Drainage basin water and sediment trend change analysis method and system and medium

Abstract

The invention relates to a drainage basin water and sediment trend change analysis method and system and a medium. The method comprises the steps that the continuous accumulated value of drainage basin runoff and sediment transport along with time in the same time period is calculated; drawing a double accumulation curve by taking the runoff volume and sediment transport accumulation value as a horizontal axis and a longitudinal axis respectively; linear regression is established by combining the extreme value of the drainage basin water and sediment accumulation value, and then the drainage basin water and sediment trend change characteristics in the sample space are judged based on deviation distribution of a water and sediment accumulation value sample and a regression curve; calculating the sample deviation of the water and sediment accumulated value; calculating a deviation sequence corresponding to the sediment transport accumulated value; defining a scale scaling factor to homogenize the deviation sequence; and selecting a double-accumulation curve mutation point, and finishing basin water and sediment trend change analysis. According to the method, a traditional double-accumulation curve method is improved, nonlinear changes, abrupt change points and trend turning points in the water-sediment relation can be recognized more accurately, and therefore the accuracy and reliability of an analysis result are improved.

Description

Technical Field

[0001] This application relates to the field of hydrology and water resources, and particularly to a method, system, and medium for analyzing the trend change of water and sediment in a basin. Background Art

[0002] The double mass curve method is a main means to test the trend change between hydrological elements in a basin, and has been widely used in the consistency test of water and sediment changes, missing value interpolation, data correction, and attribution analysis of trend changes. The double mass curve method calculates the continuous cumulative values of the basin runoff and sediment transport volume over the same period of time, and plots the scatter diagram of the double cumulative values in a rectangular coordinate system. By observing whether the slope of the linear growth relationship of the double cumulative values in the figure changes, it is judged whether the water and sediment trend in the basin has changed. Using the double mass curve method can not only reveal whether the water and sediment relationship in the basin has a trend change, but also determine the abrupt change point of the water and sediment trend according to the change of the cumulative value slope. At the same time, since the continuous cumulative value of the basin water and sediment represents the continuous water and sediment process in the basin for many years, the double mass curve method can weaken the influence of the volatility and randomness of water and sediment changes on the judgment of the overall water and sediment trend. According to the abrupt change point of the double mass curve, the water and sediment trend in the basin is divided into stages. Before the abrupt change point is the natural reference period of the water and sediment trend change, and after the abrupt change point is the response period of the water and sediment trend change. By extending the linear relationship of the basin water and sediment cumulative values in the natural reference period and calculating the difference between the water and sediment cumulative values in the response period and the reference period, the attribution analysis of the water and sediment trend change in the basin is carried out.

[0003] The application conditions of the double mass curve are relatively strict, the accuracy of the double mass curve method is not high, and it is greatly affected by the volatility of the water and sediment process. The selection of the abrupt change point of the double mass curve depends very much on subjective judgment and engineering experience, and there is a lack of mathematical proof for the selection of the abrupt change point. It is necessary to consider the influence of climate change and human activities (soil and water conservation measures, reservoir projects) in the study area on the water and sediment trend change. Summary of the Invention

[0004] The purpose of the embodiments of this application is to overcome the deficiencies of the prior art, and provide a method, system, and medium for analyzing the trend change of water and sediment in a basin. By improving the traditional double mass curve method, the non-linear changes, abrupt change points, and trend turning points in the water and sediment relationship can be more accurately identified, thereby improving the accuracy and reliability of the analysis results.

[0005] To achieve the above purpose, this application provides the following technical solutions:

[0006] In the first aspect, the embodiments of this application provide a method for analyzing the trend change of water and sediment in a basin, including the following steps:

[0007] Calculate the continuous cumulative values of the basin runoff and sediment transport volume over the same period of time with respect to time;

[0008] Taking the cumulative values of runoff and sediment transport as the horizontal and vertical axes respectively, a double cumulative curve is plotted;

[0009] Combined with the extreme values of the cumulative water and sediment values in the basin, a linear regression is established, and then based on the deviation distribution between the cumulative water and sediment value samples and the regression curve, the characteristics of the trend change of water and sediment in the basin within the sample space are judged;

[0010] Calculate the sample deviation of the cumulative water and sediment values;

[0011] Calculate the deviation sequence corresponding to the cumulative sediment transport value;

[0012] According to the absolute value of the deviation between the cumulative value and the regression curve, a scale scaling factor is defined to homogenize the deviation sequence;

[0013] Select the mutation points of the double cumulative curve to complete the analysis of the trend change of water and sediment in the basin.

[0014] The specific calculation of the continuous cumulative values of the runoff and sediment transport in the basin over the same period is as follows,

[0015]

[0016] Q’ is the continuous cumulative value of the runoff in the basin, Qi is the runoff in the basin in the i-th year of the statistical sequence, n is the number of samples in the statistical sequence, S’ is the continuous cumulative value of the sediment transport in the basin, and Si is the sediment transport in the basin in the i-th year of the statistical sequence.

[0017] The specific process of combining the extreme values of the cumulative water and sediment values in the basin to establish a linear regression, and then judging the characteristics of the trend change of water and sediment in the basin within the sample space based on the deviation distribution between the cumulative water and sediment value samples and the regression curve is as follows,

[0018] Since the continuous cumulative values of water and sediment are both monotonically increasing sequences, and the maximum and minimum values correspond to the two ends of the sequence respectively, the linear regression expression of the cumulative water and sediment values in the basin is:

[0019] S' i =a0Q' i +S'1 (3)

[0020]

[0021] S’ i and Q’ i correspond to the i-th values in the cumulative sediment transport and runoff value sequences respectively, a0 is the slope of the linear regression, S’1 is the initial value of the cumulative sediment transport value, n is the number of samples in the basin water and sediment sequence, Q’1 is the initial value of the cumulative runoff value, S’ n is the end value of the cumulative sediment transport value, and Q’ n is the end value of the cumulative runoff value.

[0022] The sample deviation of the calculated cumulative water and sediment values is specifically

[0023] λ i = S' i - S'1 - a0Q' i (5)

[0024] λ i is the deviation of the cumulative sediment transport value of the i-th one from the linear regression of the extreme value.

[0025] The deviation sequence corresponding to the calculated cumulative sediment transport value is specifically

[0026] λ = {λ1, λ2... λ n} (6)

[0027] λ is the deviation sequence corresponding to the annual cumulative water and sediment values.

[0028] The specific method of homogenizing the deviation sequence by defining a scale factor according to the absolute value of the deviation between the cumulative value and the regression curve is

[0029] λ' i = λ i · η i (7)

[0030]

[0031] λ i ’ is the homogenized value corresponding to the i-th deviation, and η i is the scale factor corresponding to the deviation λ i

[0032] When the deviation is less than 0, the scale factor has a positive correlation with the deviation magnitude; when the deviation is equal to 0, the scale factor is also 0; when the deviation is greater than 0, the scale factor has a negative correlation with the deviation magnitude. Therefore, the greater the deviation of the cumulative value from the extreme regression curve, the smaller the scale factor. By scaling the extreme outliers, the homogenized deviation sequence can effectively reduce the impact of water and sediment fluctuations on trend judgment, and the standardized deviation sequence is calculated using (7).

[0033] λ' = {λ1', λ2'... λ n '} (9)

[0034] ​Let λ’ be the homogenized deviation sequence corresponding to the annual cumulative water and sediment values. The statistical t-test method is used to determine whether there is a significant difference between the homogenized deviation sequence and the normal distribution centered at 0. When the test value P obtained from the t-test is greater than 0.05, it indicates that there is no significant difference between the distribution center of the standardized deviation sequence and 0, and the deviation is distributed within the finite boundaries on both sides of 0. The linear relationship satisfied by the continuous cumulative value of water and sediment and the extreme value is basically consistent, and there is no trend change in the double cumulative curve. On the contrary, when the test value P is less than 0.05, it indicates that the deviation distribution significantly deviates from the symmetric interval centered at 0. At this time, the linear relationship between the continuous cumulative value of water and sediment and the extreme value has a large difference, and there is a trend change in the double cumulative curve.

[0035] The specific process of selecting the mutation point of the double cumulative curve and completing the analysis of the trend change of water and sediment in the basin is as follows. When there is a trend change in the double cumulative curve of water and sediment in the basin, the double cumulative curve and the regression curve of the extreme value form a closed triangle. The vertex of the triangle outside the extreme value is the mutation point. The change trend of the deviation between the cumulative value and the regression curve of the extreme value with the increase of the cumulative value of runoff is that it first increases and then decreases and approaches 0. The extreme point of the deviation sequence corresponds to the mutation point of the water and sediment trend. To facilitate the selection of the mutation point of the double cumulative curve and eliminate the influence of different change trends on the positive and negative values of the deviation, the deviation sequence is squared, and all deviations are converted into positive values.

[0036] λ” = {λ'1 2 , λ'2 2 ... λ' n 2} (10)

[0037] λ” is the squared sequence of the homogenized deviation. The maximum value of λ” corresponds to the mutation point of the double cumulative curve. According to the position of the mutation point of the double cumulative curve, the water and sediment trend in the basin is divided into the natural reference period and the response period. To test whether there is another change in the water and sediment trend during the response period, the improved double cumulative curve method should be used again in combination with the water and sediment sequence after the mutation point to analyze the trend change until all the mutation points of the water and sediment trend are found.

[0038] Second aspect, an embodiment of the present application provides a system for analyzing the trend change of water and sediment in a basin. The system includes: a memory and a processor. The memory includes a program for the method of analyzing the trend change of water and sediment in a basin. When the program for the method of analyzing the trend change of water and sediment in a basin is executed by the processor, the following steps are implemented: calculating the continuous cumulative values of the runoff and sediment transport volume in the basin over the same period of time with respect to time; respectively using the cumulative values of the runoff and sediment transport volume as the horizontal axis and the vertical axis to plot a double cumulative curve; establishing a linear regression in combination with the extreme values of the cumulative values of water and sediment in the basin, and then based on the deviation distribution between the water and sediment cumulative value samples and the regression curve, judging the characteristics of the trend change of water and sediment in the sample space; calculating the sample deviation of the water and sediment cumulative value; calculating the deviation sequence corresponding to the cumulative value of the sediment transport volume; homogenizing the deviation sequence by defining a scale scaling factor according to the magnitude of the absolute value of the deviation between the cumulative value and the regression curve; selecting the mutation points of the double cumulative curve to complete the analysis of the trend change of water and sediment in the basin.

[0039] Third aspect, an embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores program codes. When the program codes are executed by a processor, the steps of the method for analyzing the trend change of water and sediment in the basin as described above are implemented.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] Improve accuracy: By improving the traditional double cumulative curve method, the non-linear changes, mutation points and trend turning points in the water-sediment relationship can be more accurately identified, thereby improving the accuracy and reliability of the analysis results.

[0042] Enhance sensitivity: The improved method can more sensitively capture the subtle changes in the water-sediment relationship, including seasonal changes, the impacts of human activities (such as reservoir construction, soil and water conservation measures) and extreme climate events on the water-sediment relationship in the basin, providing more detailed data support for basin management and decision-making.

[0043] Widen the application scope: The traditional double cumulative curve method may be limited by specific conditions or scenarios, while the improved method can be more widely applied to different types of basins, data with different time scales and more complex natural and human interference environments by introducing new algorithms or data processing technologies. Description of the Drawings

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is the flowchart of the method of this application;

[0046] Figure 2 It is the schematic diagram of the double cumulative curve;

[0047] Figure 3 It is the schematic diagram of the change trend of the cumulative curve;

[0048] Figure 4 It is the water and sediment double cumulative curve graph of the lower reaches of the Jinsha River Basin;

[0049] Figure 5 It is the process graph of the change of the deviation of the water and sediment cumulative value with time in the lower reaches of the Jinsha River Basin;

[0050] Figure 6 It is the distribution graph of the cumulative value deviation and homogenization deviation in the lower reaches of the Jinsha River Basin after 2000. Specific implementation manners

[0051] Next, the technical solutions in the embodiments of this application will be described in conjunction with the accompanying drawings in the embodiments of this application. It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0052] The term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0053] The terms "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and cannot be understood as indicating or implying relative importance, nor can it be understood as requiring or implying any actual relationship or order between these entities or operations.

[0054] Please refer to Figure 1 , a method for analyzing the trend change of water and sediment in a basin, including the following steps:

[0055] Calculate the continuous cumulative values of the runoff and sediment transport in the basin over the same period with respect to time;

[0056] Respectively use the cumulative values of runoff and sediment transport as the horizontal axis and the vertical axis to draw a double cumulative curve;

[0057] Establish a linear regression by combining the extreme values of the basin water and sediment cumulative values, and then judge the characteristics of the basin water and sediment trend changes in the sample space based on the deviation distribution between the water and sediment cumulative value samples and the regression curve;

[0058] Calculate the sample deviation of the water and sediment cumulative values;

[0059] Calculate the deviation sequence corresponding to the cumulative sediment transport value;

[0060] According to the absolute value of the deviation between the cumulative value and the regression curve, define a scale factor to homogenize the deviation sequence;

[0061] Select the mutation points of the double cumulative curve to complete the analysis of the basin water and sediment trend changes.

[0062] The specific calculation of the continuous cumulative values of the basin runoff and sediment transport over time is as follows,

[0063]

[0064] Q’ is the continuous cumulative value of the basin runoff, Qi is the basin runoff in the i-th year of the statistical sequence, n is the number of samples in the statistical sequence, S’ is the continuous cumulative value of the basin sediment transport, and Si is the basin sediment transport in the i-th year of the statistical sequence.

[0065] The specific method of establishing a linear regression by combining the extreme values of the basin water and sediment cumulative values, and then judging the characteristics of the basin water and sediment trend changes in the sample space based on the deviation distribution between the water and sediment cumulative value samples and the regression curve is as follows,

[0066] Since the continuous cumulative values of water and sediment are both monotonically increasing sequences, and the maximum and minimum values correspond to the two ends of the sequence respectively, the linear regression expression of the basin water and sediment cumulative values is:

[0067] S' i = a0Q' i + S'1 (3)

[0068]

[0069] S’ i and Q’ i correspond to the i-th values in the cumulative sediment transport and runoff value sequences respectively, a0 is the slope of the linear regression, S’1 is the initial value of the cumulative sediment transport value, n is the number of samples in the basin water and sediment sequence, Q’1 is the initial value of the cumulative runoff value, S’ n is the end value of the cumulative sediment transport value, and Q’ n is the end value of the cumulative runoff value.

[0070] The specific calculation of the sample deviation of the water and sediment cumulative values is as follows,

[0071] λ i= S' i -S'1 - a0Q' i (5)

[0072] λ i is the deviation between the cumulative sediment transport volume of the i-th and the linear regression of the extreme value.

[0073] Specifically, the deviation sequence corresponding to the calculated cumulative sediment transport volume is

[0074] λ = {λ1, λ2... λ n} (6)

[0075] λ is the deviation sequence corresponding to the annual cumulative water and sediment value.

[0076] Specifically, homogenizing the deviation sequence by defining a scale factor according to the absolute value of the deviation between the cumulative value and the regression curve is

[0077] λ' i = λ i ·η i (7)

[0078]

[0079] λ i ’ is the homogenized value corresponding to the i-th deviation, and η i is the scale factor corresponding to the deviation λ i ,

[0080] When the deviation is less than 0, the scale factor has a positive correlation with the deviation magnitude; when the deviation is equal to 0, the scale factor is also 0; when the deviation is greater than 0, the scale factor has a negative correlation with the deviation magnitude. Therefore, the greater the deviation of the cumulative value from the extreme value regression curve, the smaller the scale factor. By scaling the extreme outliers, the homogenized deviation sequence can effectively reduce the influence of water and sediment fluctuations on trend judgment, and the standardized deviation sequence is calculated using (7).

[0081] λ' = {λ1', λ2'... λ n '} (9)

[0082] Let λ’ be the homogenized deviation sequence corresponding to the annual cumulative value of water and sediment. The statistical t-test method is used to determine whether there is a significant difference between the homogenized deviation sequence and the normal distribution centered at 0. When the test value P obtained from the t-test is greater than 0.05, it indicates that there is no significant difference between the distribution center of the standardized deviation sequence and 0, and the deviation is distributed within the finite boundaries on both sides of 0. The linear relationship satisfied by the continuous cumulative value of water and sediment and the extreme value is basically consistent, and there is no trend change in the double cumulative curve. On the contrary, when the test value P is less than 0.05, it indicates that the deviation distribution significantly deviates from the symmetric interval centered at 0. At this time, the linear relationship between the continuous cumulative value of water and sediment and the extreme value has a large difference, and there is a trend change in the double cumulative curve.

[0083] The selection of the mutation point of the double cumulative curve and the completion of the analysis of the trend change of water and sediment in the basin are specifically as follows. When there is a trend change in the double cumulative curve of water and sediment in the basin, the double cumulative curve and the regression curve of the extreme value form a closed triangle. The vertex of the triangle outside the extreme value is the mutation point. The change trend of the deviation between the cumulative value and the regression curve of the extreme value with the increase of the cumulative value of runoff is that it first increases and then decreases and approaches 0. The extreme value point of the deviation sequence corresponds to the mutation point of the water and sediment trend. To facilitate the selection of the mutation point of the double cumulative curve and eliminate the influence of different change trends on the positive and negative values of the deviation, the deviation sequence is squared, and all deviations are converted into positive values.

[0084] λ” = {λ'1 2 , λ'2 2 ... λ' n 2} (10)

[0085] λ” is the squared sequence of the homogenized deviation. The maximum value of λ” corresponds to the mutation point of the double cumulative curve. According to the position of the mutation point of the double cumulative curve, the water and sediment trend in the basin is divided into the natural reference period and the response period. To test whether there is a change in the water and sediment trend during the response period, the improved double cumulative curve method should be used again in combination with the water and sediment sequence after the mutation point to analyze the trend change until all the mutation points of the water and sediment trend are found.

[0086] Using the method proposed in this patent, calculate the mutation year of the runoff process in the Jinsha River Basin and the change law of the annual runoff process. The area of the Jinsha River Basin is 500,000 km 2 , accounting for 27.8% of the total area of the Yangtze River Basin. It is an important source of water and sediment in the upper reaches of the Yangtze River. With the cascade hydropower development in the lower reaches of the Jinsha River, the runoff process at the basin outlet has changed significantly. Based on the runoff and sediment transport at the hydrological station of Pingshan at the basin outlet in the lower reaches of the Jinsha River, the improved double cumulative curve method is used to analyze the trend change of water and sediment in the lower reaches of the Jinsha River Basin.

[0087] First, analyze the water and sediment variation trend in the lower reaches of the Jinsha River Basin according to the double cumulative curve method. Use equations (1) and (2) to calculate the continuous cumulative values of water and sediment in the basin, and draw the double cumulative curve as Figure 4 shown. By observing the variation trend of the water-sediment double cumulative curve, it can be seen that there are obvious changes in the water-sediment trend in the lower reaches of the Jinsha River Basin, and the mutation point is around 2013. Before 2013, the slope of the double cumulative curve was 17.073, and the fitting accuracy of linear regression was 0.997; after 2013, the slope of the double cumulative curve was 0.105, and the fitting degree of linear regression was 0.986. The slope of the double cumulative curve decreased by 99.385% before and after 2013, indicating that the sediment concentration in the basin decreased significantly after 2013.

[0088] Using the improved double cumulative curve method proposed in this patent, use equations (5) to (8) to calculate the deviation and mean deviation of the linear regression of the water-sediment cumulative value and extreme value in the lower reaches of the Jinsha River Basin, and analyze the change process of both over time. The results are as Figure 5 shown. The distribution range of the cumulative value deviation from 1954 to 2019 is 957.4 million tons, and the average value of the homogenized deviation is 386.3 million tons.

[0089] According to the mutation point selection criterion in the improved double cumulative curve method, the maximum value of the homogenized deviation sequence is the mutation point of the water-sediment trend in the basin. Figure 6 The overall change trend of the mean deviation and deviation is the same, but it can greatly reduce the influence of outliers on the overall change trend. The maximum values of the corresponding squared sequences of the homogenized deviation are all in 2000, indicating that 2000 is the first water-sediment mutation year in the lower reaches of the Jinsha River Basin. After obtaining the first water-sediment mutation year in the lower reaches of the Jinsha River Basin, use the improved double cumulative curve method to further determine whether there is a trend change in the double cumulative curve from 2000 to 2019. Taking the water and sediment volume in the lower reaches of the Jinsha River in 2000 as the initial value, calculate the distribution of the cumulative value deviation and homogenized deviation in the basin after 2000. The results are as Figure 6 shown. The positions of the maximum values corresponding to the cumulative value deviation and homogenized deviation are both in 2012. Therefore, 2012 is another mutation point of the water-sediment trend change in the lower reaches of the Jinsha River Basin.

[0090] In summary, there are two mutation points in the water-sediment trend change in the lower reaches of the Jinsha River Basin, which are located in 2000 and 2012 respectively. The positions of the mutation points are the same as Figure 3It is basically consistent with the water and sediment variation process in the lower reaches of the Jinsha River. By comparing the judgment results of the improved double mass curve method and the original method, the theoretical accuracy of the improved double mass curve method is higher, and it can accurately locate the positions of two mutation points, while the original method ignores the water and sediment mutation point in 2000. Combining engineering experience to analyze the main reasons for the sudden changes in the water and sediment trends in the lower reaches of the Jinsha River in 2000 and 2012, in 2000, a large reservoir (Ertan Hydropower Station) was built on the Yalong River, which is about the main tributary of the general water and sediment inflow in the lower reaches of the Jinsha River. In 2012, the first large reservoir (Xiluodu Hydropower Station) was built on the main stream of the lower reaches of the Jinsha River. The completion of these two large hydropower hubs has led to a significant decrease in the sediment concentration of the runoff in the lower reaches of the Jinsha River and a sudden change in the water and sediment trend.

[0091] The embodiment of the present application provides a system for analyzing the change trend of water and sediment in a basin. The system includes: a memory and a processor. The memory includes a program for the method of analyzing the change trend of water and sediment in a basin. When the program for the method of analyzing the change trend of water and sediment in a basin is executed by the processor, the following steps are implemented: calculating the continuous cumulative values of the runoff and sediment transport volume in the basin over the same period of time; respectively using the cumulative values of the runoff and sediment transport volume as the horizontal axis and the vertical axis to draw a double mass curve; establishing a linear regression by combining the extreme values of the cumulative values of water and sediment in the basin, and then based on the deviation distribution between the water and sediment cumulative value samples and the regression curve, judging the change characteristics of the water and sediment trend in the sample space; calculating the sample deviation of the water and sediment cumulative value; calculating the deviation sequence corresponding to the cumulative value of the sediment transport volume; performing homogenization processing on the deviation sequence according to the absolute value of the deviation between the cumulative value and the regression curve by defining a scale scaling factor; selecting the mutation points of the double mass curve to complete the analysis of the change trend of water and sediment in the basin.

[0092] The embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores program codes. When the program codes are executed by a processor, the steps of the method for analyzing the change trend of water and sediment in a basin as described above are implemented.

[0093] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0094] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, as well as the combination of flows and / or blocks in the flowchart and / or block diagram. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0095] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0097] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0098] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0099] A computer-readable medium includes both permanent and non-permanent, removable and non-removable media that can store information by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer-readable medium does not include transitory media such as modulated data signals and carrier waves.

[0100] The above are only embodiments of the present application and are not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for analyzing the trend change of water and sediment in a river basin, characterized in that: The following steps are involved: Calculate the continuous cumulative values ​​of basin runoff and sediment transport over time in the same period; A double accumulation curve is drawn with the accumulated values ​​of runoff and sediment transport as the horizontal axis and vertical axis respectively; A linear regression is established based on the extreme values ​​of the water and sediment accumulation values ​​in the basin, and then the water and sediment trend change characteristics of the basin in the sample space are determined based on the deviation distribution between the water and sediment accumulation value samples and the regression curve; Calculate sample deviation of water and sediment accumulation values; Calculate the deviation sequence corresponding to the cumulative value of sediment transport; According to the absolute value of the deviation between the cumulative value and the regression curve, the scale factor is defined to homogenize the deviation sequence; Select the mutation points of the double cumulative curve to complete the analysis of water and sediment trend changes in the basin.

2. A method for analyzing water and sediment trend changes in a river basin according to claim 1, characterized in that: The continuous cumulative value of the basin runoff and sediment transport over time in the calculation period is specifically: Q' is the continuous cumulative value of basin runoff, Qi is the basin runoff in the i-th year in the statistical sequence, n is the number of samples in the statistical sequence, S' is the continuous cumulative value of basin sediment discharge, and Si is the basin sediment discharge in the i-th year in the statistical sequence.

3. A method for analyzing water and sediment trend changes in a river basin according to claim 1, characterized in that: The linear regression is established in combination with the extreme value of the water and sediment accumulation value of the basin, and then based on the deviation distribution of the water and sediment accumulation value sample and the regression curve, the water and sediment trend change characteristics of the basin in the sample space are judged as follows: Since the continuous accumulation values ​​of water and sediment are all monotonically increasing sequences, the maximum and minimum values ​​correspond to the two ends of the sequence, so the linear regression expression of the water and sediment accumulation value in the basin is: S' i =a0Q' i +S'1 (3) S' i With Q' i They correspond to the i-th value in the sediment discharge and runoff cumulative value sequence, a0 is the slope of linear regression, S'1 is the initial value of the sediment discharge cumulative value, n is the number of samples of the watershed water and sediment sequence, Q'1 is the initial value of the runoff cumulative value, S' n is the terminal value of the accumulated sediment transport, Q' n It is the terminal value of runoff accumulation.

4. A method for analyzing water and sediment trend changes in a river basin according to claim 1, characterized in that: The sample deviation for calculating the water and sediment accumulation value is specifically: l i =S' i -S'1-a0Q' i (5) λ i is the deviation between the cumulative value of the ith sediment discharge and the extreme value linear regression.

5. A method for analyzing water and sediment trend changes in a river basin according to claim 1, characterized in that: The deviation sequence corresponding to the calculated sediment transport cumulative value is specifically: λ={λ1,λ2...λ n } (6) λ is the deviation sequence corresponding to the annual water and sediment accumulation value.

6. A method for analyzing water and sediment trend changes in a river basin according to claim 1, characterized in that: According to the absolute value of the deviation between the cumulative value and the regression curve, the scale factor is defined to homogenize the deviation sequence, specifically, l' i =λ i ·or i (7) λ i ' is the homogenization value corresponding to the i-th deviation, η i is the deviation λ i The corresponding scaling factor, When the deviation is less than 0, the scale scaling factor is positively correlated with the deviation size; When the deviation is equal to 0, the scale factor is also 0; When the deviation is greater than 0, the scale scaling factor is negatively correlated with the deviation. Therefore, the more the cumulative value deviates from the extreme value regression curve, the smaller the scale scaling factor. By scaling the extreme outliers, the homogenized deviation sequence can effectively reduce the impact of water and sediment fluctuations on trend judgment. The standardized deviation sequence is calculated using (7). λ'={λ1',λ2'...λ n '} (9) λ' is the homogenized deviation sequence corresponding to the accumulated water and sediment values ​​each year. The statistical t-test method is used to determine whether the homogenized deviation sequence is significantly different from the normal distribution centered on 0. When the test value P obtained by the t-test is greater than 0.05, it means that there is no significant difference between the distribution center of the standardized deviation sequence and 0, and the deviation is distributed within the limited boundaries on both sides of 0. The linear relationship between the continuous accumulated water and sediment values ​​and the extreme values ​​is basically consistent, and there is no trend change in the double accumulation curve; on the contrary, the test value P is less than 0.05, indicating that the deviation distribution deviates significantly from the symmetrical interval centered on 0. At this time, the linear relationship between the continuous accumulated water and sediment values ​​and the extreme values ​​is quite different, and there is a trend change in the double accumulation curve.

7. A method for analyzing water and sediment trend changes in a river basin according to claim 1, characterized in that: The method of selecting the mutation point of the double cumulative curve to complete the analysis of the trend change of water and sediment in the basin is as follows: when the double cumulative curve of water and sediment in the basin changes in trend, the double cumulative curve and the extreme value regression curve form a closed triangle, wherein the triangle vertex outside the extreme value is the mutation point, and the deviation between the cumulative value and the extreme value regression curve increases first and then decreases and approaches 0 as the cumulative value of runoff increases, wherein the extreme value point of the deviation sequence corresponds to the mutation point of the water and sediment trend. In order to facilitate the selection of the mutation point of the double cumulative curve and eliminate the influence of different change trends on the positive and negative values ​​of the deviation, the deviation sequence is subjected to quadratic processing to convert all deviations into positive values. λ” is the quadratic sequence of homogenization deviation. The maximum value of λ” corresponds to the mutation point of the double cumulative curve. According to the position of the mutation point of the double cumulative curve, the water-sediment trend in the basin is divided into a natural reference period and a response period. In order to test whether the water-sediment trend changes again during the response period, the water-sediment sequence after the mutation point should be combined, and the improved double cumulative curve method should be used again to analyze the trend change until all the mutation points of the water-sediment trend are found.

8. A watershed water and sediment trend change analysis system, characterized in that: The system comprises: a memory and a processor, wherein the memory comprises a program of a method for analyzing a trend change of water and sediment in a watershed, and when the program of the method for analyzing a trend change of water and sediment in a watershed is executed by the processor, the following steps are implemented: calculating the continuous cumulative values ​​of the runoff and sediment transport in the watershed over time in the same period; drawing a double cumulative curve with the cumulative values ​​of runoff and sediment transport as the horizontal axis and the vertical axis respectively; establishing a linear regression in combination with the extreme values ​​of the cumulative values ​​of water and sediment in the watershed, and judging the trend change characteristics of water and sediment in the watershed in the sample space based on the deviation distribution of the water and sediment cumulative value samples and the regression curve; calculating the sample deviation of the water and sediment cumulative value; calculating the deviation sequence corresponding to the cumulative value of sediment transport; defining a scale scaling factor according to the absolute value of the deviation between the cumulative value and the regression curve to homogenize the deviation sequence; selecting mutation points of the double cumulative curve to complete the analysis of the trend change of water and sediment in the watershed.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program codes, and when the program codes are executed by a processor, the steps of the method for analyzing watershed water and sediment trend changes as described in any one of claims 1 to 7 are implemented.

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