and convergence analysis of a river section; flow analysis of a river section under the condition of an unstable flow state affected by the rise and fall of flood waves; deducing the water level of the river section in each time period by means of a water level-flow relationship; and after obtaining the water level change process of the section, performing water level analysis between sections.

[0059] The following is a specific description of a dynamic analysis method applicable to river surface flow of the present invention:

[0060] like Figure 1As shown in FIG. 1 , a dynamic analysis method applicable to river surface flow includes the following steps:

[0061] 1. Analysis of runoff generation and confluence of river sections;

[0062] The runoff analysis of the river section includes:

[0063] Step 1) The river section setting in the basin is m sections, specifically: according to the geographical environment of the basin itself, based on the actual project and the area of ​​equal flow, the main stream of the river is divided into several units, and each unit is set with a corresponding section at its river outlet. The number of sections is set to m, and the length of the river section La between adjacent sections is recorded, where a = 1...m.

[0064] Step 2) Calculation of runoff generation and convergence in the interval;

[0065] The calculation of interval runoff is to calculate the flow of the section of the interval by using the equal flow time line method to calculate the runoff of the sub-basin. Specifically:

[0066] According to the principle of isocurrent time line method, Figure 2 As shown in the figure, the net rainfall falling on the basin surface flows out of the basin outlet section in sequence according to the confluence time of each equal flow area. The calculation formula is:

[0067] q i,i+j-1 =0.278r i f i j=1,2,…,n

[0068] Among them, r i is the net rainfall intensity in the i-th period, r i =h / Δt, mm / h; Δt is the confluence time of equal flow lines, h is the elapsed time; f i is the area between the two isochrones at confluence time (j-1)Δt and jΔt, km 2 ; (j-1)Δt is the isocurrent time line of the j-1th segment, jΔt is the isocurrent time line of the jth segment; q i ,i+j-1 is in f i Upper i The outlet cross-sectional flow rate at the end of period i+j-1, m 3 / s; i is the i-th rainfall period, j is the equal flow period, and i+j-1 is the i+j-1th period;

[0069] Assuming that the flow formed by the net rain in each period does not interfere with each other in the confluence process, the flow process of the outlet section is the superposition of the net rain falling on multiple equal flow areas in sequence, then the inflow flow of the section interval in the tth period is Q t :

[0070]

[0071] Where n is a natural number and t is i+j-1.

[0072] Step 3) Muskingum method river confluence routing;

[0073] For the basin, except for the initial section, the flow process at other sections is the result of the superposition of the interval inflow and the outflow of the previous section at the same time through the flattening of the river channel. The interval inflow is deduced by the isochrone method, and the response of the outflow of the previous section can be calculated using the Muskingum method, taking into account the gradient of the river channel.

[0074] Muskingum method river confluence routing is to consider the channel storage effect of the river channel and use Muskingum method to deduce the flow response process of the upstream section outflow at the downstream section. The specific steps are as follows:

[0075] (1) When the section is the initial section, when a = 1, considering that the initial section has no upstream section and is the first section set in the basin, the upstream response is 0, that is:

[0076] Q 区,1,t =Q 1,t

[0077] (2) When the section is not the initial section and a is not 1

[0078] a) Obtain the length of the river channel from section a-1 to section a, La, where a=2, 3, ... m;

[0079] b) Set the characteristic river length la and storage constants Ka and △ta, and calculate the value of the flow weight factor Xa. The calculation formula is as follows:

[0080]

[0081] c) Solve the Muskingum equation for the coefficients, including C 0,a , C 1,a , C 2,a :

[0082]

[0083]

[0084]

[0085] C 2,a +C 1,a +C 0,a =1

[0086] d) The response process of the outflow from section a-1 at section a. When t=t0, let Q a-1 ,t0=Q a ,t0, then:

[0087] C 2,a Q a,t-1 +C 1,a Q a-1,t-1 +C 0,a Q a-1,t =Q 响,a,t

[0088] e) Based on this, the response process of water inflow from the upstream section of section a can be calculated.

[0089] 2. Analysis of flow in river sections under the unsteady flow conditions affected by the rise and fall of flood waves;

[0090] The river flow analysis is the flow calculation of the cross-sectional flow process, that is, the superposition of the interval flow and the upstream cross-sectional response value at the same time. The specific formula is as follows:

[0091] Q 区,a,t +Q 响应,a,t =Q a,t

[0092] Among them, Q 区,a,t is the flow of production and exchange in the interval, Q 响应,a,t is the upstream section response value, Q a,t is the actual flow rate of section a.

[0093] 3. Use the water level-flow relationship to deduce the water level of the river section in each period; that is, according to the water level-flow relationship, the water level change process at the section is deduced from the flow process of the section, as follows:

[0094] When obtaining the real-time flow change process of the cross section, the change process of the water level over time is obtained based on the water level flow relationship curve:

[0095] f Z-Q (Q a,t )=Z a,t ,

[0096] where f Z-Q (Q a,t ) is the water level-discharge relationship; Z a,t The water level is deep.

[0097] 4. After obtaining the cross-section water level change process, perform water level analysis between cross-sections: According to the linear interpolation method, the water level change value at a certain point between cross-sections is deduced from the water level process of two adjacent cross-sections:

[0098]

[0099] Among them a is the distance from section a-1 to section a.

[0100] 5. Judgment of overland flow: Whether the water level at this point exceeds the warning water level of the dam. If it does, it indicates overland flow; if it does not, it means that no overland flow occurs.

[0101] Considering that the river embankment has its own warning water level, and the water level change process at each location can be deduced, when the river water level exceeds the embankment warning water level, overland flow occurs, and the duration of the overland flow can be known based on the water level change process. Figure 3 A and B represent two different positions.

[0102] The present invention also provides an early warning method suitable for river surface overflow, which predicts overflow based on a dynamic analysis method suitable for river surface overflow, and issues an early warning when the predicted water level is greater than the warning water level.

[0103] This early warning method for river overland flow, before the early warning, first stores the Muskingum method parameters and the isocurrent time line method parameters of each section in the database, when real-time rainfall occurs, the big data platform reads the real-time rainfall data, reads the interval and the Muskingum method parameters from the database, calculates the cross-section water level process in real time, and then obtains the total water level process of the river, and displays the cross-section water level process with the help of a visualization data platform, and displays the specific overland flow occurrence and duration of the river with the help of a GIS platform. The big data platform, the visualization data platform and the GIS platform are all existing technologies, among which the GIS platform is a geographic information system (Geographic Information System, referred to as GIS), which is software that can provide storage, display and analysis functions of geographic data, mainly including data input and editing, data management, data operation, data display and output, etc.

[0104] The database of the early warning method for river surface overflow in the present invention adopts a combination of MySQL relational database and column database to achieve efficient query, specifically:

[0105] First, a MySQL relational database and a column-based database were established for river surface overflow warning data, and a mapping relationship was created based on the key fields of the two databases.

[0106] Second, when writing rainfall data, the data is written to the two databases twice, and based on the mapping relationship, the data value in the column-based database is modified synchronously every time the MySQL data changes, to ensure the uniqueness of the data.

[0107] Third, the platform's business functions are all queried from the MySQL relational database. When performing online analysis of rainstorm floods and surface runoff prediction calculations, the amount of data will be very large, so data queries are performed in batches from the columnar database based on key fields.

[0108] After querying, data partitioning and traversal based on DBMLList (custom array name) array collection

[0109] 1) Hourly rainfall during heavy rain in the river section

[0110] 2) Determine the cross-sectional flow rate

[0111] 3) Determine the water level of the section

[0112] The early warning method of the present invention combines the characteristics of the existing data storage optimization query method and program code set to effectively improve the efficiency of system early warning decision-making.

[0113] Since the monitoring of river surface overland flow involves many factors, mainly considering rainfall, river section, flow velocity, drop, soil quality, distance, etc., the traditional manual monitoring method is inefficient and the accuracy is difficult to guarantee, so the idea of ​​big data + artificial intelligence is introduced. The accumulation of a large amount of historical data can extract the conversion relationship between the water level and flow of the river, which can be accurate to different river interfaces, and the downstream water level can be estimated according to the upstream rainfall, which is of great significance for flood prevention and disaster relief.

[0114] The parts and English abbreviations not described in detail in this embodiment are well-known technologies or common means in this industry and are not described here one by one.

Claims

1. A dynamic analysis method suitable for river surface flow, characterized in that: The steps include: Analysis of runoff generation and confluence of river sections, including: Step 1) Setting of river sections within the basin: According to the geographical environment of the basin itself, the main stream of the river is divided into several units according to the area of ​​equal flow time based on the actual project. Each unit is set with a corresponding section at its river outlet. The number of sections is set to m, and the length of the river section between adjacent sections is recorded, where a = 1...m; Step 2) Calculation of runoff generation and convergence in the interval Through the isochrone method, the flow process of the section of the interval is obtained by calculating the flow generation and convergence of the sub-basin, which is specifically: According to the principle of the isochrone method, the net rainfall falling on the basin surface flows out of the basin outlet section in sequence according to the confluence time of each isochrone area. The calculation formula is: q i，i+j-1 =0.278r i f i j=1,2,…,n Among them, r i is the net rainfall intensity in the i-th period, r i =h / Δt, mm / h; Δt is the confluence time of equal flow lines, and h is the elapsed time; f i is the area between the two isochrones at confluence time (j-1)Δt and jΔt, km 2 ; (j-1)Δt is the isocurrent time line of the j-1th section, jΔt is the isocurrent time line of the jth section; q i，i+j-1 For i Upper i The outlet cross-sectional flow rate at the end of period i+j-1, m 3 / s; i is the i-th rainfall period, j is the equal flow period, and i+j-1 is the i+j-1th period; Assuming that the flow formed by the net rain in each period does not interfere with each other in the confluence process, the flow process of the outlet section is the superposition of the net rain falling on multiple equal flow areas in sequence, then the inflow flow of the section interval in the tth period is Q t : Where n is a natural number, and t is i+j-1; Step 3) Muskingum method river flow routing Considering the channel storage function of the river channel, the flow response process of the upstream section outflow at the downstream section is deduced by Muskingum method; Analysis of flow in a river section under such unsteady flow conditions affected by the ebb and flow of flood waves; The water level of the river section in each period is calculated by using the water level-flow relationship; After obtaining the cross-section water level change process, the water level analysis between cross-sections is carried out: according to the linear interpolation method, the water level change value at a certain point between cross-sections is deduced from the water level process of two adjacent cross-sections: Where Z a，t For water depth; 11a is the distance from section a-1 to section a from section a-1: Judgment of overland flow: whether the water level at this point exceeds the warning water level of the dam. If it does, it indicates overland flow; if it does not, it means that no overland flow occurs.

2. A dynamic analysis method for river surface flow according to claim 1, characterized in that: The specific steps of step 3) Muskingum method river confluence calculation are as follows: (1) When the section is the initial section, when a=1, the upstream response is 0, that is: Q 区，1，t =Q 1，t ; (2) When the section is not the initial section and a is not 1 a) Obtain the length of the river channel from section a-1 to section a, La, where a=2, 3, ... m; b) Set the characteristic river length la and storage constants Ka and △ta, and calculate the value of the flow weight factor Xa. The calculation formula is as follows: c) Solve the Muskingum equation for the coefficients, including C 0，a , C 1，a , C 2，a : d) The response process of the outflow from section a-1 at section a. When t=t0, let Q a-1 , t0=Q a , t0, then: C 2，a Q a，t-1 +C 1，a Q a-1，t-1 +C 0，a Q a-1，t =Q 响，a，t e) Based on this, calculate the response process of water inflow from the upstream section of section a.

3. The dynamic analysis method for river surface flow according to claim 1, characterized in that: The river flow analysis is the flow calculation of the cross-sectional flow process, that is, the superposition of the interval flow and the upstream cross-sectional response value at the same time. The specific formula is as follows: Q 区，a，t +Q 响应，a，t =Q a，t Among them, Q 区，a，t is the flow of production and exchange in the interval, Q 响应，a，t is the upstream section response value, Q a，t is the actual flow rate of section a.

4. A dynamic analysis method for river surface flow according to claim 1, characterized in that: The water level of the river section in each period is deduced by the water level-flow relationship, that is, according to the water level-flow relationship, the water level change process at the section is deduced from the flow process of the section, specifically as follows: after obtaining the real-time flow change process of the section, the water level change process over time is obtained according to the water level-flow relationship curve: f Z-Q (Q a，t )=Z a，t , where f Z-Q (Q a，t ) is the water level-discharge relationship; Z a，t The water level is deep.

5. An early warning method for river surface overland flow, characterized by: Based on a dynamic analysis method suitable for river surface overflow as described in any one of claims 1 to 4, overflow prediction is performed, and an early warning is issued when the predicted water level is greater than the warning water level.

6. The early warning method for river surface overtopping according to claim 5 is characterized by: This early warning method is applicable to river surface overflow. Before the early warning, the Muskingum method parameters and the isocurrent time line method parameters of each section are stored in the database. When real-time rainfall occurs, the big data platform reads the real-time rainfall data, reads the interval and Muskingum method parameters from the database, calculates the cross-section water level process in real time, and then obtains the total water level process of the river. The cross-section water level process is displayed with the help of a visualization data platform, and the specific occurrence and duration of surface overflow in the river are displayed with the help of a GIS platform.

7. The early warning method for river surface overtopping according to claim 5 is characterized by: The database used for the early warning method of river surface overflow uses a combination of MySQL relational database and column database to achieve efficient query, specifically: First, a MySQL relational database and a column-based database were established for river surface overflow warning data, and a mapping relationship was created based on the key fields of the two databases. Second, when writing rainfall data, the data is written to the two databases twice, and based on the mapping relationship, the data value in the column-based database is modified synchronously every time the MySQL data changes, to ensure the uniqueness of the data. Third, the platform's business functions are all queried from the MySQL relational database. When performing online analysis of rainstorm floods and surface runoff prediction calculations, data queries are performed in batches from the columnar database based on key fields.

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