TITLE

STRUCTURE OF ARTIFICIAL AQUATIC PLANT DESCRIPTION

Technical Field of the Invention The present invention refers to the field of artificial aquatic plants, that is to say plants made of synthetic materials, basically conceived for installation on the marine floors with the aim of preventing coastal erosion . Background of the invention

It is well known how widespread and serious is the phenomenon of the coastal erosion, which in some cases is leading to an almost complete destruction of long strips of the sandy shores. The damage occurs along the sandy coasts, where the protective action of the groups of marine vegetation (seagrass) , and in particular of the meadows Posidonia oceanica, is being gradually reduced. As a matter of fact, the latter have suffered substantial deterioration, and withdrawal in the upper limit (that is the border closest to the dry land) , or they have been destroyed completely, due to various climatic reasons but above all due to human activities, especially pollution.

Currently, the techniques used for protecting the sandy shores against coastal erosion are mainly based on setting up emersed or immersed artificial barriers, made up of rocks or other materials which provide a rigid obstacle to the oncoming wave motion. However, the results are highly unsatisfactory, given that the waves easily tend to go over (in case of immersed barriers) or to literally get around (emersed barriers) the obstacle, substantially without encountering resistance against their erosive activity and, above all, against their

impact force.

In addition, there have been proposals to create artificial algae structures made of synthetic material, to be installed on the marine floor in place of the natural vegetation destroyed or reduced. Some examples regarding this solution are shown in the United States patents US 4221500, US4374629, US4478533, US4437786, US4490071, US4534675, US5876151, US6230654 and US6517282. However, the results obtained were disappointing, in that the proposed solutions are neither capable of fragmenting and thus weakening the wave front in a considerable manner before the latter reaches the coast, nor of withholding the sand transported by the wave, on its way offshore after hitting the coast. Summary of the invention

According to an aspect of the present invention, there is provided an artificial aquatic plant structure which, upon installation on the marine floor in proximity to the coast, is capable of ensuring an effective action of breaking the impact force which hits the coast itself, hence efficiently fighting the erosion.

According to another aspect of the invention, there is provided an artificial aquatic plant structure of the abovementioned type, which is also capable of withholding the sand that the wave motion tends to transport offshore taking it away from the sandy shore.

According to a further aspect of the invention, there is provided an artificial aquatic plant structure which is easy to construct, as well as inexpensive both in terms of realization and methods of installation.

According to a still further aspect of the invention, there is provided an artificial aquatic plant

structure which facilitates the establishment of marine animal and plant organisms in such a manner to restore the environmental conditions typical of the natural sea- grasses . The essential characteristics of the artificial aquatic plant structure according to the invention are defined by the first of the attached claims. Brief description of the drawings

Characteristics and advantages of the artificial aquatic plant structure according to the present invention shall be clearer from the following description of one of its embodiments, provided for exemplifying and non- limiting purposes with reference to the attached drawings, wherein: - figure 1 is an axonometric view of a single element of the artificial aquatic plant according to the invention; figure 2 is an axonometric view of a portion of a module of an artificial aquatic plant according to the invention, obtained by assembling a plurality of elements according to figure 1; and figures 3 and 4 show, analogously to figures 1 and 2, a variant embodiment of the structure according to the invention. Description of the preferred embodiments

Referring to the above figures, an artificial aquatic plant structure according to the invention is based on the association of single elements, each of which, shown separately in figure 1, comprise a bundle 1 of leaves 2 made of synthetic material, having characteristics - in terms of length, section, rigidity, flexibility - similar to the ones of the natural Posidonia

oceanica . Typically, but solely for exemplifying and non- limiting purposes, the plant can be about one meter long, about one centimeter wide and a few millimeters thick. The synthetic material used can be non-toxic polyethylene or other equivalent materials already used in the known art for manufacturing artificial algae.

The leaves 2 inside the bundle 1 may vary in number, but typically they can be in the range between five and ten, for example seven. The leaves 2 are mutually joined at a first end, intended to be at the lower part upon the installation of the bundle, as described hereinafter, while the stem, up to the other, second end, may bend freely in a manner varying from leaf to leaf. The junction between the leaves can be provided for by mechanical means (fastening, tying), gluing or melting.

The area about such junction is arranged inside a tubular sleeve 3, substantially rigid, such as to be subjected to no or negligible bending deformation, or else recover its non-deformed configuration in an elastic manner upon normal stresses generated on the sleeve by the wave motion when the same sleeve is in an immersed position .

The sleeve 3, advantageously made of the same synthetic material as the leaves 2 (with different thicknesses and possibly with a different density in such a manner to have greater stiffness with respect to the leaves), can for example be a few centimeters long, preferably in the range comprised between 10 and 50 cm and more preferably about 20 cm. Proportionally, the sleeve shall have an external diameter of a few centimeters, for example around 3 cm. Therefore, the sleeve 3 accommodates the bundle 1 of the leaves 2 closing around it for a

length starting from the first end. The stable engagement between the sleeve and the bundle can be provided for by mechanical means (simple fastening action), gluing or melting, thus also integrating the previously mentioned system for mutually joining the leaves.

The sleeve 3 is then linked with anchoring means 4 adapted to be driven into the marine floor. Such means, schematized in the figures by a simple harpoon 4, project from the opposite part with respect to the bundle 2 and they can have different structures and installation methods, which, considered as such, fall outside the scope of the present invention and are to be deemed known for similar uses. For example, the systems used might include expansion or screwing systems capable of providing an adequate stability of the anchorage, also depending on the characteristics of the floor which might generally be sandy or covered by a layer of dead wood material (mixture of rhizomes and roots forming the so-called "mats", that is the residue of the extinct natural seagrass). With particular reference to figure 2, according to the invention single elements such as the one described just above, are preferably associated in ordered groupings, by means of a base 5 which holds the various sleeves 3 together substantially at the end from which the anchoring means 4 project.

In practice, the base can be made up of a flat panel 5, typically with the main dimensions approximately about 100 cm by 50 cm, and being a few centimeters thick, in such a manner to provide a given flexibility for better adaptation to the laying conditions. The sleeves 3 raise perpendicularly from the upper face 5a of the panel 5, while the anchorage harpoons 4 project from the opposite

face intended to come into contact with the marine floor.

The joining between the sleeves 3 and the panel 5 can be obtained through the insertion of the former into respective holes 6 formed in the latter. For this reason, each of the sleeves may be provided, right at the lower end, with a radially projecting collar 3a, in such a manner to abut on the panel and stabilize its support thereon.

Also in this case, the fixing can be carried out through mechanical means, gluing or melting, depending on the requirements, bearing in mind that also the panel is preferably made of the same synthetic material used for the other components already mentioned. Apart from the holes 6 engaged by the sleeves 3, the panel 5 is advantageously provided with additional holes 7, whose purpose is to assist the settling of the sand transported by the wave motion, as well as the establishment of the aquatic animals (the so-called "infauna" comprising crustaceans, annelids, mollusks etc) which need to enter, by digging tunnels, into the marine floor.

A grouping like the one just described forms in turn a module which can be used, by way of serial repetition, to compose artificial Posidonia oceanica meadows of the extension desired and required by the circumstances. Such operation can be possibly facilitated thanks to reference or engagement systems (even simple matching grooves/protrusions) provided along the periphery of the panels 5. Clearly, the modules may be removed, even separately, for replacement upon possible wear out or damage.

The artificial meadows thus created are capable of forming an actual barrier against coastal erosion, serving

as an obstacle and a filter upon the action of the wave motion, reducing the impact force considerably. In particular, this result is obtained thanks to the presence of the sleeves 3 which, due to their relatively rigid characteristics, perform an efficient function of "breaking" the wave front and dissipating its energy, an action not provided for by the known art. The sleeves 3, and consequently the bundles 1 inside the modular grouping, instead of being aligned, may be arranged according to mutually offset arrays, in such a manner to further enhance the dispersion and filtering action.

It should be stressed that the leaves gathered in bundles, due to their closely packed mass, and although the bending, also contributes to counter the wave motion, both towards the shore and during the return offshore, following a movement similar to the one typical of natural leaves. As a matter of fact, during such return motion the bundles operate like a big comb withholding the sand particles taken away from the coast. Regarding this matter, it should be pointed out that the single module made according to the size indicated above can accommodate about three hundred bundles 1 (with an overall number of about two thousand leaves 2), which implies a considerably dense structure (roughly around six hundred bundles per square meter) , and a consequently huge dispersion and withholding capacity.

As mentioned, in order to realize the structure according to the invention, any material known and already used for similar purposes (see the documents mentioned in the introductory part) may be used, selected from the family of non-toxic and inert synthetic materials, which do not release any harmful substances such as additives

and pigments into the marine environment. For example, alongside polyethylene, also polyesters, polypropylene or other similar polymer materials may be used. These materials are available on the market and can be processed according technologies absolutely known per se.

Animal and plant organisms will establish quickly on the entire part of the module emerged from the sand (sleeves and leaves) as it usually occurs in the natural seagrass meadows. The leaves shall be covered, among others, with bryozoans, sedentary annelids, turf-forming and erect algae and hydrozoans. The large number of leaves will then restore the environmental conditions suitable for the deposition of eggs by mollusks, fish and other species of animals. In this manner, the conditions for a new development of the plant and animal species, which shall also spread to the neighboring areas generating a substantial enrichment of the marine biodiversity, shall be restored in the area of the sea affected by the extinction of natural seagrass meadows, and thus turned out completely uninhabitable.

As mentioned, the tubular sleeve which represents a particularly advantageous aspect of the invention can be cylindrical like in the example, or be of other shapes, for example prism-shaped. Furthermore, as shown in the variant embodiment of figures 3 and 4, radial outgrowths 8

- typically substantially thread-shaped and also tuft-like in such a manner to create a sort of artificial hairiness

- can be provided on the side surface of the sleeve. Projecting towards the external, such outgrowths further reduce the free volume between one bundle and the other, enhancing the dispersion force and the sand-withholding capacity of the structure. As a matter of fact, a solution

functionally equivalent to the tubular sleeve may comprise a solid axial stem portion (that is, extended along the axis of the bundle) from one of whose ends the first end of the bundle of leaves departs. Clearly, also the shape and the dimensions of the leaves can be subjected to modifications, just like the base 5, if present. In this latter case, the base can integrate means for anchoring onto the marine floor, such means being independent and/or arranged at different positions with respect to the position of the bundles of leaves .

The artificial aquatic plant structure according to the present invention may undergo other variants and/or modifications without for this reason departing from the protecting scope of the invention itself as defined by the attached claims.