Methods for creating artificial tidal flats and artificial shallow areas, and artificial tidal flats or artificial shallow areas

Abstract

This will contribute to expanding the area of ​​artificial tidal flats and artificial shallow areas. [Solution] The method for creating artificial tidal flats and artificial shallow areas involves constructing a shelf section 12 by assembling multiple bamboo materials, installing the shelf section 12 near the water surface WS of the surrounding water area so that it is not washed away by the water current, and laying down a construction material 20 that serves as soil to nurture the ecosystem on top of the shelf section 12. This makes it possible to create artificial tidal flats or artificial shallow areas 10 equipped with a construction material 20 for nurturing the ecosystem not only near the shoreline but also in any water area at any depth away from the shoreline. This makes it possible to expand the area of ​​artificial tidal flats 10 and artificial shallow areas 10. Moreover, since the shelf section 12, which forms the foundation, is constructed from multiple bamboo materials, which are considered to be materials that decompose little in water and sequester carbon, it is possible to contribute to the recycling of bamboo materials and carbon dioxide sequestration.

Description

Technical Field

[0001] The present invention relates to a method for creating an artificial tidal flat or artificial shallows in a water area, and an artificial tidal flat or artificial shallows created thereby.

Background Art

[0002] Towards the realization of a carbon-neutral society, the development of offset technologies using blue carbon is necessary. For blue carbon, the amount of carbon dioxide absorption and fixation in seaweed beds such as eelgrass, seaweed beds such as kelp and wakame, or mangrove forests has been quantified and certified. In addition, in the future, evaluation and consideration of carbon dioxide absorption in tidal flats and shallows are also expected. General tidal flats and shallows exist in bays and ports across the country, and they repeatedly expose and submerge to the air part according to the ebb and flow of tides, nurturing many ecosystems. Among such ecosystems, for example, algae on tidal flats take in carbon dioxide in the atmosphere or water through photosynthesis, and seaweed and algae in shallows where sunlight reaches sufficiently also take in carbon dioxide in the water through photosynthesis.

[0003] Therefore, in tidal flats and shallows, it is expected that carbon dioxide will be reduced by the inhabiting ecosystems, and expanding the area of tidal flats and shallows is desired not only for contributing to carbon dioxide reduction towards carbon neutrality but also for creating a place for biodiversity. For this reason, in recent years, artificially creating such tidal flats and shallows has been carried out. For example, when creating an artificial tidal flat in the coastal area, the base surface of the seabed ground has been shallowed using dredged soil containing sand as a tidal flat construction material. Furthermore, there are cases where granulated materials that effectively utilize industrial by-products such as slag and fly ash are used as substitutes for sand in tidal flat construction materials (see, for example, Non-Patent Documents 1 and 2), and attempts have been made to create tidal flats in various places.

Prior Art Documents

Non-Patent Documents

[0004] [Non-Patent Document 1] "Calcia Modified Soil Research Association," [online], Calcia Modified Soil Research Association, Internet <URL: https: / / calcia.jp / > [Non-Patent Document 2] "Hi-Beads," [online], Chugoku Electric Power Co., Inc., Internet <URL: https: / / www.energia.co.jp / business / sekitanbai / pdf / hibeads.pdf> [Overview of the project] [Problems that the invention aims to solve]

[0005] However, since all of the artificial tidal flats mentioned above are located near the coastline, there are limits to how much the area of ​​the tidal flats can be expanded. This invention has been made in view of the above-mentioned problems, and its purpose is to contribute to the expansion of the area of ​​artificial tidal flats and artificial shallow areas. [Means for solving the problem]

[0006] (Modes of the invention) The following embodiments of the invention are illustrative of the configuration of the present invention and are described in separate sections to facilitate understanding of the diverse configurations of the present invention. Each section does not limit the technical scope of the present invention, and while taking into consideration the best mode for carrying out the invention, the technical scope of the present invention may also include modifications to some of the components of each section, such as substitution, deletion, or addition of other components.

[0007] (1) A method for creating an artificial tidal flat or artificial shallow area in a body of water, comprising constructing a shelf section by assembling multiple bamboo materials, installing the shelf section near the water surface of the body of water so as not to be washed away by the water current, and laying down construction material on top of the shelf section, which serves as soil to nurture the ecosystem.

[0008] The method for creating artificial tidal flats and shallow areas described in this section involves artificially creating tidal flats and shallow areas in bodies of water such as the sea or lakes. Multiple bamboo pieces are assembled to form a generally flat surface to construct a shelf that serves as the foundation for the artificial tidal flat or shallow area. The constructed shelf is then installed near the water surface of the desired body of water where the artificial tidal flat or shallow area is to be created, in a way that prevents it from being washed away by the water current. Furthermore, a construction material that acts as soil to nurture the ecosystem, similar to that found in natural tidal flats and shallow areas, is laid on top of the generally flat shelf. At this time, the shelf with the construction material already laid may also be installed in the desired body of water. This allows for the creation of artificial tidal flats or shallow areas equipped with construction material to nurture the ecosystem not only near the shoreline but also in any body of water at any depth away from the shoreline. This contributes to expanding the area of ​​artificial tidal flats and shallow areas.

[0009] In contrast, with conventional artificial tidal flats, removal requires excavation, transportation, and disposal, which destroys the established ecosystem. However, artificial tidal flats and shallow areas created using the methods described in this section can be easily removed or relocated because the entire shelf structure can be moved. Furthermore, the relocation can be carried out without causing significant damage to the established ecosystem. Moreover, the shelf structure that forms the foundation is constructed from multiple bamboo materials, which are considered to be materials that decompose little in water and sequester carbon, thus contributing to bamboo recycling and carbon dioxide sequestration.

[0010] (2) A method for creating an artificial tidal flat and an artificial shallow area, wherein, in item (1) above, multiple piles are made by bundling multiple bamboo materials together, the multiple piles are driven into the seabed of the water area at intervals from each other and penetrated, and the shelf section is installed on top of the multiple piles. The method for creating artificial tidal flats and shallow areas described in this section involves bundling multiple bamboo pieces together to create piles, and then creating multiple such piles. These multiple piles are then driven into the seabed of the desired body of water where the artificial tidal flat or shallow area will be created, spaced apart from each other. A shelf is then installed on top of the multiple driven piles, positioned near the water surface. This ensures that the shelf, where the construction material will be laid, is firmly supported by the multiple piles driven into the seabed, preventing it from being washed away by the water current. Furthermore, since each of the multiple piles is made from multiple bamboo pieces, this method contributes even more to the recycling of bamboo and the sequestration of carbon dioxide.

[0011] (3) A method for creating artificial tidal flats and artificial shallow areas, wherein the body of water is designated as a sea area in the above item (2). The artificial tidal flat and shallow area construction methods described in this section involve creating artificial tidal flats in sea areas where tides occur. Specifically, these methods utilize the tidal fluctuations of such sea areas to create an environment on the ledge where the construction materials are exposed and submerged, similar to natural tidal flats. This contributes to expanding the area of ​​artificial tidal flats and to reducing carbon dioxide emissions and creating areas for biodiversity.

[0012] (4) A method for creating an artificial tidal flat and an artificial shallow area, wherein at least a portion of the construction material on the shelf portion is repeatedly exposed and submerged in accordance with the tidal fluctuations of the sea area, and the shelf portion is fixed to the plurality of piles so that the shelf portion is located at a height below the low tide level of the sea area. The method for creating artificial tidal flats and artificial shallow areas described in this section involves fixing a shelf section to multiple piles when installing the shelf section on top of multiple piles. The height at which the shelf section is fixed is set such that at least a portion of the construction material laid on the shelf section is repeatedly exposed and submerged in accordance with the tidal fluctuations of the surrounding sea area, and the shelf section is located below the low tide level of the surrounding sea area. This creates an environment on the shelf section that resembles a natural tidal flat, and because the entire shelf section and multiple piles, which are made of bamboo, are constantly submerged, the decay of the bamboo material is suppressed.

[0013] (5) A method for creating an artificial tidal flat and an artificial shallow area, wherein the shelf portion is installed by floating it near the sea surface with the shelf portion penetrating the plurality of piles, so that the shelf portion moves in the height direction along the plurality of piles in accordance with the tidal fluctuations of the sea area. The method for creating artificial tidal flats and shallow areas described in this section involves installing a shelf section on top of multiple piles. Instead of fixing the shelf section to the piles, the shelf section is passed through the piles and installed floating near the sea surface so that the shelf section moves vertically along the piles in accordance with the tidal fluctuations of the surrounding sea area. In other words, the buoyancy of the entire shelf section keeps it floating near the sea surface, and each of the piles acts like a slide guide to guide the vertical movement of the shelf section while preventing horizontal movement due to water currents. By keeping the shelf section floating in this way, the load borne by each of the piles (supporting the shelf section load when exposed to water, pulling it out due to buoyancy when submerged, and the repeated loads) is reduced compared to when the shelf section is fixed to the piles. This reduces the design specifications required for the piles, contributing to cost reduction through the miniaturization and reduction in the number of piles.

[0014] (6) A method for creating artificial tidal flats and artificial shallow areas, wherein, as the construction material in item (4) or (5) above, the construction material is a calcia-modified soil which has been adjusted to low strength by mixing a calcia material with dredged clay soil to suppress strength development, or a calcia-modified soil in which the degree of mixing of dredged clay soil and calcia material has been adjusted to create a construction ground with uneven strength. The method for creating artificial tidal flats and artificial shallow areas described in this section uses calcia-modified soil as a construction material to be laid on the ledge. Although calcia-modified soil tends to become relatively hard, the calcia-modified soil used is either calcia-modified soil that has been adjusted to low strength, or calcia-modified soil whose mixing degree has been adjusted to create uneven strength, thereby making it soft enough for ecosystems to inhabit. In other words, for example, calcia material whose calcium leaching amount has been limited by steam curing or water curing is mixed with dredged clay soil to suppress strength development, thereby using calcia-modified soil that has been adjusted to low strength, or calcia-modified soil in which the mixing degree of dredged clay soil and calcia material is intentionally kept light to create a construction ground with uneven strength (intentionally creating low-strength areas with low improvement). This allows for the effective utilization of dredged soil that has been improved in properties as calcium-modified soil, possessing sufficient strength to prevent erosion or runoff by waves, for example, while creating a biodiversity environment.

[0015] (7) A method for creating an artificial tidal flat and an artificial shallow area, wherein the construction material is laid horizontally on the shelf portion as described in item (4) or (5) above. The method for creating artificial tidal flats and shallow areas described in this section involves laying the construction material horizontally on the ledge, thereby simultaneously exposing the entire area of ​​construction material laid on the ledge to the effects of tidal ebb and flow. This maximizes the use of the limited size of the ledge, providing a large area that functions as a tidal flat.

[0016] (8) A method for creating an artificial tidal flat and an artificial shallow area, wherein the construction material is laid on the shelf portion with a gentle slope, as described in item (4) or (5) above. The method for creating artificial tidal flats and shallow areas described in this section involves laying construction materials on the ledge with a gentle slope, thereby exposing the materials on the ledge to the effects of tidal ebb and flow over time. This creates an environment similar to a natural tidal flat with a gentle slope.

[0017] (9) In the above (4) or (5), a method for creating an artificial tidal flat and an artificial shallows, comprising providing a water-permeable dike on the outer periphery of the shelf portion, and then spreading the construction material inside the dike. The method for creating an artificial tidal flat and an artificial shallows according to this paragraph provides a water-permeable dike on the outer periphery of the shelf portion and spreads the construction material inside the dike. As a result, while the scouring of the construction material by waves is prevented by the dike, since the dike has water permeability, the influence of the ebb and flow of tides is given without problems, and the function of the tidal flat is maintained.

[0018] (10) In the above (9), a method for creating an artificial tidal flat and an artificial shallows, comprising laying a sand-proof sheet or bamboo on the inner wall of the dike and on the shelf portion before spreading the construction material. The method for creating an artificial tidal flat and an artificial shallows according to this paragraph lays a sand-proof sheet or bamboo on the inner wall of the dike and on the shelf portion before spreading the construction material, and spreads the construction material thereon. As a result, while allowing the intrusion of seawater into the inside of the shelf portion, the outflow of the construction material to the outside of the shelf portion is prevented, so that the function of the tidal flat due to the influence of the ebb and flow of tides is not impaired and the leakage of the construction material is prevented. Further, when laying bamboo, the bamboo is effectively utilized and further contributes to the fixation of carbon dioxide.

[0019] (11) In the above (10), a method for creating an artificial tidal flat and an artificial shallows, comprising installing the shelf portion in which the dike, the sand-proof sheet or bamboo, and the construction material are installed on the plurality of piles. The method for creating an artificial tidal flat and an artificial shallows according to this paragraph pre-installs a dike, a sand-proof sheet or bamboo, and a construction material on a shelf portion constructed of bamboo, and installs the shelf portion in this precast state on a plurality of piles driven into the seabed using, for example, a crane. As a result, by performing the installation work of the dike, the construction material, etc. on the shelf portion at a stable location such as on land, the construction period can be shortened and the construction accuracy can be improved compared to the case of performing the installation work at sea.

[0020] (12) In the above (4) or (5), a method for creating an artificial tidal flat and an artificial shallows by stretching a rope fixed with seaweed seedlings around the underwater part of the plurality of piles. The method for creating an artificial tidal flat and an artificial shallows described in this item is to stretch a rope fixed with seaweed seedlings such as wakame around the underwater part of a plurality of piles driven into the seabed so as not to interfere with the shelf part, for example. As a result, in addition to the fixation of carbon dioxide by the bamboo materials forming the shelf part and the piles, and the fixation of carbon dioxide in the created artificial tidal flat, the fixation of carbon dioxide by the seaweed growing in the sea is achieved, so that more carbon dioxide is fixed.

[0021] (13) In the above (5), while passing the shelf part through the plurality of piles and floating freely near the sea surface, the balance between the total weight and buoyancy of the entire shelf part is adjusted so that at least a part of the construction material on the shelf part dries out. A stopper member is installed above the penetration position of the shelf part on the plurality of piles, and the shelf part rising with the rising tide in the sea area is restricted from rising by the stopper member below the height at which it rises at high tide, and the position of the stopper member is adjusted so that the entire construction material on the shelf part is submerged at high tide and around it. A method for creating an artificial tidal flat and an artificial shallows.

[0022] The method for constructing artificial tidal flats and artificial shallow areas described in this section involves installing a shelf section by penetrating it through multiple piles and floating it near the sea surface. In this case, the balance between the weight of the entire shelf section, including the construction materials, and the buoyancy is adjusted so that at least a portion of the construction materials on the shelf section is exposed to the air when the shelf section is allowed to float freely. Even with construction materials placed on the shelf section, sufficient buoyancy is ensured by the multiple bamboo materials that make up the shelf section, making it easy to float the shelf section and adjust the balance as described above. Furthermore, stopper members are installed on the parts of the multiple piles driven into the seabed above the point where the shelf section penetrates, and the position of the stopper members is adjusted so that the following condition is met. That is, the shelf section, which rises along the multiple piles in accordance with the rising tide in the surrounding sea area, is restricted from rising below the height it rises to at high tide by the stopper members installed on the multiple piles, and the position of the stopper members is adjusted so that the entire construction material on the shelf section is submerged at high tide and around that time.

[0023] As a result, the shelf section, with its weight and buoyancy balanced as described above, floats freely without interference from the stopper member. During the period around low tide, at least a portion of the structural material on the shelf section is exposed. When its upward movement is restricted by the stopper member, the exposed portion of the structural material gradually becomes submerged as the tide rises, until the entire structural material on the shelf section is submerged during the period around high tide. Subsequently, as the tide falls, at least a portion of the structural material on the shelf section becomes exposed again, and in this state, the shelf section descends below the stopper member and floats freely once more. In this way, an environment is created that possesses the characteristics of a tidal flat, where the structural material on the shelf section is exposed and submerged while the shelf section floats near the sea surface.

[0024] (14) In item (5) above, the balance between the weight and buoyancy of the entire shelf is adjusted so that the entire structure on the shelf is submerged, while the shelf is allowed to float freely near the surface of the sea by passing through the plurality of piles, and an anti-slip member is installed in the middle of the range in which the shelf moves on the plurality of piles to temporarily restrict the passage of the shelf, so that when the shelf, which descends with the ebb tide from high tide in the area, reaches the anti-slip member from above, the descent of the shelf is stopped by the anti-slip member, and the buoyancy of the entire shelf decreases with the ebb tide. A method for creating artificial tidal flats and artificial shallow areas, wherein, as the tide rises from low tide in the sea area, the weight of the entire shelf exceeds the support force of the anti-slip member and the buoyancy of the entire shelf, causing the shelf to slide down past the anti-slip member; as the tide rises, the shelf rises to the anti-slip member from below, and the rise of the shelf is stopped by the anti-slip member; and as the buoyancy of the entire shelf increases with the rising tide, the buoyancy of the entire shelf exceeds the resistance force of the anti-slip member and the weight of the entire shelf, causing the shelf to float up past the anti-slip member.

[0025] The method for constructing artificial tidal flats and artificial shallow areas described in this section involves installing a shelf section by penetrating it through multiple piles and floating it near the sea surface. In this case, the balance between the weight of the entire shelf section, including the construction materials, and the buoyancy is adjusted so that when the shelf section is allowed to float freely in this state, the entire construction material on the shelf section is submerged. As mentioned in section (13) above, even if construction materials are placed on the shelf section, sufficient buoyancy is ensured by the multiple bamboo materials that make up the shelf section, making it easy to float the shelf section and adjust the balance as described above. Furthermore, by installing anti-slip members that temporarily restrict the passage of the shelf section in the range of movement of the shelf section penetrating the multiple piles driven into the seabed, the shelf section is made to operate as follows: That is, when the shelf section descends along the multiple piles in accordance with the ebb tide from high tide in the surrounding sea area, when it reaches the anti-slip members installed on the multiple piles from above, the shelf section becomes supported by the anti-slip members, and the descent of the shelf section is temporarily stopped by the anti-slip members. Then, as the tide continues to recede, the buoyancy of the entire shelf decreases, and the weight of the entire shelf, including the construction materials, exceeds the support force of the anti-slip members and the buoyancy of the entire shelf. As a result, the shelf quickly passes the anti-slip members and slides down along the multiple piles.

[0026] Furthermore, as the shelf rises along multiple piles in response to the rising tide from low tide in the surrounding sea area, when it reaches the anti-slip members installed on the piles from below, the movement of the shelf is hindered by the anti-slip members, and the upward movement of the shelf is temporarily stopped by the anti-slip members. Then, as the buoyancy of the entire shelf increases with the continuing rising tide, the buoyancy of the entire shelf exceeds the resistance of the anti-slip members and the weight of the entire shelf including the construction materials, causing the shelf to quickly pass the anti-slip members and float upward. As a result, the shelf, with its weight and buoyancy balanced as described above, floats freely without interference from the anti-slip members, and during the period around high tide, the entire construction material on the shelf is submerged. Then, when the shelf reaches the anti-slip members from above and is supported by the anti-slip members, the construction material on the shelf gradually becomes exposed as the tide level drops, and during this period, at least a portion of the construction material is exposed.

[0027] Subsequently, as the tide level drops further and the shelf slides past the anti-slip member, the shelf becomes free to float, and the entire structure on the shelf becomes submerged again. This state continues for the period around low tide. Then, as the tide level rises, the shelf reaches the anti-slip member from below, and its upward movement is stopped by the member. As the tide rises further, the buoyancy of the entire shelf increases, and the shelf quickly passes the anti-slip member. The tide level cannot keep up with the rise of the shelf, and the shelf is temporarily supported by the anti-slip member, leaving at least a portion of the structure exposed. Subsequently, as the tide level rises, the shelf becomes free to float, and the entire structure on the shelf becomes submerged again. In this way, an environment is created that possesses the characteristics of a tidal flat, where the shelf floats near the sea surface, while the structure on the shelf is exposed and submerged.

[0028] (15) A method for creating an artificial tidal flat and an artificial shallow area, wherein the shelf portion is moored from the bottom of the water area by a plurality of rope-like structures, as described in item (1) above. The method for creating artificial tidal flats and shallow areas described in this section involves securing the shelves near the water surface with multiple rope-like structures to prevent them from being swept away by water currents. This eliminates the need to construct piles from bamboo or other materials and drive them into the seabed, thus reducing labor and costs compared to, for example, installing shelves on piles driven into the seabed. Furthermore, since the rope-like structures can be easily connected to and removed from the shelves, installation, removal, and relocation of the shelves are also made easier. In addition, even in deep waters where the length of bamboo piles is insufficient, the shelves can be installed without problems using multiple rope-like structures extending from the seabed.

[0029] (16) A method for creating an artificial tidal flat and an artificial shallow area, wherein a plurality of the shelves described in item (2) or (15) above are installed in the water area. The method for creating artificial tidal flats and shallow areas described in this section involves installing multiple shelf-like structures, which form the foundation of the artificial tidal flats and shallow areas, in the body of water where the artificial tidal flats and shallow areas are to be created, using multiple piles or rope-like structures. This allows for the creation of artificial tidal flats and shallow areas of any size in any body of water, and the amount of recycled bamboo and carbon dioxide sequestered increases in proportion to the size of the artificial tidal flats and shallow areas.

[0030] (17) An artificial tidal flat or artificial shallow area created in a body of water, comprising a shelf section constructed by assembling a plurality of bamboo materials, a plurality of piles each formed by bundling a plurality of bamboo materials, and a construction material laid on top of the shelf section, which serves as soil for nurturing an ecosystem, wherein the plurality of piles are driven into the bottom of the body of water at intervals from each other, and the shelf section is installed on top of the plurality of piles. The artificial tidal flats or shallow areas described in this section are constructed in bodies of water such as the sea or lakes, and include a shelf, multiple piles, and construction materials. The shelf is the foundation of the artificial tidal flat or shallow area, and is constructed by assembling multiple bamboo pieces to be generally flat. Each of the multiple piles is formed by bundling multiple bamboo pieces together, and these multiple piles are driven into the seabed of any body of water where an artificial tidal flat or shallow area is to be constructed, spaced apart from each other. The construction materials serve as soil and sand to nurture the ecosystem, similar to those found in natural tidal flats and shallow areas, and are laid on top of the generally flat shelf. The shelf, on which the construction materials are laid, is then installed on top of the multiple piles driven into the seabed so that it is located near the water surface and not washed away by the water current.

[0031] This will allow for the creation of artificial tidal flats or shallow areas equipped with materials for nurturing ecosystems, not only near the shoreline but also in any body of water at any depth away from the shoreline. This will contribute to expanding the area of ​​artificial tidal flats and shallow areas. Furthermore, while the removal of typical artificial tidal flats requires excavation, transportation, and disposal, which destroys the established ecosystem, the artificial tidal flats or shallow areas described in this section can be moved as a whole. Therefore, removal and relocation can be carried out easily, and the established ecosystem can be moved without significant damage. Moreover, the shelf section and multiple piles that form the foundation are constructed from multiple types of bamboo, a material that is considered to have low corrosion in water and to sequester carbon, thus contributing to bamboo recycling and carbon dioxide sequestration.

[0032] (18) The construction material further comprises a water-permeable weir formed on the outer periphery of the shelf portion, and a sand-preventing sheet or bamboo laid on the inner wall of the weir and on the shelf portion, wherein the construction material is laid on top of the sand-preventing sheet or bamboo to create an artificial tidal flat or artificial shallow area. The artificial tidal flats or shallow areas described in this section further include a weir and a sand-preventing sheet or bamboo grass. The weir is formed around the outer perimeter of the ledge and is permeable to water, while the sand-preventing sheet or bamboo grass is laid on the inner wall of the weir and on the ledge. The construction material is then laid on top of the sand-preventing sheet or bamboo grass, on the ledge inside the weir. This prevents the construction material from being eroded by waves by the weir, and the sand-preventing sheet or bamboo grass prevents the construction material from leaking out to the outside of the ledge. Moreover, since the weir is permeable to water, and the sand-preventing sheet and bamboo grass also allow water to pass through, the construction material on the ledge is affected by the ebb and flow of tides, or the construction material is constantly submerged, depending on the environment of the installation area, thus maintaining the function of the tidal flat or shallow area without problems. Furthermore, when bamboo grass is laid, it is effectively utilized in addition to bamboo, further contributing to carbon dioxide sequestration. [Effects of the Invention]

[0033] Because the present invention has the above-described configuration, it can contribute to expanding the area of ​​artificial tidal flats and artificial shallow areas. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic perspective diagram showing an example of the structure of an artificial tidal flat according to an embodiment of the present invention, which was created by the method for creating an artificial tidal flat and an artificial shallow area according to an embodiment of the present invention. [Figure 2] This is a schematic perspective view illustrating an example of the shelf configuration. [Figure 3] This is a schematic perspective diagram showing an example of a pile configuration. [Figure 4] This is a perspective view showing a configuration in which shelves are installed on top of multiple piles. [Figure 5] This is a schematic perspective view illustrating an example of a configuration different from that shown in Figure 1 of an artificial tidal flat created by the method for creating artificial tidal flats and artificial shallow areas according to an embodiment of the present invention. [Figure 6] This is a schematic perspective view illustrating an example of a dam's structure. [Figure 7] This is a cross-sectional image illustrating the state of the construction materials laid on the shelf. [Figure 8] This is a cross-sectional diagram illustrating a method for achieving both the exposure and submersion of construction materials. [Figure 9] Following on from Figure 8, this is a cross-sectional diagram illustrating a method for achieving both the exposure and submersion of construction materials. [Figure 10] This is a cross-sectional diagram illustrating a method different from those shown in Figures 8 and 9, for achieving both the drying and submersion of construction materials. [Figure 11] Following Figure 10, this is a cross-sectional diagram illustrating a method different from those in Figures 8 and 9 for achieving both the drying and submersion of the construction materials. [Figure 12] Figures 8 to 11 show graphs illustrating the drying and submersion cycles of construction materials using the methods described. [Figure 13]Figures 10 and 11 show cross-sectional images illustrating the action of the anti-slip member used in the method. [Figure 14] This is a perspective view illustrating the process of installing a shelf section with pre-fabricated dams and construction materials. [Figure 15] This is a perspective view diagram showing how multiple artificial tidal flats or artificial shallow areas according to an embodiment of the present invention are constructed in a row behind a breakwater. [Figure 16] This is a schematic perspective view illustrating an example of a configuration different from that shown in Figures 1 and 5 of an artificial tidal flat or artificial shallow area created by the method for creating artificial tidal flats and artificial shallow areas according to an embodiment of the present invention. [Modes for carrying out the invention]

[0035] Hereinafter, embodiments for carrying out the present invention will be described based on the attached drawings. Here, detailed explanations of parts identical to or corresponding to those in the prior art will be omitted, and throughout the drawings, identical or corresponding parts are indicated by the same reference numerals. Figure 1 shows an artificial tidal flat or shallow area 10 (10A) according to an embodiment of the present invention, which is created by an artificial tidal flat or shallow area creation method according to an embodiment of the present invention, for creating artificial tidal flats or shallow areas in the sea or lakes and marshes, including freshwater lakes and brackish lakes. The artificial tidal flat or shallow area 10 becomes an artificial tidal flat or an artificial shallow area depending on the environment of the body of water in which it is installed and the depth of water in which it is installed. That is, in the sea where tides occur, if it is installed at a depth affected by such tides, it becomes an artificial tidal flat, and in lakes, marshes, or the sea where there are no tides, if it is at a relatively shallow depth and is always submerged, it becomes an artificial shallow area. The artificial tidal flat or shallow area 10A in Figure 1 is created as an artificial tidal flat 10A installed to perform the function of a tidal flat.

[0036] As shown in Figure 1, the artificial tidal flat 10A according to an embodiment of the present invention includes a shelf section 12, construction material 20, a plurality of stakes 24, a sand-preventing sheet 34, and ropes 38. The shelf section 12 is installed near the water surface WS (sea surface SS) and is constructed by assembling a plurality of bamboo materials 60 as shown in Figure 2, but is not limited to this, for example, a plurality of bamboo materials 60 are stacked in at least two layers, and the upper part is constructed in a roughly rectangular shape in plan view so that it is generally flat. When fixing the plurality of bamboo materials 60 in an assembled state, they may be fixed in any way that will not corrode or come undone even underwater, for example, by fixing them with binding material. In Figure 2, the shelf section 12 has two layers of bamboo materials 60 all assembled in the same direction, but for example, the upper bamboo materials 60 and the lower bamboo materials 60 may be assembled in directions perpendicular to each other. Furthermore, a sand-preventing sheet 34, which will be described later, is laid on the shelf section 12 in Figure 2. Depending on the length of the bamboo material 60 used, such shelf sections 12 are formed to a size of approximately 5m x 5m to 20m x 20m in plan view.

[0037] Returning to Figure 1, the construction material 20 serves as soil that nurtures the ecosystem, and any material capable of performing such a function may be used, including sandy soil, clay-mixed sand, modified calcium carbonate, or other coal ash-derived modifiers. When using modified calcium carbonate, it is preferable to adjust it to a low strength or adjust the degree of mixing so that the strength is uneven, so that it is soft enough for the ecosystem to inhabit. To adjust the modified calcium carbonate to a low strength, for example, the calcium material mixed with the dredged clay soil can be a calcium material whose calcium leaching amount has been limited by steam curing or water curing to suppress strength development. Also, when adjusting the degree of mixing, when mixing the dredged clay soil and the calcium material, intentionally mixing them lightly will result in a construction ground with uneven strength, where low-strength areas of low improvement are deliberately created. The construction material 20 is laid on top of the shelf section 12, and in this embodiment, it is laid on top of a sand-proof sheet 34 laid on top of the shelf section 12. The sand-proof sheet 34 is intended to prevent the construction material 20 from leaking out of the shelf section 12, while at the same time allowing seawater to penetrate. The specifications for such a sand-proof sheet 34 include, for example, the specifications for sand-proof sheets for ports (polyester nonwoven fabric, 4.2 mm thick or more, tensile strength of 880 N or more / 5 cm, elongation of 60% or more, mass of 500 g or more / m 2 ) Alternatively, instead of the sand-proof sheet 34, bamboo grass may be laid down to allow seawater intrusion but prevent the construction material 20 from leaking out. Furthermore, depending on the mesh size of the shelf section 12 and the particle size of the construction material 20, if there is no risk of the construction material 20 leaking out of the shelf section 12, the installation of the sand-proof sheet 34 or bamboo grass may be omitted.

[0038] Multiple piles 24 are installed to prevent the shelf section 12 from being washed away by the water current, and are driven into the seabed WB (seabed SB) of the water area (sea area) where the artificial tidal flat 10A is created, at intervals from each other. Each of the multiple piles 24 is formed by bundling together multiple bamboo materials 60, as shown in Figure 3. Each pile 24 is made up of bundles of bamboo materials 60, for example, 7 to 19 bamboo materials 60, depending on the required bearing capacity and the thickness and strength of the bamboo materials 60 used. Figure 3(a) shows an example of a pile 24 made up of 7 bundled bamboo materials 60, and Figure 3(b) shows an example of a pile 24 made up of 19 bundled bamboo materials 60. The piles 24 are bundled together with binding members 26, such as strings or strips, made of any material that does not corrode even in water.

[0039] In the embodiment shown in Figure 1, the shelf section 12 is fixed to the tops of multiple piles 24. When fixing the shelf section 12 to the multiple piles 24, any method of fixing is possible, such as fixing the tops of the multiple piles 24 to the shelf section 12 with binding material after inserting them into the shelf section 12. Since the shelf section 12 is fixed to the multiple piles 24, the shelf section 12 is supported by the multiple piles 24. For this reason, the number of multiple piles 24 used is the number necessary to support the shelf section 12, depending on local conditions such as the total weight of the shelf section 12 including the construction material 20, the bearing strength of the seabed SB ground, the water depth of the area where it is installed, and the movement due to waves. Although not limited to this, for example, in the embodiment shown in Figure 1, a total of 25 piles 24 (see Figure 4) are used in a 5x5 configuration, but some of the piles 24 are not shown in Figure 1.

[0040] The ropes 38 are stretched around the underwater portions of multiple piles 24 driven into the seabed SB, and seedlings of seaweed 42, such as wakame, are pre-attached to these ropes 38. As a result, over time, as the ropes 38 remain in place, the seaweed 42, such as wakame, grows and extends from the ropes 38, as shown in Figure 1. Here, the bamboo material 60 used for the shelf section 12 and the stakes 24 is mainly bamboo that has stopped growing and has finished fixing carbon dioxide, and any type of bamboo can be used as long as it is in such a state.

[0041] Next, the procedure for creating the artificial tidal flat 10A as shown in Figure 1 will be briefly explained. First, a shelf section 12 as shown in Figure 2 is made using multiple bamboo materials 60, and multiple piles 24 as shown in Figure 3 are also made. Then, the multiple piles 24 are driven into the seabed SB of the area where the artificial tidal flat 10A will be created to the required depth, and the shelf section 12 is fixed on top of them as shown in Figure 4. In Figure 4, the shelf section 12 is fixed in a state where it is driven into the top of the multiple piles 24, and the piles 24 and shelf section 12 are shown in a simplified manner. Furthermore, a sand-preventing sheet 34 is laid on the shelf section 12, and then construction material 20 is poured and spread on top of it. Alternatively, the shelf section 12 with the sand-preventing sheet 34 and construction material 20 laid in advance may be installed on top of the multiple piles 24. Furthermore, at any time after multiple piles 24 have been driven into the seabed SB, ropes 38 to which seaweed seedlings 42 have been pre-attached are stretched around the underwater portion of the multiple piles 24.

[0042] When constructing the artificial tidal flat 10A as described above, it is preferable that the shelf section 12 and the multiple piles 24 formed from bamboo 60 be located at a height below the low tide level of the surrounding sea area so that they are constantly submerged in the sea. In addition, the shelf section 12 is installed at a height such that at least a portion of the construction material 20 on the shelf section 12 is repeatedly exposed and submerged in accordance with the tidal fluctuations of the surrounding sea area. It is also possible to install the shelf section 12 at a height above the low tide level and below the high tide level, but in this case, there is a risk that the bamboo 60, which is sometimes above the water, will rot, so the replacement of the rotten parts or the construction of a new artificial tidal flat should be considered. Furthermore, the artificial tidal flat 10A as shown in Figure 1 is installed not on the coastline, but in a shallow sea area with a water depth of about 5 to 10 m, and in this case, it is preferable to install it in a relatively calm sea area, such as behind a breakwater 74 as shown in Figure 15, or near a quay with high calmness.

[0043] Next, Figure 5 shows the configuration of an artificial tidal flat 10B according to an embodiment of the present invention, which differs in some aspects from the artificial tidal flat 10A according to an embodiment of the present invention shown in Figure 1. Here, we will mainly explain the parts of the artificial tidal flat 10B that differ from the artificial tidal flat 10A, and will omit or simplify the explanation of parts of the artificial tidal flat 10B that are the same as or similar to the artificial tidal flat 10A. As shown in Figure 5, the artificial tidal flat 10B according to an embodiment of the present invention includes a shelf section 12, construction material 20, a plurality of piles 24, and a sand-preventing sheet 34, similar to the artificial tidal flat 10A in Figure 1. In Figure 5, for the sake of illustration, only some of the piles 24 are shown. Also, Figure 5 mainly shows the vicinity of the shelf section 12, and the underwater portions of the plurality of piles 24 are not shown, but similar to the artificial tidal flat 10A in Figure 1, ropes 38 to which seaweed seedlings 42 are fixed may be stretched around the underwater portions of the plurality of piles 24. Furthermore, the artificial tidal flat 10B includes a dam 30.

[0044] The weir 30 is designed to prevent the construction material 20 from being washed away by waves. For this reason, the weir 30 is constructed near the outer perimeter of the shelf section 12 at a height that is not affected by waves. A sand-preventing sheet 34 is laid on the inner wall of the weir 30 and on the shelf section 12 inside the weir 30, and the construction material 20 is laid on top of that. Furthermore, the weir 30 is permeable to water and is designed not to hinder the intrusion of seawater into the weir 30. In the embodiment shown in Figure 5, such a weir 30 is constructed by assembling multiple bamboo members 60, similar to the shelf section 12 and the piles 24. Any method can be used to stack and fix the multiple bamboo members 60 when constructing the weir 30. When a weir 30 constructed at the above height is formed by multiple bamboo members 60, there will be bamboo members 60 that are temporarily or permanently exposed. Such bamboo material 60 may rot, but if it does rot, the rotten part can be replaced with new bamboo material 60.

[0045] Figure 6 shows a weir 30 with a different configuration from that in Figure 5. The weir 30 in Figure 6(a) is constructed by combining relatively wide H-shaped steel beams 64, and each of the H-shaped steel beams 64 is provided with multiple holes 68 to allow water to pass through. The weir 30 in Figure 6(b) is constructed by combining relatively narrow I-shaped steel beams 66, and similar to the H-shaped steel beams 64 in Figure 6(a), each of the I-shaped steel beams 66 in Figure 6(b) is also provided with multiple holes 68. In this way, the weir 30 can be formed from any material as long as it prevents the construction material 20 inside the weir 30 from being swept away by waves and allows water to pass through.

[0046] Within the dam 30 as described above, the construction material 20 is laid out in a manner such as shown in Figure 7. In Figure 7(a), the construction material 20 is laid out on the shelf section 12 within the dam 30 so that its entirety is approximately horizontal. In contrast, in Figure 7(b), the construction material 20 is laid out on the shelf section 12 within the dam 30 with a gentle slope. The direction of the gentle slope can be arbitrarily set according to the environment of the sea area where the artificial tidal flat 10B is created, for example, so that it slopes downward towards the open sea. The degree of the gentle slope, as well as the location and number of gently sloping construction material 20 within the dam 30, can also be arbitrarily set, for example, to a height where the entire area is submerged at high tide during spring tides and exposed at low tide, and the slope is determined by the width of the shelf section 12. Now, regarding the case where calcia-modified soil is used as the construction material 20 within the dam 30, calcia-modified soil has a low permeability coefficient and is therefore impermeable to water. Consequently, the amount of water inundating from the areas covered by the calcia-modified soil within the dam 30 is small, but water inundation and drainage will mainly occur through gaps in the dam 30 located above the calcia-modified soil.

[0047] Returning to Figure 5, unlike the artificial tidal flat 10A in Figure 1, the shelf section 12 of the artificial tidal flat 10B is not fixed to the top of the multiple piles 24. Instead, the multiple piles 24 are inserted from below through multiple through holes 14 located outside the construction position of the weir 30 of the shelf section 12. In this state, the shelf section 12 is installed floating near the sea surface SS and is designed to move in the height direction along the multiple piles 24 in accordance with the tidal level fluctuations of the surrounding sea area. For this reason, the artificial tidal flat 10B in Figure 5 has fewer piles 24 than the artificial tidal flat 10A in Figure 1, in which the shelf section 12 is fixed to the multiple piles 24. However, in the embodiment of Figure 5, 16 piles 24, the same number as the number of through holes 14, are driven into the seabed SB. Furthermore, the number of bamboo materials 60 used for one pile 24 may also be less than that of the artificial tidal flat 10A in Figure 1. Furthermore, in the artificial tidal flat 10B shown in Figure 5, in order to create a tidal flat environment on the shelf 12, the shelf 12 does not simply move up and down in the same way as the tidal fluctuations of the surrounding sea area, but rather moves differently from the tidal fluctuations for certain periods. Here, we will describe two methods for realizing such movement of the shelf 12.

[0048] In the first method, as shown in Figure 5, the shelf section 12 is passed through multiple piles 24 and floats freely near the sea surface SS. The balance between the total weight of the shelf section 12 and buoyancy is adjusted so that at least a portion of the construction material 20 on the shelf section 12 is exposed. The total weight of the shelf section 12 here includes the weight of the shelf section 12, construction material 20, dam 30, and sand-preventing sheet 34. Also, as shown in Figures 8 and 9, stopper members 46 are installed on the multiple piles 24 at positions above the point where the shelf section 12 passes through, in order to limit the height to which the shelf section 12 rises. The stopper members 46 are then adjusted and fixed in the following positions. Specifically, the position of the stopper members 46 is adjusted so that when the shelf section 12 rises with the rising tide in the surrounding sea area, the rise is limited by the stopper members 46 below the height to which it rises at high tide, and the entire construction material 20 on the shelf section 12 is submerged at high tide and around that time.

[0049] The stopper member 46, fixed in the position described above, allows the shelf section 12 to operate as shown in Figures 8 and 9. Figures 8 and 9 (and Figures 10 and 11, which will be described later) focus on one of the multiple piles 24 and illustrate the operation of the shelf section 12 that penetrates that pile 24. Furthermore, each figure shows three auxiliary lines near the top, which indicate approximate tidal levels in the surrounding sea area where the artificial tidal flat 10B is installed, representing, from top to bottom, the high tide level, the mean tide level, and the low tide level. First, as shown in Figure 8(a), at low tide, the shelf section 12 is not restricted by the stopper member 46 and floats freely, so a portion of the upper side of the construction material 20 on the shelf section 12 is exposed to the air, while a portion of the lower side is submerged. The arrows (diagonal hatching) extending downward from the bottom end of shelf 12 represent the total weight of the shelf, while the arrows (diagonal hatching) extending upward from the bottom end of shelf 12 represent the buoyancy of the shelf.

[0050] In Figure 8(b), the shelf section 12 rises due to the rising tide from low tide, and during this time it floats freely without being restricted by the stopper member 46, so a part of the construction material 20 on the shelf section 12 is exposed. In Figure 8(c), the shelf section 12 has reached the stopper member 46, and the rise of the shelf section 12 is restricted by the stopper member 46, but since the tide level has not reached the upper end of the construction material 20 on the shelf section 12, a part of the construction material 20 on the shelf section 12 is still exposed. Furthermore, in Figure 8(d), although it is before high tide, the tide level has reached the upper end of the construction material 20 on the shelf section 12, so the entire construction material 20 on the shelf section 12 is submerged. In this state, the buoyancy of the shelf section 12 increases, and as indicated by the arrow near the stopper member 46, an uplift force is generated on the pile 24.

[0051] In Figure 9(a), the surrounding sea area is at high tide, and the entire structure 20 on the shelf 12, whose upward movement is restricted by the stopper member 46, is completely submerged. In Figure 9(b), the surrounding sea area is at low tide, but the tide level has still reached the upper end of the structure 20 on the shelf 12, so the entire structure 20 on the shelf 12 is submerged. In Figure 9(c), the shelf 12 is still restricted by the stopper member 46, but as the tide level drops, a part of the structure 20 on the shelf 12 begins to be exposed. In Figure 9(d), as the tide level drops further, the shelf 12 descends below the stopper member 46, and the shelf 12 floats freely without being restricted by the stopper member 46, so a part of the structure 20 on the shelf 12 is exposed. After that, it is low tide, and the situation returns to that of Figure 8(a).

[0052] Figure 12(b) shows the cycle of exposure and submersion of the construction material 20 on the shelf section 12, as described above. The timings indicated by symbols I to IV in Figure 12(b) correspond to (a) to (d) in Figure 8, and the timings indicated by symbols V to VIII correspond to (a) to (d) in Figure 9. For reference, Figure 12(a) illustrates a typical tidal flat cycle. Here, the stopper member 46 can be made of any material and formed in any shape, as long as it can restrict the rise of the shelf section 12 as described above, and the method of fixing it to the pile 24 is also arbitrary. Furthermore, the stopper member 46 does not need to be installed on all of the piles 24, but may be installed on only some of the piles 24, as long as it can restrict the rise of the shelf section 12.

[0053] Next, a second method for creating a tidal flat environment on the shelf section 12 will be described. In the second method, as shown in Figure 5, the shelf section 12 is passed through multiple piles 24 and floats freely near the sea surface SS. The balance between the weight of the entire shelf section 12 and buoyancy is adjusted so that the entire construction material 20 on the shelf section 12 is submerged. Also, as shown in Figures 10 and 11, anti-slip members 50 are installed in the middle of the range in which the shelf section 12 moves along the multiple piles 24 to temporarily restrict the passage of the shelf section 12. By installing the anti-slip members 50, the shelf section 12 is made to operate as follows.

[0054] Specifically, as shown in Figure 10(a), from high tide, the shelf section 12 descends as the tide recedes, and as shown in Figure 10(b), when the shelf section 12 reaches the anti-slip member 50 from above, the descent of the shelf section 12 is stopped by the anti-slip member 50. That is, as indicated by the arrow near the anti-slip member 50, the shelf section 12 is supported by the anti-slip member 50. Then, as shown in Figure 10(c), as the buoyancy of the entire shelf section 12 decreases with further tide receding, the weight of the entire shelf section 12 exceeds the supporting force of the anti-slip member 50 and the buoyancy of the entire shelf section 12. As a result, as shown by the arrow (grid-shaped hatching) extending downward from the shelf section 12 in Figure 10(c) and in Figure 10(d), the shelf section 12 slides down past the anti-slip member 50.

[0055] In Figures 10(a) to 10(d), the structural members 20 on the shelf section 12 are in the following states. Specifically, in Figure 10(a) at high tide, the shelf section 12 is not affected by the anti-slip member 50 and floats freely, so the entire structural member 20 on the shelf section 12 is submerged. In Figure 10(b), the descent of the shelf section 12 is stopped by the anti-slip member 50, and the tide level is below the upper end of the structural member 20 on the shelf section 12 due to the ebb tide, so a part of the upper end of the structural member 20 on the shelf section 12 is exposed. In Figure 10(c), the shelf section 12 is supported by the anti-slip member 50, and the entire structural member 20 on the shelf section 12 is exposed due to further ebb tide. Finally, in Figure 10(d), the shelf section 12 has slid down to the sea surface SS and is floating freely, so the entire structural member 20 on the shelf section 12 is submerged.

[0056] Returning to the explanation of the operation of the shelf section 12, as shown in Figure 11(a), the shelf section 12 rises from low tide as the tide rises, and as shown in Figure 11(b), when the shelf section 12 reaches the anti-slip member 50 from below, the rise of the shelf section 12 is stopped by the anti-slip member 50. In other words, the passage of the shelf section 12 is obstructed by the anti-slip member 50. Then, as shown in Figure 11(c), as the buoyancy of the entire shelf section 12 increases with further rising tide, the buoyancy of the entire shelf section 12 exceeds the resistance force of the anti-slip member 50 (see arrow near the anti-slip member 50) and the weight of the entire shelf section 12. Then, as shown by the arrow (grid-shaped hatching) extending upward from the shelf section 12 in Figure 11(c) and in Figure 11(d), the shelf section 12 passes the anti-slip member 50 and quickly floats up, and as shown by the arrow near the anti-slip member 50 in Figure 11(d), the shelf section 12 is supported by the anti-slip member 50.

[0057] In Figures 11(a) to 11(d), the structural members 20 on the shelf section 12 are in the following state. Specifically, in Figure 11(a) at low tide, the shelf section 12 floats freely without interference from the anti-slip member 50, so the entire structural member 20 on the shelf section 12 is submerged. In Figure 11(b), with the entire structural member 20 on the shelf section 12 still submerged, the shelf section 12's upward movement is stopped by the anti-slip member 50. In Figure 11(c), with the shelf section 12 stopped by the anti-slip member 50, the tide level rises further due to the rising tide, causing the entire structural member 20 on the shelf section 12 to be above the upper end of the structural member 20, so the entire structural member 20 on the shelf section 12 is completely submerged. In Figure 11(d), the shelf section 12 quickly passes over the anti-slip member 50 and becomes supported by the anti-slip member 50, so that the shelf section 12 is positioned above the state in which it is freely floating on the sea surface SS, and a portion of the construction material 20 on the shelf section 12 is exposed. In the second method, Figure 12(c) shows the cycle in which the construction material 20 on the shelf section 12 is exposed and submerged as described above. In Figure 12(c), the timings indicated by symbols I to IV correspond to (a) to (d) in Figure 10, and the timings indicated by symbols V to VIII correspond to (a) to (d) in Figure 11.

[0058] The anti-slip member 50 used in the second method may be made of any material and formed in any shape, as long as it can temporarily restrict passage over the shelf section 12 as described above. Examples of such anti-slip members 50 include those made of shape-memory stainless steel, rubber, or bamboo 60 that deform when a certain load is applied, or those that rotate when a certain load is applied, such as ratchet structures or geared gears. The anti-slip member 50 can also be fixed to the stake 24 by inserting it into the stake 24 made of bamboo 60, wrapping it around the stake 24, or screwing it to the stake 24. It should be noted that the anti-slip member 50 does not need to be installed on all of the stakes 24, but may be installed on only some of the stakes 24, as long as it can temporarily restrict passage over the shelf section 12.

[0059] Figure 13 shows a series of images illustrating how the anti-slip member 50, which deforms when a certain load is applied, temporarily restricts passage over the shelf 12. The images, from left to right, show how passage over the shelf 12 is restricted from top to bottom, and the images, from right to left, show how passage over the shelf 12 is restricted from bottom to top. In either case, as indicated by the black or white arrows, it can be seen that when the load on the anti-slip member 50 exceeds a certain value, the anti-slip member 50 deforms rapidly, allowing passage over the shelf 12 quickly. Thus, it is preferable for the anti-slip member 50 to allow passage over the shelf 12 quickly once a certain load is exceeded.

[0060] Next, the procedure for creating the artificial tidal flat 10B as shown in Figure 5 will be briefly explained. First, a shelf section 12 and a pile section 24 are constructed using multiple bamboo materials 60. Furthermore, a dam 30 is constructed on the constructed shelf section 12 as shown in Figures 5 and 6, and multiple through holes 14 are made in the part of the shelf section 12 that is outside the dam 30. Then, the pile section 24 is driven into the seabed SB of the sea area where the artificial tidal flat 10B is to be created to the required depth, and the shelf section 12 is installed on top of it so that the pile section 24 passes through the through holes 14. Furthermore, a sand-preventing sheet 34 (or bamboo grass) is laid on the inner wall of the dam 30 and on the shelf section 12 inside the dam 30, and then construction material 20 is poured and spread on top of it as shown in Figure 7. Alternatively, the shelf section 12 with the sand-preventing sheet 34 laid and the construction material 20 spread on top may be installed on top of the pile section 24. In this case, and in other cases when installing the shelf section 12 on multiple piles 24, the shelf section 12 can be suspended and installed by a crane 70 mounted on a workboat or the like, as shown in Figure 14. Additionally, stopper members 46 and anti-slip members 50, as shown in Figures 8 to 11, can be installed at appropriate positions on the multiple piles 24 as needed.

[0061] Here, although not limited thereto, we will describe more specific design details of the artificial tidal flat (artificial shallow area) 10 according to an embodiment of the present invention. When designing the artificial tidal flat 10, it is necessary to consider the buoyancy of the bamboo material 60. The basic concept is that the piles 24 formed from the bamboo material 60 can be driven into the seabed WB (seabed SB) in a self-supporting state. If the piles 24 are in a state where they will be pulled out due to the ground bearing capacity (adhesion force), steel materials or the like may be placed on the ground of the seabed WB (seabed SB), and the piles 24 may be fixedly connected to them as a buoyancy countermeasure. The buoyancy of the shelf section 12 and the weir 30 can be balanced by the weight of the construction material 20. Depending on whether the connection between the piles 24 and the shelf section 12 is fixed, as in artificial tidal flat 10A, or whether the shelf section 12 can be freely raised and lowered, as in artificial tidal flat 10B, the number of bundles of bamboo 60 on the piles 24, the resulting bearing capacity (adhesion force), and buoyancy countermeasures will be examined. Furthermore, the structural resistance to external forces, mainly horizontal, caused by waves, will need to be examined taking into account the flexibility and rigidity of the piles 24 formed from bamboo 60.

[0062] It should be noted that the method for creating artificial tidal flats and artificial shallow areas according to embodiments of the present invention, and the artificial tidal flat (or artificial shallow area) 10 created thereby, are not limited to the configurations shown in Figures 1 to 14, and various configurations can be adopted depending on the environment and conditions of the water body in which they are installed. For example, a weir 30 may be formed on the artificial tidal flat 10A in Figure 1, and the artificial shallow area 10 may be created by installing it in the sea or a lake or marsh so that the construction material 20 on the shelf section 12 shown in Figures 1 and 5 is always submerged. In this case, a part of the construction material 20 may always be exposed. Furthermore, the method for submerging and exposing the construction material 20 on the shelf section 12 of the artificial tidal flat 10B may be any method other than the method described in Figures 8 to 13. Furthermore, any number of artificial tidal flats (or artificial shallow areas) 10 may be created. For example, Figure 15 shows eight artificial tidal flats 10 created on the back of a breakwater 74. Moreover, the shelves 12 are not limited to being installed on multiple piles 24, as long as they are installed in a way that prevents them from being washed away by the water current. For example, they may be installed as shown in Figure 16. In Figure 16, the artificial tidal flat (artificial shallow area) 10C is installed in a manner in which the shelves 12 are moored by multiple rope-like bodies 54 extending from weights or anchors installed on the seabed WB (seabed SB).

[0063] Now, according to the embodiment of the present invention having the above configuration, the following effects can be obtained. That is, the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention is for artificially creating tidal flats and shallow areas in bodies of water such as the sea or lakes. As shown in Figure 2, a shelf section 12 that will serve as the foundation for the artificial tidal flat 10 or artificial shallow area 10 is constructed by assembling a plurality of bamboo materials 60 so that they are generally flat. Then, as shown in Figures 1 and 16, the constructed shelf section 12 is installed near the water surface WS of any body of water where the artificial tidal flat 10 or artificial shallow area 10 is to be created, so as not to be washed away by the water current. Furthermore, construction material 20 that serves as soil for nurturing ecosystems, similar to that found in natural tidal flats and shallow areas, is laid on top of the generally flat shelf section 12. At this time, the shelf section 12 with the construction material 20 already laid may be installed in any body of water. This makes it possible to create artificial tidal flats or artificial shallow areas 10 equipped with ecological formation materials 20 not only near the shoreline, but also in any body of water at any depth away from the shoreline. Therefore, it is possible to contribute to expanding the area of ​​artificial tidal flats 10 and artificial shallow areas 10.

[0064] In contrast, with conventional artificial tidal flats, removal requires excavation, transportation, and disposal, which destroys the established ecosystem. However, the artificial tidal flats 10 and artificial shallow areas 10 created by the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention can be moved as a whole, including the shelf section 12. This allows for easy removal and relocation, and furthermore, relocation can be carried out without significantly damaging the established ecosystem. Moreover, the shelf section 12, which forms the foundation, is constructed from multiple bamboo materials 60, a material that is known to decompose little in water and to sequester carbon. Therefore, it is possible to contribute to the recycling of the bamboo materials 60 and carbon dioxide sequestration. Although it varies depending on the type of bamboo used, the amount of carbon sequestrated per bamboo material 60 approximately 15m long is estimated to be around 10-15kg.

[0065] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to an embodiment of the present invention, as shown in Figure 3, a pile 24 is made by bundling multiple bamboo materials 60 together, and multiple such piles 24 are made. Then, as shown in Figures 1 and 5, the multiple piles 24 are driven into the seabed WB of any body of water where the artificial tidal flat 10 or artificial shallow area 10 is to be created, spaced apart from each other, and a shelf section 12 is installed on top of the multiple driven piles 24 so as to be located near the water surface WS. In this way, the shelf section 12 on which the construction material 20 is laid can be firmly supported by the multiple piles 24 driven into the seabed WB so as not to be washed away by the water flow. Moreover, since each of the multiple piles 24 is made up of multiple bamboo materials 60, it is possible to further contribute to the recycling of bamboo materials 60 and carbon dioxide sequestration.

[0066] Furthermore, the method for creating artificial tidal flats and artificial shallow areas according to embodiments of the present invention, as shown in Figures 1 and 5, involves creating an artificial tidal flat 10 in a sea area where tides occur. That is, by utilizing the tidal fluctuations of such a sea area, an environment is created on the shelf section 12 in which the construction material 20 is exposed and submerged, just like a natural tidal flat. This contributes to expanding the area of ​​the artificial tidal flat 10, and makes it possible to contribute to the reduction of carbon dioxide and the creation of a biodiversity space.

[0067] Furthermore, as shown in Figure 1, the method for creating artificial tidal flats and artificial shallow areas according to an embodiment of the present invention involves stretching ropes 38 to which seedlings of seaweed 42, such as wakame, are fixed, around the underwater portions of multiple piles 24 driven into the seabed SB, for example, so as not to interfere with the shelf sections 12. This makes it possible to fix carbon dioxide by seaweed 42 growing in the sea, in addition to the carbon dioxide fixation by the bamboo 60 forming the shelf sections 12 and piles 24, and the carbon dioxide fixation in the created artificial tidal flat 10, thereby enabling the fixation of even more carbon dioxide.

[0068] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to an embodiment of the present invention, as shown in Figure 1, when installing a shelf section 12 on top of a plurality of piles 24, the shelf section 12 is fixed to the plurality of piles 24. At this time, the height to which the shelf section 12 is fixed is set such that at least a portion of the construction material 20 laid on the shelf section 12 is repeatedly exposed and submerged in accordance with the tidal fluctuations of the surrounding sea area, and the shelf section 12 is located below the low tide level of the surrounding sea area. This makes it possible to create an environment on the shelf section 12 that resembles a natural tidal flat, and also makes it possible to keep the entire shelf section 12 and the plurality of piles 24, which are made of bamboo material 60, constantly submerged, thereby suppressing the decay of the bamboo material 60.

[0069] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, when installing the shelf section 12 on top of a plurality of piles 24, instead of fixing the shelf section 12 to the plurality of piles 24, as shown in Figure 5, the shelf section 12 may be passed through the plurality of piles 24 and installed floating near the sea surface SS so that the shelf section 12 moves in the height direction along the plurality of piles 24 in accordance with the tidal level fluctuations of the surrounding sea area. In other words, the shelf section 12 is made to float near the sea surface SS by the buoyancy of the entire shelf section 12, and each of the plurality of piles 24 acts as a slide guide to guide the height direction fluctuation of the shelf section 12 and prevent horizontal movement due to water flow. In this way, by floating the shelf section 12, the load borne by each of the multiple piles 24 can be reduced compared to the case where the shelf section 12 is fixed to multiple piles 24 (supporting the load of the shelf section when exposed to water, being pulled out by buoyancy when submerged, and the repeated loads thereon). As a result, the design specifications required for the multiple piles 24 can be reduced, which can contribute to cost reduction by making the piles 24 smaller and reducing the number of piles.

[0070] In addition, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, calcia-modified soil may be used as the construction material 20 laid on the shelf section 12. Although calcia-modified soil tends to become relatively hard, the calcia-modified soil used is either calcia-modified soil adjusted to low strength, or calcia-modified soil whose mixing degree has been adjusted to result in uneven strength, thereby making it soft enough for ecosystems to inhabit. That is, for example, calcia material whose calcium leaching amount has been limited by steam curing or water curing is mixed with dredged clay soil to suppress strength development, thereby using calcia-modified soil adjusted to low strength, or calcia-modified soil in which the mixing degree of dredged clay soil and calcia material is intentionally kept light to create a construction ground with uneven strength (intentionally creating low-strength areas with low improvement). This makes it possible to effectively utilize dredged soil that has been improved in properties as calcium-modified soil, while creating a biodiversity environment and possessing sufficient strength to prevent erosion or runoff by waves, for example. Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, when laying the construction material 20 on the shelf section 12, as shown in Figure 7(a), the construction material 20 is laid horizontally, thereby simultaneously applying the effects of tidal ebb and flow to the entire construction material 20 laid on the shelf section 12. This makes it possible to maximize the use of the shelf section 12, which has a limited size, and provide a large area that functions as a tidal flat.

[0071] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, if the construction material 20 is laid on the shelf section 12 with a gentle slope, as shown in Figure 7(b), the ebb and flow of tides can be applied to the construction material 20 on the shelf section 12 with a time difference. This makes it possible to create an environment similar to a natural tidal flat with a gentle slope. Furthermore, the method for creating artificial tidal flats and artificial shallow areas according to embodiments of the present invention, as shown in Figures 5 to 7, involves providing a water-permeable weir 30 on the outer perimeter of the shelf section 12 and laying construction material 20 inside the weir 30. This prevents erosion of the construction material 20 by waves with the weir 30, while the weir 30 is water-permeable, allowing the effects of tides to be applied without problems, thereby maintaining the function of the tidal flat.

[0072] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to embodiments of the present invention, as shown in Figures 5 and 7, a sand-preventing sheet 34 or bamboo grass is laid on the inner wall of the dam 30 and on the shelf section 12 before laying the construction material 20, and then the construction material 20 is laid on top of that. This allows seawater to penetrate into the inside of the shelf section 12 while preventing the construction material 20 from flowing out to the outside of the shelf section 12, thus preventing leakage of the construction material 20 without impairing the function of the tidal flat due to the ebb and flow of the tides. Moreover, when bamboo grass is laid, it can be effectively utilized and contribute even more to carbon dioxide sequestration.

[0073] In addition, the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention involves pre-installing a dam 30, a sand-preventing sheet 34 or bamboo grass, and construction materials 20 on a shelf section 12 constructed from bamboo 60, and then installing the precast shelf section 12 on multiple piles 24 driven into the seabed SB using a crane 70 or the like, as shown in Figure 14. This allows for shorter construction periods and improved construction accuracy compared to performing installation work at sea, by carrying out the installation of the dam 30 and construction materials 20 on the shelf section 12 in a stable location such as on land.

[0074] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, when the shelf section 12 is installed by passing it through a plurality of piles 24 and floating it near the sea surface SS as shown in Figure 5, the balance between the weight of the entire shelf section 12, including the construction material 20, and the buoyancy is adjusted so that when the shelf section 12 is allowed to float freely in such a state, at least a portion of the construction material 20 on the shelf section 12 is exposed to the air. Also, as shown in Figures 8 and 9, stopper members 46 are installed on the portion of the plurality of piles 24 driven into the seabed SB above the position through which the shelf section 12 passes, and the position of the stopper members 46 is adjusted so that the following state is achieved. That is, the shelf section 12 that rises along the plurality of piles 24 in accordance with the rising tide in the surrounding sea area is restricted from rising below the height it rises to at high tide by the stopper members 46 installed on the plurality of piles 24, and the position of the stopper members 46 is adjusted so that the entire construction material 20 on the shelf section 12 is submerged at high tide and around that time.

[0075] As a result, the shelf section 12, with its weight and buoyancy balanced as described above, floats freely without interference from the stopper member 46 during the period around low tide (see Figures 9(d), 8(a), and 8(b)), with at least a portion of the structural material 20 on the shelf section 12 exposed. When its upward movement is restricted by the stopper member 46 (see Figure 8(c)), the exposed portion of the structural material 20 gradually becomes submerged as the tide rises, and during the period around high tide (see Figures 8(d), 9(a), and 9(b)), the entire structural material 20 on the shelf section 12 becomes submerged. Subsequently, as the tide drops (see Figure 9(c)), at least a portion of the structural material 20 on the shelf section 12 becomes exposed again, and in that state, the shelf section 12 descends below the stopper member 46 and floats freely again (see Figure 9(d)). In this way, it becomes possible to create an environment that possesses the characteristics of a tidal flat, where the shelf section 12 floats near the sea surface SS, while the construction material 20 on the shelf section 12 is exposed to and submerged by the water (see Figure 12(b)).

[0076] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, when the shelf section 12 is installed by passing it through a plurality of piles 24 and floating it near the sea surface SS as shown in Figure 5, the balance between the weight of the entire shelf section 12, including the construction material 20, and the buoyancy may be adjusted so that when the shelf section 12 is allowed to float freely in such a state, the entire construction material 20 on the shelf section 12 is submerged. Then, as shown in Figures 10 and 11, by installing anti-slip members 50 that temporarily restrict the passage of the shelf section 12 in the middle of the range in which the shelf section 12 that passes through the plurality of piles 24 driven into the seabed SB operates as follows.

[0077] In other words, as the shelf section 12 descends along the multiple piles 24 in accordance with the ebb tide from high tide in the surrounding sea area, as shown in Figure 10(b), when it reaches the anti-slip members 50 installed on the multiple piles 24 from above, the shelf section 12 becomes supported by the anti-slip members 50, and the descent of the shelf section 12 is temporarily stopped by the anti-slip members 50. Then, as the buoyancy of the entire shelf section 12 decreases with the continued ebb tide, the weight of the entire shelf section 12, including the construction material 20, exceeds the support force of the anti-slip members 50 and the buoyancy of the entire shelf section 12, and as shown in Figure 10(d), the shelf section 12 quickly passes the anti-slip members 50 and slides down along the multiple piles 24.

[0078] Furthermore, as the shelf section 12 rises along the multiple piles 24 in accordance with the rising tide from low tide in the surrounding sea area, as shown in Figure 11(b), when it reaches the anti-slip members 50 installed on the multiple piles 24 from below, the movement of the shelf section 12 is hindered by the anti-slip members 50, and the upward movement of the shelf section 12 is temporarily stopped by the anti-slip members 50. Then, as the buoyancy of the entire shelf section 12 increases with the continuing rising tide, the buoyancy of the entire shelf section 12 exceeds the resistance force of the anti-slip members 50 and the weight of the entire shelf section 12 including the construction material 20, and as shown in Figure 11(d), the shelf section 12 quickly passes the anti-slip members 50 and floats to the surface.

[0079] As a result, the shelf section 12, with its weight and buoyancy balanced as described above, floats freely without interference from the anti-slip member 50. During the period around high tide (see Figure 10(a)), the entire structure material 20 on the shelf section 12 is submerged. When the shelf section 12 reaches the anti-slip member 50 from above and is supported by the anti-slip member 50 (see Figures 10(b) and 10(c)), the structure material 20 on the shelf section 12 gradually becomes exposed as the tide level drops, and during this period, at least a portion of the structure material 20 is exposed. Subsequently, as the tide level drops further and the shelf section 12 slides past the anti-slip member 50 (see Figure 10(d)), the shelf section 12 floats freely again, and the entire structure material 20 on the shelf section 12 becomes submerged once more. This state continues during the period around low tide (see Figure 11(a)).

[0080] Then, as the tide rises, the shelf section 12 reaches the anti-slip member 50 from below and its upward movement is stopped by the anti-slip member 50 (see Figure 11(b)). As the tide rises further, the buoyancy of the entire shelf section 12 increases (see Figure 11(c)), and the shelf section 12 quickly passes over the anti-slip member 50 (see Figure 11(d)). The tide level cannot keep up with the rise of the shelf section 12, and the shelf section 12 is temporarily supported by the anti-slip member 50, resulting in at least a portion of the construction material 20 being exposed. Subsequently, as the tide rises further, the shelf section 12 becomes free to float, and the entire construction material 20 on the shelf section 12 is submerged again (see Figure 10(a)). This method also makes it possible to create an environment with the characteristics of a tidal flat, where the shelf section 12 floats near the sea surface SS, while the construction material 20 on the shelf section 12 is exposed and submerged (see Figure 12(c)).

[0081] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, when installing the shelf section 12 near the water surface WS so that it is not carried away by the water current, the shelf section 12 may be moored from the seabed WB by a plurality of rope-like bodies 54, as shown in Figure 16. This eliminates the need to manufacture the piles 24 from bamboo 60 or the like, and to drive the manufactured piles 24 into the seabed WB, compared to, for example, installing the shelf section 12 on piles 24 driven into the seabed WB, thereby reducing labor and costs. Moreover, since the rope-like bodies 54 can be easily connected to and removed from the shelf section 12, the installation, removal, and relocation of the shelf section 12 can also be easily carried out. In addition, even in water areas with deep water depths where the length of bamboo 60 used as piles 24 cannot reach, the shelf section 12 can be installed without problems by a plurality of rope-like bodies 54 extending from the seabed WB.

[0082] Furthermore, in the method for creating artificial tidal flats and artificial shallow areas according to the embodiment of the present invention, the shelf sections 12 that form the foundation of the artificial tidal flats 10 and artificial shallow areas 10 may be installed in multiple locations in the body of water where the artificial tidal flats 10 and artificial shallow areas 10 are to be created, for example, as shown in Figure 15, using multiple piles 24 and multiple rope-like bodies 54. This makes it possible to create artificial tidal flats 10 and artificial shallow areas 10 of any size in any body of water, and thus the amount of recycled bamboo 60 and the amount of carbon dioxide sequestrated can be increased according to the size of the artificial tidal flats 10 and artificial shallow areas 10.

[0083] On the other hand, the artificial tidal flat or artificial shallow area 10 according to the embodiment of the present invention is constructed in a body of water such as the sea or a lake, and as shown in Figures 1 and 5, it includes a shelf section 12, a plurality of piles 24, and construction material 20. The shelf section 12 is the foundation part of the artificial tidal flat or artificial shallow area 10, and as shown in Figure 2, it is constructed by assembling a plurality of bamboo materials 60 so that they are generally flat. Each of the plurality of piles 24 is formed by bundling a plurality of bamboo materials 60, as shown in Figure 3, and the plurality of piles 24 thus formed are driven into the seabed WB of any body of water where the artificial tidal flat or artificial shallow area 10 is to be constructed, with intervals between them. The construction material 20 plays the role of soil that nurtures ecosystems, similar to the soil found in natural tidal flats and shallow areas, and is laid on top of the generally flat shelf section 12. Then, the shelf section 12 on which the construction material 20 is laid is installed on top of multiple piles 24 driven into the seabed WB so that it is located near the water surface WS and is not washed away by the water current.

[0084] This makes it possible to create artificial tidal flats or artificial shallow areas 10 equipped with ecological formation materials 20 not only near the shoreline but also in any body of water at any depth away from the shoreline. This contributes to expanding the area of ​​artificial tidal flats 10 and artificial shallow areas 10. Furthermore, while conventional artificial tidal flats require excavation, transportation, and disposal during removal, resulting in the destruction of established ecosystems, the artificial tidal flats or artificial shallow areas 10 according to the embodiment of the present invention can be moved as a whole, including the shelf section 12. Therefore, removal and relocation can be easily carried out, and furthermore, relocation can be done without causing significant damage to the established ecosystem. Moreover, since the shelf section 12 and the multiple piles 24 that form the foundation are constructed from multiple bamboo materials 60, which are materials that are evaluated as having little corrosion in water and sequestering carbon, it is possible to contribute to the recycling of bamboo materials 60 and carbon dioxide sequestration.

[0085] Furthermore, as shown in Figure 5, the artificial tidal flat or artificial shallow area 10 according to the embodiment of the present invention further includes a weir 30 and a sand-preventing sheet 34 or bamboo grass. The weir 30 is formed on the outer periphery of the shelf section 12 and is permeable to water. The sand-preventing sheet 34 or bamboo grass is laid on the inner wall of the weir 30 and on the shelf section 12. The construction material 20 is then laid on the shelf section 12 inside the weir 30, on top of the sand-preventing sheet 34 or bamboo grass. This prevents the construction material 20 from being eroded by waves by the weir 30, and the sand-preventing sheet 34 or bamboo grass also prevents the construction material 20 from leaking out to the outside of the shelf section 12.

[0086] Moreover, since the weir 30 is permeable to water, and the sand-preventing sheet 34 and bamboo also allow water to pass through, it is possible to maintain the function of the tidal flat or shallow area without problems by influencing the reclaimed material 20 on the shelf section 12 with the ebb and flow of the tides, or by keeping the reclaimed material 20 constantly submerged, depending on the environment of the water area where it is installed. Furthermore, if bamboo is laid, the bamboo can be effectively utilized in addition to the bamboo material 60, further contributing to carbon dioxide sequestration. It should be noted that if the weir 30 is constructed of bamboo material 60 in addition to the shelf section 12 and multiple piles 24, there are estimates that the amount of carbon sequestrated per artificial tidal flat or shallow area 10 (in the case of approximately 15m x 15m) will be 50 tons or more, depending on the size of the artificial tidal flat or shallow area 10. [Explanation of Symbols]

[0087] 10 (10A, 10B, 10C): Artificial tidal flat (artificial shallow area), 12: Shelf section, 20: Construction material, 24: Stake, 30: Dam, 34: Sand control sheet, 38: Rope, 42: Seaweed, 46: Stopper member, 50: Anti-slip member, 54: Cord-like body, 60: Bamboo material, WS: Water surface, WB: Seabed, SS: Sea surface, SB: Seabed

Claims

1. A method for creating artificial tidal flats or artificial shallow areas in a body of water, Multiple bamboo pieces were assembled to construct the shelf section. The shelf section is installed near the water surface of the aforementioned body of water so as not to be washed away by the water current. A method for creating artificial tidal flats and artificial shallow areas, characterized by laying down construction material that serves as soil for nurturing ecosystems on top of the aforementioned shelf sections.

2. Multiple stakes were made by bundling several pieces of bamboo together. The aforementioned multiple piles are driven into the seabed of the body of water at intervals from each other and penetrated into the water. The method for creating an artificial tidal flat and an artificial shallow area according to claim 1, characterized in that the shelf portion is installed on top of the plurality of piles.

3. The method for creating an artificial tidal flat and an artificial shallow area according to claim 2, characterized in that the aforementioned body of water is set as a sea area and an artificial tidal flat is created.

4. The method for creating an artificial tidal flat and an artificial shallow area according to claim 3, characterized in that at least a portion of the construction material on the shelf is repeatedly exposed and submerged in accordance with the tidal fluctuations of the sea area, and the shelf is fixed to the plurality of piles so that the shelf is located at a height below the low tide level of the sea area.

5. The method for creating an artificial tidal flat and an artificial shallow area according to claim 3, characterized in that the shelf portion is installed floating near the sea surface with the shelf portion penetrating the plurality of piles, such that the shelf portion moves in the height direction along the plurality of piles in accordance with the tidal fluctuations in the aforementioned sea area.

6. The method for creating artificial tidal flats and artificial shallow areas according to claim 4 or 5, characterized in that the aforementioned construction material is a calcia-modified soil in which the amount of calcium leaching is limited and the strength development is suppressed by mixing it with dredged clay soil to suppress strength development, or a calcia-modified soil in which the degree of mixing of dredged clay soil and calcia material is adjusted to create a construction ground with uneven strength.

7. The method for creating an artificial tidal flat and an artificial shallow area according to claim 4 or 5, characterized in that the construction material is laid horizontally on the shelf portion.

8. The method for creating an artificial tidal flat and an artificial shallow area according to claim 4 or 5, characterized in that the aforementioned construction material is laid on the shelf portion with a gentle slope.

9. A method for creating an artificial tidal flat and an artificial shallow area according to claim 4 or 5, characterized in that a water-permeable weir is provided on the outer periphery of the shelf section, and then the construction material is laid inside the weir.

10. The method for creating an artificial tidal flat and an artificial shallow area according to claim 9, characterized in that, before laying the aforementioned construction material, a sand-preventing sheet or bamboo grass is laid on the inner wall of the dam and on the shelf portion.

11. The method for creating an artificial tidal flat and an artificial shallow area according to claim 10, characterized in that the shelf section, in which the dam, the sand-preventing sheet or bamboo grass, and the construction material are installed, is installed on the plurality of piles.

12. The method for creating an artificial tidal flat and artificial shallow area according to claim 4 or 5, characterized in that ropes to which seaweed seedlings are attached are stretched around the underwater portion of the plurality of piles.

13. With the aforementioned shelf section penetrated by the plurality of piles and floating freely near the sea surface, the balance between the overall weight and buoyancy of the shelf section is adjusted so that at least a portion of the construction material on the shelf section is exposed to the air. A stopper member is installed above the point where the plurality of piles penetrate the shelf section. The method for creating an artificial tidal flat and an artificial shallow area according to claim 5, characterized in that the position of the stopper member is adjusted so that the shelf portion, which rises with the rising tide in the aforementioned sea area, is limited to rising below the height it rises to at high tide, and the entire structure of the construction material on the shelf portion is submerged at high tide and around that time.

14. With the aforementioned shelf section penetrated by the plurality of piles and floating freely near the sea surface, the balance between the weight and buoyancy of the entire shelf section is adjusted so that the entire structure on the shelf section is submerged. By installing anti-slip members that temporarily restrict passage through the shelf portion in the middle of the range in which the shelf portion of the plurality of piles moves, As the tide descends from high tide in the aforementioned sea area, the shelf section, which is descending with the ebb tide, reaches the anti-slip member from above, and the descent of the shelf section is stopped by the anti-slip member. As the buoyancy of the entire shelf section decreases with the ebb tide, the weight of the entire shelf section exceeds the supporting force of the anti-slip member and the buoyancy of the entire shelf section, causing the shelf section to slide down past the anti-slip member. The method for creating an artificial tidal flat and an artificial shallow area according to claim 5, characterized in that when the shelf portion, which rises with the rising tide from low tide in the aforementioned sea area, reaches the anti-slip member from below, the rise of the shelf portion is stopped by the anti-slip member, and as the buoyancy of the entire shelf portion increases with the rising tide, the buoyancy of the entire shelf portion exceeds the resistance force of the anti-slip member and the weight of the entire shelf portion, causing the shelf portion to pass the anti-slip member and float up.

15. The method for creating an artificial tidal flat and an artificial shallow area according to claim 1, characterized in that the shelf portion is moored from the bottom of the water body by a plurality of rope-like structures.

16. The method for creating an artificial tidal flat and an artificial shallow area according to claim 2 or 15, characterized in that a plurality of the aforementioned shelf sections are installed in the water area.

17. An artificial tidal flat or artificial shallow area created in a body of water, The shelf section is constructed by assembling multiple pieces of bamboo, Multiple stakes formed by bundling multiple pieces of bamboo together, The above-mentioned shelf section is covered with construction material that serves as soil and sand to nurture the ecosystem, and includes the following: The aforementioned plurality of piles are driven into the bottom of the body of water at intervals from each other. The aforementioned shelf section is characterized by being installed on top of the plurality of piles, making it an artificial tidal flat or artificial shallow area.

18. A water-permeable weir formed on the outer periphery of the aforementioned shelf section, The invention further includes a sand-preventing sheet or bamboo laid on the inner wall of the dam and on the shelf portion, The artificial tidal flat or artificial shallow area according to claim 17, characterized in that the construction material is laid on top of the sand-preventing sheet or the bamboo grass.

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