Drainage basin space area rainfall calculation method and device and medium

Abstract

The invention discloses a drainage basin space surface rainfall calculation method and device and a medium. The method comprises the steps that the pixel area of each reflectivity unit of the elevation angle of the lowest layer of a weather radar in a set space range above a drainage basin is calculated; calculating a radar lowest layer elevation angle reflectivity space area; calculating the projection area of the elevation reflectivity space area of the lowest layer of the radar to the watershed range; according to the spatial multi-layer all radar reflectivity unit intensity values, calculating spatial multi-layer all radar reflectivity unit rainfall intensity by using a radar quantitative rainfall estimation relational expression; calculating precipitation per unit time; calculating the total amount of spatial precipitation in the T time period; and calculating the drainage basin space surface rainfall in the T time period according to the total space rainfall in the T time period, the projection area of the radar lowest layer elevation angle reflectivity space area to the drainage basin range and the drainage basin geographic area. The method solves the problems of no data area, rainfall station density and the like of the traditional area rainfall, and improves the time precision, the space precision and the rainfall distribution precision of the area rainfall of the watershed.

Description

Technical Field

[0001] The present invention relates to the technical fields of weather radar, water conservancy and river basin, and more specifically to a method, device and medium for calculating spatial surface rainfall in a river basin. Background Art

[0002] Areal rainfall refers to the average precipitation in a specific region or river basin, defined as the amount of precipitation per unit area. It is a crucial parameter for flood control and reservoir scheduling. A key basis for flood control and flood mitigation decisions is changes in water levels and flow rates. The flow rate of a river basin, the flood mitigation capacity of rivers, and the flood storage capacity of reservoirs are all closely related to the areal rainfall in the basin. Therefore, calculating and forecasting areal rainfall can better inform decisions on flood control and reservoir management by governments at all levels. It can also provide crucial parameters for flood forecasting by water conservancy departments, making it a crucial tool for meteorological and water conservancy departments to serve disaster prevention and mitigation, as well as economic development.

[0003] Weather radar is a primary tool for monitoring and providing early warning of severe convective weather, offering high spatial and temporal resolution for precipitation observations. Weather radar boasts long detection range, high spatial resolution, and the ability to obtain timely precipitation data over large areas. This significantly improves the spatial distribution of precipitation compared to ground-based point rain gauges. Conventional parabolic weather radars have a temporal resolution of minutes, while phased array weather radars offer even higher resolutions, reaching seconds.

[0004] The problems existing in the existing technology are as follows: there are large errors in calculating basin surface rainfall using ground rain gauges, such as: there are areas without rain gauges within the basin, cross-watershed problems in the basin, rain gauge density problems, basin precipitation intensity distribution problems, deviation of the precipitation intensity center, or the absence of obvious rainfall intensity distribution. Summary of the Invention

[0005] The present invention is provided to solve the above-mentioned problems existing in the prior art. Therefore, a spatial surface rainfall calculation method, device, and medium are needed to realize the calculation of spatial surface rainfall in a watershed using weather radar multi-layer reflectivity. The method extracts the weather radar multi-layer reflectivity Z within a set spatial range based on the geographical watershed area, performs data quality control (removes non-precipitation meteorological echoes), calculates the pixel area of ​​the radar lowest layer elevation reflectivity unit, calculates the spatial area of ​​the radar lowest layer elevation reflectivity, calculates the projected area of ​​the radar lowest layer elevation reflectivity spatial area, determines the size of the Z value of all elevation layer reflectivity units within the set spatial range, and uses the reflectivity Z to calculate the reflectivity factor Z. e , according to the radar quantitative precipitation estimation relationship Z e-I calculates the precipitation intensity I for each combined reflectivity unit, calculates the precipitation amount q per unit time t, and then accumulates it over a period of time T to obtain the total spatial precipitation amount Q. The ratio of the total spatial precipitation amount Q to the projected area S of the spatial area of ​​the radar's lowest layer elevation reflectivity, or the basin's geographic area, is the basin's spatial surface rainfall. A method, device, and medium for calculating basin spatial surface rainfall have been invented.

[0006] According to a first aspect of the present invention, a method for calculating spatial surface rainfall in a watershed is provided, the method comprising: Calculate the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar based on the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of radar detection, and the radar beamwidth; The spatial area of ​​radar lowest elevation reflectivity is calculated based on the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar; Calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed; According to the intensity values ​​of all radar reflectivity units in multiple spatial layers, the precipitation intensity of all radar reflectivity units in multiple spatial layers is calculated using the radar quantitative precipitation estimation relationship; Calculate the precipitation per unit time based on the precipitation intensity of all radar reflectivity units in multiple spatial layers; Calculated based on precipitation per unit time T The total amount of spatial precipitation during the time period; according to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial surface rainfall of the watershed within a time period.

[0007] Furthermore, the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar is calculated according to the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of radar detection, and the radar beamwidth using the following formula: (1) Where: is the pixel area of ​​each reflectivity unit at the lowest elevation angle, is the distance between each reflectivity unit and the weather radar at the lowest elevation angle, is the range resolution of radar detection, is the radar beam width, and n is the number of elevation reflectivity units in the lowest layer of the radar.

[0008] Furthermore, the radar lowest elevation reflectivity spatial area is calculated based on the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar using the following formula: (2) Where: is the number of elevation reflectivity units in the lowest layer of the radar, is the pixel area of ​​each reflectivity unit at the lowest elevation angle, S K is the spatial area of ​​the radar's lowest elevation reflectivity.

[0009] Furthermore, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed is calculated using the following formula: (3) Where: is the spatial area of ​​the radar's lowest elevation reflectivity, It is a calculation method for projecting the lowest elevation reflectivity area of ​​the space radar into the watershed.

[0010] Furthermore, the radar quantitative precipitation estimation relationship is expressed as: , the precipitation intensity of all radar reflectivity units in multiple spatial layers is calculated using the following formula: (4) (5) Where: is the radar reflectivity unit intensity value, A and b are coefficients, is the precipitation intensity in the radar reflectivity unit, is the reflectivity factor corresponding to the intensity of the radar reflectivity unit, is the number of spatial multi-layer radar reflectivity units.

[0011] Furthermore, the precipitation per unit time is calculated based on the precipitation intensity of all radar reflectivity units in multiple spatial layers, including: The sum of all precipitation intensities within the spatial range is taken as the precipitation per unit time, and the calculation formula is: (6) Where: Unit time The spatial precipitation is the precipitation intensity of all radar reflectivity units in multiple spatial layers, is the total number of radar reflectivity units in multiple spatial layers, is the temporal resolution of radar detection.

[0012] Furthermore, the precipitation per unit time is calculated T The total amount of spatial precipitation over the time period, including: Precipitation per unit time The time integral of Total spatial precipitation within the time period , the calculation formula is: (7) Where: is the precipitation intensity of the unit reflectivity, for The number of all radar reflectivity units in multiple layers within the time period, is the time resolution of radar detection, The duration of precipitation.

[0013] Further, according to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial rainfall of the watershed within the time period includes: Calculated by the following formula Basin spatial surface rainfall within a time period : (8) Where: for The spatial rainfall of the watershed within the time period, for The total spatial precipitation within the time period, is the projection area of ​​the radar lowest layer elevation reflectivity space within the watershed, is the geographical area of ​​the basin; when When the radar is at the lowest layer, the spatial area of ​​the elevation reflectivity is used to calculate the spatial rainfall of the basin. when When calculating the spatial rainfall of a watershed, the geographical watershed area is used.

[0014] According to a second aspect of the present invention, there is provided a device for calculating spatial surface rainfall in a watershed, the device comprising: The first calculation module is configured to calculate the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar according to the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of the radar detection, and the radar beam width; The second calculation module is configured to calculate the radar lowest layer elevation reflectivity spatial area according to the pixel area of ​​each reflectivity unit of the weather radar lowest layer elevation angle; The third calculation module is configured to calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed; A fourth calculation module is configured to calculate the precipitation intensity of all radar reflectivity units in the spatial multi-layer according to the intensity values ​​of all radar reflectivity units in the spatial multi-layer using a radar quantitative precipitation estimation relationship; A fifth calculation module is configured to calculate the precipitation per unit time based on the precipitation intensity of all radar reflectivity units in the spatial multi-layer; The sixth calculation module is configured to calculate the precipitation per unit time T The total amount of spatial precipitation during the time period; The seventh computing module is configured to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial surface rainfall of the watershed within a time period.

[0015] According to a third aspect of the present invention, a readable storage medium is provided, wherein the readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the method described above.

[0016] The present invention has at least the following beneficial effects: 1. The present invention can improve the temporal resolution and spatial resolution of basin surface rainfall calculation, and can solve the problems of data-free areas in the basin, cross-watershed problems in the basin, density of rain gauges, precipitation intensity distribution in the basin, deviation of precipitation intensity center or the absence of obvious precipitation intensity distribution. It can improve the temporal accuracy, spatial accuracy and spatial distribution accuracy of basin surface rainfall calculation.

[0017] 2. The present invention can advance the timeline of flood peak, flood forecast and prediction, and flash flood disaster warning in the basin, increase the length of flood peak, flood forecast and prediction flood prevention services, and flash flood disaster warning emergency response time, and improve the actual work efficiency of disaster prevention and relief. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram showing the principle of a method for calculating spatial surface rainfall in a watershed according to an embodiment of the present invention is shown.

[0019] Figure 2 A flow chart of a method for calculating spatial surface rainfall in a watershed according to an embodiment of the present invention is shown.

[0020] Figure 3 The figure shows a structural diagram of a basin spatial surface rainfall calculation device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments, but are not intended to limit the present invention. For the various steps described herein, if there is no necessity for a contextual relationship between each other, the order in which they are described as examples herein should not be regarded as limiting, and those skilled in the art should know that they can be adjusted in order as long as the logic between them is not destroyed, resulting in the inability to implement the entire process.

[0022] Figure 1 The schematic diagram of the principle of a method for calculating spatial surface rainfall in a watershed according to an embodiment of the present invention is shown. The embodiment of the present invention provides a method for calculating spatial surface rainfall in a watershed. Figure 1 As shown in Figure 2, this method needs to be applied to the existing weather radar system when it is implemented. Figure 1 The figure shows the multiple layers of radar reflectivity units corresponding to the weather radar system. Each layer of radar reflectivity units corresponds to a radar reflectivity unit area projection. The figure shows the first layer of radar reflectivity units, the second layer of radar reflectivity units, the third layer of radar reflectivity units, the nth layer of radar reflectivity units, and the corresponding radar reflectivity unit spatial areas and geographical basin areas of each layer. The first layer of radar reflectivity units is the lowest layer of elevation radar reflectivity units, which corresponds to the lowest layer of elevation radar reflectivity unit spatial area.

[0023] based on Figure 1 The schematic diagram of the principle of this method shows that the ratio of the spatial precipitation estimated by radar reflectivity to the spatial area projection of the radar reflectivity or the geographic area of ​​the watershed is defined as the spatial surface rainfall of the watershed. The weather radar multi-layer reflectivity can be the multi-layer reflectivity of different elevation layers of a single radar or the multi-layer reflectivity fused from different elevation layers of multiple radars. This embodiment uses the reflectivity of weather radar at different detection elevation angles. The space detected by the radar above the set geographic watershed area is fixed, and the corresponding set radar detection space contains multiple layers of reflectivity. That is, the total spatial precipitation corresponding to the set geographic watershed area is composed of the reflectivity at different radar detection elevation angles. Due to different radar elevation angles, the reflectivity area corresponding to each elevation layer is different, and the area of ​​each reflectivity pixel unit in each elevation layer is also different. This embodiment first calculates the total spatial precipitation of the multi-layer radar reflectivity and then divides it by the projected area of ​​the spatial area of ​​the radar reflectivity at the lowest elevation layer or the geographic area of ​​the watershed to obtain the spatial surface rainfall of the watershed.

[0024] Figure 2 FIG. 4 shows a flow chart of a method for calculating spatial surface rainfall in a watershed according to an embodiment of the present invention. Figure 2 As shown, the method includes steps S100-S700, which are described in detail as follows.

[0025] Set the basin geographical area to The geographical area of ​​the basin can be the entire basin area or the sub-basin area. The distance resolution of weather radar detection is , the radar beam width is , the time resolution of radar detection is The area of ​​the radar lowest layer elevation reflectivity space corresponding to the set space above the basin is , set the number of radar multi-layer reflectivity units in the space to , the distance between each reflectivity unit and the weather radar at the lowest elevation angle of the radar is , the radar lowest layer elevation reflectivity space area The projected area into the basin is , the spatial rainfall in the basin is .

[0026] Step S100 , calculating the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar according to the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of the radar detection, and the radar beam width.

[0027] Specifically, the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar is calculated The formula is: (1) Where: is the pixel area of ​​each reflectivity unit at the lowest elevation angle (unit: square meters 2 ), is the distance between each reflectivity unit and the weather radar at the lowest elevation angle (unit: m), is the range resolution of radar detection (unit: meter), is the radar beamwidth (unit: degree), and n is the number of elevation reflectivity units in the lowest layer of the radar.

[0028] Step S200 , calculating the radar lowest elevation reflectivity spatial area according to the pixel area of ​​each reflectivity unit of the weather radar lowest elevation angle.

[0029] Specifically, calculate the radar lowest layer elevation reflectivity spatial area The formula is: (2) Where: is the number of elevation reflectivity units in the lowest layer of the radar.

[0030] Step S300: Calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area onto the watershed.

[0031] Specifically, calculate the radar lowest layer elevation reflectivity spatial area Projected area within the watershed The formula is: (3) Where: is the spatial area of ​​the lowest layer elevation reflectivity of the radar (unit: square meters m 2 ), It is a calculation method for projecting the lowest elevation reflectivity area of ​​the space radar into the watershed.

[0032] Step S400 , based on the intensity value of each radar reflectivity unit of the spatial multi-layer all radar reflectivities, the precipitation intensity of the spatial multi-layer all radar reflectivities is calculated using a radar quantitative precipitation estimation relationship.

[0033] Specifically, determine the intensity values ​​of all radar reflectivity units in multiple layers of space The size of the radar quantitative precipitation is estimated using the following relationship: , calculate the precipitation intensity of all radar reflectivity units in multiple spatial layers : (4) (5) In formulas (4) and (5): is the radar reflectivity unit intensity value (unit: dBZ), A and b are coefficients, is the precipitation intensity in radar reflectivity units (unit: mm), The reflectivity factor corresponding to the intensity of the radar reflectivity unit (unit: mm 6 / m 3 ), is the total number of radar reflectivity units in multiple layers.

[0034] Step S500 : calculating the precipitation per unit time according to the precipitation intensity of all radar reflectivity units in multiple spatial layers.

[0035] Specifically, the unit time Precipitation is the sum of all precipitation intensities within the spatial range, and the calculation formula is: (6) Where: Unit time Spatial precipitation (unit: mm), is the precipitation intensity of all radar reflectivity units in multiple spatial layers (unit: mm), is the total number of radar reflectivity units in multiple spatial layers, is the temporal resolution of radar detection.

[0036] Step S600, calculate the rainfall per unit time T The total amount of spatial precipitation during the time period.

[0037] Specifically, Total spatial precipitation within the time period is the precipitation per unit time The time integral of is calculated as: (7) Where: is the precipitation intensity of the unit reflectivity (unit: mm), is the number of all radar reflectivity units in multiple layers within the time period t, is the time resolution of radar detection, The duration of precipitation.

[0038] Step S700, according to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial surface rainfall of the watershed within a time period.

[0039] Specifically, Basin spatial surface rainfall within a time period The calculation formula is: (8) Where: The spatial rainfall of the basin (unit: mm / m 2 ), for The total spatial precipitation in the time period (unit: mm), is the projection area of ​​the radar's lowest elevation reflectivity space (unit: square meters m 2 ), is the geographical area of ​​the basin (unit: square meters 2 ). When the radar is at the lowest layer, the projection area of ​​the elevation reflectivity spatial area is used to calculate the spatial rainfall of the basin. When calculating the spatial rainfall of a watershed, the geographical area of ​​the watershed is used.

[0040] The embodiment of the present invention also provides a basin spatial surface rainfall calculation device, such as Figure 3 As shown, the device 300 includes: The first calculation module 301 is configured to calculate the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar based on the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of the radar detection, and the radar beam width; The second calculation module 302 is configured to calculate the radar lowest layer elevation reflectivity spatial area based on the pixel area of ​​each reflectivity unit of the weather radar lowest layer elevation angle; The third calculation module 303 is configured to calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed; The fourth calculation module 304 is configured to calculate the precipitation intensity of all radar reflectivity units in the spatial multi-layer according to the intensity values ​​of all radar reflectivity units in the spatial multi-layer using the radar quantitative precipitation estimation relationship; A fifth calculation module 305 is configured to calculate the precipitation per unit time based on the precipitation intensity of all radar reflectivity units in multiple spatial layers; The sixth calculation module 306 is configured to calculate the precipitation per unit time T The total amount of spatial precipitation during the time period; The seventh calculation module 307 is configured to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial surface rainfall of the watershed within a time period.

[0041] In some embodiments, the first calculation module is further configured to calculate the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar according to the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of radar detection, and the radar beamwidth using the following formula: (1) Where: is the pixel area of ​​each reflectivity unit at the lowest elevation angle, is the distance between each reflectivity unit and the weather radar at the lowest elevation angle, is the range resolution of radar detection, is the radar beam width, and n is the number of elevation reflectivity units in the lowest layer of the radar.

[0042] In some embodiments, the second calculation module is further configured to calculate the radar lowest layer elevation reflectivity spatial area according to the pixel area of ​​each reflectivity unit of the weather radar lowest layer elevation angle by the following formula: (2) Where: is the number of elevation reflectivity units in the lowest layer of the radar, is the pixel area of ​​each reflectivity unit at the lowest elevation angle, S K is the spatial area of ​​the radar's lowest elevation reflectivity.

[0043] In some embodiments, the third calculation module is further configured to calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed using the following formula: (3) Where: is the spatial area of ​​the radar's lowest elevation reflectivity, It is a calculation method for projecting the lowest elevation reflectivity area of ​​the space radar into the watershed.

[0044] In some embodiments, the radar quantitative precipitation estimation relationship is expressed as: The fourth calculation module is further configured to calculate the precipitation intensity of all radar reflectivity units in multiple spatial layers using the following formula: (4) (5) Where: is the radar reflectivity unit intensity value, A and b are coefficients, is the precipitation intensity in the radar reflectivity unit, is the reflectivity factor corresponding to the intensity of the radar reflectivity unit, is the number of spatial multi-layer radar reflectivity units.

[0045] In some embodiments, the fifth computing module is further configured to: The sum of all precipitation intensities within the spatial range is taken as the precipitation per unit time, and the calculation formula is: (6) Where: Unit time The spatial precipitation is the precipitation intensity of all radar reflectivity units in multiple spatial layers, is the total number of radar reflectivity units in multiple spatial layers, is the temporal resolution of radar detection.

[0046] In some embodiments, the sixth computing module is further configured to: Precipitation per unit time The time integral of Total spatial precipitation within the time period , the calculation formula is: (7) Where: is the precipitation intensity of the unit reflectivity, is the number of all radar reflectivity units in multiple layers within the time period t, is the time resolution of radar detection, The duration of precipitation.

[0047] In some embodiments, the seventh computing module is further configured to: Calculated by the following formula Basin spatial surface rainfall within a time period : (8) Where: for The spatial rainfall of the watershed within the time period, for The total spatial precipitation within the time period, is the projection of the radar lowest layer elevation reflectivity spatial area within the watershed, is the geographical area of ​​the basin; when When the radar is at the lowest layer, the spatial area of ​​the elevation reflectivity is used to calculate the spatial rainfall of the basin. when When calculating the spatial rainfall of a watershed, the geographical area of ​​the watershed is used.

[0048] The structure and the method described above belong to the same technical concept and achieve the same technical effect through the same principle, so they will not be described in detail here.

[0049] An embodiment of the present invention further provides a readable storage medium, which 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 of the above embodiments.

[0050] Furthermore, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present invention with equivalent elements, modifications, omissions, combinations (e.g., cross-cutting schemes of various embodiments), adaptations, or changes. The elements of the claims are to be interpreted broadly based on the language employed in the claims and are not limited to the examples described in this specification or during the prosecution of this application, which examples are to be construed as non-exclusive. Therefore, it is intended that the specification and examples be considered as examples only, with the true scope and spirit being indicated by the following claims and their full scope of equivalents.

[0051] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more versions thereof) may be used in combination with each other. For example, a person of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above detailed description, various features may be grouped together to simplify the invention. This should not be interpreted as an intention that a feature of an unclaimed invention is essential to any claim. On the contrary, the subject matter of the present invention may have less than all the features of an embodiment of a particular invention. Therefore, the following claims are incorporated into the detailed description as examples or embodiments, with each claim independently serving as a separate embodiment, and it is contemplated that these embodiments may be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims and the full scope of equivalents to which such claims are entitled.

Claims

1. A method for calculating spatial surface rainfall in a watershed, characterized in that: The method comprises: Calculate the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar based on the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of radar detection, and the radar beamwidth; The spatial area of ​​radar lowest elevation reflectivity is calculated based on the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar; Calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed; According to the intensity values ​​of all radar reflectivity units in multiple spatial layers, the precipitation intensity of all radar reflectivity units in multiple spatial layers is calculated using the radar quantitative precipitation estimation relationship; Calculate the precipitation per unit time based on the precipitation intensity of all radar reflectivity units in multiple spatial layers; Calculated based on precipitation per unit time T The total amount of spatial precipitation during the time period; according to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial surface rainfall of the watershed within a time period.

2. The method according to claim 1, characterized in that The pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar is calculated using the following formula based on the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of radar detection, and the radar beamwidth: （1） Where: is the pixel area of ​​each reflectivity unit at the lowest elevation angle of the radar, is the distance between each reflectivity unit and the weather radar at the lowest elevation angle, is the range resolution of radar detection, is the radar beam width, and n is the number of elevation reflectivity units in the lowest layer of the radar.

3. The method according to claim 1, characterized in that The radar lowest elevation reflectivity spatial area is calculated based on the pixel area of ​​each reflectivity unit at the lowest elevation of the weather radar using the following formula: （2） Where: is the number of elevation reflectivity units in the lowest layer of the radar, is the pixel area of ​​each reflectivity unit at the lowest elevation angle, is the spatial area of ​​the radar's lowest elevation reflectivity.

4. The method according to claim 1, wherein The projection area of ​​the radar's lowest layer elevation reflectivity spatial area onto the watershed is calculated using the following formula: （3） Where: is the spatial area of ​​the radar's lowest elevation reflectivity, It is a calculation method for projecting the lowest elevation reflectivity area of ​​the space radar into the watershed.

5. The method according to claim 1, wherein The radar quantitative precipitation estimation relationship is expressed as: , the precipitation intensity of all radar reflectivity units in multiple spatial layers is calculated using the following formula: （4） （5） Where: is the radar reflectivity unit intensity value, A and b are coefficients, is the precipitation intensity in the radar reflectivity unit, is the reflectivity factor corresponding to the radar reflectivity unit intensity, is the number of multi-layer radar reflectivity units.

6. The method according to claim 1, characterized in that The precipitation per unit time is calculated based on the precipitation intensity of all radar reflectivity units in multiple spatial layers, including: The sum of all precipitation intensities within the spatial range is taken as the precipitation per unit time, and the calculation formula is: （6） Where: Unit time The spatial precipitation is the precipitation intensity of all radar reflectivity units in multiple spatial layers, is the total number of radar reflectivity units in multiple spatial layers, is the temporal resolution of radar detection.

7. The method according to claim 1, characterized in that Calculated based on precipitation per unit time T The total amount of spatial precipitation over the time period, including: Precipitation per unit time The time integral of Total spatial precipitation within the time period , the calculation formula is: （7） Where: is the precipitation intensity of the unit reflectivity, is the number of all radar reflectivity units in multiple layers within the time period t, is the time resolution of radar detection, The duration of precipitation.

8. The method according to claim 1, characterized in that according to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial rainfall of the watershed within the time period includes: Calculated by the following formula Basin spatial surface rainfall within a time period : （8） Where: for The spatial rainfall of the watershed within the time period, for The total spatial precipitation within the time period, is the projection area of ​​the radar lowest layer elevation reflectivity space within the watershed, is the geographical area of ​​the basin; when When the radar is used, the projection area of ​​the lowest layer elevation reflectivity space within the basin is used. To calculate the spatial surface rainfall of the watershed; when When using the basin's geographic area Calculate the spatial surface rainfall of the watershed.

9. A basin spatial surface rainfall calculation device, characterized in that: The device comprises: The first calculation module is configured to calculate the pixel area of ​​each reflectivity unit at the lowest elevation angle of the weather radar according to the distance between each reflectivity unit at the lowest elevation angle and the weather radar, the range resolution of the radar detection, and the radar beam width; The second calculation module is configured to calculate the radar lowest layer elevation reflectivity spatial area according to the pixel area of ​​each reflectivity unit of the weather radar lowest layer elevation angle; The third calculation module is configured to calculate the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the watershed; A fourth calculation module is configured to calculate the precipitation intensity of all radar reflectivity units in the spatial multi-layer according to the intensity values ​​of all radar reflectivity units in the spatial multi-layer using a radar quantitative precipitation estimation relationship; A fifth calculation module is configured to calculate the rainfall per unit time based on the precipitation intensity of all radar reflectivity units in the spatial multi-layer; The sixth calculation module is configured to calculate the rainfall per unit time T The total amount of spatial precipitation during the time period; The seventh computing module is configured to T The total spatial precipitation within the time period, the projection area of ​​the radar lowest layer elevation reflectivity spatial area into the basin, and the calculation of the basin's geographical area T The spatial surface rainfall of the watershed within a time period. 10 . A non-transitory computer-readable storage medium storing instructions, which, when executed by a processor, perform the method according to claim 1 .

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