A method for constructing a coastal plant dune

Abstract

The present invention provides a method for constructing a coastal plant dune, comprising: arranging a plurality of dune protection belts on the beach in the upper-middle part of the high tide zone or the supratidal zone, wherein the protection belt includes an outer layer close to the sea, an inner layer close to the coast, and a stacking area formed by the outer layer and the inner layer; sand passes through the outer layer and enters the stacking area, until a dune with a target diameter and a target height is formed in the stacking area, and then at least two belts of vegetation are planted on the dune according to the salt tolerance level from the sea to the land to form a shrub dune, wherein the shrub dune can settle the sand carried in the wind or sea water, and can continuously accumulate the dune with the growth of the vegetation. The method of the present invention uses artificial intervention to quickly construct the dune, which has a positive effect on the formation and stability of the shrub and grass dune, and has the functions of wave dissipation and shore protection for the eroded sandy coast.

Description

Technical Field

[0001] The present invention relates to the technical field of coastal protection, and in particular to a method for constructing a coastal plant dune. Background Art

[0002] Erosion exists in many sandy coasts in China, which affects the life and property safety of people in villages, aquaculture facilities, etc. behind the coast. Traditional coastal protection methods mainly rely on physical barriers such as sea walls and breakwaters. These methods are often costly and have an impact on the ecological environment. Coastal dunes are important geomorphic units of sandy coasts. They can not only play a "flexible" protection role against extreme marine dynamics, but also provide valuable living space for coastal animals and plants. At present, there are many artificial dune restoration methods. For example, CN116368983A, a method for coastal dune restoration and maintenance. However, this method has the following problems: the project volume is relatively large, and the artificially piled dunes are easily carried away by the wind or waves; another example is CN219612681U, a windproof and sand-blocking structure for coastal dune replanting, and CN114258815A, a rapid sand fixation and treatment method for mobile dunes. These two methods only consider the influence of wind and sand, but do not consider the influence of water flow and waves on the dunes; another example is CN116377946A, an ecological restoration method for optimizing the vegetation combination of sandy coasts. However, this method lacks specific and operable methods for the plant species, layout, planting, and maintenance measures adopted. Different plants have differences in the elevation and flooding degree they adapt to in the coastal area, which affects the growth of plants. Therefore, in view of the problems existing in the above-mentioned prior art, a method for constructing a coastal plant dune is designed. Summary of the Invention

[0003] Aiming at the deficiencies existing in the prior art, the present invention provides a method for constructing a coastal plant dune, which can effectively solve the above problems.

[0004] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0005] The present invention provides a method for constructing a coastal plant dune, including:

[0006] Set a plurality of dune protection belts on the beach in the upper-middle part of the high tide zone or the supratidal zone. Among them, the protection belt includes an outer layer close to the sea, an inner layer close to the coast, and a stacking area formed by the outer layer and the inner layer;

[0007] Sand passes through the outer layer and enters the stacking area. After a dune with a target diameter and a target height is formed in the stacking area, at least two levels of vegetation belts are planted on the dune according to the salt tolerance level from the sea to the land to form a shrub dune. The shrub dune can settle the sand carried in the wind or sea water and can continuously accumulate the dune with the growth of the vegetation;

[0008] Among them, the spacing of the dune protection belts is S = W × 0.75, where W is the desired bottom width of the dune; the height of the dune protection belts Ha = 0.3 × D, where D is the desired maximum height of the dune; the number of the dune protection belts N = coastline length / (W + S), and (W + S) is the space occupied by each dune protection belt.

[0009] The position of the dune protection belt in the high-tide zone is pi = L + (H - L) × 0.6; the position of the dune protection belt in the supratidal zone is ps = H + 0.5 × D; L is the height of the mean neap high tide line, H is the height of the mean spring high tide line, and (H - L) is the height range of the coastal high-tide zone.

[0010] As a further improvement, the dune construction device includes: a plurality of the dune protection belts are arranged in a plum blossom shape on the beach.

[0011] As a further improvement, the dune protection belt includes: a plurality of fixing piles, a thick mesh group, a fine mesh group, and a fixing member group. The fixing piles are fixed on the beach, the thick mesh group is arranged on the fixing piles to form the outer layer, and the fine mesh group is arranged on the fixing piles to form the inner layer.

[0012] As a further improvement, the thick mesh group is sequentially provided with a third thick mesh, a second thick mesh, and a first thick mesh from top to bottom.

[0013] As a further improvement, the mesh number of the third thick mesh is 40 - 50 meshes, the mesh number of the second thick mesh is 30 - 40 meshes, and the mesh number of the first thick mesh is 20 - 30 meshes.

[0014] As a further improvement, the fine mesh group is sequentially provided with a second fine mesh and a first fine mesh from top to bottom.

[0015] As a further improvement, the mesh number of the second fine mesh is 50 - 60 meshes, and the mesh number of the first fine mesh is 60 - 70 meshes.

[0016] As a further improvement, coastal herbaceous plants are planted on one side of the dune close to the outer layer, and salt-tolerant shrubs are planted on one side of the dune close to the inner layer.

[0017] As a further improvement, the coastal herbaceous plants are one or more of Sesuvium portulacastrum, Ipomoea pes-caprae, Oenothera drummondii, Wedelia prostrata, Cynodon dactylon, Sporobolus virginicus; the salt-tolerant shrubs are one or more of Clerodendrum inerme, Vitex rotundifolia, Casuarina equisetifolia, Scaevola sericea.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present invention designs the position, arrangement mode, height of the protective belt, and elevation of the sand dunes, so that the formed sand dunes can effectively reduce the impact of sea waves on the coast, play a good role in protecting the stability of the coast, and the formed sand dunes are stable and not easily damaged by wind or sea water; the sand dune protective belt set has a strong ability to capture sand, the surface of the sand dune is covered with plants, and after the plants grow, they have a certain sand fixation effect. After the plants grow, the sand carried by the wind will settle in the plant clusters, causing the sand dunes to gradually pile up. At the same time, the plants will also drill out from the new sand surface and continue to grow upward, and the sand dunes will continue to pile up in the plant clusters, thus forming shrub sand dunes; and by using the method of artificial intervention, sand dunes are quickly constructed, and plants are quickly made to grow and cover the surface of the sand dunes, which has a positive effect on the formation and stability of the shrub sand dunes.

[0020] 2. The present invention sets the sand dune construction device to adopt a combination of fixed piles, a thick mesh group, and a fine mesh group, which can effectively form stable sand dunes inside the enclosure net and is conducive to planting plants in the sand dunes. The fixed piles and the enclosure net will not affect the growth of plants; the fixed piles are provided with foldable and deployable grips, which are convenient for inserting the fixed piles into the sand. The first hook ring and the second hook ring provided on the fixed piles are conducive to using fixing parts to fix the enclosure net on the fixed piles to prevent the enclosure net from being peeled off from the fixed piles by wind or sea waves; a thick mesh group is set on the side close to the ocean to filter the sand carried by the wind or sea waves, allowing sand grains to enter the enclosure net and blocking stones or other sundries outside. The stones blocked outside the thick mesh group also contribute to improving the stability of the device during long-term accumulation. A fine mesh group is set on the side far from the ocean to prevent the sand grains inside the enclosure net from being blown away by the wind or carried away by the sea waves, which is conducive to the accumulation of sand dunes. When the accumulation height of the sand dunes exceeds the enclosure net, it can continue to expand outward until the device is wrapped inside; and the sand dunes are arranged in a plum blossom shape, which is conducive to weakening the energy of the sea waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a schematic structural diagram of a method for constructing a coastal plant sand dune of the present invention.

[0023] Figure 2 It is a schematic diagram of the sand dune distribution of a method for constructing a coastal plant sand dune of the present invention.

[0024] Figure 3 It is a schematic diagram of the early stage of sand accumulation of a sand dune in a method for constructing a coastal plant sand dune of the present invention.

[0025] Figure 4 It is a schematic diagram of the middle stage of sand accumulation of a dune in a method for constructing a coastal plant dune of the present invention.

[0026] Figure 5 It is a schematic diagram of the late stage of sand accumulation of a dune in a method for constructing a coastal plant dune of the present invention.

[0027] Figure 6 It is a schematic diagram of a dune construction device in a method for constructing a coastal plant dune of the present invention.

[0028] Figure 7 It is a schematic diagram of the structure of a fixing pile in a method for constructing a coastal plant dune of the present invention.

[0029] Figure 8 It is a schematic cross-sectional view of the structure of a fixing pile in a method for constructing a coastal plant dune of the present invention.

[0030] Figure 9 It is a schematic diagram of the usage state of a fixing pile in a method for constructing a coastal plant dune of the present invention.

[0031] Figure 10 It is a schematic diagram of the connection state of a fixing pile in a method for constructing a coastal plant dune of the present invention Figure 1 。

[0032] Figure 11 It is a schematic diagram of the connection state of a fixing pile in a method for constructing a coastal plant dune of the present invention Figure 2 。

[0033] In the figure: 1 - fixing pile, 11 - main body, 111 - drill bit, 112 - handle groove, 12 - mesh hole, 13 - first hook ring, 14 - second hook ring, 15 - grip, 2 - thick mesh group, 21 - first thick mesh, 22 - second thick mesh, 23 - third thick mesh, 3 - fine mesh group, 31 - first fine mesh, 32 - second fine mesh, 4 - fixing member group, 41 - first fixing member, 42 - second fixing member. Specific embodiments

[0034] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0036] Referring to Figures 1-5 as shown, a method for constructing a coastal plant dune includes:

[0037] Setting a plurality of dune protection belts on the beach in the upper-middle part of the high tide zone or the supratidal zone, wherein the dune protection belt includes an outer layer close to the sea, an inner layer close to the coast, and a stacking area formed by the outer layer and the inner layer;

[0038] After the sand passes through the outer layer and enters the stacking area until a dune with a target diameter and a target height is formed in the stacking area, according to the seawater salinity in the area where the dune is located and the elevation of the dune, at least one kind of vegetation is planted on the dune according to the salt tolerance of the plants to form a grassy or shrubby dune. The selected plants have the abilities of salt tolerance, sand fixation and sand burial resistance, can promote the settlement of the sand carried in the wind or seawater, and can continuously accumulate the dune with the growth of the vegetation. The plant planting is mainly carried out with bagged seedlings, and cuttings can also be planted in the rainy season, combined with the method of sowing seeds;

[0039] Among them, the position of the dune protection belt in the high tide zone is pi = L + (H - L) × 0.6; the position of the dune protection belt in the supratidal zone is ps = H + 0.5 × D; L is the height of the mean neap high tide line, and the mean high tide line refers to the highest value that seawater can reach under normal weather conditions. H is the height of the mean spring high tide line, and the mean spring high tide line refers to the highest value that seawater can reach under extreme weather conditions. (H - L) represents the height range of the coastal high tide zone. The protection belt is placed at 60% of the total height of the high tide zone to avoid setting the position of the protection belt too low to reduce the situation of being completely submerged by seawater. However, it cannot be set too close to the supratidal zone to ensure there is enough space to intercept sand. H + 0.5 × D refers to the space that is half of the expected dune height higher above the mean spring high tide line, ensuring that the protection belt is above the spring high tide line, reserving enough space for the growth of dunes, and enabling the subsequent formed dunes to effectively weaken the waves.

[0040] The spacing of the dune protection belts is S = W × 0.75, where W is the expected bottom width of the dunes; the height of the dune protection belts is Ha = 0.3 × D, where D is the expected maximum height of the dunes; the number of dune protection belts N = coastline length / (W + S), where the coastline length refers to the total length of the coast to be protected, and (W + S) is the space occupied by each dune protection belt. The spacing of the dune protection belts is set to 75% of the expected dune width. Also, since the dune protection belts are arranged in a plum blossom pattern on the beach, there will be overlapping parts between each dune protection belt to enhance the effect of capturing sand and reserve a certain space for the natural development and expansion of the dunes. Setting the height of the protection belts to 30% of the expected dune height is conducive to the initial formation of the dunes, and the formed dunes have good stability and are not easily damaged by wind or seawater, which is beneficial to the subsequent growth of the dunes.

[0041] Furthermore, the present invention first determines the mean spring high tide line H and the mean neap high tide line L of the beach area where the dunes need to be constructed, and selects the types of vegetation to be planted according to the salinity of the beach.

[0042] Furthermore, a plurality of dune protection belts are arranged along the supratidal zone or the high-tide zone of the beach. The plurality of dune protection belts are generally arranged in a plum blossom pattern along the supratidal zone of the beach or at the upper-middle position of the high-tide zone. The dune protection belts form circular, semi-circular and crescent-shaped docking areas through the combination of the outer layer close to the sea and the inner layer close to the coast. The outer layer of the dune protection belt is used to allow the sand in the wind or sea water to enter the accumulation area. Therefore, when setting the outer layer, a windward side needs to be set, while the inner layer is set on the leeward side to retain the sand in the accumulation area. Dunes are gradually formed by accumulation within the dune protection belt. Vegetation is planted within the dune protection belt, which is beneficial to the early growth of the vegetation, enabling the vegetation to take root in the dunes and not be easily washed away by the wind or sea water. And with the growth of the vegetation, more sand can be settled, continuously expanding the area and height of the dunes, thereby achieving a better wave-dissipating effect.

[0043] Furthermore, due to the ebb and flow of the sea water, in order to prevent the dunes from being repeatedly scoured by the sea water during the accumulation process, resulting in the inability to accumulate sand, therefore, the normal high-tide values of this sea area over the years are statistically analyzed to obtain the average spring high-tide line H and the average neap high-tide line L of this sea area. Based on this, the dune protection belt at the high-tide zone is set at pi = L + (H - L) × 0.6, that is, the dune protection belt is set at 60% of the total height of the high-tide zone, which is beneficial to the accumulation of sand, reducing the formation of dunes being unable to accumulate due to being submerged by sea water. And when a proper amount of sea water enters the dune protection belt, the sand can be more stable, making the formation speed of the dunes faster.

[0044] Furthermore, considering that during storms or extreme high tides, the sea tide will be higher than the average spring high-tide line, therefore, the extreme high-tide values of the sea water in this sea area over the years are statistically analyzed to obtain the height H of the average spring high-tide line of this sea area. Based on this, the dune protection belt at the supratidal zone is set at ps = H + 0.5 × D, that is, the dune protection belt is set at a position half of the expected dune height higher than the average spring high-tide line, to ensure that the dunes can still play a role in weakening the sea waves under extreme conditions and fully resist the erosion of ocean dynamics.

[0045] Furthermore, the spacing between each dune protection belt is S=W×0.75, and the height of the dune protection belt is Ha=0.3×D. The spacing of the dune protection belts is set to 75% of the expected dune width, and the multiple dune protection belts are generally arranged in a plum blossom shape along the supratidal zone of the beach or along the middle and upper part of the high tide zone. Therefore, there will be overlapping parts between the dune protection belts, which is conducive to the capture of sand and the production and expansion of dunes. As the dunes expand, adjacent dunes can be connected together to form a dune belt. Setting the height of the protection belt to 30% of the expected dune height is conducive to the initial formation of dunes and the growth of planted vegetation. When the dune accumulation height in the dune protection belt reaches 1 / 2Ha, vegetation is planted on the dunes and watered appropriately. The growth of vegetation is conducive to the sedimentation of sand. At this time, the sand particles covering the surface of the vegetation are smaller, which is conducive to the vegetation to drill out of the sand and continue to grow after being buried in the sand until the height of the dune reaches the height of the dune protection belt. After that, the sand will continue to accumulate behind the inner layer to expand the range of the dune, while the outer layer of the dune protection belt is deposited with materials that cannot pass through the outer layer. However, through the expansion of the growth area of ​​vegetation, sand can also be accumulated outside the outer layer.

[0046] Furthermore, plants with strong salt tolerance are mainly planted on the sand dunes. Coastal herbaceous plants are planted on the side of the sand dunes close to the outer layer, and salt-alkali tolerant shrubs are planted on the side of the sand dunes close to the inner layer; the coastal herbaceous plants are one or more of seahorse teeth, saddle vine, seaside evening primrose, haloth chrysanthemum, dogtooth grass, and salt-field shrew tail millet, and the salt-alkali tolerant shrubs are one or more of bitter gourd, single-leaf vitex, thousand-headed casuarina, and grass pittosporum; a single plant can be planted on the sand dunes, or a combination of multiple plants can be planted, and the plant combination needs to consider its ecological function and landscape value. The plant species and configuration patterns suitable for the restoration of backshore sand land in my country refer to Appendix A and Appendix C of "Technical Methods for Vegetation Restoration of Backshore Sand Land on Beaches" (HY / T 0304-2021). Common plant combinations include: single-leaf vitex, saddle vine, bitter gourd, single-leaf vitex, seahorse teeth, saddle vine, etc.

[0047] Furthermore, the beach area between the average neap high tide line and the average spring high tide line is often flooded by sea water, so general plants cannot grow and the sand is highly mobile. Therefore, it is necessary to first build a dune protection belt to form sand dunes of a certain height and range. After the prototype of the sand dune is formed, seahorses with strong salt tolerance are planted on the upper line of the sand dunes. As the seahorses grow, the sand dunes will gradually expand and increase. After the upper part of the sand dunes is higher than the average spring high tide line, plants with strong salt tolerance, such as simple-leaved vitex and saddle vine, are planted on the surface of the sand dunes to further promote the sedimentation of sand and the expansion and stability of the sand dunes.

[0048] The sandy beach area between the mean high water spring line and the coast is generally not submerged by seawater, but is submerged during extreme weather such as typhoons. Therefore, the sand in this area is relatively dry and is extremely easy to be blown away by the wind. Thus, there are two construction methods for this area: One is to first construct a dune protection belt and then plant plants. There are many types of plants to choose from, such as Vitex rotundifolia, Clerodendrum inerme, Ipomoea pes-caprae, Sesuvium portulacastrum, and Acacia eburnea. Generally, a combination of shrubs and vines or herbs is used. Shrubs are not easily buried by sand during summer typhoons or winter strong winds and can still maintain the growth of some plants under extreme weather conditions. Vines or herbs have a large coverage, and usually have a good effect on promoting sand settlement and reducing sand loss. The combination of the two has a better effect on the formation and stability of dunes; The other is to first plant shrubs with a certain height, use the plants to block the sand and gradually accumulate to form dunes. On the side of the dune close to the mean high water spring line, Vitex rotundifolia with strong salt tolerance is preferably selected, and on the side close to the coast, Vitex rotundifolia and Clerodendrum inerme can be selected for planting. When the height of the dune reaches 50 cm, vines or herbs such as Ipomoea pes-caprae, Acacia eburnea, and Sesuvium portulacastrum are further planted. Sesuvium portulacastrum is mainly planted on the side close to the ocean, and Ipomoea pes-caprae and Acacia eburnea are mainly planted on the side close to the land. Planting vines and herbs increases the vegetation coverage rate on the surface of the dune, promotes the expansion of the dune and reduces sand loss.

[0049] Furthermore, referring to Figures 6-11 as shown, it is the dune protection belt in the present invention, which includes: fixing piles 1, thick net groups 2, thin net groups 3, and fixing part groups 4.

[0050] The fixing piles 1 are fixed on the sandy beach. The thick net groups 2 are threaded between adjacent multiple fixing piles 1 and are arranged on the side close to the ocean. The thick net groups 2 form the outer layer of the dune protection belt; the thin net groups 3 are threaded between adjacent multiple fixing piles 1 and are arranged on the side far from the ocean. The thin net groups 3 form the inner layer of the dune protection belt; the thick net groups 2 and the thin net groups 3 are combined to form the enclosure net of the dune protection belt; fixing part groups 4 are arranged between the fixing piles 1 and the thick net groups 2, and between the fixing piles 1 and the thin net groups 3. The thick net groups 2 and the thin net groups 3 enclose to form an accumulation area for dune formation; by adopting the method of combining the fixing piles 1 with the thick net groups 2 and the thin net groups 3, stable dunes can be effectively accumulated within the enclosure net, and it is beneficial to plant plants in the dunes.

[0051] Further, in order to fix the device on the beach and prevent it from being blown away by the wind or knocked down by the waves, a fixing pile 1 is provided, which includes: a main body 11, a mesh hole 12, a first hook 13, a second hook 14 and a grip 15; the main body 11 is arranged in a column shape, one end of the main body 11 is provided with a drill bit 111, the other end of the main body 11 is provided with a handle groove 112, and two groups of grips 15 that rotate relative to each other are arranged in the handle groove 112. When the fixing pile 1 is not in use, the grips 15 are folded and stored in the handle groove 112. When the fixing pile 1 is in use, the two grips 15 rotate relative to each other to expand the grips 15 to a horizontal state, facilitating manual holding to insert the fixing pile 1 into the beach; a mesh hole 12 through which the enclosure net passes is axially penetrated through the main body 11, and multiple groups of first hooks 13 are oppositely arranged on the main body 11 near the mesh hole 12. In this embodiment, the first hooks 13 are arranged at the two short sides of the mesh hole 12, and a group of first hooks 13 is arranged at each of the two open ends of the mesh hole 12; a plurality of second hooks 14 are uniformly arranged along the axial direction on the side wall of the main body 11, and the second hooks 14 are arranged at the same height as the mesh hole 12. In this embodiment, three second hooks 14 are arranged at equal intervals, and three second hooks 14 are also arranged at the corresponding positions on the other side of the main body 11.

[0052] Further, in order to allow the sand outside the enclosure net to enter the enclosure net and block stones and sundries, a thick mesh group 2 is threaded between multiple fixing piles 1, and the thick mesh group 2 is arranged on the side close to the ocean. The wind and waves will first pass through the thick mesh group 2 and then enter the enclosure net and finally reach the fine mesh group 3. The sand grains carried by them will pass through the mesh holes on the thick mesh group 2 and enter the enclosure net, and the stones and sundries will be blocked outside the thick mesh group 2. The deposition of the stones and sundries outside the net can reinforce the stability of the device during the process; the thick mesh group 2 includes: a first thick mesh 21, a second thick mesh 22 and a third thick mesh 23. The upper end of the first thick mesh 21 is connected to the lower end of the second thick mesh 22, and the upper end of the second thick mesh 22 is connected to the lower end of the third thick mesh 23; the mesh number of the first thick mesh 21 is between 20 and 30 meshes, the mesh number of the second thick mesh 22 is between 30 and 40 meshes, and the mesh number of the third thick mesh 23 is between 40 and 50 meshes, so that the finally accumulated sand dunes are divided into three layers. The bottom layer has sands with different particle sizes, which is beneficial to the growth of the roots of the plants to be planted, enabling the plants to stably grow on the sand dunes. The smaller the particle size of the sand is towards the upper layer, which is beneficial for the plants to quickly drill out from the sand after being buried by the sand and continue to fix the sand.

[0053] Further, in order to prevent the sand entering the enclosure from being carried away by the wind and waves, a fine mesh group 3 is provided, and the fine mesh group 3 is arranged on the side away from the ocean. After the sand enters the enclosure, it will be blocked by the fine mesh group 3 in front of the net and will first accumulate in front of the net. The fine mesh group includes: a first fine mesh 31 and a second fine mesh 32. The upper end of the first fine mesh 31 is connected to the lower end of the second fine mesh 32. The mesh count of the first fine mesh 31 is 50-60 meshes, and the mesh count of the second fine mesh 32 is 60-70 meshes, which is beneficial to blocking most of the sand.

[0054] Further, in order to fix the coarse mesh group 2 and the fine mesh group 3 on the fixing pile 1, a fixing member group 4 is provided. The fixing member group 4 includes: a first fixing member 41 and a second fixing member 42. The first fixing member 41 makes the coarse mesh group 2 and the fine mesh group 3 in a straightened state by connecting to the first hook ring 13, which is beneficial to better blocking sand. The first fixing member 41 can be a double-headed hook or a rope; the second fixing member 42 is beneficial to the fixation of the coarse mesh group 2 and the fine mesh group 3 by connecting to the second hook ring 14, and prevents the coarse mesh group 2 and the fine mesh group 3 from being peeled off the fixing pile 1 by the wind or waves. Refer to Figures 9-11 As shown, there are three different layout methods of the present invention, namely circular, crescent-shaped and semi-circular, which can form dome-shaped sand dunes and crescent-shaped sand dunes, etc. The device is arranged in the upper-middle part or supra-tidal zone of the high tide zone of the beach. The sand dunes are generally arranged in a plum blossom shape along the upper-middle part or supra-tidal zone of the high tide zone of the beach, and the elevation of the bottom of the sand dunes is near or above the high tide line, and the elevation of the top of the sand dunes is higher than the spring high tide line; the finally formed shrub sand dunes are beneficial to the settlement of sand, can weaken the energy of the waves, and can achieve a better shore protection effect.

[0055] Further, the specific implementation manner of the present invention:

[0056] If plants such as Sesuvium portulacastrum and Ipomoea pes-caprae are planted, the sand dune protection belt is mainly enclosed in a circular shape, with a diameter of 1-2 m, and the height of the protection net is 50-100 cm. Plants are planted after the height of the sand dune accumulation reaches 30-50 cm. The plant seedlings used are bagged seedlings. The length of the Sesuvium portulacastrum seedlings is 20-30 cm, and the length of the Ipomoea pes-caprae seedlings is 50-80 cm, and the planting density is controlled at 25 plants / m 2 。

[0057] If plants such as Vitex trifolia var. simplicifolia and Clerodendrum inerme are planted, the shape of the sand dune protection belt can be circular, crescent-shaped, strip-shaped, etc. If a circular sand dune is set, the plants planted on the sand dune can be arranged in a circular, square or hexagonal pattern, and the diameter of the planting area is set at 2 - 5 m; if a crescent-shaped sand dune is set, the plants planted on the sand dune can be arranged in an arc or half-moon shape, and the diameter of the planting area is set at 3 - 8 m; if a strip-shaped sand dune is set, the plants planted on the sand dune can be arranged in a rectangular pattern, with a length set at 8 - 15 m and a width of 3 - 8 m. The strip-shaped sand dune is mainly set on the side close to the land. Vitex trifolia var. simplicifolia and Clerodendrum inerme are mainly planted with bagged seedlings, and bare-root seedlings can also be selected during rainy periods, with a height of 30 - 50 cm, and the planting density is controlled at 9 plants / m 2 .

[0058] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for constructing coastal plant dunes, characterized in that: include: A plurality of dune protection belts are arranged on a beach in the middle and upper part of a high tide zone or a supratidal zone. The plurality of dune protection belts are arranged in a plum blossom shape on the beach, and overlapping areas are arranged between the dune protection belts arranged staggered from each other, wherein the protection belts include an outer layer close to the sea and an inner layer close to the coast, and a stacking area formed by the outer layer and the inner layer. The dune protection belts are provided with a coarse mesh group (2) and a fine mesh group (3), wherein the coarse mesh group (2) is arranged on a fixed pile (1) to form the outer layer, and the fine mesh group (3) is arranged on the fixed pile (1) to form the inner layer; The sand passes through the outer layer and enters the accumulation area until a sand dune of a target diameter and a target height is formed in the accumulation area, and at least two belts of vegetation are planted on the sand dune from sea to land according to the salt tolerance level to form a shrub dune, wherein the shrub dune can settle the sand carried by the wind or sea water and can continuously accumulate the sand dune as the vegetation is generated; The spacing of the dune protection belts is S=W×0.75, where W is the desired width of the dune bottom; the height of the dune protection belt Ha=0.3×D, where D is the desired maximum height of the dune; the number of dune protection belts N=coastline length / (W+S), where (W+S) is the space occupied by each dune protection belt; The position of the dune protection zone in the high tide zone is pi=L+(HL)×0.6; the position of the dune protection zone in the supratidal zone is ps=H+0.5×D; L is the average height of the high tide line of neap tide, H is the average height of the high tide line of spring tide, and (HL) is the height range of the coastal high tide zone.

2. The method for constructing a coastal plant dune according to claim 1, characterized in that: The dune protection belt also comprises: a plurality of fixing piles (1) and a fixing member group (4), wherein the fixing piles (1) are fixed on the beach.

3. The method for constructing a coastal plant dune according to claim 2, characterized in that: The coarse mesh group (2) is provided with a third coarse mesh (23), a second coarse mesh (22) and a first coarse mesh (21) in order from top to bottom.

4. The method for constructing a coastal plant dune according to claim 3, characterized in that: The mesh size of the third coarse net (23) is 40-50 meshes, the mesh size of the second coarse net (22) is 30-40 meshes, and the mesh size of the first coarse net (21) is 20-30 meshes.

5. The method for constructing a coastal plant dune according to claim 2, characterized in that: The fine mesh group (3) is provided with a second fine mesh (32) and a first fine mesh (31) in sequence from top to bottom.

6. The method for constructing a coastal plant dune according to claim 5, characterized in that: The mesh size of the second fine net (32) is between 50 and 60 meshes, and the mesh size of the first fine net (31) is between 60 and 70 meshes.

7. The method for constructing a coastal plant dune according to claim 1, characterized in that: The sand dune is planted with coastal herbs on a side close to the outer layer, and the sand dune is planted with salt-alkali tolerant shrubs on a side close to the inner layer.

8. The method for constructing a coastal plant dune according to claim 7, characterized in that: The coastal herbaceous plants are one or more of seahorse, saddle vine, seaside evening primrose, hawthorn, dogtooth grass, and salt shrew tail millet; the salt-alkali tolerant shrubs are one or more of bitter orange, simple vitex, thousand-headed casuarina, and grass seahorse.

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