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. ... Read more

Bardawil Lagoon is a tidal lagoon situated at the northern coast of the Sinai Peninsula in Egypt. It’s two artificial inlets, Boughaz 1 in the West and Boughaz 2 in the East, provide a connection to the Mediterranean Sea. They enable the water bodies to interact and support fish migration. Currently, regular maintenance dredging works are necessary to keep the two inlets open.
The objective of this thesis is to analyse the effect of interventions applied to the two inlets on the lagoon-sea interaction, with the goal of transforming the present, unstable inlet system towards a stable tidal inlet lagoon by adapting one or both of the present inlets. This study is conducted on three system phases, being Phase 0, Phase 1 and Phase 2. Phase 0 consists of the initial situation without any interventions; Phase 1 contains the effect of adaptations to the Boughaz 1 inlet, and Phase 2 includes adaptations to Boughaz 2 in addition to the changes made in Phase 1. The new design in Phase 1 and Phase 2 consists of a deeper inlet cross-sectional area, the dredging of an approach channel, the addition of a nourishment, and the removal of the present breakwaters. Design elements are processed using a 2D-H Delft3D Flexible Mesh model and analysed under tide-only conditions with and without a prevailing wind climate added. Evaporation effects are included after the model calculations are made. The results are mainly assessed are the interaction with the Mediterranean Sea, the sediment transport character, and the inlet stability according to the Escoffier curve. Moreover, an analysis is made on the flushing of the lagoon and the effect of a prevailing wind pattern on the system. It is clear from both literature and the initial model results of Phase 0 that Bardawil Lagoon currently does not function as a morphologically stable tidal inlet system, as sedimentation occurs in both inlets. The water exchange between the Mediterranean Sea and Bardawil Lagoon is restricted by the inlets, which is indicated by the difference in tidal elevation on both sides of the inlet. Both inlets are positioned near the unstable equilibrium point on the Escoffier curve, indicating possible closure of the inlets in the future. Hence, interventions are required to establish a morphologically stable lagoon inlet system. By applying the proposed designs in Phase 1 and Phase 2, the limitations on the incoming tide shift from the inlets to the inner basin induces friction, thus removing the inlets as limiting factor. Moreover, taking into account both the prevailing winds and high evaporation effects, the total system is classified as having a sediment exporting character after Phase 2. High evaporation rates have a significant importing effect on the sediment transport character of the inlets. However, after Phase 2, these effects are reduced by a factor 3-5 compared to Phase 0, depending on the wind. The new cross-sectional area design also results in both inlets being positioned near the stable equilibrium point on the Escoffier curve after Phase 2, which is supported by the sensitivity analysis. Hence, it is concluded that the proposed adaptations achieve the goal of developing Bardawil Lagoon into a morphologically stable inlet system. The study provides good insight into the effect of system interventions on the morphodynamic stability of the inlets as well as the flow dominance regarding those inlets. It is recommended to construct a validated morphological 3D model which can provide insight in the long term response of the system to those adaptations. ... Read more

This report is written with the aim to evaluate a possible port expansion in the port of San Vicente, Chile. In order to achieve this a thorough analysis on the port operations, hydrodynamical analysis using Delft3D and a bottleneck analysis on the infrastructure have been executed. A preliminary design for the port expansion is created. This design focuses on the land reclamation, the new revetment and the new port layout. ... Read more

Nowadays, conceptual breakwater layout design mostly relies on experience and expert judgement, making it complicated to demonstrate that an economic optimum has been reached. This stresses the need to develop a tool that is able to establish the economically most attractive breakwater layout for a certain set of requirements and site-specific data. This study provides a proof of concept for a generative breakwater layout design tool, applicable to port projects all around the world. This is accomplished by investigating the most suitable optimisation method, by setting up a universally applicable methodology for the determination of the economic optimum and by establishing a robust and flexible model set-up. By validating it against a real case, the parametric model consistently comes up with breakwater layouts having cost estimates that are located within the desired accuracy range for the conceptual design phase. In addition, the parametric model is flexible, as it is able to efficiently deal with changes in design requirements and future port developments, therewith living up to modern design standards. In this way, client expectations are more likely to be met, leading to a spiral of increasing trust between the involved parties in an early design stage. ... Read more

Growth of world population, sea level rise, land subsidence and climate change gives new challenges for the present and the future. A new innovative approach of engineers is needed to reach socio-economic development with care for the environment. In the Netherlands, an EcoShape consortium is initiated where multiple experts came together from the Dutch private and public sector. In this consortium governmental organisations, knowledge institutes and business companies are involved to search for adaptable and sustainable engineering solutions to exploit and promote the ‘Building with Nature’ program. The main goal is to move from building in nature towards building with nature, using the natural forces present in the system.

Chile has shown interested in the Dutch Building with Nature program and the question raised whether a similar concept could be introduced in the country. Therefore, the organisational structure of the Chilean water sector related to coastal engineering is investigated in this research, as well as several case studies are used to illustrate the potential of Building with Nature in Chilean projects. These projects are the coastal erosion in Pichilemu, a port expansion in San Antonio and coastal erosion in Los Vilos.

The Chilean coast shows in different aspects a very dynamic behavior. For the design of a coastal structure it is important to understand this dynamic behavior and the possible consequences. In addition, the study concluded that Chile is a very privatized country which is important to consider when applying Building with Nature into coastal projects. The privatization has the consequence that a substantial amount of stakeholders need to be involved in the projects also funding can be a challenge.

In general, the conclusion can be drawn that there is lack of information on the coastal characteristics in Chile. More data needs to be conducted to implement trustworthy Building with Nature designs. Additionally, one could state that there is a communication gap between the governmental parties as the Dirección de Obras Portuarias and Ministerio de Obras Públicas and the local parties involved in coastal projects. This is important to solve, as these parties needs to be involved in all coastal projects. Another outcome of the case studies is the absence of an environmental vision for most of the initiated coastal projects investigated and the absence of a long term vision of coastal management.

Meeting with various engineering consultancy firms showed the presence of a strong incentive to enlarge the consciousness on the environmental and societal aspects in Chile, and the ambition for a more co-creative and multidisciplinary design approach. Arcadis Chile has shown interest to establish a platform to introduce the Building with Nature approach in Chile. Together with the Universidad de Valparaíso, Arcadis Chile can be the initiator for the implementation of the philosophy and the increase of awareness among other important actors in the water sector.
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The beach adjacent to the Tasikoki Wildlife Rescue and Education Centre is one of the many beaches worldwide suffering from coastline recession. This loss of coast has a negative impact on the environment, local society and ecology. In general, shoreline retreat is caused by sea level rise (SLR) and erosion. The main objective of this research is to determine which factors are causing recession at Tasikoki beach and consequently which solution would be best in terms of mitigating coastline recession and protecting the hinterland from flooding. A Building with Nature (BwN) design philosophy has been considered to utilise natural processes instead of traditional ones, creating benefits for society and nature. Additionally, a model will be created in Unibest to substantiate and test the final solution.
The research first aimed to describe the coastal characteristics, ecosystem and societal system of the Tasikoki coast. This mainly consisted of a desk-study which was based on literature, but also of examining the surroundings and talking to locals. This study revealed amongst others the significant contribution of climate change on the shoreline retreat at Tasikoki beach.. Among the stakeholders, a major blocking power is absent. Nevertheless, an engagement plan is written to explain the local fishermen how they will benefit from the potential solution in order to prevent resistance. After gathering this general information to form a first impression, more location specific data was required to draw conclusions and setup the Unibest model. Every part of the required data has their own measurement method or source, using handmade measuring equipment, sonar GPS, sediment sieves and data retrieved from wind and wave models.
After a thorough analysis on the wave and wind climate and the surroundings of the Tasikoki coast, it could be concluded that the dominant wave direction is coming from a direction of 164˚ north. This determines the dominant sediment direction, which is thus propagating northward along the shore. Next, the direct coastal retreat due to SLR was calculated by using the Bruun-rule. Based on calculations and aerial image analyses, it was concluded that the two tidal inlets present at the Tasikoki coast play an important role in the erosion patternThe four main nearshore (CST) processes impacting the Tasikoki coast are wave impact, long waves, turbulence and avalanching/sliding. During the research, multiple possible solutions have been investigated which could mitigate the coastline recession. Based on a multi-criteria analysis, it was decided that a Biorock-based solution would suit the Tasikoki case best. This is a permeable submerged breakwater with a low current running through a steel frame to dampen waves and enhance nature at the same time.. A submerged breakwater was modelled in Unibest at Tasikoki beach. The result was positive. The structure traps sediment and causes more accretion along the coast than the length of the structure itself; functioning like a ‘sand engine’. At last a detailed implementation and monitoring plan was written, multiple scenarios are considered to make the solution more future-proof. ... Read more

Storm safety and durability of touristic destinations is of utmost importance in Cuba, considering high stakes regarding life and capital invested in the development of the touristic sector. This twomonth research focuses on one of the largest Caribbean beach tourism hotspots found in Varadero, Cuba.

Tourism along the Hicacos peninsula has been on the rise and will continue to do so. The Oasis beach hotel is capitalizing on this trend by building a larger new hotel. However, no characteristic flat white coral beach is present in front of it. Tourist demand is greatly driven by the presence of such a beach. Year-round erosion was verified to be partly caused by a blocking of longshore sediment transport.

The local harbour groyne at the eastern beach section was found to be responsible for this but may not be adapted, as it is a necessity for the harbour entrance. Demolition of existing hydraulic structures, construction of a groyne at the westward boundary and sand nourishing are proposed as a zero-solution to ensure sufficient beach width (40 metres) at the 800-metre coastal segment.
Durability is not achieved through this zero-solution as the average lifetime between maintenance nourishments is smaller than one year.

This result shows that successful development of the Oasis beach sector can only be achieved by considering cross-shore erosion processes as well. An important aspect of the cross-shore transport was expected to be the effect of tropical storms on Oasis beach. To ensure the safety of tourists in storm conditions, an assessment of the infrastructure was required.

A multidisciplinary path was chosen to ensure safety of inhabitants, tourists and capital, especially during hurricanes. Flood safety, coastal engineering, transport and infrastructure form the core pillars of the research. Two distinct events were simulated to determine the morphodynamical response of the Oasis beach, namely hurricanes Wilma (2005) and Irma (2017). Both affected the northern coast of Cuba greatly, but passed Varadero from opposite directions. A general hurricane scenario was tested in evacuation assessments of the entire peninsula, which has just one exit road. Furthermore, the capacity of the current evacuation scheme was projected on the expected population and tourists visiting the peninsula in 2048.

Proposed coastal solutions were the construction of a submerged breakwater along the entire length of the beach, an artificial reef or a combination of the two. Normal, cold front and hurricane conditions were imposed upon these structures using XBeach software to test their performance. The subsequent infrastructural safety of the hinterlands was modelled using Simio software.

Results yielded good performance of the artificial reef against structural erosion from both the normal north-eastern wave climate and the northern cold front waves. The submerged breakwater performed better in hurricane conditions though extension of both groynes was found necessary to keep sediments within the Oasis beach system.

A multi criteria analysis was used to determine the best coastal intervention given the project requirements. Initially, no financial motives were used to determine the optimal solution. The results of this analysis stated a preference for the installation of an artificial reef. Its added recreational value was not quantified and thus not discounted from the initial investment. In detailed design, cost estimations of all viable design alternatives showed that the rtificial reef was also a relatively affordable option.

The final recommended design that ensures beach durability thus consists of: demolition of weathered hydraulic structures, western groyne placement, initial nourishment, artificial reef deployment and maintenance nourishment for a 30-year lifetime. A modelling of the definitive design with, also including the vegetation of the dunes indicated the Oasis beach section to be flood safe.

The total cost of this intervention amounts to approximately $900,000 and takes 28 months to complete. If monitored well, the artificial reef will increase its coastal defence capacities and functionality is expected to exceed the 30-year lifetime.

Recommendations regarding storm safety also include the evacuation process of tourists during the extreme hurricane conditions, on which the coastal design was based. Various projections of the growth of the number of tourists on the Hicacos peninsula have been simulated in a Simio evacuation transport model. The model indicated that even for the largest projected growth of tourism in Varadero, the infrastructure suffices and using a 50:50 ratio between evacuees being transported in buses and cars, it is possible to evacuate the peninsula in twenty-four hours.

To be able to evacuate using this optimal ratio, an increase in car ownership in Cuba is required before 2048, as a shortage exists in the current situation. Therefore, the peninsula is still considered storm-safe, but monitoring of the actual increase in tourists is advised.

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Terminos Lagoon is the biggest and ecologically most important fluvial-lagoon system of the southern Gulf of Mexico. Rivers, sea and meteorology all influence the lagoon, variable over the year, resulting in a complex situation. To protect this area, it is crucial to know how different hydrological processes, hydrodynamic processes and spatial characteristics influence each other in this context. Using a multidisciplinary approach, this research focused on the question: What is the influence of hydrological and hydrodynamic processes on spatial characteristics of Terminos Lagoon, now and in the future? The study has shown that evaporation has a larger part in the water balance during dry season, where during other seasons the water balance is similar to the annual mean. It is found that the western part of Terminos Lagoon shows different characteristics
than the eastern part, as river discharge plays a larger role in the western part of the lagoon. Secchi depth, temperature, dissolved oxygen, sediments and salinity are all different here compared to the eastern part of the lagoon. Salinity and river discharge, as well as air and water temperatures, show to be highly correlated. A tidal watershed divides the lagoon in two approximately equal areas, following the mentioned separation of east and west. Residual currents flow along the boundaries of the lagoon from east to west. A circular
residual current in the lagoon is observed near the Puerto Real inlet in created temperature and Secchi depth maps. Nortes season shows highest salinity and lowest Secchi depths, where dry season shows lowest salinity. Both inlets are expected to sedimentate and sediments outside the lagoon move westward. Climatological influences are uncertain, though likely effects are increased water temperature, salinity, flushing time and a decrease in residual current. Mentioned effects are likely most noticeable in the eastern part of the lagoon.
Further research is necessary to achieve ecological goals in the region. ... Read more

The reach of the Magdalena River around the city of Barrancabermeja experiences large issues concerning its navigability since the construction of the Yondó Bridge. The purpose of this study is to investigate possible causes of this poor navigability and to come up with an improvement to the current situation. The influence of bars and scour holes around bridge piles are seen as hypothetical problem causes. A bar mode analysis shows that, for the examined river section, the river contains one alternate bar over the years. It is plausible that the construction of the bridge has induced changes in flow conditions in such way that the original alternate bar started to erode and eventually totally disappeared. Therefore, it is highly possible that the construction of the bridge forms the main reason for the shift of the thalweg. The scour holes around the piers of the Yondó Bridge that were approximated by the empirical method of Melville and Coleman. These scour holes are incorporated in the Delft3D-model to assess their influence by adapting the initial bed elevation profile. From the model simulation it turns out that the presence of the holes does result in more erosion in the vicinity of the bridge.

Three possible solutions (null-solution, groynes and guide bunds) have been weighed using Multi-Criteria Analysis. Based on this analysis the guide bunds appeared to be the most suitable solution. The structure was implemented in the Delft3D-model and some additional simulations proved that the effect of this structure on the hydro and morphodynamic conditions in the river is twofold. First, the guide bunds improve the distribution of the flow over the cross section of the river. More flow is forced through the right side and indeed the flow velocities turn out to be higher at that location. Moreover, the flow velocities on the left side decrease, as expected. However, the structure has an opposing effect on the cumulative erosion and sedimentation. More sedimentation takes place at the right side of the channel, whereas the left side of the channel gets deeper. It can be concluded that the best way to improve the situation in Barrancabermeja, is the construction of a guide bund structure in the vicinity of the Yondó Bridge. However, more detailed (physical) model tests should be performed to gain better insight in the effect of the guide bunds.
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