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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., Published in the Journal of Coastal Research, Special Issue n59 p61-75, 2011. Prepared in cooperation with Coastal Science & Engineering, Inc., Columbia, SC. Sponsored in part by the Coastal Inlets Research Program of the U.S. Army Engineer Research and Development Center.

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., Published in the Journal of Coastal Research, Special Issue n59 p49-60, 2011. Sponsored in part by Pinellas County, Florida. Prepared in cooperation with the Department of Geology, University of South Florida, Tampa, FL.

A depth-averaged 2-D model has been developed for simulating coastal barrier breaching processes. The model solves the generalized shallow water equations and the non-equilibrium sediment transport and bed change equations in a coupled fashion using an explicit finite volume method on a rectangular grid. It considers interactions among transient flow, strong sediment transport, and rapid bed change by including bed change and variable flow density in the flow continuity and momentum equations. The model adopts the HLL approximate Riemann solver to handle the mixed-regime flows near the breach and the wetting-drying problem. The developed model has been tested against a lab experiment of dike-break flow over movable bed and a field experiment of sea dike breaching. The simulation results demonstrate that the model is capable of calculating the initial development stage of coastal barrier breaching under supercritical flow. Future work will improve the model to include waves for more general application in the coastal context., Published in Proceedings of the Coastal Sediments 11 Specialty Conference, p546-559, 2011. Presented at the Coastal Sediments 11 Specialty Conference held in Miami, FL on 2-6 May 2011. Prepared in cooperation with the National Center for Computational Hydroscience and Engineering, the University of Mississippi, University, MS.

A numerical model called GenCade is introduced that simulates shoreline change relative to regional morphologic constraints upon which these processes take place. The evolution of multiple interacting coastal projects and morphologic features and pathways, such as those associated with inlets and adjacent beaches can also be simulated. GenCade calculates longshore sediment transport rates induced by waves and tidal currents, shoreline change, tidal inlet shoal and bar volume evolution, natural bypassing, and the fate of coastal restoration and stabilization projects. It is intended for project- and regional-scale applications, engineering decision support, and long-term morphology response to physical and anthropogenic forcing. Capabilities of the model are illustrated by an application to the south shore of Long Island, NY. The Long Island application has multiple coastal structures and features that are maintained to varying degrees of frequency. Cumulative response of the beaches from a variety of coastal projects leads to complexity in regional coastal management. GenCade is presented as a tool to unify management of local projects at regional scales., Published in Proceedings of the Coastal Sediments 11 Specialty Conference, p1920-1932, 2011. Presented at the Coastal Sediments 11 Specialty Conference held in Miami, FL on 2-6 May 2011. Prepared in cooperation with the Department of Water Resources Engineering, Lund University, Lund, Sweden, and Golder Associates Inc., Redmond, WA. Sponsored in part by the U.S. Army Corps of Engineers, New York District.

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., Published in the Journal of Coastal Research, Special Issue n59 p98-110, 2011.

Our long terms goals are to understand sediment transport processes, the relevant physical forcing processes and the resulting morphologic evolution of river mouths and tidal inlets and shoals. Specific goals include understanding bedform characteristics (ripple to sandwave and sandbar scale) in relation to wave- and current-forced mean and turbulent flow. Objectives: 1. Quantify morphological change associated with storms and tidal forcing, and quantify the physical mechanisms causing the change (i.e., the specific wave-current-bathymetry interactions leading to divergence of sediment transport). 2. Measure the currents, sediment-transport processes and bedform evolution in the bottom boundary layer in the energetic ebb-tidal shoals, where nonlinear interactions between waves and tidal currents are critically important to the sediment transport and the morphological response to changing forcing conditions. 3. Develop instrumentation to make essential measurements for objectives 1 and 2. This includes a surface running REMUS-100 with a carrier phase GPS antenna that will remain exposed, and a multi-beam system for bathymetric surveys. Our Dopplers profilers are also in the process of being upgraded to bistatic convergent beam sampling for better resolution of near bed turbulence, Sponsored in part by Contract no. N00014-10-1-0768.

Ocean entrances to coastal lagoons are a complex, sensitive and important component of the coastal environment. They provide estuarine water exchange between inland waterways and the open ocean, and are increasingly the focus of urban development. Coastal lagoons that are only intermittently connected to the ocean are particularly sensitive since during periods of closure water quality issues are exacerbated, along with the increased risk of flooding.Mechanical clearance was undertaken in 2006 at the ocean entrance to Narrabeen Lagoon, Sydney, Australia, which intermittently opens and closes with the ingress of marine sand into the entrance restricting water exchange between the estuary and the ocean. This `instantaneous reset' of the system provided a unique opportunity to monitor and quantify generic inlet sedimentation processes and mechanisms. An intensive data collection campaign was undertaken for two years following the clearance including video image data, hydrodynamic measurements and detailed morphological surveys of the lagoon entrance system.This data set was used to quantify the sediment ingress flux and pathways within the accreting flood-tide delta of the lagoon entrance. It was found that ingress of sand into the system proceeds via a rapid landward infilling process with the location of the divergence point of the flood tidal current, available accommodation space within the entrance system and the influence of storm events being the key factors in the evolving morphodynamics of this type of coastal lagoon system.Classic inlet stability criteria were applied at the study site and it was found that the uncertainties in the determination of key parameters coupled with issues arising from compatibility of spatial and temporal scales preclude their use at this type of system. An alternative criterion is proposed which is an index of the tendency of an inlet toward instability and closure that is based on the evolution of the principle tidal constituent.

Four inlets (Johns Pass and Blind Pass; and New Pass and Big Sarasota Pass) in two multi-inlet systems along the West-central Florida coast were studied. Johns Pass, New Pass, and Blind Pass are dredged every 4-9 years, whereas Big Sarasota Pass has never been dredged. The goal of this study was to investigate the morphodynamics of the four inlets and the influences of channel dredging on the flow patterns over the ebb tidal delta and sediment bypassing. Time-series aerial photographs and bathymetric maps starting from the 1920s were analyzed to assess the pathways of sand bypassing and morphodynamics at the inlets. The Coastal Modeling System (CMS), computing wave, current, sediment transport, and morphology change of tidal inlets, was applied and reproduced the observed medium-term morphology changes. CMS is then used to investigate influences of channel dredging on inlet morphodynamics., Published in the Proceedings of the Coastal Dynamics International Conference 2009 (6th), held in Tokyo, Japan, on 07-11 September 2009. The original document contains color images.

Tidal inlets are part of the coastal sediment-sharing system, and an inlet will modify the nearshore and estuary morphology as well as the up-drift and down-drift beaches. Morphologic response to an inlet varies over several time and spatial scales. This document discusses inlet morphology and related functional design considerations that must balance navigation and shore-protection requirements. The first half of the document reviews selected material on the morphology of inlets and introduces empirical predictive expressions found useful for engineering. The second half of the document concerns aspects of engineering of tidal inlets.

This Coastal and Hydraulics Engineering Technical Note (CHETN) presents numerical simulations investigating how the loss of wetlands in estuaries modifies tidal processes in inlet navigation channels. The implications for wetland loss and construction of wetlands to tidal inlets and navigation channels are discussed, and hypotheses are presented for possible engineering approaches to mitigate wetland loss and improve the sedimentary sustainability of constructed wetlands.

Recent estimates by Intergovermental Panel on Climate Change (2007) are that global sea level will rise from 0.18 to 0.59 m by the end of this century. Rising sea level not only inundates low-lying coastal regions, but it also contributes to the redistribution of sediment along sandy coasts. Over the long-term, sea-level rise (SLR) causes barrier islands to migrate landward while conserving mass through offshore and onshore sediment transport. Under these conditions, coastal systems adjust to SLR dynamically while maintaining a characteristic geometry that is unique to a particular coast. Coastal marshes are susceptible to accelerated SLR because their vertical accretion rates are limited and they may drown. As marshes convert to open water, tidal exchange through inlets increases, which leads to sand sequestration on tidal deltas and erosion of adjacent barrier shorelines.

Chilaw inlet, with the affiliated lagoon, is located on the west coast of Sri Lanka about 120 km north of the capital Colombo. Each year during the summer monsoon, which lasts from May to September, the inlet closes due to a sand spit forming across the inlet. The closure results in impeded access to the sea for the fishermen, who use the lagoon as anchorage for their boats, and in deteriorated water quality in the lagoon. The theory behind inlet closure was studied in the present investigation in order to understand the governing physical mechanisms related to closure at Chilaw inlet. A measurement campaign, lasting from May to July (2006), was also performed resulting in topographic maps describing the morphological changes at the inlet during the summer monsoon. Increased longshore sediment transport during the summer monsoon 2006 and cross-shore sediment transport from an ebb shoal, located seaward of the inlet, initiated spit formation, which by early July led to an inlet closure. By the end of July a breaching of the spit occurred due to a combination of decreased longshore sediment transport and large amounts of wave energy working on the spit. Based on wave data and topographic maps two mathematical models were developed, one basic and one more advanced. The sediment pathways at the inlet were identified and quantified, and through a reservoir-type model the spit growth was simulated at the inlet. Both models described the observed spit growth fairly well but, since the advanced model involves more assumptions and coefficients than the basic model, the latter on is judged to be the most reliable and suitable with regard to the data available. In order to obtain a better result with the advanced model more physical processes have to be measured and quantified.

Repeated side-scan sonar and multi-frequency bathymetric surveys, accompanied by accurate, high resolution, and repeatable navigation, were conducted in the vicinity of a tidal inlet to define the length and time scales associated with bedforms and channel shoaling in a structured tidal inlet. The study site, St. Marys entrance channel along the Georgia/Florida border (Fig. 1), has a dredged channel approximately 46-52 feet in depth at a datum of mean low water (MLW), bordered by a large ebb tidal delta. The tidal inlet serves Cumberland Sound, Kings Bay, and associated waterways, providing a large discharge of water from the inlet that creates bedforms and channel shoaling, given the abundance of sand-size sediment in the vicinity. The jettied inlet produces flows that are predominantly tidally-driven, whereas farther offshore the driving forces consist predominantly of waves and storm-generated flows. In the channel reaches (Table 1) between these two areas, combined wave/steady flows are present, creating a myriad of scales of bedforms and shoaling patterns, emphasizing the difference in these scales between the three different flow regimes. The results provide an important data base for quantifying shoaling processes and mechanisms in tidal inlet channels., Funding was provided by the National Oceanic & Atmospheric Administration's Sea Grant Program through Grant NA860-A-D-090.

Repeated side-scan sonar and multi-frequency bathymetric surveys, accompanied by accurate, high resolution, and repeatable navigation, were conducted in the vicinity of a tidal inlet to define the length and time scales associated with bedforms and channel shoaling in a structured tidal inlet. The study site, St. Mary's entrance channel along the Georgia/Florida border (Fig. I), has a dredged channel approximately 46-52 feet in depth, bordered by a large ebb tidal delta. The tidal inlet serves Cumberland Sound, Kings Bay, and associated waterways, providing a large discharge of water from the inlet that creates bedforms and channel shoaling, given the abundance of sand-sized sediment in the vicinity. The jettied inlet produces flows tht are predominately tidally-driven, whereas farther offshore the driving forces consist predominately of waves and storm-generated flows. In the channel reaches (Table 1) between these two areas, combined wave-steady flows are present, creating a myriad of scales of bedforms and shoaling patterns. This study was designed to elucidate the time and space scales of these variable bedforms and shoaling patterns, emphasizing the difference in these scales between the three different flow regimes. The results provide an important data base for quantifying shoaling processes and mechanisms in tidal inlet channels., Funding was provided by the National Oceanic Atmospheric Administration under Sea Grant No. NA860A-D-SG090.

Barrier island coasts are a common feature in many parts of the world. An example is the Wadden coast of The Netherlands, Germany and Denmark. These coasts consist of barrier islands separated by tidal inlets with at the landward side tidal basins.Characteristic for the Wadden Sea is that the tidal basins are not completely separated,but are connected via topographic highs allowing exchange of water between the basins. As a result the tidal inlets that connect the basins to the North Sea will interact. The focus in this thesis is on the effect of this interaction on the cross-sectional equilibrium and stability of tidal inlets that are part of a double inlet system. The knowledge gained in this study will help to develop rational management plans for this kind of system. In determining the equilibrium values and stability of cross-sectional areas of the inlets use is made of flow diagrams. A flow diagram consists of the equilibrium flow curves of each inlet and a flow field showing the adaptation of the inlet cross-sections after the system has been removed from equilibrium. Each intersection of the equilibrium flow curves represents a stable or unstable equilibrium. The equilibrium flow curve for each inlet is the locus of the values of the cross-sectional areas for which the velocity amplitude in the inlet equals the equilibrium velocity i.e. approximately 1 m/s according to ESCOFFIER [1940]. As a start the double inlet system is schematized as a basin connected to the ocean by two channels. The water surface area of the basin is assumed constant and water levels are assumed to fluctuate uniformly. On the seaward side a simple harmonic, semidiurnal tide is used to force the system. Analyzing the double inlet system under these conditions by means of the flow diagrams leads to the conclusion that a stable equilibrium of the two inlets does not exist. Ultimately only one inlet remains open and the other will close. This confirms the earlier conclusions of VAN DE KRE, Civil Engineering and Geosciences

The apparent persistence and stability of multiple tidal inlets in coastal lagoons are important for a variety of reasons, such as water quality, navigability and beach/barrier stability. To identify and study the processes controlling the persistence of multiple tidal inlets, the hydrodynamics of the system have to be better understood. This project is part of a larger study (INDIA) examining general tidal inlet processes. The present components consist of a numerical simulation study of processes controlling multiple inlet stability, combined with exhaustive field measurements. This report addresses only the second component. The analysis uses as study site and main source of data the Ria Formosa lagoon in Portugal, which has multiple and historically persistent inlets. For the numerical simulation model, field measurements are needed to provide (i) updated bathymetry of the inlets, in situ measurements of (ii) water level fluctuations within the estuary and (iii) flow velocities through the inlets. This report gives first a brief description of the instrumentation used in the field (section 2), then describes the methods used to deploy the instruments, perform the surveys and gather the data (section 3), explains the procedures for data reduction and show some results (section 4 and Annex)., Funding was provided by WHOI Sea Grant, EU MAST III Program, UNAM, Mellon Foundation and Rinehart Coastal Research Center.

In March 2002, under the direction of the first author, a rapidly migrating inlet located in New Hanover County, North Carolina was relocated. The original entrance to Mason Inlet was closed, and the inlet was reopened approximately 850 m (2,800 ft) to the north. In addition, a 1,400-m (4,580 ft) long channel was dredged between the new inlet and the Atlantic Intracoastal Waterway (AIWW), and a sedimentation basin was constructed west of the new inlet entrance. Monitoring was initiated to determine if the downdrift beaches receive sediment from breakup of the abandoned ebb shoal and to assess development of the new ebb shoal, including natural sand bypassing. This paper examines ebb shoal development, inlet cross-section equilibration, beach response, and changes in the tidal prism and flow distribution through the primary two tidal channels connecting the new inlet with the AIWW following the inlet's relocation. Locational and cross-sectional stability of the entrance channel are also discussed., Presented at the International Symposium on Coastal Engineering and Science of Coastal Sediment Processes held in Clearwater Beach, FL on 18-23 May 2003 (Coastal Sediments '03). The original document contains color images.

The equilibrium-area concept for tidal inlets has been a useful approach to understand the adjustment of an entrance channel's minimum cross-sectional area to the basic hydraulic and sedimentation characteristics of the inlet and bay it serves. This paper examines the concept in terms of inlets that apparently are not in equilibrium, maintaining a smaller area than the equilibrium area that is indicated by the Escoffier diagram. Is the Escoffier approach too simplified or is the response sometimes a very long-term process? Other methods and concepts imply equilibrium area values smaller than predicted by the Escoffier approach., Presented at the International Symposium on Coastal Engineering and Science of Coastal Sediment Processes held in Clearwater Beach, FL on 18-23 May 2003 (Coastal Sediments '03). The original document contains color images.

This Coastal and Hydraulics Engineering Technical Note (CHETN) provides information on erosion which occurs on the banks (or shoulders) of tidal inlets stabilized with jetties. The causes for initiation of this erosion area are discussed, and potential solutions for reducing/preventing the erosion are presented., The original document contains color images.

This study focuses on modeling the 2D, depth-averaged circulation of Bay St. Louis in the northeastern Gulf of Mexico that is driven by waves and tides using a coupled hydrodynamic-wave model. The wave-tide coupled circulation within the inlet is examined during the flood, slack, and ebb phases of the tidal cycle. The wave height field, current velocity and sea surface elevation are analyzed to determine the effects of wave-current interaction. The influence of the various forcings on bay/inlet circulation is further investigated by the introduction of Lagrangian tracers. Lagrangian tracers are a reasonable indicator of how circulation patterns affect the motion of sediment particles or passive biological organisms such as fish larvae. Wave-current interaction is simulated by iteratively coupling the depth-integrated ADCIRC-2DDI hydrodynamic model to the phase-averaged spectral wave model SWAN. ADCIRC-2DDI is a fully developed, 2-dimensional, finite element, barotropic hydrodynamic model capable of including wind, wave, and tidal forcing as well as river flux into the domain. The wave-hydrodynamic model coupling i captured through the following approach. First, radiation stress gradients, determined from the SWAN wave field, serve as surface stress forcin in ADCIRC. Elevation and currents com uted from ADCIRC are subse uentl in ut into the SWAN model.

This report documents an investigation of the coastal and inlet physical processes acting at the San Bernard River mouth, Texas. The U.S. Army Engineer District, Galveston, requested the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), to conduct this study to assist in formulation and assessment of alternatives for improving navigation along the Gulf Intracoastal Waterway (GIWW) between the Brazos River and the San Bernard River and vicinity. In recent years, a spit has grown from northeast to southwest across the San Bernard River mouth. The migrating river mouth is narrowing, and sediment shoaling landward of it has reduced the river's discharge to the Gulf of Mexico. River flow is diverted into the GIWW, increasing the current velocity in an unpredictable way and possibly increasing sediment shoaling at the intersection of the river and the GIWW, as well as to the east at the west floodgate to the Brazos River. The present study was performed to identify and evaluate alternatives for maintaining the San Bernard River mouth. The San Bernard River is located in north-central Texas and flows through the alluvial valleys of the Colorado River and Brazos River. The central Texas coasts spans several zones from humid in the north to dry subhumid in the south. Average annual rainfall ranges from 104 to 125 cm, with large variations possible between droughts and precipitation brought by tropical storms. The San Bernard River has a much smaller drainage area than either the Colorado River or the Brazos River, with correspondingly much weaker flows and sediment discharge. Therefore, local storms primarily determine its flow. This study was organized in three components as an analysis of the coastal geomorphology and sediment-transport processes, a hydraulic analysis of the river and tidal flow, and a synthesis of results leading to development and evaluation of alternatives., Original contains color plates: All DTIC reproductions will be in black and white.

This Coastal and Hydraulics Engineering Technical Note (CHETN) discusses selected morphologic symmetries of ebb shoals and channels at tidal inlets with implications for maintenance of navigation channels and sediment bypassing to the adjacent beaches., The original document contains color images.

This study was designed to examine the relationship among channel area, tidal period, tidal prism, and maximum channel velocity. Movable-bed model experiments were run to define an equilibrium area for different tidal periods and sediments. The magnitude of the areas measured provided additional data for the relationship of the tidal prism versus minimum channel area in a size range slightly larger than previous laboratory data in the continuum to very large field inlets. These data may help define the tidal prism-minimum channel cross-sectional area relationship in the midrange channel size.

Tidal motion and inlet processes were investigated in Ponce de Leon (Ponce) Inlet, Florida, and its bay channels through a 10-week data-collection campaign and two-dimensional numerical simulation modeling. Water level and current were measured at six locations spanning the ebb shoal, inlet, and bay channels. Measurements revealed that the inlet was flood dominated during the data-collection period. The flood dominance may have been enhanced by a net influx of water during the measurement period, which was captured at two measurement stations in the bay channels located 5 km away from the inlet. Scour, erosion, and sedimentation are problems faced at Ponce Inlet, and calculations suggest tide-related circulation patterns contribute to problematic hot spots. Tidal attenuation was calculated along a 7 km transect from the ebb shoal, through the inlet, and south along the Indian River North., Published in the Journal of Coastal Research, v16 n3 p840-852, Summer 2000. Prepared in cooperation with the Division of Marine and Environmental Systems, Florida Inst of Technology, Melbourne. Sponsored in part by USACE Jacksonville District and the Ponce de Leon Inlet Navigation District.

The apparent persistence and stability of multiple tidal inlets in coastal lagoons are important for a variety of reasons, such as water quality, navigability and beach/barrier stability. To identify and study the processes controlling the persistence of multiple tidal inlets, the hydrodynamics of the system have to be better understood. This project is part of a larger study (INDIA) examining general tidal inlet processes. The present components consist of a numerical simulation study of processes controlling multiple inlet stability, combined with exhaustive field measurements. This report addresses only the second component. The analysis uses as study site and main source of data the Ria Formosa lagoon in Portugal, which has multiple and historically persistent inlets. For the numerical simulation model, field measurements are needed to provide (i) updated bathymetry of the inlets, in situ measurements of (ii) water level fluctuations within the estuary and (iii) flow velocities through the inlets. This report gives first a brief description of the instrumentation used in the field (section 2), then describes the methods used to deploy the instruments, perform the surveys and gather the data (section 3), explains the procedures for data reduction and show some results (section 4 and Annex).

After consulting the "Department of Environment" in Australia it was suggested that an extensive generic study about Tidal Inlets on Littoral drift shores gives them an insight in the processes at work and also the possibilities to improve the stability in order to make tidal inlets suitable for safe navigation. This report describes the most important issues related to tidal inlets on littoral drift shores in general. It is written with the intention to provide some general information to readers who are interested in tidal inlets in general. However this report also provides some specific information to be able to study the stabilisation of the Nerang River Entrance, Queensland Australia., Hydraulic Engineering, Civil Engineering and Geosciences

In this report a model has been derived to simulate morphological behaviour under tidal conditions. The model is based on the set of equations of motion and mass-balance for both water and sediment. The study focused on the underlying assumption that the kinematic response of the water movement on the bottom variation is much stronger than the dynamic response. Application of the transport-field method (chapter 4) as suggested by De Vriend (1985) has been examined. The performed study is a next step towards a more efficient way of morphodynamic modelling and may contribute to a more thorough understanding of morphological models and processes in tidal regions., Hydraulic Engineering, Civil Engineering and Geosciences

The coastlines of the world's oceans encompass a tremendous variety of geomorphic and geologic structures. They range from rocky cliffs to sandy barrier beaches to low-lying swampy wetlands. The geomorphic forms were created by the interaction of antecedent geology, physical dynamic processes, and man- made intervention. Variable features are usually composed of unconsolidated materials that respond rapidly to changes in the dynamic environment. More stable features are usually associated with consolidated rock or occur in quiescent environments. The geologic history of shorelines can be inferred from a careful study of geomorphic structures, coupled with additional data on physical processes and historic events. Many of the study techniques are relatively simple, consisting of analysis of existing maps and historical sources. An understanding of the processes which have shaped the shore is crucial to the design of coastal structures and to the intelligent management of coastal resources and habitats. In addition, understanding of the form/process relationships between geomorphology and dynamics may allow coastal scientists to more accurately predict the results of construction or other modifications along the shore.

Repeated side-scan sonar and multi-frequency bathymetric surveys, accompanied by accurate, high resolution, and repeatable navigation, were conducted in the vicinity of a tidal inlet to define the length and time scales associated with bedforms and channel shoaling in a structured tidal inlet. The study site, St. Marys entrance channel along the Georgia/Florida border (Fig. 1), has a dredged channel approximately 46-52 feet in depth at a datum of mean low water (MLW), bordered by a large ebb tidal delta. The tidal inlet serves Cumberland Sound, Kings Bay, and associated waterways, providing a large discharge of water from the inlet that creates bedforms and channel shoaling, given the abundance of sand-size sediment in the vicinity. The jettied inlet produces flows that are predominantly tidally-driven, whereas farther offshore the driving forces consist predominantly of waves and storm-generated flows. In the channel reaches (Table 1) between these two areas, combined wave/steady flows are present, creating a myriad of scales of bedforms and shoaling patterns, emphasizing the difference in these scales between the three different flow regimes. The results provide an important data base for quantifying shoaling processes and mechanisms in tidal inlet channels.