JP2007231543A - Creation method for artificial tideland, and artificial tideland - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a creation method for an artificial tideland which is equipped with the function of persistently maintaining a food chain intrinsic in the nature, and also to provide the artificial tideland. <P>SOLUTION: Tideland deposit soil 10, the color of which has the high absorptivity of the solar radiation in wet conditions, is borrowed in an intertidal area on coastal soil 6 which is gently inclined over the vertical direction of the intertidal area. The temperature of coastal seawater 1 is increased by repeating the absorption of the solar radiation by the deposit soil 10 at low tide and the transfer of heat to the seawater 1 from the deposit soil 10 at high tide. Preferably, the lightness of the tideland deposit soil 10 in the wet condition is brought nearer to black than to white, and the color of the deposit soil 10 is adjusted by mixing a carbon granule, a dye-mixed concrete granule and/or sulfide-mixed dredged soil together. More preferably, the coastal soil 6 is enclosed with a wave-dissipating wall 4 with an opening, and the temperature of the seawater 1 in the wave-dissipating wall 4 is increased while ocean waves toward the costal soil 6 from the outside of the wave-dissipating wall 4 are suppressed. Desirably, the area of a sea surface inside the wave-dissipating wall 4 at low tide is set at 40% or less of the area of the sea surface at high tide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for creating an artificial tidal flat and an artificial tidal flat, and more particularly to a method for creating an artificial tidal flat and various artificial tidal flats in which various organisms can live continuously.

  It is a problem that the habitat of living organisms in the coastal area is destroyed and the biological resources are significantly weakened by constructing the coastal area, the coastal area and the surrounding land area with artificial structures such as concrete. It has become. Recently, in order to regenerate rich coasts and coastal areas where organisms inhabit, conservation and regeneration of artificial tidal flats and seaweed beds have been actively promoted. In particular, the tidal flat is a habitat for various organisms where water, land, and air come into contact with each other. It is also important as a place with functions such as water purification, mitigation of climate change, and migratory bird resting and feeding areas.

  An example of a conventional method for the maintenance and regeneration of artificial tidal flats is to put earth and sand such as mountain sand and channel dredging into the sea and land, and then spread artificial sand on top of it using a spreader. It is. Further, Patent Document 1 puts any one of sand, fine particles, lightweight materials, organic matter, humus, fertilizer, bacteria, juveniles, and seeds into a plurality of raw material tanks, and these can be used for living ground. A method and apparatus for producing tideland-covered sand, which is blended by a mixing device so as to provide sand that can provide the optimum bottom sediment for the living conditions of the desired organism to be cultivated in accordance with the height and planar arrangement, and is sprayed to the tidal flat formation sea area by a spraying device. Has proposed.

JP 2000-314116 A Yumi Shinbo et al. “Study on Quantitative Evaluation of Biological Habitat Environment in Tidal Flats: Targeting Polychaete”, Journal of Japan Society of Civil Engineers, Coastal Engineering, Vol. 48, p1321-1325

  However, conventional artificial tidal flat conservation / regeneration methods only select the particle size of the tidal flat sediment from the viewpoint of providing a suitable bottom sediment for the organism to be cultivated. There is a problem that does not consider other factors related to the habitat and growth of organisms, especially the food chain. In natural tidal flats and shallow waters, zooplankton is eaten by zooplankton, and these plankton are eaten by crustaceans such as crabs, polychaetes such as sandworms, fry and small fish such as mahaze and eel, and large fish and birds. A food chain is formed. In order to sustain a rich coastal area continuously, it is important to cultivate various organisms that form a food chain without bias.

  For example, in order to inhabit mahaze and eel, which are representative species of Japan as natural fishery resources in the coastal areas and shallow areas, it is necessary to promote the growth of small animals such as shellfish, crustaceans, and polychaetes that serve as food. Furthermore, the growth of plankton, which is the food for these small animals, is necessary. In other words, even if specific organisms such as mahaze and eel are intended to be inhabited, it is not sufficient to simply make the bottom sediment suitable for these organisms, but various organisms that constitute the food chain related to that organism. It is necessary to create an environment that can inhabit.

  Accordingly, an object of the present invention is to provide an artificial tidal flat construction method and a synthetic tidal flat having a function of continuously maintaining the natural food chain.

  The present inventor has paid attention to natural tidal flats and shallow thermal environments, particularly water temperature. It is known that tidal flats and shallow fields are susceptible to heat from the atmosphere because the water depth is extremely shallow, but the present inventor has found that the water temperature off the tidal flat is more than the temperature of the atmosphere (temperature) by examining natural tidal flats. From late March to mid-June, when the temperature was low, we found that the water temperature of the tidal flat was higher than the atmospheric temperature. Table 1 shows the survey results showing the relationship between water temperature and air temperature in the tidal flats of Tokyo Bay from January to August and off the tidal flats.

  Small animals such as plankton, crustaceans, and polychaetes that inhabit in tidal flats are variable temperature animals whose body temperature changes according to the temperature of the outside world, and their growth and proliferation are promoted by rising seawater temperature. As shown in Table 1, in natural tidal flats, the growth and proliferation of the plankton and small animals are promoted from spring to summer by increasing the water temperature from March to June by about 2-8 ° C compared to the water area outside the tidal flat. The ecology of tidal flats is about 100 to 1000 times higher than the waters outside the tidal flats. It is thought that the food chain by various organisms in natural tidal flats is a result of the thermal environment of such tidal flats.

  The present inventor has found that one of the factors causing the tidal flat water temperature to be higher than the temperature is absorption of solar radiation by the tidal flat sediment. In the tidal flat, the tidal flat ground that has been dried out during low tides is warmed by the sun, and the seawater that pushes over the dry ground is gradually warmed. The seawater temperature of the tidal flat becomes higher than the temperature due to the repetition of the solar radiation heat absorption of the tidal flat ground by this tidal change and the heat transfer from the bottom of the tidal flat to the seawater. Furthermore, the present inventor has found that the wet color of the tidal flat sediment is important in order to increase the seawater temperature of the tidal flat, and as a result of further research and development based on this knowledge, the present invention has been completed. It is a thing.

  Referring to the embodiment of FIG. 1, the artificial tidal flat construction method of the present invention has a high solar radiation absorption rate when wet in the intertidal zone on the coastal soil 6 that gently slopes over the intertidal zone. Tidal flat bottom soil 10 is used as the soil, and the temperature of coastal sea water 1 is increased by repeating solar radiation heat absorption of bottom soil 10 at low tide and heat transfer from bottom soil 10 to seawater 1 at high tide. It will be.

  In addition, referring to the embodiment of FIG. 1, the artificial tidal flat of the present invention is composed of coastal soil 6 laid with a gentle slope over the intertidal zone, and solar radiation when the soil is wet in the intertidal zone of the coastal soil 6 The tidal flat bottom soil 10 has a high color absorption rate, and it absorbs the radiant heat of the bottom soil 10 at low tide and repeats heat transfer from the bottom soil 10 to seawater 1 at high tide. The temperature of the seawater 1 is increased.

  Preferably, the wetness of the tidal flat sediment 10 is closer to black than white. The tidal flat bottom soil 10 can have a particle size suitable for inhabiting tidal flat organisms, and the color of the bottom soil 10 can be adjusted by mixing carbon particles, pigment-mixed concrete particles and / or sulfide-mixed dredged soil.

  More preferably, the coastal soil 6 is surrounded by the wave-dissipating wall 4 with an opening, and the temperature of the seawater 1 in the wave-dissipating wall 4 is increased while suppressing waves from outside the wave-dissipating wall 4 to the coastal soil 6. In this case, it is desirable that the sea level area at low tide in the wave-dissipating wall 4 is 40% or less of the sea level area at high tide. Further, the wave-dissipating wall 4 is made of a material having a high solar radiation absorption rate when wet, and the temperature of the coastal seawater 1 can be increased by the solar radiation heat absorbed by the wave-dissipating wall 4.

  The artificial tidal flat construction method and artificial tidal flat according to the present invention include a tidal flat bottom soil that has a high solar radiation absorption rate when wet in the intertidal zone on a coastal soil that gently slopes over the intertidal zone. The coastal seawater temperature is increased by repeating the solar radiation heat absorption of the bottom soil at low tide and the heat transfer from the bottom soil to seawater at the time of storm surge.

(B) A thermal environment close to natural tidal flats can be maintained, and the food chain necessary for the cultivation of tidal flats can be maintained continuously.
(B) The temperature of coastal seawater can be increased from spring to summer, and the growth and proliferation of plankton and small animals constituting the lower and middle of the food chain can be significantly promoted.
(C) It can be expected to contribute to the regeneration of coastal areas rich in marine resources because it can sustain the habitat of fish such as mahaze and eels with plankton and small animals.

  FIG. 1 shows an embodiment in which the present invention is applied to the maintenance and regeneration of a straight coastline in contact with an upright revetment 3. In the illustrated example, the coastal soil 6 is laid down on the sea side of the revetment 3 in the direction of going offshore from the shore 2 and the coastal soil 6 is laid, and the intertidal zone of the coastal soil 6 (the region between the high tide line HWL and the low tide line LWL). ) Tidal flat bottom soil 10, which has a high color of solar radiation absorption when wet, is available. However, the present invention is not limited to the application to the artificially constructed coastal soil 6, and for example, it can be expected that the present invention is applied to the natural coastal soil 6 in which the ecosystem is weakened to preserve and restore the tidal flat. .

  As the tidal flat bottom soil 10, a material whose brightness is closer to black than white when water is discolored can be used. As a result of investigating a natural tidal flat using Kodak's Gray Scale (black scale divided into black, 0 white and 100 achromatic colors), the lightness of the tidal flat bottom soil 10 is wet. I found it to be 50 or less. For example, the lightness of the sediment in the Ariake Sea tidal flat is about 56 to 61 in a dry state, but it is about 37 to 40 when moisture is included. Moreover, in the natural tidal flats in the Hayama area, the lightness of the sediment is about 67 to 74 in the dry state, and about 43 to 47 in the wet state. In tidal flats that repeat tides, the lightness when wet is important for the formation of a thermal environment.

  The mudflat bottom soil 10, which has a lightness of 50 or less when wet, is exposed to the atmosphere at low tide and absorbs solar radiation to become high temperature. The absorbed heat is transferred to the seawater 1 that is flooded at high tide. Increase the temperature of coastal seawater 1. In the present invention, it is possible to adjust the rising temperature of the seawater 1 by appropriately designing the amount of heat absorbed by the tidal flat sediment 10 and the amount of seawater 1 that rushes at the time of storm surge. It can open the way to raise the water temperature so that the food chain necessary for the growth of the organism 11 can be maintained.

  The amount of heat absorbed by the tidal flat bottom soil 10 can be adjusted by the lightness of the tidal flat bottom soil 10 when wet. The lightness of the tidal flat bottom soil 10 when wet can be adjusted by mixing the appropriate granules that become blackish when impregnated.For example, carbon granules, pigment-mixed concrete granules, sulfide-mixed clay, etc. Can be adjusted by mixing. That is, the amount of heat absorbed by the tidal flat bottom soil 10 can be adjusted by the mixing amount of carbon particles and the like.

  Moreover, when the wave-dissipating wall 4 with an opening surrounding the coastal soil 6 is provided as shown in the illustrated example, the amount of the seawater 1 rushing at the time of high tide is calculated based on the sea level at high tide and the sea level at low tide inside the wave-dissipating wall 4. The area ratio can be adjusted. For example, when wind waves generated offshore against strong winds with a wind speed of 10 m or more rush to the tidal flat, the seawater 1 warmed by the tidal flat bottom soil 10 is cooled, and the thermal environment of the tidal flat may be destroyed. Therefore, it is desirable to form a water area that is hardly affected by offshore waves as shown in the illustrated example, and to maintain a thermal environment inside the wave-dissipating wall 4. In order to avoid the influence of waves, it is desirable that the size of the opening facing offshore of the inner water area of the wave breaking wall 4 is 50% or less of the length of the wave breaking wall 4 in contact with the sea surface. When the size of the opening is 50% or more, it becomes easy to be directly affected by waves, and the water temperature rise phenomenon is lowered.

  For example, the sea level area at low tide inside the wave-dissipating wall 4 is 40% or less of the sea level area at high tide. This 40% can include submarine trenches such as Miyoshi lines. Necessary to cultivate tidal flat organisms 11 inside the wave-dissipating wall 4 by placing the mud flat bottom soil 10 in over 60% of the portion to be dried and making it a portion that is heated by receiving radiant heat of sunlight. A thermal environment can be maintained. However, the ratio of sea level at low tide and high tide is not limited to this example. In winter, the temperature of the dried water is lowered and the entire water area is lowered. Natural tidal flats are warm from spring to summer and cool in winter, and organisms that inhabit in the high temperature period disappear in the low temperature period, creating a gap in the bottom of the tidal flat, and in the next high temperature period or spring. It will be the next generation breeding space. Such a natural selection system can be formed by lowering the temperature of the tidal flat in winter.

  The area ratio of the sea level at the time of low tide and high tide can be adjusted by, for example, the inclination angle when the coastal soil 6 is laid. In the illustrated example, the coastal soil 6 has a gentle inclination angle of about 1/100 to 1/200. However, the coastal soil 6 from the shore 2 to the seabed is inclined downward in a step shape of about 2 to 5 steps, for example. A plurality of staircase portions having different flood times may be provided between the high tide line HWL and the low tide line LWL. In this case, the tidal flat bottom soil 10 suitable for the tidal flat species adapted to each flooding time may be provided for each step portion.

For example, the habitat conditions of sandworms, one of the representative organisms in Japan's tidal flats, are: sediment particle size (median particle size D _{50 with} a passing mass percentage of 50%) 0.1 to 0.2 mm, mud fraction (particle size 0.074 There is a report that the mass ratio of silt / clay of less than mm is 15 to 20%, loss on ignition is 2.0 to 3.0%, and the water temperature is 29 ° C. (Non-patent Document 1). In the artificial tidal flat shown in FIG. 1, the inclination angle of the coastal soil 6 is determined so that the area ratio between the low tide and the high tide inside the wave-dissipating wall 4 is a required ratio, and mud and sand containing organic matter and humus soil. , Tidal flat bottom that has a lightness of 50 or more when wet with a suitable particle size, mud fraction and loss on ignition by mixing gravels with carbon particles, pigment-mixed concrete particles, sulfide-mixed clay, etc. By preparing the soil 10 and putting the bottom sediment 10 of the tidal flat into the low tide zone of the coastal soil 6, it can be expected that the seawater temperature of the tidal flat is maintained at a temperature suitable for the mussel.

  Further, when the wave-dissipating wall 4 is provided as in the illustrated example, the wave-dissipating wall 4 is made of a material having a color with a high absorption rate of solar radiation when wet, and is coasted by the solar radiation heat absorbed by the wave-dissipating wall 4. It can also be expected to increase the seawater temperature. For example, the wave-dissipating wall 4 may be made of a dye-mixed concrete that has a lightness of 50 or less when wet, and the lightness when wet may be adjusted by the amount of the mixed dye. Moreover, although it becomes difficult to adjust the color, the wave-dissipating wall 4 may be a natural stone of an appropriate color.

  According to the present invention, it is possible to maintain a thermal environment close to natural tidal flats, and thus it is possible to continuously maintain a food chain necessary for the cultivation of tidal flat organisms 11. Species that make up the lower and middle parts of the food chain, such as bacteria, bacteria, algae containing phytoplankton such as diatoms and green algae that grow on the sediment, and zooplankton, shellfish, crustaceans, and polychaetes that keep them The growth of animals such as mosquitoes can be expected. Therefore, it is possible to make a tidal flat where fish such as mahaze and eel that keep these algae and animals can live continuously, and it can be expected to contribute to the regeneration of coastal and coastal areas rich in these marine resources.

  Thus, it is possible to achieve the object of the present invention, “an artificial tidal flat construction method and artificial tidal flat having a function of continuously maintaining the natural food chain”.

  In addition, the tidal flat bottom soil 10 and the wave-dissipating wall 4 having a lightness of 50 or less when wet not only absorb solar radiation and become high temperature, but also have an effect of reducing reflection of sunlight, particularly ultraviolet rays. Therefore, according to the present invention, when the tidal flat bottom soil 10 has a lightness of 50 or less when wet, it is possible to make the tidal flat bottom soil 10 suitable for inhabiting small animals with little reflection.

  In the embodiment of FIG. 1, sandy soil 12 having a particle size suitable for the growth of the wet plants 13 is provided in a portion of the coastal soil 6 that is higher than the storm surge line HWL and is not flooded. In order to regenerate the coastal area where various organisms can inhabit, not only the tidal flats where the tidal flat organisms 11 live, but also reeds, nagamino-onishiba, kusayoshi, eagle, stigmata, fukudo, uragiku, shiragoku, oysters, etc. It is desirable to form a habitat for the wet plants 12 (hereinafter referred to as Yoshihara). For example, soil with a particle size of about 0.2 mm is preferred for reeds, and it has been reported that it is inappropriate for gravel and rocks that are too large, silt and clay that are too small. For this reason, when reeds inhabit on the coastal soil 6, sandy soil having a particle size of about 0.02 to 0.3 mm is provided at a site higher than the intertidal zone of the coastal soil 6.

  Moreover, in natural reed fields, fresh water is supplied as groundwater from the hinterland, and a brackish water area where fresh water and seawater 1 are mixed is formed. In the example shown in the figure, fresh water 16 is supplied from the shore side of sandy soil 12 to form a brackish water area where fresh water 16 and seawater 1 cross on sandy soil 12, and the portion higher than the storm tide HWL It is said. However, if the supply amount of fresh water 16 is too large, the seawater 1 will be cooled and the thermal environment of the tidal flat will be destroyed. Therefore, the supply amount of fresh water 16 should be within 20% of the total water area inside the wave-dissipating wall 4. Is desirable.

  Further, in the illustrated example, the bottom soil 14 of the algae ground suitable for algae inhabit is provided at a site lower than the low tide line LWL on the coastal soil 6. It is possible to cultivate multiple biological habitats such as reed fields, tidal flats, and algae beds on the coastal soil 6 on the coastal soil 6. The development of a nearby healthy coastal area can be expected. If necessary, the sandy soil 12, the tidal flat bottom soil 10, and the seaweed bed bottom soil 14 on the coastal soil 6 may be earthed using semi-structures such as wooden piles and rocks. .

  In FIG. 2, a revetment 3 of a color having a high solar radiation absorption rate is provided on the shore 2 in contact with the sea surface, a wave-dissipating wall 4 is provided in parallel with the shore 2, and the shore 2 is interposed between the revetment 3 and the wave-dissipating wall 4. An embodiment in which the present invention is applied to coastal soil 6 laid down and inclined along the line is shown. Since the present invention requires a tidal flat bottom soil 10 that absorbs solar radiation and has a gentle slope, for example, when the water area in front of the seaside of the revetment 3 is narrow, the method of FIG. May be difficult. In the embodiment of FIG. 2, the coastal soil 6 is laid along the shore instead of the direction from the shore toward the shore. By creating a tidal flat in parallel with the shore in this way, even if the water area on the front of the revetment is narrow, the tidal flat sediment 10 having a suitable slope can be provided on the front of the revetment 3.

  In the embodiment of FIG. 2, not only the above-described wave breaker wall 4 but also the revetment wall 3 is made of a material having a color with a high absorption rate of solar radiation when wet, so that the sun absorbed by the wave breaker wall 4 and the revetment wall 3 is absorbed. It can also be expected to increase the seawater temperature along the coast by radiant heat. In this case, the revetment 3 can be made of the same pigment-mixed concrete as the wave-dissipating wall 4 described above, and the brightness when wet can be adjusted by the amount of the pigment to be mixed.

  In FIG. 2, as shown in FIG. 3, a backfilling material 20 such as chestnut, sand, earth and sand, silt, high quality soil, shells, and concrete waste is provided between the revetment 3 and the shore. In addition, it is desirable to pierce the through hole 21 in the thickness direction as a biological entrance. Seawater 1 enters the backfill material 20 from the through-hole 21 at high tide, and the seawater 1 gradually flows out from the backfill material 20 to the through-hole 21 at low tide, so the backfill material 20 is suitable for living organisms. Can be maintained. In addition, by making the revetment 3 made of a material with a high solar radiation absorption rate, the reflection of ultraviolet rays from the surface of the revetment 3 is suppressed, and small animals such as crabs enter the backfilling material 20 through the through-hole 21 and backfill. It is possible to fix crabs and the like using the gaps between stones in the material 20 and holes dug in the earth and sand as habitats. The land portion from the top of the revetment 3 is also made of a moistening material such as a retaining structure, and a living space for land-inhabiting crabs can be provided at the joint of the retaining space.

  FIG. 4 shows an example of an artificial wetland constructed using the present invention. According to the present invention, it is possible to create a coastal area where fish such as mahaze and eel can continuously inhabit, and as shown in FIG. By providing the road 6 and the like, it is possible to create a rich coastal area where humans who use mahaze and eels inhabiting artificial wetlands can be familiar as marine resources.

It is explanatory drawing of one Example of this invention. It is explanatory drawing of the other Example of this invention. It is an example of sectional drawing of the revetment used in FIG. It is explanatory drawing of other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Seawater 2 ... Shore 3 ... Revetment 4 ... Wave breaker wall 5 ... Artificial river 6 ... Sidewalk and cycling road 8 ... Plant
10 ... Tidal flat sediment 11 ... Tidal flat organisms
12 ... Sandy soil 13 ... Hygrophytes
14 ... Algae bottom sediment
16 ... Freshwater
20 ... Backfill material 21 ... Biological entrance / exit

Claims (16)

Tidal flat bottom soil that has a high solar radiation absorption rate when wet is applied to the intertidal zone on the coastal soil that gently slopes above and below the intertidal zone, and solar radiation heat absorption of the bottom soil at low tide Of artificial tidal flats in which coastal seawater temperature is increased by repeated heat transfer from the sediment to seawater at high tide. The method for creating an artificial tidal flat according to claim 1, wherein the lightness of the tidal flat bottom soil when wet is made closer to black than white. 3. The creation method according to claim 2, wherein the tidal flat sediment is made to have a particle size suitable for inhabiting tidal flat organisms, and the color of the sediment is mixed with carbon particles, pigment-mixed concrete particles and / or sulfide-mixed dredged soil. Artificial tidal flat construction method that is adjusted. 4. The creation method according to claim 1, wherein a sandy soil having a particle size suitable for the growth of wet plants is formed on the coastal soil higher than the intertidal zone, and the sandy material from the shore side of the sandy soil. A method for creating artificial tidal flats by supplying fresh water to the ground. 5. The artificial method according to claim 1, wherein the coastal soil is surrounded by a wave-dissipating wall with an opening, and the seawater temperature in the wave-dissipating wall is increased while suppressing waves from outside the wave-dissipating wall to the coastal soil. How to create a tidal flat. 6. The method for creating an artificial tidal flat according to claim 5, wherein the sea surface area at low tide in the wave-dissipating wall is 40% or less of the sea surface area at high tide. The creation method according to claim 5 or 6, wherein the wave-dissipating wall is made of a material having a color with a high absorption rate of solar radiation when wet, and the coastal seawater temperature is increased by solar radiation heat absorbed by the wave-dissipating wall. How to create an artificial tidal flat. 8. The creation method according to claim 5, wherein a revetment of a color having a high absorption rate of solar radiation is provided on a shore in contact with the sea surface, the wave-dissipating wall is provided in parallel with the shore, and the coastal soil is revetd and wave-dissipated. A method for creating an artificial tidal flat, which is laid down and inclined along the shore between the walls, and the seawater temperature between the revetment and the wave-dissipating wall is increased by the solar radiant heat absorbed by the revetment. 9. The method of creating an artificial tidal flat according to claim 8, wherein a backfilling material serving as a living place is provided between the shore and the revetment, and a through-hole in a thickness direction is formed in the revetment as a biological entrance. Coastal soil laid with a gentle slope over the upper and lower intertidal zones, and tidal flat sediments with a high color of solar radiation absorption when wet, in the intertidal zone of the coastal soil, and the bottom at low tide An artificial tidal flat where the temperature of coastal seawater is increased by repeating solar radiation heat absorption from the soil and heat transfer from the bottom soil to seawater during storm surges. The artificial tidal flat according to claim 10, wherein the lightness of the bottom sediment of the tidal flat is made closer to black than white. The artificial tidal flat according to claim 11, wherein the tidal flat bottom soil has a particle size suitable for inhabiting tidal flat organisms and is mixed with carbon particles, pigment-mixed concrete particles and / or sulfide-mixed dredged soil. The artificial tidal flat according to any one of claims 10 to 12, wherein a wave-dissipating wall with an opening surrounding the coastal soil is provided. The artificial tidal flat according to claim 13, wherein the sea surface area at low tide in the wave-dissipating wall is 40% or less of the sea surface area at high tide. 15. The artificial tidal flat according to claim 13 or 14, wherein the wave-dissipating wall is made of a material having a color with a high absorption rate of solar radiation when wet. The artificial tidal flat according to any one of claims 13 to 15, wherein a revetment of a color having a high solar radiation absorption rate is provided on a shore in contact with the sea surface, the wave-dissipating wall is provided in parallel with the shore, and the coastal soil is reveted and wave-dissipated. An artificial tidal flat laid down along the shore between the walls.

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