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Green protecting green : Optimizing permeable structures in mangrove restoration with an analytical model
Jacobs, Dimphy (2025) Green protecting green : Optimizing permeable structures in mangrove restoration with an analytical model.
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| Abstract: | In previous decades, there has been a global reduction of mangrove areas due to human influences. To bring back some of the lost mangroves, mangrove restoration projects are being implemented. A frequently used method to do so is the use of permeable dams. This method is also used in the Demak Region in Indonesia. The main objective of this research is to determine to what extent the design of permeable structures used in mangrove restoration projects can be optimized using a model that computes the depth-variable wave energy transmission of different design options. The ‘optimal’ dam design depends on limited material usage and a minimum transmitted wave energy. An analytical model is developed that calculates the depth-variable wave energy in the water column and the total wave energy. The developed model focuses on intermediate wave conditions. This way, it is observed at what water depths the wave energy should be ‘dissipated’ to meet the maximum energy that allows for mangrove development. Furthermore, horizontal elements are simulated in the model. These represent the permeable structures, represented as horizontal bamboo beams attached to vertical bamboo poles. Four design options with varying placement of the horizontal elements relative to the water level are simulated. For each design option, the wave energy reflection, wave energy dissipation, and the resulting transmitted wave height are examined. The horizontal elements are represented with dissipation, reflection, and transmission coefficients. The maximum wave energy that mangrove seedlings at various ages and for all hydrodynamic conditions can withstand is calculated. This is called the ‘critical wave energy’. It is examined which of the design options reduces the wave height that does not exceed the critical wave energy. The model gives good guidance in choosing and analyzing the implementation of different design options. It is easy to conclude which design option is the most efficient one. At last, the model output is used to determine the optimal design. The Design option where a gap between the seabed and the last horizontal element increases is considered to be the optimal design option. A specific design with specified placements of the horizontal elements is, however, not advised, since it is condition and site- specific. Finally, expert elicitation clarifies the practical applicability of the model in the field. The expert elicitation clarified the practical applicability of such a model in the field. It also helped determine the risks of assumptions and simplifications made. It is recommended to conduct a stability analysis of the structure in further research. Furthermore, it is recommended to implement morphodynamic and socio-economic processes into the model and the design phase. |
| Item Type: | Essay (Master) |
| Faculty: | ET: Engineering Technology |
| Subject: | 56 civil engineering |
| Programme: | Civil Engineering and Management MSc (60026) |
| Link to this item: | https://purl.utwente.nl/essays/106905 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
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