Stormwater runoff environment evaluation method and stormwater runoff environment evaluation device

Abstract

To provide a rainwater outflow environment evaluation apparatus capable of appropriately evaluating a rainwater outflow curbing effect using a green space.SOLUTION: A rainwater outflow environment evaluation apparatus 1 evaluates an outflow environment of rainwater in an evaluation target area including a paved surface and a green space surface as a ground surface. The rainwater outflow environment evaluation apparatus 1 includes: a catchment analysis section 111 that analyzes a catchment route where rainwater surface-flows on the paved surface and is caught based on geographical data that record a three-dimensional shape of the evaluation target area and land dividers of the ground surface and calculates a catchment route penetration amount of the rainwater that penetrates through the paved surface when the rainwater surface-flows along the catchment route; a green space analysis section 112 that, based on the geographical data, calculates a green space penetration amount of the rainwater that penetrates through the green space and calculates a green space storage amount of the rainwater that is caught via the catchment route, flows into the green space, and is stored; and an outflow environment evaluation section 113 that, based on the catchment route penetration amount, the green space penetration amount, and the green space storage amount, calculates a rainwater outflow curbed amount by which the outflow of the rainwater from the evaluation target area to outside thereof is curbed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stormwater runoff environment evaluation method and a stormwater runoff environment evaluation device. [Background technology]

[0002] In recent years, the risk of inland flooding due to sudden heavy rains has increased in urban areas where most of the ground surface is covered with pavement. Furthermore, there are concerns that combined sewer systems may discharge overflow water containing untreated sewage during rainfall, leading to water pollution in rivers and oceans and the deterioration of ecosystems. Both of these serious problems arise when rainwater exceeds the treatment capacity of the stormwater drainage system and flows into it.

[0003] Therefore, as a device for analyzing the situations in which these problems occur, Patent Document 1 discloses a rainwater runoff volume estimation device that estimates the amount of rainwater that flows into main waterways such as sewers and rivers depending on the amount of rainfall in the target area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-106477 Summary of the Invention [Problem to be solved by the invention]

[0005] The stormwater runoff volume estimation device disclosed in Patent Document 1 estimates the volume of stormwater runoff from a target area, as described above. Meanwhile, in recent years, measures to prevent stormwater from flowing out of the target area, including the stormwater drainage system, have become increasingly important from an environmental perspective. Under these circumstances, decentralized stormwater runoff prevention measures utilizing green spaces have received particular attention. However, in order to develop a green space layout plan that effectively implements these stormwater runoff prevention measures, a method for quantitatively evaluating the effectiveness of stormwater runoff prevention is desired. However, the stormwater runoff volume estimation device disclosed in Patent Document 1 does not take into account phenomena such as infiltration and temporary storage of rainwater as it flows over paved surfaces and into green spaces, and therefore was unable to properly evaluate the effectiveness of utilizing green spaces in preventing stormwater runoff.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a rainwater runoff environment evaluation method and a rainwater runoff environment evaluation device that enable appropriate evaluation of the effect of utilizing green spaces in suppressing rainwater runoff. [Means for solving the problem]

[0007] The present invention solves the above-mentioned problems, and a stormwater runoff environment evaluation method according to one embodiment of the present invention includes: A rainwater runoff environment evaluation method for evaluating the rainwater runoff environment in an evaluation target area having a paved surface and a green area as ground surfaces, a water collection analysis process for analyzing the water collection path when the rainwater flows over the pavement surface and is collected based on geographic data that records the three-dimensional shape of the area to be evaluated and the land classification of the ground surface, and calculating the water collection path infiltration amount, which indicates the amount of the rainwater that flows over the surface along the water collection path and infiltrates into the pavement surface; a green space analysis step of calculating a green space infiltration amount indicating the amount of rainwater that infiltrates into the green space based on the geographical data, and calculating a green space storage amount indicating the amount of rainwater that flows into and is stored in the green space after being collected through the water collection route; The method also includes a runoff environment evaluation process for calculating a rainwater runoff suppression amount, which indicates the amount of rainwater that has been suppressed from running off from the evaluation target area to outside the area, based on the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount. [Effects of the Invention]

[0008] According to a rainwater runoff environment evaluation method according to one embodiment of the present invention, a water collection analysis step calculates a water collection path infiltration amount, which indicates the amount of rainwater that infiltrates into the pavement surface along the water collection path; a green space analysis step calculates a green space infiltration amount, which indicates the amount of rainwater that infiltrates into the green space, and a green space storage amount, which indicates the amount of rainwater collected through the water collection path that flows into the green space and is stored there; and a runoff environment evaluation step calculates a rainwater runoff suppression amount, which indicates the amount of rainwater that is suppressed from running out of the evaluation area based on the water collection path infiltration amount, the green space infiltration amount, and the green space storage amount. Therefore, the rainwater runoff suppression amount is calculated taking into account phenomena such as infiltration and temporary storage of rainwater as it flows over the pavement surface and into the green space, allowing the rainwater runoff suppression effect of utilizing green spaces to be appropriately evaluated.

[0009] Problems, configurations, and effects other than those described above will become apparent from the detailed description of the invention that follows. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an example of a stormwater runoff environment evaluation device 1. FIG. [Figure 2] 1 shows an example of an evaluation target region 2, where (a) is an overall plan view, (b) is an enlarged plan view of part A, and (c) is a cross-sectional view taken along line BB. [Figure 3] 3 is a flowchart showing an example of the operation of the stormwater runoff environment evaluation device 1. [Figure 4] 10 is a flowchart (continuation of FIG. 3) showing an example of the operation of the stormwater runoff environment evaluation device 1. [Figure 5] 10 is an enlarged plan view of part A showing the analysis results by the water catchment analysis unit 111 and the green space analysis unit 112. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] Fig. 1 is a block diagram showing an example of a stormwater runoff environment evaluation device 1 according to this embodiment. Fig. 2 shows an example of an evaluation target area 2, where (a) is an overall plan view, (b) is an enlarged plan view of part A, and (c) is a cross-sectional view along line BB.

[0013] The stormwater runoff environment evaluation device 1 is a device that implements a stormwater runoff environment evaluation method for evaluating the stormwater runoff environment in an evaluation target area 2. The evaluation target area 2 is, for example, an outdoor area that is assumed to be an urban area or residential area, and its shape and area can be set arbitrarily. The evaluation target area 2 may be an area based on an administrative division such as a city, town, or village, the site of a school, factory, commercial facility, public facility, or the like, or an area within a predetermined radius centered on a landmark such as a station or airport.

[0014] As shown in Fig. 2, the area to be evaluated 2 has a paved surface 20 and a green area 21 as its ground surface, and structures 23 such as curbs, gutters, and steps are installed in part of the boundary 22 between the paved surface 20 and the green area 21. In addition, a stormwater drainage system 24 consisting of, for example, a stormwater cistern, drainage pipes, etc. is installed in the area to be evaluated 2. The gutters installed in the boundary 22 may function as part of the stormwater drainage system 24.

[0015] The paved surface 20 is mainly a road portion such as a roadway or a sidewalk, and is paved with a paving material such as asphalt or concrete. The green ground 21 is, for example, a green area such as a green belt or a planting strip created beside a road or a building, and is also called a rain garden. The green ground 21 is distributed throughout the evaluation area 2, and its shape and area are not particularly limited. The green ground 21 is formed in the shape of a depression relative to the surrounding paved surface 20, and a gravel layer 25 having a predetermined depth h1 and porosity may be formed underground.

[0016] When rainwater is generated in the evaluation area 2 due to a predetermined rainfall intensity and duration, the rainwater on impervious surfaces, such as pavement 20, flows over the pavement 20 along a collection path determined by the elevation difference (gradient) of the pavement 20, as shown in FIG. 2(c), and flows into a stormwater drainage system 24, thereby flowing out of the evaluation area 2. In this case, the effective use and installation of green spaces 21 is being considered as one measure to suppress rainwater runoff so that the amount of rainwater does not exceed the treatment capacity of the stormwater drainage system 24. By allowing not only rainwater that falls directly on the green spaces 21 but also a portion of the rainwater that falls on the pavement 20 to flow into the green spaces 21, as shown in FIG. 2(c), the rainwater is infiltrated and temporarily stored in the green spaces 21, thereby suppressing rainwater runoff.

[0017] Therefore, the rainwater runoff environment evaluation device 1 functions as a device that realizes a rainwater runoff environment evaluation method that evaluates the rainwater runoff environment in the above-mentioned evaluation target area 2. In the rainwater runoff environment evaluation device 1 according to this embodiment, a case will be described in which the rainwater runoff amount, which indicates the amount of rainwater runoff, and the rainwater runoff suppression amount, which indicates the amount of rainwater runoff suppressed, are calculated based on the rainwater runoff environment including the collection path infiltration amount, which indicates the amount of rainwater that infiltrates into the pavement surface 20, the green space infiltration amount, which indicates the amount of rainwater that infiltrates into the green space 21, and the green space storage amount, which indicates the amount of rainwater stored in the green space 21.

[0018] The stormwater runoff environment assessment device 1 is configured, for example, by a general-purpose or dedicated computer, etc. Specifically, as shown in Fig. 1, the stormwater runoff environment assessment device 1 includes a storage unit 10 configured by an HDD, an SDD, a memory, etc., a control unit 11 configured by a processor such as a CPU, an MPU, a GPU, etc., an input unit 12 configured by a keyboard, a mouse, a touch panel, etc., an output unit 13 configured by a display, a touch panel, a speaker, etc., a communication unit 14 which is a communication interface with the network, and a device connection unit 15 which is a connection interface with recording media such as a USB memory, a CD-ROM, a DVD, etc., and external devices such as a scanner, a printer, etc.

[0019] The memory unit 10 stores a stormwater runoff environmental assessment program 100 and area data 101 related to the assessment target area 2. The area data 101 is composed of geographic data 102, land cover data 103, land boundary data 104, and stormwater drainage system data 105. Note that part or all of the area data 101 may be stored in a recording medium or an external storage device instead of being stored in the memory unit 10. Also, part or all of the area data 101 may be displayed on a screen by the output unit 13, or may be editable by the input unit 12.

[0020] The geographic data 102 is data that records the three-dimensional shape of the evaluation target area 2 and the land classification of the ground surface (paved surface 20 and green surface 21). As shown in Fig. 2(b), the geographic data 102 records various data in units of meshes M in which the evaluation target area 2 is divided at predetermined intervals in the north-south and east-west directions.

[0021] The three-dimensional shape included in the geographic data 102 includes the position and elevation of each mesh M (elevation of a representative point or average elevation). The elevation may be the elevation including features such as buildings and trees on the ground surface, or the elevation relative to the ground surface without including features. In other words, the geographic data 102 may use a digital elevation model (DEM) or a digital surface model (DSM).

[0022] As the land classification of the ground surface included in the geographic data 102, the classification of the ground surface of each mesh M is recorded, for example, as normal asphalt, permeable asphalt, concrete, green space, etc. Normal asphalt, permeable asphalt, and concrete are land classifications that represent paved surfaces 20. Green space is a land classification that represents green ground 21.

[0023] If a gravel layer 25 having a predetermined depth h1 and porosity is formed in the underground portion of the green ground surface 21, the depth h1 and porosity of the gravel layer 25 for that green ground surface 21 are recorded in the geographic data 102.

[0024] The land cover data 103 is data in which the runoff coefficient and infiltration capacity of the ground surface (paved surface 20 and green surface 21) are recorded by land classification.

[0025] The land boundary data 104 is data that records the installation status of structures 23 installed on the boundary 22 between the paved surface 20 and the green area 21. The land boundary data 104 records the positions, sizes, and shapes of the structures 23, such as curbs, gutters, and steps.

[0026] The stormwater drainage system data 105 is data that records construction drawings of the stormwater drainage system 24 in the evaluation target area 2. The stormwater drainage system data 105 records the positions, sizes, shapes, and connections of the stormwater manholes and drainage pipes that make up the stormwater drainage system 24. If an overflow manhole set to a predetermined flood depth h2 is installed on the green ground 21, the stormwater drainage system data 105 records the flood depth h2 for that overflow manhole.

[0027] The control unit 11 executes the stormwater runoff environment evaluation program 100 to function as an evaluation condition receiving unit 110, a water catchment analysis unit 111, a green space analysis unit 112, a runoff environment evaluation unit 113, and an output processing unit 114. Details of each unit will be described later.

[0028] (Rainwater runoff environmental assessment method) A rainwater runoff environment evaluation method implemented by the rainwater runoff environment evaluation device 1 having the above configuration will be described.

[0029] 3 and 4 are flowcharts showing an example of the operation of the rainwater runoff environment assessment device 1 according to this embodiment. Fig. 5 is an enlarged plan view of part A showing the analysis results by the water catchment analysis unit 111 and the green space analysis unit 112.

[0030] First, in step S100 (evaluation condition receiving step), the evaluation condition receiving unit 110 receives area data 101 (geographical data 102, land cover data 103, land boundary data 104, and storm water drainage system data 105) related to the evaluation target area 2, as well as rainfall conditions (for example, rainfall intensity, rainfall duration, etc.) in the evaluation target area 2. The area data 101 may be prepared in advance and stored in the memory unit 10, or may be received from a recording medium via the device connection unit 15, or may be data on a network received via the communication unit 14. The rainfall conditions may be based on past meteorological observation data, or may be based on anticipated future torrential rains, typhoons, etc.

[0031] Next, in steps S110 to S116 (water collection analysis step), the water collection analysis unit 111 analyzes the water collection environment of the pavement surface 20 based on the area data 101 and rainfall conditions received in step S100.

[0032] Specifically, in step S110, the water collection analysis unit 111 refers to the land classification of each mesh M included in the geographic data 102 and identifies multiple meshes M that make up the pavement surface 20 as the area of ​​the pavement surface 20 within the evaluation target area 2.

[0033] Next, in step S111, the water collection analysis unit 111 analyzes, based on the geographic data 102, the water collection path when rainwater flows over the pavement surface 20 and is collected, and the amount of rainwater collected by the water collection path.

[0034] For example, the water collection analysis unit 111 refers to the position and elevation (geographical data 102) of each mesh M (pavement surface 20) identified in step S110, and identifies the flow direction according to the elevation difference between adjacent meshes M. Then, the water collection analysis unit 111 determines the upstream-downstream relationship according to the flow direction, and links adjacent meshes M together to identify a water collection route (solid arrow in FIG. 5). In this case, not just one water collection route but multiple water collection routes are identified as shown in FIG. 5.

[0035] Furthermore, the water collection analysis unit 111 refers to the land cover data 103 according to the land classification (geographic data 102) of each mesh M (pavement surface 20) identified in step S110, and identifies the runoff coefficient of each mesh M that constitutes the water collection route identified as above. Then, the water collection analysis unit 111 calculates the flow rate in each mesh M by multiplying the precipitation based on the rainfall conditions, the unit area of ​​the mesh M, and the runoff coefficient of the mesh M, and calculates the amount of rainwater collected by the water collection route for each water collection route by accumulating the flow rate for each mesh M along the water collection route.

[0036] Next, in step S112, the water collection analysis unit 111 calculates the water collection path infiltration amount, which indicates the amount of rainwater that flows over the surface along the water collection path and infiltrates into the pavement surface 20. For example, the water collection analysis unit 111 refers to the land cover data 103 in accordance with the land classification (geographic data 102) of each mesh M (pavement surface 20) identified in step S110, and identifies the infiltration capacity of each mesh M that constitutes the water collection path. Then, the water collection analysis unit 111 calculates the infiltration amount in each mesh M based on the unit area of ​​the mesh M and the infiltration capacity of the mesh M, and calculates the water collection path infiltration amount by accumulating the infiltration amounts for each mesh M that constitutes the water collection path.

[0037] Next, in step S113, the water collection analysis unit 111 extracts the contact or intersection points between the water collection route and the outer periphery of the green ground surface 21 based on the geographic data 102, thereby identifying candidate inflow points (white circles and black circles in Figure 5) where rainwater collected via the water collection route flows from the paved surface 20 into the green ground surface 21.

[0038] Next, in step S114, the water collection analysis unit 111 determines, for each water collection route, based on at least one of the land boundary data 104 and the stormwater drainage system data 105, whether there are any obstructing factors that hinder the inflow of rainwater when the rainwater collected through the water collection route is collected from the paved surface 20 to the green surface 21.

[0039] For example, the water collection analysis unit 111 refers to the land boundary data 104 and determines whether or not the above-mentioned obstructing factor exists depending on whether or not a structure 23 such as a curb, a gutter, or a step is installed at a position identified as a candidate for the inflow point. As a result, if the structure 23 is not installed, it is determined that there is no obstructing factor (step S114: No), and if the structure 23 is installed, it is determined that there is an obstructing factor (step S114: Yes). In addition, the water collection analysis unit 111 refers to the stormwater drainage system data 105 and determines whether or not the above-mentioned obstructing factor exists depending on whether or not a stormwater inlet that constitutes the stormwater drainage system 24 is installed at the position of the inflow point. As a result, if the stormwater inlet is not installed, it is determined that there is no obstructing factor (step S114: No), and if the stormwater inlet is installed, it is determined that there is an obstructing factor (step S114: Yes).

[0040] If the water collection analysis unit 111 determines that there is no obstruction factor for the candidate inflow point (step S114: No), then in step S115, the candidate inflow point is set as an inflow point (white circle in FIG. 5) from the paved surface 20 to the green ground surface 21. On the other hand, if the water collection analysis unit 111 determines that there is an obstruction factor for the candidate inflow point (step S114: Yes), then in step S116, the candidate inflow point is set as an outflow point (black circle in FIG. 5) from the paved surface 20 to outside the area.

[0041] Next, in steps S120 to S126 (green space analysis process), the green space analysis unit 112 calculates the green space infiltration amount, which indicates the amount of rainwater that infiltrates into the green space 21, based on the geographic data 102, and calculates the green space storage amount, which indicates the amount of rainwater that is collected through the water collection route and flows into the green space 21 and is stored.

[0042] Specifically, in step S120, the green space analysis unit 112 refers to the land classification of each mesh M included in the geographic data 102 and identifies multiple meshes M that constitute the green space 21 as the area of ​​the green space 21 within the evaluation target area 2.

[0043] Next, in step S121, the green space analysis unit 112 analyzes the green space portions connected to the inflow points (white circles in FIG. 5) set in step S115 and the amount of rainwater flowing into the green space portions from the inflow points (white circles in FIG. 5) based on the geographic data 102. The green space portions have green ground 21 as their ground surface and are portions that correspond to green belts and planted areas distributed throughout the evaluation target area 2. Furthermore, by connecting the green space portions to the inflow points, rainwater collected via the water collection routes determined in step S114 to have no obstructing factors will flow into the green space portions from the pavement surface 20.

[0044] For example, the green space analysis unit 112 refers to the position and altitude (geographical data 102) of each mesh M (green space 21) identified in step S120, and identifies the green space portion according to the difference in elevation between adjacent meshes M. Then, the green space analysis unit 112 identifies the green space portion connected to the inflow point (white circle in FIG. 5) set in step S115 based on the positional relationship between the inflow point and the green space portion. In this case, not just one green space portion but multiple green space portions (in the example of FIG. 5, the left green space portion 26L and the right green space portion 26R) are identified as the green space portion.

[0045] Furthermore, the green space analysis unit 112 calculates the amount of rainwater inflow from an inflow point connected to a green space portion based on the amount of water collected by the collection channels corresponding to the inflow points connected to the green space portion. In this case, if multiple inflow points are connected to a green space portion, the green space analysis unit 112 calculates the amount of rainwater inflow to the green space portion by accumulating the amounts of water collected by multiple collection channels corresponding to the multiple inflow points. In the example of Figure 5, for the left green space portion 26L, the inflow amount to the left green space portion 26L is calculated by accumulating the amounts of water collected by 12 collection channels corresponding to 12 inflow points, and for the right green space portion 26R, the inflow amount to the right green space portion 26R is calculated by accumulating the amounts of water collected by 6 collection channels corresponding to 6 inflow points.

[0046] Next, in step S122, the green space analysis unit 112 refers to the land cover data 103 according to the land classification (geographical data 102) of each mesh M (green space 21) identified in step S120, and identifies the infiltration capacity of each mesh M that constitutes the green space 21. Then, the water catchment analysis unit 111 calculates the infiltration amount in each mesh M based on the unit area of ​​the mesh M and the infiltration capacity of the mesh M, and calculates the green space infiltration amount by accumulating the infiltration amounts for each mesh M that constitutes the green space 21.

[0047] Next, in step S123, the green space analysis unit 112 calculates the maximum storage capacity that can be stored in the green space 21. Based on the flooding depth h2 set for the green space 21, the green space analysis unit 112 calculates a first storage capacity that can be stored on the green space 21 as the maximum storage capacity, and if a gravel layer 25 has been formed below the green space 21, calculates the maximum storage capacity by adding the first storage capacity and a second storage capacity that can be stored in the gravel layer 25.

[0048] For example, the green space analysis unit 112 refers to the flooding depth h2 included in the stormwater drainage system data 105, and multiplies the flooding depth h2 by the unit area of ​​the mesh M to calculate the stored water volume in that mesh M for each mesh M, and calculates the first stored water volume of the green space portion by accumulating the stored water volumes for each mesh M that constitutes the green space 21. Furthermore, if a gravel layer 25 is formed below the green space 21, the green space analysis unit 112 refers to the depth h1 and porosity of the gravel layer 25 included in the geographic data 102, and calculates the stored water volume in that mesh M for each mesh M based on the depth h1 and porosity of the gravel layer 25 and the unit area of ​​the mesh M, and calculates the second stored water volume of the green space portion by accumulating the stored water volumes for each mesh M that constitutes the green space 21. The green space analysis unit 112 then calculates the maximum stored water volume by adding the first stored water volume and the second stored water volume.

[0049] Next, in step S124, the green space analysis unit 112 determines for each green space portion whether the amount of rainwater flowing in from the inflow point identified in step S121 exceeds the maximum storage capacity identified in step S123, causing an overflow.

[0050] If the green space analysis unit 112 determines that the inflow does not exceed the maximum storage volume (step S124: No), it decides in step S125 to treat the inflow as the green space storage volume, and if it determines that the inflow exceeds the maximum storage volume (step S124: Yes), it decides in step S126 to treat the maximum storage volume as the green space storage volume.

[0051] Next, in step S130 (runoff environment evaluation step), the runoff environment evaluation unit 113 calculates a rainwater runoff suppression amount X, which indicates the amount of rainwater that has been suppressed from running off from the evaluation target area 2 to outside the area, based on the water collection route infiltration amount A calculated in step S112, the green space infiltration amount B calculated in step S122, and the green space storage amount C calculated in steps S121, S123 to S126. Specifically, the runoff environment evaluation unit 113 calculates the rainwater runoff suppression amount X (= A + B + C) by adding the water collection route infiltration amount A, the green space infiltration amount B, and the green space storage amount C.

[0052] Next, in step S131 (runoff environment evaluation step), the runoff environment evaluation unit 113 calculates a tentative runoff amount D of rainwater that flows out of the evaluation target area 2 to the outside of the area when it is assumed that rainwater is not collected from the paved surface 20 to the green space 21 via the water collection paths. For example, the runoff environment evaluation unit 113 calculates the tentative runoff amount D of rainwater by accumulating the amounts of water collected by all the water collection paths, assuming that all inflow points from the paved surface 20 to the green space 21 are set as outflow points to the outside of the area. Then, the runoff environment evaluation unit 113 calculates the rainwater runoff amount Y (= DABC), which indicates the amount of rainwater that flows out of the evaluation target area 2 to the outside of the area, by subtracting the water collection path infiltration amount A, the green space infiltration amount B, and the green space storage amount C from the tentative runoff amount D of rainwater.

[0053] Next, in step S140 (output processing step), the output processing unit 114 performs processing to output the evaluation result of the runoff environment by the runoff environment evaluation unit 113. For example, the output processing unit 114 outputs the evaluation result of the runoff environment by displaying the stormwater runoff suppression amount X calculated in step S130 and the stormwater runoff amount Y calculated in step S131 on a screen via the output unit 13 or storing them as data in the memory unit 10.

[0054] The evaluation results of the runoff environment may be output based on, for example, multiple area data 101 or multiple rainfall conditions, thereby evaluating the impact on the runoff environment due to different conditions. For example, when the conditions of the structure 23 are changed by replacing the curb with one having a through-hole to allow rainwater to flow or removing part of the curb to create a gap through which rainwater can flow, the evaluation condition receiving unit 110 may receive the evaluation conditions before and after the change, and the output processing unit 114 may output the evaluation results of the runoff environment before and after the change as processing by the water catchment analysis unit 111, the green space analysis unit 112, and the runoff environment evaluation unit 113, thereby outputting the degree of change (improvement) in the runoff environment. Furthermore, the evaluation results of the runoff environment may be used as evidence for a certification system (e.g., LEED) that evaluates environmental performance.

[0055] As described above, according to the rainwater runoff environment evaluation method realized by the rainwater runoff environment evaluation device 1 of this embodiment, in the water collection analysis step (S110 to S116), a water collection path infiltration amount is calculated, which indicates the amount of rainwater that flows over the pavement surface 20 along the water collection path and infiltrates into the pavement surface 20; in the green space analysis step (S120 to S126), a green space infiltration amount is calculated, which indicates the amount of rainwater that infiltrates into the green space 21, and a green space storage amount is calculated, which indicates the amount of rainwater that is collected via the water collection path and flows into the green space 21 and is stored; and in the runoff environment evaluation step (S130 to S131), a rainwater runoff suppression amount is calculated, which indicates the amount of rainwater that is suppressed from running off from the evaluation target area 2 to outside the area, based on the water collection path infiltration amount, green space infiltration amount, and green space storage amount.

[0056] Therefore, the amount of infiltration of rainwater flowing over the pavement surface 20 along the collection path into the pavement surface 20 is reflected in the rainwater runoff suppression amount, so that, for example, if permeable asphalt is used for the pavement surface 20, the rainwater runoff suppression effect can be quantitatively evaluated. Furthermore, the amount of green space infiltration when rainwater infiltrates into the green surface 21 and the amount of green space storage where rainwater collected via the collection path is stored in the green surface 21 are reflected in the rainwater runoff suppression amount, so that the rainwater runoff suppression effect of using green spaces can be quantitatively evaluated. Therefore, the rainwater runoff suppression amount is calculated taking into account phenomena such as infiltration and temporary storage of rainwater when rainwater flows over the pavement surface 20 and into the green surface 21, so that the rainwater runoff suppression effect of using green spaces can be appropriately evaluated.

[0057] (Other embodiments) Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the technical concept of the present invention.

[0058] For example, in the above embodiment, the water collection analysis unit 111 is described as determining in step S114 whether or not there are any obstructing factors that hinder the inflow of rainwater at the candidate inflow point based on at least one of the land boundary data 104 and the rainwater drainage system data 105. However, the water collection analysis unit 111 may omit the determination in step S114 and treat the candidate inflow point as having no obstructing factors, or may treat the candidate inflow point as having obstructing factors.

[0059] Furthermore, in the above embodiment, the green space analysis unit 112 was described as comparing the amount of rainwater inflow from the inflow point with the maximum storage amount in steps S124 to S126, and determining the green space storage amount based on the results of the comparison, but the green space analysis unit 112 may omit the comparison in step S124 and treat the maximum storage amount as the green space storage amount.

[0060] Furthermore, in the above embodiment, the runoff environment evaluation unit 113 was described as calculating the rainwater runoff amount in addition to the rainwater runoff suppression amount in steps S130 and S131, but the runoff environment evaluation unit 113 may omit either step S130 or S131 and calculate either the rainwater runoff suppression amount or the rainwater runoff amount.

[0061] In the above embodiment, the stormwater runoff environmental assessment program 100 has been described as being stored in the storage unit 10, but it may be provided by being recorded in an installable or executable file on a computer-readable recording medium such as a USB memory, CD-ROM, or DVD. The stormwater runoff environmental assessment program 100 may also be provided by being stored on a computer connected to a network and downloaded via the network. [Explanation of symbols]

[0062] 1...stormwater runoff environmental evaluation device, 2...evaluation area, 10...Memory unit, 11...Control unit, 12...Input unit, 13...Output unit, 14...Communication unit, 15...Device connection part, 20...paved surface, 21...green ground, 22...boundary, 23...structure, 24...gravel layer, 25...stormwater drainage system, 26L, 26R...green areas 100... Stormwater Runoff Environmental Assessment Program, 101... Area Data, 102... Geographic Data, 103...Land cover data, 104...Land boundary data, 105...Storm water drainage system data, 110...Evaluation condition receiving unit, 111...Water catchment analysis unit, 112...Green space analysis unit, 113... outflow environment evaluation unit, 114... output processing unit

Claims

1. A rainwater runoff environment evaluation method for evaluating the rainwater runoff environment in an evaluation target area having a paved surface and a green area as ground surfaces, a water collection analysis process for analyzing the water collection path when the rainwater flows over the pavement surface and is collected based on geographic data that records the three-dimensional shape of the area to be evaluated and the land classification of the ground surface, and calculating the water collection path infiltration amount, which indicates the amount of the rainwater that flows over the surface along the water collection path and infiltrates into the pavement surface; a green space analysis step of calculating a green space infiltration amount indicating the amount of rainwater that infiltrates into the green space based on the geographical data, and calculating a green space storage amount indicating the amount of rainwater that flows into and is stored in the green space after being collected through the water collection route; a runoff environment evaluation step of calculating a rainwater runoff suppression amount, which indicates the amount of rainwater that has been suppressed from running off from the evaluation target area to outside the area, based on the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount; The spill environment assessment step includes: The rainwater runoff amount indicating the amount of rainwater that flows out of the evaluation area to the outside of the evaluation area is calculated in addition to or instead of the rainwater runoff suppression amount by subtracting the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount from the hypothetical outflow amount of rainwater that flows out of the evaluation area to the outside of the evaluation area when it is assumed that the rainwater collected through the water collection route does not flow from the paved surface into the green space. Stormwater runoff environmental assessment methods.

2. A rainwater runoff environment evaluation method for evaluating the rainwater runoff environment in an evaluation target area having a paved surface and a green area as ground surfaces, a water collection analysis process for analyzing the water collection path when the rainwater flows over the pavement surface and is collected based on geographic data that records the three-dimensional shape of the area to be evaluated and the land classification of the ground surface, and calculating the water collection path infiltration amount, which indicates the amount of the rainwater that flows over the surface along the water collection path and infiltrates into the pavement surface; a green space analysis step of calculating a green space infiltration amount indicating the amount of rainwater that infiltrates into the green space based on the geographical data, and calculating a green space storage amount indicating the amount of rainwater that flows into and is stored in the green space after being collected through the water collection route; a runoff environment evaluation step of calculating a rainwater runoff suppression amount, which indicates the amount of rainwater that has been suppressed from running off from the evaluation target area to outside the area, based on the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount; The water collection analysis step includes: Based on at least one of land boundary data that records the installation status of structures installed on the boundary between the paved surface and the green area and storm water drainage system data that records construction drawings of the storm water drainage system in the area to be evaluated, determine for each water collection route whether or not there is an obstructing factor that obstructs the inflow of the rain water collected through the water collection route when the rain water flows from the paved surface into the green area; The green space analysis step includes: calculating the green space storage volume based on the rainwater collected through the water collection route determined to have no obstruction factors; Stormwater runoff environmental assessment methods.

3. The water collection analysis step includes: Analyzing the amount of rainwater collected through the water collection path; The green space analysis step includes: Based on the collected water volume, an inflow volume of the rainwater collected through the water collection path determined to have no obstruction factor is analyzed when the rainwater flows into the green space; Calculating the maximum storage amount that can be stored in the green space; determining whether the inflow rate exceeds the maximum storage rate; If the inflow amount does not exceed the maximum storage amount, the inflow amount is treated as the green space storage amount, and if the inflow amount exceeds the maximum storage amount, the maximum storage amount is treated as the green space storage amount. The method for evaluating a stormwater runoff environment according to claim 2.

4. The green space analysis step includes: calculating a first storage amount that can be stored on the green ground surface as the maximum storage amount based on a flooding depth set on the green ground surface; When a gravel layer is formed under the green surface, the maximum storage amount is calculated by adding the first storage amount and a second storage amount that can be stored in the gravel layer. The method for evaluating a stormwater runoff environment according to claim 3.

5. A rainwater runoff environment evaluation device for evaluating the rainwater runoff environment in an evaluation target area having a paved surface and a green area as ground surfaces, a water collection analysis unit that analyzes the water collection path when the rainwater flows over the pavement surface and is collected based on geographic data that records the three-dimensional shape of the area to be evaluated and the land classification of the ground surface, and calculates the water collection path infiltration amount that indicates the amount of the rainwater that flows over the surface along the water collection path and infiltrates into the pavement surface; a green space analysis unit that calculates a green space infiltration amount indicating the amount of rainwater that infiltrates into the green space based on the geographical data, and calculates a green space storage amount indicating the amount of rainwater that is collected through the water collection route and flows into the green space and is stored; a runoff environment evaluation unit that calculates a rainwater runoff suppression amount that indicates the amount of rainwater that is suppressed from running off from the evaluation target area to outside the area based on the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount; The outflow environment evaluation unit The rainwater runoff amount indicating the amount of rainwater that flows out of the evaluation area to the outside of the evaluation area is calculated in addition to or instead of the rainwater runoff suppression amount by subtracting the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount from the hypothetical outflow amount of rainwater that flows out of the evaluation area to the outside of the evaluation area when it is assumed that the rainwater collected through the water collection route does not flow from the paved surface into the green space. Stormwater runoff environmental assessment device.

6. A rainwater runoff environment evaluation device for evaluating the rainwater runoff environment in an evaluation target area having a paved surface and a green area as ground surfaces, a water collection analysis unit that analyzes the water collection path when the rainwater flows over the pavement surface and is collected based on geographic data that records the three-dimensional shape of the area to be evaluated and the land classification of the ground surface, and calculates the water collection path infiltration amount that indicates the amount of the rainwater that flows over the surface along the water collection path and infiltrates into the pavement surface; a green space analysis unit that calculates a green space infiltration amount indicating the amount of rainwater that infiltrates into the green space based on the geographical data, and calculates a green space storage amount indicating the amount of rainwater that is collected through the water collection route and flows into the green space and is stored; a runoff environment evaluation unit that calculates a rainwater runoff suppression amount that indicates the amount of rainwater that is suppressed from running off from the evaluation target area to outside the area based on the water collection route infiltration amount, the green space infiltration amount, and the green space storage amount; The water collection analysis unit Based on at least one of land boundary data that records the installation status of structures installed on the boundary between the paved surface and the green area and storm water drainage system data that records construction drawings of the storm water drainage system in the area to be evaluated, determine for each water collection route whether or not there is an obstructing factor that obstructs the inflow of the rain water collected through the water collection route when the rain water flows from the paved surface into the green area; The green space analysis unit calculating the green space storage volume based on the rainwater collected through the water collection route determined to have no obstruction factors; Stormwater runoff environmental assessment device.

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