A flash flood disaster early warning method based on the association between protection objects and rainfall stations

Abstract

The present invention discloses a flash flood disaster warning method based on the association between the protected object and the rainfall station, comprising the following steps: Step 1, classify all the normal flood reporting rainfall stations in the area where the protected object is located according to their relative positions with the protected object; Step 2, calculate the density of rainfall stations in the upstream basin of the protected object, and establish the association between the protected object and the rainfall stations according to the density of rainfall stations; Step 3, construct a flash flood disaster warning method, including single-station warning, surface rainfall warning and multi-station warning; Step 4, collect rainfall data of each rainfall station in the area where the protected object is located in real time, if the observed rainfall of a certain rainfall station exceeds the warning threshold, first determine the type of the rainfall station, and then select the corresponding warning method for warning. The method of the present invention solves the problem that the existing flash flood disaster warning method is difficult to consider the uneven spatial distribution of the disaster-causing rainstorm, and reduces the false alarm rate and missed alarm rate of the flash flood disaster warning.

Description

Technical Field

[0001] The present invention belongs to the technical field of flash flood disaster warning, and in particular relates to a flash flood disaster warning method based on the association mode between a protection object and a rainfall station. Background Art

[0002] Flash flood disasters refer to the floods caused by heavy rainfall in hilly areas and the secondary disasters induced by them. They are characterized by strong suddenness, wide impact range, and great destructive power, which bring huge losses and threats to people's lives and property. Therefore, effective monitoring and early warning of flash flood disasters are important issues in disaster prevention and mitigation.

[0003] In the flash flood disaster monitoring and early warning system, it is necessary to establish an association between the flash flood disaster protection objects (such as villages) and rain gauges. When the observed rainfall at a certain rain gauge exceeds the warning threshold, the flash flood disaster monitoring and early warning system will automatically issue an early warning to the village associated with the rain gauge, reminding relevant personnel to take preventive measures in time to avoid or reduce the impact of flash flood disasters.

[0004] At present, the commonly used association method and early warning method are: the protected object is associated with all the rain stations in its vicinity. If the observed rainfall of one of the rain stations exceeds the rainfall warning threshold, the flash flood disaster monitoring and early warning system will issue an early warning for the protected object. The problems with this association method and early warning method mainly include: ① When heavy rain occurs in the upper reaches of the basin and the rainfall near the protected object located in the lower reaches of the basin does not exceed the rainfall warning threshold, the evolution of the flood to the village may still cause flash flood disasters at the protected object. The existing early warning method is difficult to consider this situation and is prone to miss flash flood disasters; ② When the station density is low, there are some protected objects that have no associated rain stations in the vicinity of the protected object, which is easy to miss the flash flood disasters of the protected object. At present, some studies have tried to increase the associated rain stations in the upper reaches of the basin where the protected object is located on the basis of nearby stations when improving the commonly used methods, but have not improved the early warning method at the same time. The problems with the existing improved methods include: local and short-term heavy rainfall in the upper reaches is difficult to cause flash flood disasters for the downstream protected objects. Only the observed rainfall of one station exceeding the warning threshold is used as the basis for issuing warnings, which is easy to miss flash flood disasters. Summary of the invention

[0005] The purpose of the present invention is to provide a flash flood disaster early warning method based on the association mode between the protection object and the rainfall station, so as to reduce the false alarm rate and the missed alarm rate of the flash flood disaster early warning.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention discloses a flash flood disaster early warning method based on the association mode between the protection object and the rainfall station, and the method comprises the following steps:

[0008] Step 1: Classify the rainfall stations: classify all rainfall stations that normally report floods in the area where the protected object is located according to their relative positions to the protected object;

[0009] Step 2: Establish the association method between the protected object and the rainfall station: calculate the density of rainfall stations in the upstream basin of the protected object, and establish the association method between the protected object and the rainfall station based on the density of rainfall stations;

[0010] Step 3: Construct flash flood disaster warning methods: Construct flash flood disaster warning methods, including single-station warning, surface rainfall warning and multi-station warning;

[0011] Step 4. Determine the warning method according to the type of rainfall station: Collect rainfall data from each rainfall station in the area where the protection object is located in real time. If the observed rainfall at a rainfall station exceeds the warning threshold, first determine the type of the rainfall station, and then select the corresponding warning method for warning.

[0012] Furthermore, the specific classification method of classifying all normal flood reporting rainfall stations in the area where the protection object is located according to their relative positions to the protection object in step 1 is:

[0013] All rainfall stations that normally report floods are divided into four categories according to their relative positions to the protection objects, namely Type 1 stations, Type 2 stations, Type 3 stations, and Type 4 stations;

[0014] Type 1 site: The rainfall site within a radius of x km with the protected object as the center is a Type 1 site; x is determined by the density of rainfall sites in the area, which is the area of ​​the area divided by the number of sites in the area;

[0015] Type 2 site: The upstream basin is extracted with the protected object as the basin outlet. The rainfall sites outside the x km radius of the protected object and within the upstream basin are Type 2 sites;

[0016] Type 3 site: The rainfall site in the x km buffer zone outside the upstream basin of the protected object is a Type 3 site;

[0017] Type 4 site: other sites except the first three types of sites.

[0018] Furthermore, the area where the protected object is located includes the upstream basin of the protected object and a 5km buffer zone; the value range of x is 3 to 5.

[0019] Furthermore, the manner of establishing the association between the protection object and the rainfall site according to the rainfall site density in step 2 is specifically as follows:

[0020] When the density of rainfall stations in the upstream basin of the protected object is less than or equal to the rainfall station density threshold y km 2 / station, that is, the distribution of rainfall stations is dense, then the protection object is associated with Type 1 stations and Type 2 stations; when the density of rainfall stations in the upstream basin of the protection object is greater than the threshold y km 2 / station, that is, the rainfall stations are sparsely distributed, and the protection object is associated with Type 1 stations, Type 2 stations, and Type 3 stations; Type 4 stations are not associated with villages.

[0021] Furthermore, the rainfall station density threshold y km 2 The value of the station is affected by the basin climate, rainfall characteristics, and the average station density of the province, which is 5-50km 2 / stand.

[0022] Furthermore, the single-station warning in step 3 is: among the multiple rainfall stations associated with the protection object, only a single station monitors rainfall exceeding the warning threshold, then the flash flood disaster warning system issues a warning for the protection object; the surface rainfall warning is: using the observed rainfall of multiple rainfall stations associated with the protection object to calculate the surface rainfall in the upstream basin, when the surface rainfall ≥ the warning threshold * α, the flash flood disaster warning system issues a warning for the protection object, where α is the reduction coefficient, α∈(0,1); the multi-station warning is: when the surface rainfall warning is not triggered, that is, the surface rainfall < the warning threshold * α, if the observed rainfall of more than half of the rainfall stations associated with the protection object is greater than or equal to the warning threshold, then the flash flood disaster warning system issues a warning for the protection object, otherwise, the flash flood disaster warning system does not issue a warning for the protection object.

[0023] Furthermore, the specific process of first determining the type of the rainfall station and then selecting the corresponding warning method for warning in step 4 is as follows: if the rainfall station is a Type 1 station of the protection object, a single-station warning method is used for warning; if the rainfall station is a Type 2 or Type 3 station of the protection object, the warning method is further determined according to the upstream basin area of ​​the protection object. If the basin area is less than the basin area threshold Akm 2 , then the single-station warning method is used directly for warning; if the basin area is large ≥ the basin area threshold Akm 2 , then calculate the basin surface rainfall, when the surface rainfall ≥ warning threshold * α, the flash flood disaster warning system will issue a warning for the protection object; conversely, when the surface rainfall < warning threshold * α, it is determined whether the rainfall at more than half of the stations is greater than the warning threshold. If so, the flash flood disaster warning system will issue a warning for the protection object, if not, the flash flood disaster warning system will not issue a warning for the protection object.

[0024] Furthermore, the watershed area threshold A ranges from 50 to 100.

[0025] The beneficial effects of the present invention are as follows: the method of the present invention solves the problem that the existing flash flood disaster warning methods are difficult to consider the uneven spatial distribution of disaster-causing rainstorms, and can take into account various situations such as the rainfall center in the upstream basin and the protection object, thereby reducing the false alarm rate and missed alarm rate of flash flood disaster warnings and improving the accuracy of flash flood disaster warnings.

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the process of the method of the present invention;

[0028] Figure 2 Schematic diagram of the rainfall station classification process. DETAILED DESCRIPTION

[0029] The present invention discloses a flash flood disaster early warning method based on the association between the protection object and the rainfall station, such as Figure 1 As shown, the method comprises the following steps:

[0030] Step 1: Classify rainfall stations: For protected objects (such as villages), all rainfall stations that normally report floods in the area where the protected object is located (including the upstream basin of the target protected object and the 5km buffer zone) are divided into four categories according to their relative positions to the protected object: Type 1 stations, Type 2 stations, Type 3 stations, and Type 4 stations. Figure 2 The specific classification is as follows:

[0031] Type 1 site: The rainfall site within the radius of x km with the protected object as the center is a Type 1 site. This type of site can warn of flash floods caused by local heavy rainfall at the protected object. Among them, x is determined according to the density of rainfall sites in the area (the density of rainfall sites is the area of ​​the area divided by the number of sites in the area), and is generally 3 to 5.

[0032] Type 2 site: The upstream basin is extracted with the protected object as the basin outlet. The rainfall site outside the x km radius of the protected object and within the upstream basin is a Type 2 site. This type of site can warn of flash flood disasters caused by heavy rainfall upstream, which may cause a surge in flow at the downstream protected object.

[0033] Type 3 stations: Rainfall stations in the x km buffer zone outside the upstream watershed of the protected object are Type 3 stations. This type of station can make up for the sparse rainfall stations in the area where the protected object is located.

[0034] Type 4 site: other sites except the first three types of sites.

[0035] Step 2: Establish the association between the protected object and the rainfall station: Calculate the density of rainfall stations in the upstream basin of the protected object, and establish the association between the protected object and the rainfall station based on the density of rainfall stations, as follows:

[0036] When the density of rainfall stations in the upstream basin of the protected object is less than or equal to the rainfall station density threshold y km 2 / station, that is, the distribution of rainfall stations is dense, then the protection object is associated with Type 1 stations and Type 2 stations; when the density of rainfall stations in the upstream basin of the protection object is greater than the rainfall station density threshold y km 2 / station, that is, the rainfall stations are sparsely distributed, and the protection objects are associated with Type 1 stations, Type 2 stations, and Type 3 stations; Type 4 stations are not associated with villages.

[0037] Among them, the rainfall station density threshold y km 2 The value of the station is affected by the basin climate, rainfall characteristics, average station density of the province and other factors, and is generally 5 to 50 km 2 / station; for areas with large differences in rainfall spatial distribution or relatively high average station density in the province, a smaller value can be taken; for areas with small differences in rainfall spatial distribution or relatively low average station density in the province, a larger value can be taken.

[0038] Step 3, construct flash flood disaster warning mode: construct flash flood disaster warning mode, including single-station warning, surface rainfall warning and multi-station warning. Among them, single-station warning means that among the multiple rainfall stations associated with the protection object, only a single station monitors rainfall exceeding the warning threshold, then the flash flood disaster warning system issues a warning for the protection object; surface rainfall warning means that the observed rainfall of multiple rainfall stations associated with the protection object is used to calculate the surface rainfall in the upstream basin. When the surface rainfall ≥ the warning threshold * α, the flash flood disaster warning system issues a warning for the protection object, where α is the reduction coefficient, α∈(0,1), and the area with large differences in rainfall spatial distribution can take a smaller value, and the area with small differences in rainfall spatial distribution can take a larger value; multi-station warning means that when the surface rainfall warning is not triggered, that is, the surface rainfall < the warning threshold * α, if the observed rainfall of more than half of the rainfall stations associated with the protection object is greater than or equal to the warning threshold, the flash flood disaster warning system issues a warning for the protection object and notifies the relevant protection objects to take preventive measures in time. Otherwise, the flash flood disaster warning system does not issue a warning for the protection object.

[0039] Step 4. Determine the warning method based on the type of rainfall station: Collect rainfall data from each rainfall station in the area where the protected object is located in real time. If the observed rainfall at a rainfall station exceeds the warning threshold, first determine the type of the station. If the rainfall station is a Type 1 station of the protected object, use the single-station warning method for warning. If the rainfall station is a Type 2 or Type 3 station of the protected object, then further determine the warning method based on the upstream basin area of ​​the protected object. If the basin area is small ( 2 ), the single station warning method is directly used for early warning; if the basin area is large (≥Akm 2 ), then calculate the basin area rainfall. When the area rainfall ≥ warning threshold * α, the flash flood disaster warning system will issue a warning for the protection object; conversely, when the area rainfall < warning threshold * α, determine whether the rainfall at more than half of the stations is greater than the warning threshold. If so, the flash flood disaster warning system will issue a warning for the protection object. If not, the flash flood disaster warning system will not issue a warning for the protection object. Where A is the basin area threshold, ranging from 50 to 100. A larger value can be used in areas with a large basin slope, and a smaller value can be used in areas with a small basin slope.

[0040] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred arrangement scheme, a person skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.​

Claims

1. A flash flood disaster early warning method based on the association between protection objects and rainfall stations, characterized in that: The method comprises the following steps: Step 1: Classify the rainfall stations: classify all rainfall stations that normally report floods in the area where the protected object is located according to their relative positions to the protected object; The specific classification is: All rainfall stations that normally report floods are divided into four categories according to their relative positions to the protection objects, namely Type 1 stations, Type 2 stations, Type 3 stations, and Type 4 stations; Type 1 site: The rainfall site within a radius of x km with the protected object as the center is a Type 1 site; x is determined by the density of rainfall sites in the area, which is the area of ​​the area divided by the number of sites in the area; Type 2 site: The upstream basin is extracted with the protected object as the basin outlet. The rainfall sites outside the x km radius of the protected object and within the upstream basin are Type 2 sites; Type 3 site: The rainfall site in the x km buffer zone outside the upstream basin of the protected object is a Type 3 site; Type 4 site: other sites except the first three types of sites; Step 2: Establish the association method between the protected object and the rainfall station: calculate the density of rainfall stations in the upstream basin of the protected object, and establish the association method between the protected object and the rainfall station based on the density of rainfall stations; The specific method of establishing the association between the protection object and the rainfall site according to the rainfall site density is: When the density of rainfall stations in the upstream basin of the protected object is less than or equal to the rainfall station density threshold y km 2 / station, that is, the distribution of rainfall stations is dense, then the protection object is associated with Type 1 stations and Type 2 stations; when the density of rainfall stations in the upstream basin of the protection object is greater than the threshold y km 2 / station, that is, the rainfall stations are sparsely distributed, and the protection objects are associated with Type 1 stations, Type 2 stations, and Type 3 stations; Type 4 stations are not associated with villages; Step 3: Construct flash flood disaster warning methods: Construct flash flood disaster warning methods, including single-station warning, surface rainfall warning and multi-station warning; The single-station warning is: among the multiple rainfall stations associated with the protection object, only a single station monitors rainfall exceeding the warning threshold, then the flash flood disaster warning system issues a warning for the protection object; the surface rainfall warning is: using the observed rainfall of multiple rainfall stations associated with the protection object to calculate the surface rainfall in the upstream basin, when the surface rainfall ≥ the warning threshold * α, the flash flood disaster warning system issues a warning for the protection object, where α is the reduction coefficient, α∈(0,1); the multi-station warning is: when the surface rainfall warning is not triggered, that is, when the surface rainfall < the warning threshold * α, if the observed rainfall of more than half of the rainfall stations associated with the protection object is greater than or equal to the warning threshold, then the flash flood disaster warning system issues a warning for the protection object, otherwise, the flash flood disaster warning system does not issue a warning for the protection object; Step 4: Determine the warning method according to the type of rainfall station: collect rainfall data of each rainfall station in the area where the protection object is located in real time. If the observed rainfall at a rainfall station exceeds the warning threshold, first determine the type of the rainfall station, and then select the corresponding warning method for warning; The specific process of first determining the type of the rainfall station and then selecting the corresponding warning method for warning is as follows: if the rainfall station is a Type 1 station of the protection object, a single station warning method is used for warning; if the rainfall station is a Type 2 or Type 3 station of the protection object, the warning method is further determined according to the upstream basin area of ​​the protection object. If the basin area is less than the basin area threshold A km 2 , then the single station warning method is used directly for warning; if the basin area ≥ the basin area threshold A km 2 , then calculate the basin surface rainfall, when the surface rainfall ≥ warning threshold * α, the flash flood disaster warning system will issue a warning for the protection object; conversely, when the surface rainfall < warning threshold * α, it is determined whether the rainfall at more than half of the stations is greater than the warning threshold. If so, the flash flood disaster warning system will issue a warning for the protection object, if not, the flash flood disaster warning system will not issue a warning for the protection object.

2. A flash flood disaster early warning method based on the association between protection objects and rainfall stations according to claim 1, characterized in that: The area where the protected object is located includes the upstream basin of the protected object and the 5km buffer zone; the value range of x is 3 to 5.

3. A flash flood disaster early warning method based on the association between protection objects and rainfall stations according to claim 1, characterized in that: The rainfall station density threshold y km 2 The value of the station is affected by the basin climate, rainfall characteristics, and the average station density of the province, which is 5-50km 2 / stand.

4. A flash flood disaster early warning method based on the association between protection objects and rainfall stations according to claim 1, characterized in that: The watershed area threshold A ranges from 50 to 100.

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