The tide transports the mud to the port and channel. For both layouts, the most substantial part of the channel is located in the areas with mild sediment transport mechanisms. The channels in the inner basin tend to refill in more than ten years, which is a low rate. These changed hydrodynamics initiate erosion and sedimentation patterns that change the tidal basin bathymetry. The channel's route of Alternative 1A is in the natural trajectory of the tidal wave. The hydrodynamics of the area are less impacted for Alternative 1A than for Alternative 1B because no new opening through which water flows created. The navigation channel of Alternative 1B crosses the barrier island and thus creates a new opening to the lagoon. The navigation channel of Alternative 1A enters the lagoon through the northern inlet. In the study, two alternative port layouts area compared with each other. The large sediment flume going southward in the basin is accumulated in the channel. The low export of mud is because the navigation channels in the lagoon become mud traps. Although the northern area turns to ebb dominance, mud does not leave the basin in higher numbers. From a flood dominant area, the northern area changes to ebb dominance. The river discharges have the most substantial influence in the north now because it encounters less resistance from the tidal wave. The channel trajectories are to the west and south. The tidal wave follows the path with the least resistance, which the newly dredged channel. When the alternatives are constructed in the area, the hydrodynamic climate changes. Due to a moderate wave climate, a small longshore southward transport is initiated.
Most of the mud originating from the river is transported directly to the northern inlet through the river channel. In the wet period, the river discharge forces the northern area in ebb dominance, not letting mud enter the tidal basin anymore.
A mud flume goes southward over the tidal basin. During the dry season, the lagoon is flood dominant importing mud from the adjacent coast. It is, however, the tide that initiates the most extensive sediment transport. The results show that the Rio Escondido discharges a large amount of sediment into the tidal basin during the wet period. As the waves are mainly from the east-north-east with a height of 1 m, a moderate southward longshore transport is initiated the year-round. Next to the hydrodynamics inside the lagoon, the adjacent coast is under the influence of a swell wave climate. As the dominant hydrodynamics change over the year, the sediment fluxes change with them. Besides the river discharge, the tidal wave influences sediment transport when it enters the tidal basin.
The river delivers a large amount of mud, particularly in the wet period. A distinct wet and dry season is observed, changing the hydrodynamic influences over a year. The river channel and tidal channels at the inlets have a depth of 4 m-MSL. These shallow parts consist mainly of mud. The lagoon has large parts of shallow depths of around the 1.5 m-MSL. The area is analysed with the help of a conceptual model that is supported by the process-based model Delft3D. Besides this, sedimentation rates in the navigation channel and erosion rates at the coast are calculated. A qualitative analysis of the hydrodynamics and sediment fluxes in the area is made. In addition, the influence of the port structures on the lagoon is analysed. In this study, the hydrodynamics and morphodynamics of the area are assessed. A port is constructed in the area of Bluefields Bay, which characterises as a lagoon-shaped estuary.
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