| 06 Feb 2026
Human-Centred Design Approaches to Tsunami Mitigation under Sea Level Rise in Kesennuma, Japan
Abstract. Human-centred design (HCD) is increasingly prioritised as studies show human experience is critical in infrastructure use, and recent policies call for more socially responsive design. Tsunami impacts intensify as sea level rise (SLR) raises baseline water levels and reduces existing defence effectiveness, yet HCD informed approaches are rarely tested under projected SLR. Based on identified infrastructure preferences in Kesennuma City, Japan, we develop three multi-layered defence configurations: an environmentally integrated eco hybrid system (Design 1), a discreet open feeling barrier system (Design 2), and a reinforced high-performance system (Design 3). Using TUNAMI-N2 numerical modelling, 150 simulations combine three tsunami sources, five SLR conditions, and five defence states. Results for inundation extent, fatality rates, and economic loss show a consistent hierarchy: Design 3 achieves the strongest containment, while Design 2, which more closely aligns with residents’ preferences for openness and access, delivers near equivalent reductions typically within 10–15 percent. Design 1 provides only limited hazard reduction and is unsuitable as a standalone mitigation system. We show that HCD informed configurations can deliver strong technical performance and support a shift toward socially integrated, multi-layered tsunami protection under rising sea levels.
Review of the paper entitled “Human-Centred Design approaches to Tsunami Mitigation under Sea Level Rise in Kesennuma, Japan” by Hayley Leggett and co-authors.
General comments:
This paper outlines a review of a numerical study to test the sensitivity of physical countermeasures for combined tsunami and SRL impact in Kesennuma. It takes into account possibilities of softer measures through to so-called Human-Centered Design (HCD) approaches. Based on my reading of the paper, the focus is more on testing different technical solutions than on the HCD itself. It might be that a change in the title could be worthwhile to reflect better the scope of the work. I found that the topic and work may provide a valuable addition to the tsunami community, but my conclusion is also that major revisions are needed before the paper can be considered for publication. The main comments are connected to limited uncertainty treatment for the vulnerability, implying that some parts needs to be entirely re-written. Below, I outline the main suggestions for improvement points. Because several sections needs large revisions, I refrained from commenting in detail the later section of the manuscript.
The loss estimation part embeds very large uncertainties that are hidden in the analysis. The analysis includes deterministic loss estimation in Tables 2 and 3 for fatalities and economic loss in particular. These can somehow be interpreted as deterministic vulnerability functions, and mimics an engineering approach. However, our understanding of tsunami vulnerability, and tsunami fatalities in particular, is very limited. The experience from Japan provides only one datapoint, but it will depend on many factors such as time of the day, status of early warning, change in situation since 2011 etc. Hence, presenting the loss analysis without any uncertainty treatment can be greatly misleading. In particular, the fatality is not well understood, and the fatality estimations can be misleading or misinterpreted. Therefore, the methodology description and related results section need a major overhaul. The main comment is that fatality quantification is suggested to be removed. For the remaining part, the discussion related to the losses should have a much greater emphasis on the large uncertainties involved, and should be rewritten to make the uncertainty aspect clearer both in the methods, results, and discussions.
The analysed earthquake scenarios are too few and quite limited in spanning the wealth of potential sources that is needed to fully understand the variable response of the mitigation measures. I would suggest that the authors provide a short discussion on how other sources, for example larger megathrust sources from PTHA (e.g. Behrens et al., 2021) would be expected to influence the results. In particular, an analysis of how differences in wavelengths and offshore amplitudes (and potentially their link to focal mechanisms) affects the effectiveness of the mitigation.
Further, it is difficult to assess the effectiveness of all the physical countermeasures without testing them against model results without any physical protection. This would make the results much more transparent, and illustrate better the effectiveness of Designs 1,2, and 3, as it would constitute a sort of normalization. So, I would strongly recommend adding this to the study if possible.
Reading the manuscript I found many repetitions, in particular related to the HCD procedure in the introductory sections. These repetitions make the scope of the paper more difficult to follow. Hence, the manuscript could benefit from being tightened up. Moreover, it seems like the scope is mostly related to testing numerically how three different design methods influence physical protection rather than the HCD itself, which serves more as a background. Hence, I would recommend to shorten the introduction related to this background and have a stronger focus on the numerical testing.
An open question is finally if such defense structures also can be tested in the laboratory. A short discussion related to this would be valuable.
Line by line comments:
L25: Please add references to SRL studies such as Li et al. (2018), Dura et al. (2021), Sepulveda et al., (2021).
L30: Unclear what is meant by this statement “have shown limited adaptability to changing environmental baselines”, please rephrase.
L34: The reference to “empathy” sounds subjective in a science setting, is it possible to elaborate more what this would concretely imply for the HCD?
L37: meaningful --> effective
L40-45: Lots of focus on the local perception here, but the physical protection context is lacking.
L45: The term “user experience and local values” is vague, what does it mean concretely?
L56: Please define the concept “multi-layered design” as it used throughout the manuscript.
L65: The wave energy is not changed, only the focussing of it. Please rephrase.
L69: revise “most catastrophic” to “most catastrophic event in history”. Please specify that you are talking exclusively about its impact on Kesennuma.
L72-73: Was the design also done towards more moderate local earthquakes (e.g. the M8.4 discussion) in addition to 1960 etc?
L76 and onwards: On what PTHA design basis? Please give reference. I would suggest a short review of PTHA methods here (e.g. Grezio et al., 2017, Davies et al., 2018, Behrens et al., 2021) and outline limitations of the scenario approach chosen here (see discussion above). The derivation or relationship of the scenarios from the PTHA should also be outlined.
L106: The meaning of the sentence is not completely clear. Does this imply that the countermeasures were considered less effective than in comparable locations along the Tohoku coast?
L107: Please add a reference after “safety standards”
L135 and onwards: Looks like this is partly discussed above. Since it is mainly background information, please consider shortening.
L146: differing --> different
154: You say these barriers are effective, but no reference or quantitative measure is given, please add a reference.
L159 and onwards: Sentences starting with “The rationale” seems essential to the study and might be moved up front.
L176: the research --> this research
L187: Sentence starting with “Consequently…” should be in the introduction, but this motivation it is also partly duplicated elsewhere.
L250: Why discuss the time step when describing the general model? It will depend on the grid size and CFL number.
L255: Are the structures rather embedded into the topography / DEM?
L259: The offset of the model towards real events will really depend on the source and event itself. Perhaps it is better to report on the validated benchmark cases?
L290: As mentioned in the general comments, I found the set of sources very limited to thoroughly test countermeasures. This limitation should be discussed better.
L292: Missing reference
L300 and onwards: Here you discuss general properties of TUNAMI-N2, but this should not enter here, but rather in the general model description above.
L374: The fatality model gives the impression that a deterministic analysis can be made for estimating the mortality losses, but it is given without proper scientific backing. There is also no uncertainty discussion here. Mortality will depend on many factors such as event time, experience etc, early warning. Hence, I cannot recommend keeping this section in the manuscript, and think it should be entirely removed.
L410: Uncertainties should be discussed.
L415: Reference missing
L450: Sentence “This approach yields…” please delete, it is not really backed up anywhere (how can it be reproducible for instance?).
Figure 9: Technically speaking the lon-lats should be “easting - northings” as they are in meters and not in degrees. It is unclear what current defenses refer to, please add this to the caption.
L481: Please fix cross references
L483: “conditions intensified” --> “intensities were increased”
Fig10: Hard to interpret really how good and cost effective these measures are without a “no-countermeasure” reference model.
Section 4.3: I strongly recommend removing this from the paper without a much better uncertainty analysis.
Figure 12, 13, 15: Unclear which scenarios that are used here.
L578: The lack of sensitivity to the fatalities indicates that the uncertainties are supressed in this analysis, which is another reason why I suggest to take it out of the study.
References:
Behrens, J., Løvholt, F., Jalayer, F., Lorito, S., Salgado-Gálvez, M. A., Sørensen, M. et al. (2021). Probabilistic tsunami hazard and risk analysis: A review of research gaps. Frontiers in Earth Science, 9, 628772.
Davies, G., Griffin, J., Løvholt, F., Glimsdal, S., Harbitz, C., Thio, H. K., et al. (2018). A global probabilistic tsunami hazard assessment from earthquake sources.
Dura, T., Garner, A. J., Weiss, R., Kopp, R. E., Engelhart, S. E., Witter, R. C., et al., (2021). Changing impacts of Alaska-Aleutian subduction zone tsunamis in California under future sea-level rise. Nature communications, 12(1), 7119.
Grezio, A., Babeyko, A., Baptista, M. A., Behrens, J., Costa, A., Davies, G., et al., (2017). Probabilistic tsunami hazard analysis: multiple sources and global applications. Reviews of Geophysics, 55(4), 1158-1198.
Li, L., Switzer, A. D., Wang, Y., Chan, C. H., Qiu, Q., & Weiss, R. (2018). A modest 0.5-m rise in sea level will double the tsunami hazard in Macau. Science advances, 4(8), eaat1180.
Sepúlveda, I., Haase, J. S., Liu, P. L. F., Grigoriu, M., & Winckler, P. (2021). Non‐stationary probabilistic tsunami hazard assessments incorporating climate‐change‐driven sea level rise. Earth's Future, 9(6), e2021EF002007.