Method for determining the maximum scouring / deposition flow level of runoff riverbed

Abstract

The present invention discloses a method for determining the maximum scouring / deposition flow level of a runoff riverbed. The method comprises the following steps: selecting the inlet and outlet control hydrological stations of the study river section, obtaining the daily inlet water flow, inlet sediment load, and outlet sediment load of the study river section; calculating the average inlet water flow Q per meter day of each inlet control hydrological station. Wm‑in , average inlet sediment load Q Sm‑in and the average inlet water flow Q Wm‑in ; The average inlet sediment load Q of each inlet control hydrological station in a certain period of time Sm‑in The sum of the average sediment discharge Q at each outlet control hydrological station in the corresponding time period Sm‑out The sum of the difference; the scour / deposition intensity △Q for each time period Sm A Pettit test is performed on the ordered series of corresponding flow levels to determine the maximum scouring flow level or the maximum sedimentation flow level. The present invention can quickly obtain the flow level range for scouring / sedimentation and the maximum scouring / sedimentation flow level of the studied river section, with the advantages of low data collection difficulty and a fast and intuitive judgment method.

Description

Technical Field

[0001] The present invention relates to the technical field of river dynamics, and in particular to a method for determining the maximum scouring / deposition flow level of a runoff riverbed. Background Art

[0002] With the intensification of human activities, river damming and sediment retention have altered downstream water and sediment conditions. Consequently, the construction of downstream river regulation projects, waterway engineering, docks, and other water-related projects requires a clear understanding of the development of river erosion. River topography surveys are far less frequent than water and sediment measurements. Using water and sediment measurement data in place of topographic analysis can effectively improve analysis efficiency, provide a more accurate understanding of the overall evolution of river channels, and provide technical support for related project design and reservoir operation.

[0003] The fundamental cause of river scouring and sedimentation is the exchange of sediment between river water and the riverbed. When sediment from the water settles on the riverbed, the riverbed experiences sedimentation. When sediment from the riverbed begins to enter the water and subsequently migrates downstream, the river channel experiences scouring. Reservoir regulation can alter the outflow process, thereby varying the intensity of scouring and sedimentation in the river section, thereby maintaining river stability and safeguarding engineering safety.

[0004] Different flow levels cause different scour and sedimentation intensities in different river sections. Existing techniques for analyzing and understanding these scour and sedimentation intensities often rely on mathematical models to calculate the variations in scour and sedimentation intensity caused by different flow processes. However, in practice, the calibration and calculation of mathematical models require the collection of extensive topographic data, which presents drawbacks such as difficult data collection, complex calculations, and long computational cycles, making them extremely inconvenient for practical engineering applications. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a method for determining the maximum scouring / deposition flow level of the runoff riverbed, which can relatively quickly determine the maximum scouring flow level or maximum deposition flow level of the studied river section, providing technical support for the construction of river management projects and water-related projects.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for determining the maximum scouring / deposition flow level of a runoff riverbed, which is particularly characterized in that it includes the following steps:

[0007] S1) selecting each inlet and outlet control hydrological station of the study river section, obtaining the daily inlet water flow and inlet sediment load of the study river section from each inlet control hydrological station; obtaining the daily outlet sediment load of the study river section from each outlet control hydrological station;

[0008] S2) Take m days as a time period and use the sliding average method to calculate the average inlet water flow Q of each inlet control hydrological station every m daysWm-in and the average inlet sediment load Q Sm-in ; Calculate the average outlet sediment discharge Q per m day at each outlet control hydrological station Sm-out ; and the average inlet water flow Q in the same period Wm-in , average inlet sediment load Q Sm-in , average export sediment load Q Sm-out Association binding;

[0009] S3) The study section is taken as a closed interval, and the average inlet sediment load Q of each inlet control hydrological station in a certain time period is calculated. Sm-in The sum of the average sediment discharge Q at each outlet control hydrological station in the corresponding time period Sm-out The difference is the scour / deposition intensity △Q in the corresponding time period Sm , then △Q Sm =Q Sm-in -Q Sm-out ; The average inlet water flow Q of each inlet control hydrological station in a certain period of time Wm-in The sum is considered as the flow level, and the scouring / deposition intensity △Q of each time period within the statistical time period is calculated. Sm One-to-one correspondence with the traffic level in the same period;

[0010] S4) Scour / deposition intensity △Q for each time period Sm Perform a Pettit test on the order series composed of corresponding flow levels to determine the maximum flushing flow level or the maximum sedimentation flow level;

[0011] The steps of the Pettit test are as follows:

[0012] The scour / deposition intensity data series x with n samples is constructed into the following ordered series:

[0013]

[0014] in,

[0015]

[0016] If the flow level sequence t satisfies,

[0017] A t =Max|s k |(k=2,3,…,n)

[0018] Then it is said that there is a mutation point at point t, and point t is the flow level corresponding to the extreme point, which is the flow level corresponding to the maximum scouring amount or sedimentation amount, called the maximum scouring flow level or the maximum sedimentation flow level;

[0019] Where,

[0020] x i is the scouring / deposition intensity value in time period i,

[0021] x j is the scouring / deposition intensity value in time period j,

[0022] k is the number of values ​​of scour / deposition intensity,

[0023] S k As the test indicator,

[0024] t is the flow level,

[0025] A t It is the maximum value of scouring or sedimentation.

[0026] Furthermore, in S1), each inlet and outlet control hydrological station includes a control hydrological station for the branching and confluence of the study river section.

[0027] Furthermore, in S2), m takes a value of 15, with 15 days being a time period.

[0028] Furthermore, in S3), the scouring / deposition intensity ΔQ within the statistical time period is calculated. Sm Arrange them in ascending order according to the corresponding traffic level.

[0029] Furthermore, in S4), when there is a mutation point at point t, the statistic is calculated

[0030]

[0031] If P≤0.5, the extreme point is considered to be statistically significant.

[0032] Where,

[0033] A t is the extreme value of the test indicator,

[0034] P is the statistic.

[0035] Furthermore, in S4), when there is no mutation point at point t, it indicates that the scouring / deposition intensity increases or decreases monotonically with the increase of flow level. At this time, the extreme point in the statistical data is taken as the maximum scouring / deposition flow level. When the study section is dominated by scouring within the range of each flow level, the extreme point is called the point corresponding to the maximum scouring flow level; when the study section is dominated by siltation within the range of each flow level, the extreme point is called the point corresponding to the maximum siltation flow level.

[0036] Furthermore, in S4), for the study river sections with severe scouring, the flow level with the most severe scouring is found, and through technical means, the occurrence time and frequency of the maximum scouring flow level are reduced, thereby achieving the purpose of reducing river scouring; for the study river sections with serious siltation, the flow level with the most serious siltation is found, and through technical means, the occurrence time and frequency of the maximum siltation flow level are reduced, thereby achieving the purpose of reducing river siltation.

[0037] Furthermore, in S4), for the study river sections with severe erosion, it is necessary to promptly and effectively protect the easily collapsed shorelines of the river sections to ensure the stability of the river flow and the safety of flood control projects; for the study river sections with serious siltation, dredging should be combined to ensure the safety of navigation, or sand mining areas should be arranged to rationally plan and utilize the silted sediment.

[0038] The advantages of the present invention are:

[0039] 1. This invention focuses on the scouring / silting that occurs in river sections due to the interaction of water and sediment, which causes deep channel erosion, beach siltation, and shoreline collapse. It establishes a simple statistical relationship between the identification of scouring / silting in the study section and flow changes, and obtains the flow level range and maximum scouring / silting flow level of the river section. This can effectively determine the short-term scouring / silting trend of the study section, providing theoretical support for the construction of related projects in the study section and reservoir operation to improve the scouring / silting situation in the river section.

[0040] 2. The present invention first uses the inlet and outlet sediment transport data and inlet water flow data of the control hydrological station to obtain the scouring / deposition intensity ΔQ per unit time period. Sm and the corresponding flow level, and then calculate the scour / deposition intensity △Q of each time period within the statistical time period Sm One-to-one correspondence with the corresponding flow level, and finally the scouring / deposition intensity △Q of each time period Sm Perform the Pettit test to determine the maximum flushing flow level or the maximum sedimentation flow level;

[0041] 3. The present invention analyzes the two different results of the Pettit test (with mutation points and without mutation points) respectively. For the flow level with mutation points, the extreme point is the point corresponding to the river flow level when the scouring / deposition intensity is the largest. When the river section is dominated by scouring within the range of each flow level, the extreme point is called the point corresponding to the maximum scouring flow level. When the river section is dominated by deposition within the range of each flow level, the extreme point is called the point corresponding to the maximum deposition flow level. For the flow level without mutation points, it shows that the scouring / deposition intensity increases or decreases monotonically with the change of flow level. At this time, the point corresponding to the maximum flow level in the statistical data is the extreme point. When the river section is dominated by scouring within the range of each flow level, the extreme point is called the point corresponding to the maximum scouring flow level. When the river section is dominated by deposition within the range of each flow level, the extreme point is called the point corresponding to the maximum deposition flow level.

[0042] 4. For river sections with severe scouring, the present invention uses the Pettit test to find out the flow level with the most severe scouring. It can reduce the time and frequency of the maximum scouring flow level by means of upstream reservoir regulation and storage, reduce river scouring, and timely and effectively protect the easily collapsed shorelines of such river sections to ensure the stability of the river and the safety of flood control projects. For river sections with serious siltation, the Pettit test is used to find out the flow level with the most severe siltation. For navigable river sections, it can combine upstream reservoir scheduling and other means to reduce the time and frequency of the maximum siltation flow level and reduce siltation in the waterway. It can also combine appropriate dredging to ensure navigation safety. It can also properly arrange sand mining areas and rationally plan and utilize the silted sediment.

[0043] The method for determining the maximum scouring / deposition flow level of a runoff riverbed of the present invention can quickly obtain the flow level range of scouring / deposition in the studied river section, as well as the maximum scouring / deposition flow level. It has the advantages of low difficulty in data collection, a fast, intuitive and simple determination method, and real-time adjustment of the determination results according to the monitoring data. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flow chart of the present invention;

[0045] Figure 2 is the result of judging the existence of a mutation point in the embodiment (the river section is mainly silted);

[0046] Figure 3 is the result of judging whether there is a mutation point in the embodiment (the scour is the main river section);

[0047] Figure 4 This is the result of judging that there is no mutation point in the embodiment (scour river section 1);

[0048] Figure 5 This is the judgment result that there is no mutation point in the embodiment (scour river section 2). DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0051] The present invention aims to study the scouring / silting that occurs in river sections under the interaction of water and sand, thereby causing deep trough deepening, beach siltation, shoreline collapse and other phenomena. A simple statistical relationship is established between the judgment of scouring / silting in the river section and the flow change, and the flow level range and maximum scouring / silting flow level of the river section scouring / silting are obtained. Therefore, the short-term scouring / silting trend of the river section can be effectively judged, providing theoretical support for the construction of related projects in the river section and the reservoir scheduling to improve the scouring / silting situation of the river section.

[0052] like Figure 1 As shown, the method for determining the maximum scouring / deposition flow level of a runoff riverbed of the present invention comprises the following steps:

[0053] S1) Selecting the inlet and outlet control hydrological stations of the study river section respectively, obtaining the daily inlet water flow and inlet sediment load of the study river section from each inlet control hydrological station; obtaining the daily outlet sediment load of the study river section from each outlet control hydrological station.

[0054] Specifically, each inlet and outlet control hydrological station includes a control hydrological station for the branch and confluence of the study river section, and the flow data is obtained to select the control hydrological station for the branch and confluence of the study river section.

[0055] S2) Take m days as a time period and use the sliding average method to calculate the average inlet water flow Q of each inlet control hydrological station every m days Wm-in and the average inlet sediment load Q Sm-in ; Calculate the average outlet sediment discharge Q per m day at each outlet control hydrological station Sm-out ; and the average inlet water flow Q in the same period Wm-in , average inlet sediment load Q Sm-in , average export sediment load Q Sm-out Association binding.

[0056] Preferably, m is set to 15, and 15 days is taken as a time period. The average inlet water flow rate every 15 days is QW15-in The average inlet sediment load is Q S15-in , the average export sediment volume is Q S15-out , and Q W15-in , Q S15-in and Q S15-out Association binding.

[0057] During the statistical period, if the sum of the average inlet sediment load of each inlet control hydrological station is greater than the sum of the average outlet sediment load of each outlet control hydrological station, the study river section is called a siltation river section; if the sum of the average inlet sediment load of each inlet control hydrological station is less than the sum of the average outlet sediment load of each outlet control hydrological station, the study river section is called an erosion river section.

[0058] S3) The study section is taken as a closed interval, and the average inlet sediment load Q of each inlet control hydrological station in a certain time period is calculated. Sm-in The sum of the average sediment discharge Q at each outlet control hydrological station in the corresponding time period Sm-out The difference is the scour / deposition intensity △Q in the corresponding time period Sm , then △Q Sm =Q Sm-in -Q Sm-out ; The average inlet water flow Q of each inlet control hydrological station in a certain period of time Wm-in The sum is considered as the flow level, and the scouring / deposition intensity △Q of each time period within the statistical time period is calculated. Sm One-to-one correspondence with the corresponding traffic level.

[0059] Preferably, the scouring / deposition intensity ΔQ within the statistical time period is calculated. Sm Arrange them in ascending order according to the corresponding traffic level.

[0060] S4) Scour / deposition intensity △Q for each time period Sm The Pettit test is performed on the ordered series composed of corresponding flow levels to determine the maximum flushing flow level or the maximum sedimentation flow level.

[0061] The present invention first uses the inlet and outlet sediment transport data and inlet water flow data of the control hydrological station to obtain the scouring / deposition intensity ΔQ in a unit time period. Sm and the corresponding flow level, and then calculate the scour / deposition intensity △Q of each time period within the statistical time period Sm One-to-one correspondence with the corresponding flow level, and finally the scouring / deposition intensity △Q of each time period Sm Perform the Pettit test to determine the maximum flushing flow level or the maximum sedimentation flow level.

[0062] The Pettit test method steps are as follows:

[0063] The scour / deposition intensity data series x with n samples is constructed into the following ordered series:

[0064]

[0065] in,

[0066]

[0067] If the flow level sequence t satisfies,

[0068] A t =Max|s k |(k=2,3,…,n)

[0069] Then it is said that there is a mutation point at point t, and point t is the flow level corresponding to the extreme point, which is the flow level corresponding to the maximum scouring amount or sedimentation amount, called the maximum scouring flow level or the maximum sedimentation flow level;

[0070] Where,

[0071] x i is the scouring / deposition intensity value in time period i,

[0072] x j is the scouring / deposition intensity value in time period j,

[0073] k is the number of values ​​of scour / deposition intensity,

[0074] S k As the test indicator,

[0075] t is the flow level,

[0076] A t is the extreme value of the test indicator.

[0077] Specifically, when the study section is dominated by scouring within the range of each flow level, the extreme point is called the point corresponding to the maximum scouring flow level; when the study section is dominated by silting within the range of each flow level, the extreme point is called the point corresponding to the maximum silting flow level. Figure 2 The figure shows the results of the flow level-scouring and sedimentation determination of a river section from 2004 to 2008. There is a mutation point at 34,000 m in the river section. 3 / s, the amount of sedimentation in the river section corresponding to this flow level is the largest. Figure 3 As shown, the results of the flow level-scouring and sedimentation determination of a river section from 2009 to 2017 are shown. There is a mutation point at 21000m in the river section. 3 / s, the river section corresponding to this flow level has the largest scouring volume.

[0078] In S4), when there is a mutation point at point t, calculate the statistic

[0079]

[0080] If P≤0.5, the extreme point is considered to be statistically significant.

[0081] Where,

[0082] A t is the extreme value of the test indicator,

[0083] P is the statistic.

[0084] In addition, when there is no mutation point at point t, it indicates that the scouring / deposition intensity increases or decreases monotonically with the increase of flow level. At this time, the extreme point in the statistical data is taken as the point corresponding to the maximum flow level. When the study section is dominated by scouring at each flow level, the extreme point is called the point corresponding to the maximum scouring flow level; when the study section is dominated by siltation at each flow level, the extreme point is called the point corresponding to the maximum siltation flow level.

[0085] In this embodiment, Figure 4 The above is the result of judging the flow level and erosion and deposition of a river section from 2004 to 2008. There is no mutation point in the river section. k The value increases monotonically, with a maximum flow rate of 42000m 3 / s, the scouring capacity of the river section is the largest. Figure 5 The above is the result of judging the flow level and erosion and deposition of a river section from 2009 to 2017. There is no mutation point in the river section. k The value increases monotonically, and the maximum flow level is 45000m 3 / s, the scouring volume of the river section is the largest.

[0086] In S4), for the study sections with severe scouring, find out the flow level with the most severe scouring, and use technical means to reduce the occurrence time and frequency of the maximum scouring flow level, so as to achieve the purpose of reducing river scouring; for the study sections with serious siltation, find out the flow level with the most serious siltation, and use technical means to reduce the occurrence time and frequency of the maximum siltation flow level, so as to achieve the purpose of reducing river siltation.

[0087] Specifically, for study sections with severe scouring, upstream reservoir regulation and storage can be used to reduce the duration and frequency of maximum scouring flow levels. For study sections with severe scouring, timely and effective protection of vulnerable shorelines is required to ensure river stability and the safety of flood control projects. For study sections with severe siltation, appropriate sand mining areas should be arranged and the accumulated sediment should be rationally planned and utilized. For navigable sections, upstream reservoir regulation and other measures can be combined to reduce the duration and frequency of maximum siltation flow levels, reduce siltation within the waterway, and combine appropriate dredging to ensure navigation safety.

[0088] The method for determining the maximum scouring / deposition flow level of a runoff riverbed of the present invention can quickly obtain the flow level range of scouring / deposition in the studied river section, as well as the maximum scouring / deposition flow level. It has the advantages of low difficulty in data collection, a fast, intuitive and simple determination method, and real-time adjustment of the determination results according to the monitoring data.

[0089] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for determining the maximum scouring / deposition flow level of a runoff riverbed, characterized in that: The steps include: S1) selecting each inlet and outlet control hydrological station of the study river section, and obtaining the daily inlet water flow and inlet sediment load of the study river section from each inlet control hydrological station; Obtain the daily sediment discharge at the outlet of the study section from each outlet control hydrological station; S2) Take m days as a time period and use the sliding average method to calculate the average inlet water flow Q of each inlet control hydrological station every m days Wm-in and the average inlet sediment load Q Sm-in ; Calculate the average outlet sediment discharge Q per m day at each outlet control hydrological station Sm-out ; and the average inlet water flow Q in the same period Wm-in , average inlet sediment load Q Sm-in , average export sediment load Q Sm-out Association binding; S3) The study section is taken as a closed interval, and the average inlet sediment load Q of each inlet control hydrological station in a certain time period is calculated. Sm-in The sum of the average sediment discharge Q at each outlet control hydrological station in the corresponding time period Sm-out The difference is the scour / deposition intensity △Q in the corresponding time period Sm , then △Q Sm =Q Sm-in -Q Sm-out ; The average inlet water flow Q of each inlet control hydrological station in a certain period of time Wm-in The sum is considered as the flow level, and the scouring / deposition intensity △Q of each time period within the statistical time period is calculated. Sm One-to-one correspondence with the corresponding traffic level; S4) Scour / deposition intensity △Q for each time period Sm Perform a Pettit test on the order series composed of corresponding flow levels to determine the maximum flushing flow level or the maximum sedimentation flow level; The steps of the Pettit test are as follows: The scour / deposition intensity data series x with n samples is constructed into the following ordered series: in, If the flow level sequence t satisfies, A t =Max|s k |(k=2,3,…,n) Then it is said that there is a mutation point at point t, and point t is the flow level corresponding to the extreme point, which is the flow level corresponding to the maximum scouring amount or sedimentation amount, called the maximum scouring flow level or the maximum sedimentation flow level; Where, x i is the scouring / deposition intensity value in time period i, x j is the scouring / deposition intensity value in time period j, k is the number of values ​​of scour / deposition intensity, S k As the test indicator, t is the flow level, A t is the extreme value of the test indicator.

2. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 1, characterized in that: In S1), each inlet and outlet control hydrological station includes the control hydrological station of the branch and confluence of the study river section.

3. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 2, characterized in that: In S2), m is set to 15, and 15 days is used as a time period.

4. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 3, characterized in that: In S3), the scouring / deposition intensity △Q within the statistical time period is calculated. Sm Arrange them in ascending order according to the corresponding traffic level.

5. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 1, characterized in that: In S4), when there is a mutation point at point t, calculate the statistic If P≤0.5, the extreme point is considered to be statistically significant. Where, A t is the extreme value of the test indicator, P is the statistic.

6. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 5, characterized in that: In S4), when there is no mutation point at point t, it indicates that the scouring / deposition intensity increases or decreases monotonically with the increase of flow level. At this time, the extreme point in the statistical data is taken as the point corresponding to the maximum flow level. When the study section is dominated by scouring within the range of each flow level, the extreme point is called the point corresponding to the maximum scouring flow level; when the study section is dominated by deposition within the range of each flow level, the extreme point is called the maximum deposition flow level.

7. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 6, characterized in that: In S4), for the study section with severe scouring, find the flow level with the most severe scouring, and use technical means to reduce the occurrence time and frequency of the maximum scouring flow level, so as to achieve the goal of reducing river scouring; For the river sections with serious siltation, we find out the flow level with the most serious siltation, and use technical means to reduce the time and frequency of occurrence of the maximum siltation flow level, so as to achieve the goal of reducing river siltation.

8. The method for determining the maximum scouring / deposition flow level of a runoff riverbed according to claim 7, characterized in that: In S4), for the study sections with severe scouring, it is necessary to promptly and effectively protect the easily collapsed shorelines of the river sections to ensure the stability of the river flow and the safety of flood control projects; for the study sections with serious siltation, dredging should be combined to ensure navigation safety, or sand mining areas should be arranged to rationally plan and utilize the silted sediment.

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