A method for calculating inflow between lakes and rivers

Abstract

The present invention discloses a method for calculating the interval inflow of lakes connected to rivers. The method is characterized in that after constructing a hydrodynamic model consisting of rivers entering the lake, lakes, and rivers leaving the lake, the hydrodynamic model is first calibrated and verified according to the measured data of the hydrological station under the condition of no precipitation; then the hydrological analogy method is used to amplify the measured flow of each hydrological station of the rivers entering the lake as the upper boundary condition, and the simulated lake mouth flow is calculated using the hydrodynamic model and compared with the measured value. When the comparison result is greater than the preset value, the amplification coefficient is adjusted and the simulation comparison is repeated until the simulation comparison result is less than the preset ratio. The simulation is considered accurate. At this time, the sum of the amplified flow of the measured flow of each hydrological station of the rivers entering the lake is the interval inflow. The present invention can better avoid the influence of factors such as the top-up state of lakes connected to rivers and the influence of human activities on the calculation of the inflow of lakes, and can accurately and efficiently calculate the interval inflow value of lakes connected to rivers, thereby better providing guidance and guarantee for flood control in lake areas.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrological flood control, and in particular to a method for calculating inflow between lakes and rivers. Background Art

[0002] River-connected lakes are those connected to rivers, with river water flowing freely into them and vice versa. Large river-connected lakes located in low-lying areas such as plains are susceptible to large inflows during the rainy season or flood season, leading to flooding hazards. Therefore, accurately estimating the inflow of river-connected lakes can help prevent floods.

[0003] Inter-regional inflow (inflow within the same region) for large plain lakes connected to rivers includes the inflow from the catchment area below the hydrological stations of the major rivers flowing into the lake, the area of ​​small catchments flowing into the lake without hydrological stations, and the lake area. Large plain lakes connected to rivers have a dense network of rivers flowing into the lake, with a complex network of waterways. This creates a large runoff-generating and converging area, and they experience uneven rainfall distribution and a shortage of rainfall gauges. During flood season, rivers flowing into lakes are severely affected by topwater flow and by human activities along the lakeshore. Traditional hydrological methods make it difficult to calculate inter-regional inflow for large plain lakes connected to rivers.

[0004] The tailgates of large plain rivers and lakes are densely covered with river networks and crisscrossed with water systems. The rainfall and runoff conditions are complex, making it difficult to calculate the interval inflow using conventional methods. This is mainly manifested in the following aspects: First, for the tailgate area of ​​the lake, 1. The tailgate of the lake is affected by the water level support of the lake area, and there is no stable water level-flow relationship, making it difficult to establish a station for conventional hydrological monitoring; 2. The delta area of ​​the tailgate of the lake has fertile soil, rich in organic matter and minerals, and is an excellent agricultural production area. Human activities are frequent in the interval, and the lakeside area is seriously disturbed by human activities, which brings interference to the interval inflow calculation. The currently commonly used interval inflow calculation methods such as the rainfall runoff coefficient method and the hydrological analogy method cannot solve this problem. The hydrological model method is also difficult to determine the parameters due to the complex interval runoff conditions, and there is no measured data for calibration and verification, which makes the reliability of the hydrological model method questionable. Second, for large plain lakes connected to rivers, the lake area is large, and the interval rainfall runoff cannot be ignored. However, there is uneven rainfall distribution. In addition, due to the vast lake area and limited land area, there are insufficient interval rainfall stations, making it difficult to accurately monitor the lake area rainfall. Current research either does not consider the lake area rainfall runoff, or calculates the lake area water volume based on the average rainfall, which cannot accurately calculate the interval flow. Third, for the river estuaries where lakes connected to rivers flow into the lake, the lake estuaries are supported by the river or even backflow, so there is no stable water level flow relationship at the lake estuaries. The response relationship between the lake estuary flow and the inflow flow is uncertain and the response time is long. The lake area has a changing water surface slope, and it is difficult to invert the inflow process from the lake estuary flow.

[0005] To be more specific, the current research methods for calculating the inflow of a specific interval are usually the following: 1) Runoff coefficient method: The runoff coefficient of the hydrological station is obtained through the hydrological data of a long series of stations. The inflow into the lake generated by the catchment area below the hydrological station is obtained by using the average rainfall in the area × runoff coefficient. The problems and shortcomings of this method are: ① The runoff coefficient is the ratio of the runoff depth to the rainfall depth of the catchment area above a certain control section. This method uses the runoff coefficient of the hydrological station section to represent the runoff coefficient of the estuary section, ignoring the influence of human activities on the interval runoff or the existence of control projects such as reservoirs upstream. The runoff coefficients of the upstream and downstream of the basin may not be consistent; ② The use of average rainfall calculations does not take into account the uneven local distribution of regional rainfall. 2) Hydrological analogy method: Using the principle of similarity of runoff in the same basin, the typical hydrological station in the same basin is used as the reference station. The calculation formula is as follows: Q 河口i =(F 河口i / F 控制站i ) n ×Q 控制站i Among them, Q 控制站i is the measured flow at the i-th river hydrological station, F 控制站i is the controlled catchment area of ​​the i-th river hydrological station, F 河口i is the total area of ​​the i-th river basin, Q 河口 is the inflow into the lake from the i-th river basin, and n is a coefficient, generally taken as 2 / 3. The hydrological analogy method requires relatively uniform distribution of heavy rainfall across the entire basin, with no special regulation or storage effects in the interval. Flood peaks can be corrected and then relocated to the calculated section, with the applicable area within a 20% difference. Problems and shortcomings of this method include: ① It fails to account for uneven rainfall distribution upstream and downstream; situations where there is no rainfall upstream but heavy rainfall in the interval, or where there is a significant regulation and storage effect upstream, resulting in inconsistent runoff conditions between the calculated section and the reference station section; ② The same runoff coefficient method fails to account for dissimilarities in runoff generation upstream and downstream, such as the impact of human activities along the lake and the influence of lake uplift; ③ It fails to consider runoff generation in lake areas and small watersheds with no inflow data. 3) Hydrological Model Method: Numerous basin runoff models are available. For example, scholar Bing Jianping proposed using the rainfall-runoff model (NAM) from Mike11 RR to simulate flow processes in basins without measured flow data from hydrological stations. The problems and shortcomings of this method are: ① The model parameters have no measured data for calibration and verification, and the reliability of the model is questionable; ② The model does not consider the impact of top support and the situation where the interval flow is greatly affected by human interference; ③ The rainfall runoff in the lake area and the small watershed area with no data entering the lake is not considered. Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the existing technology, the technical problem to be solved by the present invention is: how to provide a method for calculating the inflow between lakes connected to rivers, which can better avoid the influence of factors such as the top-up state of lakes connected to rivers and the impact of human activities on the calculation of the flow into the lake, improve the calculation accuracy, and better provide guidance and protection for flood control in lake areas.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for calculating the interval inflow of lakes connected to rivers is characterized by constructing a hydrodynamic model consisting of rivers entering the lake, lakes and rivers leaving the lake, first calibrating and verifying the hydrodynamic model according to the measured data of the hydrological stations during a period without precipitation; then using the hydrological analogy method to amplify the measured flow of each hydrological station of the rivers entering the lake and use it as the upper boundary condition, using the hydrodynamic model to calculate the simulated lake mouth flow and compare it with the measured value, and when the comparison result is greater than a preset value, adjusting the amplification coefficient and repeating the simulation and comparison until the simulation comparison result is less than a preset ratio, and the simulation is considered accurate. At this time, the sum of the amplified flow of the measured flow of each hydrological station of the rivers entering the lake is the interval inflow.

[0009] In this way, after modeling, this method first uses the situation of no precipitation to calibrate and verify the model to ensure its accuracy, and then uses the hydrological analogy method to amplify the inflow for simulation and compare it with the actual detection value. When the simulation is accurate, the interval inflow value can be quickly compared and calculated, which has better calculation accuracy and efficiency.

[0010] Furthermore, the method specifically comprises the following steps:

[0011] 1. Construct a hydrodynamic model consisting of rivers entering the lake, lakes, and rivers leaving the lake. The lake has an estuary connected to the rivers leaving the lake, and the rivers leaving the lake have an upstream section located upstream of the estuary and a downstream section located downstream of the estuary. The upper boundary of the hydrodynamic model is the estuary section of each river entering the lake and the hydrological station section of the upstream section of the rivers leaving the lake (closest to the lake estuary). The lower boundary of the hydrodynamic model is the water level station section of the downstream section of the rivers leaving the lake (closest to the lake estuary). The upper boundary condition of the upstream section of the rivers leaving the lake is input as the measured flow rate of the corresponding hydrological station, and the lower boundary condition of the downstream section of the rivers leaving the lake is input as the measured water level of the corresponding water level station. The upper boundary condition of each river entering the lake is input as the flow rate at the boundary of each river entering the lake. The flow rate at the boundary of each river entering the lake is composed of the measured flow rate at the corresponding hydrological station of each river, the flow rate generated by the basin area below the corresponding hydrological station, and the inflow generated by the lake area and small watersheds entering the lake without hydrological station monitoring, which is allocated to the upper boundary of each river entering the lake according to the ratio of the basin area of ​​each river entering the lake (that is, the inflow between the lakes is allocated to the flow rate at the boundary of each river entering the lake).

[0012] 2. Calibrate and verify the model; compare the simulated lake mouth discharge during the precipitation-free period with the measured lake mouth discharge to achieve model calibration and verification;

[0013] 3. Simulate the flow of a certain flood interval by following the steps below:

[0014] 1) Taking the upper boundary conditions of each river entering the lake as the measured flow at each hydrological station (without adding interval flow), the simulated flow at the lake mouth Q1 is calculated;

[0015] 2) Determine the impact of interval flow on lake mouth flow: Calculate the simulated lake mouth flow Q1 and the measured lake mouth flow Q 实 Error|Q 实 -Q1| / Q 实 When the error is less than the preset ratio (10%), the interval flow can be considered to be basically negligible. When the error is greater than the preset ratio (10%), it means that the interval flow is large and affects the outflow of the lake. In the subsequent steps, the inflow of the lake is amplified and the model simulation is carried out to calculate the interval flow.

[0016] 3) Use the hydrological analogy method to amplify the upper boundary conditions of the rivers entering the lake and simulate the lake mouth flow: Use the hydrological analogy method to amplify the measured flow of each river entering the lake at the hydrological station, estimate the flow of each river into the lake at the mouth, and simulate the estimated flow of each river into the lake as the upper boundary conditions of each river to obtain the simulated lake mouth flow Q2. Determine the difference between the simulated lake mouth flow Q2 and the measured lake mouth flow Q 实 Error|Q 实 -Q2| / Q 实 Is it less than the preset ratio (10%)?

[0017] 4) Calculation of interval flow by hydrological analogy method: When the simulated flow Q2 and the measured flow Q are obtained by hydrological analogy method, 实 Error|Q 实 -Q2| / Q 实 If the ratio is less than the preset ratio (10%), it is considered that the boundary conditions of each river obtained by the hydrological analogy method minus the measured flow of each river hydrological station is the interval flow of each river into the lake; the amplification coefficient K of each river i =(F 河口i / F 控制站i ) n ; In the formula, F 控制站i is the controlled catchment area of ​​the i-th river hydrological station, F 河口i is the total area of ​​the i-th river basin, n is the coefficient; K i It represents the flow amplification coefficient of the i-th river into the lake; the flow in the downstream interval of the i-th river is Q 区间i =(K i -1) × Q 控制站i ; Q in the formula 区间i is the interval flow of the i-th river, Q 控制站i is the measured flow at the i-th river hydrological station; the inflow from the lake interval is Q 区间 =∑Q 区间i =∑(K i -1) × Q 控制站i ;

[0018] 5) Adjust the trial calculation to determine the amplification factor: When the simulated lake outlet flow Q2 obtained by inputting the boundary conditions using the hydrological analogy method is compared with the measured lake outlet flow Q 实 If the error is greater than the preset ratio (10%), adjust the lake flow amplification factor K. i Adjust the upper boundary conditions of the model and re-simulate the lake mouth flow until |Q 实 -Q j | / Q 实 <Preset ratio (10%), (The amplification factor is adjusted j times, the model is simulated j times, Q j is the lake mouth discharge calculated for the jth simulation), it can be considered that the upper boundary conditions of the model inflow are in line with reality, the interval flow estimation is reasonable, and the amplification coefficient K of each river is determined. ij ;

[0019] 6) Calculate the interval flow using the amplification factor determined by trial calculation: When |Q 实 -Q i | / Q 实 <preset ratio (10%), at this time ∑Q 上边界ij -Q 控制站i is the incoming flow rate between intervals; 上边界ij Enter the flow value for the jth adjusted boundary of the estuary of the i-th river, Q 控制站i is the measured flow at the i-th river hydrological station; the inflow from the lake interval is Q 区间 =∑Q 区间i =∑(K ij -1) × Q 控制站i ; where Q 区间 Q is the flow from the lake area. 区间i is the interval flow of the i-th river, K ij is the amplification factor determined after the jth trial calculation for the i-th river, Q 控制站i is the measured discharge at the ith river hydrological station.

[0020] In the above steps, the physical meaning of adjusting the amplification coefficient is as follows: ① The basin hydrological analogy method does not take into account the rainfall inflow into the lake area and the inflow into the small basins around the lake area where no hydrological stations are built; ② Large plain lakes connected to rivers have different rainfall frequencies in the upstream and downstream of the basin and uneven local rainfall distribution; ③ The impact of human activities; the runoff conditions in the basin may be different from those in the upstream.

[0021] The method for adjusting the amplification factor is: when Q2 实 , considering F 湖口 -∑F 河口i Flow generation (inflow generated in lake areas and small watersheds without hydrological monitoring stations, F 湖口 is the drainage area controlled by the lake estuary section (lake estuary hydrological station section), ∑F 河口i ​(The area of ​​the major rivers flowing into the lake is set up with hydrological control stations). The runoff from rainfall in the lake area is calculated by multiplying the area of ​​the lake area by the average rainfall, and is allocated to the upper boundary of each river flowing into the lake according to the ratio of the control area of ​​the river basin flowing into the lake; the runoff from the small watershed in the interval is allocated to each inflow boundary according to the ratio of the control area of ​​the river basin flowing into the lake, in addition to considering the impact of human activities. The inflow of the small watershed in the interval is calculated using the hydrological analogy method, and its reference station is the hydrological station in the adjacent basin. The upper boundary input condition of the model is the sum of the flow rate of each river flowing into the lake at the mouth of the lake amplified by the hydrological analogy method, the flow rate allocated by the rainfall runoff in the lake area, and the flow rate allocated by the small watershed in the interval. The amplification coefficient is the ratio of the above three and the flow rate to the flow rate of the control station. When the sum of the flow rates is used as the input upper boundary condition to simulate the lake mouth flow result Q3 实 , it may be a local heavy rain in the interval basin, and the flow generation frequency of the upper and lower reaches of the basin is different. The amplification coefficient can be appropriately increased according to the rainfall situation and trial calculation can be performed. When the sum flow is the input upper boundary condition, the simulation result of the lake mouth flow is Q3>Q 实 or Q2>Q 实 , which means that the interval inflow is too large. The amplification coefficient is appropriately reduced, and the model calculation is performed given the inflow boundary. The reason for the large interval inflow may be that the interval rainfall is less than that in the upper reaches of the basin, and the influence of human activities in the interval is greater.

[0022] Furthermore, step 2 is specifically as follows: simulate the situation of no precipitation period (almost no flow is generated in the interval of no precipitation period), ignore the incoming flow in the interval as zero, the inflow into the lake at each upper boundary is the measured flow of each corresponding hydrological station, and simulate with the measured flow of the hydrological station in the no precipitation period as the inflow boundary. The flow and water level of the lake mouth section are obtained by simulation calculation, and compared with the measured flow and water level of the hydrological station at the lake mouth. For lakes with water level stations, the measured water level in the lake area can also be compared with the simulated water level results. When the simulated lake mouth flow and water level are consistent with the measured flow and water level of the lake mouth station, and the simulated lake area water level is also consistent with the measured water level, it means that the upper boundary conditions of the model inflow are accurate; the parameter calibration and verification of the model are achieved.

[0023] Furthermore, in step 3, the preset ratio is 10%. If it is too large, the accuracy of the calculation is reduced, and if it is too small, the calculation efficiency is reduced.

[0024] Compared to existing technologies, this solution has the following advantages: 1. It accounts for the uneven distribution of precipitation upstream and downstream of large plain river networks. 2. It considers the uneven distribution of rainfall across lake basins. 3. It considers runoff generated by rainfall in the lake area, the impact of human activities on inflows, and runoff generated by small basins within the lake area. 4. It applies a hydrodynamic model to simulate and compare simulated flow at the lake mouth with measured flow, calibrating and verifying the model to ensure its reliability and address the impact of river and lake top-up.

[0025] ​Therefore, the present invention has the following positive effects: 1) It provides a method for calculating interval inflow; 2) It provides a method for more accurately calculating the amount of water resources entering the lake; 3) It can simulate and calculate the flow rate of multiple historical flood intervals, thereby analyzing the rainfall-runoff coefficient of each sub-basin interval, and supporting the prediction of inflow into the lake.

[0026] In summary, the present invention can better avoid the influence of factors such as the top-supported state of lakes connected to rivers and the impact of human activities on the calculation of lake inflow, and can accurately and efficiently calculate the inflow value of the interval between lakes connected to rivers, thus providing better guidance and guarantee for flood control in lake areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram for illustrating the hydrodynamic model of the present invention.

[0028] Figure 2 It is a schematic diagram for illustrating the flow between lakes of the present invention.

[0029] Figure 3 This is the boundary and station distribution map of the Yangtze River-Poyang Lake two-dimensional hydrodynamic model in the specific implementation example - Panyang Lake example.

[0030] Figure 4 This is a specific implementation example - the Panyang Lake example, showing the flow process diagram of the measured flow at the lake mouth and the simulation results.

[0031] Figure 5 In the specific implementation example - Panyang Lake, the simulation results and simulation error analysis table 1.

[0032] Figure 6 This is a specific implementation example - the Panyang Lake example, the amplification coefficient and interval flow calculation table 2. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to specific embodiments.

[0034] Optimal implementation method: A method for calculating the interval inflow of lakes connected to rivers, which is characterized by constructing a hydrodynamic model consisting of rivers entering the lake, lakes and rivers leaving the lake, first calibrating and verifying the hydrodynamic model according to the measured data of the hydrological stations during the period without precipitation; then using the hydrological analogy method to amplify the measured flow of each hydrological station of the rivers entering the lake as the upper boundary condition, and using the hydrodynamic model to calculate the simulated lake mouth flow and compare it with the measured value. When the comparison result is greater than the preset value, the amplification coefficient is adjusted and the simulation and comparison are repeated until the comparison result is less than the preset ratio, and the simulation is considered accurate. At this time, the sum of the amplified part of the measured flow of each hydrological station of the rivers entering the lake is the interval inflow.

[0035] See also Figure 2This is a schematic diagram of the lake interval inflow of the present invention. In the figure, label ① is the tail river channel entering the lake below the control station of the river entering the lake, label ② represents the lake area, ③ represents the river leaving the lake, ④ represents the cross-section of the hydrological control station of the river entering the lake, ⑤ represents the small watershed entering the lake (referring to the small river) without hydrological station monitoring, and ⑥ represents the interval inflow area, which includes the water collection area of ​​the tail river channel ① below each river entering the lake control station, the water collection area of ​​the small watershed entering the lake without hydrological station monitoring around the lake area, and the area of ​​the lake area ②.

[0036] In this way, after modeling, this method first uses the situation of no precipitation to calibrate and verify the model to ensure its accuracy, and then uses the hydrological analogy method to amplify the inflow for simulation and compare it with the actual detection value. When the simulation is accurate, the interval inflow value can be quickly compared and calculated, which has better calculation accuracy and efficiency.

[0037] Specifically, the method comprises the following steps:

[0038] 1. Construct a hydrodynamic model consisting of rivers entering the lake, the lake, and rivers leaving the lake (see Figure 1 ), the lake has an estuary connected to an outflowing river, and the outflowing river has an upstream section located upstream of the estuary and a downstream section located downstream of the estuary; the upper boundary of the hydrodynamic model is the estuary section of each river entering the lake and the hydrological station section of the upstream section of the outflowing river (closest to the lake estuary), and the lower boundary of the hydrodynamic model is the water level station section of the downstream section of the outflowing river (closest to the lake estuary); the upper boundary condition of the upstream section of the outflowing river is input as the measured flow rate of the corresponding hydrological station, and the lower boundary condition of the downstream section of the outflowing river is input as the measured water level of the corresponding water level station. The upper boundary condition of each inflowing river is input as the flow rate at the boundary of each river entering the lake, and the flow rate at the boundary of each river entering the lake is composed of the measured flow rate at the corresponding hydrological station of each river, the flow rate generated by the basin area below the corresponding hydrological station, and the inflow generated by the lake area and the small basin entering the lake without hydrological station monitoring, which is allocated to the upper boundary of each inflowing river according to the ratio of the basin area of ​​each inflowing river (that is, the inflow between the lake and the lake is allocated to the flow rate at the boundary of each river entering the lake);

[0039] 2. Calibrate and verify the model; compare the simulated lake mouth discharge during the precipitation-free period with the measured lake mouth discharge to achieve model calibration and verification;

[0040] 3. Simulate the flow of a certain flood interval by following the steps below:

[0041] 1) Taking the upper boundary conditions of each river entering the lake as the measured flow at each hydrological station (without adding interval flow), the simulated flow at the lake mouth Q1 is calculated;

[0042] 2) Determine the impact of interval flow on lake mouth flow: Calculate the simulated lake mouth flow Q1 and the measured lake mouth flow Q 实 Error|Q 实 -Q1| / Q实 When the error is less than the preset ratio (10%), the interval flow can be considered to be basically negligible. When the error is greater than the preset ratio (10%), it means that the interval flow is large and affects the outflow of the lake. In the subsequent steps, the inflow of the lake is amplified and the model simulation is carried out to calculate the interval flow.

[0043] 3) Use the hydrological analogy method to amplify the upper boundary conditions of the rivers entering the lake and simulate the lake mouth flow: Use the hydrological analogy method to amplify the measured flow of each river entering the lake at the hydrological station, estimate the flow of each river into the lake at the mouth, and simulate the estimated flow of each river into the lake as the upper boundary conditions of each river to obtain the simulated lake mouth flow Q2. Determine the difference between the simulated lake mouth flow Q2 and the measured lake mouth flow Q 实 Error|Q 实 -Q2| / Q 实 Is it less than the preset ratio (10%)?

[0044] 4) Calculation of interval flow by hydrological analogy method: When the simulated flow Q2 and the measured flow Q are obtained by hydrological analogy method, 实 Error|Q 实 -Q2| / Q 实 If the ratio is less than the preset ratio (10%), it is considered that the boundary conditions of each river obtained by the hydrological analogy method minus the measured flow of each river hydrological station is the interval flow of each river into the lake; the amplification coefficient K of each river i =(F 河口i / F 控制站i ) n ; In the formula, F 控制站i is the controlled catchment area of ​​the i-th river hydrological station, F 河口i is the total area of ​​the i-th river basin, n is the coefficient; K i It represents the flow amplification coefficient of the i-th river into the lake; the flow in the downstream interval of the i-th river is Q 区间i =(K i -1) × Q 控制站i ; Q in the formula 区间i is the interval flow of the i-th river, Q 控制站i is the measured flow at the i-th river hydrological station; the inflow from the lake interval is Q 区间 =∑Q 区间i =∑(K i -1) × Q 控制站i ;

[0045] 5) Adjust the trial calculation to determine the amplification factor: When the simulated lake outlet flow Q2 obtained by inputting the boundary conditions using the hydrological analogy method is compared with the measured lake outlet flow Q 实 If the error is greater than the preset ratio (10%), adjust the lake flow amplification factor K. i Adjust the upper boundary conditions of the model and re-simulate the lake mouth flow until |Q 实 -Qj | / Q 实 <Preset ratio (10%), (The amplification factor is adjusted j times, the model is simulated j times, Q j is the lake mouth discharge calculated for the jth simulation), it can be considered that the upper boundary conditions of the model inflow are in line with reality, the interval flow estimation is reasonable, and the amplification coefficient K of each river is determined. ij ;

[0046] 6) Calculate the interval flow using the amplification factor determined by trial calculation: When |Q 实 -Q i | / Q 实 <preset ratio (10%), at this time ∑Q 上边界ij -Q 控制站i is the incoming flow rate between intervals; 上边界ij Enter the flow value for the jth adjusted boundary of the estuary of the i-th river, Q 控制站i is the measured flow at the i-th river hydrological station; the inflow from the lake interval is Q 区间 =∑Q 区间i =∑(K ij -1) × Q 控制站i ; where Q 区间 Q is the flow from the lake area. 区间i is the interval flow of the i-th river, K ij is the amplification factor determined after the jth trial calculation for the i-th river, Q 控制站i is the measured discharge at the ith river hydrological station.

[0047] In the above steps, the physical meaning of adjusting the amplification coefficient is as follows: ① The basin hydrological analogy method does not take into account the rainfall inflow into the lake area and the inflow into the small basins around the lake area where no hydrological stations are built; ② Large plain lakes connected to rivers have different rainfall frequencies in the upstream and downstream of the basin and uneven local rainfall distribution; ③ The impact of human activities; the runoff conditions in the basin may be different from those in the upstream.

[0048] The method for adjusting the amplification factor is: when Q2 实 , considering F 湖口 -∑F 河口i Flow generation (inflow generated in lake areas and small watersheds without hydrological monitoring stations, F 湖口 is the drainage area controlled by the lake estuary section (lake estuary hydrological station section), ∑F 河口i ​(The area of ​​the major rivers flowing into the lake is set up with hydrological control stations). The runoff from rainfall in the lake area is calculated by multiplying the area of ​​the lake area by the average rainfall, and is allocated to the upper boundary of each river flowing into the lake according to the ratio of the control area of ​​the river basin flowing into the lake; the runoff from the small watershed in the interval is allocated to each inflow boundary according to the ratio of the control area of ​​the river basin flowing into the lake, in addition to considering the impact of human activities. The inflow of the small watershed in the interval is calculated using the hydrological analogy method, and its reference station is the hydrological station in the adjacent basin. The upper boundary input condition of the model is the sum of the flow rate of each river flowing into the lake at the mouth of the lake amplified by the hydrological analogy method, the flow rate allocated by the rainfall runoff in the lake area, and the flow rate allocated by the small watershed in the interval. The amplification coefficient is the ratio of the above three and the flow rate to the flow rate of the control station. When the sum of the flow rates is used as the input upper boundary condition to simulate the lake mouth flow result Q3 实 , it may be a local heavy rain in the interval basin, and the flow generation frequency of the upper and lower reaches of the basin is different. The amplification coefficient can be appropriately increased according to the rainfall situation and trial calculation can be performed. When the sum flow is the input upper boundary condition, the simulation result of the lake mouth flow is Q3>Q 实 or Q2>Q 实 , which means that the interval inflow is too large. The amplification coefficient is appropriately reduced, and the model calculation is performed given the inflow boundary. The reason for the large interval inflow may be that the interval rainfall is less than that in the upper reaches of the basin, and the influence of human activities in the interval is greater.

[0049] During implementation, step 2 is specifically as follows: simulate the situation of no precipitation period (there is almost no flow in the interval of no precipitation period), ignore the incoming flow in the interval as zero, the inflow into the lake at each upper boundary is the measured flow of each corresponding hydrological station, and simulate with the measured flow of the hydrological station in the no precipitation period as the inflow boundary. The flow and water level of the lake mouth section are obtained by simulation calculation, and compared with the measured flow and water level of the hydrological station at the lake mouth. For lakes with water level stations, the measured water level in the lake area can also be compared with the simulated water level results. When the simulated lake mouth flow and water level are consistent with the measured flow and water level of the lake mouth station, and the simulated lake area water level is also consistent with the measured water level, it means that the upper boundary conditions of the model inflow are accurate; the model parameters are calibrated and verified.

[0050] Next, the applicant further illustrates and verifies this method using the Panyang Lake example.

[0051] Based on the implementation of the above specific implementation method, the inflow to Poyang Lake is calculated. First, a hydrodynamic model of the Yangtze River, Poyang Lake, and rivers entering the lake is constructed. The upper boundary condition of the Yangtze River is the measured flow at the Jiujiang Hydrological Station, and the lower boundary is the measured water level at the Pengze Water Level Station. The inflow boundary of the Poyang Lake area is defined by the estuary of the river basin with a hydrological station, such as Figure 3 As shown, the five major rivers entering the lake are Xiuhe River, Ganjiang River, Fuhe River, Xinjiang River, Raohe River (Changjiang River + Le'an River), Qingfeng Mountain Stream (its estuary is very close to Fuhe River and is considered together), and Xihe River also have hydrological station flow data. The controlled drainage area of ​​Poyang Lake estuary is 162,225 km 2 , 7 rivers control a drainage area of ​​153,486 km​2 It accounts for 92.7% of the Hukou controlled basin area, and the 7 river hydrological stations control an area of ​​142,290 km 2 It accounts for 87.7% of the Hukou controlled basin area.

[0052] 1. Based on historical flood data, the model was calibrated and verified using the measured flow at Hukou and the measured water level at Xingzi Station.

[0053] 2 Analysis and calculation of the inflow to the Poyang Lake area during the flood from August 6 to August 25, 2012, showed that the rainfall distribution was uneven.

[0054] 3. Without considering the interval flow, simulate the flood. The simulation results are as follows: Figure 4 , calculate the simulated lake mouth flow Q1 and the measured lake mouth flow Q 实 Relative error such as Figure 5 Table 1.

[0055] 4. The flow of seven major river basins was amplified using the hydrological analogy method. The simulation results are as follows: Figure 4 , calculate the simulated lake mouth flow Q2 and the measured lake mouth flow Q 实 Relative error such as Figure 5 As shown in Table 1, the simulation results are basically within the allowable error range.

[0056] 5. Adjust the magnification factor appropriately. Figure 6 Table 2 shows the simulation results. Figure 4 , the simulated lake mouth flow Q3 and the measured lake mouth flow Q 实 Relative error such as Figure 6 Table 2 shows that the simulation results are basically within the allowable error range, compared with the calculation of lake interval flow using this amplification factor.

[0057] 6 Using the simulation Q3 results corresponding to the inflow boundary, the total inflow value of the Poyang Lake section of this flood is 12843 m 3 / s (see Figure 6 Table 2).

[0058] Therefore, the Poyang Lake example verifies that this method has high accuracy and reliability.

Claims

1. A method for calculating inflow between rivers and lakes, characterized in that: After constructing a hydrodynamic model consisting of rivers entering the lake, the lake, and rivers leaving the lake, the hydrodynamic model was first calibrated and verified using the measured data from the hydrological stations during a period without precipitation. The hydrological analogy method was then used to amplify the measured flow at each hydrological station on each river entering the lake, using this as the upper boundary condition. The simulated lake mouth flow was calculated using the hydrodynamic model and compared with the measured value. When the comparison result was greater than a preset value, the amplification factor was adjusted and the simulation and comparison were repeated until the simulation comparison result was less than a preset ratio, which was considered accurate. At this point, the sum of the amplified portions of the measured flow at each hydrological station on the river entering the lake was the interval flow. When simulating the interval flow: The hydrological analogy method is used to amplify the upper boundary conditions of the rivers entering the lake and simulate the lake mouth flow: the hydrological analogy method is used to amplify the measured flow of each river entering the lake at the hydrological station, and the flow of each river estuary into the lake is estimated. The estimated flow of the river estuary into the lake is used as the upper boundary conditions for each river to simulate and obtain the simulated flow of the lake mouth Q2. The difference between the simulated flow of the lake mouth Q2 and the measured flow of the lake mouth Q2 is judged. 实 Error|Q 实 -Q2| / Q 实 Is it smaller than the preset ratio? The hydrological analogy method is used to calculate the interval flow: when the hydrological analogy method is used to calculate the simulated lake mouth flow Q2 and the measured lake mouth flow Q 实 Error|Q 实 -Q2| / Q 实 If the ratio is less than the preset ratio, it is considered that the boundary conditions of each river obtained by the hydrological analogy method minus the measured flow of each river hydrological station is the interval flow of each river into the lake; the amplification coefficient K of each river i =(F 河口i / F 控制站i ) n ; In the formula, F 控制站i is the controlled catchment area of ​​the i-th river hydrological station, F 河口i is the total area of ​​the i-th river basin, n is the coefficient; K i It represents the flow amplification coefficient of the i-th river into the lake; the flow in the downstream interval of the i-th river is Q 区间i =(K i -1) × Q 控制站i ; Q in the formula 区间i is the interval flow of the i-th river, Q 控制站i is the measured flow at the i-th river hydrological station; the inflow from the lake interval is Q 区间 =∑Q 区间i =∑(K i -1) × Q 控制站i ; Then calculate the interval flow using the amplification factor determined by trial calculation: when |Q 实 -Q i | / Q 实 <Preset ratio, at this time ∑Q 上边界ij -Q 控制站i is the incoming flow rate between intervals; 上边界ij Enter the flow value for the jth adjusted boundary of the estuary of the i-th river, Q 控制站i is the measured flow at the i-th river hydrological station; the inflow from the lake interval is Q 区间 =∑Q 区间i =∑(K ij -1) × Q 控制站i ; where Q 区间 Q is the flow from the lake area. 区间i is the interval flow of the i-th river, K ij is the amplification factor determined after the jth trial calculation for the i-th river, Q 控制站i is the measured discharge at the ith river hydrological station.

2. The method for calculating inflow between rivers and lakes according to claim 1, wherein: This method specifically comprises the following steps:

1. Construct a hydrodynamic model consisting of rivers entering the lake, the lake, and rivers leaving the lake. The lake has an estuary connected to the rivers leaving the lake, and the rivers leaving the lake have an upstream section located upstream of the estuary and a downstream section located downstream of the estuary. The upper boundary of the hydrodynamic model is the estuary section of each river entering the lake and the hydrological station section of the upstream section of the rivers leaving the lake, and the lower boundary of the hydrodynamic model is the water level station section of the downstream section of the rivers leaving the lake. The upper boundary condition of the upstream section of the rivers leaving the lake is input as the measured flow rate of the corresponding hydrological station, and the lower boundary condition of the downstream section of the rivers leaving the lake is input as the measured water level of the corresponding water level station. The upper boundary condition of each river entering the lake is input as the flow rate at the boundary of each river entering the lake. The flow rate at the boundary of each river entering the lake is composed of the measured flow rate at the corresponding hydrological station of each river, the flow rate generated by the basin area below the corresponding hydrological station, and the inflow generated by the lake area and the small watershed entering the lake without hydrological station monitoring, which is allocated to the upper boundary of each river entering the lake according to the ratio of the basin area of ​​each river entering the lake.

2. Calibrate and verify the model; compare the simulated lake mouth discharge during the precipitation-free period with the measured lake mouth discharge to achieve model calibration and verification; 3. The simulation trial calculation of interval flow also includes the following steps: 1) Taking the upper boundary conditions of each river entering the lake as the measured flow at each hydrological station, the simulated flow at the lake mouth Q1 is calculated; 2) Determine the impact of interval flow on lake mouth flow: Calculate the simulated lake mouth flow Q1 and the measured lake mouth flow Q 实 Error|Q 实 -Q1| / Q 实 When the error is less than the preset ratio, it can be considered that the interval flow is basically negligible. When the error is greater than the preset ratio, it means that the interval flow is large and has an impact on the outflow of the lake. In the subsequent steps, the inflow into the lake is amplified and the model simulation is carried out to calculate the interval flow. 3) Adjust the trial calculation to determine the amplification factor: When the simulated lake outlet flow Q2 obtained by inputting the boundary conditions using the hydrological analogy method is compared with the measured lake outlet flow Q 实 If the error is greater than the preset ratio, adjust the lake flow amplification factor K. i Adjust the upper boundary conditions of the model and re-simulate the lake mouth flow until |Q 实 -Q j | / Q 实 <Preset ratio, it can be considered that the upper boundary conditions of the model inflow are in line with reality, the interval flow estimation is reasonable, and the amplification coefficient K of each river is determined. ij .

3. The method for calculating inflow between rivers and lakes according to claim 2, wherein: Step 2 is specifically as follows: simulate the situation of no precipitation period, ignore the interval flow as zero, the inflow at each upper boundary is the measured flow at each corresponding hydrological station, and simulate with the measured flow at the hydrological station in the no precipitation period as the inflow boundary. The flow and water level at the lake mouth section are obtained by simulation and calculation, and compared with the measured flow and water level at the hydrological station at the lake mouth. For lake areas with water level stations, compare the measured water level in the lake area with the simulated water level results. When the simulated lake mouth flow and water level are consistent with the measured flow and water level at the lake mouth station, and the simulated lake area water level is also consistent with the measured water level, it means that the upper boundary conditions of the model inflow are accurate; the parameter calibration and verification of the model are achieved.

4. The method for calculating the inflow between rivers and lakes according to claim 2, wherein: In step 3, the preset ratio is 10%.

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