Yokohama National University/ College of Urban Sciences/ Institute of Urban Innovation

I will continue to work on coastal engineering, especially on the problem of wave characteristics and sand drift in coastal areas, and on the construction of a model of beach topography change. I will also gradually conduct research on coastal environments.

Research keywords:
Sediment transport in and out of the surf zone and swash zone Water content in a sand layer, pore water pressure Berm, outer bar Wave, shore noise Coastal Vulnerability Tsunami scour

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Sediment transport and topographic change

A large amount of bottom sediment within the surf zone moves due to floating sediment caused by wave breaking and turbulence. This is also an area where topographic changes occur actively. We have been studying the three-dimensional fluid motion during wave breaking, the local and intermittent nature of sediment flotation, long-term variation of the shoreline position, and topographic change modeling in the upwelling area. Using a high-speed camera, we are also studying the effects of pressure fluctuations in sand layers on sediment dynamics using pore pressure gauges and understanding the fluid field and sediment transport dynamics.

Examples of research topics
* Generalization of geomorphic change models focusing on the erosion of berms
* Long-term modeling of geomorphic change in upwelling areas
* Relation between pressure fluctuations, water content, and suspended sand volume in bottom sediments

Previous studies
* Study on the rate of shoreline advance
* Study on the effect of bottom pressure fluctuation on the amount of sand transported upstream
* Characterization and statistical modeling of vertical pressure gradient under the bottom
* Experimental study on the constructability of structures in front of the beach cliff

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Coastal Environment

We also research waves and currents in coastal areas. We are also improving numerical models using undertow data obtained from field surveys, clarifying the characteristics of beach cusp formation, and studying microplastics.

Examples of research topics
* Characterization of microplastic (MP) content and its dynamics in the tourist beaches
* Characterization of cusp topography and prediction of shape change
* Elucidation of the effects of tides and topography on return currents and improvement of models

Past Research
* Research on flow change in Lake Sagami focusing on discharge
* The comfort of coastal environmental sound
* Disaster prevention in coastal areas using mangroves
* Research on the understanding of oceanographic information using wave sounds
* Research on flow fluctuations in bays during strong winds (joint research with Kyoto University and CRIEPI)

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Coastal Disaster Prevention

We research appropriate countermeasures against natural disasters that occur in coastal areas due to high waves, wind protection, etc. We also conduct research on the performance evaluation of coastal structures. For example, we estimate wave fields using coastal environmental data, calculate storm surge inundation using numerical simulations, and evaluate the performance of coastal structures. We also collaborate with other fields, such as those related to the appropriate evacuation of residents.

Research Theme
* Generalization of on-site wave estimation method using IC recorder
* Study on the vulnerability of sandy beaches in multi-hazard conditions
* Development of Beach Vulnerability Index (BVI) and CVI
* Improvement of the accuracy of the model of scour behind structures caused by tsunami overtopping

Past Research
* Proposal of measures to promote evacuation during tsunamis
* Video analysis of the tsunami caused by the Tohoku-Pacific Ocean Earthquake
* Study on the Determination Method of Bridge Girder Run-Out Hazard Using Numerical Wave Channel
* Damage of the 2004 Indian Ocean Tsunami in Indonesia and Sri Lanka

Publications

The most recently published papers are listed below. For other publications, please refer to the Yokohama National University Researcher data base and/or Research Gate.［YNU Data Base］［Research Gate］

1)　Suzuki, T., Tajima, K., and Jayaratne, R. (2022). Laboratory modelling of vertical sediment mixing in the surf zone. Coastal Engineering Journal, 64(4), 619-629. doi.org/10.1080/21664250.2022.2143750
2)　Borribunnangkun, K., and Suzuki, T. (2022). Statistical modeling of undertow on a natural beach. Coastal Engineering Journal, 64(4), 489-505. doi.org/10.1080/21664250.2022.2122374
3)　Gelfi, M., Suzuki, T., and Jayaratne, R. (2022). Sediment size effect on the landward coastal structure scour prediction due to tsunami. Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 78(2), I_469-I_474. doi.org/10.2208/kaigan.78.2_I_469

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