I frame my research around the multifaceted interactions mediated by the coastal geoenvironment. I conceptualise coastal zones as interfaces characterized by dynamic land–ocean and surface–subsurface interactions. Groundwater flow and solute transport through the subsurface provide key physical pathways that connect these domains and shape their interactions.
My central aim is to elucidate the physical processes underlying these interactions. In particular, I investigate how geological heterogeneity and transient external forcing shape flow and transport in porous media [1–3], and how coupled surface–subsurface hydrological systems in coastal environments respond to storm surges [4,5]. Motivated by real-world phenomena, I develop conceptual models that isolate the dominant physical processes and capture essential system characteristics. Through numerical modelling, complemented by concepts from nonlinear dynamics and stochastic processes, I investigate how particular phenomena emerge and under what conditions they occur. Beyond explaining individual phenomena, I seek to identify underlying mechanisms that help advance existing theoretical frameworks and yield generalisable physical insights.
In parallel, I translate these insights into models for practical applications, including groundwater resource assessment, flood prediction, and climate adaptation [1,5]. Using simple heuristic expressions and dimensionless numbers, these models capture governing relationships while maintaining physical consistency and limiting data requirements and computational costs.
I also regard coastal zones as interfaces between natural systems and human societies. Climate change alters groundwater availability, with consequences for human livelihoods. Social institutions, cultural practices, and decision-making processes in turn shape access to groundwater resources and influence adaptation pathways. To better understand these human–nature interactions, I seek to bring physical understanding into dialogue with diverse knowledge systems through collaboration with a broad range of stakeholders. My ultimate aim is to advance transdisciplinary research that contributes to sustainable water resource management and climate adaptation.
References
[1] Tajima et al. (2024). Advances in Water Resources, 189, 104714. Link[2] Tajima & Dentz (2025). Advances in Water Resources Link
[3] Tajima & Dentz (2025). Water Resources Research, 61, e2025WR040620. Link
[4] Tajima et al. (2023). Water Resources Research, 59, e2023WR034762. Link
[5] Tajima et al. (2026). Water Resources Research, 62, e2025WR042142. Link