京都大学 · 環境科学
長谷川研究室では、海岸災害の緩和に寄与するグリーンインフラとしてのマングローブ林の波減衰機能に注目し、実物に近い3Dプリントモデルを用いた実験と数値シミュレーションを融合した研究を推進しています。特に、マングローブの複雑な根系構造が波に与える抵抗力のメカニズムを解明し、波力の定量的評価とその応用に貢献しています。近年の研究では、実験データに基づくモリソン式の力係数の特定や、ボッシネスク型数値モデルへの効果の組み込みにも成功しています。
Figures are computed from collected data and may differ slightly.
Green infrastructure, utilizing coastal ecosystems, provides a nature-based solution to counteract coastal hazards and rising sea level. Coastal forests, a major type of green infrastructure, are recognized as natural barriers against ocean waves. They can attenuate waves, mitigate erosion, and stabilize shorelines. With growing interests in coastal forests and their function of adapting to future risks, many researchers studied vegetation effects in coastal protection. Yet our limited expertise
Abstract This paper studied the interactions between mangroves and water waves through laboratory experiments. Using 1:7 scale 3D‐printed trees based on the scanned image of a typical Rhizophora species, we replicated the root structure of natural mangroves and constructed a model forest. Three arrangements of mangrove models, two model forests of different stem densities and a single tree in isolation, were adopted. To investigate the relationships between mangrove resistance and waves, we appl
An experimental study of water waves through a model mangrove forest is presented in this paper. Instead of using idealized or artificial tree models, 3D-printed mangrove models whose geometric structure was based on a typical mature tree (Rhizophora apiculata) at a scale of 1/7 were adopted in the laboratory experiments. During the experiments, the fluid velocity and forces on the tree model were directly measured, which provided a comprehensive investigation of the wave-induced forces on mangr
In this study, the Boussinesq-type model in Kim et al. (2009)1) was applied with the incorporation of the specific mangrove effects to simulate wave propagation and hydrodynamics in mangrove forests. Due to the depth-integrated assumption in Boussinesq-type governing equations, the mangrove effect was parameterized by the Morison-type formula (Morison et al. 1950)2) as an additional force term. The force coefficients were determined based on the experimental findings in Chang et al. (2020)3), wh
of a Thin Circular Cylindrical Shell, Journal of the Aerospace Sciences, Vol. 28, 1961, pp. 602-609. 7 Agamirov, V. L. and Volmir, A. S., Behavior of Cylindrical Shells under Hydrostatic Dynamic Loading and Axial Compression, Journal of the American Rocket Society, Jan. 1961, pp. 98-101. 8 Bertram, J. E. and Sarachik, P. E., Stability of Circuits with Randomly Time Varying Parameters, Proceedings of the International Symposium on Circuit and Information Theory, Los Angeles, California, 1959, IRE
Abstract Mangrove forests provide effective coastal protection by attenuating wave energy, yet quantifying wave‐vegetation interactions remains challenging due to vertically heterogeneous root structures and variable submergence conditions. This study advances phase‐resolving wave–vegetation modeling by integrating realistic, depth‐dependent Rhizophora apiculata root morphology into a fully nonlinear Boussinesq‐type model. A new vegetation module was developed and implemented in the model, allow
Mangroves, a major type of nature-based solution in the tropics and subtropics, were evidenced capable of reducing wave energy in tsunami and storm events. The typical species, Rhizophora with its complex root system, was found effective in wave attenuation (Tanaka et al. 2007) and was studied experimentally using artificial tree models (e.g. Maza et al. 2019). To investigate the impacts of mangrove roots on water waves at a finer scale, we conducted experiments using 3D-printed models that repl
Abstract The bond stress distributions are first determined around a single cylindrical fiber embedded in an infinite matrix which is subjected to uniaxial tension in the direction of the fiber length. This solution is then extended to the case where the matrix is reinforced by a three-dimensional repeating array of fibers. The effective elastic constants and bond stresses are calculated for various fiber-matrix modulus and spacing parameters. In addition, the effects on the stress distributions
Mangrove forests, featured by the complex root system, were found effective among natural-based solutions in coastal disaster reduction (e.g. Guannel et al. 2016). The prop roots of mangroves have been deemed useful in attenuating waves and were addressed in several recent experimental works using artificial tree models (e.g. Maza et al. 2019). In this study, laboratory experiments were conducted on both model scale and prototype scale using more realistic models. We aim to provide a comprehensi
The linear model on shallow-water wave propagations through a coastal forest has been developed by Mei et al. (2011). In this study, we extend the linear model and consider weakly nonlinear effects. Because of the weakly nonlinear effects, higher harmonics will be generated inside the forest. Wave attenuation is investigated and the new results are compared with those of the linear model. The effects of different physical parameters are also discussed.
In the face of threats posed by intensifying storms and rising sea levels, Natural and Nature-based Features (NNBF) have gained substantial recognition for enhancing coastal resilience. Mangrove forests, among the natural features, have emerged as an exceptional exemplar against coastal hazards. With their complex root systems, mangroves possess the capability to dissipate wave energy, decelerate flow velocity, and mitigate extreme waves and surges. To investigate the impacts of mangrove root sy
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