Rainwater storage and infiltration system

Abstract

To provide a rainwater storage and infiltration system comprising a plurality of rainwater storage and infiltration basins, wherein a water storage capacity of each rainwater storage and infiltration basin can be secured.SOLUTION: A rainwater storage and infiltration system 1 comprises: a first rainwater storage and infiltration basin 10A and a second rainwater storage and infiltration basin 10B, which store rainwater W1 while allowing the rainwater W1 to infiltrate into the ground; a catchment pipe 21 that supplies the rainwater W1 falling on a roof 2A of a building 2 to the first rainwater storage and infiltration basin 10A; and a distribution pipe 22 that distributes the rainwater W1 stored in the first rainwater storage and infiltration basin 10A to the second rainwater storage and infiltration basin 10B. The first rainwater storage and infiltration basin 10A comprises an overflow pipe 24 that discharges the stored rainwater W1 when a water level of the stored rainwater W1 exceeds a set water level H2, and the distribution pipe 22 distributes the rainwater W1 stored in the first rainwater storage and infiltration basin 10A to the second rainwater storage and infiltration basin 10B when the water level of the first rainwater storage and infiltration basin 10A is equal to or higher than a distribution water level H1 which is lower than the set water level H2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a stormwater retention and infiltration system. [Background technology]

[0002] Rainwater storage and infiltration areas known as rain gardens are known as a type of green infrastructure technology (see, for example, Patent Document 1). Rainwater storage and infiltration areas temporarily store rainwater and allow the stored rainwater to gradually infiltrate into the ground. Rainwater storage and infiltration areas have a variety of functions, such as mitigating the sudden inflow of rainwater into sewer systems during heavy rainfall, as well as landscaping and improving the thermal environment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-44149 A Summary of the Invention [Problem to be solved by the invention]

[0004] In rainwater storage and infiltration areas, rainwater that falls on the roofs of buildings is collected, ensuring the amount of water stored necessary for landscaping and improving the thermal environment. On the other hand, in rainwater storage and infiltration areas that are located in places where it is difficult to use the rainwater that falls on the roofs of buildings, such as rainwater storage and infiltration areas located far from buildings, the amount of stored water is likely to be insufficient. In such rainwater storage and infiltration areas, it is difficult to fulfill functions such as landscaping and improving the thermal environment. [Means for solving the problem]

[0005] A rainwater storage and infiltration system that solves the above-mentioned problems includes a first rainwater storage and infiltration area and a second rainwater storage and infiltration area that store rainwater while infiltrating it into the ground, a water collection pipe that supplies rainwater that falls on the roof of a building to the first rainwater storage and infiltration area, and a distribution pipe that distributes the rainwater stored in the first rainwater storage and infiltration area to the second rainwater storage and infiltration area, wherein the first rainwater storage and infiltration area has an overflow pipe that drains the stored rainwater when the water level of the stored rainwater is higher than a set water level, and the distribution pipe distributes the rainwater stored in the first rainwater storage and infiltration area to the second rainwater storage and infiltration area when the water level of the first rainwater storage and infiltration area is equal to or higher than a distribution water level that is lower than the set water level. Effect of the Invention

[0006] According to the present invention, in a rainwater storage and infiltration system having a plurality of rainwater storage and infiltration areas, the water storage capacity of each rainwater storage and infiltration area can be secured. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a rainwater storage and infiltration system. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of the rainwater storage and infiltration system when the first rainwater storage and infiltration area has reached the distribution water level. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of the rainwater storage and infiltration system in a state where the first rainwater storage and infiltration area has reached a set water level. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, one embodiment of a rainwater storage and infiltration system will be described with reference to Figs. 1 to 3. [Rainwater storage and infiltration system] As shown in Fig. 1, the rainwater storage and infiltration system 1 includes a first rainwater storage and infiltration area 10A and a second rainwater storage and infiltration area 10B. The first rainwater storage and infiltration area 10A is formed near a building 2. The second rainwater storage and infiltration area 10B is formed at a lower level than the first rainwater storage and infiltration area 10A and farther from the building 2 than the first rainwater storage and infiltration area 10A.

[0009] In the following, when the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B are not distinguished from each other, they will be simply described as the rainwater storage and infiltration area 10. The rainwater storage and infiltration area 10 includes a storage section 11 that stores rainwater W1, and an infiltration section 12 that gradually infiltrates the rainwater W1 in the storage section 11 into the ground. In other words, the rainwater storage and infiltration area 10 has a storage and infiltration function that stores the rainwater W1 while gradually infiltrating the rainwater W1 into the ground.

[0010] The rainwater storage and infiltration system 1 includes a water collection pipe 21. The water collection pipe 21 connects the roof 2A of the building 2 and the first rainwater storage and infiltration area 10A. The water collection pipe 21 supplies rainwater W1 that has fallen on the roof 2A of the building 2 to the storage section 11 of the first rainwater storage and infiltration area 10A.

[0011] The rainwater storage and infiltration system 1 includes a distribution pipe 22. The distribution pipe 22 connects the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B. When the water level of the first rainwater storage and infiltration area 10A is equal to or higher than the distribution water level H1, the distribution pipe 22 distributes the rainwater W1 stored in the first rainwater storage and infiltration area 10A to the storage section 11 of the second rainwater storage and infiltration area 10B. That is, in the rainwater storage and infiltration system 1, the first rainwater storage and infiltration area 10A is located on the upstream side, and the second rainwater storage and infiltration area 10B is located on the downstream side. Note that FIG. 1 illustrates a state in which the water level of the first rainwater storage and infiltration area 10A is lower than the distribution water level H1.

[0012] [Rainwater storage and infiltration area] In the rainwater storage and infiltration area 10, the storage unit 11 is provided in a depression formed by excavating the ground. The storage unit 11 has a quadrangular pyramid shape, for example. Plants may be grown around the storage unit 11.

[0013] The infiltration section 12 is formed by backfilling a recess formed in the bottom of the storage section 11 with a base material (not shown). The infiltration section 12 constitutes a part of the bottom surface of the storage section 11. The base material is, for example, a granular material in which aggregate is coated with humus. The infiltration section 12 has the water retention to store rainwater W1, and also has the permeability to allow the rainwater W1 that cannot be stored to seep into the ground.

[0014] In the rainwater storage and infiltration area 10, the bottom surface and slope of the storage section 11 including the infiltration section 12 are covered with a waterproof sheet (not shown). In the part of the bottom surface of the storage section 11 formed by the infiltration section 12, a part of the waterproof sheet is removed and a infiltration pipe (not shown) is placed. The infiltration pipe has a number of small holes on its side.

[0015] In the rainwater storage and infiltration area 10, the infiltration of rainwater W1 stored in the storage section 11 into the ground is suppressed by a waterproof sheet, and the rainwater W1 infiltrates from the storage section 11 to the infiltration section 12 via the infiltration pipe. The amount of rainwater W1 infiltrating from the storage section 11 to the infiltration section 12 is adjusted by the number of small holes in the infiltration pipe and the size of the small holes. The infiltration pipe is an example of a infiltration amount adjustment section that adjusts the amount of rainwater W1 infiltrating from the storage section 11 to the infiltration section 12.

[0016] Stones 13 are laid on the waterproof sheet covering the storage section 11 and the infiltration section 12. In addition, a gabion (not shown) is placed on the bottom of the storage section 11 above the infiltration pipe. The gabion includes a mesh basket and crushed stones packed into the basket. One example of the gabion is a futon basket. The gabion functions as a filter to prevent the infiltration pipe from being covered with foreign objects such as fallen leaves.

[0017] The rainwater storage and infiltration area 10 includes an adjustment pipe 23 and an overflow pipe 24. The adjustment pipe 23 and the overflow pipe 24 drain the rainwater W1 stored in the storage section 11 to a rainwater basin 30 disposed underground.

[0018] The inlet of the adjustment pipe 23 is disposed near the bottom of the storage section 11. The adjustment pipe 23 drains the rainwater W1 from the bottom of the storage section 11. In the rainwater storage and infiltration area 10, the rainwater W1 starts to be stored when the supply amount of the rainwater W1 is greater than the sum of the infiltration amount from the infiltration section 12 and the drainage amount from the adjustment pipe 23.

[0019] The adjustment pipe 23 is connected to an overflow pipe 24 underground. The adjustment pipe 23 has an orifice (not shown) at the connection portion with the overflow pipe 24. The orifice is a throttling mechanism for adjusting the flow rate of the rainwater W1 drained from the storage section 11 through the adjustment pipe 23.

[0020] When the water level in the storage section 11 is higher than the set water level H2, the overflow pipe 24 drains the rainwater W1 in the storage section 11 into the rainwater basin 30. The set water level H2 is set individually for each rainwater storage and infiltration area 10. In the first rainwater storage and infiltration area 10A, the distribution water level H1 is lower than the set water level H2.

[0021] The set water level H2 is set, for example, to a height equivalent to the planned high water level (HWL) at which the storage unit 11 is filled with water. The planned high water level is set to a height lower than the top of the storage unit 11 so that the rainwater W1 does not overflow even when the storage unit 11 is filled with water.

[0022] The rainwater storage and infiltration system 1 includes a rainwater manhole 30. The rainwater manhole 30 stores rainwater W1 drained from the storage section 11 through the adjustment pipe 23 and the overflow pipe 24. The rainwater W1 stored in the rainwater manhole 30 may be drained as sewage or may be used as general purpose water.

[0023] In addition, Figure 1 illustrates a configuration in which the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B each drain into a separate rainwater manhole 30, but the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B may share a single rainwater manhole 30.

[0024] [Flow of rainwater during rainfall] Hereinafter, the flow of rainwater during rainfall in the rainwater storage and infiltration system 1 will be described with reference to Figures 1 to 3. Figure 2 illustrates a state in which the water level of the first rainwater storage and infiltration area 10A is equal to or higher than the distribution water level H1 and equal to or lower than the set water level H2. Figure 3 illustrates a state in which the water levels of the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B are higher than the set water level H2.

[0025] As shown in Fig. 1, at the start of rainfall, the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B store rainwater W1 that has fallen directly onto the storage section 11 of each rainwater storage and infiltration area 10. In addition, the first rainwater storage and infiltration area 10A is supplied with rainwater W1 that has fallen onto the roof 2A of the building 2 through a water collection pipe 21.

[0026] When the supply of rainwater W1 to each rainwater storage and infiltration area 10 becomes greater than the sum of the infiltration amount from the infiltration section 12 and the drainage amount from the adjustment pipe 23, the water level of the storage section 11 rises. When the water level of the storage section 11 becomes higher than the stone 13 arranged at the bottom of the storage section 11, the rainwater W1 stored in the storage section 11 becomes visible.

[0027] From the viewpoint of landscaping, it is preferable that the rainwater W1 stored in the storage section 11 is visible, for example, at least 50 days per year (approximately once every 7 days). For example, the frequency at which the rainwater W1 stored in the storage section 11 is visible can be adjusted by setting the supply capacity (e.g., catchment area), infiltration capacity, and drainage capacity of the rainwater W1 according to the volume of the storage section 11 based on statistics on past precipitation for each region.

[0028] As shown in Fig. 2, when the water level of the first rainwater storage and infiltration area 10A becomes equal to or higher than the distribution water level H1, the rainwater W1 stored in the first rainwater storage and infiltration area 10A is supplied to the second rainwater storage and infiltration area 10B through the distribution pipe 22. As a result, the water level rises gradually in the first rainwater storage and infiltration area 10A, while the water level rises more rapidly in the second rainwater storage and infiltration area 10B. Therefore, the supply amount of rainwater W1 is equalized between the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B.

[0029] As shown in Fig. 3, when the water level of the rainwater storage and infiltration area 10 becomes higher than the set water level H2, the rainwater W1 stored in the rainwater storage and infiltration area 10 is drained into the rainwater basin 30 through the overflow pipe 24. This prevents the rainwater W1 from overflowing from the rainwater storage and infiltration area 10. From the viewpoint of landscaping, it is preferable that the storage section 11 is filled with water on more than 30 days per year.

[0030] 1 to 3, the water level decreases until the storage section 11 is empty due to seepage from the infiltration section 12 and drainage from the adjustment pipe 23. At this time, if the maximum retention time from when the rain stops when the water level of the storage section 11 is in a full water state where it has reached the set water level H2 (see FIG. 3) until the storage section 11 is empty is too long, algae and pests may grow in the rainwater storage and infiltration area 10. Therefore, the maximum retention time is preferably within 48 hours, and more preferably within 24 hours.

[0031] As an example, in each rainwater storage and infiltration area 10, the maximum retention time can be adjusted to any length by setting the amount of water discharged per hour from the adjustment pipe 23 according to the amount of water stored when full and the amount of infiltration per hour from the infiltration section 12.

[0032] [Operation of the embodiment] During rainfall, the first rainwater storage and infiltration area 10A receives rainwater W1 that has fallen on the roof 2A of the building 2 through a collection pipe 21. The second rainwater storage and infiltration area 10B distributes the rainwater W1 from the first rainwater storage and infiltration area 10A through a distribution pipe 22. Therefore, the rainwater W1 that has fallen on the roof 2A of the building 2 is also distributed in the second rainwater storage and infiltration area 10B.

[0033] [Effects of the embodiment] According to the above embodiment, the following effects can be obtained. (1) Rainwater W1 that falls on the roof 2A of the building 2 is supplied to the first rainwater storage and infiltration area 10A via the collection pipe 21, and the rainwater W1 in the first rainwater storage and infiltration area 10A is supplied to the second rainwater storage and infiltration area 10B via the distribution pipe 22. This allows the rainwater W1 that falls on the roof 2A of the building 2 to be distributed not only to the first rainwater storage and infiltration area 10A but also to the second rainwater storage and infiltration area 10B. Therefore, a sufficient amount of water can be stored in each rainwater storage and infiltration area 10 in the rainwater storage and infiltration system 1.

[0034] (2) By locating the second rainwater storage and infiltration area 10B at a lower elevation than the first rainwater storage and infiltration area 10A, the difference in elevation can be utilized to distribute rainwater W1 from the first rainwater storage and infiltration area 10A to the second rainwater storage and infiltration area 10B.

[0035] (3) The second rainwater storage and infiltration area 10B is provided in a location farther from the building 2 than the first rainwater storage and infiltration area 10A. Even in such a case, with the configuration of this embodiment, the rainwater W1 that falls on the roof 2A of the building 2 can be distributed to the second rainwater storage and infiltration area 10B.

[0036] (4) In addition to infiltration from the infiltration section 12, drainage from the regulating pipe 23 prevents the rainwater W1 from staying in the storage section 11 for a long period of time. This makes it possible to suppress the growth of algae and pests in the rainwater storage and infiltration area 10.

[0037] (5) Placing a gabion on the top of the infiltration pipe can prevent the pipe from being blocked by foreign objects such as fallen leaves. In this way, by using the gabion as a filter for the infiltration pipe, the above effects can be achieved without damaging the scenery.

[0038] [Example of change] The above embodiment can be modified as follows. The modifications can be combined as appropriate within the scope of the present invention.

[0039] The second rainwater storage and infiltration area 10B is provided at a lower elevation than the first rainwater storage and infiltration area 10A. However, the present invention is not limited to this. For example, the second rainwater storage and infiltration area 10B may be provided at the same height as the first rainwater storage and infiltration area 10A or at a higher elevation than the first rainwater storage and infiltration area 10A. In this case, for example, the rainwater W1 in the first rainwater storage and infiltration area 10A may be pumped up by a pump or the like and supplied to the second rainwater storage and infiltration area 10B.

[0040] The second rainwater storage and infiltration area 10B is provided at a location farther from the building 2 than the first rainwater storage and infiltration area 10A. However, this is not limited to the above. For example, regardless of the distance between the building 2 and the second rainwater storage and infiltration area 10B, if it is difficult to directly connect the water collection pipe 21 from the building 2 to the second rainwater storage and infiltration area 10B, the storage capacity of the second rainwater storage and infiltration area 10B can be secured by adopting the configuration of this embodiment. Therefore, the second rainwater storage and infiltration area 10B may be located at a distance from the building 2 that is approximately the same as that of the first rainwater storage and infiltration area 10A, or may be located closer than the first rainwater storage and infiltration area 10A.

[0041] In the rainwater storage and infiltration area 10, if the maximum retention time can be set to a suitable length only by the infiltration amount from the infiltration section 12, the adjustment pipe 23 may be omitted. For example, the adjustment pipe 23 may be provided in only one of the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B, or the adjustment pipe 23 may be omitted in both the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B.

[0042] The gabion provided at the top of the infiltration pipe may be omitted. Also, other filters may be used instead of the gabion. The number of gabions is not limited, and for example, a gabion may be placed near the inlet of the adjustment pipe 23. The above modification may be applied to only one of the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B, or to both.

[0043] Although a seepage pipe has been given as an example of the seepage amount adjustment section, the present invention is not limited thereto, and the seepage amount adjustment section may be configured to adjust the amount of rainwater W1 that seeps from the storage section 11 to the seepage section 12. The seepage amount adjustment section may be omitted. The above modification may be applied to only one of the first rainwater storage and seepage area 10A and the second rainwater storage and seepage area 10B, or to both.

[0044] In the rainwater storage and infiltration area 10, a configuration in which the rainwater W1 in the storage section 11 is infiltrated into the ground from the infiltration section 12 has been exemplified. Alternatively, at least one of the first rainwater storage and infiltration area 10A and the second rainwater storage and infiltration area 10B may be provided with a filtration section for filtering the rainwater W1 instead of the infiltration section 12, and a rainwater collection section for collecting the rainwater W1 that has infiltrated the filtration section. With this configuration, the rainwater W1 whose water quality has been improved by the filtration section is collected by the rainwater collection section, so that the collected rainwater W1 can be reused as it is as miscellaneous water, etc. In other words, the rainwater storage and infiltration area 10 can also serve as a purification facility for using the rainwater W1 as miscellaneous water.

[0045] There is no limitation on the number of water collection pipes 21. For example, a plurality of water collection pipes 21 may be used to supply rainwater W1 from the roofs 2A of a plurality of buildings 2 to the first rainwater storage and infiltration area 10A. The number of distribution pipes 22 is not limited. For example, the first distribution pipe 22 may distribute the rainwater W1 of the first rainwater storage and infiltration area 10A to the second rainwater storage and infiltration area 10B, and the second distribution pipe 22 may distribute the rainwater W1 of the first rainwater storage and infiltration area 10A to another rainwater storage and infiltration area 10. Also, for example, the second distribution pipe 22 may distribute the rainwater W1 of the second rainwater storage and infiltration area 10B to another rainwater storage and infiltration area 10.

[0046] [Note] According to the above embodiment and its modifications, the following technical ideas can be derived. (Appendix 1) A first rainwater storage and infiltration area and a second rainwater storage and infiltration area each having a storage section for storing rainwater and an infiltration section for infiltrating the rainwater from the storage section into the ground; A water collection pipe that supplies rainwater that falls on the roof of a building to the first rainwater storage and infiltration area; A distribution pipe that distributes the rainwater stored in the first rainwater storage and infiltration area to the second rainwater storage and infiltration area, The first rainwater storage and infiltration area is provided with an overflow pipe that drains the stored rainwater when the water level of the stored rainwater is higher than a set water level, The distribution pipe distributes the rainwater stored in the first rainwater storage and infiltration area to the second rainwater storage and infiltration area when the water level of the first rainwater storage and infiltration area is equal to or higher than a distribution water level which is lower than the set water level, At least one of the first rainwater storage and infiltration area and the second rainwater storage and infiltration area is provided with an adjustment pipe that drains the rainwater stored from the bottom of the storage area. Rainwater harvesting infiltration system.

[0047] According to the above-mentioned supplementary note 1, in addition to infiltration from the infiltration section, drainage from the adjustment pipe can prevent rainwater from staying in the storage section for a long time. This can suppress the growth of algae and pests in the rainwater storage and infiltration area.

[0048] (Appendix 2) At least one of the first rainwater storage and infiltration area and the second rainwater storage and infiltration area is A permeation amount adjustment unit that adjusts the amount of rainwater that permeates from the storage unit to the permeation unit; A gabion arranged on the upper part of the permeation amount adjustment part. A stormwater retention and infiltration system as described in Appendix 1.

[0049] According to the above-mentioned supplementary note 2, the gabion functions as a filter for the infiltration rate adjustment section, thereby preventing the infiltration rate adjustment section from being blocked by foreign objects such as fallen leaves. In addition, by using the gabion as a filter, the above-mentioned effect can be achieved without spoiling the scenery. [Explanation of symbols]

[0050] H1...distribution water level, H2...set water level, W1...rainwater, 1...rainwater storage and infiltration system, 2...building, 2A...roof, 10...rainwater storage and infiltration area, 10A...first rainwater storage and infiltration area, 10B...second rainwater storage and infiltration area, 11...storage section, 12...infiltration section, 13...stone, 21...collection pipe, 22...distribution pipe, 23...adjusting pipe, 24...overflow pipe, 30...rainwater manhole.

Claims

1. A first rainwater storage and infiltration area and a second rainwater storage and infiltration area that store rainwater and infiltrate the rainwater into the ground; A water collection pipe that supplies rainwater that falls on the roof of a building to the first rainwater storage and infiltration area; A rainwater storage and infiltration system comprising: a distribution pipe for distributing rainwater stored in the first rainwater storage and infiltration area to the second rainwater storage and infiltration area; The first rainwater storage and infiltration area is provided with an overflow pipe that drains the stored rainwater when the water level of the stored rainwater is higher than a set water level, The distribution pipe distributes the rainwater stored in the first rainwater storage and infiltration area to the second rainwater storage and infiltration area when the water level of the first rainwater storage and infiltration area is equal to or higher than a distribution water level which is lower than the set water level. Rainwater harvesting infiltration system.

2. The second rainwater storage and infiltration area is provided at a lower level than the first rainwater storage and infiltration area. The storm water retention and infiltration system of claim 1.

3. The second rainwater storage and infiltration area is provided at a location farther from the building than the first rainwater storage and infiltration area. A rainwater storage and infiltration system according to claim 1 or 2.

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