Modular shell reef for erosion abatement

Abstract

The disclosed systems, methods, and apparatuses may combat coastal erosion using a shell module shaped to enable retention of sand on a beach and shore face. The shell module may be shaped to minimizing interference with recreational use of the beach and providing a beneficial environment for desirable sea life. The modular shell can be conveniently transported and emplaced in shell reefs. These shell reefs may comprise multiple, optionally interlocking shell modules. These shell reefs can prevent fill, such as sand, de-watered sand, or sand slurry from being scoured and sluiced out to sea. The disclosed systems and methods harness the energy of incoming and returning waves, including tidal and surf action, to assist in spreading the fill, recreating a natural beach, complete with layers of sand capable of resisting the scouring force of ocean waves and currents.

What is claimed is: 
     
         1 . A sand-retaining shell module adapted for placement near a shoreline, comprising:
 two footers ( 110 ) generally parallel to a longitudinal axis, each footer comprising outer face ( 111 ) and an inner face ( 113 ); and   a bridging member ( 120 ) that connects the two footers, wherein the bridging member has a convex upper surface ( 145 ) peaking at the longitudinal axis and extending downward on either side of the longitudinal axis to meet the outer face of each footer, and a concave undersurface ( 147 ) peaking at the longitudinal axis and extending downward on either side of the longitudinal axis to meet the inner face of each footer.   
     
     
         2 . The sand-retaining shell module of  claim 1 , wherein the shell module, when viewed from above, has a generally square or rectangular peripheral outline. 
     
     
         3 . The sand-retaining shell module of  claim 1 , wherein the shell module has a first end and a second end, each generally orthogonal to the longitudinal axis. 
     
     
         4 . The sand-retaining shell module of  claim 3 , wherein the first end is formed with a projection and the second end is formed with a complementary recess, enabling installation of adjacent shell modules in an interlocked configuration. 
     
     
         5 . The sand-retaining shell module of  claim 1 , wherein the bridging member is formed with a central portion aligned with the longitudinal axis and a perforated portion connecting the central portion and one of the two footers. 
     
     
         6 . The sand-retaining shell module of  claim 5 , wherein the perforated portion is formed with a plurality of slots extending from the upper surface to the undersurface of the bridging member, thereby facilitating passage of water and marine life through said module. 
     
     
         7 . The sand-retaining shell module of  claim 5 , wherein the bridging member reduces in thickness from at least one of the two footers to the central portion. 
     
     
         8 . The sand-retaining shell module of  claim 1 , wherein the shell module comprises a unitary structure made with a mold. 
     
     
         9 . A system for abating erosion of a shoreline, comprising:
 a main shell reef ( 310 ) emplaced along the shoreline at least partially within the shore face ( 403 ) and beyond the mean low water line ( 305 ), the shell reef comprising a plurality of adjacent shell modules ( 100 ); and   wherein each of the adjacent shell modules comprises:
 two footers ( 110 ) generally parallel to a longitudinal axis ( 101 ), each footer comprising an outer face ( 111 ), and 
 a bridging member ( 120 ) connecting the footers, wherein the bridging member has a convex upper surface ( 145 ) peaking at the longitudinal axis and extending downward on either side of the longitudinal axis to meet the outer face of each footer. 
   
     
     
         10 . The system of  claim 9 , wherein a top of the main shell reef is below the mean low water level. 
     
     
         11 . The system of  claim 9 , wherein each footer comprises an inner face, and wherein the bridging member has a concave undersurface peaking at the longitudinal axis and extending downward on either side of the longitudinal axis to meet the inner face of each footer. 
     
     
         12 . The system of  claim 9 , wherein the adjacent shell modules are formed with projections and recesses that interlock the adjacent shell modules to form the main shell reef. 
     
     
         13 . The system of  claim 8 , wherein the shell modules are placed to embed the footers of each shell module into the shore face. 
     
     
         14 . The system of  claim 9 , further comprising one or more additional shell reefs emplaced between the main shell reef and the mean low water line, the one or more additional shell reefs angled towards the shoreline, the one or more additional shell reefs submerged below the mean low water level. 
     
     
         15 . The system of  claim 14 , wherein each of the one or more additional shell reefs contacts the main shell reef. 
     
     
         16 . A method for abating erosion of a shoreline comprising:
 emplacing a main shell reef ( 310 ) with a convex upper surface along a shoreline at least partially within a shore face ( 403 ) and beyond the mean low water line ( 305 ), a top of the main shell reef below the mean low water level ( 409 ); and   depositing fill ( 410 ) at a location within the surf zone ( 405 ) between the main shell reef and the toe ( 301 ).   
     
     
         17 . The method of  claim 16 , further comprising emplacing an additional shell reef between the main shell reef and the mean low water line, the additional shell reef angled towards the shoreline, and wherein the location is up-drift of the additional shell reef. 
     
     
         18 . The method of  claim 16 , wherein the additional shell reef connects with the main shell reef. 
     
     
         19 . The method of  claim 16 , wherein the fill comprises at least one of sand, sand slurry, and dewatered sand slurry. 
     
     
         20 . The method of  claim 16 , wherein the main shell reef comprises a plurality of adjacent shell modules formed with projections and recesses that interlock the adjacent shell modules to form the main shell reef. 
     
     
         21 . The method of  claim 16 , wherein the main shell reef comprises a plurality of adjacent shell modules, each shell module formed with two footers parallel to a longitudinal axis of the shell module, and wherein emplacing the main shell reef comprises embedding the footers of each shell module into the shore face.