DEVICE AND METHOD FOR COASTAL EROSION MITIGATION USING CONCRETE DOME STRUCTURES

Description

This application claims priority to U.S. Provisional Application No. 63/676,030, filed Jul. 26, 2025, the entirety of which is incorporated by reference.

FIELD OF INVENTION

This invention relates to devices and methods for the mitigation of erosion, along shorelines or banks of water bodies. More particularly, the invention discloses the use of specially-designed dome structures. These structures, inspired by the natural geometry of clam shells, are designed to be deployed in shallow-water environments to effectively reduce wave energy and facilitate sediment capture. The primary objective of this invention is to provide a sustainable and efficient solution to combat erosion of shorelines and banks to protect and preserve vulnerable ecosystems, reduce turbidity in bodies of water experiencing bank erosion such as rivers and lakes, and protect littoral property from destruction.

BACKGROUND OF THE INVENTION

Coastal erosion has long been recognized as a critical environmental, economic, and infrastructural challenge. Shorelines formed of unconsolidated silts, clays, and organic marsh deposits are especially vulnerable to wave-induced or ship-wake disruption, storm-surge overtopping, and anthropogenic alterations to littoral sediment budgets.

Inland bodies of water, while usually developing less-energetic significant-wave heights than ocean coasts, also suffer erosion caused by wind-driven waves and, especially, small-craft wakes.

Traditional physical countermeasures include vertical steel sheet-pile seawalls, concrete bulkheads, rubble-mound revetments, and rip-rap sills. On lakes and rivers, boaters are often required to (but do not always) reduce speed significantly to reduce wake energy and consequent erosion.

Although known structures can provide an immediate physical barrier, installation of such structures is capital-intensive, demands heavy equipment for installation, may exacerbate local scour through wave reflection, and may sever tidal exchange critical to wetlands health.

Straightforward and long-known approaches to mitigating erosion include collecting, transporting, and depositing heavy, bulky materials, often rock or broken concrete slabs, some distance from shorelines. Some proposed solutions often combine these known approaches in multiple-structure configurations to mitigate their distinct disadvantages that include cost, reduction of water exchange, and erosion of the control measures themselves.

For example, U.S. Pat. No. 5,741,086 to Bores (1998) discloses a harbor-calming system employing low-crown, overflowable rubble breakwaters in combination with permeable quays and channels to dissipate short-period gravity waves. The breakwaters and quays described by Bores are linear and continuous, hundreds of feet long, necessarily in multiple layers with different functions, and founded on prepared subsurface bedding. Construction therefore entails enormously cost- and labor-intensive earthworks, results in very large shoreline footprints, and significantly reduces water exchange between the in-shore environment and the water body.

U.S. Pat. No. 7,603,959 to Veazey (2009) teaches modular precast concrete box units—often hexagonal—that (among other uses) can interlock to create levees, sea walls or breakwaters. These modules are transported by truck, set with cranes, and grouted together. Because their external faces are planar, incident wave energy is largely reflected, which can enhance toe scour at their bases. More important, used as seawalls and levees, such structures are intended to entirely preclude water passage and therefore badly disrupt marine or littoral ecosystems. Finally, as with many known erosion-mitigation strategies, essentially all of the material and structure needed for construction and effectiveness of such structures must be fabricated and transported, resulting in very high cost.

Correcting this problem is one of the present invention's greatest advantages: a large majority of the mass employed to deflect and dissipate incident wave action need not be built and moved, but is collected and held in situ by the invention itself. The mass of the finished structure, after remaining in place for sufficient time, consists mostly of deposited sediment that lends great stability to the structure produced by the invention. The present invention consists essentially of one or more large domelike molds, which, like clamshells on a beach, gradually receive and “cast” deposited sediment into large domed structures that serve as barriers to effectively attenuate wave energy.

Because the subsurface bears the great weight of collected sediment, these domed structures accomplish wave reflection and dissipation over a large areal surface, much larger than would be achievable using traditional solid or broken-surface structures. Further, sediment is utilized for anchoring the domed structures without bearing the great weight created by other breakwater structures and avoids gradual subsidence of the domed structures into soft subsurface, a significant advantage over existing approaches.

Inspiration for utilizing dome structures in erosion control stems from their inherent geometric advantages. The dome is widely recognized for its strength, lightness, and efficiency in enclosing space. By leveraging these properties and adapting the dome into a clam-shell shape, the present invention discloses a structure capable of withstanding the dynamic forces of coastal waves. The clam-shell shape observed in natural marine environments exhibits remarkable stability and resistance to displacement, making it an ideal candidate for erosion-control applications.

Furthermore, a vent or hole is provided at the top of the domed structure of the invention, a critical feature that allows water and, more importantly, sediment to enter the structure. This vent or hole mechanism enhances the stability of the dome by increasing its weight and promotes sediment accumulation within the dome, further anchoring it to the seabed. Over time, the captured sediment contributes to the formation of a stable natural barrier against erosion, preserving the integrity of sandy soils and fostering the regeneration of marshland and other coastal habitats.

SUMMARY OF THE INVENTION

The present invention provides a solution for coastal erosion mitigation through the deployment of a plurality of dome structures. These domed structures are designed to harness the geometric strength of domes and their natural stability in shallow water, creating a robust and durable barrier against erosive forces. The primary structure of the invention is a dome-shaped structure created as a “quarter sphere”—i.e., for a sphere of radius r, a quarter sphere constitutes the outer portion remaining external to a cross-section made at r/2.

The dome is constructed, in the preferred embodiment, using high-strength concrete to leverage that material's low cost and ease of casting, and to withstand the harsh marine environment and resist degradation over time. The use of concrete ensures the structure's durability and resistance to environmental degradation, and compatibility with rebar reinforcement, while the quarter-sphere design optimizes its interaction with wave dynamics. Other materials are possible, such a cast polymer material, and lighter materials can further reduce cost of transportation and placement, though typically at the expense of greater cost of raw materials.

Other geometries are possible—for example, natural clamshells typically are not perfect hemispheres or quarter-spheres but instead have elliptical cross-sections. Such elliptical or other alternative geometries may display even greater wave attenuation, though their effectiveness at wave-energy dissipation must be balanced with the effectiveness of a given geometry at capturing and retaining ambient sediment. Because the devices are pre-cast in reusable molds, testing and adoption of geometries alternative to quarter-spheres requires only introduction of a new mold and re-orientation of supporting rebar radial and cross-members.

A vent hole located at the top of the dome allows water and sediment to enter the structure. This feature is critical for enhancing the dome's stability as the influx of sediment greatly increases the overall weight contained by the dome, thereby anchoring it more securely to the seabed. Additionally, the vent hole (which is sized to admit sediment-carrying water but to exclude marine animals, flora of significant size, and to avoid danger to humans or marine life) facilitates the natural accumulation of sediment, promoting the formation of an increasingly stable barrier over time.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top perspective view of one embodiment of the domed structure of the present invention.

FIG. 2 is a schematic centerline cross-section view of the domed structure of FIG. 1.

FIG. 3 is a schematic side view of the domed structure in place upon a water bottom.

FIG. 4 is a schematic top view of a plurality of domed structures as shown in FIG. 1 deployed along a shoreline.

FIG. 5 shows an outline of a sphere designating dashed quarter-spheres corresponding with the outer surface of the domed structure of FIG. 1.

FIG. 6 shows a schematic lateral top view of the domed structure of FIG. 1 having the quarter-sphere configuration depicted in FIG. 5.

DESCRIPTION OF THE EMBODIMENT

FIGS. 1 and 2 show one embodiment of the domed structure (10) of the present invention. Dome structure (10) is preferably comprised of reinforced concrete that is configured with a convex outer shell surface (12) and a concave inner shell surface (14) which form a domed wall or roof (18) and a circular base (20). Reinforcing (22) such as steel rebar or steel mesh will typically be utilized to reinforce the domed roof (18). A vent hole (15) is provided at the peak (17) of the dome structure (10) penetrating the outer shell surface (12) and the inner shell surface (14) through the shell (12). As previously discussed, quarter-spheres are one geometry available among many possibilities of concave dome structures, all of which are encompassed by the present invention

The roof (18) of the dome structure (10) preferably will be thinner at its upper portion and thicker at its base (20). This design approach ensures that the dome structure (10) is both lightweight and strong, facilitating ease of deployment while maintaining structural integrity. Generally, the dome structure (10) at its base (20) will be approximately twice as thick as at its peak (17) at vent hole (15). Other thickness ratios are possible and may be desirable depending on type of material used, size, number, and length of rebar used as reinforcing (22), the size and type of a wire mesh reinforcing, water depth at placement location, and other factors. The thickness gradient may take any form consistent with maintenance of structural stability. In all such embodiments, the heavier base (20) acts as an anchor, preventing the dome from being displaced by wave action while sediment accumulates within to eventually provide final stability.

For greater structural strength, the reinforcing (22) of the roof (18) of each dome structure (10) may be comprised of multiple lengths of rebar extending perpendicular to the base and meeting at the top vent hole. This rebar reinforcing (22) is generally spaced at equal intervals along the roof (18) of the dome structure (10) or as otherwise desired.

Where these lengths of rebar reinforcing (20) meet, they are joined together (by splicing, welding, or other similar means, depending on the type of rebar) to ensure the vent hole (15) is screened or subdivided into smaller openings (19). The openings (19) in the screened vent hole (15) will preferably be too small to permit the entrance of, for example, small children. Since the present apparatus may be placed alongside beaches to prevent or reverse their erosion, or along banks of rivers and lakes, swimmers and waders may encounter them. The rebar reinforcing (22) thus serves an essential safety purpose as well. Additional rebar reinforces the domes when placed hemispherically approximately halfway from base to top. All reinforcing rebar is preferably placed at the center of thickness of the concrete through which it runs. Preferably, reinforcing (22) is of the basalt type, principally for its greater resistance to corrosion in marine environments where the present invention is generally intended to be practiced.

FIG. 4 shows a plurality of domed structures (10) deployed in a water bottom (40) along a shoreline (45). Preferably the dome structures (10) will be deployed in shallow-water environments, typically to remain visible at the surface (44) as shown in FIG. 3, but submerged, at high tide. When sized appropriately and placed in lakes or rivers that do not experience appreciable tides, the dome structures (10) are preferably placed so that their top shells (12) are below surface height but remain visible, allowing sediment accumulation while retaining the ability to dissipate wave and wake energy. Offshore, inter-tidal placement as shown in FIG. 4 ensures that the dome structures (10) remain visible to avoid hazards to navigation while effectively mitigating wave energy from waves (50). Multiple dome structures (10) typically will be placed along a length of shoreline (45) for protection. These multiple dome structures (10) may be placed in a variety of patterns and in multiple layers.

The shape dome structures (10) effectively dissipate wave energy, reducing its impact on the shoreline or bank, without unduly eroding the structure itself. By redirecting and absorbing wave forces (50), the dome structures (10) protect the coastal areas behind them from erosion without suffering the same erosive effects as prior approaches that employ irregular rubble surfaces or planar faces. The superior energy dissipation of the dome structures (10) is both more effective and less destructive compared to earlier solutions. Finally, this energy dissipation by curved surfaces of the dome structures (10) also contributes to the stabilization of sediment collected around the domes as well as captured within them.

The vent hole (15) of the dome structures (10) not only enhances the stability of the dome structures (10) but also facilitates the capture of sediment. As waves flow over the dome structures (10), sediment is deposited within the inner shell surface (14) of the dome structures (10), gradually filling the concave inner space. This accumulation of sediment around and inside the dome structures (10) as shown in FIG. 3 provides support to the base (20) and increases the weight and stability of the dome structures (10), making them more effective in erosion control over time.

By mitigating coastal erosion and promoting sediment accumulation, the dome structures (10) foster the regeneration of marshland and other coastal habitats. This ecological restoration provides numerous benefits, including improved habitat for wildlife, enhanced water quality, and increased resilience against future erosion events. Placed to protect lake shores and riverbanks, the dome structures (10) reduce water turbidity by preventing shoreline erosion and prevent waterfront property from being washed away during flooding events.

The dome structures (10) are pre-cast and transported, typically by barge, to their placement location. Because the eventual wave-opposed mass of these devices is largely attributable to captured sediment, only a small portion of the eventual structure's mass must be transported and handled, greatly reducing cost.

These dome structures (10) also cause significantly less damage to transporting barges than the typical rock or concrete rubble used to construct breakwaters and jetties. These latter methods, for cost reasons, use largely waste materials that are not sanded or ground down and, because they must be managed in bulk and not by piece, interact very harshly with truck cargo boxes and barge decks. The dome structures (10) of the present invention, by contrast, can be efficiently and stably stacked and lifted on and off barge decks with minimal damage, reducing need for repair and re-painting of transport vehicles.

FIG. 5 shows the quarter-sphere geometry that is preferably utilized for the dome structures 10. As shown in FIG. 5, sphere (25) is comprised of upper and lower quarter-spheres (24) which may be utilized to created molds from which the domed structures (10) shown in FIG. 6 may be formed. Quarter-spheres are but one geometry available among many possibilities of concave dome structures, all of which are encompassed by the present invention.

The domed structure (10) and the method of manufacture and deployment presented herein and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and steps thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form described being merely an example embodiment of the invention.