Coastal Sediments '07

This paper discusses the simulation of nearshore bar migration using the CROSMOR profile model. Two sediment transport formulations have been used : the method of Van Rijn and that of Van der Werf. The model has been applied to two large-scale laboratory experiments in the Delta flume of Delft Hydraulics. Both transport models can represent the trends observed in the laboratory experiments.

The present paper presents a rational expression for the initiation of motion for non-cohesive sediment under rough turbulent wave conditions. Previously proposed relationships for the initiation of motion are examined as well as laboratory measurements corresponding to fully rough turbulent boundary layers (which is normally the case under prototype conditions). By combining the modified Shields criterion as proposed by Bagnold with the wave friction factor, f_w, from Jonsson, an easily applied criterion for the threshold velocity for incipient motion under rough turbulent conditions. The new relationship is formulated as U_w,cr = 4φ_cr[1.1 log₁₀φ_cr T/(πd₅₀))–0.08]^1/0.9. Predictions with the new criterion are shown to be in good agreement with measurements over the full range of typically encountered engineering conditions.

During the 2005 CROSSTEX laboratory experiments, a series of bar generation and degeneration events and repeated cycles of offshore and onshore transport were documented. These changes were driven by regular modifications to the specified incident wave field. Based on collected bathymetric data we first assessed the spatial and temporal movement of two sand bars. We used hydrodynamic and video data to relate the movement of these bars to the occurrence of wave breaking and the magnitudes of undertow, velocity skewness and acceleration skewness. This analysis indicates that undertow currents generated the first sand bar through offshore-directed transport. The second bar was formed by onshore transport, with the first bar serving as the likely sediment source. On the other hand, onshore migration and degeneration of both sand bars correlated well with acceleration skewness.

A new practical model for net sand transport induced by non-breaking waves and currents is being developed within the SANTOSS research project. Phase I of model development is reported here. In comparison with existing models, the main improvement is the description of the wave-related transport. More specifically, phase lag effects in the sheet-flow and ripple regime — which potentially have a large effect on the net transport — are accounted for in a parameterized way. The santoss model is calibrated against a large set of data from oscillatory flow tunnel experiments covering a wide range of flow and sand conditions. The new model is seen to perform better than existing practical transport models, and is applicable to a larger range of conditions.

A total load sediment transport formula based on recent studies on the bed load and suspended load transport for the nearshore is presented. Phase-lag in the sheet-flow layer or due to ripples, as well as acceleration effects, is included in the formula. A sensitivity analysis is performed to better qualify and quantify the current-related and wave-related sediment transport. It appeared that the prediction of the ripple characteristics is fundamental for a proper estimation of the suspended load in the direction of the waves. For the longshore sediment transport where the current-related total load prevails, the formulas are not as sensitive to ripples.

Small-scale laboratory experiments were conducted to investigate the total and the cross-shore distribution of longshore sand transport rate on long straight beaches of uniform grain size under monochromatic waves. An efficient trap system was introduced to collect the sediments transported alongshore. Substantial peak in the distribution of longshore sand transport rate was observed in the swash zone, in addition to the peak at the breaker zone under, relatively strong plunging breakers. The cross-shore distribution of longshore sand transport rate was found to be dependent on the profile of the beach and the period of the waves, which controlled the breaker type.

The horizontal pressure gradient associated with the steep front of forward-leaning breaking waves is transmitted into the porous bottom to depths far exceeding the depth of the shear-stress-induced surficial transport sheet flow layer. The horizontal pressure gradient induces a flow within the bed which exerts a seepage force on the soil-skeleton. If sufficiently large the seepage force will cause a failure of the soil matrix and displace subsurface sediment grains, i.e. result in a subsurface sediment transport. This paper investigates the pressure-induced subsurface transport mechanism experimentally by photographically recording the displacement profile of subsurface lightweight sediment grains during passage of the steep front of breaking waves. A simple theoretical model for the dynamic response of subsurface sediments in failure is developed and provides predicted displacement profiles in reasonable agreement with measurements. The potential importance of the subsurface sediment transport mechanism is discussed.

Predictive skills to track the discharged sand grains are essential to design optimum sand-recycling system. This paper develops a new numerical model which focuses on the movement of a group of sand grains discharged at arbitrary locations in the near-shore area. While particles in a group of discharged sands may be transported with the group, spatial distribution of the group may be dispersed due to certain random effects such as near-bottom turbulence and wave motions. The present model follows the concept of existing process-based bedload sediment transport model to represent the former "mean" movement of sand particles. In addition, the model introduces random walk theory to account for the latter dispersive characteristics of discharged sand grains. The model shows excellent predictive skills of both mean and dispersive movement of dyed sand grains observed in the newly performed field survey.

Suspended sediment transport dynamics occurring at relatively short time scales under super-critical wave groups created by moving high speed vessels are investigated by means of field measurements and the application of numerical models. Examples are provided from a variety of different environments, including predominately sandy beaches in low energy estuarine and fluvial settings. Model simulations combining the hydrodynamics of the wakes with steady currents and a sand transport model provide results that are largely consistent with field measurements and observations of the suspended load fraction. Wakes re-suspend sand in the nearshore that would otherwise be immobile and move it incrementally offshore and alongshore, eventually into deeper water where stronger ambient flows (tidal or fluvial) can transport the sediment. Super-critical wakes from high speed vessels have a tendency to cause offshore transport of sand-sized sediment leading to beach flattening while their sub-critical counterparts often lead to beach steepening.

X-Ray computed tomography (CAT scanning) has enabled the measurement of the relative density of sand ripples inside the sediment column during ripple migration. A sand ripple produced by stationary flow inside a vertical water tunnel reveals different internal density stratification on CAT-scan profiles. CAT-scan measurements provide a very precise integrated measurement of sediment transport inside the sand ripple, both at the water-sediment interface and in the water column. Results give the total sediment transport (suspended load column concentration and bed load) and illustrate the contribution of each type of sediment transport and their relative magnitude along sand ripples.

The potential relevance of wave skewness and sloping beds on morphodynamic predictions is investigated. Based on a comparison with measurements it was shown that the phase lag is potentially important for modeling nearshore bar dynamics as it influences the suspended wave related transports (magnitude and direction). Velocity skewness results in a phase shift between the orbital motion and the instantaneous bed shear stress increasing onshore bed load transport. It was seen that its influence is relatively small but does affect bar migration and helps to predict the observed asymmetric bar shape. The bed slope affecting the initiation of motion and sediment bed-load transport magnitude and direction are investigated by comparing scour hole predictions. The initiation of motion, which is also included on the suspended transports, only has an effect for somewhat steeper slopes. The modifications of bed-load direction and magnitude significantly affect the horizontal and vertical scour hole equilibrium dimensions.

The highly active Atlantic Ocean hurricane seasons of 2004 and 2005 produced unique morphological changes outside of the surf zone. This paper focuses on two northeast Florida areas — St. Johns County and Volusia County. These morphological changes, as determined by bathymetric surveys, revealed net sediment accretion in greater than 30-foot water depths after the 2004 storms just offshore of the St. Johns County Shore Protection Project and net sediment erosion on sand shoals located in 60-foot water depths, about seven miles offshore of Volusia County after the 2005 storms. Analyses of beach profiles and borrow area survey data revealed significant sediment transport at large depths, greater than those associated with typical wave conditions. Application of depth of closure and near bottom velocity methods showed wave conditions in 2004 and 2005 capable of sediment transport at these large depths.

Some 24 different indicators of the net littoral or alongshore drift are identified. Most of these relate to the geomorphic and sedimentologic properties of the littoral system, but also include deductions from wind data and wave properties. Not all indicators can be accorded equal confidence as definitive indicators.

The cross-shore variation of long-term average longshore sediment transport rate was examined on the basis of longshore sediment transport rates at the Hasaki coast in Japan for 15 years estimated using a one-dimensional numerical model of longshore current velocity. The model was calibrated with longshore current velocities measured once a day at about 50-m intervals along a 427-meter-long pier at the study site for the same period. Numerical simulations showed that the average longshore sediment transport rate was northward near the shore, but southward away from the shore, where the seaward distance from the shore is larger than 150 m.

Based on longshore sand transport experiments performed in a large basin, measured sand transport rates obtained for spilling and plunging waves are compared to the Bodge and Dean and Watanabe distributed load formulas, representative of typical formulas applied in engineering practice. Neither formula estimates the measurements satisfactorily. The Bodge and Dean formula is sensitive to changes in energy flux and does not include threshold shear. The Watanabe formula includes critical shear, but transport estimates are made from time-averaged values of bottom shear stress, which did not exceed critical shear stress at most cross-shore locations. A new transport formula is introduced based on time-dependent shear stress calculated from the total velocity that includes the wave orbital velocity. The new formula gives reasonable estimates for both spilling and plunging breaker types. A conclusion is that it is essential to represent the time-dependent, or fluctuating, component of fluid motion in predictive equations of the longshore sand transport rate.

Reservoirs, dams and barrages regulating the discharges of the Danube river, cut-offs of meanders and the jetties at Sulina mouth have disrupted the natural discharge and circulation of sediment on the coastal zone of Danube Delta. The aim of our research is to quantify the alongshore sediment transport and use this as a prime input to construct a sediment budget. Based on regional wind (1991 – 2000) data and a nearshore state-of-the-art wave model a morphologically representative wave climate along the representative depth contours of the Danube Delta was determined. This forms the basic input for a one-line model approach deriving the alongshore sediment transport and resulting coastline changes. The closure depth was computed and used, along with alongshore sediment transport gradients, to obtain the sediment budget.

Measurements of suspended sediment concentration profiles, C-Profiles, and hydrodynamic conditions were obtained in the surf zone on a barred beach composed of fine sand using streamer traps. A simple model was used to estimate the total longshore sediment flux. C-Profiles predicted for wave-current conditions were found to compare favorably with the field data. In some cases the cross-shore distribution of LST exhibited two peaks associated with wave shoaling and breaking over the bars. Comparisons between present results and predictions from well-known longshore transport formula and a formulae for sediment transport in combined wave-current conditions generally show good agreement. The results indicates that sediment transport processes in the surf zone are not markedly different from those operating in unidirectional and combined wave-current flows under non-breaking wave conditions. The work contributes to the body of published field data by documenting the rates and cross-shore distribution of LST at a previously unstudied field site.

Experiments were carried out in a flume 36 m long and 55 cm wide equipped with a piston wave generator. The sloping bottom consists of a loose material of low density (1.19 kg L^–1) with a median diameter d₅₀=0.6 mm in order that Shields and Rouse numbers are of the same magnitude as those of natural environments. Irregular waves are generated according to a JONSWAP spectrum. The waves are measured along the flume and bottom profiles are recorded in between repeated wave sequences. The infragravity modes amplitudes along the flumeare obtained for different wave climates. The correlation between the incident short wave envelope and the infragravity waves clearly indicates that the latter is the consequence of both a break point and a bound long wave release mechanisms.

The paper describes large-scale laboratory experiments performed with simultaneous measurements of suspended sand concentrations, free surface elevations and three-component velocities (including turbulent fluctuations) at several levels above the sea bed. The data from these experiments are used to develop a more correct description of the contribution of vertical velocity to the convective sand flux and the relationships between fluctuations of turbulent kinetic energy and wave energy dissipation for the estimation of local sand suspending and advection to the temporal variation of suspended sediment concentration.

A contour-line-change model considering the sorting effect of grain size was applied to the prediction of the changes in longitudinal profile of a model beach composed of sand of mixed grain size. The results were compared with the experimental results using a large wave tank. The experimental results that sand of mixed grain size is sorted into fine and coarse sand, and that coarse sand is transported shoreward, forming a berm, whereas fine sand sinks into a zone deeper than the depth of closure h_c were accurately reproduced by the numerical simulation. Furthermore, the result that the formation of the berm is rapid, whereas seabed changes in the offshore zone are slow, was also reproduced by the numerical model. The results of the calculation of changes in the content rate indicated that an increase in the volume of coarse sand contributes to the shoreline advance as a result of berm formation, whereas an increase in the volume of fine sand accelerates the outflow of fine sand into a zone deeper than h_c.

A probabilistic-deterministic model for swash zone sediment transport is presented and applied to predict cross-shore beach profile change under random waves. For accretionary conditions, inclusion of a random wave approach is essential for accurate representation of berm building processes. The model provides good estimates of beach volume changes for small scale laboratory experiments and sediment overwash volumes on a natural beach. Future modeling improvements are discussed, notably the inclusion of pre-suspended sediment, sediment pickup and long wave influences. Field and laboratory data show that sediment is advected into the swash zone from much further offshore than predicted by the classical swash solution, which increases uprush suspended sediment flux. Conversely, backwash suspended sediment flux may be limited by hindered pickup which may occur when the thickness of the backwash sheet flow layer becomes large relative to the flow depth.

Existing simple, practical models used to predict the transport rate of cohesionless sediment in the sheet flow regime have obvious shortcomings. They generally relate the transport rate directly to the velocity just outside the boundary layer or to an estimate of the instantaneous bed shear stress. Such models neglect important unsteady flow effects such as phase lags between the flow forcing and the bed shear stress and between the bed shear stress and the transport rate. Most also fail to account for the influence of the acceleration time history on the magnitude of the bed shear stress. In this paper a new simple, practical model is developed that aims to provide similar prediction accuracy as more complex process-based models without the computational expense. Convolution integrals are employed to obtain solutions for the governing differential equations in the time domain while accounting for the important unsteady flow effects.

A new middle-long term beach evolution model is proposed. This model is based on an analytically integrated sediment conservation equation (without assuming any hypothesis regarding the beach profile) and on a beach profile evolution model. The sediment conservation equation provides the long-shore sediment contributions and the beach profile evolution model combines the cross-shore sediment redistribution associated to seasonal process with this long-shore supplies. The model achieves the prediction of the shoreline position and the profile shape along a beach, from middle to long term scale. Furthermore, in this beach profile evolution model, the definition of the complete profile is incorporated (breaking zone, transition zone, exterior zone and geological zone). The proposed middle-long term beach evolution model has been applied in some test cases and it has also been compared to similar models showing a good capability to predict beach evolution in plan form and profile.

Returning to the starting point of Bagnold's basic study, sand transport equations were derived. A model for predicting beach changes by applying the concept of the equilibrium slope introduced by Inman and Bagnold and the energetics approach of Bagnold was developed. As a result, the physical rationality of the predictive model was enhanced compared with the original model. Typical beach changes caused by the obstruction of longshore sand transport and associated changes in grain size could be predicted. This becomes a practical tool for predicting three-dimensional beach changes on coasts composed of sand of mixed grain size.

Analytical models predict the growth (instability) of shoreline salients when deep-water waves approach the coast from highly oblique angles, contrary to classical shoreline change models in which shoreline salients can only dissipate. Using the process-based wave, circulation, and sediment transport model Delft3D, we test this prediction for simulated bathymetric and wave characteristics approximating the open-ocean conditions at Duck, North Carolina. We consider two cases: a uniform coast with a varying wave approach angle, and a bathymetry with coastal salients and a single high-angle boundary wave condition. Incident wave conditions include a swell case with no wind and a wind-wave case with active local wave regeneration by wind. The uniform-coast tests predict transport maxima at oblique wave angles for both wave cases, indicating the potential for shoreline instabilities, similar to the analytical models. However, the critical angle for instability is much higher in the wind-wave case. Our tests with coastal salients agree with previous findings that a minimum salient length scale may be required for the instability effect to be active. Here, a salient with a longshore scale of 4 km results in transport divergence (erosion; no instability) at the salient crest while an 8 km salient results in transport convergence (accretion; instability) at the crest.

We present a simple numerical model capable of producing distinctive scalloped bays of a form found when a sandy coastline extends downdrift of a rocky headland. The shape of such bays can often be approximated by a log-spiral—a curve for which the radius of curvature increases logarithmically with distance from the headland or ‘pinning point.' A considerable body of work has been published attributing this shape to the pattern of refraction and/or diffraction created as waves approaching from a dominant direction interact with the pinning point. Here, we present a fundamentally different explanation for these shapes. We use an existing one-line numerical model of wave-driven alongshore transport which includes shoaling and refraction over contours assumed to parallel local shoreline orientations. Rather than assuming a single wave angle, it generates new waves repeatedly according to an input wave climate. It does not include refraction or diffraction around the pinning point; thus, the log-spiral-like shape evolves as simply as a result of alongshore transport driven by a distribution of deep-water wave approach angles.

We investigate spit formation and evolution in light of the high-wave-angle instability in shoreline shape arising from a maximizing angle for wave-driven alongshore sediment transport. Single spits emerge in a simple one-contour line numerical model that evolves the coast using morphodynamic feedbacks and a ‘climate' of waves approaching the shore from variable directions. Analysis of sediment transport and shoreline stability metrics illustrate how spits can be generated, demonstrating how waves from all angles can play a role in spit formation and evolution. Simulations suggest that regardless of whether high- or low-angle waves dominate relative to the general shoreline trend, as spits extend offshore, they tend to orient themselves such that most of their coast barely experiences low-angle waves and alongshore sediment transport to the spit end is maximized. This ‘graded' spit shape minimizes gradients in sediment flux, while the recurve at the spit end experiences larger gradients and a region of high-angle instability. Examining hindcast wave data, similar trends are seen along the natural example of Long Point, Lake Erie, Canada.

Using National Ocean Service topographic sheets and global positioning system shoreline position surveys, historical shoreline changes of Parramore Island, Virginia, are quantified between 1852 and 2006 to address long- and short-term trends in shoreline movement. Quantitative analyses of twelve high water line (shoreline) positions indicate the shoreline is retreating at increasing rates in the short term (decadal) when compared with long-term trends (centennial). In particular, the behavior of the outer shoreline changed from clockwise rotational instability to sustained retreat. Parramore's entire, outer shoreline (Cells 3, 4, and 5) experienced a retreat rate of –3.6 m/yr over the long term (1852–2006) and –8.8 m/yr over the short term (1998–2006). The short-term rate changes indicate that the processes controlling shoreline trends, e.g., overwash to the south and inlet dynamics to the north, have intensified and/or changed relative to the long-term.

Weekly beach profiles, shoreline surveys, and nearshore wave measurements were collected before, during, and immediately after construction of the 1100-m Upham Beach nourishment project on the low-energy, west coast of Florida. Substantial planform diffusion occurred prior to construction completion via formation of a spit extending from the widest portion of the fill. Longshore spreading occurred abruptly, as opposed to gradual adjustment predicted by long-term models. Profile equilibration also occurred rapidly due to the passage of three hurricanes. Nine days after nourishment, Hurricane Frances generated high wave conditions (H_sig = 1.7 m) for this region, reducing the steep post-nourishment beach slope from 0.078 to 0.036, nearly the equilibrium slope (0.034). Hurricanes Ivan and Jeanne, which were nearly as energetic, resulted in much less slope change. This study indicated that profile equilibration was an event-driven process, contradicting the concept of long-term equilibration.

This paper summarizes the main findings from the investigations that were conducted, including GIS comparison of historic air photos, an 18-year wave hindcast, longshore sediment transport calculations, and extensive 2DH numerical modeling of hydrodynamics and sediment transport at Grand Marais Harbor. A sediment budget is presented based on geomorphic assessment and numerical modeling results. Future shoreline positions are also predicted.

A temporary construction harbour was built for the Egyptian Liquified Natural Gas (ELNG) facility in Abu Qir Bay on Egypt's Mediterranean Sea coast, west of the Rosetta Nile. A shoreline impact assessment was undertaken during the planning process which involved modelling the existing beach processes as well as shoreline development during construction, operation, decommissioning and recovery. Based on this assessment and modelling, a schedule of shoreline management and monitoring was proposed to ensure that the temporary harbour did not have a negative impact on the shoreline over its three year life. ELNG followed the proposed programme under scrutiny from the Egyptian Shoreline Protection Agency (SPA) and successfully restored the beach to its pre-construction state. This paper discusses the ELNG project, beach modelling, monitoring and the management programme as a case study, and assesses the beach modelling against the unique field data set.

Beach fills come in two forms, the most common being the nourishment, of a beach with sand to improve its recreational use and to enhance its capacity to buffer backshore properties from wave attack. The other form is a cobble berm (dynamic revetment), similarly used to protect shorefront properties, involving the construction of a cobble beach ridge. Both tend to be acceptable as shore-protection strategies due to their having natural forms found on coasts, acceptable where seawalls and conventional stone revetments are unacceptable. The design of beach fills should include considerations of the characteristics of their natural counterparts, so they have the visual aesthetics of natural beaches and respond to ocean processes during storms in much the same manner, increasing the probability that the fill will be stable in forming a permanent beach and in providing the desired level of protection for backshore properties.

Over the last two decades, a model of coastal gravel barrier evolution dependent on paraglacial reworking of limited, point-sourced glacigenic deposition has been proposed based on the Holocene evolution of the Nova Scotia Atlantic shoreline. Essential controls in this sequence were dependent on relative sea-level rise rate, sediment supply, basement structure and wave climate. Key in this sequence was the move from drift-aligned to swash-aligned barriers as a one-way process, with an emphasis that such swash alignment induced relative stability of barrier in the face of wave climate variability. Contemporary evidence from Nova Scotia following an extreme event and inferred environmental reconstruction of the gravel dominated barriers of southern England, suggest that swash-alignment is not as stable as hitherto identified, and that reversals from swash to drift-alignment and quick breakdown by extreme storm need to be considered as part of the potential sequence of gravel barrier evolution.

In response to the erosion of Cape Lookout State Park on the Oregon coast, a cobble berm (dynamic revetment) was constructed for shore protection, designed to be similar to a natural cobble beach. For added protection it is backed by an artificial dune reinforced with a core of sand-filled geotextile bags. We have monitored these structures since 2001, including periodic surveys and measurements of cobble mobility through particle tagging. The surveys have demonstrated profile responses to storms that are the same as found for natural cobble beaches, while the particle tagging has documented a high degree of cobble mobility, including a significant net longshore transport. To date the structures have survived five winters, including several major storms that have resulted in periodic overtopping, providing the desired level of protection to the park. However, due to the loss of cobbles from the cobble berm, its long-term stability is uncertain.

Mixed sediment beaches are morphologically distinct from and more complex than either sand or gravel only beaches. Three digital imaging techniques are employed to quantify surficial grain size and bedload sediment transport rates along the mixed sediment beaches of Kachemak Bay, Alaska. Applying digital imaging procedures originally developed for quickly and efficiently quantifying grain sizes of sand to coarse sediment classes gives promising results. Hundreds of grain size estimates lead to a quantitative characterization of the region's sediment at a significant reduction in cost and time as compared to traditional techniques. Both the sand and coarse fractions on this megatidal beach mobilize into self-organized bedforms that migrate alongshore with a seasonally reflecting the temporal pattern of the alongshore component of wave power. In contrast, the gravel bedforms also migrate in the cross-shore without significant seasonally suggesting that swash asymmetry is sufficient to mobilize the gravel even during low energy summer conditions.

A mixed sand and gravel beach 1,100 feet (335 m) in length was designed and constructed during 2005–2006 in Puget Sound as beach restoration, and is being monitored for changes in sediment distribution and profile shape. The beach is to function as improved habitat specifically for salmon, provide public access to the shoreline, and to control erosion of backshore fill. The beach was designed to mimic to the extent feasible the beach face slopes, elevations, and materials of a natural Puget Sound shoreline. Design beach dimensions and morphology were patterned after those of beaches documented at other Puget Sound locations. Forebeach material size gradation was designed from published relationships and judgment based on measured gradations at beaches having similar wave exposure and habitat as targeted for the project site. Construction monitoring assured the intent of the design was implemented. Post-construction monitoring has shown that the constructed beach is performing as designed.

The morphodynamic response of a mixed gravel and sand barrier is considered, by reference to storm conditions of varying magnitude, and under differing management regimes. Observations focus on evolution of the barrier at the temporal scale of the storm event, but the response during these episodic events is placed in context with potential impacts on longer term decadal scale geomorphological evolution. Decadal scale evolutionary trends indicate that the total volume of the barrier is declining and that the frequency of overwashing events and rate of rollback of the barrier is likely to increase. Changing profile and sediment sorting responses are evident during the interim phase, immediately following changes in management practice. Modifications to management practice present new issues that may include the possibility of fragmentation on the barrier.

This paper reports on laboratory experiments carried out on fine and coarse sand beaches under raised and lowered back beach groundwater levels. Onshore sediment transport was enhanced when the groundwater level was lowered under both accretionary and erosive conditions, whereas higher groundwater level promoted offshore sediment transport. Under swell conditions, the coarse beach showed accretion at all groundwater levels. In contrast, on the fine sand beach, lowering the groundwater level was able to induce accretion on a previously erosive profile. The groundwater level had less effect on beach profile evolution under storm conditions, suggesting that artificially lowering groundwater levels would not help much in the control of storm erosion, but could promote post-storm accretion on permeable beaches. Agreement between measured and modelled head levels was better on the coarse beach than on the fine beach, and better in the swash zone and within the beach than in the surf zone.

This paper examines the performance of a mixed sand-gravel beach in comparison with that of a pure gravel beach through a series of controlled laboratory experiments. The gravel beach was modelled using anthracite of a uniform (single) grain size while the mixed sand-gravel beach modelled by means of graded anthracite of the same median sediment size (D₅₀). The two model beaches were tested under identical wave conditions and beach profile changes were recorded. Significant differences were observed in the performance of the two beaches. The reduced permeability of the mixed sand-gravel beach seems to have the effect of reducing the onshore transport but increasing the offshore transport.

Data on the transport of material on mixed sand and shingle beaches using newly designed synthetic pebbles has been. collected on a macrotidal beach at Cayeux-sur-Mer in northern France. Deployment occurred on three separate days at three locations: on the upper, the middle and the lower part of the beach, down to depths of ~ 30 cm. The recovery rates varied from 26% after one tide to 95% at the end of the experiments. The pattern of pebble behaviour after one tide on the lower, middle and upper parts of the beach seemed to be consistent. Pebbles injected on the lower and middle beach showed a clear longshore displacement whereas pebbles injected at the top of the beach were mostly displaced cross-shore (seaward). The distance pebbles travelled varied with the location in which they were placed, with pebbles from the upper beach tending to travel further than pebbles placed in the middle and lower parts of the beach. Wave conditions and water level also influenced pebble movement.

The progressive thinning of sandy beaches in NW Portugal has exposed: large areas of rocky outcrops in the low tide and sub-tidal zones; older marine deposits in the sub-tidal zone; and older beach deposits in the foreshore. All these environments were previously covered by sands. As a result, sandy beaches have progressively been replaced by shingle beaches. This phenomenon migrates from north to south along the coast. Morphological change generally pass through a state where sand and gravel coexists in a beach cusp morphology (the beach horns being made of pebbles) until the sand disappears and only pebbles, cobbles and boulders remain. The main purpose of this study is to understand shingle behaviour under different wave climate conditions and the mechanisms that led the shingle beaches to be more stable than the sandy beaches they replaced.

This study investigated the effects of bulkheads and other armoring on beach conditions in Thurston County, Washington. Beach characteristics were measured at paired beach sites — neighboring and otherwise similar sites with and without bulkheads or other armoring. The study focused on beach characteristics relevant to spawning habitat for pacific sand lance and surf smelt, known as forage fish because of their importance to salmon. Armored locations, particularly in reaches of the shoreline where armoring was common, were found to have narrower beaches, with the greatest loss of beach typically at the higher elevations. Beach slope and sediment size were not significantly affected by the armoring. In a separate GIS-based investigation, it was determined that smaller, typically unnamed creeks contribute insignificant amounts of sediment in this area compared to the potential sediment supply from larger rivers or (most likely the largest contribution) from landslides and other mass wasting.

Extreme storms in reef environments have long been recognized as a mechanism for depositing ridges of reef-derived coarse clastic sediment. This study revisits the storm ridges formed by Tropical Cyclone Bebe on Funafuti, Tuvalu and Tropical Cyclone Ofa on Upolu, Western Samoa in the South Pacific, and Hurricane Lenny on Bonaire, Netherlands Antilles in the Caribbean. Ridge characteristics produced by these storms include: heights of 1–4 m, widths of 8–50 m, and lengths up to 18 km. The ridges tend to be higher and steeper on their landward margins than on their seaward margins and are composed mostly of re-worked coral rubble derived from reef front settings with smaller amounts of fresh broken coral (5–30%). Characteristics of these modern gravel storm ridges can be used to help identify ancient storm deposits and to differentiate between other coarse-grained deposits such as those created by tsunamis.

A data set consisting of detailed measurements of the hydrodynamics, morphological and sedimentological change, and sediment transport, has been collected from the region of the beach step on a macrotidal gravel beach. The step is an accretionary feature which evolves with a different relaxation time to that of the berm. Initiation of the step requires relative tidal stationarity and is thought to be triggered by increasingly reflective conditions. Despite its location, the step has remarkably stable sedimentology, differentiated from the swash zone using sedimentary moments. Co-spectral analysis indicates that sediment transport in the region of the step is related to sub-incident wave frequencies. A reconstructed ensemble sediment transport event confirmed that sediment transport at the base of the step occurs as a negatively skewed wave, perhaps sensitive to wave groups. The transition matrix of the nearshore gravel bed motion data closely resembled that of a ‘memoryless' queuing process.

Morphological model computations based on uniform (non-graded) sediment revealed an unrealistically strong scour of the sea floor in the immediate vicinity to the west of Maasvlakte 2. By means of a state-of-the-art graded sediment transport model the effect of natural armouring and sorting of bed material on the scour process has been examined. Sensitivity computations confirm that the development of the scour hole is strongly reduced due to the incorporation of armouring processes, suggesting an approximately 30% decrease in terms of erosion area below the –20m depth contour.

Recently, the influence of wave periods on dune erosion was studied in a series of large-scale physical model tests. In these tests dune erosion was simulated under extreme storm conditions. The aim of the study presented in this paper was to develop dune erosion prediction methods that take effects of wave periods on dune erosion into account. An existing dune erosion prediction method was used as starting point for the development. The obtained prediction method will be used to evaluate the dunes along the Dutch coast, where longer wave periods occur than previously assumed.

A modification of the equilibrium beach profile scale parameter is proposed to account for wave effects. The modification is expressed in terms of a multiplication factor applied to the profile scale parameter and considered to be a function of the fall velocity parameter. The recommended modification is based on large-scale wave flume tests. The differences between summer and winter profiles in nature can be explained qualitatively by the proposed model and the application of the model to predict seasonal shoreline changes is promising.

This paper evaluates shoreface change in response to a decrease in sediment supply over three timescales — Holocene (millennia), historical (century), and contemporary (interannual). The reduction of sediment supply is due to northern migration of the Columbia River ebb-tidal delta over the past few thousand years and construction of jetties during 1885–1917. Data analyzed include shoreface vibracores, historical regional bathymetry since 1868, and upper shoreface and beach profiles since 1997. At late Holocene to historical time scales the lower shoreface eroded while the upper shoreface and barrier accreted. At recent interannal time scale, the primary dune prograded. This behaviour resulted in a net rotation (i.e., steepening) of the shoreface and implies onshore sediment supply from the lower shoreface to the barrier. The study area is along northern Clatsop Plains, Oregon, USA.

Louisiana's barrier islands provide not only habitat but protection for interior marshes. The loss of these islands would expose interior marshes to increased wave heights, flooding, and loss of wetland habitat. The restoration of Louisiana barrier islands poses a combination of challenges, starting with quantifying project goals, developing a project design based on meeting those goals, through to construction of the project. This paper outlines design and construction details unique to Louisiana barrier islands using East Grand Terre and the Chaland Headland Restoration CWPPRA projects as case studies.

Two instrumented platforms were deployed for over two months on the shallow (<8 m depth) Atchafalaya shelf in Spring 2006. The instruments monitored wave, sediment and current evolution throughout the entire water column. High-resolution measurements of near-bottom velocity and suspended sediment concentration show clearly the formation and erosion of fluid mud layers in response to wave and current forcing.

Although basic causes of barrier island retreat and area loss of Louisiana Barrier Islands are known, there has been limited success in unraveling and quantifying how these processes interact to generate observed barrier island behavior. Processes that make up a conceptual-analytical dynamic morphosedimentary model (DMSM) are evaluated here using a process-based numerical model. The model is specifically used to investigate the morphodynamic behavior of non-cohesive (sand) and cohesive (fines) sediments under different hydrodynamic conditions (mild waves, cold fronts and tropical storms). The primary modeling focus is on the seaward limits of sand deposition during high wave energy conditions and the selective deposition of different grain sizes (sand, clay and silt, and mixed sediments) during low wave energy conditions.

In an effort to more accurately evaluate sand volumes that are potentially available for coastal restoration, high-resolution geophysical data were collected followed by detailed geotechnical investigations in two study areas in Ship Shoal Complex. Interpretation of vibracores helped to identify about 13.2 x 10⁶ m³ of clean sand (<5 % silt: D₅₀ ~0.20 mm) in portions of Ship Shoal Blocks 88 & 89. Geotechnical exploration of South Pelto Blocks 12 & 13 also identified mostly clean sand (D₅₀ grain size 0.15 to 0.2 mm) with less than 5% silt in upper stratigraphic units 4 to 6 m thick. Combined volumes of three closely spaced potential borrows amounted to approximately 21.6 x 10⁶ m³. Comparison of sediments on emergent barrier islands with those on the drowned barrier known as Ship Shoal indicates a high level of compatibility for restorative work on Isle Dernieres and Lafourche delta coastal segments.

Coastal land loss in the Mississippi River delta region contributes to loss of valuable habitat and coastal flooding hazards. Restoration of these ecosystems is a primary activity that requires large volumes of sand to rebuild beach-dune systems and restore wetland habitats. Sand sources have traditionally been sought offshore in the marine environment but there are problems associated with setbacks from oil and gas infrastructure, presence of muddy overburden, and limited reserves of beach-quality sediments. The potential of sand sources in channel and point bar deposits becomes an attractive alternative for barrier island restoration, especially because fluvial sediments are renewable. Results of preliminary geophysical and geotechnical investigations in the lower Mississippi River (south of New Orleans) along a 32-km stretch of the river indicate the presence of at least 23 million m³ of usable sand.

Engineering works on the Mississippi River constrain the River in its present course and prevent flood waters from overflowing the river banks. Thus, very little of the river's sediment load goes into the wetlands, with the major fraction transported off the edge of the continental shelf into deep water. A realistic approach is presented that reconfigures the arrangement of structures at the Old River Complex so that a predominance of the sediment load would go down the Atchafalaya River where it would be deposited in the shallow waters of Atchafalaya Bay, thus creating a large expanse of marsh lands that would help to compensate for the loss of wetlands in the rest of southern Louisiana. The purpose of this paper is to advocate for a comprehensive analysis, in the form of a feasibility study, of the benefits and drawbacks of redirecting the sediment load at Old River.

Land-building sediment diversions, such as the Mississippi River Diversion at West Bay, are being used as important building blocks in the conservation and restoration of Mississippi Delta wetlands. We have studied sediment deposition and retention in the West Bay diversion outfall area through analyses of sediment cores, bathymetry, and hydrodynamics. Cores and x-ray samples were collected at twenty stations in March 2004, August 2004, November 2005, and April 2006. Cores were sub-sampled in 2 cm increments and analyzed for grain size distributions and ⁷Be activities which can be linked to recent sediment deposition. Bathymetric surveys were conducted in November 2005 and April 2006 and will be used to compare significant elevation changes to bay bottom contours. Data analysis for the study focuses on the ⁷Be results in comparison with hydrodynamic forcing functions such as river and diversion flows and major storm activity.

This paper presents the results of a numerical model study on initial delta formation in basins of different water depths. A process-based model (Delft3D-Online) is used to calculate fluid flow and sediment transport patterns at a newly formed river effluent. In absence of wave and tidal forcing, the river effluent is fully river dominated. The model results are interpreted in terms of morphology and stratigraphy. For the shallow basin case, the delta develops as a complex, pattern of channels and shoals analogous to Wax delta. The simulated delta development in the deep basin is markedly different and resembles a classic prograding bird foot delta morphology. Typical clay-rich prodelta deposits underlie sandy bar and channel deposits. The top of the sedimentary sequence consists of a clay-rich delta plain deposit. The potential of the process-based model to simulate typical delta morphologies and a realistic stratigraphy provides many new opportunities to bridge typical engineering and geological research approaches.

Over the past several thousand years the Mississippi River has formed one of the world's largest deltas. However, over the last 100 years or so this system has been deprived of most of the sediments vital for its regeneration and maintenance due to organized human interventions (e.g., levees). As a result, the natural channel shifting necessary for replenishment of the delta with fresh sediment is severely impeded. River and sediment diversions are being proposed as way to re-create the historical delivery of river water and sediments into the delta region. Two complementary tools useful for studying diversions are physical models and numerical modeling. First, we present some details and result from a distorted scale, movable bed physical model designed to provide insight into potential river and sediment diversions. We then present some approaches being taken to develop numerical models aimed at providing insight that cannot be obtained using the physical model.

Coastal morphodynamics are evaluated to develop a more-advanced geomorphic model for chenier-plain evolution in southwestern Louisiana. Most ridges on the chenier plain represent open-Gulf paleoshorelines. Past movement trends of individual shorelines allow ridges to be further classified as transgressive, regressive, or laterally accreted. As such, a geomorphic hierarchy of landforms is refined relative to dominant coastal process. To understand long-term evolution of the chenier plain, modern tidal-inlet processes operating at Sabine Pass, Calcasieu Pass, and the Mermentau River mouth are examined relative to the inlet-stability ratio; historical shoreline-change data are used to document trends in. shoreline behavior; and air-photo interpretation and topographic profiles are used to address form/process relationships of primary landforms. These datasets and others indicate that the geologic evolution of the chenier plain is more complicated than just channel avulsions of the Mississippi River and downstream delta switching. A six-stage geomorphic process-response model is presented that synthesizes chenier-plain evolution primarily as a function of: 1) the balance between sediment supply and energy dissipation, 2) local sediment reworking and lateral transport, and 3) tidal-entrance dynamics.

Conceptually, the goals and engineering design associated with beach nourishment are very similar to those required for habitat restoration, with the primary component of both being placement of fill material. Similar analyses are required for characterization of historic geologic and environmental conditions, assessment of sediment compatibility, development of design and construction templates, application of coastal structures, and other design elements. With some modification, many of the design methodologies developed for beach nourishment can be adapted to the less-established field of wetlands restoration.

Louisiana has embarked on the nation's most ambitious program to restore and protect their ecosystems, wetlands, and wildlife; provide storm protection; and support oil and gas development. Storm erosion has breached the majority of the barrier islands resulting in the development of fragmentary islands and new inlet openings. Environmentally sensitive marsh habitats have declined due to man's impact from oil and gas mining and Mother Nature's effects. One key strategy within the program is marsh restoration to stabilize the integrity of the barrier shorelines. Success criteria mandates that by Year 3 the marsh platform elevations are within the intertidal zone, defined from Mean High Water to Mean Low Water, and remain within this zone through Year 20. Critical steps in the platform design process include subsurface data collection, back-barrier sediment analyses, containment dike design, and prediction of the target platform elevation to achieve the success criteria.

Ice-rafting of sediment is a major winter process in New England coastal marshes, increasing in intensity northwards. A survey of ice rafts conducted across three back-barrier salt marshes characterizes and quantifies sediment loads. The mean concentration of sediment in ice rafts increases to the north: 10.4g/L at Nauset, MA; 20.3g/L at Essex, MA, and 26.2g/L at Wells, ME. Inorganic sediment dominates 70% of ice rafts sampled. Ice raft dispersion across the marsh surface, while highly stochastic, is influenced by tidal amplitude, channel network density, meteorological. conditions, and marsh surface elevation. A numerical model of ice-rafted sediment deposition on New England salt marshes is derived. Mechanisms of ice raft sediment incorporation and dispersion, conceptual models of ice raft formation, and estimates of the relative magnitude of vectors are presented, with implications for the vertical accretion of northern marshes in a regime of rising sea level.

The Nauset barrier spit breached during a strong Northeast storm in January 1987, creating a new tidal inlet. Nauset Beach has historically undergone an approximate 135 year cycle of spit elongation followed by breaching and new inlet formation. The creation of the tidal inlet resulted in dramatic changes to the hydrodynamic processes within the Pleasant Bay estuarine system including an increase in tidal range, tidal currents, formation of ebb and flood tidal deltas, and an increase in wave energy transmitted into the previously quiescent back-bay region. A notable change was a loss of fringing salt marsh within the estuary. In the 10 year period after the breach there was a 14% decrease in fringe marsh followed by a 5% and 12% increase during the next 11 years. Since 1998, the Town has removed approximately 482,000 yd³ of dredged material that has been used to maintain unarmored important Town beaches along the interior shoreline.

In natural conditions, the dynamics of the Danube delta coast has been largely determined by the interaction between fluvial deposition and a strong southward wave-induced longshore transport near the mouths of the river. River-mouth morphodynamics is highly nonlinear, involving multiple feedbacks on the longshore sediment transport. These include a groin effect of the river plume and subaqueous delta, a shoaling effect of the downdrift offset subaqueous delta, and a barrier steering effect of the downdrift barrier islands or spits. As a result, a net sequestration of sediments occurs near the river mouth that aids and speeds up delta lobe development. Downdrift of the mouth, barriers may form after extreme river floods, but also due to increased shoreline instability under high angle waves. Although river mouth processes are complex, the resulting morphology of wave-dominated delta lobes exhibits a tendency to self-organize.

Field observation on coastal and river mouth morphology change in Sri Lanka induced by 2004 Indian Ocean Tsunami has been carried in May 2005 by a survey team delegated by the Committee on Hydroscience and Hydraulic Engineering, Japan Society of Civil Engineers (JSCE). The survey area covers southeastern, southern and southwestern parts of Sri Lanka. It is found that dependent on the tsunami waver height and vegetation condition covering the sand surface, various level of erosion has occurred along the coast.

Recent multi-beam, backscatter, and bottom sediment data demonstrate that a large sand sheet was formed in the inner shelf by the reworking of the Merrimack River lowstand delta and braid plain (12 kya) during the Holocene transgression. Seismic data reveal the presence of widespread channel cut-and-fill structures landward of the delta suggesting that much of the sand sheet consists of braided stream deposits. These features map into several sets of cut-and-fill structures, indicating the avulsion of the primary river channels, which creates the lobes of the paleo-delta. Truncations of these, cut-and-fill structures suggest that the braid plain deposits were probably reworked during the Holocene transgression and may have contributed sand to developing barriers that presently border the Merrimack Embayment.

The Santa Clara River, draining one of the largest watersheds in Southern California (1,634 sq-mi [4,232 sq-km]), is a major source of coastal sediments. Future development on the watershed has the potential to alter sediment delivery and cause erosion both along the coast and within the River. Unfortunately, long-term, historic sediment transport data is unavailable for Santa Clara River. Because of the paucity of the available data, an alternative means of determining a baseline geomorphic and sediment delivery condition is needed. Time dependent geomorphic change was calculated based on topographic data dating from 1906 to 2005. At least one cross-section was chosen for each hydraulically distinct subreach of the study area. A sectional analysis based on elevation change of the bed (area computation of the section) was conducted to determine time dependent geomorphic change. Analysis finds that sections show geomorphic change between 1947 and 2005 ranging from –8.0 to 3.1 feet (–2.44 to 0.95 m).

Box cores collected on the Louisiana continental shelf immediately following Hurricanes Lili and Katrina allow comparison of sediment event layer formation on the actively accreting Mississippi delta adjacent to Southwest Pass (Katrina) and the Atchafalaya delta (Lili). Post-Katrina box core sites in water depths of <40 m show evidence of an erosional surface at the sediment-water interface, indicating the water depth that critical erosion stresses are found in these large storms. Erosional deflations from Katrina and Lili ranged from 2–15 cm, controlled by water depth (shallower caused greater incision) and degree of consolidation of the pre-existing seabed sediments. In water depths of >25 m, post-Katrina cores display event layer deposition 1–25 cm thick above the incision surface: post-Lili cores from the Atchafalaya show similar thicknesses dependent on proximity to the storm path, but also extending into shallower water (shallowest station sampled was 4 m).

As part of an ongoing cooperative effort between USGS, NASA and USACE, the barrier islands within the right-front quadrant of Hurricane Katrina were surveyed with airborne lidar both before and after landfall. Dauphin Island, AL was located the farthest from landfall and wave runup intermittently overtopped its central and western sections. The Gulf-side of the island experienced severe erosion, leaving the first row of houses in the sea, while the bayside accreted. In contrast, the Chandeleur Islands, LA did not experience, this classic ‘rollover'. Rather, the island chain was completely stripped of sand, transforming a 40-km-long sandy island chain into a discontinuous series of muddy marsh islets. Models indicate that storm surge likely submerged the entire Chandeleur Island chain, at least during the latter part of the storm. The net result was destructive coastal change for the Chandeleur Islands, while Dauphin Island tended to maintain its form through landward migration.

Coastal engineers typically use numerical models such as SBEACH to predict coastal change due to extreme storms. SBEACH model inputs include pre-storm profiles, wave heights and periods, and water levels. This study focuses on the sensitivity of SBEACH to the details of pre-storm bathymetry. The SBEACH model is tested with two initial conditions for bathymetry, including (1) measured bathymetry from lidar, and (2) calculated equilibrium profiles. Results show that longshore variability in the predicted erosion signal is greater over measured bathymetric profiles, due to longshore variations in initial surf zone bathymetry. Additionally, patterns in predicted erosion can be partially explained by the configuration of the inner surf zone from the shoreline to the trough, with surf zone slope accounting for 67% of the variability in predicted erosion volumes.

The landfall of Hurricane Rita in 2005 significantly altered physical and morphological characteristics along the southwestern Louisiana coastline and interior marshes. An excessive storm surge event linked to Rita resulted in widespread, storm-induced overwash deposits in Cameron and Vermilion Parishes, Louisiana. These deposits superseded prior deposits and were aligned parallel to predominant flow patterns associated with the storm's counter-clockwise circulation. These responses became more pronounced farther west and culminating at eyewall impact. Excessive salinity levels resulting from salt-water intrusion severely impacted local vegetation several kilometers inland and over the longer term may exacerbate the loss of vegetation that retards coastal erosion and attenuates waves and storm surge during high-energy events. Massive water levels introduced onshore by surge remained locally ponded several weeks after the hurricane; however, morphological patterns along the coastline had begun facilitating the return flow of water and sediment to the Gulf of Mexico.

Ship Shoal, a shore-parallel elongate sand shoal and a remnant of a late Holocene active delta has a unique heterogeneous sedimentary feature strongly affected by winter storms and fluvial sediment input from the Atchafalaya River. The interaction between fluvially derived sediment and subsequent deposition on the shoal has not been quantified; implications for hydrodynamic modeling are profound given that the shoal surface vacillates between sand and fluid mud. Thus, attenuation effects on waves and currents vary greatly. The results of a field survey undertaken during spring flood and winter storm periods showed that during fair weather, river-borne sediments transported to the shoal, forms a distinct fluid mud layer. Bottom sediments were re-suspended and transported by storm-induced waves and prevailing northerly/southerly trends of currents over the shoal during the period. Data presented here suggest that the high sediment transport during the storms and the ephemeral deposition of fine-grained sediments could form transient sediment distribution on the shoal without leaving any modern sedimentary records, as reported by recent core surveys.

Here we present data indicating the complexity and highly variable response of barrier islands and beaches to the impacts of tropical cyclones and winter storms along the northern Gulf of Mexico. Data indicate that (1) barrier islands can conserve mass during catastrophic hurricanes; (2) less severe hurricanes and tropical storms can promote rapid dune aggradation and contribute sediment to the entire barrier system; (3) cold fronts play a critical role in the post-storm adjustment of the barrier by deflating the subaerial portion of the overwash terrace and eroding its marginal lobe along the bayside beach through locally generated, high frequency, steep waves; and (4) barrier systems along the northern Gulf do not necessarily enter an immediate post-storm recovery phase, although nested in sediment-rich nearshore environments. The fluid mud environment off west Louisiana coast plays a significant role in damping wave energy associated with tropical cyclones. However, no significant surge attenuation appears apparent. It is anticipated that these findings will have important implications for the longer-term evolution of coastal systems in the northern Gulf of Mexico.

The morphologic and volumetric changes of the dune foot, beach and inner nearshore zone over a major storm are studied on Egmond beach. The shoreline configuration of this beach showed an alongshore variation of embayments and horns, with an alongshore spacing between 400 and 700 m and a cross-shore amplitude of about 25 m. The response of the dune foot and intertidal beach was closely coupled to this alongshore variation, with major changes in the embayments (more reflective conditions) and small changes at the horns (more dissipative conditions). Overall, the upper beach and dune foot were eroding and flattened and the lower intertidal beach was accreting. The inner nearshore slope showed a steepening and a landward movement of e.g., the –3 m depth contour. The mechanisms that caused the changes are discussed and coupled to observed water levels in the nearshore These water levels altered and shifted the location of the transformed waves (asymmetric waves, breaking waves, bores and swash) in a cross-shore direction over the profiles.

A twenty-year (1978–1998) record of open-coast atmospherically-induced water level fluctuations at the US Army Engineer Field Research Facility (FRF) at Duck, NC has been analyzed and correlated to the occurrence of both cyclonic and frontal storms. The time-series and statistical clustering of water level excursions from the predicted tide have been analyzed. The analytical technique and findings presented here reveal significant information on the characteristics of individual storm surge hydrographs and on both short and long-term climatic trends. A classification model for characterizing storm hydrographs is presented along with selected statistical summaries of water level and storm trends. The techniques presented here provide a simple method for assessing climatic variability and storm cycle trends using frequently available continuous tide records. A Storm Intensity Index parameter, bases solely on water level deviations is presented. This study suggests an approach to link shoreline evolution to metrological patterns.

Hindcasts of the coastal impact of Hurricane Ivan on Santa Rosa Island, Florida, using a storm-impact scaling model that compares hurricane-induced water levels to local dune morphology, were found to have an accuracy of 68% in predicting the occurrence of one of four impact regimes: swash, collision, overwash, and inundation. Errors were overwhelming under-predictions of the regime where the observed response was more extreme than had been expected. This is related to the evolution of the profile during the storm. Mean pre-storm dune elevations decreased by 1.9 m over the 75-km long island as most of the dunes were completely eroded during the storm. Dramatic morphologic change during a hurricane makes barrier islands more vulnerable to overwash and inundation than will be predicted based on pre-storm dune parameters. Incorporation of the timing of rising water levels relative to storm-induced profile evolution is required to improve model accuracy.

Hurricane Ivan, a Category-3 hurricane, came ashore near Gulf Shores, Alabama, on September 16, 2004. Santa Rosa Island, Florida, was within the Northeast quadrant of the storm and subject to surge heights in excess of 3 m. As a result the area suffered significant sediment loss (>200 m³ m^–1) and widespread overwash and breaching. Morphological changes were quantified by comparing LIDAR images collected before and after landfall. In general, the morphological changes exhibited an alongshore variation at a range of scales (<1 km), consistent with the variation in foredune height prior to the storm. Using multivariate statistics it is found that this variation not only depends on the height of the foredune (relative to the surge elevation) but also on the alongshore extent of the dune and the presence and relative location of the secondary dunes. This alongshore variation will affect the recovery of the dunes, reinforcing the observed patterns.

The hydrodynamic response of Terminos Lagoon to the passage of Hurricane Isidore is presented. The field data analysis shows the changes of the hydrodynamic currents in the Carmen and Puerto Real inlets, as well as the water level elevation in the marine front and the interior of the Terminos Lagoon, due to the storm surge from the ocean, and the large fresh water discharges from land to the lagoon. Finally a brief interpretation of the system behavior is made, showing that in spite the large distance between the lagoon system and the hurricane trajectory (250 km), important effects in the hydrodynamics and sediment transport rates were reported. The identification of the hydrodynamic and sediment transport response to extreme events can help to better understand the physics of such systems, and can be applied to water quality, and mass transport studies in semi-enclosed coastal bodies.

Quantitative estimation methods for tsunami damage to houses and humans are proposed in consideration of beach transformation and dike failure. Case studies were conducted for Kochi Coast, Japan, where dike subsidence caused by earthquake motions, topographical change by tsunami, and dike failure by toe scouring is expected. Damage to houses and humans on land increases with dike subsidence and dike failure, and public awareness of evacuation had a significant influence on the extent of human damage. The methods used in this study quantitatively evaluated the mitigation of tsunami damage achieved by making, coastal dikes earthquake- and tsunami-resistant, and raising the level of evacuation awareness.

A study of morphological response and development of beaches which were affected by the earthquake and the tsunami on 26^th December 2004 has been conducted at two selected coastal sections of Banda Aceh, Indonesia. A simplified principle adopted from one-line shoreline theory in a geospatial analysis utilizing identified shoreline features across the foreshore zone is applied. The analysis yields a rough estimation of the shoreline and sediment volume changes since the tsunami. After the severe impact as revealed by a significant chaotic shoreline retreat, the morphological development in the following 6 months has shown that about 15% of the total sediment loss due to the tsunami on the northwest coast has further been eroded, while 60% of that on the west coast has been compensated by accretion. This leads to a conclusion that different coastal characteristics show different responses to, and developments after the tsunami.

Analysis of modern and past tsunamigenic features from within New Zealand and around the world have identified a suite of tsunami-related geomorphological features in dune systems including; Pedestals — remnant sections of dune ridge separated by scoured areas; Hummocky topography/Sand sheets — formed landward from pedestals (hummocky topography is the old, weathered equivalent of sand sheets); Parabolic dune fields — remobilised sand sheets landward of pedestals; Low Profile Sequences — post-tsunami feature indicative of changes to coastal sediment budget. The type of features formed by a tsunami, and the ability to detect and interpret tsunami geomorphology by LIDAR (and also in the field) hinges on the interactions between five key criteria; the availability and type of sediment (e.g. sand/gravel); embayment type; aprograding or eroding coast; small or large accumulation space; and whether there is a wet or dry landward environment.

Washover deposits induced by Hurricane Ivan are examined along a 260-km stretch of northern Florida coast. Initial response to the overwash event is dominated by dramatic nearshore, beach, and dune erosion. Eroded sediment is in-turn redistributed landward across the barrier-island profile. Distinct sedimentological characteristics of the washover deposits are recognized in different barrier-island sub-environments. Deposits on the beach are bound by a basal erosional surface, and exhibit planar seaward-dipping stratification. Over the barrier interior, preservation of fresh, in-place vegetation below the washover indicates that limited erosion occurred prior to washover deposition landward of the foredune. Washover deposits over the interior platform are characterized by horizontal to sub-horizontal stratification. Increased accommodation space landward within flooded interior wetlands and the back-bay yields substantially thicker washover deposits characterized by steeply inclined sigmoid and tabular foreset stratification. Back-bay deposition locally accounts for 120 m of landward bayside-shoreline migration.

The 2004 Indian Ocean tsunami caused major landscape changes along the southwest coasts of Sri Lanka that were controlled by the flow, natural topography and bathymetry, and anthropogenic modifications of the terrain. Landscape changes included substantial beach erosion and scouring of return-flow channels near the beach, and deposition of sand sheets across the narrow coastal plain. In many areas tsunami deposits also included abundant building rubble due to the extensive destruction of homes and businesses in areas of dense development. Trim lines and flow directions confirmed that shoreline orientation and wave refraction from embayments and rock-anchored headlands locally focused the flow and amplified the inundation. Tsunami deposits were 1 to 36 cm thick but most were less than 25 cm thick. Deposit thickness depended partly on antecedent topography. The deposits were composed of coarse to medium sand organized into a few sets of plane parallel laminae that exhibited overall upward fining and landward thinning trends.

Tsunamis frequently leave a characteristic sediment deposit on the inundated land surface, which can be interpreted to deduce some of the features of the original tsunami wave. A simple trajectory-based theory of the tsunami hydrodynamics and sediment dynamics is presented here, yielding expressions for the landward variations in thickness and sediment composition of the deposit. Each grainsize contribution to the deposit thins linearly landwards, with the sediment run-up limit increasing with decreasing grainsize. The expressions can be fitted to observed sedimentary characteristics to deduce the run-up height and distance of the water. Example applications of the theory are given for the 1929 "Grand Banks" Tsunami, and the Holocene Storegga Slide Tsunami. Reconstruction of palaeo-tsunamis can help with assessments of present day risks from tsunamis.

In numerical simulation of tsunami, the changing topography must be taken into account for some specific problems such as run-up over coastal dunes. In this paper, a numerical model for tsunami flooding over movable topography is presented. The model is based on the Boussinesq-type equation coupled with the sediment advection equation and existing empirical formulas for sediment transport. Laboratory experiment is conducted for the model verification on fixed bed, while its performance on movable bed is examined through comparison with available data. Finally, the dune erosion induced by tsunami is discussed on the basis of the model results.

Where a steep slope blocks an inrushing tsunami, the tsunami commonly reverses direction as a reflected bore. A simple method for relating vertical and horizontal variation in sediment size to output from numerical models of depth-averaged tsunami flow yields predictions about the sedimentary record of reflected bores: 1. Near the reflector, a abrupt slowing of the flow as the reflected bore passes is recorded by a normally graded layer that drapes preexisting topography. 2. At intermediate distances from the reflector, the deposit consists of a single normally graded bed deposited preferentially in depressions, possibly including a sharp fine-over-coarse contact. This contact records a brief period of erosion as the front of the reflected bore passes. 3. Far seaward of the reflector, grading in the deposit includes two distinct normally graded beds deposited preferentially in depressions separated by an erosional unconformity. The second normally graded bed records the reflected bore.

Field measurements from Sumatra of tsunami wave height, erosion and deposition form a comprehensive data set that is tested against the Delft3D tsunami inundation and sediment transport model. Relative agreement between measured and modeled maximum water levels and sediment erosion and accumulation provides confidence that the model is reasonably characterizing the important processes of tsunami inundation. Adding a component to account for vegetation, the model is used to explore the effects of fringing mangrove forests on tsunami inundation and sedimentation. In model experiments, mangrove forests modify the water levels and flow speeds reached during tsunami inundation. Simulations with a mangrove forest result in sedimentation in the forest and not erosion, as occurs in the base case with no forest. This difference in sedimentation is important because the change in profile shape increases wave energy reflection off the beach and decreases wave energy penetration onto land.

The coast of the western part of The Netherlands changed from a transgressive, tide-dominated system, characterised by tidal inlets and tidal basins, into a prograding barrier coast, between 5500 BP and 3200 BP. Ypenburg, SW of The Hague, is situated on the seaward boundary of a transgressive tidal basin which evolved from a predominantly subtidal into a intertidal flat area. During this evolution the landward expansion of the basin stopped. The seaward side of the tidal flat area was reworked and built-up by waves; it formed a transgressive barrier. The limited thickness of the wave-dominated deposits and the lack of shells of open-marine molluscs indicate that this coast line was sheltered from open North Sea conditions. The infilling of the tidal basin and the associated decreasing tidal channel are the onset of coastal regression. The formation of a beach barrier further seaward was the start of coastal progradation.

Erosion of the 24 km-long escarpment cut into the unconsolidated Pleistocene glacial deposits of outer Cape Cod, Massachusetts, by wave action during the Holocene transgression has supplied sediment for construction of spits and barrier beaches to its north and south. The major escarpment landforms produced by the erosion are steep coastal bluffs (upper c. 20 m), beaches, and a more gently sloping shoreface (to a depth of c. 10 m). Using differential GPS methods supplemented with LIDAR data we have re-surveyed the bluff portion of the escarpment along cross-shore transects originally surveyed in 1887–1889. Comparison of the surveys indicates that the bluffs erode at an overall century-scale rate of c. 0.8 m/yr, and that the erosion rate increases alongshore north-to-south by a factor of two. We suggest that the resulting change in coastal orientation results from relative sea level rise over the outer continental shelf and associated increase in wave energy from the southeast.

An 8500-year Holocene simulation developed in GEOMBEST provides a possible scenario to explain the evolution of barrier coast between Rodanthe and Cape Hatteras, NC. Sensitivity analyses suggest that in the Outer Banks, the rate of sea-level rise is the most important factor in determining how barrier islands evolve. The Holocene simulation provides a basis for future simulations, which suggest that if sea level rises up to 0.88 m by AD 2100, as predicted by the highest estimates of the Intergovernmental Panel on Climate Change, the barrier in the study area may migrate on the order of 2.5 times more rapidly than at present. If sea level rises beyond IPCC predictions to reach 1.4–1.9 m above modern sea level by AD 2100, model results suggest that barrier islands in the Outer Banks may become vulnerable to threshold collapse, disintegrating during storm events, by the end of the next century. Consistent with sensitivity analyses, additional simulations indicate that anthropogenic activities, such as increasing the rate of sediment supply through beach nourishment, will only slightly affect barrier island migration rates and barrier island vulnerability to collapse.

Rates of relative sea level rise in excess of 1 cm/yr are forcing rapid landward migration of barrier/tidal inlet systems along coastal Louisiana. Additionally, the conversion of interior wetlands to open water increases tidal prism, resulting in barrier degradation by means of increased inlet cross-sectional area and sediment sequestration in ebb tidal deltas. Historical bathymetric maps (dating to the 1880's) and up-to-date bathymetric data for Little Pass Timbalier provide a time series that shows the morphological evolution of this tidal inlet. The historical evolution includes: landward and lateral migration of its main channel (44 m/yr and 28 m/yr, respectively); changes in inlet throat geometry; and formation of a new stable ebb channel. The inlet throat cross-sectional area increased from 3,117 m² in 1880 to 17,510 m² in 2005. The ebb tidal delta is prograding seaward leaving a quasi-progradational sand body on the inner shelf as the barrier islands migrate landward.

The Barataria barrier system within the Mississippi River delta plain, is experiencing some of the highest relative sea-level rise (SLR) rates in the continental USA (0.94 cm/yr). This has led to substantial wetland loss in Barataria Bay (16.9 km²yr, from 1935–2000). This conversion of wetlands to intertidal and subtidal environments results from several linked processes including subsidence, marsh front erosion, and catastrophic scour during large magnitude hurricanes. Increasing open water within Barataria Bay has amplified tidal exchange with the ocean. Between 1880 and 2006, an increase of 400% took place in the combined cross-sectional areas of the major tidal inlets of Barataria Bay, associated with the enlarging tidal prism. This expansion of the inlets has been at the expense of the adjacent barrier islands, evident in the concomitant progradation of the ebb-tidal deltas. Since the 1880's the ebb delta at Barataria Pass built seaward more than 2.0 km, sediment cores show that sand constitutes the upper 1–2 m of the ebb delta. Movement of sand offshore, regional subsidence and increasing bay tidal prism produce segmentation of the barriers, forming new inlets such as Pass Abel. Acceleration in eustatic sea level rise will lead to further wetland loss and thus ultimately barrier disintegration. The Barataria barrier chain will be transformed into an island-only system similar to the Isle Dernieres and Timbaliers.

Using a 1-m lidar digital elevation model and detailed wetlands mapping, we developed an inundation model that projects future wetland distribution caused by sea-level rise. Vertical accretion, edge erosion, and land-subsidence components are also included in the model. Applying the model to a section of Galveston Island, Texas, and using the actual annual record of ocean level recorded by a nearby tide gauge shows the complicated interplay of decadal-scale water-level variation and topography in determining the future distribution of wetlands. Total wetland coverage declines by 22% in 30 years but recovers to a net loss of just 5% within 90 years. Uplands transitioning to high-marsh wetlands more than offset the effects of inundation, allowing high-marsh wetlands to increase in coverage by 132%. Low-marsh wetlands, however, decrease by 77% at the end of the 90-year model period.

This paper uses historic bathymetry data for five UK estuaries to examine past morphological changes and to calibrate an equilibrium-based morphological behaviour model of estuarine evolution. After calibration, ASMITA is used to predict the maximum rate of sea-level rise (SLR_crit) which each estuary can experience without losing all intertidal areas. SLR_crit varies significantly between estuaries suggesting that some are quite vulnerable to sea-level rise (e.g., Southampton Water) and others are more resilient (e.g. the Ribble). Estuary area, sediment supply, sediment transport potential and human interference all appear to influence the sensitivity of an estuary to sea-level rise.

Researchers and coastal managers are addressing how climate change will affect shorelines. Important questions include: How far will a sandy shoreline retreat as sea level rise accelerates? And, how far landward will the effects of possibly intensified storms reach? These questions are most often investigated in a cross-shore profile framework, fostering the implicit assumption that coastline responses will be approximately uniform in the alongshore direction. However, we describe here experiments with a recently developed numerical model of coastline change involving shoreface geology and sediment-transport processes which suggest that the responses to sea-level rise are likely to be alongshore-heterogeneous. The interactions between accelerating sea-level rise, alongshore sediment transport, and spatially variable underlying material will tend to cause spatially variable retreat rates. We compare these sea-level-rise effects to other climate-change related shoreline impacts suggested by recent modeling work. Slott et al. have suggested that as storm behaviors and wave climates change, shifts in complex large-scale coastline shapes will cause alongshore variation in shoreline-change rates that could be an order of magnitude greater than sea-level-rise-related shoreline changes.

Kaanapali beach is a well-defined littoral cell of carbonate sand extending 2 km south from Black Rock (a basalt headland) to Hanakao'o Point. The beach experiences dynamic seasonal shoreline change forced by longshore transport from two dominant swell regimes. In summer, south swells (H_s = 1–2 m T_p = 14–25 s) drive sand to the north, while in winter, north swells (H_s = 5–8 m T_p = 14–20 s) drive sand to the south where it accumulates on a submerged fossil reef. The Delft3D modeling system accurately predicts directly observed tidal currents and wave heights around West Maui, and is applied to simulate shoreline change. Morphologic simulations qualitatively resolve the observed seasonal behavior.

Along many shorelines, the coastal foredune plays a key role in protecting against coastal flooding while providing a unique environment for specialized flora and fauna. Over the past 20 years, researchers with backgrounds in engineering, geography, geology, and geomorphology have expanded our understanding of the coastal aeolian processes that build and shape these landforms. In 2002, the U.S. Army Corps of Engineers (U.S.A.C.E.) replaced its Shore Protection Manual (SPM) with the Coastal Engineering Manual (CEM). The CEM is intended to provide "in a single source the current state-of-the-art in coastal engineering to provide appropriate guidance for application of techniques and methods to the solution of most coastal engineering problems", thus establishing it as the legal standard for coastal engineering practice in the U.S. Chapter 4 in Part III, "Wind-Blown Sediment Transport" is intended to provide engineers such guidance where wind blown sand is a part of the problem or the solution. This paper reviews Chapter III–4 and compares it to the published research to assess the degree to which this section communicates and codifies "state-of-the-art" understanding of coastal aeolian processes and landforms. Our review suggests that three specific areas require revisiting: (1) the "Transport Rate" section should be revised to direct the user to conservative transport rate estimation methods; (2) the coastal aeolian and dune process descriptions should be expanded to incorporate recent research findings, especially those that encourage and permit the engineer to incorporate more natural processes and landforms in solutions; and (3) an outdated and incorrect recommendation should be removed immediately.

The distribution of the horizontal distance traveled by the sand grains in saltation, which is equal to the distribution of the falling sand grain rate in the region from the end of the sand bed and down wind, is quite similar to the vertical distribution of sand transport rate above the sand surface. This observation is explained by assuming that the height of the trajectories of transported sand grains in the air is different but the trajectories are similar in form. The wind tunnel experiment showed that the equation for the distribution of horizontal distance traveled by the grains converted from the vertical distribution of sand transport rate can be applied.

At present, many beaches in Japan are experiencing severe erosion and prevention works to combat this erosion forces changes to the conventional works used to control wind blown sand in the past. Detailed field inspections were carried out of the wind blown sand controlling works and windbreaks at beaches in the central part of the main island of Japan. This study reports precious results obtained by the field inspections.

This paper analyzes the main characteristics of the aeolian dynamics and dune evolution in the Corralejo coastal dunefield. This is an area with limited sediment supply and subjected to the action of a quasi-unidirectional wind regime. The governing conditions induce a long-term migration of the dune field in the direction of the wind with an expected long-term change in the landscape due to a change in the sediment supply to the dunefield through the upwind end due to natural and human-induced factors.

Numerical model simulations of tidal inlet hydrodynamics, sand transport and topographic change were performed using the Coastal Modeling System (CMS) to investigate the morphological response to time varying forcing, sediment texture, and the influence of rock reef outcrops within the Sebastian Inlet system. The presence or absence of rock within the inlet throat and in the surf zone on the south side of the inlet resulted in distinctive differences in topographic changes to the ebb shoal over a year long simulation. Comparisons between three sand transport formulations over a shorter period (2 months) showed some variation among the formulations, but predicted net topographic changes were well within an order of magnitude. Comparisons between predicted and measured net topographic changes demonstrated agreement in terms of pattern. Agreement in absolute terms improved as the model spatial resolution was refined by decreasing cell sizes.

Cape Shoalwater, at the north side of the mouth of Willapa Bay, Washington, has experienced some of the most severe erosion in the United States, exceeding 30 m per year during most of the 20th century. Morphological studies have documented that the rate of shore retreat near the Shoalwater Reservation has slowed to almost zero since the mid- to late-1980's. The reason is the presence of outcropping hard strata, a very dense, brown Pleistocene Terrace unit. This finding was unexpected because previous studies suggested that the shoreline would continue to retreat and that there were unlikely to be any practical engineering solutions to help stabilize the remnants of North Cove. Water diversion structures, such as dikes are impractical because they would need to be massive to have any effect in controlling the ebb-and flood-currents. Wave analysis verified that the waves causing local flooding in the reservation were generated in the fetch of the bay and that Pacific Ocean waves are effectively dampened as they pass over the Willapa ebb shoal.

A comprehensive approach was used to evaluate recent changes to the St Lucie Inlet system and was used as the basis for the evaluating future sand transfer and shoreline stabilization projects associated with the region. The analysis relied extensively upon hydraulic, bathymetric, and coastal monitoring conducted over multiple years and dredging cycles to evaluate impacts upon the hydraulics of the St. Lucie Inlet and Estuary. The monitoring data was used to assess the effects of the impoundment basin dredging on tidal prism/circulation patterns, navigation, and shoaling patterns/sediment transport pathways. Analysis of coastal processes through the development of numerical modeling tools in the vicinity of the inlet provided baseline information for management decisions.

The North End Restoration Project uses a regional sediment management approach to address jetty-induced sediment deprivation and accelerated erosion on Assateague Island, Maryland. The biannual sand bypassing project dredges sand from the ebb and flood tidal deltas and places it in the nearshore area of the project site rather than on the upper shoreface, thereby replicating natural sediment transport processes and minimizing adverse impacts to subaerial habitats. Calm weather has prevailed since sand bypassing began, and accretion occurred at all depths within the placement area and at shallow depths to the north and south. Erosion occurred at lower depths and north of the ebb tidal delta attachment bar, which may block sand transport to the northernmost shoreface and where wave refraction over the ebb tidal delta and unique tidal circulation patterns contribute to upper shoreface erosion.

Empirical orthogonal function (EOF) analysis is applied to examine the morphological responses to jetty construction at the first entrance of Lake Saroma, Japan with a 14-year bathymetric survey data set. The result clearly shows that the erosion trend along the channel and the accretions of ebb shoal far offshore appear during and after the jetty construction. Moreover, the volume change around the entrance is investigated, and the result agrees with that from EOF analysis. The entrance was found to be stable in analyzing the relationship between the tidal prism and the cross-sectional area.

Different aspects of both the short- and long-term morphological evolution of Texel Inlet, and the underlying processes and mechanisms were studied, ranging from long-term descriptions of historic inlet evolution, 1550 A.D. to present, to detailed analyses of hydrodynamics and morphodynamics on the process scale using the latest state of the art process-based models. It is shown that the morphodynamic evolution of the inlet is governed by human intervention. At present a large sediment import (5–6 Mm³/year) prevails as a result of a second-stage adaptation process to the effects of Closure of the Zuiderzee in 1932.

The shoaling rate in Blind Pass entrance channel approximately equals the net southward longshore sediment transport rate. Most of the shoaling occurs along the northern side of the channel. Flow measurements and numerical modeling reveal that the ebb current is approximately twice as strong in the thalweg along the south side as compared to the rest of the channel. In contrast, the flood current is mainly uniform across the inlet and is stronger than the ebb flow over the northern portion. This flow-velocity distribution induced by a nearly 90-deg bend of the channel contributes to the shoaling pattern. Two years after the 2000 dredging, the shoal along the north side became shallow enough to induce wave breaking. Distinctive shoaling patterns influenced by seasonal wave climate were observed. Sediment deposition in the channel is closely related to the passages of cold fronts, which significantly increases the sediment supply by longshore transport.

The morphologic response of inlets that are part of a multiple inlet system, defined here as two or more coastal inlets connected to the same bay, is a complex problem. It has been thought that one inlet will eventually dominate, and that other inlets will close. Of course, in nature, there is a full range of situations and physical realities that complicate this situation. As more experience and historical information become available, various approaches can be tested. There may be multiple inlet systems serving a bay region that have naturally developed and coexisted for many years in some cases or there maybe newly developed multiple inlet systems whose inlets immediately respond to each other, with the more efficient inlet creating a decline in the size of the other inlet, probably at a varying rate proportional to their efficiencies. An example of this type situation at two inlets on the Guatemalan coast is examined in this paper.

This paper summarizes the limited existing guidelines for the establishment of sand bypassing discharges adjacent to tidal inlets. Two recent case studies are presented where discharge siting was analyzed via a review of the-littoral transport. Based on these case studies, rational procedures for discharge siting are proposed for any inlet and bypassing system.

Flood-tide deltas are dynamic features that are linked to the morphodynamics of the associated estuarine beaches and shorelines. Flood-tide delta morphodynamics remain largely unknown. Historic aerial photographs from Port Stephens, a ria-like estuary located in NSW (Australia), are analysed using Geographic Information System (GIS) techniques. Port Stephens is used as a case study to define flood-tide delta morphodynamics that will be applicable to similar systems elsewhere. The waterline is chosen to represent the evolution of the estuarine beaches because they are reflective in a microtidal environment. Boundary definition for the flood-tide delta needs further work since it is a submerged feature and the photographs have different quality and correspond to different tidal levels. It is suggested that image processing techniques may help to solve this problem in the future. More studies, both morphologic and hydrodynamic, are needed to establish the sediment paths and magnitudes within the Port Stephens flood-tide delta.

Scenarios for a new navigation channel to the port of Ostend (Belgium) are to be assessed. Regarding coastal sediments dynamics, two aspects are of importance: first the maintenance dredging of the navigation channel itself (functional aspect), secondly the impact on the surrounding environment. The latter involves primarely the impact on the morphology of the sea bottom and the impact on the turbidity of the coastal waters. Available results of in situ-measurements, numerical modeling and laboratory experiments for the Belgian coastal zone were gathered, as well as general scientific literature. It could be concluded that the state of knowledge on coastal sediment dynamics in the Belgian coastal zone is to limited to be able to completely validate a process-based numerical model. A simple semi-empirical model was built, that is able to represent the essence of the impact on coastal sediment dynamics of a new navigation channel.

Mangrove-habitat expansion has occurred rapidly over the last 50 years in the 800 km² Firth-of-Thames estuary (New Zealand). Mangrove forest now extends 1-km seaward of the 1952 shoreline. The geomorphic development of this muddy coast was reconstructed using dated cores (²¹⁰Pb, ¹³⁷Cs, ⁷Be), historical-aerial photographs and field observations to explore the interaction between sediment processes and mangrove ecology. Catchment deforestation (1850s–1920s) delivered millions of m³ of mud to the Firth, with the intertidal flats accreting at 20 mm yr^–1 before mangrove colonization began (mid-1950s) and sedimentation rates increased to ≤ 100 mm yr^–1. ²¹⁰Pb data show that the mangrove forest is a major long-term sink for mud. Seedling recruitment on the mudflat is controlled by wave-driven erosion. Mangrove-habitat expansion has occurred episodically and likely coincides with calm weather. The fate of this mangrove ecosystem will depend on vertical accretion at a rate equal to or exceeding sea level rise.

The inner shelf, shoreface and beach at Cassino, located in the southernmost sector of the Brazilian coastline, are characterized by marked differences in grain size and sediment composition compared to adjacent areas. This lateral heterogeneity in sediment properties controls the geomorphology of the inner continental shelf and shoreface, and influences the shoreline accretion rate and beach morphodynamic behavior along a 25 Km stretch of coast. Short-term effects are associated with episodic events of mud deposition on the beach during heavy storms that often result in strong gradients in hydrodynamic processes. These gradients in turn influence the morphodynamic behaviors on the sectors affected by the mud deposits and can create coastal hazards relating to beach usage. These findings are almost certainly applicable in other regions where significant sediment heterogeneity exists.

On August 29, 2005, Hurricane Katrina sent the largest-ever recorded storm surge into the central Gulf coast. The coastal surge penetrated more than 16 km (10 mi) inland in Jackson County to the east and Hancock County to the west. Wave destruction extended more that 1 km (0.6 mi) inland. Immediately after the storm, URS teams identified and surveyed 312 coastal high water marks (CHWM) in the three coastal counties. The USGS identified an additional 90 CHWM. These were checked, verified and surveyed to within 0.08 m (0.25 ft) vertical and 3.5 m (10 ft) horizontal. In this paper, the Hurricane Katrina storm surge is documented. By considering special features of both the oceanic and overland propagation of the surge it is possible the gain an understanding of why this storm surge was so much higher and spatially extensive than other previous major hurricane events along the coast.

Presently, 16 permanent inlets connect the inland coastal waterways and rivers to the Gulf of Mexico on the 560-km long coast of Texas. Processes controlling inlet stability in Texas are typically more complex than those acting on the Atlantic and Pacific Ocean coasts of the United States, where the astronomical tide dominates. The tide on the Texas coast is predominantly or fully diurnal and with small range; however, the large surface areas of most Texas bays produce large tidal prisms. Wind is strong throughout the year, either from the southeast in summer or as episodic northeasterly fronts in autumn and winter. Non-astronomical seasonal variations in water level are comparable to the tidal range of Texas bays. Creation of inlets on the Texas coast is ongoing for environmental, commercial, and recreational reasons, and this paper discusses the status and challenges posed to inlet creation, stability, and maintenance.

The paper presents results of a study conducted to identify the feasibility of restoring Cedar Bayou Inlet — a natural fish passage in the Texas Coastal Bend — to its historical, open conditions. The study included historical and new field data collection, empirical analysis, and numerical modeling as well as development and analysis of engineering alternatives. Through analysis and modeling, the connection between Cedar Bayou and Vinson Slough (an adjacent 22,000 acre wetland) was found to be a critical element in maintaining both inlets in an open condition. The primary element of the proposed engineering solution is the reconstruction of the historical connection between Vinson Slough and Cedar Bayou by opening the main channel through dredging. In addition, the dredged material is proposed be used beneficially to re-construction a submerged ebb shoal offshore of the mouth of the Cedar Bayou inlet, which promotes sediment bypassing of the inlet mouth and reduces channel sedimentation.

This paper describes an ongoing analysis of coastal and inlet processes at the mouth of the Colorado River Navigation Channel, Texas. A weir jetty system with impoundment basin down drift of the weir was constructed at the mouth of the Colorado River in 1985 to reduce the expected rate of dredging of the shallow-draft entrance navigation channel. The required rate of dredging has been about double the design estimate, however, due in part to diversion of the Colorado River away from its entrance to the Gulf of Mexico. A study is underway to better understand the processes involved, design a more efficient entrance, and provide the reduced dredging interval and volume originally desired, while placing the inlet processes within a regional sediment transport framework.

Matagorda Bay, Texas, is connected to the Gulf of Mexico by two inlets, Pass Cavallo and the Matagorda Ship Channel (MSC). Pass Cavallo is a natural inlet located at the southwest terminus of Matagorda Peninsula, and the MS C is an artificially cut, deep-draft federally maintained navigation channel approximately 7.2 km northeast. Pass Cavallo was historically stable until the 20^th century, when the tidal prism was first reduced in 1935 by division of Matagorda Bay due to deltaic progradation of the Colorado River, and later in 1966 as a result of the construction of the Matagorda Ship Channel. In response to these reductions in tidal prism, the entrance width at Pass Cavallo reached historical minimums as Matagorda Peninsula and Matagorda Island prograded into the inlet. Long-term stability and potential of possible closure of Pass Cavallo are evaluated through theoretical and empirical relationships, and long-term analysis of morphologic change.

In Jul 2005, Packery Channel was opened by Hurricane Emily during the second year of its construction. This inlet connects Corpus Christi Bay and Upper Laguna Madre to the Gulf of Mexico, and it is the first artificially cut inlet in Texas in 17 years. The inlet has remained open and navigable for shallow-draft recreational boats despite construction delays, and its parallel dual jetties were completed in Sep 2006. A physical process monitoring program was initiated prior to construction in 2003 to track the evolution of the channel, surrounding nearshore, and adjacent beaches. Maximum ebb current in the inlet often exceeds 1 m/s, and an ebb shoal has not yet formed. The shorelines adjacent to the jetties, as well as the seaward longshore bars, respond to seasonal changes in wind direction, hence direction of longshore sand transport. Shoreline change varies seasonally, but adjacent to the inlet the shoreline is nearly symmetrical.

Mason Inlet, situated between Figure Eight Island and Wrightsville Beach, N.C. was artificially relocated 850 m updrift of its former position at the southern terminus of a migrating barrier spit. Relocation that occurred in early 2002 was chosen from several management options due to the increased backbarrier infilling and southerly migration of the inlet that imminently threatened a resort complex and infrastructure on northern Wrightsville Beach. The relocated Mason Inlet provides an exemplary site to study the evolution and impacts of a recently relocated system from its inception while simultaneously assessing the relative success of the project. Jarrett's theoretical equation relating tidal prism (T_P) and cross-sectional area (A_C) appears to be a useful tool for estimation of the relocated Mason Inlet's T_P. However, ebb-tidal delta volume after 4.5 years remains well below the equilibrium volume predicted by Walton and Adams' model.

Ancão Inlet (Southern Portugal) was relocated in 1997 and almost 10 years after its opening has the morphodynamic characteristics and migration pattern predicted by several authors. Its eastwards migration is mostly caused by high W-SW storm events, where the downdrift migration of the channel is accompanied by updrift spit growth and both deltas migrate asymmetrically. The inlet migration rates were computed between three new surveys and several inlet parameters measured, revealing the highest migration rates since inlet opening, an a relative stable inlet cross-section area, width and maximum depth at inlet throat through time. Inlet migration rate was compared with storm events and results showed a relation of this rate with the diminishing of E-SE storm events and an increase of magnitude of W-SW storms. Also, during an unusually powerful ex-tropical storm which affected the study area, an ephemeral inlet breached updrift from Ancão Inlet. The new inlet was competing for dominance of the tidal prism with Ancão Inlet, however it closed after three weeks, showing the hydraulic efficiency of Ancão Inlet nine years after its relocation.

A peculiar feature of tidal channel networks is that their geometry (e.g. channel length, width, density) scales better with watershed area than tidal prism. Platform elevation has little control on network morphology, suggesting that relative platform deepening following sea level acceleration or sediment supply reduction will not cause significant changes to the channel network, despite field observations to the contrary. We explain this paradox with a numerical model of platform and channel network evolution that incorporates feedbacks between vegetation and physical sediment transport processes. In the model, platform deepening stimulates vegetation growth, leading to more stable channel edges. In this situation, channels deepen rather than widen, leading to channel morphologies that do not reflect tidal prism. In an environment where sea level or sediment supply changes have significantly altered the platform elevation, vegetation disturbance will lead to rapid network expansion as channels return to a form determined by tidal prism.

Both natural and anthropogenic factors have played a role in producing the present morphodynamic conditions at Big Sarasota Pass. This inlet, of unknown origin and age, is located between Lido Key, a recently nourished barrier island, and Siesta Key, a classic drumstick barrier island. Stabilization of the south channel margin in the 1960s has resulted in an increase in the southerly shifting of the ebb-tidal delta which has produced a narrow and shallow outer channel. This has caused inlet bypassing of sediment to move beyond the updrift end of the island as is typical of natural offset inlets. The nourishment of Lido Key on the updrift side of the inlet has further exacerbated this condition with the result being erosion on the north end of Siesta Key and considerable accretion several hundred meters to the south.

This paper documents the seasonal opening/closure features of tidal inlets and river mouths in a wave-dominated, micro-tidal environment along the central coast of Vietnam and discusses their formation, temporal morphological changes under typical conditions that are dominant in the dry and the wet season respectively. The interpretations are based on aerial photography, historical maps, satellite images and field observations. In addition a conceptual model of seasonal opening/closure features of tidal inlets in a wave dominated; micro-tidal environment under the influence of episodic river discharges is introduced and examined by numerical modeling.

Like ocean beaches, sheltered coastal areas experience land loss from erosion and sea level rise. In response, property owners often install structures that harden the shoreline as a way to prevent further erosion, but these structures cause changes in the coastal environment that alter landscapes, reduce public access and recreational opportunities, diminish natural habitats, and harm species that depend on these habitats for shelter and food. The National Research Council Committee on Mitigating Shore Erosion along Sheltered Coasts concluded that a regional management approach is needed to assess the costs, benefits, and cumulative impacts of structural approaches and to encourage erosion control alternatives that help retain the natural features, of coastal shorelines.

Field observations and model simulations are presented of the tidal flow over a scour hole at the mouth of the Dyfi Estuary, mid-Wales, U.K. This scour hole is maintained by locally high flow speeds resulting from convergence, and then divergence, of the flow over the hole. Fixed features of the local bathymetry may also have served to stabilise its location (over decades). Model simulations of steady flow over a variety of schematised pits of different elliptical shape on an otherwise flat bed are presented to show that shallow elongated pits can (almost) preserve the upstream flow speed at their centre point, making them potentially self-maintaining. Deeper pits reduce the flow speed and so will infill.

A numerical model for estimating the terrace topography changes caused by floods is introduced, by considering grain size of sediment discharged from a river. Applying this model to Fuji river-mouth, the sediment discharged during floods can be estimated with an aspect of quantity and quality. As the result, it was obvious that the major part of sediment discharged from Fuji river-mouth at floods is flushed out offshore in deeper than 20m depth, which can not contribute as the longshore sediment transport that nourish the neighborhood of the river-mouth.

We investigate the near-bed sediment dynamics, that occurs in the oscillating boundary layer, observed during the SandyDuck '97 field experiment, through use of the k-ε turbulence module GOTM. For most of the time, the value of the near-bed Richardson number of the high-energy events under examination exceeds the critical value of 0.25, suggesting suppression of turbulence by sediment-induced stratification. GOTM is used to simulate the onshore sandbar migration observed over a 5-day period during Duck'94 field experiment. Bar migration is predicted with a skill of 0.72 when including stratification effects. The accretion/erosion rates predicted using the same free parameters but neglecting stratification effects are approximately twice as large.

The Berau delta and barrier reef system, East Kalimantan, Indonesia are subject of an integrated and multidisciplinary research programme that studies the transfer of water and sediment from upland river catchments towards estuaries and offshore located coral reef systems. Estuaries in the Berau delta have a certain trapping efficiency but a significant part of the suspended matter is still able to reach the marine environment. Seismic profiles, isotope analysis for deposition rates, estuarine and offshore measurements of salinity and turbidity patterns and ecological evidence, collected during a pilot study, provide clear evidence for this.

It is well known that surface water waves interact with the fluid mud on the sea bed. Wave-mud interaction results to high wave energy dissipation and mud mass transport. This kind of wave energy dissipation, which generally is much more significant than wave dissipation due to bottom friction, should be considered in simulation of wave evolution and transformation in muddy coastal environments. This paper presents a numerical model of wave evolution and dissipation on fluid mud. For this purpose, the spectral decay of wave due to mud is implemented in SWAN (a third generation numerical model for Simulating WAves Nearshore) using a multilayered wave-mud interaction model. In this numerical model it is assumed that mud layer has a visco-elasic-plastic behavior.

A fine sediment transport modeling framework for estuary and coastal environments is developed based on simplified multiphase formulation. The model incorporates turbulence-sediment interactions in a two-equation turbulence closure and a rheology closure based on concentrated viscous suspension. The model has been demonstrated to capture the characteristics of tidal driven lutocline behavior observed at Amazon shelf and wave-supported gravity-driven mudflows observed at Po River prodelta. However, these results are obtained by specifying an averaged floe diameter that is independent of flow condition. The floc density is then calculated by a prescribed fractal dimension. In this paper, we report a new but preliminary extension of this model with a more realistic formulation of floc dynamics for steady equilibrium condition. It is found that detailed floc dynamics is sensitive to the predicted suspended mud concentration and flow rate under a steady current.

The paper presents a set of observed sounding data which shows a tendency of siltation in the access channel for a port in a shallow muddy coast. The data shows the higher siltation rate at offshore part of the channel regardless of occurrence of disturbance by the wind waves. From the data monitored for 25 hours of current and suspended sediment distributions along the channel, apparent increase in the near bottom concentration of suspended sediment were observed around the offshore region of the channel. The high concentration event might be a potential source for the higher rate of siltation in the area. The sediment transport model has been developed for the study site and simulated the sediment transport process mainly dominated by the tidal current as a preliminary work for future study of the estimation of the channel siltation volume.

A numerical cross-shore model for wave-mud interaction is presented that can be used to predict time dependent variations of fluid mud thickness and irregular wave transformation along soft mud profiles. The rheological constitutive equations of visco-elastic (VE) material are adopted for the behavior of fluid mud layer under the wave action. Spectral calculation method is used for the simulation of irregular wave transformation. The application of the numerical model at a field site shows the capability of the model to predict the wave height transformation along muddy profiles.

The coast of California is comprised of both sandy shorelines and cliffed coastline, and in many areas these features spatially coincide. In order to better understand the regional trends of change along the California coast, the U.S. Geological Survey is quantifying both sandy shoreline change and coastal cliff retreat for the state. The resulting database was used to examine the dynamics of the beach/cliff system. We found inconsistent evidence of a relationship between rates of cliff retreat and shoreline change on the spatial scale of 100-km cells. However, when the data are correlated within individual regions, a strong relationship exists between the geomorphology of the coast and the behavior of the beach/cliff system. Areas of high-relief coast show negative correlations, indicating that higher rates of cliff retreat correlate with lower rates of shoreline erosion. In contrast, low- to moderate-relief coasts show strong positive correlations.

The long-term stability of the carbonate beaches of Mauritius is the result of the net balance of the supply of carbonate sand from the coral reef environment and the loss of sand to adjacent depositional beaches and through passes in the fringing coral reef to off-reef environments. Carbonate sand is supplied from the lagoon and the balance has been tipped in the favor of losses over supply due to a range of anthropogenic factors including: historic coral harvesting for lime kilns servicing the sugar cane refining industry; removal of coral for water ski lanes; coral health degradation through a decrease in water quality; over-fishing; and creation of navigational passes. This paper presents a technique for quantifying the supply of sand from the various lagoon facies using sediment constituent analysis and hyperspectral imagery. Numerical models are used to describe the sand loss. Non-structural management recommendations are designed to reverse the long-term beach erosion trend.

The distribution and evolution of local, shoreline features was examined by repeated mapping of the shoreline using a sub-meter GPS to map Fire Island from June to December. One region of erosion or "hot spot" was documented to migrate to the west, in the direction of the net longshore transport, at a rate of 2.1 m/day and then to the east at a rate of 4.2 m/day. Another shoreline feature followed the progression of a theoretical advection/diffusion model created earlier by other investigators to predict the migration of longshore sandwaves. This feature migrated to the west at 0.83 m/day. Similar features on the barrier island migrated to the west up to 51.5 m/day while others migrated to the east at rates up to 93.1 m/day. No trends in migration rate with the wavelength of the hot spot could be found. Rates tended to range between 1 and 100 m/day.

This paper examines barrier-spit system morphodynamics on a tropical coast, located on Diogo Lopes Village-RN, northeastern Brazil. The mechanisms of growth and elongation of the coastal spit and tidal inlets from Diogo Lopes are underway to reconstruct the historical evolution and dynamics. The general situation in this area is one of very energetic tidal conditions causing nearly continuous sediment mobility along the bottom close to the coast. The region experiences high-energy, coastal and shelf parallel currents driven by combined flows due to oceanic, tidal and wave processes. Natural inlet was cretaed by overwash processes during more energetic periods. Currents measured inside a new inlet show maximum speed of 85 cm/s during ebb phase, while nearhore it can reaches 100 cm/s. This data set is important to develop a detailed understanding of this kind of barrier-spit system evolution.

Beach widths and shoreline change along Santa Barbara and Ventura Counties, California were evaluated using a 70-year record of rectified historic air photos. Beach widths have oscillated throughout the study period as opposed to narrowing as predicted by sediment supply reductions. Shoreline change rates evaluated using linear regression and end point rate analyses show differences between the wet/dry shoreline and back beach reference features. Most of these differences occurred along armored backed shorelines where the natural erosion of the back beach was halted while the wet dry shoreline continued to erode. Beach responses to single El Niño events form a predictable pattern of beach reorientation. Similar patterns of shoreline reorientation can be seen in the long-term shoreline change analyses providing evidence that El Niños may play an important role in long-term coastal evolution.

Regional sediment transport dynamics at and adjacent to the MCR were quantified using historical shoreline and bathymetry surveys. Four distinct depositional trends were identified: 1) the modern ebb shoal was deposited approximately 2-mi seaward of the natural shoal in about 90- to 130-ft water depth as a result of jetty construction; 2) the primary area of sedimentation on the ebb shoal is north of the entrance, and it continues to migrate north with time; 3) northward-directed sediment transport from the entrance has resulted in net accretion along the shoreline and on the continental shelf seaward of Long Beach Peninsula; and 4) continual shoreface erosion south of the MCR is the result of sediment diversion by the south jetty to the west and north of the entrance toward the ebb shoal and onto the continental shelf. The long-term sediment budget indicates that approximately 4.4 Mcy of sediment is transported to the continental shelf north of the MCR on an annual basis.

Regional Sediment Management (RSM) is a systems-based approach for managing multiple projects involving sediment. RSM fosters balance between infrastructure and natural system processes, resulting in reduced project costs and achievement of greater benefits. This paper introduces the RSM concept and describes how RSM is being implemented at the Mouth of the Columbia River to sustain the inlet's 100-year old navigation infrastructure and adjacent shore lands. Implementing RSM at this energetic inlet involves feeding the inlet's morphology using dredged material, and letting nature do the work of dispersing the placed dredged material to supplement the inlet's sediment budget, without compromising the reliability of the navigation channel. The paper discusses the types of data that are being collected and analyzed to understand the environmental forcing affecting the inlet's morphology. The paper also addresses how dredged material disposal is being conducted to implement RSM.

A long-term statewide beach surveying program in South Carolina has compiled a substantial record of beach and shoreface geometry across a region of diverse hydrodynamic and geologic framework. Initiated to support statewide beachfront regulatory obligations, the accumulated time-series has also afforded long-term monitoring of several beach nourishment projects and record of evolution of profile geometry in areas progressively interfacing with coastal development as well as relatively undisturbed systems on a decadal scale. Work to date has focused on the influence of underlying geologic framework on profile geometry and variability. In sediment starved areas of South Carolina's Grand Strand, profile geometry is often better defined as a series of linear segments rather than a smooth concave up form. The breaks in slope frequently reflect stratigraphic changes observed in nearshore geophysical records and cores collected in the lower beachface. The time series documents 13+ years of behavior, revealing decadal-scale changes across the full active shoreface. These changes are relevant to consideration of long term coastal evolution. Estimates of shoreline change have traditionally been defined by change in subaerial features or datums such as the wet-dry line defined on aerial photos or Mean High Water (MHW) contour. Across the state, and much of the nation's shoreline, these features are progressively encroaching on development and are being influenced by "hard" and "soft" erosion protection strategies. In practice, some sections of the South Carolina coast have been defined as stable (zero long term erosion rates) as the subaerial shoreline features have been artificially stabilized. These same areas continue to require beach nourishment and other engineering efforts to maintain beach volume and function. Profiles across the shoreface over the past 13 years in several such locations show evidence of continued migration of the lower shoreface. The resulting steepening of the beachface may be expected to modify prevailing hydrodynamics and sediment dispersal and demonstrate change in profile geometry on annual-decadal scales. Efforts to predict long term coastal behavior are traditionally been based on some variation of the Bruun Rule, which presumes migration of persistent profile geometry in the face of rising sea level. Any approximation of persistent profile geometry requires the subaerial and shoreface systems to migrate uniformly at all depths. The decoupling of the upper beach system by modifications such as groins, seawalls, and beach nourishment from the mid-to lower-shoreface suggests that profile geometry for a site may evolve not only on annual time scales, but on decadal time scales as well. Additionally, at one location experiencing substantial expansion of coastal dune fields over the past 20 years, the shoreface has continued migrating landward also resulting in a net steepening of the nearshore. Within the time series of shoreface profiles are glimpses of the incremental development of the marine unconformity surface characteristic of transgressing shorelines. The composite envelop of profile minima is locally expressed as a series of scarps into older underlying substrate with limited expression on the fair-weather sea floor. In some areas relief on the order of 0.5 meters exists which may become emergent during storm events and also influences processes and sediment dispersal. Recent efforts towards modeling morphological behavior in predicting longer term coastal evolution have shown substrate slope influences transgression rates (Stolper et al, 2005). The growing database of actual behavior across the shoreface on decadal scales may provide important verification to developing models and investigating coastal behavior on time periods longer than single "events" but shorter than "geologic time scales" evidence on the inner shelf.

We evaluate three classes of shoreline change rate methods on all sandy beaches of Maui: 1) methods that estimate shoreline change transect by transect, 2) methods that combine data from all transects to estimate shoreline change, and 3) extensions of (2) that include acceleration. Using these, we compare 50 yr hazard zones from beaches exposed to different conditions, natural beaches versus altered beaches, and well-defined littoral cells versus open systems. Acceleration methods fit the data well, but don't predict the erosion hazard zone well. Altered beaches and open system beaches are better fit by methods with acceleration at a higher proportion than natural or pocket beaches. The traditional transect by transect method that calculates shoreline change at discrete points along a beach never qualifies as the best fit model.

To assess the long-term safety of a dune-protected coastal area, models are needed for forecasting both long-term coastal evolution and dune erosion due to the occurrence of a super storm. In long-term model forecasts, however, information on dune shape is lost. Explorative calculations show that the output of the event-scale dune erosion model is quite sensitive to the dune height. For a given super storm, a higher dune leads to a larger forecasted erosion volume, but to a less land inward position of the erosion line (the line that indicates how far erosion is expected to reach land inward). Clearly, a solution should be found for adding information on realistic dune shapes to the long-term coastal evolution forecast. EOF decomposition of observed dune profiles provides simple but realistic dune shape functions that could be used to redistribute forecasted dune volumes into realistic dune shapes.

The Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system collects lidar and hyperspectral data for the U.S. Army Corps of Engineers (USACE) National Coastal Mapping Program. CHARTS is owned by the U.S. Naval Oceanographic Office and operated jointly with the USACE through the Joint Airborne Lidar Bathymetry Technical Center of Expertise. Simultaneous collection and shared geo-referencing enables fusion of the two data types into high-level information products that are used to support decision-making at USACE coastal projects. New products resulting from data fusion research currently coming online are bathymetric laser bottom reflectance images, atmospherically-corrected image mosaics, and hyperspectral final bottom images. All of these products are input for automated classification algorithms that generate physical and environmental characterizations of the coastal zone.

In North Carolina, shoreline change rates are an important component of the state's coastal management program. To enhance methods of measuring shoreline change, the NC Division of Coastal Management (DCM) is considering using mean high water (MHW) shorelines extracted from lidar data together with traditional wet/dry shorelines digitized from aerial photography. To test their compatibility, a wet/dry line and MHW shoreline derived from a concurrent 2004 oceanfront photography and lidar dataset were compared along a distance of 244 km. Results show that the MHW shoreline was seaward of the wet/dry shoreline by 2.82 m on average, and that this offset biased shoreline change rates by an average of 0.05 m/yr. The offset was greatest on low-sloping beaches experiencing higher water levels at the time of photography, but overall was small enough to suggest that the MHW shoreline can be a reliable substitute for the wet/dry shoreline.

U.S. Geological Survey (USGS) scientists used 1999 multibeam data, and 2002 lidar data collected on the inner shelf off southern California to investigate a field of (<1 m) features, termed "Rippled Scour Depressions" (RSDs). RSDs are elongate, shore-normal, and bathymetrically depressed features; their morphology was determined from multibeam and lidar bathymetry. Wavelengths of ripples seen within RSDs and on the surrounding seafloor were calculated from photography and video collected in 2004 and related to sediment samples collected in the same year. The RSDs were divided into two areas: Region I RSDs contained large (~80 cm wavelength), straight-crested ripples with coarse-grained lag, and decreased in area between 1999 and 2002; Region II RSDs were smaller, in shallower water, closer to shore, and contained shorter (~30 cm wavelength) ripples, and increased in area from 1999–2002. The RSDs did not display marked alongshore asymmetry.

The following paper describes the cross-shore and longshore seasonal intertidal beach dynamics along the macro-tidal beach of Cleveleys (UK). The studied beach is characterised by the presence of shore-parallel runnel (channels) and ridges (tabular bodies), and intersecting drainage channels. Argus video images and in-situ field measurements have been used in order to quantify the spatial and temporal variability of the complex and dynamic runnel-ridge system. In the short-term, the impact of a major storm has been analysed and correlated to the changes in intertidal bathymetry. The long-term ridge position has been determined using the Argus image contouring technique and existing beach surveys since 1991. It has been demonstrated that the frequent cross-shore ridge migration mainly occurs during high energy conditions and is governed by surf zone processes. The longshore ridges' migration occurs at larger time scales and is associated with the dynamics of intersecting or mini rip channels.

This study develops a method to identify the depth of closure using airborne laser bathymetric data, and compares the measured depth of closure with estimated depth of closures. Airborne laser data sets were collected before and after the 2004 hurricane season in southeast Florida. Estimated depth of closures in terms of wave data is compatible to the measured depth of closures. However, the estimated depth of closure is on average larger than was measured, especially in the southern end of the study area, which could be due to geologic influence. Further research is needed to determine if geology plays a critical role in the depth of closure at this study's location.

The study examines temporal and spatial changes in nearshore morphology using time-averaged images obtained by X-band radar along a 3-km long section of Cassino beach, southern Brazil. A GIS platform has been used to quantify the mean position arid magnitudes of cross-shore movements of the three nearshore bars identified on the radar images in a time period between April 15 and May 31, 2005. Analysis of the time-averaged images show that increasing wave energy results in straight bars while reducing wave energy gives rise to crescentic features. The first bar responds rapidly to changes in wave energy while the two other bars respond only to extended periods of hydrodynamic forcing and generally exhibit a lagged response time in relation to the first bar. A storm with significant wave height of 1.1 m, period of 8 s and currents reaching 1.5 m/s resulted in migration rates of about 30 m/day for the first bar and 13 m/day for the second and third bars that lasted two to four days.

Intertidal morphology was monitored continuously with an X-band radar at research pier HORS located in Hasaki, Japan facing Pacific Ocean. The horizontal extent of a radar image is approximately 5.6 km and hourly averaged radar images were processed to observe longshore distributions of shoreline and bar positions. Longshore mean shoreline and bar positions and their variation showed a seasonal change, which follows so-called beach-cycle. Wavy features with wavelength of several hundred meters were observed in shoreline locations at low energy periods, which migrated to the down-wave. Migration speeds show high correlation with the longshore current velocities measured at the pier. Wavy appearances were also observed in bar locations and their migrations are also correlated with the longshore velocities.

The application of ground-penetrating radar (GPR) to five prograding barriers around northern New Zealand has produced detailed three-dimensional morphostratigraphic models. These barriers exist within a variety of geologic settings ranging from the high-energy, sediment rich west coast to the lower-energy, sediment starved east coast. Additionally, a composite Pleistocene-Holocene barrier exists along the east coast providing the unique opportunity to study barrier evolution not only through space but time. Nearshore, beach and dune facies delineated within each barrier lithosome form regressive facies successions with differences in shoreface geometry between sites. These differences detected within the stratigraphy are reflected in the contrasting depositional settings of the west coast dissipative morphodynamic state versus the east coast intermediate morphodynamic state. The replication of this stratigraphic form along shore and over successive sea-level stands indicates that the present day barrier evolution and depositional setting is similar over various spatial and temporal settings.

A formula is proposed for the longshore sediment transport in the swash based on the study by Larson et al. on swash-zone transport and foreshore evolution. Hydrodynamics needed to predict the local transport rate were derived from ballistics theory, where both the cases with and without friction were investigated. The formula was validated with data from two experiments carried out in the Large-scale Sediment Transport Facility (LSTF) of the Coastal and Hydraulics Laboratory. In total five experimental cases were reproduced using a typical value on the transport rate coefficient from Larson et al. A simple exponential decay with distance offshore was employed to model the transition between the swash zone and the inner part of the surf zone. The LSTF data on transport rates measured in this region supported such a simplified model.

This paper discusses the effect of the longshore sediment transport in the swash zone on the evolution of the shore line. The beach evolution model presented here is based on an N-line approach including a local estimation of the sediment transport function of the local current and wave characteristics. A simple model for the longshore sediment transport in the swash zone is implemented to the beach evolution model. The erosion and the accumulation of sediments around a groin appear to be significantly influenced by the introduction of the swash sediment transport.

Bore-driven swash and swash interactions are investigated experimentally. Direct bed shear stress measurements suggest bore/swash backwash interactions act to interrupt backwash (seaward) sediment transport. Catch up and absorption causes landward directed bed shear force (enhanced by impact forces onto the bed) of a short duration that does not follow the measured flow velocity trend. A single swash interaction is likely to restrict seaward direct transport and/or suspend sediment in large volumes but not directly contribute to the landward advection of sediment. Bore-driven swash hydrodynamics for a single swash event were predicted well using a non-linear shallow water wave equation model. In the mid-swash region measured uprush bed shear stress was predicted well using the drag law estimate with constant friction factor C_f approx.0.02. A smaller or time-varying C_f is required to accurately predict measured backwash bed shear stress.

The unique dataset from SUPERTANK is analyzed to examine the upper limit of beach change in response to elevated water level caused by wave runup. Thirty SUPERTANK runs are investigated, including both erosional and accretionary wave conditions under random and monochromatic waves. The upper limit of beach change approximately equals the maximum vertical excursion of swash runup. Exceptions to this direct relationship are those with beach or dune scarps. The vertical extent of wave runup above mean water level on a non-scarped beach is approximately equal to the significant breaking wave height. Scarps substantially limit the uprush of swash motion, resulting in a much reduced maximum runup. Predictions of wave runup are not improved by including a slope-dependent surf-similarity parameter. The limit of wave runup is substantially less for monochromatic waves than for random waves, attributed to absence of low-frequency motion for monochromatic waves.

The objective is to develop a physical based wave impact driven erosion model for the dune face and fore shore morphology under extreme conditions. Both (stereo) video and in-situ measurements from a large scale dune erosion experiment are available to develop this model. Visual observations during the experiments and image intensity time stacks are used to make a first analysis of dune face slumping characteristics. Three-dimensional dune and beach morphology are reconstructed from stereo video imagery to quantify morphodynamic response. Also a preliminary investigation of the relationship between wave impact and dune face erosion is presented.

The critical width of a barrier island is defined as the smallest cross-shore dimension that minimizes net loss of sediment from the island over periods from decades to centuries. This concept is of importance for large-scale restoration of barrier islands which involves rebuilding these islands to a specified geometry. Within constraints of coastal forcing and geologic and regional characteristics at the site, islands having critical width will capture deposition of washover sediment onto the subaerial beach over the project lifetime. This study reviews previous investigations of barrier island critical width and applies a newly-developed model of barrier island migration, consolidation, and overwash to assist engineering design.

Breaching of barrier islands can adversely impact society by severing infrastructure, destroying private properties, and altering water quality in back bays and estuaries. This study provides a scheme that assesses the relative vulnerability of a barrier island to breach during storms. Dauphin Island, Alabama was selected for this study because it has a well documented history of island breaches and extensive geological and geomorphic data. To assess the vulnerability of the island, we defined several variables contributing to the risk of breaching: island geology, breaching history, and island topography and geomorphology. These variables were combined to form a breaching index (BI) value for cross island computational bins, each bin every 50 m in the alongshore direction. Results suggest the eastern section of Dauphin Island has the lowest risk of breaching with the remaining portion of the island having a moderate to high risk of breaching. Two reaches in the western section of the island were found to be particularly vulnerable due primarily to their minimal cross-sectional dimensions.

This paper introduces a time-dependent model of regional barrier island breaching for multiple openings, whether as permanent inlets or as new breaches to the same bay. The model allows an arbitrary number of breaches and is forced by tide, storm surge, and wave set up. Limitations on the hydrodynamics, hence calculated breach evolution, are those associated with the Keulegan inlet model. The model includes possible closure or limited breaching by shoaling of the breach channel by longshore transport. Capabilities of the multiple breaching model are examined through eight sensitivity tests.

The formation of a new breach through coastal barrier islands is relatively common occurrence during extreme storm events. In fact, breaching has a significant role in the development and long-term morphological evolution of natural barrier islands by providing the backbarrier with sediments that accommodate both barrier island migration and the establishment of new intertidal and subtidal habitats. However, breaches also have the potential to adversely affect adjacent bays and inlets with conditions including increased water levels, damages to buildings and infrastructure on the barrier island, and impacts to existing inlets which may experience increased shoaling or even closure in the event of a breach. This paper examines the analytical/empirical tools presently used to assess breach stability and long-term growth, and it presents preliminary results from an initial attempt to simulate these processes using a numerical morphological model.

A 2.5-year data set of beach profiles was used to examine the characteristics of berm shape and the spatial distributions of the cross-shore sediment transport rate for berm formation and erosion. The seaward distance, x, is normalized by the distance of the investigation area, X, which is from the maximum wave run-up position, x/X = 0.0, to the position where the standard deviation of the beach profile takes the lowest value seaward of the mean shoreline position, x/X = 1.0. Analysis of the data reveals that the landward sediment transport rate for the berm formation increases from x/X = 0.0 to 0.4 and reaches a constant value toward x/X = 1.0. As for berm erosion, the landward sediment transport rate peaks at x/X = 0.10 and the sediment transport rate changes in the seaward direction at x/X = 0.20. From this position, the rate decreases until x/X = 0.60.

Overwash is an important process in the evolution of barrier systems. The main aim of this paper is to present short-term measurements on sediment transport induced by overwash processes. For that purpose fieldwork campaigns were performed including measurements of oceanographic conditions, overwash flows, overwash-induced morphology variations, and sediment transport patterns. The sediment dynamics induced by overwash varied according to the washover morphology even though the tidal levels or incident energy were similar. The sediment movement inside the washover plain during an overwash event can be divided into three main stages: Stage 1 — Crest Accretion, Stage 2 — Onshore Transport, and Stage 3 — Dynamic Equilibrium. The sediment transport inside the washover lobe can be characterized by one onshore flow stage, but with variations in magnitude related to the tidal levels and breaking wave height.

Pre- and post-storm topography and aerial photography, collected in regions where new washover fans were formed, were studied to determine the extent of morphologic, vegetative and anthropogenic control on washover shape and extent. When overwash is funnelled through a gap in a dune ridge and then spreads laterally on the back barrier, decelerating and depositing sediment, it forms washover fans. Fans were shown to primarily occur at pre-existing gaps in the foredune. During overwash, these gaps, or overwash throats, widened and deepened. The shape and extent of the fan was shown to depend on not only the pre-storm topography, but also the existence of beach tracks, roads and other anthropogenic influences and vegetation. The cross-shore overwash profile change model by Larson et al. and Donnelly et al. was modified to include pre-storm throat widths and a lateral spreading angle estimated from the pre-storm topography as inputs and tested using cross-shore profiles through the fan centres. These new inputs make the model more generalised, such that the calibrated model is applicable to a wider range of cross-shore profiles.

Overwash induced by storm conditions is one mechanism causing coastline change with cross-shore erosion and deposition. Many field studies have been conducted but laboratory experiments are few. This experimental study was conducted for estimation of eroded sand volume by overwash. The experiments were conducted at two different wave heights and four different wave periods in two different slopes of beach face for regular and irregular waves. The experiments were done in a 2D wave tank on mid-scale at Texas A&M University. The measured data from 32 different tests were used to analyze the characteristics of overwash.

The shoreline changes along the backbarrier of a barrier system are extremely variable and critically dependent upon geographic location and the inherent interaction with hydrodynamic processes. There are only a few studies describing the backbarrier morphodynamic evolution and inherent implications to the entire barrier system. In the present study it is performed the classification of the major evolution and maturation trends observed at Ria Formosa backbarrier, evaluating in particular the role of the complete washover occurrence. Besides, the direct influence of inlets displacement, complete overwashes were considered to be one of the main events responsible for sediment availability at the backbarrier, and consequently interfered with the obtained evolution/maturation. Complete washover were assumed to contribute both to immature and mature backbarriers, at different time scales observation.

Ridge-like shoal topography is well developed on the continental shelves of the Mid-Atlantic Bight and the northeastern Gulf of Mexico. In both cases, these linear sand ridges are oriented parallel to the predominant wave approach direction, suggesting common processes for their evolution and maintenance. Along the coasts of tropical islands surrounded by coral reefs, spur-like features are sometimes found. The spurs consist of coral rubble made available by the die-off or destruction of coral through natural processes or anthropogenic factors. The spur features emanate from rubble fields and are aligned parallel to the predominant direction of wave attack. These features, from disparate environmental settings, owe their maintenance and evolution to crossing wave patterns that form through refraction of waves up either side of the shoal or spur features. This paper presents examples of these geomorphic forms in both settings. Existing capabilities for simulating crossing wave processes are discussed.

Two events of crescentic bar formation in La Barceloneta beach are analyzed (Mediterranean coast of Spain). They occurred on October 2003 and on December 2005, during Eastern storms with offshore root-mean-square heights between 1.5 m and 2 m, peak periods of about 9 s and angles of incidence relative to shore-normal between 15° and 30°. The final alongshore spacings are about 300 m in the first event and about 100–200 m in the second. A nonlinear morphodynamic model is then applied to La Barceloneta conditions to reproduce these two events. The model is able to simulate the final shape of the crescentic bars, reproducing the observed spacings.

The aim of this study is to compare long-term (30 yr) bar migration characteristics at two field sites on the Danish North Sea coast. One site displays systematically onshore migrating bars (Skallingen) while the bar migration at the other site (Vejers) is systematically offshore. Using cross-shore profile data and a sediment transport model, the paper discusses the mechanisms that cause divergent longshore bar behaviour at the two sites. The main reason for the difference appears to be larger undertow speeds at Vejers, caused by a steeper outer shoreface and a larger bar relief, leading to breaking wave reformation between bars.

A methodology is presented to identify possible rip current embayments from lidar-derived shorelines, along the U.S. Oregon coast. Analyses of these features include their location and their representative length scales in an effort to determine a desired orientation of the features. A total of 99 embayments were analyzed having an average length and amplitude of 575 meters and 17meters. During the major El Niño event of 1997/1998 there is an increase in size; however, the total number of embayments remained unchanged. The locations of rip embayments in the respective surveys does not show any significant correlation and appears to be random.

The inner continental shelf off northern South Carolina is a sediment-limited environment characterized by extensive hardground areas, where coastal plain strata and ancient channel-fill deposits are exposed at the sea floor. Holocene sand is concentrated in large shoals associated with active tidal inlets, an isolated shore-detached sand body, and a widespread series of low-relief sand ridges. The regional geologic framework is a strong control on the production, movement and deposition of sediment. High-resolution geologic mapping of the sea floor supports conceptual models indicative of net southwestward sediment transport along the coast.

A sand wave field in the eastern flood channel of Moriches Inlet was monitored for eight weeks during the summer of 2005. Bathymetric data show sand waves which are 15 m long and 39 cm tall with shallow slip faces. These sand waves remained stationary over the eight week study. Analysis based on work by van Rijn and Yalin suggests that these sand waves were created when the current velocity reaches 80 cm/s. However, the peak current speeds recorded during this study are less than 60 cm/s. Infrequent, high-energy events are believed to have created these sand waves. A hypothetical event creating these sand waves is described based on a linear analysis of tidal range and peak tidal currents. Water level data from Sandy Hook, NJ and Shinnecock Inlet, NY are used to identify this event. This study demonstrates that episodic events may control sand wave morphology and that once emplaced the sand waves become autonomous.

Bed forms in alluvial systems are three dimensional. The most common bed forms are: ripples, dunes and bars. Under certain flows, different bed forms may be superimposed on each other, e.g. dunes superimposed on bars or ripples superimposed on dunes. The irregularity in the bed of alluvial streams caused by the existence of bed forms produces additional flow resistance, which affects the hydrodynamics and sediment transport properties of the system. The geometry of bed forms in large alluvial, rivers such as the Lower Mississippi River exhibits both coherent and random characteristics. Average wave lengths and heights alone cannot adequately describe these bed forms. A spectral approach was used in this study to capture the periodicity and frequency distributions of the observed bed forms along a study reach in the Lower Mississippi River extending from river mile zero (Head of Passes) to river mile 234 (near Baton Rouge, LA).

Laboratory experiments were conducted in a large wave flume to study the effects transient wave conditions on ripple geometry. Two primary experiments of nine hours each were performed in which the order of two wave conditions (4m and 6m waves) was altered. Bed measurements over the region were acquired using acoustic equipment, and results of ripple equilibrium characteristics were compared.

Complex empirical orthogonal function (CEOF) analysis is applied to investigate the medium-term morphologic evolution of the ebb shoal at Sebastian inlet, using a high resolution decadal dataset of hydrographic surveys. Results indicate that most of the variance (98.2%) is found in the first complex function (SM-1) interpreted as the average bathymetry, showing no significant time-dependent fluctuation. The second function (SM-2) accounts for 0.8% of the total variance and is dominated by a cross-shore transfer between the shoreward and leeward flanks of the shoal, as well as deposition from the ebb-jet and natural bypassing around the shoal. The temporal dependence (TM-2) showed large random changes that may correspond to bypassing activities in the inlet vicinity. The CEOF technique is successful in reproducing propagating sedimentation patterns not recognized by regular EOF, such as bypassing around the leeward flanks of the shoal, and cross-shore transfer around the terminal lobe and availability for bypassing.

Deep draft ships transiting through confined channels can significantly alter surrounding hydrodynamic conditions. The Burlington Shipping Channel is a confined channel on Lake Ontario which has experienced significant scour due to ship drawdown. A range of investigations including the development of an SGH model of the Burlington Channel have been undertaken to understand the processes leading to scouring near the channel walls. It is proposed the direction of ship motion is fundamental to the depth of scour observed at the entrances to the channel. The SGH model achieved a good level of hydrodynamic calibration and an assessment of modeled scour based on spatial variation in critical sediment size is consistent with observed scour patterns. The critical sediment diameter along the channel is an order of magnitude greater than the native bed material. In the mid-sections of the channel, scour potential is generally independent of direction of ship motion and consecutive ship movements in opposite directions appear to cause minimal net sediment transport. The development of design criteria curves for channel protection using the SGH model is presented.

Bogue Banks, North Carolina is 40 kilometers (km) long and has received 6.6 million cubic meters of nourishment in the past five years. Six borrow areas of varying quality have been used ranging from fine, muddy sand in a federal dredge disposal area to coarse, shelly sand in an offshore borrow area. Composite sediment samples representing the native beach (foredune to low-tide terrace) were sampled before nourishment in June 1999 and after nourishment in November 2006. Profiles have been surveyed along the beach and combined by reach to form composite sections before and after nourishment. This paper provides representative pre/postnourishment grain-size distributions (GSDs) and composite profiles to illustrate similarities and (mostly subtle) differences between the native and nourished beaches. Despite some wide differences in GSDs, the nourished beaches and inshore morphology were generally maintained in the postnourishment profile. Additional sediment sampling and profiling are being conducted to quantify differences among the Bogue Banks projects.

One of the key elements in predicting beach fill performance is the evaluation of the "compatibility" of beach sands. Several formulations have been proposed to estimate the "compatibility" or "overfill" ratio. Most of them assume that both native and borrow sand has a log-normal grain size distribution. Log-normal distribution has long been accepted as the most adequate distribution for characterizing marine sediment samples. Furthermore, Galofre and Medina showed that for specific conditions of the marine dynamics a log-normal grain size distribution is achieved as the final equilibrium distribution of a sediment deposit. However other distributions, such as weibull or hyperbolic distributions, have also been proposed to represent sediment samples. In this paper, new field data are analyzed in order to further explore Galofre and Medina equilibrium grain size distribution hypothesis and to identify those situations in which sediment samples do not fit a log-normal distribution.

The Louisiana Department of Natural Resources (LDNR), along with the other Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) agencies, authorized a team led by DMJM Harris to design the restoration of the West Flank of Whiskey Island. Significant among the overall project objectives are: 1 Demonstrate the feasibility of using Ship Shoal sands for restoration projects. 2 Restoring the integrity of the West Flank of Whiskey Island. 3 Adding offshore sediment to Whiskey Island to increase sediment supply. A key design factor was the determination of the overfill requirements, which would determine how much material had to be removed from Ship Shoal to achieve the appropriate quantity and quality of material on the West Flank of Whiskey Island after the project had been completed and conditions stabilized. There are two primary approaches to determining the overfill factor, which are described in the United States Army Corps of Engineers (USACE) 2002 Coastal Engineering Manual (CEM). This manuscript discusses the design analysis, the decision on which approach to use, and associated results on the overfill factor chosen for this project.

Broward County relies on its beaches to attract tourists but 21 of the 24 miles of Broward beaches are defined as critically eroded. The Broward County Office of Waste and Recycling Services processed approximately 15,000 tons of glass each year and is searching for beneficial use of this material. The Broward County Beach Demonstration Project is investigating the feasibility of using recycled glass to augment the shore protection program needs, specifically in areas of higher relative erosion (hotspots). The addition of glass cullet as emergency beach fill may extend the life of the shore protection project by nourishing these areas with smaller volumes of fill. This paper details investigations performed to date including a literature review, geotechnical investigation, biological analyses, public perception research, and abiotic testing and shows that glass cullet is a viable beach compatible material.

This paper presents the analysis of the evolution of the Cancun Beach Nourishment, in Quintana Roo, México. The nourishment project was based on the analysis of four beach profile sets (1985, 1989, 2000, and 11/2005, after hurricane Wilma), high resolution satellite images, wave data and native sediment samples from Cancun Beach. After Wilma the remaining sand volume was approximately 0.5 x 106 m³, with beachwidth of only 10 to 17 m. Although the nourishment sediment volume (2.7 x 10⁶ m³) was limited by the available federal budget, the design dry beach width was estimated to be between 22 and 28 meters. After nourishment, three beach profile sets were analyzed (April, August and November 2006), as well as the associated morphodynamic state. At present, the beach profile tends to a pre-Wilma natural slope. This process is however decreasing the dry beach width to find a stable state along the beachface.

This paper describes a series of geomorphic investigations conducted to establish a long-term sediment budget and quantify sources and sinks of sediment contributing to the growth of fillet beaches and erosion of adjacent shorelines at the St. Joseph Harbor area on southeast Lake Michigan. Long-term bluff recession and lakebed erosion rates are determined for the study area. The impact of the harbor and its operations on the sediment budget are discussed.

Headland Control is a unique shoreline management technique whereby existing geomorphic features (i.e. headlands) are enhanced with large stone breakwaters and/or the breakwaters are strategically placed alongshore to create headlands. These enhanced or created shore headlands are widely spaced for economy, and the adjacent coasts are allowed to continue to erode toward an equilibrium shore position where a wide, stable, and protective sand beach becomes vegetated and forms a low dune. The final equilibrium planform is a large pocket beach whose dimensions will depend on the amount of sand that will come to reside in the evolving embayment. Headland Control is applicable to long reaches of agricultural or unmanaged shore land since protecting the entire property is very expensive per linear foot. Three sites where this method of shore management was implemented are discussed in terms of shore planform prediction, overall shore change, and storm response.

At the southern shore of Lake Biel in Mörigen, Switzerland, the sandy beach covered with reed plantations suffers strong erosion although a protection project was realized in the late 20th century. The design of this protection project included the construction of segmented porous structures (brushwood fences) parallel to the shoreline. Their purpose was to damp the incoming energy of wind-generated waves and to protect the shoreline against additional erosion. In order to enhance the shoreline protection, an additional study, based on in situ analysis of wind, waves and bathymetric evolution and numerical modeling of wave field and nearshore wave generated current responsible of sediment transport on the other hand, was carried out. The results revealed that by an adaptation of the existing system an enhancement can be achieved in order to thwart any further erosion and to promote sediment deposition at the leeside of the fences.

Goldsmith Inlet is a small semi-natural and non-navigable inlet located on the northeast shore of Long Island, NY, and it connects Goldsmith Pond to Long Island Sound. The coast is gravelly, waves relatively small because of limited fetch, and tide range relatively large at 2 m as compared to the south shore of Long Island. The inlet has been in existence since at least the 1700's, but is apparently prone to closure in recent times. Field data collection, GIS analysis of morphology, and numerical modeling of the inlet current were performed. The inlet is found to be highly flood dominant, with two natural sills restricting ebb flow. As a result, gravel remains at the inlet mouth, with the flood shoal composed of fine sand. No ebb shoal is found, probably a result of the limited ebb-tidal discharge. It is concluded that an easterly orientation promotes channel stability and is to be preferred to re-alignment of the inlet to run straight out to Long Island Sound.

The Port of Barranquilla is one of the two main Colombian Ports on the Caribbean coast. Shoaling in the Port's access channel from the mouth of the Magdalena River to the terminal of the Regional Port Society of Barranquilla has historically restricted navigation for vessels with drafts as shallow as 30 feet. The existing harbor facilities in Barranquilla will require a 40-foot deep access channel in order to allow permanent access for larger ships without navigation restrictions. A feasibility study proposed several flow training structures to scour the channel and maintain navigable access to the Port. In this study, a hydrodynamic and morphological model was constructed using the Delf3D system to test the validity of the solution defined in the feasibility study. The model was further applied to improve that solution in order to guarantee a stable navigation channel with a depth of 40 feet and a width of 150 feet as required for safe navigation. The model prediction suggests that the improved solution will create and maintain the design navigation channel within 3–4 years after construction.

The offset configuration of Tauranga tidal inlet delta system, in combination with the dredged entrance channel, hinders sediment supply to the down-drift beaches. Maintenance dredging of the entrance channel provides suitable sediment to be deposited as a nearshore berm, downdrift of the entrance channel, as a means to artificially bypass the tidal inlet and renourish the beaches of Mt Maunganui. During April and May of 2004, ~112,000 m³ of dredged medium sand was deposited between two nearshore dump grounds (Sites B and C), under the assumption that onshore transport would occur and act to renourish the beaches shoreward of these sites. Bathymetric and side-scan sonar monitoring showed erosion of the mounds at both sites and significant onshore dispersal at Site B clearly evident after disposal. Sub-aerial beach profile monitoring from 1999 to 2005 shows continued accretion of the sub-aerial beach from 2001 to 2005, partially in response to ongoing beach nourishment. This suggests that any reduction in sediment supply to the down-drift beaches is being successfully alleviated.

Estimates of maintenance dredging quantities were needed for a proposed widening and deepening of a navigation channel. However, detailed numerical modeling of sediment transport was not desired at the time. Channel sedimentation rates were estimated based on a new semi-empirical methodology. The methodology is based, on a simplification of the sediment deposition equations. Basic inputs to these equations include water velocities, total suspended sediment concentration (TSS), critical bottom shear stresses for erosion and deposition, Manning friction coefficient, bulk density of settled muds, and settling velocity for sediment particles (flocs). These equations are solved at discrete locations along the channel and integrated over time to give an overall sedimentation rate. The desktop methodology is applied to the Matagorda Ship Channel (Texas) widening and deepening project. The methodology offers a relatively simple way to estimate changes in maintenance dredging quantities for modifications to existing projects.

A mass-balance, control-volume approach is presented for estimating vertical sediment fluxes and mass-averaged settling velocities in dredge plumes. The method requires detailed measurements of velocity and suspended sediment concentration along the control volume boundaries. An example application is presented in which horizontal fluxes at the control volume boundaries are derived from Acoustic Doppler Current Profiler data. Results of the analysis demonstrate good qualitative agreement with the general understanding of sediments at the site. The control-volume method is suitable for application to other types of dredge plumes and general sediment transport research related to vertical fluxes and settling of suspended sediments.

The impact of dredging and the physical regeneration of a sand-dredging site were monitored over a period of almost seven years with side-scan sonar and multi-beam echo sounder. The seabed physically regenerated from the dredging impact within a few years, except for a limited area where multiple dredging caused a pronounced impact and the seabed remained in an altered state. Based on the observed results, questions arise regarding the meaning of the term "physical regeneration". Here I intend to propose working definitions of physical regeneration, which are dependant on the nature of the particular of investigation.

Over the past decade, the City of Norfolk, USA has financed design and construction of multiple nearshore breakwater fields and numerous beach fill projects. In 2005, an assessment of historical shoreline conditions was performed to evaluate the need for an extension of an existing breakwater field in conjunction with periodic nourishment. Based on the shoreline assessment, it was recommended that the breakwater field be extended. Three additional breakwaters at East Ocean View were designed and constructed in June 2006. Since construction, salients have formed under the local wave climate and have been maintained since construction. Periodic monitoring surveys are used to evaluate shoreline response in the vicinity of the structures and along East Ocean View beach. Monitoring will serve as the basis of design guidelines for future detached breakwater and fill placement design.

Part of the design processes in beach nourishment projects is to determine the suitability of the borrow material for placement on the native beach. Ideally the sediment would be of similar grain size distribution, shape and color. Often the borrow source is a different environment and therefore a different size distribution and predicting the amount of borrow that will remain on the profile once it is placed is problematic. Case studies on past projects indicate that fill compatibility is complex and not well predicted by using the standard suitability methods. Use of the entire grain size distribution is needed to better predict performance. Borrow material similar to the native sediment will return to a native distribution within one year, while finer or coarser distributions take longer to equilibrate. Coarser borrow material seems to provide a more stable fill. Fill volume is also important along with grain size in project success.

After more than a century of development in the field of coastal engineering and science, serious practical questions remain concerning the optimal design of coastal protection works including detached breakwaters, groins and seawalls. This paper reviews current technology applicable to coastal structure design with a critical assessment of existing and needed tools for practical applications involving sediment-structure interaction. This paper considers both functional and structural design issues and addresses the relative merits of these technologies. In this regard, it should be noted that sophisticated modeling technologies, with all of their advantages, have not yet obviated the use of empirical equations and rules of thumb in engineering practice. This is true both for design of structure plan-form arrangements (e.g., number, spacing and length of structures) as well as structure cross-section geometry (e.g., toe design, use of sacrificial toes, merits of armoring landward of a structure crest.)

On Oharai Beach, a large amount of sand has accumulated owing to the formation of a wave shelter zone of the port breakwater, causing excess deposition in the navigation channel, whereas severe beach erosion has occurred south of Oharai Port. With these large-scale beach changes, the grain size of the seabed materials has significantly changed, and the area covered with coarse sand has been expanding. Simultaneously, the catch of Japanese hard clams, the habitat of which lies in a seabed composed of fine sand, has decreased. A model for predicting the changes in contour lines and grain size was applied to Oharai Beach; the controlling effect on longshore sand transport of an artificial headland was quantitatively evaluated in terms of beach and grain size changes, and the optimum depth of the headland was determined.

The contour-line-change model was applied for predicting the beach changes around headlands on the Shimizu coast, which were built using pairs of detached breakwaters. Before constructing the headlands, there was a dynamically stable beach, at which longshore sand transport of 1.3 x 10⁵ m³/yr flowed continuously alongshore, but it was altered to a new equilibrium state, in which longshore sand transport was reduced to 7 x 10⁴ m³/yr owing to the construction of the headlands. The effect of countermeasures against beach erosion was also predicted using this model. It was found that the extension of the present detached breakwaters by 50 m in the updrift and downdrift directions to narrow the interval between the detached breakwaters is effective for reducing the necessary amount of sand nourishment by (0.5–1.0) x 10⁴ m³/yr.

Geologic maps depicting offshore sedimentary features serve many scientific and applied purposes. Such maps have been lacking, but recent computer technology and software offer promise in the capture and display of diverse marine data. Continental margins contain landforms which provide a variety of important functions and contain important sedimentary records. Some shelf areas also contain deposits regarded as potential aggregate resources. Because proper management of coastal and offshore areas is increasingly important, knowledge of the framework geology and marine processes is critical. Especially valuable are comprehensive and integrated digital databases based on high-quality information from original sources. Products of interest are GIS maps containing thematic information, such as sediment character and texture. These products are useful to scientists modeling nearshore and shelf processes as well as planners and managers. The U.S. Geological Survey is leading a national program to gather a variety of extant marine geologic data into the usSEABED database system. This provides centralized, integrated marine geologic data collected over the past 50 years. To date, over 340,000 sediment data points from the U.S. reside in usSEABED, which combines an array of physical data and analytical and descriptive information about the sea floor and are available to the marine community through three USGS data reports for the Atlantic, Gulf of Mexico, and Pacific published in 2006, and the project web sites: (http://woodshole.er.usg s.gov/project-pages/aggregates/ and http://walrus.wr.usgs.gov/usseabed/)

The U.S. Geological Survey (USGS) has been involved in geological mapping of the sea floor for the past thirty years. Early geophysical and acoustic mapping efforts using GLORIA (Geologic LOng Range Inclined ASDIC) a long-range sidescan-sonar system, provided broad-scale imagery of deep waters within the U.S. Exclusive Economic Zone (EEZ). In the early 1990's, research emphasis shifted from deep- to shallow-water environments to address pertinent coastal research and resource management issues. Use of shallow-water, high-resolution geophysical systems has enhanced our understanding of the processes shaping shallow marine environments. However, research within these shallow-water environments continues to present technological challenges.

The beaches of the Santa Barbara Littoral Cell, which are narrow as a result of either natural and/or anthropogenic factors, may benefit from nourishment. Sand compatibility is fundamental to beach nourishment success and grain size is the parameter often used to evaluate equivalence. Only after understanding which sand sizes naturally compose beaches in a specific cell, especially the smallest size that remains on the beach, can the potential compatibility of source areas, such as offshore borrow sites, be accurately assessed. This study examines sediments on the beach and in the nearshore (5–20m depth) for the entire Santa Barbara Littoral Cell east of Point Conception. A digital bed sediment camera, the Eyeball©, and spatial autocorrelation technique were used to determine sediment grain size. Here we report on whether nearshore sediments are comparable and compatible with beach sands of the Santa Barbara Littoral Cell.

Appropriate protocols are required for selection of beach-compatible sediments from offshore borrows. Determination of what constitutes ‘native' beach sand can be problematic where prior renourishment modifies true native beach sediments. Because borrow sands must at some level approximate ‘native beach sediments,' offshore exploration methodologies need to efficiently differentiate bottom sediments into usable and non-usable categories. Sand search models (SSMs) are one approach where exploration protocols are based on literature searches and geophysical-geotechnical techniques that are conditioned by regional geomorphology, sediment dynamics, sedimentary properties, seismostratigraphy (calibrated with vibracores), and deposit morphologies (including facies recognition). Engineering-environmental performance guides attempts to ‘match' borrow sediments with existing beach sands, but exact matches always may not be found in offshore materials. This guidance is, in large part, a balancing act that attempts to replicate beach stability and biological beach performance where trade offs are inevitable.