Ports are located in deltas and dynamic coastal regions with large loads of fine sediment. Ports also enhance the import of marine sediment by channel and basin deepening. This results in the need for extensive maintenance and sediment management. Finding an effective and efficient sediment man­agement strategy is difficult. This research dives into the current sediment management approaches and innovations to develop a decision-­making approach to find the most suitable and sustainable sed­iment management strategy for a port.

There are several ways to optimize the sediment management in a port. With the principle to con­ sider sediment as a value resource to the port and the coastal system, rather than a waste, the sediment management hierarchy is obtained. This hierarchy consists of Prevent and Reduce, Recycle and Reuse and Disposal to find a sustainable sediment management strategy. Various Prevent and Reduce and Recycle and Reuse examples and methods are analysed in this research to identify their potential for sustainable sediment management. Furthermore, based on literature study, expert interviews and a workshop at Arcadis input is generated to propose a decision­-making approach. This research devel­ops an approach and a tool considering all the aspects of sediment management and for assessing potential strategies for sediment management in a port.

The decision­-making approach considers four steps to find a sediment management strategy. The first step, sediment management objectives, defines the objectives of the stakeholders for the strategy. In the second step, fit to case, all the sediment management methods are considered and the potential strategies are defined. The third step, assessment of potential strategies, assesses the performance of each strategy with performance indicators in the decision­-making tool. The performance indicators are selected based on the assessment categories and objectives. In the final step, meeting the objectives, the most suitable strategy is proposed and described for the long-­term sediment management in the port. This approach supports the process to optimize sediment management in a port.

The proposed decision-­making approach is applied and further developed with a case study on Porto Amboim. Porto Amboim is a port on the west coast of Angola. The port operates for the offshore industry and is currently experiencing sedimentation problems. The northward directed natural long­ shore sediment transport is interrupted by the port’s breakwater, resulting in sedimentation around the breakwater and at the lee side of the breakwater. This interruption disturbs the sediment balance in the region causing erosion problems at the down drift side of the port. The decision­making approach and tool are used to find a potential sediment management strategy for Porto Amboim. This potential strat­egy for Porto Amboim uses a sediment trap to manage the sediment in the region, ensuring sufficient port operations and restoring the sediment balance along the coast.

In order to use the approach in a generic way the results are reflected upon and a validation on the approach is performed. The reflection showed some uncertainties and limitations to the approach and tool because of the available information on the case. However, still two suitable strategies have been obtained for Porto Amboim. In the validation the approach has been applied on a second case study. This validation showed the potential for generic use of the decision-making approach and tool for sediment management. From the reflection and validation can be concluded that the available information determines the level of detail of the assessment of the potential strategies.

The main objective of this study was to explore the potential dredging and sediment management strategies to optimize sediment management in the port towards more sustainable methods, develop a decision-­making tool and apply the tool in a specific case study. From this research the following can be concluded, the decision­-making approach is considered a suitable approach to find a sediment management strategy for a port. All aspects of sediment management are considered and assessed. Therefore, further development of the tool and innovations in more aspects of sediment management are recommend. Yet, this research, the approach, and the innovative methods for sediment manage­ ment show a great potential for more sustainable maintenance strategies in the future.

To improve the socioeconomic situation in the Republic of Nicaragua, the government has decided to strengthen the country’s transport infrastructure by building a port on the Caribbean coast. The future port will be in Bluefields Bay, which can be characterised as a lagoon-shaped estuary. The inner basin is connected to the sea by two tidal inlets, located north and south of a barrier island. This study assesses the hydrodynamics and morphodynamics of the area; in addition, it analyses the influence of the port structures on these natural processes. A qualitative analysis of the hydrodynamics and sediment transport in the area is conducted, and sedimentation rates in the navigation channel and the erosion rates of the coast are calculated. The area is analysed with the help of a conceptual model that is supported by the process-based model Delft3D. Large parts of the area consist of shallow depths of around 1.5 m below mean sea level (MSL). The bed of these shallow parts consists mainly of mud. In those areas with a depth of more than 5 m below MSL, which are the river channel and the tidal channels at the inlets, the flow velocity increases, and a more substantial fraction of sand can be observed. In the data analysis, distinct wet and dry seasons can be observed; these seasons change the hydrodynamic influences over the course of the year. The river discharge increases by a factor of 10 during the wet season. In addition, the river delivers large quantities of mud, particularly during the wet period. When the tidal flow enters the lagoon, it influences sediment transport. As the dominant hydrodynamics change throughout the year, the sediment fluxes change with them. Beyond the hydrodynamics within the lagoon, the adjacent coast is under the influence of a swell wave climate. As the waves mainly come from the east-northeast at a height of 1 m, a moderate southward longshore transport is initiated year-round. The Delft3D model is used to analyse the hydrodynamics and sediment transport of the area in more detail. The model is used to analyse the flow magnitudes and directions. This approach allows the dominant hydrodynamic components to be identified. The most relevant hydrodynamic components are considered in the Delft3D model. These include tide, river discharge, waves, and wind. The 2D mode is sufficient to model these hydraulic components. Because of the hydrodynamic climate changes that occur throughout the year due to changes in the meteorological climate, the simulation period is one representative year. The model is calibrated and validated by means of phenomenological calibration and expert judgement, as field data is scarce.