Method, system, device and storage medium for determining low-flow flow in a small watershed

Abstract

The present invention discloses a method, system, device and storage medium for determining low-flow flow in a small watershed. The method comprises: obtaining precipitation information and digital elevation model data of relevant rain gauge stations in the watershed; determining the annual precipitation and monthly precipitation of the catchment range by the Thiessen polygon method according to the precipitation information and the digital elevation model data; fitting the frequency distribution of the annual precipitation by the Pearson curve to determine the first model; obtaining the multi-year average precipitation and the annual runoff characteristic value of the center of the watershed; determining the runoff coefficient under a given guarantee rate based on the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value based on the first model; determining the monthly total runoff according to the runoff coefficient and the monthly precipitation; determining the low-flow flow data according to the monthly total runoff. The embodiment of the present application can design the low-flow flow for small watershed areas without data and improve the accuracy of flow design. The method can be widely used in the field of computer technology.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular to a method, system, device and storage medium for determining low-flow flow in a small watershed. Background Art

[0002] Low-water flow refers to a special form of river runoff during the dry season. The size of low-water flow often determines the water supply capacity and water environment capacity of the river, and is of great significance to the urban development of a region. The calculation of the designed low-water flow is the basis for analyzing the water supply capacity of the river and the pollution absorption capacity of the water area. In related technologies, the following three methods are usually used to design low-water flow: one is the hydrological analysis method, which is obtained by frequency analysis based on the measured long-sequence hydrological data; the second is the hydrological analogy method, which is obtained by transplanting the hydrological analysis results of adjacent basins; the third is the hydrological model method, which uses precipitation data and similar basin model parameters to transplant, obtain long-series flow data, and then apply the frequency analysis method to obtain it. The hydrological analysis method and the hydrological analogy method have high requirements for the measured hydrological data of the basin or adjacent basins, and cannot be applied to areas without hydrological data; the hydrological model method has high requirements for the transplantation of model parameters, and the calculation is complex and the accuracy is not high. In water conservancy project construction and river basin management, most of the projects and measures are located in small watersheds, which are mostly data-free areas lacking hydrological data and river basin geographic information, or even without hydrological stations in nearby river basins for transplantation. The above-mentioned method is used to design low-flow flow in the above-mentioned areas, which results in complex calculations and low accuracy of design results. Summary of the invention

[0003] The purpose of the present invention is to solve one of the technical problems existing in the prior art to at least a certain extent.

[0004] To this end, an object of the present invention is to provide a method, system, device and storage medium for determining low-flow flow in a small watershed with high accuracy.

[0005] In order to achieve the above technical objectives, the technical solutions adopted by the embodiments of the present invention include:

[0006] On the one hand, an embodiment of the present invention provides a method for determining low-flow flow in a small watershed, comprising the following steps:

[0007] The method for determining the low-flow flow of a small watershed in an embodiment of the present invention comprises: obtaining precipitation information and digital elevation model data of relevant rain gauge stations in the watershed; determining the annual precipitation and monthly precipitation of the catchment range by the Thiessen polygon method according to the precipitation information and digital elevation model data; fitting the frequency distribution of the annual precipitation by the Pearson curve to determine the first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate; obtaining the multi-year average precipitation and annual runoff characteristic value of the center of the watershed; determining the runoff coefficient under a given guarantee rate based on the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value based on the first model; determining the monthly total runoff according to the runoff coefficient and the monthly precipitation; and determining the low-flow flow data according to the monthly total runoff. The embodiment of the present application decomposes the precipitation process by the runoff coefficient and the monthly precipitation, and determines the designed low-flow flow by the monthly total runoff, which can design the low-flow flow for small watershed areas without data and improve the accuracy of flow design.

[0008] In addition, the method for determining low-flow flow in a small watershed according to the above embodiment of the present invention may also have the following additional technical features:

[0009] Furthermore, the method for determining the low-water flow of a small watershed in an embodiment of the present invention, wherein the annual precipitation and monthly precipitation of the catchment area are determined by the Thiessen polygon method based on the precipitation information and the digital elevation model data, comprising:

[0010] The area weight of each rainfall station is determined by the Thiessen polygon method;

[0011] Determine the monthly precipitation of the catchment area according to the monthly precipitation of each rain gauge station and the area weight;

[0012] The annual precipitation of the catchment area is determined according to the annual precipitation of each rain gauge station and the area weight.

[0013] Furthermore, in one embodiment of the present invention, determining the area weight of each rainfall station by using the Thiessen polygon method includes:

[0014] Determining a catchment area based on the digital elevation model data;

[0015] Adding the areas of all the points to be estimated within the catchment area and adjacent to the first rainfall station to obtain a first area;

[0016] An area weight of the first rain gauge is determined according to the first area and the catchment area.

[0017] Furthermore, in one embodiment of the present invention, the precipitation information of the relevant rain gauge stations in the watershed includes multi-year precipitation information; and determining the monthly total runoff according to the runoff coefficient and the monthly precipitation includes:

[0018] Obtain annual precipitation information for the first year; the first year is any year among multiple years;

[0019] Determine the first year's precipitation and the first year's monthly precipitation based on the annual precipitation information;

[0020] Determine the monthly allocation ratio for the first year based on the precipitation in the first year and the monthly precipitation in the first year;

[0021] Determine the runoff coefficient for the first year based on the first model according to the precipitation in the first year;

[0022] Determine the monthly total runoff volume of the first year according to the runoff coefficient of the first year and the monthly allocation ratio of the first year;

[0023] The first year is updated, and the annual precipitation information of the first year is returned until the monthly total runoff of all years is obtained; the first year after the update is any year that has not been traversed in multiple years.

[0024] Further, in one embodiment of the present invention, determining the total monthly runoff volume in the first year according to the runoff coefficient in the first year and the monthly allocation ratio in the first year includes:

[0025] Determine the total runoff volume in the first year based on the runoff coefficient and the catchment area in the first year;

[0026] Obtaining a base flow coefficient, and determining the base flow in the first year according to the total runoff in the first year and the base flow coefficient;

[0027] Evenly distribute the first year's base flow to each month to determine the first year's monthly base flow;

[0028] Determine the surface runoff in the first year according to the total runoff in the first year and the base flow in the first year;

[0029] Allocate the surface runoff volume of the first year to each month according to the monthly allocation ratio of the first year to determine the monthly surface runoff volume of the first year;

[0030] The total monthly runoff in the first year is determined according to the monthly base flow in the first year and the monthly surface runoff in the first year.

[0031] Further, in one embodiment of the present invention, determining the runoff coefficient for the first year based on the first model according to the precipitation in the first year includes:

[0032] Determining a first-year guarantee rate according to the first-year precipitation and based on the first model;

[0033] According to the first year guarantee rate and based on the first model, determining the first year runoff depth;

[0034] Based on the principle of the same frequency of precipitation and runoff in a small watershed, the runoff coefficient of the first year is determined according to the runoff depth and precipitation of the first year.

[0035] Further, in one embodiment of the present invention, determining the low water flow data according to the monthly total runoff includes:

[0036] Determine the minimum value of the monthly total runoff as the average flow rate of the driest month over many years; the low water flow data includes the average flow rate of the driest month over many years;

[0037] or,

[0038] Determine the distance set between the annual guarantee rate and the preset guarantee rate;

[0039] Determine the second year corresponding to the minimum distance in the distance set;

[0040] The minimum value of the total monthly runoff in the second year is determined as the average flow of the driest month with a guaranteed rate; the low water flow data includes the average flow of the driest month with a guaranteed rate.

[0041] Further, in one embodiment of the present invention, the first model is determined by the following formula:

[0042]

[0043] in, Γ(α) is the complete Γ function, Cv is the coefficient of variation, and Cs is the coefficient of deviation; C s = k × C v ; P is the first annual precipitation.

[0044] Furthermore, in one embodiment of the present invention, the method further comprises:

[0045] Through the least square method, k is adjusted, and then the first model is adjusted.

[0046] On the other hand, an embodiment of the present invention provides a system for determining low-flow flow in a small watershed, comprising:

[0047] The first module is used to obtain precipitation information and digital elevation model data of relevant rain gauge stations in the basin;

[0048] The second module is used to determine the annual precipitation and monthly precipitation of the catchment area by using the Thiessen polygon method according to the precipitation information and the digital elevation model data;

[0049] The third module is used to fit the frequency distribution of the annual precipitation through the Pearson curve to determine the first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate;

[0050] The fourth module is used to obtain the multi-year average precipitation and annual runoff characteristic values ​​in the basin center;

[0051] A fifth module is used to determine the runoff coefficient under a given guarantee rate based on the first model according to the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value;

[0052] The sixth module is used to determine the monthly total runoff according to the runoff coefficient and the monthly precipitation;

[0053] The seventh module is used to determine the low water flow data according to the monthly total runoff.

[0054] On the other hand, an embodiment of the present invention provides a device for determining low-flow flow in a small watershed, comprising:

[0055] at least one processor;

[0056] at least one memory for storing at least one program;

[0057] When the at least one program is executed by the at least one processor, the at least one processor implements the above-mentioned method for determining the low water flow rate of a small watershed.

[0058] On the other hand, an embodiment of the present invention provides a storage medium storing a program executable by a processor, wherein the program executable by the processor is used to implement the above-mentioned method for determining the low-flow flow of a small watershed when executed by the processor.

[0059] The method of the embodiment of the present invention includes: obtaining precipitation information and digital elevation model data of relevant rain gauge stations in the basin; determining the annual precipitation and monthly precipitation of the catchment range through the Thiessen polygon method according to the precipitation information and digital elevation model data; fitting the frequency distribution of the annual precipitation through the Pearson curve to determine the first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate; obtaining the multi-year average precipitation and annual runoff characteristic value of the basin center; determining the runoff coefficient under a given guarantee rate based on the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value based on the first model; determining the monthly total runoff according to the runoff coefficient and the monthly precipitation; determining the low flow flow data according to the monthly total runoff. The embodiment of the present application decomposes the precipitation process through the runoff coefficient and the monthly precipitation, and determines the designed low flow flow through the monthly total runoff, which can design the low flow flow for small basins without data and improve the accuracy of flow design. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0061] Figure 1 A schematic flow chart of an embodiment of a method for determining low-flow flow in a small watershed provided by the present invention;

[0062] Figure 2 A schematic flow chart of another embodiment of a method for determining low-flow flow in a small watershed provided by the present invention;

[0063] Figure 3 A schematic diagram of an embodiment of the Thiessen polygon method provided by the present invention;

[0064] Figure 4 A schematic diagram of querying an embodiment of the center position and contour lines of a watershed provided by the present invention;

[0065] Figure 5 A schematic diagram of the structure of an embodiment of a system for determining low-flow flow in a small watershed provided by the present invention;

[0066] Figure 6 A schematic structural diagram of an embodiment of a device for determining low-flow flow in a small watershed provided by the present invention. DETAILED DESCRIPTION

[0067] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0068] Low-water flow refers to a special form of river runoff during the dry season. The size of low-water flow often determines the water supply capacity and water environment capacity of the river, and is of great significance to the urban development of a region. The calculation of the designed low-water flow is the basis for the analysis of the water supply capacity of the river and the pollution absorption capacity of the water area. For example, the calculation of the pollution absorption capacity of the water area requires the calculation of the average flow of the driest month with a 90% guarantee rate or the average flow of the driest month in the past ten years as the design flow. The following three methods are usually used to design the low-water flow: the first is the hydrological analysis method, which is obtained by the frequency analysis method based on the measured long-sequence hydrological data; the second is the hydrological analogy method, which is obtained by transplanting the hydrological analysis results of the adjacent basin; the third is the hydrological model method, which uses precipitation data and similar basin model parameters to obtain long-series flow data, and then applies the frequency analysis method to obtain it. The hydrological analysis method and the hydrological analogy method have high requirements for the measured hydrological data of the basin or adjacent basin, and cannot be applied to areas without hydrological data; the hydrological model method has high requirements for the transplantation of model parameters, and the calculation is complex and the accuracy is not high. In water conservancy project construction and river basin management, most of the projects and measures are located in small watersheds, and most small watersheds are data-free areas that lack hydrological data and river basin geographic information, and even have no hydrological stations in nearby watersheds for transplantation. Designing low-flow flow is one of the indispensable work contents. Although the country continues to improve the hydrological monitoring station network, the coverage is still insufficient and the accumulation of hydrological data is a long process. Therefore, it is very necessary to develop methods for designing low-flow flow in small watersheds without data.

[0069] Due to the high cost of construction and management of hydrological stations, hydrological data are relatively scarce, while the construction and management costs of rain gauges are low, and precipitation data are relatively complete and easy to obtain. For small watersheds without hydrological data, hydrological analysis methods are difficult to adapt to the calculation of designed low-flow flow. At present, the hydrological analogy method or hydrological model method is mainly used to design low-flow flow in small watersheds without data. Under the premise that the adjacent (similar) watershed cannot be guaranteed, the hydrological analogy method or hydrological model method is carried out for analysis and calculation, and the calculation results are unreliable. Therefore, a solution for calculating the designed low-flow flow through long-sequence monthly precipitation data is developed, which can be applied to the calculation of designed low-flow flow in small watersheds without data.

[0070] The following describes in detail the method and system for determining low-flow flow in a small watershed according to an embodiment of the present invention with reference to the accompanying drawings. First, the method for determining low-flow flow in a small watershed according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0071] Reference Figure 1 In an embodiment of the present invention, a method for determining low-flow flow in a small watershed is provided. The method for determining low-flow flow in a small watershed in an embodiment of the present invention can be applied to a terminal, a server, or software running in a terminal or a server. The terminal can be a tablet computer, a laptop computer, a desktop computer, etc., but is not limited thereto. The server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The method for determining low-flow flow in a small watershed in an embodiment of the present invention mainly includes the following steps:

[0072] S100: Obtain precipitation information and digital elevation model data of relevant rain gauge stations in the basin;

[0073] S200: Determine the annual precipitation and monthly precipitation of the catchment area by using the Thiessen polygon method according to the precipitation information and the digital elevation model data;

[0074] S300: fitting the frequency distribution of the annual precipitation through a Pearson curve to determine a first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate;

[0075] S400: Obtain the multi-year average precipitation and annual runoff characteristic values ​​in the basin center;

[0076] S500: determining a runoff coefficient under a given guarantee rate based on the first model according to the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value;

[0077] S600: Determine the monthly total runoff according to the runoff coefficient and the monthly precipitation;

[0078] S700: Determine low water flow data according to the monthly total runoff.

[0079] In some possible implementations, the precipitation information of relevant rain gauge stations in the basin can be obtained through relevant data information, and the digital elevation model data can be obtained through a public DEM database. The embodiment of the present application can fit the frequency distribution of the precipitation series through the Pearson III curve function. By consulting the atlas of water resources investigation and evaluation results in the area, the second annual precipitation of the basin center and the first year runoff characteristic value are obtained, and then the monthly flow process is calculated through the monthly precipitation process of the i-th year.

[0080] It can be understood that the present invention solves the problem of calculating the design low-flow flow in small watersheds where hydrological data are difficult to obtain. In the case of a watershed without hydrological data or without adjacent (similar) watersheds, the present invention proposes a method for decomposing the annual precipitation process through the runoff coefficient and the base flow coefficient to obtain the annual distribution process of runoff, based on the principle of the same frequency of precipitation and runoff in small watersheds, and then derives the design low-flow flow. This method can be used to quickly calculate the design low-flow flow in small watersheds without data, meeting the needs of small watershed water conservancy project design and river and lake management.

[0081] Optionally, in one embodiment of the present invention, the determining the annual precipitation and monthly precipitation of the catchment area by using the Thiessen polygon method according to the precipitation information and the digital elevation model data includes:

[0082] The area weight of each rainfall station is determined by the Thiessen polygon method;

[0083] Determine the monthly precipitation of the catchment area according to the monthly precipitation of each rain gauge station and the area weight;

[0084] The annual precipitation of the catchment area is determined according to the annual precipitation of each rain gauge station and the area weight.

[0085] The embodiment of the present application determines the area weight of each rain gauge station through Thiessen polygons, and then determines the annual precipitation and monthly precipitation within the water collection range according to the multi-year precipitation information of each rain gauge station. Among them, the multi-year precipitation information of each rain gauge station includes the annual precipitation and monthly precipitation of each rain gauge station. According to the area weight, the annual precipitation and monthly precipitation of each rain gauge station are weighted and summed to determine the annual precipitation and monthly precipitation within the water collection range.

[0086] Optionally, in one embodiment of the present invention, determining the area weight of each rainfall station by using the Thiessen polygon method includes:

[0087] Determining a catchment area based on the digital elevation model data;

[0088] Adding the areas of all the points to be estimated within the catchment area and adjacent to the first rainfall station to obtain a first area;

[0089] The area weight of the first rain gauge is determined according to the first area and the catchment area; the first rain gauge is any one of the multiple rain gauges.

[0090] Optionally, in one embodiment of the present invention, the precipitation information of the relevant rain gauge stations in the watershed includes multi-year precipitation information; and determining the monthly total runoff according to the runoff coefficient and the monthly precipitation includes:

[0091] Obtain annual precipitation information for the first year; the first year is any year among multiple years;

[0092] Determine the first year's precipitation and the first year's monthly precipitation based on the annual precipitation information;

[0093] Determine the monthly allocation ratio for the first year based on the precipitation in the first year and the monthly precipitation in the first year;

[0094] Determine the runoff coefficient for the first year based on the first model according to the precipitation in the first year;

[0095] Determine the monthly total runoff volume of the first year according to the runoff coefficient of the first year and the monthly allocation ratio of the first year;

[0096] The first year is updated, and the annual precipitation information of the first year is returned until the monthly total runoff of all years is obtained; the first year after the update is any year that has not been traversed in multiple years.

[0097] In the embodiment of the present application, the multi-year precipitation information can be 10 years, 20 years, or 30 years, and the present application is not specifically limited. The embodiment of the present application can be calculated from the first year in many years, first calculating the monthly total runoff of the first year, then calculating the monthly total runoff of the second year, and so on, until the monthly total runoff calculation of each year is completed. The embodiment of the present application can also set the calculation path according to actual needs to complete the monthly total runoff of each year. It is understandable that when calculating the monthly total runoff of a certain year (such as the first year), first obtain the precipitation information of each rain gauge in the first year according to the annual precipitation information, and determine the precipitation of the first year and the monthly precipitation of the first year according to the precipitation information and the area weight of each rain gauge. That is, according to the annual precipitation information, the first-year precipitation and the first-year monthly precipitation of the first-year precipitation are determined, including: according to the annual precipitation information, the precipitation information of the rain gauge station in the first year is determined; according to the precipitation information of the rain gauge station in the first year and the area weight, the first-year precipitation and the first-year monthly precipitation of the first-year precipitation are determined. The first-year monthly allocation ratio in the embodiment of the present application is the ratio of the monthly precipitation to the annual precipitation, which is used for the subsequent runoff allocation.

[0098] Optionally, in one embodiment of the present invention, determining the total monthly runoff volume in the first year according to the runoff coefficient in the first year and the monthly allocation ratio in the first year includes:

[0099] Determine the total runoff volume in the first year based on the runoff coefficient and the catchment area in the first year;

[0100] Obtaining a base flow coefficient, and determining the base flow in the first year according to the total runoff in the first year and the base flow coefficient;

[0101] Evenly distribute the first year's base flow to each month to determine the first year's monthly base flow;

[0102] Determine the surface runoff in the first year according to the total runoff in the first year and the base flow in the first year;

[0103] Allocate the surface runoff volume of the first year to each month according to the monthly allocation ratio of the first year to determine the monthly surface runoff volume of the first year;

[0104] The total monthly runoff in the first year is determined according to the monthly base flow in the first year and the monthly surface runoff in the first year.

[0105] Optionally, in one embodiment of the present invention, determining the runoff coefficient for the first year based on the first model according to the precipitation in the first year includes:

[0106] Determining a first-year guarantee rate according to the first-year precipitation and based on the first model;

[0107] According to the first year guarantee rate and based on the first model, determining the first year runoff depth;

[0108] Based on the principle of the same frequency of precipitation and runoff in a small watershed, the runoff coefficient for the first year is determined according to the runoff depth and the precipitation in the first year.

[0109] Optionally, in one embodiment of the present invention, determining low water flow data according to the monthly total runoff includes:

[0110] Determine the minimum value of the monthly total runoff as the average flow rate of the driest month over many years; the low water flow data includes the average flow rate of the driest month over many years;

[0111] or,

[0112] Determine the distance set between the annual guarantee rate and the preset guarantee rate;

[0113] Determine the second year corresponding to the minimum distance in the distance set;

[0114] The minimum value of the total monthly runoff in the second year is determined as the average flow of the driest month with a guaranteed rate; the low water flow data includes the average flow of the driest month with a guaranteed rate.

[0115] Optionally, in one embodiment of the present invention, the first model is determined by the following formula:

[0116]

[0117] in, Γ(α) is the complete Γ function, Cv is the coefficient of variation, and Cs is the coefficient of deviation; C s = k × C v ; P is the first annual precipitation.

[0118] Optionally, in one embodiment of the present invention, the method further includes:

[0119] Through the least square method, k is adjusted, and then the first model is adjusted.

[0120] In some possible implementations, reference Figure 2 Referring to the following specific embodiment, the method for determining the low-flow flow of a small watershed proposed in the present application is described in detail, specifically, comprising the following steps:

[0121] Step 21: Collect a long series (no less than 30 years) of monthly precipitation data and the geographical location coordinates of the rain gauges within and around the catchment area of ​​the target section (i.e., the precipitation information of the basin-related rain gauges in the embodiment of the present application).

[0122] Step 22: Based on the public national 30-meter DEM database (it can be understood that the 30-meter DEM data, ASTER Global Digital Elevation Model (ASTER GDEM) is global digital elevation data, and the DEM data is completed based on the observation results of NASA's new generation earth observation satellite TERRA. The horizontal accuracy of the data is 1″), GIS software is used (for example, those skilled in the art can process it through other geographic information systems) to obtain the DEM of the catchment range above the target section, and calculate the catchment area A.

[0123] Step 23: Use GIS software and Thiessen polygon method to obtain the area weight of each rainfall station. Figure 3 As shown, the calculation method of Thiessen polygon method is as follows:

[0124] d bi =min(d b1 ,d b2 ,db3 ,Λ,d bn );

[0125]

[0126] Where: d bi The point i is the closest point to the estimated point b and the rainfall station (1,2,…,i,…,n). The value of the estimated point is the rainfall value of rainfall station i. i 、x j ,y i ,y j is the coordinate value corresponding to the rainfall station.

[0127] The weight λi of the rainfall station i is obtained by summing up the areas ΣAi (i.e., the first area in the embodiment of the present application) of all the points to be estimated within the catchment area and adjacent to the rainfall station i, and dividing it by the catchment area A.

[0128] Step 24: The annual precipitation Pi is obtained by summing up the monthly precipitation at the rain gauge, and then the annual precipitation P within the catchment area is calculated using the Thiessen polygon method.

[0129]

[0130] Step 25: Use the Pearson III curve function to fit the frequency distribution of the precipitation series. The calculation method is as follows:

[0131] The Pearson III curve function equation is (i.e., the first model in the embodiment of the present application):

[0132]

[0133] In the formula,

[0134] Γ(α) is the complete Γ function, Cv is the coefficient of variation, and Cs is the coefficient of deviation.

[0135]

[0136] C s = k × C v ;

[0137] k is a coefficient. By adjusting the k value, the Pearson III type curve can simulate the measured precipitation frequency distribution as much as possible, that is, by adjusting the k value, the accuracy of the first model is adjusted.

[0138] Step 26: Use the least squares method to calculate the k value, that is, the sum of squared errors SSE is minimized:

[0139]

[0140] Step 27: From the k value, Cs can be obtained, and then the annual precipitation P under a given guarantee rate N% (cumulative frequency) can be calculated through the Pearson III type curve function. N％ .

[0141] Step 28: Consult the atlas of water resources investigation and evaluation results in the area (multi-year average annual precipitation contour map, multi-year average annual precipitation coefficient of variation Cv contour map, multi-year average annual runoff depth contour map, multi-year average annual runoff depth coefficient of variation Cv contour map) to obtain the multi-year average precipitation at the center of the catchment area, the multi-year average annual precipitation coefficient of variation Cv value, the multi-year average annual runoff depth, and the multi-year average annual runoff depth coefficient of variation Cv value.

[0142] Step 29: Referring to the above Pearson III curve function algorithm, the annual precipitation P and the corresponding annual runoff depth R at the center of the catchment area under a given guarantee rate N% (cumulative frequency) can be calculated. Figure 4 As shown, based on the principle of the same frequency of precipitation and runoff in a small watershed, the runoff coefficient θ is calculated N％ .

[0143] θ N％ =R N％ / P N％ ;

[0144] Step 210: Calculate the monthly flow process through the monthly precipitation process of the i-th year.

[0145] 10-1: Calculate the monthly distribution ratio of precipitation within a year (i.e., the monthly distribution ratio of the first year in the embodiment of the present application);

[0146] 10-2: Based on the precipitation P in the i-th year, the guarantee rate N% for the i-th year is calculated by the Pearson III curve, and then the annual runoff depth R with the corresponding guarantee rate N% is calculated according to step 9, so as to calculate the runoff coefficient θ for the i-th year.

[0147] 10-3: Calculate the annual runoff Q generated by the precipitation P in the i-th year using the runoff coefficient θ 总 (i.e., the total runoff in the first year in the embodiment of the present application).

[0148] 10-4: Consult the hydrological manual of the basin (region) to obtain the base flow coefficient B; calculate the annual base flow QB = Q 总 ×B (i.e., the first year base flow in the embodiment of the present application), and evenly distributed to the 12 months of the year, i.e., the monthly base flow is QB / 12;

[0149] 10-5: After deducting the annual base flow from the annual runoff, the surface water runoff (i.e. the surface runoff in the first year) is distributed according to the annual distribution ratio of precipitation. The surface water volume is added to the base flow to obtain the monthly runoff in the i-th year.

[0150] Step 211: According to step 210, the monthly runoff (ie, the monthly total runoff) of each year is calculated in sequence.

[0151] Step 212: Select the flow of the driest month in a typical year with a guarantee rate closest to 90%, which is the average flow of the driest month with a 90% guarantee rate (i.e. the average flow of the driest month with a guarantee rate); select the minimum value of the monthly runoff in the past ten years, which is the average flow of the driest month in the past ten years (i.e. the average flow of the driest months in many years).

[0152] In summary, the method provided by the embodiment of the present application includes: obtaining precipitation information and digital elevation model data of relevant rain gauge stations in the basin; determining the annual precipitation and monthly precipitation of the catchment range through the Thiessen polygon method according to the precipitation information and digital elevation model data; fitting the frequency distribution of the annual precipitation through the Pearson curve to determine the first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate; obtaining the multi-year average precipitation and annual runoff characteristic value of the basin center; determining the runoff coefficient under a given guarantee rate based on the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value; determining the monthly total runoff according to the runoff coefficient and the monthly precipitation; determining the low flow flow data according to the monthly total runoff. The embodiment of the present application decomposes the precipitation process through the runoff coefficient and the monthly precipitation, and determines the designed low flow flow through the monthly total runoff, which can design the low flow flow for small watershed areas without data and improve the accuracy of flow design.

[0153] Secondly, refer to the attached Figure 5 A system for determining low-flow flow in a small watershed proposed according to an embodiment of the present invention is described.

[0154] Figure 5 1 is a schematic diagram of the structure of a system for determining low-flow flow in a small watershed according to an embodiment of the present invention, wherein the system specifically comprises:

[0155] The first module 310 is used to obtain precipitation information and digital elevation model data of relevant rain gauge stations in the basin;

[0156] The second module 320 is used to determine the annual precipitation and monthly precipitation of the catchment area by using the Thiessen polygon method according to the precipitation information and the digital elevation model data;

[0157] The third module 330 is used to fit the frequency distribution of the annual precipitation through a Pearson curve to determine a first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate;

[0158] The fourth module 340 is used to obtain the multi-year average precipitation and annual runoff characteristic values ​​of the basin center;

[0159] A fifth module 350 is used to determine a runoff coefficient under a given guarantee rate based on the first model according to the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value;

[0160] The sixth module 360 ​​is used to determine the monthly total runoff according to the runoff coefficient and the monthly precipitation;

[0161] The seventh module 370 is used to determine the low water flow data according to the monthly total runoff.

[0162] It can be seen that the contents of the above method embodiments are all applicable to the present system embodiments, the functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0163] Reference Figure 6 The embodiment of the present invention provides a device for determining low-flow flow in a small watershed, comprising:

[0164] at least one processor 410;

[0165] At least one memory 420, used to store at least one program;

[0166] When the at least one program is executed by the at least one processor 410, the at least one processor 410 implements the method for determining the low water flow of a small watershed.

[0167] Similarly, the contents of the above method embodiments are all applicable to the present device embodiments. The functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0168] An embodiment of the present invention further provides a computer-readable storage medium, in which a program executable by a processor is stored. When the program executable by the processor is executed by the processor, it is used to execute the above-mentioned method for determining the low-flow flow of a small watershed.

[0169] Similarly, the contents of the above method embodiments are all applicable to the present storage medium embodiments. The functions specifically implemented by the present storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0170] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part for which is described as a larger operation is performed independently.

[0171] In addition, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise specified, one or more of the functions and / or features can be integrated into a single physical device and / or software module, or one or more functions and / or features can be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present invention. More specifically, in view of the properties, functions and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional skills of the engineer. Therefore, those skilled in the art can implement the present invention set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0172] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several programs to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0173] The logic and / or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable programs for implementing the logical functions, and may be embodied in any computer-readable medium for use by a program execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch and execute a program from a program execution system, device or apparatus), or in conjunction with such program execution systems, devices or apparatuses. For purposes of this specification, a "computer-readable medium" may be any device that can contain, store, communicate, propagate or transmit a program for use by a program execution system, device or apparatus, or in conjunction with such program execution systems, devices or apparatuses.

[0174] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0175] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable program execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0176] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0177] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0178] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A method for determining low-flow flow in a small watershed, characterized in that: The following steps are involved: Obtain precipitation information and digital elevation model data from relevant rain gauge stations in the basin; According to the precipitation information and the digital elevation model data, the annual precipitation and monthly precipitation of the catchment area are determined by using the Thiessen polygon method; Fitting the frequency distribution of the annual precipitation through a Pearson curve to determine a first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate; Obtain the multi-year average precipitation and annual runoff characteristic values ​​in the basin center; Determine the runoff coefficient under a given guarantee rate based on the first model according to the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value; Determine the monthly total runoff according to the runoff coefficient and the monthly precipitation; Determine low water flow data based on the monthly total runoff; The precipitation information of the relevant rain gauge stations in the basin includes multi-year precipitation information; Determining the monthly total runoff according to the runoff coefficient and the monthly precipitation includes: Obtain annual precipitation information for the first year; the first year is any year among multiple years; Determine the first year's precipitation and the first year's monthly precipitation based on the annual precipitation information; Determine the monthly allocation ratio for the first year based on the precipitation in the first year and the monthly precipitation in the first year; Determine the runoff coefficient for the first year based on the first model according to the precipitation in the first year; Determine the monthly total runoff volume of the first year according to the runoff coefficient of the first year and the monthly allocation ratio of the first year; The first year is updated, and the annual precipitation information of the first year is returned until the monthly total runoff of all years is obtained; the first year after the update is any year that has not been traversed in the multi-year period; Determining the monthly total runoff volume of the first year according to the runoff coefficient of the first year and the monthly allocation ratio of the first year includes: Determine the total runoff volume in the first year based on the runoff coefficient and the catchment area in the first year; Obtaining a base flow coefficient, and determining the base flow in the first year according to the total runoff in the first year and the base flow coefficient; Evenly distribute the first year's base flow to each month to determine the first year's monthly base flow; Determine the surface runoff in the first year according to the total runoff in the first year and the base flow in the first year; Allocate the surface runoff volume of the first year to each month according to the monthly allocation ratio of the first year to determine the monthly surface runoff volume of the first year; The total monthly runoff in the first year is determined according to the monthly base flow in the first year and the monthly surface runoff in the first year.

2. The method for determining low-flow flow in a small watershed according to claim 1, characterized in that: Determining the annual precipitation and monthly precipitation of the catchment area by using the Thiessen polygon method based on the precipitation information and the digital elevation model data includes: The area weight of each rainfall station is determined by the Thiessen polygon method; Determine the monthly precipitation of the catchment area according to the monthly precipitation of each rain gauge station and the area weight; The annual precipitation of the catchment area is determined according to the annual precipitation of each rain gauge station and the area weight.

3. The method for determining low-flow flow in a small watershed according to claim 2, characterized in that: The area weight of each rainfall station is determined by the Thiessen polygon method, including: Determining a catchment area based on the digital elevation model data; Adding the areas of all the points to be estimated within the catchment area and adjacent to the first rainfall station to obtain a first area; An area weight of the first rain gauge is determined according to the first area and the catchment area.

4. The method for determining low-flow flow in a small watershed according to claim 1, characterized in that: The step of determining the runoff coefficient for the first year based on the first model according to the precipitation in the first year includes: Determining a first-year guarantee rate according to the first-year precipitation and based on the first model; According to the first year guarantee rate and based on the first model, determining the first year runoff depth; Based on the principle of the same frequency of precipitation and runoff in a small watershed, the runoff coefficient for the first year is determined according to the runoff depth and the precipitation in the first year.

5. The method for determining low-flow flow in a small watershed according to claim 4, characterized in that: Determining low water flow data according to the monthly total runoff includes: Determine the minimum value of the monthly total runoff as the average flow rate of the driest month over many years; the low water flow data includes the average flow rate of the driest month over many years; or, Determine the distance set between the annual guarantee rate and the preset guarantee rate; Determine the second year corresponding to the minimum distance in the distance set; The minimum value of the total monthly runoff in the second year is determined as the average flow of the driest month with a guaranteed rate; the low water flow data includes the average flow of the driest month with a guaranteed rate.

6. A system for determining low-flow flow in a small watershed, characterized in that: include: The first module is used to obtain precipitation information and digital elevation model data of relevant rain gauge stations in the basin; The second module is used to determine the annual precipitation and monthly precipitation of the catchment area by using the Thiessen polygon method according to the precipitation information and the digital elevation model data; The third module is used to fit the frequency distribution of the annual precipitation through the Pearson curve to determine the first model; the first model is used to determine the annual precipitation and annual runoff depth under a given guarantee rate; The fourth module is used to obtain the multi-year average precipitation and annual runoff characteristic values ​​in the basin center; A fifth module is used to determine the runoff coefficient under a given guarantee rate based on the first model according to the annual precipitation, the multi-year average precipitation and the annual runoff characteristic value; The sixth module is used to determine the monthly total runoff according to the runoff coefficient and the monthly precipitation; The seventh module is used to determine the low water flow data according to the monthly total runoff; The precipitation information of the relevant rain gauge stations in the basin includes multi-year precipitation information. The sixth module is used for: Obtain annual precipitation information for the first year; the first year is any year among multiple years; Determine the first year's precipitation and the first year's monthly precipitation based on the annual precipitation information; Determine the monthly allocation ratio for the first year based on the precipitation in the first year and the monthly precipitation in the first year; Determine the runoff coefficient for the first year based on the first model according to the precipitation in the first year; Determine the monthly total runoff volume of the first year according to the runoff coefficient of the first year and the monthly allocation ratio of the first year; The first year is updated, and the annual precipitation information of the first year is returned until the monthly total runoff of all years is obtained; the first year after the update is any year that has not been traversed in the multi-year period; The sixth module is for: Determine the total runoff volume in the first year based on the runoff coefficient and the catchment area in the first year; Obtaining a base flow coefficient, and determining the base flow in the first year according to the total runoff in the first year and the base flow coefficient; Evenly distribute the first year's base flow to each month to determine the first year's monthly base flow; Determine the surface runoff in the first year according to the total runoff in the first year and the base flow in the first year; Allocate the surface runoff volume of the first year to each month according to the monthly allocation ratio of the first year to determine the monthly surface runoff volume of the first year; The total monthly runoff in the first year is determined according to the monthly base flow in the first year and the monthly surface runoff in the first year.

7. A device for determining low-flow flow in a small watershed, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method for determining the low water flow rate of a small watershed as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing a program executable by a processor, characterized in that: The program executable by the processor is used to implement the method for determining the low water flow rate of a small watershed as described in any one of claims 1 to 5 when executed by the processor.

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