the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 14 Jul 2026
Brief communication: How well are Londoners prepared for flooding? An assessment of risk mitigation actions and a pilot comparison of perceived and modelled flood likelihood
Abstract. Surface water flooding probability in London is high but little is known about how aware Londoners are of their exposure. 183 online survey responses showed large differences between perceived flood likelihood and modelled flood probability for respondents’ homes (where the latter could be confidently determined - full addresses cannot be collected due to ethical constraints, which limited sample size and representativeness): 54.6 % overestimated their flood likelihood, 19.7 % underestimated, and 25.7 % were accurate. Residents in high flood probability locations underestimated their exposure. Self-reported flood probability knowledge increased perception accuracy. Climate change concern was linked to flood probability overestimation and implementation of risk mitigation actions.
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RC1: 'Comment on egusphere-2026-3820', Milad Basirifard, 14 Jul 2026
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- The principal percentages appear to be mathematically incorrect. This is the most serious problem. Table 1 states that the comparison sample contains 183 respondents, including 30 who answered “unsure.” Table 2 nevertheless also totals 183 observations while claiming to classify respondents as underestimating, accurately estimating, or overestimating flood probability. The reported counts are 36 underestimated, 47 accurate, and 100 overestimated, which sum to 183. An “unsure” response cannot logically be assigned an ordered difference of one or more probability bands. The numbers strongly suggest that the 30 “unsure” respondents may have been added to the underestimation group: Table 1 implies only approximately six genuine underestimators, while Table 2 reports 36. Moreover, the diagonal percentages in Table 1 appear to produce approximately 45 accurate responses, not 47.
- Respondents were asked about the general flood risk level where they live, without specifying the source of flooding. However, the authors compare these answers specifically against surface-water flood probability, selected because it was reportedly the highest modelled probability for the retained addresses.
- The government tool requires a full address because flood probability can vary among properties within a postcode. The authors did not collect addresses and instead retained postcodes in which at least 75% of addresses shared a flood category. This does not establish the flood category of a particular respondent’s property. Up to 25% of addresses may still belong to another category, and no evidence is presented showing the expected individual-level classification error. The 75% threshold is arbitrary, and there is no sensitivity analysis using thresholds such as 80%, 90%, or 100%.
- The manuscript highlights that all respondents in the medium- or high-probability categories underestimated their exposure. Yet this claim is based on one medium-probability and four high-probability respondents. Five observations cannot support statements about residents in high flood probability locations, as presented in the abstract. The uncertainty is enormous, and the finding could easily be a sampling accident. It should not appear as a principal conclusion. At most, it may be reported as an anecdotal pilot observation requiring confirmation in a risk-stratified sample.
ReplyCitation: https://doi.org/10.5194/egusphere-2026-3820-RC1 -
RC2: 'Comment on egusphere-2026-3820', John Drury, 02 Aug 2026
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This paper reports a study comparing Londoners’ perception of flood risk in their own area with estimated flood risk in their area. This is an important topic, as there is previous evidence from a range of other threats that members of the public often underestimate risk likelihood. This has consequences for preparedness and interpretation of threat signals. I am less familiar with the specific literature around perceptions of flood risk, but the authors suggest that this may be mixed, which may be due to changing perceptions of climate crisis. For this reason too, the present study has a strong rationale. The authors’ strategy of comparing participant ratings to existing estimates by postcode seems a reasonable one.
Other than for high-risk areas, the finding of over-estimation (in low risk areas) contrasts with findings on risk in the broader literature on public perceptions of hazard risk, where people often believe ‘it won’t happen’ (or ‘it won’t happen to me’). For example:
Atwood, L. E., & Major, A. M. (2000). Optimism, pessimism, and communication behavior in response to an earthquake prediction. Public Understanding of Science, 9(4), 417–432. https://doi.org/10.1088/0963-6625/9/4/305
And
Kinsey, M. J., Gwynne, S. M. V., Kuligowski, E. D., & Kinateder, M. (2019). Cognitive biases within decision making during fire evacuations. Fire Technology, 55, 465–485. https://doi.org/10.1007/s10694-018-0708-0
As the authors acknowledge, however, the sample is small and not necessarily representative of London (let alone other locations). Therefore it seems correct to treat the study as a pilot.
Specific points.
P 2 ‘Given the particular hazard and vulnerability profile in London’
Explain what that is.
Method
- 3 Explain why the sample target was 500. Also this seems to be a total recruitment. What was the useable target for analysis, if any?
Report demographics – ages, gender, ethnicity.
I am not sure that a representative sample is a matter of (large) numbers as the authors imply. Approaching representativeness means stratifying certain demographics. If the larger sample doesn’t do this, it’s still not representative.
Technical corrections
The abstract should not include the point about full addresses not being collected – leave this detail to the main body
I am not sure why method limitations are in the method section. I would expect to see this in the discussion, not here.
Citation: https://doi.org/10.5194/egusphere-2026-3820-RC2 -
RC3: 'Comment on egusphere-2026-3820', Anonymous Referee #3, 07 Aug 2026
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Thank you for the opportunity to review this manuscript. The manuscript presents a brief assessment of how London residents perceive their flood probability and how these perceptions compare with modelled flood probability. Based on an online survey of 469 respondents, the authors investigate the relationship between perceived and modelled flood likelihood, self-reported knowledge of flood risk, climate change concern, previous flood experience, and household preparedness actions. Then, a subset of 183 respondents is used for the comparison between perceived and modelled flood probability. Overall, I found the manuscript interesting and relevant to the field of flood risk management. I particularly appreciate the attempt to compare perceived flood probability with modelled probability, as this provides a useful perspective on the potential mismatch between general awareness of flooding and individuals' understanding of their own exposure. The manuscript also provides some interesting observations regarding the relationship between perceived risk, climate change concern, and preparedness actions.
I believe the manuscript is suitable for publication after addressing a few comments, mainly concerning the interpretation of some results and the clarification of several concepts used in the survey. Given that this is a brief communication, I do not think that extensive additional analyses are necessary. Rather, I think that some statements could be made more cautious and that some aspects of the interpretation could be clarified.
Overall comment
The manuscript provides a useful observation regarding the mismatch between perceived and modelled flood probability. However, I think the manuscript would benefit from a clearer explanation of the practical implications of this mismatch for flood risk management. For example, could the findings suggest a need for more spatially targeted risk communication, particularly for residents who may underestimate their flood probability? A brief discussion of how the observed mismatch could inform risk communication or preparedness interventions would help clarify the practical relevance of the study.
Specific comments
Page 1, Lines 19–22. The statement that "high property prices have led to many basements being converted into flats (apartments) in London" was not completely clear to me. I initially found it difficult to understand the causal relationship implied by this sentence. Do the authors mean that high property prices have created incentives to convert basement spaces into residential units, thereby increasing the number of people and properties potentially exposed to basement flooding? If so, I think this could be stated more explicitly. A brief clarification would help readers understand why this particular characteristic of London's housing market is relevant to flood vulnerability.
Page 1, Lines 28–31. Since the central focus of the manuscript is the perception of flood probability and its relationship with preparedness, I think it would be useful to briefly introduce here the main factors identified in the literature as influencing flood-risk perception and subsequent mitigation behaviour. The authors already cite Taylor et al. (2014) and Lechowska (2022) in this context. A short sentence summarising the most relevant factors would help establish the conceptual background for the subsequent analysis, particularly Section 3.3 on preparedness actions. This does not need to become an extensive literature review, given the brief communication format, but a slightly clearer link between the existing literature and the variables examined in the survey would strengthen the rationale of the study.
Page 4, Lines 99–104. I appreciate the methodological difficulty of estimating modelled flood probability without collecting full addresses, particularly given the ethical constraints described by the authors. I would nevertheless appreciate a brief justification for the 75% threshold used to retain respondents, whereby at least 75% of addresses within a postcode had to share the same flood-probability category. Why was this threshold considered sufficient to confidently assign the modelled flood probability to a respondent? I understand that this may have been selected as a pragmatic criterion to balance sample size and confidence in the assigned probability, but a brief explanation of the rationale for this threshold would help clarify this methodological choice.
Page 8, Lines 215–220. I found the section concerning self-reported knowledge and flood-probability estimation accuracy particularly interesting, but also one of the weaker parts of the interpretation. The manuscript states that accuracy increased from 16.7% among respondents who felt "not at all informed" to 50.0% among those who felt "very well informed". However, the latter category contains only six respondents. The subsequent statement that "this result implies" that greater outreach could potentially improve the low accuracy observed overall seems too strong given this small sample. I would suggest presenting this as a possible trend rather than as evidence supporting the effectiveness of greater outreach. For example, the authors could state that the result "suggests a possible trend" or that it "should be interpreted cautiously given the small number of respondents in the 'very well informed' category." This would make the interpretation more consistent with the evidence presented.
Page 8, Lines 220–221. The authors report no association between previous flood experience and flood-risk preparedness. I found this result interesting because the Introduction identifies previous flood experience as an important indicator of risk-management actions, based on the literature cited by the authors. However, the full cohort included only four respondents with direct experience of flooding and 20 with indirect experience. Therefore, I think this finding should be interpreted very cautiously. In particular, the absence of an identified association in this sample should not necessarily be interpreted as evidence that previous flood experience is unrelated to preparedness. It may instead reflect the very small number of respondents with previous flood experience. A brief clarification of this point would strengthen the discussion.
Appendix, Section A (Climate change concern, Page 9, Lines 260–266). I found the categories "Very concerned", "Fairly concerned", "Not very concerned", and "Not at all concerned" somewhat difficult to interpret because the manuscript does not indicate whether these categories were associated with any specific definitions or were intentionally based on respondents' subjective assessment. If the latter was the intention, I think this could simply be clarified in the description of the survey. Since climate-change concern is subsequently considered in relation to flood-probability perception and preparedness actions, it would also be useful to briefly acknowledge that these self-reported categories may involve some degree of subjectivity or response heterogeneity. I would not necessarily consider this a major limitation, but a brief clarification would help readers better understand how this variable was interpreted.
Appendix, Section B (Page 10, Lines 270–274). The survey includes the response category "Yes, indirectly (nearby area)" when asking about previous flood experience. I think it would be useful to briefly clarify what the authors intended by "indirectly affected", or indicate whether this was left to the respondent's own interpretation. This would help readers better understand how this category was interpreted when discussing the role of previous flood experience.
I hope these comments are helpful in further improving the clarity and quality of the manuscript. I found the study interesting and relevant, and I appreciate the authors' work on this topic.
Citation: https://doi.org/10.5194/egusphere-2026-3820-RC3
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