JP5119367B2 - Disaster danger area prediction device - Google Patents

Description

The present invention relates to disaster risk area prediction device to predict the danger zone of disaster due to rainfall in the target area.

  In recent years, changes in weather, such as intense heat and heavy snow, tend to be severe, and “guerrilla heavy rain” (local heavy rain), which can cause heavy rain locally, is one of them. In the case of this guerrilla heavy rain, the rain that has fallen flows downstream along the surface of the ground before it penetrates underground. Has been found to be a danger zone.

  However, in the conventional disaster risk prediction method, the prediction of the danger zone caused by the local heavy rain exceeding the assumed amount is not sufficient, and the prediction itself is difficult (for example, the following patents) Reference 1). For this reason, the present situation is that the local government cannot properly guide emergency evacuation sites.

JP 2006-127156 A

The present invention has been proposed in view of the above, accurately predict the risk zone generated by local heavy rain, accidents dangerous area prediction apparatus can appropriately perform guidance such as emergency shelters based on the prediction The purpose is to provide.

To achieve the above object, a first aspect of the present invention, a disaster Critical prediction device for predicting the risk zone of disaster at local heavy rain in the target area, the ground surface of the target area When it is divided into 10m x 10m mesh, altitude data is given to each mesh, and the surface water of each mesh flows out to the mesh with the steepest downward slope with the mesh among the surrounding meshes It is assumed that the FA value calculating means for calculating the FA value, which is a value obtained by accumulating how many meshes in the target area the water flows into the mesh, and the regular use of the FA value obtained by the FA value calculating means. the FA logarithm is logarithmic, and FA values logarithmic conversion means for obtaining for each mesh, divided into five groups according to their size the FA logarithm, FA value is not more 100 to 1000, FA The area where the third group's identification information is assigned from the smaller numerical value is usually not flowing or is flowing like a stream even if it is flowing, but the potential for turbidity in localized heavy rain It is determined that the area is a river area, and the area where the FA value is 0 or more and 10 or less and the identification information of the first group from the smaller FA logarithm is assigned is a temporary evacuation site in case of heavy local rain It is characterized by comprising display means for discriminating that it is a settable area and displaying the screen by giving identification information set for each group to a mesh.
The invention according to claim 2 is the invention according to claim 1, wherein the altitude data of the mesh is compared with the altitude data of the mesh around the mesh, and the most downward slope with respect to the mesh A slope angle calculating means for calculating a slope angle between the mesh and the maximum slope angle of the mesh, and among the meshes determined as the potential river, the mesh having the maximum slope angle equal to or greater than a predetermined angle It is determined that a region having a can be a debris flow starting point at the time of local heavy rain.
The invention described in claim 3 is the invention described in claim 2, wherein the predetermined angle is set to 5 degrees .
The invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the identification information is color information .

  In disasters caused by local heavy rains in recent years, the rain that has fallen flows downstream along the surface of the ground before penetrating underground, and it suddenly flows as turbidity in an area that has not been envisaged, It quickly became clear that the area would become a danger zone. On the other hand, the FA value representing the accumulated water amount has conventionally been utilized mainly in an intermediate process when specifying the range of a basin (water collection area). The present inventor considered that the FA value and the danger zone generated during the heavy local rain have a direct relationship. Then, we examined whether or not the danger zone that occurs during the local heavy rain could be clearly displayed on the map. Therefore, for example, when the FA value is 100000 at the maximum, 0 to 100,000 is divided into five, 0 to 20000 is displayed in green, 20000 to 40,000 is displayed in five colors, and displayed on the map. The area becomes green, and the area other than green is displayed only in a streak shape, and the area in a large river is also displayed in a thin streak shape.

  Therefore, the present inventor has focused on the common logarithm value of the FA value (FA logarithm value), found that the above-mentioned problem that cannot be analyzed can be solved by using the FA logarithm value, and extracted the danger area from the target area And I succeeded in superbly displaying it on the map.

  By extracting dangerous areas on this map, it has become possible to accurately predict dangerous areas during local heavy rains that were previously unpredictable. In addition, emergency evacuation sites and evacuation routes can be appropriately set based on this prediction. In addition, based on the prediction, by calling on the residents for disaster prevention, awareness of disaster prevention can be raised on a daily basis. As described above, the present invention provides accurate information such as designation of a dangerous area, setting of an evacuation place and an evacuation route, etc., for a local heavy rain that has been difficult to predict and increases damage. It can contribute epoch-makingly to the disaster prevention of the local heavy rain which tends to occur frequently in recent years.

That is, in the present invention, the common logarithm of the FA value for each mesh is obtained and divided into five groups according to the magnitude of the FA logarithm, and the FA value is 100 to 1000 and the FA logarithm is small. The area where the identification information of the third group from the side is given is the area of a potential river that usually does not flow or is about a stream even if it is flowing, but becomes turbid in local heavy rain The area where the FA value is 0 or more and 10 or less and the identification information of the first group from the smaller FA logarithm value is assigned is an area where temporary evacuation site can be set in the case of local heavy rain Since the identification information set for each group is added to the mesh and displayed on the screen, the screen (map) to which the identification information is assigned is used to identify the danger area during localized heavy rain. To accurately predict It is now possible to properly guide emergency evacuation sites based on the prediction.

In addition, in the present invention, it has become possible to predict accurately the area where a potential river was a traditional unpredictable.
In addition, “potential river” is a stream that is about the size of a creek even if water is not flowing or flowing normally, but when it is hit by heavy rain, rainwater concentrates from the surroundings and becomes muddy flow at once. An area that ends up.

  In addition, based on the prediction, by calling on the residents for disaster prevention, awareness of disaster prevention can be raised on a daily basis.

  In the present invention, when divided into five groups according to the size of the FA logarithm, the area to which the identification information of the first group from the smaller FA logarithm or the mesh is 10 meters × 10 In the case of meters, an area having an FA value in the range of 0 to 10 is a safe area where rainwater does not concentrate even in the case of localized heavy rain, and thus corresponds to an area where temporary evacuation sites can be set. As a result, the evacuation site can be determined more accurately, and the evacuation route that leads to the evacuation site while avoiding the potential river can be set appropriately. It was.

  In conventional evacuation routes, there are cases where people evacuate to an evacuation site such as an elementary school across the area of a potential river. There was a problem in setting the evacuation route. In the present invention, since a potential river can be extracted and an evacuation place can be set, an evacuation route can be appropriately set from the residential area to the evacuation place so as not to cross the potential river.

Further, in the present invention, an area having a mesh that is a potential river area and has a maximum slope angle of a predetermined angle (for example, 5 °) or more can be a debris flow starting point at the time of local heavy rain. did. Here, the debris flow starting point is a point where the debris flow starts as a debris flow starting point due to a landslide on a slope.
Conventionally, it has been known that debris flow during local heavy rains is likely to be caused by a place where the slope is steep, but a method for rationally identifying the place has not been developed. As a result of analyzing many cases, the present inventor found that a place where the debris flow starting point can be a potential river region and a region having a mesh whose maximum slope angle is equal to or greater than a predetermined angle. I found out. In other words, in the present invention, a place that can be a debris flow starting point that could only be specified by experience can be specified from the FA value and maximum slope angle of the mesh. By informing the residents in advance of information on the location that can be the debris flow starting point, it is possible to raise awareness of disaster prevention, and it is also possible to accurately perform evacuation and other actions when local heavy rain occurs.

It is a block diagram which shows the structure of the disaster risk area prediction apparatus of this invention. It is explanatory drawing of the calculation procedure which FA value calculation means performs, (a) shows the case where altitude data is given to each mesh, (b) shows the case where the direction of the water which flows out from each mesh is digitized, (C) shows the FA value (cumulative water amount) of each mesh, and (d) shows the numerical value given to the direction of the flowing water. It is a partial enlarged view of the map when the mesh of the target area I is divided into five groups and displayed in the disaster risk degree prediction diagram. FIG. 5 is a partial enlarged view of a map displaying places that can become debris flow starting points from a target area I in a disaster risk prediction map. FIG. 5 is a partial enlarged view of a map obtained by extracting and displaying an area having an FA value of 100 to 1000 from a mesh of a target area II in a disaster risk degree prediction diagram. It is a partial enlarged view of the map which extracted and displayed the area | region where FA value is 0-10 from the mesh of the target area II with a disaster risk level prediction figure.

FIG. 1 is a block diagram showing the configuration of the disaster risk area prediction apparatus of the present invention. In FIG. 1, a disaster risk area prediction apparatus 1 according to the present invention is an apparatus for predicting a disaster risk area due to rainfall in a target area, and includes an FA value calculation means 2, an FA value logarithmic conversion means 3, and a display means 4. And.

  The FA value calculation means 2 divides the ground surface of the target area into meshes, and assigns altitude data to each mesh, so that the surface water of each mesh descends most among the surrounding meshes with the mesh. Assuming that it flows out to a mesh with a steep slope, an FA value that is a value obtained by accumulating how many meshes in the target area water flows into the mesh is calculated.

  The FA value logarithmic conversion means 3 obtains an FA logarithmic value which is a common logarithm of the FA value for each mesh obtained by the FA value calculating means 2.

  The display means 4 divides the FA logarithmic value into a plurality of groups according to the size, and gives the identification information set for each group to the mesh and displays it on the screen.

  The disaster risk predicting apparatus 1 is mainly configured by a microcomputer including a CPU, a ROM, and a RAM. Each of the means 2, 3, and 4 includes software functions executed by the CPU according to a ROM program, It is configured.

Next, the calculation performed by the FA value calculation means 2 will be described with reference to FIG.
FIG. 2 is an explanatory diagram of the calculation procedure performed by the FA value calculation means. (A) shows a case where the target area is divided into meshes and altitude data is given to each mesh, and (b) flows out from each mesh. The case where the direction of water is digitized is shown, (c) shows the FA value (cumulative water amount) of each mesh, and (d) shows the numerical value given to the direction of flowing water.

  When performing water flow analysis in a target area when a local heavy rain falls, in the present invention, as shown in FIG. 2A, first, the ground surface of the target area is divided into meshes, and elevation data is assigned to each mesh. Is granted. For this mesh and elevation data, for example, a “base map information numerical elevation model” published by the Geospatial Information Authority of Japan is used. Various lengths such as 10 meters (m) and 5 m are employed for one side of the mesh.

  Then, it is assumed that the surface water of each mesh flows out to the mesh having the steepest downward slope with respect to the mesh among the surrounding meshes. For example, in FIG. 2A, in the case of the mesh p (elevation “7”) located in the center, water flows out toward the mesh q (elevation “1”) located in the upper left among the eight surrounding meshes. Will do. The mesh q not only flows from the mesh p but also flows from the mesh r below, and further flows from the mesh s below the mesh r.

  The FA value is a value obtained by accumulating how many meshes in the target area water flows into the mesh.

  The FA value calculation means 2 digitizes the direction of water flowing out from each mesh using numbers assigned to each of the eight directions as shown in FIG. For example, since the center mesh p flows out in the upper left direction, “8” is given in FIG. 2B, and the mesh r flows out in the upper direction, so “1” is given in FIG. 2B. Has been. Since the outflow of water from the mesh located on the outermost side is excluded from the calculation, the numerical value given to the mesh located on the outermost side in FIG. 2B is “0”.

  The FA value calculation means 2 finally obtains the FA value by a predetermined calculation process using the numerical values shown in FIG. For example, paying attention to the mesh t, water flows into the mesh t from the meshes q, u, and v, flows into the mesh q from the meshes p and r, and flows into the mesh r from the mesh s. When accumulated in mesh t, it flows from six meshes p, q, r, s, u, and v. Therefore, as shown in FIG. 2C, the FA value (cumulative water amount) of mesh t is “6”. Become.

  In this way, the FA value calculation means 2 divides the ground surface of the target area into meshes and gives elevation data to each mesh so that the surface water of each mesh is between the meshes of the surrounding meshes. Assuming that it flows out to the mesh with the steepest downward slope, the FA value which is a value obtained by accumulating how many meshes in the target area the water flows into is calculated.

Next, Table 1 shows the calculation results when the present invention is applied to an actual target area.

  The target area I (analysis range) of this application example is a substantially square area of about 24.5 km × about 24.5 km on the map, and the “base map information numerical elevation model” used in this application example is The target area I is created by dividing the target area I into 10 m × 10 m meshes and assigning altitude data to each mesh. The total number of meshes in this analysis range was 6,163,963.

  In Table 1, items are “FA value”, “FA logarithm value”, “number of meshes (number of the same FA value)”, and “ratio to the total number of meshes (FA value ratio) (%)” in order from the leftmost column. . As shown in Table 1, the FA value has a minimum value of “0” and a maximum value of “99993”. The FA value “0” is a mesh in which water does not flow in from other meshes, and exists mainly at a high altitude. The FA value “99993” is a mesh into which water flows in from a cumulative number of 99993 meshes, and exists mainly in rivers flowing through lowlands.

  When this FA value is divided into 5 as it is in order to extract a dangerous area during local heavy rain, as can be seen from Table 1, the divided region of the group with a small FA value has a FA value in the range of 0 to 19999. When this divided area is displayed in green, 99.99% on the map becomes green, and it is impossible to extract a dangerous area from the map.

  Therefore, in the present invention, as shown in Table 1, for each FA value from “0” to “99993”, an FA logarithm value that is a common logarithm was obtained.

  The FA logarithmic value exists for each FA value from 1 to 99993, but when the FA value is “0”, the common logarithm cannot be calculated. ”Is added to“ 1 ”, and the FA logarithmic value is set to“ 0 ”. Alternatively, the FA logarithmic value may be obtained by adding “1” to all FA values. For example, when 1 is added to the FA value 100 to be 101, the FA logarithmic value increases from 2 to 2.0043. This difference can be said to be an error that can be ignored in setting the region.

  Thus, in the present invention, the FA value (0 to 99993) is logarithmically converted to obtain the FA log value (0 to 4.9999970), and the FA log value is divided into a plurality of groups. When the number of groups is 2, dangerous areas cannot be extracted and should be 3 or more. In the following example, a case where there are five groups will be described.

  FIG. 3 is a disaster risk prediction diagram and is a diagram showing a partial enlargement of the map when the mesh of the target area I is divided into five groups and displayed. The grouping was performed by equally dividing it into five according to the magnitude of the FA logarithmic value, and A, B, C, D, E were set in order from the smallest value group. In FIG. 3, group A is white, group B is 25% gray, group C is 50% gray, group D is 80% gray, and group E is black.

  In this example, white, gray, and black are identified, but in actuality, the color may be displayed in green, yellow, red, or various hatchings. In addition, it is possible to accurately identify which point on the actual topography each group has by superimposing FIG. 3 on the topographic map of this region and from the longitude and latitude information of FIG.

  In FIG. 3, group A is a group in which the FA logarithm value is 0 to 0.954243 and the FA value is in the range of 0 to 9, and the meshes existing in this range are relative to the entire target area I (total number of meshes). Accounting for 82.4%.

  Group B is a group in which the FA logarithm value is 1.000 to 1.9963535 and the FA value is in the range of 10 to 99, and the meshes existing in this range are 12 for the entire target area I (total number of meshes). It accounts for 1%.

  Group C is a group in which the FA logarithm value is 2.000000 to 2.999565 and the FA value is in the range of 100 to 999, and the meshes existing in this range are 4 for the entire target area I (total number of meshes). It accounts for 0.0%.

  Group D is a group in which the FA logarithm value is 3.0000 to 3.9999957 and the FA value is in the range of 1000 to 9999, and the mesh existing in this range is 1 for the entire target area I (total number of meshes). It accounts for 1%.

  The group E is a group in which the FA logarithm value is 4.000 to 4.9999970 and the FA value is in the range of 10,000 to 99993, and the mesh existing in this range is 0 with respect to the entire target area I (total number of meshes). It accounts for 4%.

  Consider groups A, B, C, D, and E. Group A accounts for 82.4% of the total target area I, and even if local heavy rain occurs, for example, rain of 70 mm or more per hour, the FA value, which is the cumulative water volume, is 10 or less. In the present invention, when this region, that is, the target area is divided into five groups according to the size of the FA logarithm, It is determined that this is an area where temporary evacuation sites can be set during local heavy rain. This area A is an area where the accumulated water amount is small and debris flow does not occur reliably. When determining an evacuation place when a local heavy rain occurs, if an evacuation place is selected from the group A area, the evacuation place can be determined accurately.

  Group B is a relatively safe area, although it is not as much as Group A, but the accumulated amount of water is small, and even in the case of localized heavy rain, rainwater does not concentrate and become turbid.

  In Group C, the amount of normal accumulated water is not so much as rivers, and usually there is little flow or no flow in the first place. When heavy rain such as local heavy rain falls, it suddenly happens. It is in good agreement with the area considered to be a river, that is, a potential river during heavy rain.

  In this potential river region C, debris flow is not predicted to occur, and in recent heavy local rains, distress occurs more frequently in such regions than large rivers. Potential rivers such as roads next to private houses, where no turbulent flow is expected to flow there, are possible. In the present invention, an area that closely matches such a potential river can be extracted as a group and specified as a dangerous area.

  Groups D and E have a large FA value, which is the cumulative amount of water, so they are almost the same as rivers, and even when there is no rain, water is always flowing, and people do not approach this place even during normal times. Because of the increased water volume when it rains, it is a place where people cannot get closer.

  In this way, in the present invention, the common logarithm of the FA value for each mesh is obtained, divided into a plurality of groups according to the magnitude of the FA logarithmic value, and identification information set for each group is given to the mesh. Because the screen is displayed, the screen (map) with the identification information can be used to accurately predict the danger zone during local heavy rains, and guide emergency evacuation sites based on the prediction. Now it can be done properly.

  That is, in the present invention, when the group is divided into five groups according to the size of the FA logarithmic value, the region C to which the identification information of the third group from the smallest FA logarithmic value is assigned is the region of the potential river. As a result, it was made possible to accurately predict areas that would become potential rivers that were previously unpredictable. In addition, based on the prediction, by calling on the residents for disaster prevention, awareness of disaster prevention can be raised on a daily basis.

  Further, in the present invention, when divided into five groups according to the magnitude of the FA logarithm, the area A to which the identification information of the first group from the smaller FA logarithm is given a local heavy rain. Since it is difficult to collect water on the ground surface even when it is broken, it is determined that it is a safe area and therefore corresponds to a temporary evacuation area setting area, so that the evacuation area can be determined more accurately. In addition, it has become possible to appropriately set an evacuation route that leads to the evacuation site while avoiding a potential river.

  In the conventional evacuation route, there is a case where the evacuation area crosses the area C of the potential river and evacuates to an evacuation site such as an elementary school over there. There were cases of distress where nine people were killed by being caught in the muddy stream generated by heavy rain, and there was a problem in the setting of evacuation routes. In the present invention, since a potential river can be extracted and an evacuation place can be set, an evacuation route can be appropriately set from the residential area to the evacuation place so as not to cross the potential river.

Next, setting of a place that can be a debris flow starting point in the target area I will be described.
FIG. 4 is a partial enlarged view of a map that displays places that can be debris flow starting points from the target area I in the disaster risk degree prediction diagram. This FIG. 4 is the same area as FIG. 3 above. In the figure, the region C shown in 50% gray is the group 3 (potential river), and the region X shown in 25% gray is the maximum slope angle. Is a region where the maximum slope angle is 5 ° or less. A place that can be a debris flow starting point is a place where region C and region X overlap.

In the present invention, a place that can be a debris flow starting point in a local heavy rain is set by the following procedure. First, the altitude data of the mesh in the target area I is compared with the altitude data of the mesh around the mesh, and the slope angle between the mesh that is the most inclined downward with respect to the mesh is determined as the maximum slope of the mesh. Calculate as an angle. Specifically, when the altitude data of the mesh is h1, the altitude data of the mesh having the largest altitude difference with the mesh among the surrounding eight meshes is h2, and the center-to-center distance between the meshes is ΔL. The maximum slope angle α is obtained by α = tan ⁻¹ (h2−h1) / ΔL.

  Next, among the meshes determined as potential rivers (mesh constituting group C), an area having a mesh whose maximum slope angle α is equal to or larger than a predetermined angle is determined as a debris flow starting point at the time of local heavy rain. It is determined that the place can be. Here, the predetermined angle is preferably 5 °. If the maximum slope angle is 5 ° or less, even if the potential river becomes muddy current, the slope is gentle, so it can not be the start point of landslide flow, but if it exceeds 5 °, the slope gradually becomes steep, so landslide This is because there is a greater possibility of becoming a starting point.

  As described above, in the present invention, the region X that is a potential river region C and has a mesh having a maximum slope angle equal to or larger than a predetermined angle can be a debris flow starting point in a local heavy rain (C and X). Conventionally, it has been known that debris flows during local heavy rains are likely to occur in places with steep slopes, but no method for rationally identifying such places has been developed. This is because 50m and 90m mesh digital elevation models were common in Japan before the base map information digital elevation model was released, and it was difficult to obtain a high-density digital elevation model such as 10m mesh. . As a result of analyzing many cases, the present inventor found that a place where the debris flow starting point can be a potential river region and a region having a mesh whose maximum slope angle is equal to or greater than a predetermined angle. I found out. In other words, in the present invention, a place that can be a debris flow starting point that could only be specified by experience can be specified from the FA value and maximum slope angle of the mesh. By informing the residents in advance of information on the location that can be the debris flow starting point, it is possible to raise awareness of disaster prevention, and it is also possible to accurately perform evacuation and other actions when local heavy rain occurs.

  In the above description, the temporary evacuation site setting possible area is the area A of the first group from the smaller FA logarithm, but it can also be determined as follows. That is, by using the “number of meshes (number of the same FA value)” and “ratio to the total number of meshes (FA value ratio) (%)” of Table 1 corresponding to the target area I described above, temporary local rain during heavy rain Decide where the evacuation site can be set. Here, the same FA value number is a value obtained by counting the number of meshes having the same FA value, and the FA value ratio is the number of meshes having the same FA value (the same FA value number). Is the ratio of the total number of meshes in the target area.

  Using this Table 1, the FA value ratio is sequentially added from the time when the FA value is 0, and the FA value is obtained when the sum total is 80% or more, and the FA value is 0 to 80% or more. A region having a mesh up to the FA value at that time is determined to be a region where a temporary evacuation place can be set during a local heavy rain.

  The FA value ratio is sequentially added from the time when the FA value is 0, and the area having the mesh up to the FA value when the sum is 80% or more does not concentrate rainwater even in the case of local heavy rain. Therefore, it is a safe area and is therefore suitable as a temporary evacuation area setting area. This area substantially corresponds to Group A when the target area is divided into five.

  In the above description, the area of the potential river is the third group area from the one with the smaller FA logarithm out of the five groupings, but can be determined as follows. In other words, the target area is divided by a mesh of 10 meters × 10 meters, the FA value of each mesh is obtained, a group consisting of meshes whose FA value is 100 or more and 1000 or less is formed, and the group is an area of a potential river It is determined that

  FIG. 5 is a partial enlarged view of a map obtained by extracting and displaying an area having an FA value of 100 to 1000 from the mesh of the target area II in the disaster risk degree prediction diagram. The target area II applied here is an approximately square area of about 21.0 km × about 21.0 km on the map, and the “base map information numerical elevation model” used in this application example is the target area II. It is created by dividing into 10 m × 10 m meshes and assigning altitude data to each mesh.

  In FIG. 5, an area M is obtained by extracting an area having an FA value of 100 to 1000 from all the meshes of the target area II. In this area M, the accumulated water amount (FA value) is smaller than the accumulated water amount of the river. It is a place where turbidity is not expected to flow there, like a road right next to a private house, but it is an area where debris can flow and become turbidity in localized heavy rain. This area substantially corresponds to group C when the target area is divided into five.

  Further, in the above description, the temporary evacuation site setting possible area is the area A of the first group from the smaller FA logarithm value, or the FA value ratio is sequentially added from the time when the FA value is 0 and the addition is performed. Although the region having the mesh up to the FA value when the total is 80% or more (CandX in FIG. 3) is used, it can be determined as follows. In other words, the target area is divided by a mesh of 10 meters × 10 meters, the FA value of each mesh is obtained, and a group consisting of meshes whose FA values are 0 or more and 10 or less is formed. Since it is difficult to gather and is relatively safe, it is determined that the group is a temporary evacuation site setting area.

  FIG. 6 is a disaster risk prediction diagram, and is a partially enlarged view of a map in which an area having an FA value of 0 to 10 is extracted from the mesh of the target area II and displayed. In FIG. 6, an area N is an area where FA values of 0 to 10 are extracted from all meshes in the target area II. This area N is safe because rainwater does not concentrate even in the case of localized heavy rain. Therefore, it is suitable as a temporary evacuation area setting area. This area substantially corresponds to Group A when the target area is divided into five.

  3 to 6 described above, the present invention has been applied to the target areas I and II. However, the present invention was applied to 15 areas where disasters occurred due to recent local heavy rain. These target areas were substantially square areas with sides of 10 to 30 km. As a result of the application of the present invention, all of the target areas that were suddenly turbid and suffered disasters were present in the area of potential rivers defined by the present invention. In addition, 90% of the location that is the debris flow starting point exists in an area that can be the debris flow starting point defined by the present invention, and the effectiveness of the present invention can be said to be extremely high.

  As described above, in the present invention, by using the FA logarithm value, the danger area is extracted from the target area and displayed on the map. Can be accurately predicted. In addition, emergency evacuation sites and evacuation routes can be appropriately set based on this prediction. In addition, based on the prediction, by calling on the residents for disaster prevention, awareness of disaster prevention can be raised on a daily basis. As described above, the present invention can contribute epoch-makingly to disaster prevention of localized heavy rain that tends to occur frequently in recent years.

DESCRIPTION OF SYMBOLS 1 Disaster danger area prediction apparatus 2 FA value calculation means 3 FA value logarithmic conversion means 4 Display means A, B, C, D, E, M, N, X, Y Group, area

Claims (4)

A disaster risk area prediction device to predict the danger area of the disaster at the time of localized heavy rain in the target area,
The ground surface of the target area is divided into 10 m × 10 m meshes, and altitude data is given to each mesh, and the surface layer water of each mesh has the most downward slope with the mesh among the surrounding meshes. An FA value calculation means for calculating an FA value that is a value obtained by accumulating the number of meshes in the target area from which water flows into the mesh, assuming that it flows out to a sudden mesh;
FA value logarithmic conversion means for obtaining, for each mesh, an FA logarithm value that is a common logarithm of the FA value obtained by the FA value calculation means;
The FA logarithmic value is divided into five groups according to the size, and the area where the FA value is 100 or more and 1000 or less and the identification information of the third group from the smallest FA logarithm value is given, Usually, water is not flowing, or even if it is flowing, it is about a stream, but it is determined that it is a region of a potential river that becomes turbid in local heavy rain, and the FA value is 0 to 10 The area to which the identification information of the first group from the smaller FA logarithm is assigned is determined to be a temporary evacuation site setting area in the case of heavy rain, and the identification information set for each group is determined. Display means for giving a mesh and displaying the screen;
A disaster danger area prediction device characterized by comprising: The slope angle that compares the altitude data of the mesh with the altitude data of the mesh surrounding the mesh, calculates the slope angle between the mesh that is the most downward slope relative to the mesh, and sets the maximum slope angle of the mesh Computation means,
Of the meshes identified as potential river areas, the areas having meshes with the maximum slope angle greater than or equal to a predetermined angle are determined to be locations where debris flow can be started during localized heavy rain. The disaster risk prediction apparatus according to claim 1. The disaster risk prediction apparatus according to claim 2, wherein the predetermined angle is 5 degrees. The disaster risk area prediction device according to any one of claims 1 to 3, wherein the identification information is color information.