JPH0428328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terrace revetment structure that can restore the ecosystem and purify water, allowing people to enjoy the waterfront.

[Prior Art] In recent years, terrace seawalls have been developed in various places that allow people to get closer to the natural environment on rivers or coastal waters.

Conventional terrace seawalls were constructed by driving steel sheet piles all along the water's edge, filling the inside with earth, and forming a promenade on top.

[Problems to be Solved by the Invention] For example, the current situation is that on the downstream side of urban rivers, conditions are not suitable for fish to live due to water pollution caused by industrial wastewater, domestic wastewater, etc.

In particular, such polluted waters have extremely poor transparency, making it difficult for light to reach the bottom of the water, making it difficult for photosynthesis to take place, and only poor plants can grow there.
Moreover, since photosynthesis in plants is not active, little oxygen is obtained through this process, and oxygen is consumed by oxidation of pollutants, resulting in an extremely low amount of dissolved oxygen.

Incidentally, in recent years, the development of artificial fish reefs as a type of marine civil engineering has been active, and many proposals have been made regarding this (Utility Model Publication No. 58-155966, Japanese Patent Application Publication No. 1983-15596).
-12922, JP-A-60-196133, JP-A-61-88831,
JP-A-62-32830, JP-A-63-207335, etc.). In many of these, in order to compensate for the decline in fish living in the ocean due to overfishing, structures that make up fish reefs are constructed by having a volumetric space that allows fish to enter the ocean, where habitat conditions are suitable according to the natural environment. It was designed for efficient fish farming.

Therefore, even if a conventional fish reef structure with only living space elements for fish is placed near the terrace seawall in an environment where the habitat conditions for fish are not suitable as described above, it will not be possible to prevent fish from entering urban rivers. It was impossible to recall him.

Therefore, the purpose of the present invention is to solve the above-mentioned conventional problems and promote the photosynthesis of plants and increase the amount of dissolved oxygen in the water area below the terrace seawall where humans can enjoy the waterside. To provide a terrace revetment structure capable of restoring the system and purifying water quality.

[Means for Solving the Problems] The present invention provides a terrace revetment formed to extend horizontally above the water area from the revetment, and a terrace revetment that supports the overhanging end side of the terrace revetment, is fixed to the bottom of the water area, and has a wave-dissipating function. A support structure for a terrace seawall having a structure, a fish nest structure disposed in a water area between the sea wall and the support structure, and a gas containing at least O ₂ from an aeration pipe supported by the fish nest structure. A terrace seawall structure is constructed by providing an air diffuser that blows out air, and an optical fiber that receives natural light or light from a light source from one end and emits the light from the other end that is supported by the fish nest structure. .

[Operation] First, in the terrace revetment structure of the present invention, the terrace revetment is formed by overhanging the water area above the revetment without filling the water's edge with earth, so it does not narrow the water area and reduces the width of rivers that are particularly prone to flooding. There is no narrowing.

In addition, it is possible to restore the ecosystem in the water area below the terrace seawall. That is, in the present invention, an optical fiber is incorporated into a fish nest structure placed in a water area below a terrace seawall, and sunlight as natural light incident from one end of the optical fiber or light from another light source is transmitted underwater through the optical fiber. and promote photosynthesis in plants.

In other words, such polluted waters are rich in plant nutrients (such as nitrogen and phosphorus), so photosynthesis can be activated as long as light is supplied.

As a result of such promotion of photosynthesis, it is possible to promote the reproduction of sessile algae or floating phytoplankton, increase the number of zooplankton that eat them, and secure the above plants or zooplankton as food for fish. I can do it.

Furthermore, in order to solve the problem of a decrease in the amount of dissolved oxygen, which is one of the indicators of water pollution, the present invention incorporates an air diffuser into the fish nest structure and performs aeration using this air diffuser. There is. Here, if there is a flow of water such as a river, or if waves are generated due to navigation of a ship, etc., even if you simply perform aeration with an air diffuser, there will be no air flow near the air diffuser. ₂ flows out as bubbles before being dissolved in the water, making it impossible to increase the amount of dissolved oxygen in the fish nest space. Therefore, in the present invention, aeration is performed by the air diffuser in the quiet region between the seawall and the wave-dissipating structure, thereby increasing the amount of dissolved oxygen in the water area below the terrace seawall.

As mentioned above, by promoting photosynthesis, plants are propagated to secure food for fish, and the amount of dissolved oxygen in the water area is increased, ensuring habitat conditions for fish and restoring the ecosystem. It becomes possible.

Furthermore, as a result of the propagation of photosynthetic plants, the food chain can be promoted, so pollutants can be removed, and aerobic microorganisms can be propagated, so water quality can be purified.

In this way, it is possible to purify the water quality of the water area below the terrace seawall, restore the ecosystem, and create an environment where people can get closer to the water.

[Example] Hereinafter, an example in which the present invention is applied to a terrace revetment structure arranged on the bank of an urban river will be specifically described with reference to the drawings.

FIG. 1 is a schematic sectional view showing a terrace revetment structure, which is an example of the present invention, arranged on a riverbank, FIG. 2 is a schematic perspective view thereof, and FIGS. 3A and B are plan views of a fish nest structure. FIG.

In FIG. 1, a terrace revetment 3 is provided that extends horizontally above a water area from one revetment 2 of a river 1 that flows from the front side to the back side of the drawing. Note that a part of this terrace seawall 3 is made of tempered glass 3a. Further, a support structure 4 is provided which supports the overhanging side of the terrace seawall 3 and is vertically fixed to the riverbed of the river 1.
The support structure 4 is a pile-type structure having a wave-dissipating function by fixing a transparent wall as illustrated in FIGS. 6A and 6B. In the structure shown in FIG. 6A, for example, a plurality of horizontal plates 4b are fixed at a predetermined interval above two stakes 4a. The one shown in FIG.
c is fixed, and a large number of holes 4 are formed in this vertical wave-dissipating plate 4c.
d was formed. In either case, the overhanging end side of the terrace revetment 3 can be supported at the upper end of the pile.

On the other hand, facing the bank 2 of the river 1, the fish nest structure 1
0 is placed. This fish nest structure 10 supports the inner end of the terrace seawall 3 and has a partition wall 12 that partitions a water area from a promenade 44, which will be described later.

In order to form a fish nest space below the terrace seawall 3, this partition wall 12 has a lower terrace 14 that extends from the lower end of the partition wall 12 so as to come into contact with the riverbed, and a lower terrace 14 that extends above this to form a fish nest space. An upper terrace 16 with a short overhang length is provided.

A plurality of culture vessels 40 for culturing adherent algae are provided between the lower terrace 14 and the upper terrace 16 of the fish nest structure 10.

The incubator 40 has, for example, a cylindrical liquid-tight structure, is filled with air, and has an optical fiber 30 inserted therein and supported therein. This incubator 40 is preferably cloudy rather than transparent. In order to efficiently cultivate phytoplankton, a heater 42 with a thermostat is attached to the side surface of the partition wall 12 to maintain the ambient temperature of the culture vessel 40 at, for example, 20°C to 25°C.

Note that, as shown in FIG.
In the area of the partition wall 12 where the upper terrace 16 is not provided, a tempered glass 12a forming a window through which the inside of the water body can be viewed from the promenade 44 is arranged.

The fish nest structure 10 as described above has a width w, for example.
(See Figure 3) is formed several meters long, and by arranging a large number of such fish nest structures 10, an artificial fish reef is formed along the seawall 2 over a length of, for example, 250 meters. .

In addition, when arranging such a fish nest structure 10 on a river bank, as shown in FIG.
It is preferable to stack stones 52 on the lower and upper terraces 14 and 16 of 0, or to plant perennial plants such as reeds (reeds) 54 particularly on the upper terrace 16 as shown in FIG.

Next, a system for supplying light to the fish nest structure 10 will be described with reference to FIG. 4 as well.

This light supply system is composed of a light condensing device 31 shown in FIG. 1 and an optical fiber 30.

The condensing device 31 has a large number of Fresnel lenses 34 supported by a curved arm 33, and the Fresnel lenses 34 are swingable with respect to the curved arm 33 by a motor (not shown). Further, the fulcrum shaft 33a of the curved arm 33 is rotatable by a motor (not shown), and as a result, the Fresnel lens 34 can be directed in the direction of sunlight irradiation.

One end of the optical fiber 30 is arranged at the light focusing position of each Fresnel lens 34, so that the light focused by the Fresnel lens 34 is incident thereon. Note that the Fresnel lens 34 is
When sunlight passes through the lens, the refractive index differs depending on its wavelength. As shown in FIG. 5, the position of one end of the optical fiber 30 is set at a position where visible light rays are focused, and light of other wavelengths, such as ultraviolet rays and infrared rays, does not enter the one end of the optical fiber 30. It's becoming like that.

As described above, this condensing device 31 has a structure that follows the position of the sun, but its control is performed by calculating the position of the sun based on the year, month, and time indicated by the built-in clock mechanism, and based on this result. fresnel lens 34
so that it moves in the direction of the sun. In addition,
A solar position detection optical sensor 35 is disposed inside the transparent dome 32, and when direct sunlight is coming out, this sensor 35 detects the exact position of the sun and determines the movement position of the Fresnel lens 34. It is now controlled by interrupts.

The optical fiber 20 taken out from the light condensing device 31 is extended along the seawall 2 as shown in FIG. 1
6 is inserted into the incubator 40 from the lower surface thereof. Note that the configuration in which the optical fiber 30 is inserted into the incubator 40 in this way is disclosed in
Optical radiators disclosed in Japanese Utility Model Application No. 1723, Japanese Utility Model Application No. 59-194706, and Japanese Utility Model Application No. 60-130403 can be employed.

Next, a configuration for ensuring the amount of dissolved oxygen in the water area of the terrace seawall 3 will be described.

In this embodiment, an aeration pipe 20 is arranged outside the culture vessel 40 on the lower terrace 14. This air diffuser 20 has holes 2 at predetermined intervals in its longitudinal direction.
0a (see Figure 3)), and from this hole 20a
It blows out a gas containing O ₂ , such as air.
One end of this aeration pipe 20 is connected to a first pipe 22 buried in the lower terrace 14 and partition wall 12 of the fish nest structure 10, and one end of this first pipe 22 is connected to a second pipe 22 via a joint 24. The second pipe 26 is connected to a blower device 28, and one end of this second pipe 26 is connected to a blower device 28.
is connected to. The air diffuser 20, the first and second pipes 22, 26, the joint 24, and the blower device 28 are examples of the air diffuser of the present invention.

In addition, in order to ensure that DO (dissolved oxygen content) exceeds a certain value, which is a habitat condition for fish, regardless of changes in DO (dissolved oxygen content) over time or seasonal changes,
A DO sensor 29 is arranged on the side of the area facing the fish nest space, and the output line of this DO sensor 29 is connected to the blower control system of the blower device 28.

Here, in this example, air ration is carried out using the above-mentioned air diffuser in a 250m area along the seawall 2, and the DO in this area is ensured to be above a certain value, which is the habitat condition for fish. In order to
The blower device 28 has a rating of 45KW.
It has equipment with a total capacity of 45KW.

In addition, as described above, the seawall 2 is provided with a promenade 44 whose path is lower than the water surface of the water body below the terrace seawall 3. This makes it possible to visually see the inside of the water area.

Next, the operation of the terrace revetment structure described above will be explained.

In general, the requirements for a fishing reef are that it must have a living spatial element for fish, that is, a volumetric space that fish can enter, and by creating such a space, there is an escape effect that allows fish to escape; It can have a shading effect to avoid seeing through from the outside, and in the case of this embodiment, the fish nest structure 1
The living space for such fish can be guaranteed by the lower terrace 14 and upper terrace 16 of 0. Furthermore, by arranging such a structure inside a river, an eddy current is generated, and since fish prefer such an eddy current, it is possible to have a fish-attracting effect.

In addition to the above-mentioned effects, promoting the effect of food for fish is also necessary as a condition for a fish nest, and securing food for fish is especially difficult in highly polluted rivers 1 to satisfy habitat conditions. This has become a major issue.

The advantage of the terrace revetment structure of this example is that in addition to ensuring the above-mentioned living space for fish, which is a requirement for a general fish nest, it also provides food for the fish and improves the ecosystem. It is at the point where it is possible to recover.

In order to restore the ecosystem in such contaminated waters, it is necessary to create a food chain.

The food chain is a cycle consisting of producers, consumers, and reducers as shown below.

(Producers) (Primary consumers) Abasics → Photosynthetic plants → Rotifers, Crustaceans → (Secondary consumers) Fish → Organic matter → (Reducers) Bacteria → And, especially important, producers It is the existence of photosynthetic plants that are the Of these, securing light is an absolute requirement in contaminated waters.

Therefore, in this embodiment, sunlight is collected by a light collecting device 31 having a Fresnel lens 34 that follows the position of the sun, and visible light necessary for growing plants is made to enter one end of an optical fiber 30. ing. This optical fiber 30 is connected to each fish nest structure 10.
The light is then transmitted to the inside of the adherent algae culturing vessel 40.

Here, in this embodiment, since the light transmission from the condensing device 31 to the fish nest structure 10 is realized by the flexible optical fiber 30, the light can be reliably transmitted no matter what route is routed. Compared to a method in which a plurality of reflecting mirrors are combined, there is no need to place restrictions on the installation position of the condensing device 31, and maintenance is not required, making it easy to implement.

With the above configuration, by irradiating light into the incubator 40, the light diffused by the air inside is emitted from the cloudy white outer surface of the incubator 40 as relatively gentle light. By optimizing this amount of light for photosynthesis of plants, adherent algae grow on the entire outer surface of each culture vessel 40.
On the other hand, floating phytoplankton will be cultured in a relatively quiet area in the wave-dissipating structure 4 around the incubator 40.

In particular, the attached algae culture vessel 40 placed in the living space of fish can attract fish by irradiating it with gentle light, and the fish that prefer this type of algae as food are By eating these, it becomes possible to gradually grow new attached algae.

These plankton and plants act as producers in the above-mentioned plant chain, so they breed zooplankton, which is the primary consumer, and as a result, secure food for the fish, which are the secondary consumers. be able to.

As described above, in this embodiment, even if the river is heavily polluted, the ecosystem can be restored by irradiating the water area with light using the optical fiber 30. Similar effects can be achieved even in places that are not exposed to direct light.

Here, a decrease in dissolved oxygen (DO) has been pointed out as one of the indicators of water pollution in urban rivers.
The terrace revetment structure of this embodiment can maintain the amount of dissolved oxygen that can ensure habitat conditions in the living space for such fish, in addition to meeting the requirements for a general fish nest and feeding effect as described above.

That is, by driving the blower device 28, the compressed air output from this device 28 is
is supplied to the diffuser pipe 20 located in a relatively quiet area between the seawall 2 and the partition wall 12 through the pipe 26, the joint 24, and the first pipe 22,
A large number of holes 20a are formed in the diffuser pipe 20 to blow out oxygen-containing gas into the quiet area. The gas ejected from the diffuser pipe 20 will dissolve into the water in this area while circulating.
Due to the presence of the support structure 4, even if this river 1
Even if waves are generated by ships or the like, or if there is a certain current velocity in the river 1 itself, the inside of the support structure 4 will not be affected by the waves or current velocity as described above. Since it is possible to maintain a comparatively quiet state without any turbulence, it is possible to efficiently dissolve oxygen into the water in this region. Further, such aeration allows water circulation in the water area within the support structure 4.

Here, the lower limit of the amount of dissolved oxygen as a habitat condition for fish is required to be about 3 mg/, but in this embodiment, the DO sensor 29 is placed at a position facing the fish nest space, and this output is sent to the blower. device 28
The blower device 28 is driven and controlled so that the output value of the DO sensor 29 always maintains the amount of dissolved oxygen, which is the lower limit of the habitat conditions. Note that the amount of dissolved oxygen can also be increased as a result of the above-mentioned photosynthesis.

In this way, if it becomes possible to maintain a certain feeding effect in the fish nest space and also secure the amount of dissolved oxygen,
Even if carp, crucian carp, etc. are released into a river 1 where water quality is severely polluted, they will be able to live in the fish nest space, and it will be possible to bring fish back to the urban river, thereby restoring the ecosystem. I can do it.
In addition, by ensuring the above-mentioned plant chain,
It can remove pollutants in water bodies, and by increasing the amount of dissolved oxygen, aerobic microorganisms can propagate and purify water.

By stacking stones 52 on the lower terrace 14 and upper terrace 16 as shown in FIG. 2, for example, it becomes possible to grow plant plants such as moss or algae on the surface of the stones 52. It is also possible to enhance the fish gathering effect.

In addition, as shown in Figure 7, when reeds 54 are grown on the upper terrace 16, these plants absorb nitrogen _N2 or phosphorus P, which are pollutant components that are always present in domestic wastewater. This property makes it possible to promote water purification. In other words, it is said that the above plants absorb 1.2 mg of N ₂ and 0.09 mg of P per day on average, and by growing a large number of such plants in a fish nest structure, water purification can be achieved. can be promoted.

Furthermore, since the above-mentioned plants grow to a height of about 2 m, it is possible to ensure the escape effect of small fish by getting between these plants.

In this embodiment, the terrace seawall 3 is formed to extend above the water area where plants can propagate and the ecosystem can be restored as described above. In this way, since the terrace revetment 3 is formed above the water area, it is possible to form the terrace revetment 3 that allows people to get close to the waterside without particularly narrowing the width of the river 1. Also, the overhanging end side of the terrace revetment 3 can be provided with a support structure. By supporting it with the body 4, it can also perform the supporting function of the river 1. Moreover, by making a part of the terrace seawall 3 made of tempered glass 3a, the ecosystem below can be observed while walking.

Furthermore, by forming a promenade 44 that is lower than the water surface of the water body on the outside of the bulkhead 12 on the side of the seawall 2, and by making a part of the bulkhead 12 made of tempered glass 12a, this promenade 44 can be used as a real river aquarium. can become more familiar with the natural environment of the waterside.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention.

For example, as the fish nest structure 10 installed below the terrace seawall 3, various shapes that can form a fish nest space can be adopted, and the position of the optical fiber 30 arranged in this fish nest structure 10 can be adopted. , air diffuser 22
Various modifications are also possible regarding the position of .

In particular, if the artificial fish reef disclosed in the patent application (1) filed by the applicant dated the same date as the present application is adopted as the fish nest structure position 0, it becomes possible to efficiently cultivate attached algae and phytoplankton. , it becomes possible to easily restore the ecosystem to the water area below the terrace seawall 3.

Furthermore, the present invention is not necessarily limited to artificial reefs placed on the banks of urban rivers, but can be similarly applied to lakes, ponds, bays, etc., and can restore ecosystems even when placed in areas with significant water pollution. It is possible to create an environment where humans can enjoy the waterside, which can promote water purification in this area.

Regarding the light guided by the optical fiber 30, one that uses sunlight is superior in that it can utilize natural energy, but it is also possible to use light from a light source or switch between sunlight and light source. It may be something that you do.

[Effects of the Invention] As explained above, according to the present invention, a terrace revetment is provided without narrowing the water area, and in the water area below the terrace revetment, living space is In addition to the elements, by supplying light with optical fibers and spewing out O ₂ , photosynthesis can be promoted even in highly polluted waters where light cannot reach the water, and the feeding effect is increased by the reproduction of plants. It is also possible to increase the amount of dissolved oxygen in this region. Therefore, it is possible to restore the ecosystem to the water area below the terrace seawall and create an environment where people can enjoy the waterside.
In addition, by creating a plant chain, it is possible to promote water purification.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing an example of a terrace revetment structure arranged on a river revetment, Fig. 2 is a schematic perspective view of the terrace revetment structure, and Fig. 3 A and B are plan views of a fish nest structure. , a cross-sectional view, and FIG. 4 is a schematic front view showing an example of a condensing device. FIG. 6A and B are schematic explanatory diagrams for explaining an example of a wave-dissipating structure, and FIG. 7 is a
FIG. 2 is a schematic cross-sectional view showing a state in which reed plants are grown on the upper terrace of the fish nest structure. 1... River, 2... Embankment, 3... Terrace revetment,
3a, 12a... Tempered glass, 4... Support structure, 10... Fish nest structure, 12... Partition wall, 14,
16...Terrace, 20, 22, 24, 26, 28
... Diffusion device, 30 ... Optical fiber, 31 ...
Light condensing device, 40...incubator, 44...promenade.

Claims (1)

[Claims] 1. A terrace revetment that extends horizontally above the water area from the revetment, and a support structure for the terrace revetment that supports the overhanging end side of the terrace revetment, is fixed to the bottom of the water area, and has a wave-dissipating function. and a fish nest structure disposed in the water area between the seawall and the support structure; and at least a diffuser pipe supported by the fish nest structure and disposed in a quiet area inside the support structure. It is characterized by having the following: an air diffuser that blows out a gas containing O ₂ ; and an optical fiber that receives natural light or light from a light source from one end and emits the light from the other end that is supported by the fish nest structure. Terrace seawall structure. 2. The terrace revetment structure according to claim 1, wherein a part of the terrace revetment is made of tempered glass. 3. The terrace revetment structure according to claim 1, wherein a promenade with a path lower than the water surface is formed on the revetment, and a part of the partition wall separating the walkway from the water area is made of tempered glass.