Method and device for calculating drainage basin space surface rainfall by using radar combined reflectivity, and medium

Abstract

The invention discloses a method and a device for calculating drainage basin space surface rainfall by using radar combined reflectivity, and a medium. The method comprises the following steps: calculating a radar combined reflectivity space area in a set range over a drainage basin; calculating the projection area of the radar combined reflectivity space area in the watershed range; according to the intensity value of each radar combined reflectivity unit in the spatial range corresponding to the projection area, calculating the rainfall intensity of each radar combined reflectivity unit by using a radar quantitative rainfall estimation relation; calculating precipitation qt in unit time t; calculating the total space rainfall amount of the time period; according to the total space rainfall amount of the time period, the projection of the radar combined reflectivity space area and the drainage basin geographic area, the drainage basin space surface rainfall in the T time period is calculated. The problems of rainfall intensity distribution and rainfall intensity center distribution of traditional area rainfall are solved, and the time precision, the space precision and the rainfall distribution precision of the area rainfall of the drainage basin are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of weather radar, water conservancy, river basin, and more particularly to a method and device for calculating basin spatial area rainfall using radar combined reflectivity, and a medium. BACKGROUND

[0002] Area rainfall refers to the average precipitation condition of a specific region or basin, defined as the precipitation on a unit area, which is a very important parameter in flood control and flood fighting and reservoir regulation. An important basis for flood control and flood fighting decision is the change of water level and flow, and the flow of the basin, the flood control capacity of the river and the flood storage capacity of the reservoir are closely related to the area rainfall of the basin, so the development of area rainfall calculation and area rainfall forecast can better provide an important basis for the decision of government at all levels to organize flood control and flood fighting and reservoirs, and can also provide a very important parameter for the flood forecast of the water conservancy department, which is an important means for the meteorological department and the water conservancy department to serve the disaster prevention and disaster relief and economic construction. The traditional use of ground point rainfall station to calculate the area rainfall of the basin compares the ground rainfall with the geographical area of the basin, which mainly has the following problems: (1) Cross watershed problem: using the point rainfall station on one side of the watershed as the representative of the part of the area on the other side of the watershed, the calculation of the area rainfall of each sub-basin will bring larger error; (2) Ground point rainfall station distribution problem: due to the uneven distribution of ground point rainfall stations in the basin, the precipitation area may be relatively far away from the position of the ground point rainfall station, so the ground point rainfall station is not representative of the precipitation distribution of the sub-basin; (3) Ground point rainfall station density problem: due to the construction density of ground point rainfall stations, generally only one point rainfall station exists within a range of 50-100km 2 , so the sparseness of ground point rainfall stations leads to low spatial resolution of precipitation observation; (4) No data area: in the mountainous area within the basin, the terrain is large and the landform is complex and diverse, the high mountainous area is uninhabited, and ground point rainfall stations cannot be built in many places, so ground point rainfall precipitation data cannot be directly obtained, and therefore there is a large area of no data area in the basin; (5) Rainfall intensity and distribution problem: due to the unevenness of the distribution of convective precipitation, the use of ground point rainfall station precipitation to calculate the area rainfall of the sub-basin will lead to the deviation of the center of rainfall intensity, or the situation that no obvious rainfall intensity distribution is observed, and most of the rainfall is mixed with convective precipitation.

[0003] (6) Ground point rainfall station measures the precipitation that has fallen to the ground, which has a certain lag on the time scale of flood peak and flood forecast, mountain flood disaster warning, and the emergency response timeline is short, which is not conducive to the development of disaster prevention and relief work.

[0004] Weather radar is a primary tool for monitoring and issuing early warnings of severe convective weather, offering high spatial and temporal resolution for precipitation observation. Weather radar boasts advantages such as long detection range, high spatial resolution, and the ability to acquire large-area precipitation data promptly, providing a significant advantage over ground-based rain gauges in detecting the spatial distribution of precipitation. Conventional parabolic weather radar achieves minute-level temporal resolution, while phased array weather radar offers even higher resolution, reaching second-level.

[0005] This invention provides a method, apparatus, and medium for calculating surface rainfall in a watershed using radar combined reflectivity, to solve at least one of the following technical problems: (1) Solve the problem of areas without data from ground-based rain gauge stations; (2) Solve the problem of insufficient representativeness of ground-based rain gauge stations; (3) Solve the problem of insufficient spatial distribution of precipitation from ground-based rain gauges; (4) To solve the problem of low temporal and spatial resolution of precipitation observation due to the sparseness of ground point rain gauges; (5) To address the problem that ground-based rain gauges have a short timeline for forecasting and predicting basin flood peaks and floods, as well as for early warning of flash floods. Summary of the Invention

[0006] This invention addresses the aforementioned problems in the prior art. Therefore, there is a need for a method, apparatus, and medium for calculating surface rainfall in a watershed using combined radar reflectivity, to realize the calculation of surface rainfall in a watershed using combined weather radar reflectivity and to extract the combined weather radar reflectivity within a certain spatial range above the watershed. Z Data quality control was performed (excluding non-precipitation meteorological echoes), the pixel area of ​​the radar combined reflectivity unit was calculated, the spatial area of ​​the radar combined reflectivity was obtained, the projection of the radar combined reflectivity spatial area over the watershed was calculated, and the combined reflectivity unit within the spatial area corresponding to the projected area was determined. Z The magnitude of the value is determined by the combined reflectance. Z Calculate the reflectivity factor Z e Based on the radar quantitative precipitation estimation formula Z e -I Calculate the precipitation intensity for each combined reflectivity unit. I Calculate the unit time t Rainfall q After a period of time T The accumulation of spatial precipitation Q Total spatial precipitation Q Projection of the reflectivity spatial area in combination with radar over the watershed S The ratio is the watershed surface rainfall.

[0007] According to a first aspect of the present application, there is provided a method for calculating the spatial areal rainfall of a catchment area using radar composite reflectivity, the method comprising: calculating the radar composite reflectivity spatial area within a set range above the catchment area according to the distance resolution and the number of radar composite reflectivity cells ; calculating the radar composite reflectivity spatial area within a set range above the catchment area according to the distance resolution and the number of radar composite reflectivity cells calculating the projection of the radar composite reflectivity spatial area within the catchment area ; calculating the projection of the radar composite reflectivity spatial area within the catchment area according to the projection for each radar composite reflectivity cell intensity value within the corresponding spatial range, calculating the precipitation intensity of each radar composite reflectivity cell using a radar quantitative precipitation estimation relationship; calculating the precipitation amount q per unit time t for each radar composite reflectivity cell according to the precipitation intensity of each radar composite reflectivity cell t ; calculating the spatial precipitation total within a time period t for each radar composite reflectivity cell according to the precipitation amount q per unit time t ; calculating the spatial precipitation total within a time period ; calculating the spatial areal rainfall of the catchment area within a time period according to the spatial precipitation total within a time period , the radar composite reflectivity spatial area within a set range above the catchment area , and the projection of the radar composite reflectivity spatial area within the catchment area . T

[0008] Further, the radar composite reflectivity spatial area within a set range above the catchment area is calculated according to the distance resolution and the number of radar composite reflectivity cells by the following formula : (1) wherein: is the distance resolution, is the number of radar composite reflectivity cells.

[0009] Further, the projection of the radar composite reflectivity spatial area within the catchment area is calculated according to the radar composite reflectivity spatial area within a set range above the catchment area by the following formula : (2) wherein: G is the calculation method of the projection of the radar composite reflectivity spatial area to the ground catchment area. ​​

[0010] Further, the radar quantitative precipitation estimation relationship is expressed as: wherein is the combined reflectivity factor corresponding to the intensity of each radar combined reflectivity unit, A and b are coefficients, is the precipitation intensity of each radar combined reflectivity unit.

[0011] Further, the projection is calculated according to the following formula: The precipitation intensity of each radar combined reflectivity unit is calculated by using the radar quantitative precipitation estimation relationship corresponding to the intensity value of each radar combined reflectivity unit in the spatial range: (3) (4) In the formula: is the intensity value of each radar combined reflectivity unit, A and b are coefficients, is the precipitation intensity of each radar combined reflectivity unit, is the combined reflectivity factor corresponding to the intensity of each radar combined reflectivity unit.

[0012] Further, the precipitation amount q t per unit time is calculated according to the precipitation intensity of each radar combined reflectivity unit: t The precipitation amount per unit time is the sum of all precipitation intensities in the spatial range, and the calculation formula is: (5) In the formula: is the precipitation intensity of the combined reflectivity unit, is the number of radar combined reflectivity units, is the time resolution of radar detection.

[0013] Further, the spatial precipitation total amount t in the time period is calculated according to the precipitation amount q t per unit time: The spatial precipitation total amount in the time period is the time integral of the precipitation amount per unit time , and the calculation formula is: (6) In the formula: is the precipitation intensity of the combined reflectivity unit, is the number of radar combined reflectivity units per unit time t,​​​​​ For radar detection time resolution, This refers to the duration of rainfall.

[0014] Furthermore, according to Total spatial precipitation over a period of time Spatial area of ​​radar combined reflectivity within a set range over the river basin And the projection of the spatial area of ​​radar combined reflectivity within the watershed. calculate T The watershed spatial surface rainfall during the time period includes: Total spatial precipitation Divide by the projection of the radar combined reflectivity spatial area over the watershed. As Spatial rainfall in the watershed during the time period The calculation formula is: (7) In the formula: For watershed spatial surface rainfall, Total spatial precipitation The radar composite reflectivity spatial area is projected onto the watershed area. The geographical area of ​​the basin; when When using radar combined reflectivity spatial area, the projected area within the watershed is considered. Calculate the spatial surface rainfall of the watershed; when When using the geographical area of ​​the watershed Calculate the spatial surface rainfall of the watershed.

[0015] According to a second aspect of the present invention, an apparatus for calculating surface rainfall in a watershed using radar combined reflectivity is provided, the apparatus comprising: The first calculation module is configured to calculate the radar combined reflectivity spatial area within a set range above the watershed based on the range resolution and the number of radar combined reflectivity units. ; The second calculation module is configured to calculate the spatial area of ​​the combined radar reflectivity within a set range above the watershed. Calculate the projection of the combined radar reflectivity spatial area within the watershed. ; The third calculation module is configured to calculate based on the projection. The intensity of precipitation for each radar composite reflectivity unit within the corresponding spatial range is calculated using the radar quantitative precipitation estimation relationship. The fourth calculation module is configured to calculate the precipitation intensity per unit time based on the precipitation intensity of each radar combined reflectivity unit.t precipitation q t ; a fifth calculation module configured to calculate a spatial precipitation total amount in the time period according to the precipitation q t per unit time t in the time period ; a sixth calculation module configured to calculate a spatial surface rainfall in the time period according to the spatial precipitation total amount in the time period , a radar combined reflectivity spatial area in a set range above the basin , and a projection of the radar combined reflectivity spatial area in the basin range T .

[0016] According to a third aspect of the present application, a readable storage medium is provided, the readable storage medium storing one or more programs, the one or more programs being executable by one or more processors to implement the method as described above.

[0017] The present application has at least the following beneficial effects: 1. The present application can improve the time resolution and spatial resolution of the basin surface rainfall calculation, can solve the problems of the un-informed area of the basin, the cross-ridge problem of the basin, the rainfall station density problem, the basin precipitation intensity distribution problem, the precipitation intensity center deviation or the appearance of the non-obvious precipitation intensity distribution, etc., can improve the time accuracy, spatial accuracy and precipitation spatial distribution accuracy of the basin surface rainfall calculation.

[0018] 2. The present application can move the time line of the basin flood peak, flood forecast, mountain flood disaster warning forward, increase the flood peak, flood forecast flood control service, mountain flood disaster warning emergency response time length, and improve the actual work efficiency of disaster prevention and relief. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Fig. 1 shows a schematic diagram of a method for calculating a basin spatial surface rainfall using radar combined reflectivity according to an embodiment of the present application.

[0020] Figure 2 Fig. 2 shows a flowchart of a method for calculating a basin spatial surface rainfall using radar combined reflectivity according to an embodiment of the present application.

[0021] Figure 3 Fig. 3 shows a structure diagram of an apparatus for calculating a basin spatial surface rainfall using radar combined reflectivity according to an embodiment of the present application. DETAILED DESCRIPTION

[0022] ​​​For those skilled in the art to better understand the technical solutions of the present application, the present application will be described in detail below in combination with the drawings and specific embodiments. The embodiments of the present application will be further described in detail below in combination with the drawings and specific embodiments, but not as a limitation to the present application. The order in which each step is described herein as an example should not be considered as a limitation, and those skilled in the art should know that the order can be adjusted as long as the logic between them is not destroyed and the whole process cannot be realized.

[0023] In view of the problems in the prior art, there is a large error in calculating the basin area rainfall using ground rainfall stations, such as: there is no rainfall station area in the basin range, the cross watershed problem of the basin, the rainfall station density problem, the rainfall intensity distribution problem of the basin, the rainfall intensity center deviation or the occurrence of the obvious rainfall intensity distribution condition. The embodiment of the present application provides a method for calculating the basin spatial area rainfall by radar combined reflectivity. As shown in Figure 1 The principle diagram of the method is shown in the figure, and the method needs to be applied to the existing weather radar system in the specific implementation. The radar combined reflectivity unit corresponding to the weather radar system will form a radar combined reflectivity space and a radar combined reflectivity space area projection. In some embodiments, the radar combined reflectivity space area projection can reflect the geographical basin area.

[0024] Based on Figure 1 The principle diagram of the method is shown in the figure, and the method realizes the calculation of the basin spatial area rainfall in the space above the basin by the weather radar combined reflectivity. The weather radar combined reflectivity can be a single radar combined reflectivity or a multi-radar fused combined reflectivity. The weather radar combined reflectivity Z in the set spatial range is extracted, the data quality control (removing non-precipitation meteorological echo) is carried out, the pixel area of the combined reflectivity unit is calculated, the space area of the combined reflectivity is calculated, the projection of the combined reflectivity area is calculated, the size of each combined reflectivity Z value in the corresponding space range of the projection area is determined, and the combined reflectivity factor Z e is calculated by the combined reflectivity Z according to the radar quantitative estimation precipitation relationship Z e -I, the precipitation intensity I of each combined reflectivity unit is calculated, the precipitation q of the unit time t is calculated, and the spatial precipitation total amount Q is calculated after a period of time T accumulation. The ratio of the spatial precipitation total amount Q to the projection S of the radar combined reflectivity space area or the basin geographical area is the basin spatial area rainfall.

[0025] Figure 2 A flow chart of a method for calculating the basin spatial area rainfall by radar combined reflectivity according to an embodiment of the present application is shown in the figure, and the method includes steps S100-S600, which are described in detail as follows. Figure 2 As shown in the figure, the method includes steps S100-S600, which are described in detail as follows.

[0026] The basin geographical area is The basin geographical area can be the whole basin area or a sub-basin area, and the radar combined reflectivity space area in the set range above the basin is The projection of the radar combined reflectivity space area is The distance resolution of the weather radar detection is The time resolution of the radar detection is The pixel area of each radar combined reflectivity unit is The projection The number of radar combined reflectivity units in the corresponding space range is The intensity value of each radar combined reflectivity unit is The basin space surface rainfall is .

[0027] Step S100, according to the distance resolution and the number of radar combined reflectivity units, the radar combined reflectivity space area in the set range above the basin is calculated .

[0028] Specifically, the radar combined reflectivity space area in the set range above the basin is calculated , and the formula is: (1) In the formula: is the distance resolution (unit: m), is the number of radar combined reflectivity units.

[0029] Step S200, according to the radar combined reflectivity space area in the set range above the basin , the projection of the radar combined reflectivity space area in the basin range is calculated .

[0030] Specifically, the projection of the radar combined reflectivity space area in the basin range is calculated , and the formula is: (2) In the formula: is the calculation method of the projection of the radar combined reflectivity space area to the ground basin range.

[0031] Step S300, according to the intensity value of each radar combined reflectivity unit in the space range, the precipitation intensity of each radar combined reflectivity unit is calculated by using the radar quantitative precipitation estimation relationship.

[0032] Specifically, it is judged that the projection corresponds to the intensity value of each radar combined reflectivity unit in the space range The size is estimated using the radar quantitative precipitation estimation formula. Calculate the precipitation intensity for each radar composite reflectivity unit. : (3) (4) In equations (3) and (4): For each radar composite reflectivity element, the intensity value is given (unit: dBZ), where A and b are coefficients. Precipitation intensity (in millimeters, mm) for each radar composite reflectivity unit. Combined reflectivity factor (unit: mm) corresponding to the intensity of each radar combined reflectivity element 6 / m 3 ).

[0033] Step S400: Calculate the precipitation intensity per unit time based on the precipitation intensity of each radar composite reflectivity unit. t Precipitation q t .

[0034] Specifically, per unit time Rainfall The sum of all precipitation intensities within a given spatial range is calculated using the following formula: (5) In the formula: Precipitation intensity (unit: mm) for combined reflectivity units. The number of radar combined reflectivity units. This represents the temporal resolution of radar detection.

[0035] Step S500, based on unit time t Precipitation q t calculate Total spatial precipitation over a period of time .

[0036] Specifically, Total spatial precipitation over a period of time Rainfall per unit time The time integral is calculated using the following formula: (6) In the formula: Precipitation intensity (unit: mm) for combined reflectivity units. The number of radar composite reflectivity elements per unit time t. For radar detection time resolution, This refers to the duration of rainfall.

[0037] Step S600, according to the total amount of spatial precipitation in the time period , the spatial area of radar combined reflectivity in the set range above the basin and the projection of the spatial area of radar combined reflectivity in the basin range is calculated T the spatial surface rainfall of the basin in the time period.

[0038] Specifically, the total amount of spatial precipitation is divided by the projection of the spatial area of radar combined reflectivity in the basin range as the spatial surface rainfall of the basin in the time period , and the calculation formula is: (7) In the formula: is the spatial surface rainfall of the basin, is the total amount of spatial precipitation, is the projected area of the spatial area of radar combined reflectivity in the basin range, is the geographical area of the basin. When , the projected area of the spatial area of radar combined reflectivity in the basin range is used to calculate the spatial surface rainfall of the basin; When , the geographical area of the basin is used to calculate the spatial surface rainfall of the basin.

[0039] The embodiment of the present application also provides a device for calculating the spatial surface rainfall of the basin using radar combined reflectivity, as shown in Figure 3 , the device 300 comprises: a first calculation module 301 configured to calculate the spatial area of radar combined reflectivity in the set range above the basin according to the distance resolution and the number of radar combined reflectivity units ; a second calculation module 302 configured to calculate the projection of the spatial area of radar combined reflectivity in the basin range according to the spatial area of radar combined reflectivity in the set range above the basin ; a third calculation module 303 configured to calculate the precipitation intensity of each radar combined reflectivity unit by using the radar quantitative precipitation estimation relationship according to the intensity value of each radar combined reflectivity unit in the corresponding spatial range of the projection ; a fourth calculation module 304 configured to calculate the precipitation amount q per unit time according to the precipitation intensity of each radar combined reflectivity unit t t ​; The fifth calculation module 305 is configured to calculate based on unit time. t Precipitation q t calculate Total spatial precipitation over a period of time ; The sixth calculation module 306 is configured to, according to Total spatial precipitation over a period of time Spatial area of ​​radar combined reflectivity within a set range over the river basin And the projection of the spatial area of ​​radar combined reflectivity within the watershed. calculate T The spatial surface rainfall of the watershed within a given time period.

[0040] In some embodiments, the first calculation module is further configured to calculate the radar combined reflectivity spatial area within a set range above the watershed using the following formula based on the range resolution and the number of radar combined reflectivity elements. : (1) In the formula: For distance resolution, This represents the number of radar composite reflectivity units.

[0041] In some embodiments, the second calculation module is further configured to calculate the radar combined reflectivity spatial area within a set range above the watershed using the following formula. Calculate the projection of the combined radar reflectivity spatial area within the watershed. : (2) In the formula: G This is a method for calculating the projection of the radar combined reflectivity spatial area onto the ground watershed area.

[0042] In some embodiments, the radar quantitative precipitation estimation relationship is expressed as: ,in The combined reflectivity factor corresponds to the intensity of each radar combined reflectivity unit, where A and b are coefficients. Precipitation intensity for each radar composite reflectivity unit.

[0043] In some embodiments, the third calculation module is further configured to calculate based on the projection using the following formula. For each radar composite reflectivity unit within the corresponding spatial range, the precipitation intensity of each radar composite reflectivity unit is calculated using the radar quantitative precipitation estimation relationship: (3) (4) In the formula: For each radar composite reflectivity unit intensity value, A and b are coefficients. Precipitation intensity for each radar composite reflectivity unit, The combined reflectivity factor corresponding to the intensity of each radar combined reflectivity unit.

[0044] In some embodiments, the fourth computing module is further configured to: unit time Rainfall The sum of all precipitation intensities within a given spatial range is calculated using the following formula: (5) In the formula: For precipitation intensity of combined reflectivity units, The number of radar combined reflectivity units. This represents the temporal resolution of radar detection.

[0045] In some embodiments, the fifth computing module is further configured to: Rainfall per unit time Time integral as Total spatial precipitation over a period of time The calculation formula is: (6) In the formula: For precipitation intensity of combined reflectivity units, The number of radar composite reflectivity elements per unit time t. For radar detection time resolution, This refers to the duration of rainfall.

[0046] In some embodiments, the sixth computing module is further configured to: Total spatial precipitation Divide by the projection of the radar combined reflectivity spatial area over the watershed. As Spatial rainfall in the watershed during the time period The calculation formula is: (7) In the formula: For watershed spatial surface rainfall, Total spatial precipitation The radar composite reflectivity spatial area is projected onto the watershed area. The geographical area of ​​the basin; when When the radar reflectivity is greater than or equal to the threshold value, the projection area of the radar reflectivity space area in the basin range is used The basin spatial surface rainfall is calculated. When the radar reflectivity is greater than or equal to the threshold value, the projection area of the radar reflectivity space area in the basin range is used The basin spatial surface rainfall is calculated. The basin spatial surface rainfall is calculated.

[0047] It should be noted that the various device structures described in the embodiments belong to the same technical concept as the methods described above, and achieve the same technical effects through the same principles, and will not be described here.

[0048] The embodiment of the application further provides a readable storage medium, the readable storage medium stores one or more programs, the one or more programs can be executed by one or more processors to implement the method described in any one of the above embodiments.

[0049] In addition, although the exemplary embodiments have been described herein, the scope of the application includes any and all embodiments having equivalent elements, modifications, omissions, combinations (for example, solutions that cross various embodiments), adaptations, or alterations based on the present disclosure. The elements in the claims are to be construed broadly based on the language adopted by the claims, and are not limited to the examples described in the specification or during the prosecution of the application, which examples are to be construed as non-exclusive. Therefore, the specification and examples are to be considered as merely illustrative of the subject matter of the application, the true scope and spirit being indicated by the full scope of the following claims, and their equivalents.

[0050] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) can be used in combination with each other. Other embodiments can be used in addition to those described above, such as by one of ordinary skill in the art reading the above description. In addition, in the above detailed description, various features can be grouped together in one or more embodiments for simplicity. This should not be interpreted as a requirement that the features be grouped together in one or more embodiments of the application. Rather, the subject matter of the application can be less than all of the features of a particular embodiment. Accordingly, the following claims are hereby incorporated into the detailed description, by way of example or embodiment, in which each claim is independently a separate embodiment, and the embodiments can be combined with each other in various combinations or permutations. The scope of the application should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A method for calculating surface rainfall in a watershed using radar combined reflectivity, characterized in that, The method includes: Calculate the radar combined reflectivity spatial area within a predetermined range over the watershed based on range resolution and the number of radar combined reflectivity elements. ; Based on the radar combined reflectivity spatial area within a predetermined range over the watershed Calculate the projection of the combined radar reflectivity spatial area within the watershed. ; According to projection The intensity of precipitation for each radar composite reflectivity unit within the corresponding spatial range is calculated using the radar quantitative precipitation estimation relationship. Calculate the unit time based on the precipitation intensity of each radar composite reflectivity unit. t Precipitation q t ; According to unit time t Precipitation q t calculate Total spatial precipitation over a period of time ; according to Total spatial precipitation over a period of time Spatial area of ​​radar combined reflectivity within a set range over the river basin And the projection of the spatial area of ​​radar combined reflectivity within the watershed. calculate T The spatial surface rainfall of the watershed within a given time period.

2. The method according to claim 1, characterized in that, The radar composite reflectivity spatial area within a predetermined range over the watershed is calculated using the following formula, based on the range resolution and the number of radar composite reflectivity elements. : （1） In the formula: For distance resolution, This represents the number of radar composite reflectivity units.

3. The method according to claim 1, characterized in that, The following formula is used to determine the spatial area of ​​the combined radar reflectivity within a set range over the watershed. Calculate the projection of the combined radar reflectivity spatial area within the watershed. : （2） In the formula: G This is a method for calculating the projection of the radar combined reflectivity spatial area onto the ground watershed area.

4. The method according to claim 1, characterized in that, The radar quantitative precipitation estimation relationship is expressed as follows: ,in The combined reflectivity factor corresponds to the intensity of each radar combined reflectivity unit, where A and b are coefficients. Precipitation intensity for each radar composite reflectivity unit.

5. The method according to claim 1, characterized in that, Based on the projection using the following formula For each radar composite reflectivity unit within the corresponding spatial range, the precipitation intensity of each radar composite reflectivity unit is calculated using the radar quantitative precipitation estimation relationship: （3） （4） In the formula: For each radar composite reflectivity unit intensity value, A and b are coefficients. Precipitation intensity for each radar composite reflectivity unit, The combined reflectivity factor corresponding to the intensity of each radar combined reflectivity unit.

6. The method according to claim 1, characterized in that, Calculate the unit time based on the precipitation intensity of each radar composite reflectivity unit. t Precipitation q t ,include: unit time Rainfall The sum of all precipitation intensities within a given spatial range is calculated using the following formula: （5） In the formula: For precipitation intensity of combined reflectivity units, The number of radar combined reflectivity units. This represents the temporal resolution of radar detection.

7. The method according to claim 1, characterized in that, According to unit time t Precipitation q t calculate Total spatial precipitation over a period of time ,include: Rainfall per unit time Time integral as Total spatial precipitation over a period of time The calculation formula is: （6） In the formula: For precipitation intensity of combined reflectivity units, The number of radar composite reflectivity elements per unit time t. For radar detection time resolution, This refers to the duration of rainfall.

8. The method according to claim 1, characterized in that, according to Total spatial precipitation over a period of time Spatial area of ​​radar combined reflectivity within a set range over the river basin And the projection of the spatial area of ​​radar combined reflectivity within the watershed. calculate T The watershed spatial surface rainfall during the time period includes: Total spatial precipitation Divide by the projection of the radar combined reflectivity spatial area over the watershed. As Spatial rainfall in the watershed during the time period The calculation formula is: （7） In the formula: For watershed spatial surface rainfall, Total spatial precipitation The radar composite reflectivity spatial area is projected onto the watershed area. The geographical area of ​​the basin; when When using radar combined reflectivity spatial area, the projected area within the watershed is considered. Calculate the spatial surface rainfall of the watershed; when When using the geographical area of ​​the watershed Calculate the spatial surface rainfall of the watershed.

9. A device for calculating surface rainfall in a watershed using radar combined reflectivity, characterized in that, The device includes: The first calculation module is configured to calculate the radar combined reflectivity spatial area within a set range above the watershed based on the range resolution and the number of radar combined reflectivity units. ; The second calculation module is configured to calculate the spatial area of ​​the combined radar reflectivity within a set range above the watershed. Calculate the projection of the combined radar reflectivity spatial area within the watershed. ; The third calculation module is configured to calculate based on the projection. The intensity of precipitation for each radar composite reflectivity unit within the corresponding spatial range is calculated using the radar quantitative precipitation estimation relationship. The fourth calculation module is configured to calculate the precipitation intensity per unit time based on the precipitation intensity of each radar combined reflectivity unit. t Precipitation q t ; The fifth calculation module is configured to calculate based on unit time. t Precipitation q t calculate Total spatial precipitation over a period of time ; The sixth calculation module is configured to, based on Total spatial precipitation over a period of time Spatial area of ​​radar combined reflectivity within a set range over the river basin And the projection of the spatial area of ​​radar combined reflectivity within the watershed. Or calculation of watershed geographical area T The spatial surface rainfall of the watershed within a given time period.

10. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, perform the method according to any one of claims 1 to 8.

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