Figure 33 - uploaded by Ernest R Smith
Content may be subject to copyright.
Source publication
Context in source publication
Similar publications
Citations
... The relatively severe beach erosion south of Ocean City has been noticed for at least 100 years, long before constructing the jetties. After the construction of jetties at the Ocean City Inlet in 1930s, the severity increased because the jetties block the southward sediment transport, at least for many years before the by-pass system was implemented (SMITH, 1988). ...
In an effort to assess the possible changes to physical oceanographic processes that might result from alteration of bathymetry as a result of dredging or sand mining, we evaluated the differences in the output of various numerical models run with the natural and hypothetical post-dredging bottom conditions. Fenwick and Isle of Wight Shoals offshore of the Delaware-Maryland border of the mid-Atlantic continental shelf served as the test site. We considered two dredging scenarios, a one-time removal of 2 × 106 m3 of sand from each of two shoals and a cumulative removal of 24.4 × 106 m3, but only the larger appeared significant. The study of wave transformation processes relied upon a series of runs of the REF/DIF-1 model using sixty wave conditions selected from analysis of the records from a nearby, offshore wave gauge. The model was tuned and calibrated by comparing measured near-shore wave conditions with data calculated using the same measured offshore waves that generated the real near-shore conditions. The modeled, post-dredging data indicated an increase in wave height of up to a factor of two in the area between the dredged shoals and the shore and, in some locations, a lesser increase in breaking wave height and a decrease in breaking wave height modulation. The model results also may help explain the existing pattern of erosion and relative stability. Application of the well-known SLOSH model (Sea, Lake, and Overland Surges from Hurricanes) for storm surge and POM (Princeton Ocean Model) for tidal currents indicates that the likely dredging related changes in those processes are negligible.
... There is a long history of inlet stabilization (Smith, 1988), but unfortunately this activity was usually accomplished with little or no knowledge of the consequences for downdrift beaches (Inman andNordstrom, 1978 andBruun, 1986). While the morphology of tidal inlets is well defined, the spatial extent and temporal behavior of inlet-induced beach erosion was not delineated on a systematic basis (Bruun, 1996 andMehta, 1996). ...
... The inlet was reopened and permanently stabilized by the U.S. Army Corps of Engineers in 1953. The inlet was stabilized with two 432-meter long jetties to maintain a 241-meter wide channel (Smith, 1988). The net littoral transport is to the west, and the sediment volume has been estimated to be 161,300 m 3 /yr (Leatherman and Allen, 1986). ...
Stabilized tidal inlets have caused severe downdrift erosion that threatens structures and barrier island stability. This problem has long been established, but the full impact has often been misinterpreted, as most researches have not recognized the "s" signature of this mode of shoreline behavior. Furthermore, damaging erosion along beaches in front of coastal communities has sometimes been attributed to tidal inlets because simple sediment budget models have been used (incorrectly) to quantify the problem. A comparison of six inlets along the U.S. Northeast coast demonstrates a consistent pattern of change: the arc of erosion is a mobile planform feature, its spatial behavior is time dependent, it expands downdrift at a non-linear rate, and the area of change consistently manifests an "s" pattern. Long-term (100+ year) shoreline change data were used to identify these relationships and quantify the impact of tidal inlets on downdrift beaches. This paper will focus on Moriches Inlet along the southern shore of Long Island, New York.
... These bulkheads were extended in 1963 due, again, to continued erosion of the inlet banks adjacent to the existing jetties/ bulkheads. Periodically, rubble material has been placed on the jetties to repair storm damage (Smith 1988). ...
... It paralleled the north jetty for about 750 ft from the landward end seaward, then angled toward the north jetty, constricting the inlet from 1,100 to 600 ft wide. The last 530 ft of the south jetty again paralleled the north jetty (Smith 1988). ...
This study examines the scattering of obliquely incident waves by a submerged pile–rock breakwater, which consists of two rows of closely spaced piles and a rock core between them. Based on linear potential theory, a closed-form analytical solution for the present problem is developed using matched eigenfunction expansions. The analytical solution is novel because of the new submerged pile–rock-type breakwater. The analytical solution is confirmed by an independently developed multi-domain boundary element method solution. The analytical solution is also compared with experimental data for three special cases of the present breakwater. Numerical examples are presented to investigate the effects of structural parameters and wave parameters on the reflection, transmission and energy loss coefficients of the breakwater. It is found that the wave energy dissipation by the submerged pile–rock breakwater is mainly contributed by the rock core, and only a small part of wave energy dissipation is due to the closely spaced piles.
The world's coastal zones are experiencing rapid development and an increase in storms and flooding. These hazards put coastal communities at heightened risk, which may increase with habitat loss. Here we analyse globally the role and cost effectiveness of coral reefs in risk reduction. Meta-analyses reveal that coral reefs provide substantial protection against natural hazards by reducing wave energy by an average of 97%. Reef crests alone dissipate most of this energy (86%). There are 100 million or more people who may receive risk reduction benefits from reefs or bear hazard mitigation and adaptation costs if reefs are degraded. We show that coral reefs can provide comparable wave attenuation benefits to artificial defences such as breakwaters, and reef defences can be enhanced cost effectively. Reefs face growing threats yet there is opportunity to guide adaptation and hazard mitigation investments towards reef restoration to strengthen this first line of coastal defence.
Increasing human populations along marine coastlines has lead to increasing urbanization of the marine environment. Despite
decades of investigations on terrestrial ecosystems, the effect of urbanization on marine life is not well understood. Riprap
is the rocky rubble used to build jetties, breakwaters, and armored shorelines. Roughly 30% of the southern California shoreline
supports some form of riprap, while 29% of the shoreline is natural rocky substrate. Astonishingly few studies have investigated
this anthropogenic rocky habitat even though it rivals a natural habitat in area on a regional scale along a coastline that
has been extensively studied. In this study, I compared the diversity and community structure of exposed rocky intertidal
communities on four riprap and four natural sites in southern California. I ask the following questions: (1) does diversity
or community composition differ between intertidal communities on riprap and natural rocky habitats in southern California,
(2) if so, which organisms contribute to those differences, (3) which physical factors are contributing to these differences,
and (4) do riprap habitats support higher abundances of invasive species than natural habitats? On average, riprap and natural
rocky habitats in wave exposed environments in southern California did not differ from each other in diversity or community
composition when considering the entire assemblage. However, when only mobile species were considered, they occurred in greater
diversity on natural shores. These differences appear to be driven by wave exposure. The presence of invasive species was
negligible in both natural and riprap habitats.
