Dapeng Bay is located in the southwest coast of Taiwan. It is a cystic shaped shallow lagoon, which has only one entry for exchanging lagoon water with the coastal current. The water quality is depending on the refreshing rate and the mixing level in the lagoon. In order to understand the circulation pattern monthly measurements using an ADP are carried out. Three water quality monitoring stations are constructed for regular online observation of the water quality in the lagoon. The flows are on the west-northwest direction during the flood and toward the west during ebb. Strong currents are observed in the tidal inlet channel. The general circulation patterns are mainly dominated by tide though wind effects can observed from the measurements. This study established a three-dimensional hydrodynamic modeling system using the FVCOM model developed at the U.S. Marine Ecosystem Dynamics Modeling Laboratory for the simulation of Dapeng Bay currents. The study includes the comparison of the recent circulation and the flow fields after broaden of the inlet navigation channel. This will change not only the shape but also dredge the channel deeper. These variations may differ the circulation patterns and the exchange quantities as well. The model results are first compared with the observations for the present situation as calibration. The simulation results for the studies of the changing of the inlet channel will be discussed.

Contemporary sediment transport, suspended sediment flux, rates of intertidal sedimentation, and Holocene sedimentation history are assessed for Hamford Water, a small meso-tidal inlet and saltmarsh embayment in Essex, UK. Sediment transport rates are calculated using semi-empirical equations; suspended sediment flux is computed by integration of suspended sediment concentration and velocity across the inlet throat; intertidal sedimentation rates are assessed from monitoring of discrete markers on saltmarsh and mudflat; and Holocene sedimentation is estimated from radiocarbon dating of buried organic layers, sampled using a vibrocorer. Results show a tidal regime typical of ebb-dominated inlets: moderate, ebb-dominant flow (==1 m S·l) in the central ebb channel is matched by similar flood-dominant marginal channel flows. The sediment dynamics are not influenced by any fluvial input; there is negligible fresh water input. The net direction of sediment transport is predominantly ebb-orientated. Coarse sand transport pathways are circulatory and dependent on longshore drift. Sand (D = 0.25 mm) enters at the margins and is expelled in the central ebb channel. Negligible sand is transported further landward than the mouth; intertidal sedimentation relies mainly on levels of suspended sediment. Rates of intertidal sedimentation are spatially variable: tidal creek sedimentation is greater than saltmarsh, with a mean rate of 4.2mm yr"l. Buried organic horizons. radiocarbon dated to 600 years BP, are attributed to reclaimed land levels. Holocene sedimentation rates since 4300 years BP, estimated from 14C dating of shell bands. accord with current estimates of sea-level rise of approximately 1 mm i 1 • The role and evolution of the inlet entrance and ebb tidal delta are seen as critical to the evolution of the embayment as a whole. The interaction of the embayment with the adjacent coastal zone considered essential when fonnulating shoreline management plans. Hamford Water is considered an integral part of the Stour/OrwelllNaze coastal system.

Shippagan Gully is a highly dynamic tidal inlet located on the Gulf of St-Lawrence near Le Goulet, New Brunswick. This tidal inlet is highly unusual due to the fact that the inlet has two open boundaries with phase lagged tidal cycles that drives flow through the inlet. Over the past few decades, the shipping activities through the inlet have been threatened due to the narrowing of the navigation channel caused by deposited sediment on the east side of the channel. Many engineering projects have been undertaken at Shippagan Gully in order to try and mitigate the deposition problem. However, these attempts have either been unsuccessful or the engineered structures have deteriorated over the years. This study uses the CMS-Flow and CMS-Wave numerical models to provide guidance concerning the response of the inlet to various potential interventions aimed at improving navigation safety.

Shippagan Gully is a highly dynamic tidal inlet located on the Gulf of St-Lawrence near Le Goulet, New Brunswick. This tidal inlet is highly unusual due to the fact that the inlet has two open boundaries with phase lagged tidal cycles that drives flow through the inlet. Over the past few decades, the shipping activities through the inlet have been threatened due to the narrowing of the navigation channel caused by deposited sediment on the east side of the channel. Many engineering projects have been undertaken at Shippagan Gully in order to try and mitigate the deposition problem. However, these attempts have either been unsuccessful or the engineered structures have deteriorated over the years. This study uses the CMS-Flow and CMS-Wave numerical models to provide guidance concerning the response of the inlet to various potential interventions aimed at improving navigation safety.

Tidal inlets play a significant role in barrier island sustainability along the barrier islands of southern Louisiana. With increasing tidal prism, major changes are taking place within and adjacent to the inlets. The purpose of this thesis is to examine how Caminada Pass, a tidal inlet along the Caminada-Moreau headland, has evolved through time. Fundamental to this effort is evaluating which processes have contributed toward inlet evolution and what is the response of the inlet-bordering barrier island shorelines of Grand Isle and Elmer’s Island. This effort summarizes previous results and utilizes published bathymetric data, aerial photographs, vector shorelines, satellite images, and seafloor grab samples. The intent of this research is to document the variety of data that are available for future studies of Caminada Pass, an evaluation of long and short-term changes to the system, and an overall better understanding of the inlet dynamics of Caminada Pass.

Numerical modeling systems are very important tools to study tidal inlets. In order to test its capability and accuracy of solving multi-inlet system problems, this study selected two widely used numerical modeling systems: Coastal Modeling System (CMS) and Delft3D Modeling Package. The hydrodynamics modules of the two modeling systems were tested at John's Pass and Blind Pass, Florida, a dual-inlets system, based on a similar modeling scheme. Detailed bathymetric surveys and hydraulic measurements were conducted to collect water depths, tide conditions, wave and current velocities as the input data as well as verification data for the models. A comparison study was conducted by comparing computed hydrodynamic results from both models with the extensive field measurement data. Results show that both of the modeling systems yield better prediction for water levels than for current velocity. Furthermore, under the similar modeling scheme, Delft3D was able to capture the measured tidal phase lag between the ocean boundary and the coastal inlet, therefore gave better water level prediction than the CMS model. However, the CMS yielded current velocities that are closer to the measured values than the DELFT3D model. CMS has a more user-friendly Graphic User's Interface (GUI) for input data preprocessing and plotting and visualization of output data. Delft3D has faster calculation speed.

Shippagan Gully is a tidal inlet located near Shippagan, New Brunswick on the Gulf of Saint Lawrence. It is a particularly complex tidal inlet due to the fact that its tidal lagoon transects the Acadian peninsula and is open to the Bay des Chaleurs at its opposite end. As such, two open boundaries with phase lagged tidal cycles drive flow through the inlet, alternating direction with each tide and reaching velocities in excess of 2m/s. Hydrodynamic and morphological processes at the site are further complicated by the presence of a highly variable wave climate. Presently, shipping practices through the inlet are limited due to continual sedimentation within and immediately offshore from Shippagan Gully. As such, an extensive field study, desktop analysis and numerical and morphological modeling of Shippagan Gully have been conducted in order to provide guidance for future works. Modeling was conducted using the CMS-Wave and CMS-Flow numerical modeling system.

Shippagan Gully is a tidal inlet located near Shippagan, New Brunswick on the Gulf of Saint Lawrence. It is a particularly complex tidal inlet due to the fact that its tidal lagoon transects the Acadian peninsula and is open to the Bay des Chaleurs at its opposite end. As such, two open boundaries with phase lagged tidal cycles drive flow through the inlet, alternating direction with each tide and reaching velocities in excess of 2m/s. Hydrodynamic and morphological processes at the site are further complicated by the presence of a highly variable wave climate. Presently, shipping practices through the inlet are limited due to continual sedimentation within and immediately offshore from Shippagan Gully. As such, an extensive field study, desktop analysis and numerical and morphological modeling of Shippagan Gully have been conducted in order to provide guidance for future works. Modeling was conducted using the CMS-Wave and CMS-Flow numerical modeling system.

Shippagan Gully is a tidal inlet located near Shippagan, New Brunswick on the Gulf of Saint Lawrence. It is a particularly complex tidal inlet due to the fact that its tidal lagoon transects the Acadian peninsula and is open to the Bay des Chaleurs at its opposite end. As such, two open boundaries with phase lagged tidal cycles drive flow through the inlet, alternating direction with each tide and reaching velocities in excess of 2m/s. Hydrodynamic and morphological processes at the site are further complicated by the presence of a highly variable wave climate. Presently, shipping practices through the inlet are limited due to continual sedimentation within and immediately offshore from Shippagan Gully. As such, an extensive field study, desktop analysis and numerical and morphological modeling of Shippagan Gully have been conducted in order to provide guidance for future works. Modeling was conducted using the CMS-Wave and CMS-Flow numerical modeling system.

A program for selecting the optimal wave conditions for morphodynamically accelerated simulations of coastal evolution (‘OPTIWAVE’) has been constructed using a novel Genetic Algorithm approach. The optimization routine iteratively reduces the complexity of an incident wave climate by removing the events that contribute least to a target sediment transport pattern, and then ‘evolving’ a new set of weights for the remaining wave conditions such that the target sediment transport pattern (and magnitude) is optimally maintained. The efficacy of OPTIWAVE to satisfactorily reduce the incident wave climate is tested against three coastal modeling paradigms of increasing complexity: (a) A simple 1-D beach profile model (no tides); (b) A 2-D micro-tidal beach; (c) A tidal inlet, where the interaction between waves, tides, and wave-current interaction, adds significant complexity. The simple test case for a beach profile shows that OPTIWAVE is successfully capable of maintaining a target profile-integrated long-shore sediment transport rate. The calculated skill and RMSE of the reduced wave climate is a good indicator of its ability to reproduce the target sediment transport pattern. The optimal number of wave conditions is identified by an ‘inflection point’ at a critical number of wave conditions, where less complex a wave climate results in substantially reduced skill (increased error). The assumption that the ability of OPTIWAVE to reproduce a target sediment transport field is a valid proxy for the potential skill of a morphologically accelerated simulation is assessed for the case of a 2D micro-tidal beach. The skill of the accelerated models, which use a state-of-the-art ‘event-parallel’ method of simulating bed evolution from multiple wave conditions in parallel, is tested against a ‘brute force’ reference simulation that considers the full wave forcing. A strong positive correlation is found between the skill of the reduced wave climate to reproduce a target sediment transport pattern, and the resultant skill of the accelerated morphodynamic model against the ‘brute force’ reference simulation. Finally, the ability to combine reduced wave and tide climates for simulations that must consider both wave and tidal forcing, is assessed against a ‘brute force’ reference simulation of the seasonal evolution Ancao inlet, Algarve, Portugal. The reference simulation is validated against a comprehensive field dataset collected in 1999, and is shown to qualitatively reproduce key features of inlet behavior over a seasonal period. The combination of reduced wave and tidal climates in accelerated ‘event-parallel’ models did not successfully reproduce the reference seasonal morphological evolution of Ancao inlet. Assessing the model Brier Skill Score showed that the model was more successful in reproducing the reference morphology in areas dominated by tidal forcing, but did not have any predictive power in regions where morphological evolution is due to some combination of both wave and tidal processes.