A long-term design tide process line derivation method

Abstract

This invention discloses a method for estimating long-duration design tidal process lines, comprising: preprocessing and frequency analysis of historical tidal data to obtain the design high tide level, design flood tide range, and design ebb tide range; selecting a typical long-duration tidal process containing the highest tide level, and selecting a "one flood, one ebb" process at a later position as the main tidal type according to the principle of "high tide level - long duration - later high tide level", with the rest being secondary tidal types; using the design high tide level, design flood tide range, and design ebb tide range to perform same-frequency combination design on the main tidal type to obtain the design main tidal type process; using the scaling ratio of the corresponding phase points of the design main tidal type and the measured main tidal type as a benchmark, scaling the secondary tidal types accordingly to obtain the design secondary tidal type processes; and splicing the results to obtain the complete long-duration design tidal process. This invention overcomes the limitation of existing methods that can only deduce "one flood, one ebb" processes and is applicable to the calculation of any long-duration design tidal process.

Description

Technical Field

[0001] This invention relates to the field of design tide level calculation and design tide level process line derivation, and in particular to a method for derivation of long-duration design tide level process lines. Background Technology

[0002] Reliable calculation of design tide levels is crucial for ensuring the safety, economy, and sustainability of engineering structures. It is also the basic basis for determining the elevation and cross-sectional dimensions of major structures in coastal water-related projects, and is a direct factor affecting the safety and cost-effectiveness of water-related projects.

[0003] Domestic and international design standards generally adopt the scaling method of typical tidal processes to derive the design tidal process. For example, in the calculation of the design tidal process in the UK, the highest astronomical tide and the peak value of the swell process are superimposed, and other parts are scaled using the same ratio method to scale the tidal level at each moment of the swell process and superimposed with the typical astronomical tidal process to obtain the entire design tidal process. However, the same ratio scaling can lead to the synchronous rise or fall of low tide and high tide levels. In my country's "Hydrological Calculation Specification for Water Conservancy and Hydropower Projects", the design tidal process is calculated based on the design high tide level (or high and low tide levels) and the corresponding high and low tide levels (or high tide levels). However, under different design standards, the low tide level before or after the highest tide level is a fixed value, which does not match the design return period. Current methods can only calculate the "one rise and one fall" tidal process and cannot derive any given duration, especially the long duration design tidal process, which cannot meet the needs of engineering design for long duration design tidal processes. The fundamental reason why existing technologies have long been unable to solve the problem of calculating long-duration design tidal processes is that:

[0004] First, there is the limitation of ingrained thinking. For a long time, the field of engineering design has formed a design model based on "one rise and one fall" as the basic unit, simplifying the design tidal level process into the morphological control of a single rise and fall tide, and has not yet established a conceptual framework of "overall design of multiple tidal cycles". Under this kind of thinking, long-duration processes are regarded as simple repetitions of multiple "one rise and one fall", ignoring the inherent correlation between different tidal cycles and the coordination of design standards.

[0005] Second, there is the challenge of technical contradictions. Long-duration tidal level design processes typically involve multiple tidal cycles. If the same frequency design standard is used for each tidal cycle, the tidal level design process will be overly conservative and physically unrealizable. If the same frequency design is used only for the tidal cycle where the highest tide level is located, and the other tidal cycles are simply repeated or scaled up, the changing patterns of tidal patterns under different return periods cannot be reflected, and the rationality of the connection between the tidal cycles cannot be guaranteed.

[0006] Third, there is a lack of standardized decomposition criteria. During long-duration tidal events, the impact of each tidal cycle on project safety varies, with the tidal cycle containing the highest tide playing a decisive role, while the other tidal cycles mainly affect the stress distribution and construction arrangements throughout the entire process. However, there is currently no mature theoretical support or methodology for scientifically decomposing long-duration processes into "primary tidal types" and "secondary tidal types" and assigning them different design logics.

[0007] Fourth, the inherent defects of scaling methods. Existing scaling methods all adopt a "global same scaling ratio" or "segmented same scaling ratio" scaling mode, that is, applying the same scaling ratio to all tidal points within a certain time period. This mode cannot solve the core contradiction that "different design standards should be applied to primary and secondary tidal types", and will lead to the synchronous rise of low tide and high tide, which is inconsistent with the physical laws of tidal level changes.

[0008] Therefore, there is an urgent need in this field for a method that can overcome the above-mentioned technical obstacles and scientifically deduce the long-duration design tidal process. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a method for estimating long-duration design tidal process lines, aiming to solve the technical difficulty that existing methods can only estimate short-duration processes of "one rise and one fall," and are not applicable to engineering needs with multiple tidal cycles. Through a differentiated design strategy with the same frequency for the main tidal type and corresponding standards for the secondary tidal type, the high safety standards of the main tidal type and the corresponding standards of the secondary tidal type are coordinated and unified. This overcomes the defect of the scaling method where low and high tides rise simultaneously, making the design tidal process significantly superior to existing methods in terms of both physical rationality and engineering applicability.

[0010] To achieve the objective of this invention, the following technical solution is adopted:

[0011] A method for estimating long-duration design tidal hydrographs includes:

[0012] S1, Data Preprocessing, including:

[0013] Reliability analysis and consistency diagnosis of historical tide data are performed, and series that do not meet consistency requirements are corrected.

[0014] The annual maximum value method was used to select the annual highest tide level for each year, forming an annual highest tide level sample series.

[0015] Using the annual maximum value method and corresponding methods, the annual maximum tidal range, annual maximum ebb tidal range, corresponding tidal range, and corresponding ebb tidal range of each year are selected to form a tidal range sample series.

[0016] Analyze the possibility of the annual highest tide level occurring simultaneously with various tidal ranges, and prioritize the sampling results from the annual maximum value method;

[0017] The Mann-Kendall trend test and Pettt's jump test were used to diagnose the consistency of the annual highest tide level and tidal range series, and the series that did not meet the consistency requirements were reconstructed and corrected.

[0018] Using a sliding window method, with a 5-year time interval, the mean and Cv values ​​were calculated for different sample lengths. When the parameter estimates tended to stabilize as the sample length increased, the series was deemed representative.

[0019] S2, Design Calculation: For the sample series that meets the requirements of consistency and representativeness, frequency curve fitting analysis is performed using Pearson's three-type distribution function and Gumbel's distribution function respectively. The parameters are estimated by combining Bayesian method and visual fitting method. The frequency curve is selected optimally, and the design high tide level, design high tide range, and design low tide range are calculated.

[0020] S3, Selection and breakdown of typical tidal patterns from actual measurements: Select a typical tidal process with a long duration that includes the highest tide level from the actual tidal process. According to the principle of "high tide level - long duration - high tide level later", select a "one rise and one fall" process located later in the entire tidal process as the main tidal pattern, and the rest as secondary tidal patterns.

[0021] S4, Main Tidal Pattern Design: The main tidal pattern is designed by combining the design high tide level, design flood tide range and design ebb tide range at the same frequency to obtain the design main tidal pattern process;

[0022] S5, Secondary Tide Pattern Design: Based on the scaling ratio of the phase points corresponding to the primary tide pattern in the designed primary tide pattern process and the measured typical tide level process, the secondary tide pattern in the measured typical tide level process is scaled accordingly to obtain the designed secondary tide pattern process.

[0023] S6, splicing: splicing the design primary tidal pattern process with the design secondary tidal pattern process to obtain a complete long-duration design tidal level process.

[0024] Furthermore, in S4, the calculation method for the design tide level of the main tide type high tide segment is as follows:

[0025] Determine the high and low tide values ​​before the design high tide level based on the design high tide level and the design tidal range. ;

[0026] Calculate the proportion of the tidal range at each time period of the main tidal phase to the total tidal range. ;

[0027]

[0028] In the formula, This is to measure the tide level values ​​at various times during the flood tide segment corresponding to the main tide pattern of a typical tidal process. Its high and low tide values, Its peak value;

[0029] Calculate the design tide level values ​​for each period during the flood phase of the main tide pattern. for:

[0030]

[0031] In the formula, The high and low tide values ​​for the main tidal type during the high tide period. The high tide level of the main tidal type's high tide segment.

[0032] Furthermore, in S4, the calculation method for the design tide level of the ebb tide segment of the main tide type is as follows:

[0033] The low-low tide value is determined based on the design high tide level and the design low tide range. ;

[0034] Calculate the proportion of the tidal range during each period of the ebb tide phase to the total tidal range during the flood tide. :

[0035]

[0036] Calculate the design tide level values ​​for each time period during the ebb tide phase of the main tide pattern. for:

[0037]

[0038] In the formula, This is the low tide level.

[0039] In S5, the secondary tide design specifically includes:

[0040] Divide the design tide level at each phase point during the design of the main tide pattern by the measured tide level at the corresponding phase point during the measured typical tide level process, and calculate the scaling factor for different phase points of the main tide pattern. ;

[0041] The scaling factor of the tide level at any phase point in the ebb tide segment of the secondary tide pattern is adopted using the scaling factor of the corresponding phase point in the ebb tide segment of the main tide pattern. The scaling factor of the tide level at any phase point in the ebb tide segment of the secondary tide pattern is adopted using the scaling factor of the corresponding phase point in the ebb tide segment of the main tide pattern. The design secondary tide pattern is obtained by calculating the following formula:

[0042]

[0043] In the formula, The design tide level value is for the secondary tide type. This refers to the measured tide level values ​​at the corresponding phase points of the secondary tide pattern during the actual measurement of typical tide levels.

[0044] Furthermore, in S3, the selection of the measured typical tide level process follows the principle of "high tide level - long duration - later high tide level"; where "high tide level" means that the highest tide level in the typical tide level process is close to the design high tide level, "long duration" means that the tide level changes slowly near the highest tide level and the high tide level lasts for a long time, and "later high tide level" means that the highest tide level occurs at a later position in the entire design tide level process.

[0045] Furthermore, in S4, the high and low tide values ​​and the low-low tide value of the main tide type flood tide segment and ebb tide segment are determined independently by the design high tide level, the design flood tide difference, and the design ebb tide difference, respectively. Among them, the high and low tide values ​​before the design high tide level are equal to the design high tide level minus the design flood tide difference, and the low-low tide value after the design high tide level are equal to the design high tide level minus the design ebb tide difference.

[0046] Furthermore, in S6, the junction of the design primary tide pattern process and the design secondary tide pattern process is the starting point and the ending point of the design primary tide pattern process. The tide level value at the junction directly adopts the corresponding tide level value of the design primary tide pattern process to ensure the continuity of the junction point.

[0047] Furthermore, in S1, the corresponding method refers to selecting the tidal range of high tide or low tide corresponding to the annual highest tide level.

[0048] Furthermore, S1 also includes ground settlement correction of historical tide data to ensure consistency between the reference datum and the zero point of the water gauge.

[0049] The beneficial effects of this invention are:

[0050] (1) Breaking through the design limitations of "one rise and one fall". The design concept of "the main tide type has the same frequency and the secondary tide type corresponds" was proposed for the first time, and the long-duration tidal process was designed as an organic whole. This solved the technical problem that the existing methods can only deduce the "one rise and one fall" process and cannot be applied to the needs of multi-tidal cycle engineering.

[0051] (2) The design standards are scientifically allocated between the primary and secondary tide types. The primary tide type adopts a combination of the design high tide level, design flood tide range, and design ebb tide range at the same frequency, concentrating all design risks on the primary tide type that plays a decisive role in the safety of the project; the secondary tide type adopts the scaling factor of the primary tide type for corresponding design, avoiding the problem of excessive conservatism caused by using high recurrence period design for multiple tide cycles.

[0052] (3) Overcoming the inherent defects of the scaling method. The high and low tide levels before the design high tide level are determined by subtracting the design high tide range from the design high tide level, and the low tide level after the high tide level is determined by subtracting the design low tide range from the design high tide level, so that the high and low tide levels match the design return period, avoiding the defects of the existing scaling method where the low tide level rises synchronously with the high tide level or the low tide level remains unchanged.

[0053] (4) Maintain physical consistency of tidal patterns. The scaling factor of each phase point of the secondary tidal pattern is consistent with that of the phase point of the primary tidal pattern, which not only maintains the relative morphology of the secondary tidal pattern, but also ensures the smooth connection with the primary tidal pattern, thus achieving the unity of "morphological fidelity" and "standard coordination".

[0054] (5) Strong engineering applicability. The method and steps are clear and easy to operate. It can be applied to the calculation of design tide process for any given duration and has good application prospects in the calculation of design tide process in water conservancy and hydropower projects. Attached Figure Description

[0055] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0056] Figure 1 This is a schematic diagram of the design tidal process line calculated using the standard method;

[0057] Figure 2 This is a schematic diagram of the results of the long-duration designed tidal process line in an embodiment of the present invention. Detailed Implementation

[0058] The present invention will be further described below with reference to specific embodiments. This is only for the purpose of more clearly illustrating the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0059] This embodiment takes a tidal station at an estuary as an example to provide a method for estimating a long-duration design tidal hydrograph. The method steps are as follows:

[0060] S1, Data Preprocessing, including:

[0061] Reliability analysis and consistency diagnosis were performed on historical tide data, and series that did not meet consistency requirements were corrected. Systematically compiled tide data were used. If land subsidence affected the selected years, land subsidence correction was required to ensure consistency between the reference datum and the zero point of the water gauge.

[0062] The annual maximum value method is used to select the annual tidal peak value for each year. With data from n years, n annual tidal peak values ​​can be obtained, forming an annual tidal peak sample series.

[0063] Using the annual maximum value method and corresponding methods, the annual maximum tidal range, annual maximum ebb tidal range, corresponding tidal range, and corresponding ebb tidal range for each year are selected respectively. With n years of data, n annual maximum tidal range, annual maximum ebb tidal range, corresponding tidal range, and corresponding ebb tidal range can be obtained, forming a sample series of tidal range and ebb tidal range.

[0064] This analysis examines the likelihood of synchronization between the annual highest tide level and the annual maximum tidal range and the annual maximum ebb tide, as well as between the annual highest tide level and the corresponding tidal range and the corresponding ebb tide, under different design standards. If the synchronicity between the annual highest tide level and the corresponding tidal range is not significantly higher than that between the annual highest tide level and the annual maximum tidal range, then, for safety reasons, the annual maximum tidal range series should be prioritized.

[0065] The Mann-Kendall trend test and Pettt's jump test were used to diagnose the consistency of the annual highest tide level and tidal range series, and the series that did not meet the consistency requirements were corrected.

[0066] A comparative analysis of long and short series parameters was employed to further analyze the representativeness of the sample series. Using a sliding window method, the mean and Cv values ​​were calculated at 5-year intervals for different sample lengths, such as 30 years, 35 years, 40 years, and up to the entire sample length. The changes in the estimated parameter values ​​with sample length were analyzed. If it was found that when the sample length reached a certain point, the parameter estimates no longer changed significantly with the sample length and reached stability, it indicated that the series was highly representative at the current sample length, and the series was deemed representative.

[0067] S2, Design Value Calculation: For a sample series that meets the requirements of consistency and representativeness, frequency curve fitting analysis is performed using the Pearson type 3 distribution function and the Günbel distribution function respectively. The parameters are estimated by combining the Bayesian method and the visual fitting method. The optimal frequency curve is selected, and the design high tide level, design high tide range, and design low tide range are calculated.

[0068] S3, Selection and breakdown of typical tide patterns: Select a long-duration typical tide pattern that includes the highest tide level from the measured tide pattern. According to the principle of "high tide level - long duration - high tide level later", select a "one rise and one fall" process located later in the whole tide pattern as the main tide pattern, and the rest as secondary tide patterns.

[0069] S4, Main Tide Pattern Design: The main tide pattern is designed by combining the design high tide level, design flood tide range, and design ebb tide range at the same frequency to obtain the design main tide pattern.

[0070] (1) The calculation method for the design tide level of the main tide type flood tide segment is as follows:

[0071] The corresponding high and low tide levels before the design high tide level are obtained by subtracting the design tidal range from the calculated design high tide level. The measured typical tidal level process corresponds to the tidal level of each time period during the flood tidal phase. Its high and low tide levels Subtract the values ​​to obtain the tidal range for each time period, and then divide by the total tidal range (high tide). Subtract high and low tides The proportion of tidal range in each period of the main tidal phase to the total tidal range is calculated. :

[0072]

[0073] Then, based on the calculated design tidal range, multiply it by the tidal range ratio of each time period in the main tidal pattern's tidal segment. And add high and low tide values To obtain the design tide level values ​​for each period of the main tide type's flood tide segment during the design tide level process. :

[0074]

[0075] (2) The calculation method for the design tide level of the ebb tide segment of the main tide type is as follows:

[0076] The corresponding low tide level is obtained by subtracting the design low tide range from the calculated design high tide level. The tide levels at various times during the ebb tide phase corresponding to the main tide pattern of a typical tidal process. rather than low tide Subtract the values ​​to obtain the tidal range for each time period, and divide by the total ebb tide range (high tide range). Subtract the low tide ( )), calculate the proportion of the tidal range of each period during the ebb tide of the main tide type to the total tidal range of the flood tide. ).

[0077]

[0078] Based on the calculated design ebb tide range, multiply by the calculated tidal range ratio for each time period of the ebb tide segment within the main tide pattern. And add the calculated low tide value. To obtain the design tide level values ​​for each time period during the ebb tide segment of the main tide pattern during the design tide level process. :

[0079]

[0080] S5, Secondary Tide Pattern Design: Based on the scaling ratio of the phase points corresponding to the primary tide pattern in the designed primary tide pattern process and the measured typical tide level process, the secondary tide pattern in the measured typical tide level process is scaled accordingly to obtain the designed secondary tide pattern process.

[0081] The second-tide design specifically includes:

[0082] Divide the design tide level at each phase point during the design of the main tide pattern by the measured tide level at the corresponding phase point during the measured typical tide level process, and calculate the scaling factor for different phase points of the main tide pattern. .

[0083] The scaling factor of the tide level at any phase point in the ebb tide segment of the secondary tide pattern is adopted using the scaling factor of the corresponding phase point in the ebb tide segment of the main tide pattern. The scaling factor of the tide level at any phase point in the ebb tide segment of the secondary tide pattern is adopted using the scaling factor of the corresponding phase point in the ebb tide segment of the main tide pattern. The design secondary tide pattern is obtained by calculating the following formula:

[0084]

[0085] The term "in-phase point" refers to a point that is in the same position relative to the start or end of the high tide. For example, a main tide type high tide segment has t periods from high tide to high tide, and the i-th period corresponds to a scaling factor; a secondary tide type high tide segment also has t periods from high tide to high tide, and the scaling factor of its i-th period is the same as that of the main tide type i-th period.

[0086] S6, splicing: splicing the design primary tidal pattern process with the design secondary tidal pattern process to obtain a complete long-duration design tidal level process.

[0087] Following the steps described above, the method of the present invention can calculate the design tide level process for any duration.

[0088] It should be further explained that the long duration mentioned in this invention usually refers to a tidal process with multiple tidal rise and fall cycles, which includes the highest tidal level and the changes in multiple tidal cycles before and after it.

[0089] To verify the superiority of the method of this invention, the 100-year return period design tide level process was calculated using both the method in the "Specification for Hydrological Calculation of Water Conservancy and Hydropower Projects" (SL / T278-2020) and the method of this invention. The comparison results are shown in Tables 1, 2, and 3:

[0090] Table 1. Comparison of the method of this invention with existing standard methods

[0091]

[0092] Table 2 Comparison of Design Tide Level Characteristics (Taking a 100-year return period as an example)

[0093]

[0094] Table 3 Comparison of design tide levels for multiple tidal cycles (taking a 100-year return period and a 3-day calendar as an example)

[0095]

[0096] As shown in the table above, existing standard methods can only provide a "one rise, one fall" design tide process, and the low tide level is derived from measured typical tide processes. The design maximum tide level remains fixed for different return periods. The design tide process curve is as follows: Figure 1 As shown in the figure. The method of this invention can derive a complete 3-day long-duration design tidal process. The main tidal pattern is jointly controlled by the design values ​​of tidal level and tidal range, while the secondary tidal pattern is controlled by the scaling ratio of the main tidal pattern. This method can calculate the design tidal process for any duration and any number of fluctuations. The design standard for the main tidal pattern is clear, the morphology of the secondary tidal pattern is consistent with the main tidal pattern, and the transitions between tidal cycles are smooth. It is significantly superior to existing methods in terms of physical rationality and engineering applicability. Its design tidal process line is shown in the figure. Figure 2 As shown.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features, and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for estimating long-duration designed tidal process lines, characterized in that, The method employs the same frequency for the main tide type and the corresponding frequency for the secondary tide type. The steps are as follows: S1, Data Preprocessing, including: Reliability analysis and consistency diagnosis of historical tide data are performed, and series that do not meet consistency requirements are corrected. The annual maximum value method was used to select the annual highest tide level for each year, forming an annual highest tide level sample series. Using the annual maximum value method and corresponding methods, the annual maximum tidal range, annual maximum ebb tidal range, corresponding tidal range, and corresponding ebb tidal range of each year are selected to form a tidal range sample series. Analyze the possibility of the annual highest tide level occurring simultaneously with various tidal ranges, and prioritize the sampling results from the annual maximum value method; The Mann-Kendall trend test and Pettt's jump test were used to diagnose the consistency of the annual highest tide level and tidal range series, and the series that did not meet the consistency requirements were reconstructed and corrected. Using a sliding window method, with a 5-year time interval, the mean and Cv values ​​were calculated for different sample lengths. When the parameter estimates tended to stabilize as the sample length increased, the series was deemed representative. S2, Design Calculation: For the sample series that meets the requirements of consistency and representativeness, frequency curve fitting analysis is performed using Pearson's three-type distribution function and Gumbel's distribution function respectively. The parameters are estimated by combining Bayesian method and visual fitting method. The frequency curve is selected optimally, and the design high tide level, design high tide range, and design low tide range are calculated. S3, Selection and breakdown of typical tidal patterns: Select a long-duration typical tidal process that includes the highest tide level from the measured tidal process. According to the principle of "high tide level - long duration - high tide level later", select a "one rise and one fall" process located later in the whole tidal process as the main tidal pattern, and the rest as secondary tidal patterns. S4, Main Tidal Pattern Design: The main tidal pattern is designed by combining the design high tide level, design flood tide range and design ebb tide range at the same frequency to obtain the design main tidal pattern process; S5, Secondary Tide Pattern Design: Based on the scaling ratio of the phase points corresponding to the primary tide pattern in the designed primary tide pattern process and the measured typical tide level process, the secondary tide pattern in the measured typical tide level process is scaled accordingly to obtain the designed secondary tide pattern process. S6, splicing: splicing the design primary tidal pattern process with the design secondary tidal pattern process to obtain a complete long-duration design tidal level process.

2. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S4, the calculation method for the design tide level of the main tide type flood tide segment is as follows: Determine the high and low tide values ​​before the design high tide level based on the design high tide level and the design tidal range. ; Calculate the proportion of the tidal range at each time period of the main tidal phase to the total tidal range. : In the formula, This is to measure the tide level values ​​at various times during the flood tide segment corresponding to the main tide pattern of a typical tidal process. Its high and low tide values, Its peak value; Calculate the design tide level values ​​for each period during the flood phase of the main tide pattern. for: In the formula, The high and low tide values ​​for the main tidal type during the high tide period. The high tide level of the main tidal type's high tide segment.

3. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S4, the calculation method for the design tide level of the ebb tide segment of the main tide type is as follows: The low-low tide value is determined based on the design high tide level and the design low tide range. ; Calculate the proportion of the tidal range during each period of the ebb tide phase to the total tidal range during the flood tide. : In the formula, The tide levels at various times during the ebb tide phase of the main tide type. The lowest low tide level during the ebb tide phase of the main tide pattern; Calculate the design tide level values ​​for each time period during the ebb tide phase of the main tide pattern. for: In the formula, This is the low tide level.

4. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S5, the secondary tide design specifically includes: Divide the design tide level at each phase point during the design of the main tide pattern by the measured tide level at the corresponding phase point during the measured typical tide level process, and calculate the scaling factor for different phase points of the main tide pattern. ; The scaling factor of the tide level at any phase point in the ebb tide segment of the secondary tide pattern is adopted using the scaling factor of the corresponding phase point in the ebb tide segment of the main tide pattern. The scaling factor of the tide level at any phase point in the ebb tide segment of the secondary tide pattern is adopted using the scaling factor of the corresponding phase point in the ebb tide segment of the main tide pattern. The design secondary tide pattern is obtained by calculating the following formula: In the formula, The design tide level value is for the secondary tide type. This refers to the measured tide level values ​​at the corresponding phase points of the secondary tide pattern during the actual measurement of typical tide levels.

5. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S3, the selection of the measured typical tide level process follows the principle of "high tide level - long duration - later high tide level"; where "high tide level" means that the highest tide level in the typical tide level process is close to the design high tide level, "long duration" means that the tide level changes slowly near the highest tide level and the high tide level lasts for a long time, and "later high tide level" means that the highest tide level occurs at a later position in the entire design tide level process.

6. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S4, the high and low tide values ​​and the low-low tide value of the main tide type flood tide segment and ebb tide segment are determined independently by the design high tide level, the design flood tide difference, and the design ebb tide difference, respectively. Among them, the high and low tide values ​​before the design high tide level are equal to the design high tide level minus the design flood tide difference, and the low-low tide value after the design high tide level are equal to the design high tide level minus the design ebb tide difference.

7. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that: In S6, the design of the main tide pattern is located in the later part of the entire design of the tide pattern.

8. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S6, the junction of the design primary tide pattern process and the design secondary tide pattern process is the starting point and the ending point of the design primary tide pattern process. The tide level value at the junction is directly adopted from the corresponding tide level value of the design primary tide pattern process to ensure the continuity of the junction point.

9. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, In S1, the corresponding method refers to selecting the tidal range of the highest annual tide level or the tidal range of the ebb tide.

10. The method for estimating a long-duration design tidal process line according to claim 1, characterized in that, S1 also includes ground settlement correction of historical tide data to ensure consistency between the reference datum and the zero point of the water gauge.

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