2021 Fiscal Year Research-status Report
Quantitative Evaluation of Coastal Forests on Natural Disaster Mitigation - Considering the Complexity of Vegetation Structures
| Project/Area Number |
20K14838
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| Research Institution | Kyoto University |
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Principal Investigator |
張 哲維 京都大学, 防災研究所, 特定助教 (20866826)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 海岸林 / 波浪減衰 / 沿岸災害 / 気候変動適応策 / マングローブ / Eco-DRR / ブシネスクモデル / 水槽実験 |
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| Outline of Annual Research Achievements |
Coastal forests, a sub-type of Ecosystem-based solution to Disaster Risk Reduction (Eco-DRR), can protect the shorelines against coastal hazards. However, the lack of quantification of their capacity limits the practical application. This study investigates the effectiveness of mangroves and pine trees, the two main coastal trees in Asia-Pacific areas, on wave attenuation considering their unique morphologies, via field survey, laboratory experiment, and numerical simulation.
This year, we analyzed the geometrical features measured in the fields and proposed the relationships between the features characterizing vegetation morphology, which will be used to parametrize vegetation effects in the numerical model. In addition, we conducted laboratory experiments on 3D-printed mangroves and idealized pine trees. In the experiments, we applied the direct force measurement to study the resistance induced by vegetation, such as 3D mangroves and their roots, and build up empirical relationships between
force coefficients and dimensionless flow parameters. Continuing the development of the Boussinesq-type model, we incorporated vegetation-induced resistance as a Morison-type force whose drag and inertia coefficients were directly determined based on the aforementioned empirical formulas. We tested the performance of the numerical model with the experimental data. The sensitivity test of the force coefficients and the related wave damping is currently ongoing. To generalize the empirical formulas to a wider range of morphologies, we prepare to conduct more experiments on 3D mangroves.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The numerical model has been developed with the incorporation of vegetation effects. The model was tested using experimental results. The field data of the morphological features of mangrove roots has also been analyzed and published in Frontiers in Built Environment, which provides a base of parameters for numerical simulation. More laboratory experiments on 3D-printed mangrove models are prepared to conduct. The experimental results on wave attenuation and vegetation-induced resistance will provide more dataset to complete the development of the Boussinesq-type wave mode and model tests. The progress meets the middle-stage objectives as planned.
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| Strategy for Future Research Activity |
Expanding and generalizing the developed numerical model requires a more comprehensive dataset of vegetation morphology, such as the representative morphological characteristics of mangroves from laboratory and field inputs. Laboratory tests resembling complicated field conditions, especially the variety of mangrove roots, will be useful to expand the empirical formulation for the parameterization of mangrove-induced resistance in numerical simulation. More experiments with different configurations will be conducted next to investigate vegetation-induced resistance and the related wave attenuation. A base of parameters for the numerical model will be established based on laboratory and field outputs.
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| Causes of Carryover |
The remaining budget for FY2021 and the fund granted for FY2022 will be used for laboratory experiments, such as the setup of instrumentation and experimental apparatus, and the purchase of computers for data analysis.
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