A river runoff restoration method and system

Abstract

The present invention discloses a method and system for restoring river runoff, and relates to the field of hydrology and water resources. The method comprises: determining the optimal adjacent natural river basin from a plurality of adjacent natural river basins of a target river basin; calculating the first change rate of the daily runoff ratio of the target river basin in a preset time period before and after the construction of the reservoir; calculating the second change rate of the daily runoff ratio of the optimal adjacent natural river basin in a preset time period before and after the construction of the reservoir; determining the daily runoff of each date in the preset monitoring time period after the target river basin restores the natural change characteristics according to the daily runoff of each date in the preset monitoring time period after the construction of the reservoir and the first change rate and the second change rate of the corresponding date; obtaining the daily runoff of each date after the restoration of the target river basin in the preset monitoring time period of each year according to the annual runoff change rate. The present invention can improve the accuracy of restoring the runoff regulated by the reservoir to the natural runoff.

Description

Technical Field

[0001] The invention relates to the field of hydrology and water resources, and in particular to a river runoff restoration method and system. Background Art

[0002] Natural runoff restoration is an important basis for water resource evaluation, reservoir scheduling, water use for ecological environment, and climate change research. The establishment of water conservancy projects such as reservoirs affects natural runoff and destroys the consistency of runoff sequences. The purpose of runoff restoration is to make runoff data reflect natural conditions.

[0003] At present, the commonly used methods for restoring natural runoff from reservoirs mainly include the water balance sub-item restoration method, the rainfall-runoff relationship method and the hydrological simulation method. The water balance method requires the collection of many data such as reservoir evaporation, leakage loss, surface rainfall, reservoir water level-storage capacity relationship, downstream water diversion, irrigation water consumption, etc. The calculation process is cumbersome, and the observation errors and statistical errors of various data will accumulate and amplify during the calculation process, resulting in greater uncertainty in the restoration results. Although the rainfall-runoff relationship method has a clear principle, it is limited by the integrity and reliability of historical meteorological data, and the rainfall-runoff relationship has significant temporal and spatial variability, making it difficult to ensure the accuracy of the restoration results. The hydrological simulation method requires a large amount of meteorological and topographic data, and then calibrates the parameters to realize the simulation of the hydrological process. Limited by the uncertainty of the data and the model itself, the workload required to use the model is very large. Although there are many runoff restoration methods that consider multiple data, in some river basins that are less affected by human activities and only affected by reservoir regulation and storage, and lack various data, the above restoration methods are difficult to implement or the effects are not good. Therefore, there is an urgent need for an improved natural runoff restoration method for reservoir regulation to achieve more efficient, simpler and more accurate daily runoff restoration. Summary of the invention

[0004] The purpose of the present invention is to provide a river runoff restoration method and system, which can improve the accuracy of restoring the runoff regulated by the reservoir to the natural runoff.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for river runoff restoration, comprising:

[0007] According to the target watershed that needs to be restored after reservoir regulation, determine the optimal adjacent natural watershed from multiple adjacent natural watersheds of the target watershed;

[0008] Calculate the change rate of the daily runoff ratio of the target watershed in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain a first change rate of the runoff ratio of the target watershed on each date in the preset date time period before the reservoir is built;

[0009] Calculate the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the reservoir is built and in the second preset time period after the reservoir is built, and obtain a second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built;

[0010] Determine the daily runoff of the target watershed on each date within the preset monitoring period after the reservoir is built, after eliminating the reservoir storage effect, according to the daily runoff of the target watershed on each date within the preset monitoring period after the reservoir is built and the first change rate of the corresponding date;

[0011] Determine the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff of each date in the target watershed after the reservoir is built and the second change rate of the corresponding date.

[0012] According to the annual runoff of the target basin in the preset monitoring period after the reservoir is built and the annual runoff of the target basin after the natural change characteristics are restored, the annual runoff change rate of the target basin in the preset monitoring period is obtained;

[0013] According to the annual runoff change rate and the daily runoff on each date within the preset monitoring time period after the natural change characteristics of the target watershed are restored, the daily runoff on each date of the target watershed after restoration within the preset monitoring time period of each year is obtained.

[0014] Optionally, the step of determining the optimal adjacent natural river basin from a plurality of adjacent natural river basins of the target river basin that needs to be restored after reservoir regulation specifically includes:

[0015] Calculate the correlation between the daily runoff of the target watershed during a preset observation period before the reservoir is built and the daily runoff of multiple adjacent natural watersheds of the target watershed during a preset observation period;

[0016] From the multiple adjacent natural watersheds, determine the candidate adjacent natural watershed with the highest correlation and the correlation being greater than or equal to a preset correlation threshold, and obtain the optimal adjacent natural watershed.

[0017] Optionally, the calculating the change rate of the daily runoff ratio of the target watershed in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, to obtain a first change rate of the runoff ratio of the target watershed on each date in the preset date time period before the reservoir is built, comprises:

[0018] Calculate the first daily runoff ratio of the target river basin on each date in the first preset date time period before the reservoir is built according to the daily average flow of each date in the target river basin in the first preset date time period before the reservoir is built and the multi-year daily average flow of the target river basin in the first preset date time period before the reservoir is built;

[0019] Calculate the second daily runoff ratio of the target basin on each date within the second preset date time period after the completion of the reservoir according to the daily average flow of the target basin on each date within the second preset date time period after the completion of the reservoir and the multi-year daily average flow of the target basin within the second preset date time period after the completion of the reservoir;

[0020] The first change rate is calculated according to the second daily runoff ratio and the first daily runoff ratio.

[0021] Optionally, the calculating the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the reservoir is built and in the second preset time period after the reservoir is built, to obtain a second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built, comprises:

[0022] Calculate the third daily runoff ratio of the optimal adjacent natural watershed on each date in the first preset time period before the construction of the reservoir according to the daily average flow of the optimal adjacent natural watershed on each date in the first preset time period before the construction of the reservoir and the multi-year daily average flow of the optimal adjacent natural watershed in the first preset time period before the construction of the reservoir;

[0023] Calculate the fourth daily runoff ratio of the optimal adjacent natural watershed on each date within the second preset date time period after the completion of the reservoir according to the daily average flow of the optimal adjacent natural watershed on each date within the second preset date time period after the completion of the reservoir and the multi-year daily average flow of the optimal adjacent natural watershed within the second preset date time period after the completion of the reservoir;

[0024] The second change rate is calculated according to the fourth daily runoff ratio and the third daily runoff ratio.

[0025] Optionally, before executing the step of "determining the daily runoff of the target river basin after eliminating the impact of reservoir storage during the preset monitoring time period after the reservoir is built according to the first change rate" and the step of "determining the annual runoff of the target river basin after restoring the natural change characteristics during the preset monitoring time period after the reservoir is built according to the daily runoff of the target river basin after eliminating the impact of reservoir storage during the preset monitoring time period after the reservoir is built and the second change rate", the method further includes:

[0026] Determine, according to the first change rate, a first runoff ratio change curve of the runoff ratio of the target watershed on each date within the preset date time period before the reservoir is built;

[0027] Determine, according to the second change rate, a second runoff ratio change curve of the runoff ratio of the optimal adjacent natural watershed on each date within the preset date time period before the reservoir is built;

[0028] Smoothing the first runoff ratio change curve and the second runoff ratio change curve to obtain a smoothed first runoff ratio change curve and a smoothed second runoff ratio change curve;

[0029] According to the smoothed first runoff ratio change curve, determine the runoff ratio change rate of the updated target watershed on each date within the preset date time period before the reservoir is built, and obtain an updated first change rate;

[0030] According to the smoothed second runoff ratio change curve, the runoff ratio change rate of the updated optimal adjacent natural watershed on each date within the preset date time period before the reservoir is built is determined to obtain an updated second change rate.

[0031] Optionally, the determining the daily runoff of the target watershed on each date after eliminating the impact of reservoir regulation within the preset monitoring period after the completion of the reservoir according to the daily runoff of the target watershed on each date within the preset monitoring period after the completion of the reservoir and the first change rate of the corresponding date, comprises:

[0032] According to the ratio of the daily runoff of the target river basin on each date within the preset monitoring time period after the completion of the reservoir and the first change rate of the corresponding date, the daily runoff of the target river basin on each date after eliminating the impact of reservoir regulation within the preset monitoring time period after the completion of the reservoir is determined.

[0033] Optionally, the daily runoff on each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff on each date in the preset monitoring period after the reservoir is built and the second change rate of the corresponding date after the reservoir regulation effect is eliminated in the target watershed, comprises:

[0034] Calculate the product of the daily runoff on each date in the preset monitoring period after the completion of the reservoir in the target watershed after eliminating the impact of reservoir storage and the second change rate of the corresponding date, and obtain the daily runoff on each date in the preset monitoring period after the target watershed restores the natural change characteristics.

[0035] Optionally, the annual runoff change rate of the target river basin in the preset monitoring time period is obtained according to the annual runoff of the target river basin in the preset monitoring time period after the reservoir is built and the annual runoff of the target river basin after the natural change characteristics are restored, including:

[0036] Calculate the ratio of the annual runoff of the target basin during the preset monitoring period after the reservoir is built to the annual runoff of the target basin after the natural change characteristics are restored, and obtain the annual runoff change rate of the target basin during the preset monitoring period.

[0037] Optionally, the daily runoff of each date in the preset monitoring time period after the target watershed restores the natural change characteristics according to the annual runoff change rate and the daily runoff of each date in the preset monitoring time period is obtained, and the daily runoff of each date in the target watershed after restoration in the preset monitoring time period each year includes:

[0038] The product of the annual runoff change rate and the daily runoff on each date within the preset monitoring time period after the target watershed restores the natural change characteristics is calculated to obtain the daily runoff on each date of the target watershed after restoration within the preset monitoring time period each year.

[0039] The present invention also provides a river runoff restoration system, which uses the above-mentioned river runoff restoration method, and the system comprises:

[0040] An optimal watershed determination module is used to determine an optimal adjacent natural watershed from a plurality of adjacent natural watersheds of the target watershed according to the target watershed that needs to be restored after reservoir regulation;

[0041] A first change rate calculation module is used to calculate the change rate of the daily runoff ratio of the target basin in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain a first change rate of the runoff ratio of the target basin on each date in the preset date time period before the reservoir is built;

[0042] A second change rate calculation module is used to calculate the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the reservoir is built and in the second preset time period after the reservoir is built, and obtain a second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built;

[0043] A first flow calculation module is used to determine the daily runoff of the target watershed on each date after eliminating the reservoir storage effect within the preset monitoring period after the reservoir is built, based on the daily runoff of the target watershed on each date within the preset monitoring period after the reservoir is built and the first change rate of the corresponding date;

[0044] A second flow calculation module is used to determine the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff of each date in the target watershed after the reservoir is built and the second change rate of the corresponding date.

[0045] An annual change rate calculation module is used to obtain the annual runoff change rate of the target basin within the preset monitoring period according to the annual runoff of the target basin within the preset monitoring period after the reservoir is built and the annual runoff of the target basin after the natural change characteristics are restored;

[0046] The runoff restoration module is used to obtain the daily runoff of each date in the target basin after restoration within the preset monitoring time period each year based on the annual runoff change rate and the daily runoff of each date in the preset monitoring time period after the natural change characteristics of the target basin are restored.

[0047] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0048] The invention discloses a river runoff restoration method and system, which comprises the following steps: determining an optimal adjacent natural river basin from a plurality of adjacent natural river basins of a target river basin; calculating a first change rate of the daily runoff ratio of the target river basin within a preset time period before and after the construction of a reservoir; calculating a second change rate of the daily runoff ratio of the optimal adjacent natural river basin within a preset time period before and after the construction of the reservoir; determining the daily runoff of each date within the preset monitoring time period after the target river basin restores the natural change characteristics according to the daily runoff of each date within the preset monitoring time period after the construction of the reservoir and the first change rate and the second change rate of the corresponding date; obtaining the daily runoff of each date after the restoration of the target river basin within the preset monitoring time period of each year according to the annual runoff change rate of each year. The invention effectively overcomes the problems of large data demand and complex calculation in the existing runoff restoration methods, and at the same time better considers the influence of the reservoir on the runoff, and can generate runoff restoration data on a daily scale, and has strong application prospects in areas affected by reservoirs and lacking data. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1A schematic flow chart of a river runoff restoration method provided in Example 1 of the present invention;

[0051] Figure 2 The ratio of the average runoff value of the basin where the reservoir is located and the adjacent basins before and after the reservoir is built to the multi-year average daily runoff in Example 1 of the present invention Curve graph; where Figure 2 Figure (a) shows the line graph of the first-day runoff ratio and the second-day runoff ratio of target basin A; Figure 2 Figure (b) is a line graph of the third-day runoff ratio and the fourth-day runoff ratio of the optimal adjacent basin B;

[0052] Figure 3 The watershed where the reservoir is located and the adjacent watershed in Example 1 of the present invention The curve after Fourier smoothing Curve graph; where Figure 3 Figure (a) is the first change rate line graph of the target basin A; Figure 3 Figure (b) is the second change rate line graph of the optimal adjacent basin B;

[0053] Figure 4 for Line graph of annual runoff change rate;

[0054] Figure 5 for Schematic diagram of the comparison of the daily runoff sequence before and after the restoration of the segment. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The purpose of the present invention is to provide a river runoff restoration method and system, aiming to improve the accuracy of restoring the runoff after reservoir regulation to natural runoff.

[0057] The present invention restores the runoff after reservoir regulation to natural runoff, which belongs to the reconstruction of river runoff regulated by reservoir based on adjacent natural river basins, especially the restoration of river runoff regulated by reservoir based on adjacent natural river basins.

[0058] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Example 1

[0059] like Figure 1 As shown, the river runoff restoration method in this embodiment includes:

[0060] Step S1: According to the target watershed that needs to be restored after reservoir regulation, the optimal adjacent natural watershed is determined from the adjacent natural watersheds of the target watershed.

[0061] S1 specifically includes:

[0062] Step S11: Calculate the correlation between the daily runoff of the target basin during a preset observation period before the reservoir is built and the daily runoff of multiple adjacent natural basins of the target basin during a preset observation period.

[0063] Step S12: From a plurality of adjacent natural watersheds, determine a candidate adjacent natural watershed with the highest correlation and a correlation greater than or equal to a preset correlation threshold, and obtain the optimal adjacent natural watershed.

[0064] In practical applications, the optimal adjacent natural basin B is determined based on the Pearson correlation coefficient of daily runoff between the target basin A that needs to be restored after reservoir regulation and multiple adjacent natural basins before reservoir construction.

[0065] For the daily runoff observation data of the target basin A and the candidate adjacent basins that need to be restored due to the construction of the reservoir, the candidate adjacent basins are natural basins that are not affected by human activities, that is, adjacent natural basins. The runoff sequence is divided into two time periods according to the time of reservoir construction (before the reservoir is built, section I; after the reservoir is built, section II), and the Pearson correlation coefficient of the runoff of the two basins before the reservoir is built is calculated. The basin with the largest correlation coefficient and greater than or equal to 0.8 is taken as the "adjacent basin" for subsequent restoration steps, where the preset correlation threshold can be set to 0.8.

[0066] The Pearson correlation coefficient can better reflect the linear correlation degree of daily runoff changes in two basins. The calculation method is shown in formula (1).

[0067] (1)

[0068] in, is the Pearson linear correlation coefficient between basins A and B, is the number of observation days, Basin A The daily runoff, It is the Bth The daily runoff, is the average daily runoff of Basin A, is the average daily runoff value of Basin B.

[0069] Step S2: Calculate the change rate of the daily runoff ratio of the target basin in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain the first change rate of the runoff ratio of the target basin on each date in the preset date time period before the reservoir is built.

[0070] S2 specifically includes:

[0071] Step S21: Calculate the first daily runoff ratio of each date in the first preset date time period before the construction of the reservoir in the target basin based on the daily average flow of each date in the first preset date time period before the construction of the reservoir in the target basin and the multi-year daily average flow of the target basin in the first preset date time period before the construction of the reservoir.

[0072] In practical applications, the ratio of the average daily runoff of the target basin in the two periods before and after the completion of the reservoir to the average daily runoff of the corresponding period over many years is calculated. .

[0073] The calculation method of is shown in formula (2).

[0074] (2)

[0075] in, is the day number ( =1,2,…,366), It represents the average daily runoff, which is equal to the sum of the daily runoff from 1 to 366 in each period divided by the number of years. It represents the arithmetic mean of daily runoff over a period of time, that is, the sum of daily runoff in all years divided by the total number of days.

[0076] For example, the day number 1 to 366 represents the day number in a year. Take 2000 to 2003 as an example to calculate the day number. The average value is 1 , is equivalent to calculating the average of the runoff data on the first day of 2000, 2001, 2002, and 2003. It means the As for the leap year from 1 to 366, let's take 2000 to 2003 as an example. In these four years, 2000 is a leap year, and the only extra day in a leap year is February 29, which is numbered 60. So the average value of number 60 is It is only equal to the value of the 60th day of the leap year 2000. The average value of the ordinal number 61 is equal to the average value of the 61st day (March 1) of 2000, 2001, 2002, and 2003.

[0077] Calculate the ratio of the average daily runoff of the target basin A in the preset time period before the reservoir construction (I period) to the average daily runoff of the corresponding period over many years .

[0078] Step S22: Calculate the second daily runoff ratio of the target basin on each date within the second preset time period after the completion of the reservoir based on the daily average flow of each date within the second preset time period after the completion of the reservoir and the multi-year daily average flow of the target basin within the second preset time period after the completion of the reservoir.

[0079] In practical applications, the ratio of the average daily runoff of the target basin A in the preset time period after the reservoir construction (Section II) to the average daily runoff of the corresponding period over many years is calculated. .

[0080] Step S23: Calculate the initial first change rate according to the second daily runoff ratio and the first daily runoff ratio.

[0081] In practical applications, the value of the target basin A reservoir before and after its completion is calculated according to formula (3). ratio , the target basin Denoted as , The calculation method of is shown in formula (3).

[0082] (3)

[0083] in, is the day number ( =1,2,…,366), Indicates The target basin and adjacent basins after and before the completion of the reservoir ratio, and Respectively represent a certain basin I, Section Heaven value.

[0084] Step S24: To reduce The fluctuation of the curve is analyzed by Fourier smoothing method. Perform smoothing to obtain the final first rate of change .

[0085] Step S3: Calculate the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the construction of the reservoir and in the second preset time period after the construction of the reservoir, and obtain the second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the construction of the reservoir.

[0086] S3 specifically includes:

[0087] Step S31: Calculate the third daily runoff ratio of the best adjacent natural watershed on each date within the first preset time period before the construction of the reservoir based on the average daily flow of the best adjacent natural watershed on each date within the first preset time period before the construction of the reservoir and the multi-year average daily flow of the best adjacent natural watershed within the first preset time period before the construction of the reservoir.

[0088] In practical applications, formula (2) is used to calculate the ratio of the average daily runoff of the adjacent basin in the two periods before and after the construction of the reservoir to the multi-year average daily runoff in the corresponding period. .

[0089] Calculate the ratio of the average daily runoff of the optimal adjacent natural watershed B in the preset time period before the reservoir construction (I period) to the average daily runoff of the corresponding period over many years .

[0090] Step S32: Calculate the fourth daily runoff ratio of the best adjacent natural watershed on each date within the second preset time period after the construction of the reservoir based on the average daily flow of the best adjacent natural watershed on each date within the second preset time period after the construction of the reservoir and the multi-year average daily flow of the best adjacent natural watershed within the second preset time period after the construction of the reservoir.

[0091] In practical applications, the ratio of the average daily runoff of the optimal adjacent natural watershed B in the preset time period after the reservoir construction (Section II) to the multi-year average daily runoff of the corresponding period is calculated. .

[0092] Step S33: Calculate the second change rate according to the fourth daily runoff ratio and the third daily runoff ratio.

[0093] In practical applications, the relationship between the adjacent basin B reservoir after and before its completion is calculated according to formula (3). ratio , adjacent to the basin remember .

[0094] Step S34: Use Fourier smoothing method to Smoothing is performed to obtain the final second rate of change .

[0095] As a specific implementation, before executing step S4 and step S5, the method further includes the following steps:

[0096] Step 001: Determine a first runoff ratio variation curve of the runoff ratio of a target watershed on each date within a preset date period before the completion of a reservoir according to a first variation rate.

[0097] Step 002: According to the second change rate, determine a second runoff ratio change curve of the runoff ratio of the optimal adjacent natural watershed on each date within a preset date time period before the reservoir is built.

[0098] Step 003: Smoothing the first runoff ratio change curve and the second runoff ratio change curve to obtain a smoothed first runoff ratio change curve and a smoothed second runoff ratio change curve.

[0099] Step 004: According to the smoothed first runoff ratio change curve, determine the runoff ratio change rate of the updated target basin on each date within a preset date time period before the reservoir is built, and obtain the updated first change rate.

[0100] Step 005: According to the smoothed second runoff ratio change curve, determine the runoff ratio change rate of the updated optimal adjacent natural watershed on each date within a preset date time period before the reservoir is built, and obtain an updated second change rate.

[0101] In practical applications, the daily flow of target basin A and adjacent basin B is calculated. value, get their respective curve. There are large fluctuations during the year. In order to reduce the fluctuations while retaining the effective trend, stable change characteristics are extracted. Fourier smoothing is a method to remove high-frequency noise by retaining low-frequency components. This method uses Fourier transform to convert the signal to the frequency domain, smoothes the sequence by removing high-frequency components in the frequency domain, and then converts the signal back to the time domain through inverse Fourier transform.

[0102] For the year The curves are smoothed using Fourier transform, and the obtained curves are recorded as and .

[0103] Step S4: Determine the daily runoff of the target basin on each date after eliminating the impact of reservoir regulation within the preset monitoring period after the reservoir is built, based on the daily runoff of the target basin on each date within the preset monitoring period after the reservoir is built and the first change rate of the corresponding date.

[0104] Specifically, based on the ratio of the daily runoff of the target river basin on each date within the preset monitoring period after the completion of the reservoir and the first change rate of the corresponding date, the daily runoff of the target river basin on each date after eliminating the impact of reservoir regulation within the preset monitoring period after the completion of the reservoir is determined.

[0105] In practical applications, the daily runoff value in the measured daily runoff series of Section II is divided by the corresponding day of the year. To eliminate the impact of reservoir regulation, the calculation method is shown in formula (4).

[0106] (4)

[0107] in, for Segment runoff sequence number ( =1,2,… (length of daily runoff sequence in the segment) for The corresponding day number ( =1,2,…,366), express The original daily runoff series, For the target basin A curve, Represents the daily runoff sequence after eliminating the impact of reservoir regulation.

[0108] Step S5: Determine the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics based on the daily runoff of each date in the preset monitoring period after the reservoir is built and the second change rate of the corresponding date.

[0109] Specifically, the product of the daily runoff on each date in the target watershed after eliminating the impact of reservoir regulation within the preset monitoring period after the completion of the reservoir and the second change rate of the corresponding date is calculated to obtain the daily runoff on each date in the preset monitoring period after the target watershed restores the natural change characteristics.

[0110] Multiply the daily runoff value in the daily runoff sequence obtained in step S4 by the corresponding day number in the year. To restore the natural variation characteristics of the target watershed, the calculation method is shown in formula (5).

[0111] (5)

[0112] in, For adjacent basins curve, Represents the daily runoff sequence after restoring the natural variation characteristics of the target watershed.

[0113] What is the day number corresponding to each value of the runoff sequence in a year? For example, the runoff value on January 1, 2000 is 50, and the day number corresponding to January 1 in a year is 1. Then multiply the runoff value 50 by the day number corresponding to 1. .like Figure 2 and Figure 3 As shown, , and It is 1~366, and each day number corresponds to a value.

[0114] Step S6: According to the annual runoff of the target basin in the preset monitoring period after the reservoir is built and the annual runoff of the target basin after restoring the natural change characteristics, the annual runoff change rate of the target basin in the preset monitoring period is obtained.

[0115] Specifically, the ratio of the annual runoff of the target basin during the preset monitoring period after the reservoir is built to the annual runoff of the target basin after the natural change characteristics are restored is calculated to obtain the annual runoff change rate of the target basin during the preset monitoring period.

[0116] In practical applications, the present invention targets annual regulation reservoirs, does not consider water loss such as reservoir evaporation, and assumes that the total annual water volume of outflow is the same as the total annual water volume of inflow. Calculate the ratio of the annual runoff of the original daily runoff sequence of the A basin in section II to the annual runoff of the daily runoff sequence obtained in step S5. , the calculation method is shown in formula (6).

[0117] (6)

[0118] in, for The number of years in the segment, for Section years value, The original daily runoff sequence of Basin A is The annual runoff of each year in the segment is represents the daily runoff sequence obtained in step S5 The annual runoff in each year of the segment is means For example, if we have daily runoff data from 2000 to 2002, there are 366 days in 2000, 365 days in 2001, and 365 days in 2002. The value of is 1, 2, 3, ..., 1096 (based on 366+365+365=1096). According to the daily runoff data sequence , we can get the annual runoff of each year, which is equal to the sum of the daily runoff in each year. For example, the annual runoff in 2000 is equal to the sum of the runoff of each day in 2000. Annual runoff in each year and .

[0119] Step S7: According to the annual runoff change rate and the daily runoff of each date in the preset monitoring time period after the natural change characteristics of the target basin are restored, the daily runoff of each date in the target basin after restoration in the preset monitoring time period each year is obtained.

[0120] Specifically, the product of the annual runoff change rate and the daily runoff on each date within the preset monitoring period after the natural change characteristics of the target basin are restored is calculated to obtain the daily runoff on each date after the target basin is restored within the preset monitoring period each year.

[0121] In practical applications, the daily runoff value of each year in the daily runoff sequence obtained in step S6 is multiplied by the corresponding year. , and obtain the final restored natural runoff sequence.

[0122] (7)

[0123] in, for The number of years in the segment, for Section years value, This is the natural runoff sequence after final restoration.

[0124] Now take the daily runoff data of a basin A from 1962 to 2022 as an example, where 1962-2001 is the natural runoff without a reservoir, and the runoff data from 2002 to 2022 is the runoff out of the reservoir. Basin B, Basin C and Basin D are adjacent basins of A, and have daily runoff data of Basin A, Basin B, Basin C and Basin D from 1962 to 2022; according to the method of the present invention, the runoff restoration process of the region is:

[0125] (1) The Pearson correlation coefficient of runoff between basins A and B, C, and D before the construction of reservoirs (1962-2001) was calculated. The correlation coefficients were 0.933, 0.9, and 0.7. The correlation between basin B and A was the largest and greater than 0.8. Therefore, basin B was selected as the adjacent basin of basin A for the subsequent restoration steps.

[0126] (2) If Figure 2 As shown, the calculations for 1962-2001 are and 2002-2022 The multi-year average daily runoff and the average daily runoff of basin A and adjacent basin B in the two time periods are calculated, and the ratio of the average runoff of basins A and B in the two time periods to the multi-year average daily runoff is calculated according to formula (1): . Figure 2 Figure (a) is a line chart showing the ratio of the first and second daily runoffs in the target basin A. Figure 2 Figure (b) is a line graph of the third and fourth daily runoff ratios of the optimal adjacent basin B.

[0127] (3) According to formula (2), the target basin A and the adjacent basin B are calculated after and before the completion of the reservoir. ratio and .

[0128] (4) If Figure 3 As shown, the Fourier transform of the above steps is used The curves after smoothing are: and . Figure 3 Figure (a) is the first change rate line graph of the target basin A; Figure 3 Figure (b) is the second change rate line graph of the optimal adjacent watershed B.

[0129] (5) According to formula (3), the original daily runoff series of basin A from 2002 to 2022 corresponds to the date of the year. To eliminate the impact of reservoir regulation.

[0130] (6) Multiply the daily runoff value in the daily runoff sequence obtained in step (5) by the corresponding date in the year. To restore the natural variation characteristics of the target watershed and obtain the daily runoff sequence .

[0131] (7) Calculate the original daily runoff series and The ratio of annual runoff in each year .

[0132] (8) Figure 4 for Line graph of annual runoff change rate; Figure 4 As shown, The daily runoff in each year is multiplied by the corresponding year The final restored daily-scale natural runoff sequence is obtained. Figure 5 for Schematic diagram of the comparison of the daily runoff sequence before and after the restoration of the segment.

[0133] The runoff restoration method provided by the present invention can eliminate the impact of the reservoir on the runoff, and obtain the restored runoff sequence. The restored natural runoff sequence can be used to analyze the impact of climate change on runoff, water resource utilization management, and reservoir operation scheduling. When it is difficult to use other restoration methods due to reservoir regulation and lack of other data such as reservoir evaporation, reservoir leakage, reservoir water level, storage capacity curve, irrigation, etc., and when daily runoff restoration data is required, the present invention can better achieve runoff restoration. Therefore, in the above-mentioned areas, the present invention has a strong application prospect.

[0134] Example 2

[0135] Based on Example 1, the present invention further provides a river runoff restoration system, the system comprising:

[0136] The optimal watershed determination module is used to determine the optimal adjacent natural watershed from multiple adjacent natural watersheds of the target watershed according to the target watershed that needs to be restored after reservoir regulation;

[0137] A first change rate calculation module is used to calculate the change rate of the daily runoff ratio of the target basin in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain a first change rate of the runoff ratio of the target basin on each date in the preset date time period before the reservoir is built;

[0138] A second change rate calculation module is used to calculate the change rate of the daily runoff ratio of the optimal adjacent natural watershed in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain a second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built;

[0139] A first flow calculation module is used to determine the daily runoff of the target basin on each date after eliminating the reservoir regulation effect within the preset monitoring period after the reservoir is built, based on the daily runoff of the target basin on each date within the preset monitoring period after the reservoir is built and the first change rate of the corresponding date;

[0140] The second flow calculation module is used to determine the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff of each date after the target watershed eliminates the impact of reservoir regulation and storage in the preset monitoring period after the reservoir is built and the second change rate of the corresponding date;

[0141] The annual change rate calculation module is used to obtain the annual runoff change rate of the target basin in the preset monitoring period according to the annual runoff of the target basin in the preset monitoring period after the reservoir is built and the annual runoff of the target basin after the natural change characteristics are restored;

[0142] The runoff restoration module is used to obtain the daily runoff of each date in the preset monitoring period after the target basin is restored to its natural change characteristics based on the annual runoff change rate and the daily runoff of each date in the preset monitoring period each year.

[0143] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0144] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for river runoff restoration, characterized in that: The method comprises: According to the target watershed that needs to be restored after reservoir regulation, determine the optimal adjacent natural watershed from multiple adjacent natural watersheds of the target watershed; Calculate the change rate of the daily runoff ratio of the target watershed in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain a first change rate of the runoff ratio of the target watershed on each date in the preset date time period before the reservoir is built; Calculate the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the reservoir is built and in the second preset time period after the reservoir is built, and obtain a second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built; Determine the daily runoff of the target watershed on each date within the preset monitoring period after the reservoir is built, after eliminating the reservoir regulation effect, based on the daily runoff of the target watershed on each date within the preset monitoring period after the reservoir is built and the first change rate of the corresponding date; Determine the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff of each date in the target watershed after the reservoir is built and the second change rate of the corresponding date. According to the annual runoff of the target basin in the preset monitoring period after the reservoir is built and the annual runoff of the target basin after the natural change characteristics are restored, the annual runoff change rate of the target basin in the preset monitoring period is obtained; According to the annual runoff change rate and the daily runoff on each date within the preset monitoring time period after the natural change characteristics of the target watershed are restored, the daily runoff on each date of the target watershed after restoration within the preset monitoring time period of each year is obtained.

2. The method for river runoff restoration according to claim 1, characterized in that: The method of determining the optimal adjacent natural river basin from a plurality of adjacent natural river basins of the target river basin according to the target river basin that needs to be restored after reservoir regulation specifically includes: Calculate the correlation between the daily runoff of the target river basin during a preset observation period before the reservoir is built and the daily runoff of multiple adjacent natural river basins of the target river basin during a preset observation period; From the multiple adjacent natural watersheds, determine the candidate adjacent natural watershed with the highest correlation and the correlation being greater than or equal to a preset correlation threshold, and obtain the optimal adjacent natural watershed.

3. The method for river runoff restoration according to claim 1, characterized in that: The step of calculating the change rate of the daily runoff ratio of the target watershed in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtaining a first change rate of the runoff ratio of the target watershed on each date in the preset date time period before the reservoir is built, comprises: Calculate the first daily runoff ratio of the target river basin on each date in the first preset date time period before the reservoir is built according to the daily average flow of each date in the first preset date time period before the reservoir is built and the multi-year daily average flow of the target river basin in the first preset date time period before the reservoir is built; Calculate the second daily runoff ratio of the target basin on each date within the second preset date time period after the completion of the reservoir according to the daily average flow of the target basin on each date within the second preset date time period after the completion of the reservoir and the multi-year daily average flow of the target basin within the second preset date time period after the completion of the reservoir; The first change rate is calculated according to the second daily runoff ratio and the first daily runoff ratio.

4. The method for river runoff restoration according to claim 1, characterized in that: The step of calculating the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the reservoir is built and in the second preset time period after the reservoir is built, and obtaining the second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built, comprises: Calculate the third daily runoff ratio of the optimal adjacent natural watershed on each date in the first preset time period before the construction of the reservoir according to the daily average flow of the optimal adjacent natural watershed on each date in the first preset time period before the construction of the reservoir and the multi-year daily average flow of the optimal adjacent natural watershed in the first preset time period before the construction of the reservoir; Calculate the fourth daily runoff ratio of the optimal adjacent natural watershed on each date within the second preset date time period after the completion of the reservoir according to the daily average flow of the optimal adjacent natural watershed on each date within the second preset date time period after the completion of the reservoir and the multi-year daily average flow of the optimal adjacent natural watershed within the second preset date time period after the completion of the reservoir; The second change rate is calculated according to the fourth daily runoff ratio and the third daily runoff ratio.

5. The method for river runoff restoration according to claim 1, characterized in that: Before executing the step "determining the daily runoff of the target basin after eliminating the reservoir storage effect within the preset monitoring period after the reservoir is built according to the first change rate" and the step "determining the annual runoff of the target basin after restoring the natural change characteristics within the preset monitoring period after the reservoir is built according to the daily runoff of the target basin after eliminating the reservoir storage effect within the preset monitoring period after the reservoir is built and the second change rate", the method further includes: Determine, according to the first change rate, a first runoff ratio change curve of the runoff ratio of the target watershed on each date within the preset date time period before the reservoir is built; Determine, according to the second change rate, a second runoff ratio change curve of the runoff ratio of the optimal adjacent natural watershed on each date within the preset date time period before the reservoir is built; Smoothing the first runoff ratio change curve and the second runoff ratio change curve to obtain a smoothed first runoff ratio change curve and a smoothed second runoff ratio change curve; According to the smoothed first runoff ratio change curve, determine the runoff ratio change rate of the updated target watershed on each date within the preset date time period before the reservoir is built, and obtain an updated first change rate; According to the smoothed second runoff ratio change curve, the runoff ratio change rate of the updated optimal adjacent natural watershed on each date within the preset date time period before the reservoir is built is determined to obtain an updated second change rate.

6. The method for river runoff restoration according to claim 1, characterized in that: The step of determining the daily runoff of the target watershed on each date after eliminating the impact of reservoir regulation within the preset monitoring period after the completion of the reservoir based on the daily runoff of the target watershed on each date within the preset monitoring period after the completion of the reservoir and the first change rate of the corresponding date comprises: According to the ratio of the daily runoff of the target river basin on each date within the preset monitoring time period after the completion of the reservoir and the first change rate of the corresponding date, the daily runoff of the target river basin on each date after eliminating the impact of reservoir regulation within the preset monitoring time period after the completion of the reservoir is determined.

7. The method for river runoff restoration according to claim 1, characterized in that: The method of determining the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff of each date in the target watershed after the reservoir is built and the second change rate of the corresponding date after the reservoir regulation effect is eliminated in the preset monitoring period includes: Calculate the product of the daily runoff on each date in the preset monitoring period after the completion of the reservoir in the target watershed after eliminating the impact of reservoir storage and the second change rate of the corresponding date, and obtain the daily runoff on each date in the preset monitoring period after the target watershed restores the natural change characteristics.

8. The method for river runoff restoration according to claim 1, characterized in that: The annual runoff change rate of the target basin in the preset monitoring period is obtained according to the annual runoff of the target basin in the preset monitoring period after the reservoir is built and the annual runoff of the target basin after the natural change characteristics are restored, including: Calculate the ratio of the annual runoff of the target basin during the preset monitoring period after the reservoir is built to the annual runoff of the target basin after the natural change characteristics are restored, and obtain the annual runoff change rate of the target basin during the preset monitoring period.

9. The method for river runoff restoration according to claim 1, characterized in that: The method of obtaining the daily runoff of each date after restoration of the target watershed within the preset monitoring time period according to the annual runoff change rate and the daily runoff of each date within the preset monitoring time period after the natural change characteristics of the target watershed are restored includes: The product of the annual runoff change rate and the daily runoff on each date within the preset monitoring time period after the target watershed restores the natural change characteristics is calculated to obtain the daily runoff on each date of the target watershed after restoration within the preset monitoring time period each year.

10. A river runoff restoration system, characterized in that: The system comprises: An optimal watershed determination module is used to determine an optimal adjacent natural watershed from a plurality of adjacent natural watersheds of the target watershed according to the target watershed that needs to be restored after reservoir regulation; A first change rate calculation module is used to calculate the change rate of the daily runoff ratio of the target basin in a first preset time period before the reservoir is built and in a second preset time period after the reservoir is built, and obtain a first change rate of the runoff ratio of the target basin on each date in the preset date time period before the reservoir is built; A second change rate calculation module is used to calculate the change rate of the daily runoff ratio of the optimal adjacent natural watershed in the first preset time period before the reservoir is built and in the second preset time period after the reservoir is built, and obtain a second change rate of the runoff ratio of the optimal adjacent natural watershed on each date in the preset date time period before the reservoir is built; A first flow calculation module is used to determine the daily runoff of the target watershed on each date after eliminating the reservoir storage effect within the preset monitoring period after the reservoir is built, based on the daily runoff of the target watershed on each date within the preset monitoring period after the reservoir is built and the first change rate of the corresponding date; A second flow calculation module is used to determine the daily runoff of each date in the preset monitoring period after the target watershed restores the natural change characteristics according to the daily runoff of each date in the target watershed after the reservoir is built and the second change rate of the corresponding date. An annual change rate calculation module is used to obtain the annual runoff change rate of the target basin within the preset monitoring period according to the annual runoff of the target basin within the preset monitoring period after the reservoir is built and the annual runoff of the target basin after the natural change characteristics are restored; The runoff restoration module is used to obtain the daily runoff of each date in the target basin after restoration within the preset monitoring time period each year based on the annual runoff change rate and the daily runoff of each date in the preset monitoring time period after the natural change characteristics of the target basin are restored.

Images