CMS-Flow is a coupled time-dependent circulation, sediment transport and morphodynamic model based on the numerical solution of the mass, momentum and transport equations on a Cartesian (quad-tree) grid network with both explicit and implicit solvers. It has been developed and is currently supported under the Coastal Inlets Research Program (CIRP) conducted at the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL). The model's primary function is to support multi-disciplinary research teams and conduct practical projects at coastal inlets. CMS-Flow has been designed with a relatively simple code structure which allows for rapid development and inclusion of new sediment transport algorithms, while always being accessible to the general modeling community, including both USACE and commercial users. Today, CMS-Flow is an integral component of the CIRP, providing technology for simulating hydrodynamics, waves, sediment transport and morphology for short and long timeframes in coastal inlets, adjacent beaches, navigation channels and bays.

The Coastal Inlets Research Program (CIRP) of the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL) has developed a nearshore spectral wave transformation numerical model to address needs of the U.S. Army Corps of Engineers (USACE) navigation projects. The model is called CMS-Wave and is part of Coastal Modeling System (CMS) for wave estimates in the vicinity of coastal and estuarine navigation channels. It can simulate important wave processes at coastal inlets including wave diffraction, refraction, reflection, wave breaking and dissipation mechanisms, wave-current interaction, and wave generation and growth. This paper describes recent improvements in CMS-Wave that include semi-empirical estimates of wave run-up and overtopping, nonlinear wave-wave interactions, and wave dissipation over muddy bottoms. CMS-Wave may be used with nested grids and variable rectangular cells in a rapid mode to assimilate full-plane wave generation for circulation and sediment transport models. A brief description of these recent capabilities is provided.

An implicit finite volume scheme is developed to solve the depth-averaged 2-D shallow water flow equations. The computational mesh consists of rectangular cells, with quadtree technology incorporated to locally refine the mesh around structures of interest or where the topography and/or flow properties change sharply. The grid nodes are numbered by means of an unstructured index system for more flexibility. The governing equations are solved using the SIMPLEC algorithm on non-staggered grid to handle the coupling of water level and velocity. In this non-staggered system, primary variables u-, v-velocity, and water level are stored on the same set of grid points, and fluxes at cell faces are determined using the Rhie and Chow's momentum interpolation method to avoid spurious checkerboard oscillations. The discretized algebraic equations are solved iteratively using the GMRES method. The model has been tested against measurement data for steady flow around a spur-dyke in a laboratory flume and tidal flows in Gironde Estuary, France and Grays Harbor, USA. The model reasonably well reproduces the temporal and spatial variations of water level and current speed observed in the measurements. The laboratory test has demonstrated that the quadtree mesh is cost-effective, while the two field cases have shown that the model is very stable and handles wetting and drying efficiently.

Robust and reliable formulas for predicting bed load and suspended load were developed for application in the nearshore zone where waves and currents may transport sediment separately or in combination. Also, a routine was included to determine the sediment transport in the swash zone, both in the longshore and cross-shore directions. An important objective of the development was to arrive at general sediment transport formulas suitable for a wide range of hydrodynamic, sedimentologic, and morphologic conditions that prevail around coastal inlets. Thus, the formulas yield transport rates under waves and currents, including the effects of breaking waves, wave asymmetry, and phase lag between fluid and sediment velocity for varying bed conditions. Different components of the formulas were previously validated with a large data set on transport under waves and currents, and in the present paper additional comparisons are provided for the complete formulas using data on longshore and cross-shore sediment transport from the laboratory and the field, encompassing the offshore, surf, and swash zones. The predictive capability of the new formulas is the overall highest among a number of existing formulas that were investigated. The complete set of formulas presented in the paper is collectively denoted the Lund-CIRP model.

This paper presents a depth-averaged sediment transport model with emphasis on morphodynamic processes near coastal inlets and navigation channels. The model solves the depth-averaged two-dimensional non-equilibrium transport equation of total-load sediment, considering bed-material hiding and exposure, avalanching and sediment transport over hard bottoms. The model is coupled with a depth-averaged circulation model and a spectral wave transformation model. Predicted bed changes are compared with measurements for two laboratory experiments of channel infilling and in a field study at Shinnecock Inlet, Long Island, NY. The results indicate that the model is capable of predicting the general trends of morphology change and provides a useful tool for engineering applications such as coastal sediment management, navigation channel maintenance, and beach erosion protection.

The Coastal Modeling System (CMS), developed by the US Army Engineer Research and Development Center's (ERDC) Coastal Inlets Research Program (CIRP), is applied to model morphology change at a dual-inlet system, the Johns Pass and Blind Pass system in West-Central Florida. The CMS combines computation of current, wave, and sediment transport, leading to the prediction of morphology change at tidal inlets and the surrounding beaches. Medium-term CMS runs, with simulated times of 1.2 to 1.6 years, were completed and compared with extensive field data. Stronger tidal flow through the dominating Johns Pass and weaker flow through the secondary Blind Pass were calculated, indicating that the model reproduced an essential aspect of this interactive two-inlet system. The complicated wave refraction and breaking over the ebb tidal deltas and along the adjacent shorelines were accurately modeled, leading to a realistic representation of the wave-current interaction. Wave-breaking induced elevated sediment suspension and transport were described by the model. The predicted morphology change agreed well with field data. The CMS captured several key spatial trends of morphology change, e.g., erosion along the downdrift beach and accretion at the attachment point. The computed 32,000 m³/yr sedimentation volume in the dredge pit at the updrift side of Blind Pass matched the measured value of 35,000 m³/yr with a similar spatial distribution pattern, suggesting that the calculated net longshore sediment transport rates are accurate. The computed sedimentation rate of 60,000 m³/yr at a designed dredge pit on Johns Pass ebb-delta agrees with the generally accepted gross longshore transport rate. Rapid and large morphology change in response to high wave-energy events is predicted and is consistent with field observations.

Fire Island, New York, is a 50-kilometer-long barrier island that has remained positionally stable without any formation of breach inlets for nearly 200 years. Some researchers have attributed its stability to a major supply of sand moving onshore from relatively deep water (i.e., >10 m depths). Others have demonstrated via sediment budgets that the principal sand sources at decadal to century time scales are littoral sediments derived from eroding beaches, bluffs, and cannibalization of inlet shoals in shallower depths (i.e., ≤10 m). Published sediment budgets indicate that the quantity in question is of the order 10⁵ m³/yr. The possibility that this deep-water source of sand is significant, active, and persistent at decadal to century time scales has led to reluctance to mine deep-water shoals for beach nourishment of Fire Island. Herein, the authors review five factors related to the potential for a significant deep-water sand source in this setting: (1) spatial and temporal frames of reference necessary for this flux of sand; (2) studies of scour and sediment transport over offshore features; (3) sediment size distribution across the foreshore; (4) depth of closure (DOC); and (5) contribution of abandoned inlet shoals. The authors conclude that evidence for an onshore flux of sediment (i.e., order of 10⁵ m³/yr) is lacking and suggest that reluctance to mine the offshore for beach nourishment is unfounded.

A model and field investigation of hydrodynamic processes and morphological change at a sand-substrate tidal inlet is presented in order to describe conditions that can lead to shoaling and channel constriction. The Coastal Modeling System (CMS) developed at the Coastal and Hydraulics Laboratory of the U.S. Army Engineer Research and Development Center (ERDC) employs a depth-integrated two-dimensional circulation and sediment transport model, CMS-Flow, coupled with a phase-averaging, steady-state wave model, CMS-Wave, to simulate hydrodynamics and morphodynamics at Moriches Inlet in Long Island, New York. Short-term model simulations were conducted with measured water surface elevation and time-varying wave forcing to examine the capability of the model to simulate storm versus typical forcing. Model calibration and verification was performed by comparing calculations to measured water surface elevation and current velocity data collected during a field study at Moriches Inlet in 2004. Shoal development and relative movement of morphological features were reproduced in the model simulations. During simulated storm conditions, a vortex with a weak velocity field off the tip of the east jetty caused sediment to accumulate on the eastern boundary of the inlet channel. The alignment of the channel prevents the shoal from being scoured clear of the jetty. These modeled results were verified by observed morphologic response of Moriches Inlet to extratropical storms consisting of shoaling and channel constriction along the flank of the entrance channel and inlet throat. A 14-month long-term simulation also reproduced observations of channel infilling on the outer channel and accretion on the ebb tidal delta.

Packery Channel is an artificial inlet that occupies a historic ephemeral pathway between Corpus Christi Bay and the Gulf of Mexico. In 2005, the inlet was opened by Hurricane Emily during its construction and has remained open and navigable for more than 4 years. The shallow-draft channel has not required maintenance dredging despite episodic shoaling during storms, including Hurricane Ike. Stability of the inlet and adjacent beach is attributed to location in the southeast corner of Corpus Christi Bay, receiving augmented ebb flow by wind setup accompanying winter fronts. The ebb current, with speed sometimes exceeding 1.0 m/s, scours sediment deposited during the summer months, thereby maintaining channel depth adequate for water exchange and navigation. After the channel opened, a deposition basin initially served as the main sediment repository for sediment scoured from the bay side. Entrance channel shoaling began to increase in 2008, initiated by 15,000 m³of beach sand that entered the channel during Hurricane Ike. Subsequent shoaling is attributed to unrestricted wind-blown transport enhanced by drought. Since completion of the 430-m long dual jetties in 2006, an ebb-tidal delta has not formed. Ebb delta development is suppressed by a strong longshore current and longshore bar formation that alternates in direction seasonally, and by strong bursts of ebb flow during winter. The inlet is located in a region of nearly balanced longshore sediment transport, indicated by near-symmetric shoreline response at each jetty. The shoreline within a 1-km zone of the inlet advanced at a rate of 7.5 m/yr, whereas along the 18-km monitoring area it receded at a rate of 1.6 m/yr, reflecting in part the influence of Hurricane Ike. Channel performance tracks closely with that reported in the original design, with stability to date exceeding those 1997 predictions.

Shark River Inlet, located on the north New Jersey coast, is served by a federal navigation channel that has until recently required little maintenance dredging. Although possessing a small estuary, the inlet is hydraulically efficient because of the small width to depth ratio of its entrance that is stabilized by parallel jetties. After placement of approximately 4.8 million m³ of beach nourishment to the north and south of the inlet as part of an erosion-control project conducted in the late 1990s, inlet maintenance increased beyond that anticipated. Analysis of channel and nearshore surveys indicates that an ebb-tidal delta is forming where none had existed previously, attributed to the recent availability of sand from the beach nourishment and a lack of sand prior to that construction. Jetty tip shoals also encroach on the channel, dependent on season, with longshore transport directed primarily to the north during summer (the predominant direction of transport) and to the south during winter. Formation of the ebb delta must be accounted for in the sand budget of the adjacent beaches. After conducting a GIS analysis of ebb delta growth to understand geomorphic trends, the Coastal Modeling System (CMS) was established to numerically simulate waves, current, sand transport, and morphology change. The CMS reproduced observed trends in ebb-delta growth, and multi-year simulations indicate the time scale of approach to dynamic equilibrium of the ebb delta and establishment of natural sand bypassing at the inlet.

Georgica Pond, on Long Island's ocean coast in East Hampton, NY, is normally separated from the ocean by a beach about 100 m wide, but mechanically opened to the Atlantic Ocean. Observations of the breach were made for three days, until it closed naturally. A channel 6 m wide was dug on April 23, 2008. The water level in the Pond was initially 1.46 m higher than the ocean. Upon completion of the channel, pond water rushed seaward through the new inlet at a speed reaching 3.7 m/sec. The flow was supercritical with a hydraulic jump forming at the inlet mouth. The cut widened in an hour by the progressive, sudden collapse of steep sections of bank along its length, growing at a rate of about 0.2 m/min, then slowing to about 0.1 m/min, eventually stabilizing at a width of 43 m. Forty-two hours after opening, the salinity in the pond suddenly jumped from 7 to 19. Pond salinity reached 26 about four days after the inlet opened. Over the course of five days, the water level in the pond fell 0.5 m, draining 530,000 m³ of water into the ocean. About 3,800 m³ of sand formed an ephemeral ebb shoal that was gradually swept to the west and back into the western beaches by wave-induced longshore transport. The inlet closed by April 28. On May 2, 8.5 days after the opening, salinity dropped to 13 and continued to fall slowly as freshwater drained into the pond.

This paper reviews the 25-plus year history of significant developments of the GENESIS shoreline response model. Topics discussed are line sources and sinks of sand, representation of shore-normal structures including natural sand bypassing, wave transmission by and shoreline response to shore-parallel structures, seawalls, migrating longshore sand waves, seasonal variation by cross-shore sand transport, sand transport due to tidal and wind-generated currents, preservation of the regional shape of the shoreline, and the interaction between the beach berm and the dunes behind it. Such developments have been done in a consistent way, based on thorough literature reviews, beta testing, comparison to beach behavior, and quality control. The challenges have been not only to represent the features themselves, but to be consistent to the basic assumptions of shoreline modeling theory. Through these added capabilities, GENESIS has evolved to meet the challenges of modern, multi-scale, long-term coastal engineering applications.

This paper describes a methodology for modeling long-term evolution of multiple inlet systems in southwest and central Florida. The paper discusses the application of this methodology to two inlets within Sarasota Bay system in southwest Florida. The case studies of Longboat Pass and Venice Inlet demonstrate the importance of considering large temporal and spatial scales in multiple inlet systems. The results describe the evolution of Longboat Pass and Venice Inlet from 1880 to present. The analysis begins with natural conditions that existed before dredging or inlet modifications and investigates how inlet evolution can be influenced by navigation improvements or mining of ebb shoals for beach nourishment.

The influences of tide and water level rise on the cyclic medium-term seaward bar migration were examined using a one-dimensional numerical model of beach profile change, in which the cross-shore sediment transport rate was assumed to consist of four contributions due to sediment suspension and undertow, velocity skewness, velocity atiltness and beach slope. The model was calibrated with a year-long dataset of beach profiles obtained at the Hasaki coast of Japan in 1989, when the duration of medium-term seaward bar migration was approximately 1 year. The comparison between bar crest positions predicted with and without the tide at Hasaki during a two-year period including the calibration period of 1989 and the following year shows that the bar migrated further seaward without the tide than with the tide. The comparison between bar crest positions during the two-year period predicted with the tide and the water levels 0.5 m higher indicates that the bar crest positions were located further seaward with the higher water levels than with the tide in 1989. The difference between cyclic medium-term seaward bar migrations with and without the tide, and that with the tide and the higher water levels, are attributed to wave breaking on and seaward of the bar crests.

The shoreline stabilization adjacent to the public access boat ramp in the Packery Channel basin has been damaged in two separate events. For the shoreline damage at the boat ramp bulkhead, toe scour is the likely mechanism for failure. Typical sources of hydrodynamic forcing that can lead to toe erosion include storm currents, locally generated storm waves, and offshore storm waves propagating into the basin through Packery Channel. Quantitative analysis of storm induced wind generated waves and currents eliminated them as possible causes of the damage. However, photographic and movie evidence indicate the presence of low-frequency low-amplitude waves propagated into the basin and impacted the boat ramp. The Coastal System Model (CMS) was used to simulate a range of these low-frequency low-amplitude waves and the results demonstrated that these waves could produce sufficient flows in the vicinity of the boat ramp shoreline to cause the damage. Subsequent modeling was used to develop design criteria for additional shoreline stabilization.

Coastal barrier islands are natural lines of defense and an integral part of a comprehensive flood risk reduction and management plan. A high resolution numerical modeling system capable of representing complicated coastal landscapes and simulating all the primary relevant physical processes is applied to better understand the influence of barrier island restoration on hurricane surge propagation. Model results indicate that barrier island restoration may significantly alter surge pathways and flood volumes of surge reaching inland coastal areas as open water passes become the dominant flow mechanism during a storm event. However, the exclusion of the morphologic evolution of a barrier island during a storm's passage is a significant limitation with the existing numerical models and is currently under development. The results in this paper demonstrate the need to include morphologic changes to fully evaluate the impact barrier islands have on water levels at the mainland coast.

Direct measurements of coarse sediment (gravel) transport were obtained over an interval of 14 months from a mixed sand and gravel beach on Bainbridge Island, Puget Sound, WA in order to quantify the relative role of different forcing mechanisms and the corresponding time scales of morphological response. The measurements were applied to validate a system of integrated numerical models that includes: a tidal circulation model, a wind-wave growth and transformation model, a vessel wake model and a one-dimensional, profile-based model. The latter model, which provides a long-term integrated assessment of the beach response to major forcing mechanisms, was the primary tool for investigating the impacts of tides, waves and wakes on the mixed sand and gravel shores of the study area.

Radio Frequency Identification (RFID) Passive Integrated Transponder (PIT) technology was implemented in tracking studies of gravel-sized sediment particles, and complemented the beach profile surveys and meteorological and hydrodynamic measurements. The sampling of the gravel tracers provides sufficient resolution to reveal the seasonal transport patterns, which include a range of wave and vessel wake climates. Simulations of cumulative transport rate predicted with the integrated modeling system compare well with the alongshore tracer movements and capture the dominant trends and variations during the time period of the measurements. The measurements and modeling reveal that the transport is dominated by wind waves in an alongshore uni-directional process that occurs mainly in winter. However, beach response is also controlled by site-specific exposure to prevailing winds and car ferry wakes. In non-storm intervals, transport is brought about by the combination of vessel wakes and tidal currents; the sub-critical car ferry wakes provide a mechanism for post-storm recovery, in this low energy restricted fetch environment.

Tróia peninsula, located on the western coast of Portugal, is undergoing tourism development, including construction of a marina. The marina basin was created by dredging a coastal stretch on the northern terminus of the peninsula on the estuarine side, making available beach-quality sediment for nourishment. A study was carried out to identify potential applications and opportunities to place the dredged sand in a beneficial manner. Many variables were considered in the study design in incorporating pre-project beach profile surveys and sediment sampling. Beach-fill design and placement procedures were proposed according to the purpose and constraints of the particular site, while recognizing the implications of the nourishment in a regional sediment management context. Between October 2006 and March 2007, 286,000 m³ of sand was placed along four beach sectors with a total alongshore extent of 1,700 m in the vicinity of the new marina and the Tróia Roman Ruins archeological site. The emplacements included dune, beach berm, and beach face nourishment, providing restoration of beaches and dunes and also increased buffering capacity in an area of damage to cultural resources of the peninsula. A monitoring program was deployed to assess performance and impacts of the nourishment on adjacent areas, and to identify problems and their causes. The surveys of August 2007 indicate that a significant part of the emplaced sand had been mobilized alongshore promoting the spreading of the fill material to down-drift areas while inducing a general reduction in the beach face slope, and attaining a more natural beach profile.

Westhampton Beach is located on the barrier island between Moriches Inlet and Shinnecock Inlet, along the south shore of Long Island, New York. This vulnerable area has been subject to a number of beach erosion control measures under the authority of the Fire Island to Montauk Point, New York Beach Erosion and Hurricane Protection (FIMP) project as well as the related Westhampton Interim Project The Westhampton Interim Project, initiated in 1996, provided for beachfill placement, dune construction west of the groin field, periodic beachfill renourishment until 2027, and a tapering of the groins at the western edge of the groin field in order to provide a smooth transition to the downdrift barrier beaches. Project coastal processes monitoring since 1996 has shown that the shoreline position in the project area has been stable and there has been volumetric growth of the dune field west of the groin field. The 10-year average volumetric loss in the project area of 180,000 cubic yards per year is very similar to the 759,000 cubic yards (190,000 cubic yards per year) renourishment volume placed in 2005 after a four-year renourishment cycle. The largest rate of dune growth west of the groin field from initial construction to February 2009 is approximately 2.0 cy/ft-yr while the average rate of growth is 1.25 cy/ft-yr. Good stewardship of the beach and dune system will allow the Westhampton Interim Project to be maintained and provide the storm damage reduction purposes for which it was designed.

Reconnaissance studies conducted in the 1960's and 1970's by the U.S. Army Coastal Engineering Center showed that most of the sand available in Federal waters occurs in discrete linear sand shoals or in fields of several sand ridges. A geological model of continental shelf sand ridges can be combined with a numerical model of physical processes to assess the potential for recovering beach quality sand and to assess potential risks of borrow excavation. The shelf sand ridge geological model includes a coarsening upward sequence beginning with silts, clay and silty fine sand grading upward into relatively coarse sands having minimal silt and clay fraction. The upper meter of the sequence includes a clean cross-bedded sand unit that is reworked by episodic storms and waves on the inner to mid-continental shelf. The Coastal Modeling System (CMS) was applied in a series of four regional model grids positioned offshore of northeast Florida where substantial sand resources can be found. Results of a numerical model investigation of modern sand ridges of northeast Florida are consistent with the elements of the geological model. Sand ridge crests at relatively shallow depths are reworked by passing storms are predicted to be subject to topographic change of up to 1 m consisting of both deposition and erosion. The models were also applied to determine the potential influence of borrow cuts within these features on wave transformation and the potential for the modified wave field to measurably influence sand transport and topographic evolution at the shoreline.

An experimental shoreline protection project in Jefferson County, TX was constructed and monitored as part of the National Shoreline Erosion Control Development and Demonstration Program. The project determined the effectiveness of a nontraditional, low volume beach fill at reducing erosion of underlying clay layers and evaluated the performance of a clay core dune compared with that of a sand filled dune. Four cells were constructed on the beach face having 0.18 or 0.25 mm sand and fill volumes of 6 or 12 cy/ft. A fifth control cell had no fill. A 2500 ft long dune was constructed, with half being composed entirely of sand and half being composed of a clay core and sand cap. The project was constructed during the summer of 2004 and was impacted by Hurricane Ivan in September 2004 and later by the same storm as Tropical Storm Ivan in October 2004. An evaluation of profiles and other data taken before, between, and after these storms shows that the clay core dune survived the storms much more intact than the dune constructed entirely of sand. The clay core dune suffered minor scarping at its seaward toe, while up to the seaward half of the sand dune was removed in some sections. The results of the low volume beach fill were also promising. The fill performed well by protecting the underlying clay layer from erosion, but interpretation of the results is complicated by the presence of geotextile tube groins that were placed to contain the fill.

This field study identifies the short-term (hours) effect of freshly deposited wrack on aeolian transport and surface elevation changes on the backshore and foredune of a barrier island at Avalon, New Jersey, USA. Storm wave uprush reached the dune toe on 21 October 2008 and deposited a line of vegetative wrack about 2 m wide (cross-shore) and 70 mm high near the dune toe (upper wrack) and a line about 0.3–0.5 m wide and 30 mm high about 5 m from the dune toe (lower wrack). Fourteen cylindrical sediment traps were deployed 23 October 2008 when the wind blew onshore at an angle of 8 deg to the trend of the dune. Wind speed at 1 m elevation at the dune toe averaged 6.3 m s⁻¹. The lower wrack line was nearly covered with sand about an hour after initiation of transport, diminishing its effect as a barrier to cross-shore transport. The upper wrack line caused greater reduction in trapping rates, with downwind traps collecting only 3.2% and 12.7% of upwind amounts. Data from erosion pins revealed the greatest scour just landward of the lower wrack line. More sand accumulated at the upper wrack line than within other cross-shore zones. The wrack low on the beach influences sand transport rate for a limited time and is readily removed by storm waves, whereas the uppermost wrack line lasts longer, traps more sand, influences the sediment budget of the existing foredune more directly, and forms the basis of the new foredune crest.

The climate variability, its implication in coastal processses and the uncertainty that it therefore introduces in the morphological evolution of the coast are addressed. Historical evidences in the Iberian Peninsula allow relating the occurrence of significant variations in sea level position during the Holocene and its effect on the morphology, to natural climate changes. It is still unknown the way that long term climate variability will affect sea level position and the severity of other meteorological agents, which is a source of uncertainty that adds to the stochastic nature of coastal long term proccesses. In a decadal scale, under the assumption that sea level and other parameters that describe the climatic forcing remain stationary, the methodology by Baquerizo and Losada (2008) is used to predict the impact of the construction of a reservoir in the delta of the river Guadalfeo (Spain) and to illustrate how to deal with the uncertainties of the prediction for management purposes. Among other results, it is found that the probability that the shore retreats more than 120 m at any location is about 0.95, which allow to conclude that the construction of the dam will have a severe impact.

An environmentally sound concept of maximizing the benefits of the Mississippi River sediment load is proposed by allowing the river to naturally change its course to the Atchafalaya while maintaining navigation and flood control in the present channel of the Mississippi. A sediment lean, minimum necessary flow is determined for the lower Mississippi River to insure navigation and freshwater needs. Some of the political and economic ramifications are anticipated and discussed. The need for a new engineering study is addressed. Finding an effective way to utilize the sediment load of the Mississippi River is essential if the coastal wetland ecology of southern Louisiana is to survive and flourish. Allowing the river to naturally change its course is ultimately the only viable option. The short comings of other means of using the river sediment load are discussed.

A detailed feasibility study was performed to evaluate mining and transporting sand from the Mississippi River to restore Scofield Island, a rapidly-deteriorating barrier island in Plaquemines Parish, Louisiana. The proposed ecosystem restoration project includes reconstructing the beach and dune overtop the remaining island framework and closing existing breaches with riverine sand; and utilizing mixed sediments from an offshore mixed sediment source to construct a back-barrier marsh platform to create and sustain natural resource habitats and serve as the rollover platform for overwash sand. Studied and evaluated were the sand sources in the Mississippi River; methods for excavating and transporting the sand to Scofield Island; conveyance corridors from the river to the island; potential environmental and socioeconomic impacts; and estimated costs for various combinations of the aforementioned. Evaluation of eight alternative combinations of sand sources, excavation methods, and conveyance corridors on the basis of sixteen controlling factors and impact issues resulted in the recommendation of two riverine borrow areas and one conveyance corridor along an existing navigation waterway.

The successful enhancement and restoration of coastal lagoons requires a comprehensive understanding of the physical and biological conditions in each lagoon and the processes that influence the lagoon's performance. Since lagoons differ substantially from one location to another, the problems that affect lagoon performance differ as well. Coastal lagoons in Southern California (Figure 1) tend to be small with surface areas of a few hundred hectares or less and mean water depths of less than 2m. Careful monitoring studies of lagoons, together with historical reviews and data from previous studies, enable wetland scientists to recommend successful, cost-effective, environmentally sound plans for enhancement and restoration of Southern California lagoons.

Recent understanding of the settings and physical processes controlling lagoon performance will enable us to produce improved schemes to enhance these systems. Usually the biological performance of a wetland depends on improvement of the physical parameters, such as tidal flushing, water quality, freshwater flow reduction, and channel and basin sedimentation. Other factors that should be taken into consideration are the impacts of the wetland on adjacent beaches, the response of the wetland to dry and wet periods, any possible or expected future climate changes, and biodiversity management.

This paper discusses cases of environmental impacts on selected Southern California lagoons, together with proposed or existing projects to reduce or mitigate these impacts.

This study evaluated the potential increase in shoaling and associated sources of sediment as a result of proposed channel improvements for the Houma Navigation Channel in the vicinity of Cat Island Pass, Louisiana. Using morphologic change data and historical maintenance dredging rates, historical and forecasted with-deepening sediment budgets were developed. Conclusions from this study were that deepening the channel from 5.5 m to 6.1 m relative to Mean Low Gulf, a local low water datum, would increase the shoaling rate from the present 191,000 m³/year to 220,000 m³/year, and the likely source of shoaling would be sediment that is presently bypassed naturally. It was recommended that all environmentally-acceptable sediment dredged from Cat Island Pass be placed on the downdrift barrier island, East Island, part of the Isle Dernieres barrier island system. Clays and silts should be placed on the bayside of the island and sand similar to or coarser than the existing beach sand should be placed downdrift of the nodal zone on the Gulf side of East Island. Historically, sediment dredged from Cat Island Pass has been placed in designated dredged material disposal sites located 760 m west of the channel. Based on morphologic change in the region from 1980 to 2006, it appears that sediment may be transported from this placement site to deposit back into the channel. It is recommended that, if sediment cannot be placed on either East Island or Timbalier Island, that the dredged material disposal site be moved further to the west, away from the channel. Finally, based on movement of Timbalier Island and Cat Island Pass over the past 100 years, it is recommended that the channel be moved further to the west to avoid future impingement by Timbalier Island. Based on the results of this and other studies of the Houma Navigation Channel, channel realignment was approved in 2009, and authorization of the deepened channel is being requested during 2010.

This paper gives a detailed description of the Wheeler North Reef at San Clemente, CA. The reef was designed to grow and sustain giant kelp and the associated ecological community. This reef is the largest human-made reef constructed in the United States (70.60 ha, or 174.4 acres). It was constructed in two phases. The Phase 1 Experimental Reef, with a 9.06 ha (22.4 acres) seafloor footprint, was built between 18 August 1999 and 29 September 1999 (35 construction days). The Phase 1 reef consists of 56 modules, sized at 40 m by 40 m, with various hard substrate coverage densities (low, medium, high). The experimental reef was monitored from 1999 to 2005 to assess its performance. The Phase 2 design was based on the results of the monitoring program. Phase 2 construction began on 9 June 2008 and was completed on 11 September 2008 (73 construction days) adding 61.53 ha (152 acres) of reef substrate. The Phase 2 reef consists of 17 polygons varying in area between 0.56 ha (1.4 acres) and 15.74 ha (38.9 acres). The profile of the reef is a single rock layer rising no more than 0.5 m off the existing sand seafloor. This rock configuration was used because previous studies had determined that kelp in the area is most persistent on very low-profile natural outcroppings. The seafloor sand thickness was specified to be no more than 0.5 m with a hard sub-bottom to reduce the probability of the rocks being buried over time.

The impact of opening a new inlet to connect the Delaware Bay with adjacent wetlands is described. A hydraulic and stability analysis of the new inlet is presented. The growth of the ebb tidal shoal is identified as the primary cause of beach erosion updrift and downdrift of the new inlet. An estimate of the expected erosion along adjacent beaches is made and compared with erosion occurring during the period between 1994 and 2006.

We report the results of field experiments designed to compare four types of aeolian saltation sensors: the Safire; the Wenglor® Particle Counter; the Miniphone; and the Buzzer Disc. Sets of sensors were deployed in tight spatial arrays and sampled at rates as fast as 20 kHz. In two of the three trials, the data from the sensors are compared to data obtained from sand traps. The Miniphone and the Buzzer Disc, based on microphone and piezoelectric technologies, respectively, produced grain impact counts comparable to those derived from the trap data. The Safire and the Wenglor® Particle Counter produce count rates that were an order of magnitude too slow. Safires undercount because of their large momentum threshold and because its signal is saturated at relatively slow transport rates. We conclude that the Miniphone and the Buzzer Disc are appropriate for deployment as grain counters because their small size allows them to be installed in closely-spaced sets.