Dear colleagues
I kindly would like to thank you for submission of your manuscript to NHESS. During the open discussion phase, we received one SC and two comments of referees. As you have seen, and also answered publicly, all of the comments are of minor type and relate to some clarification of methods used and conclusions drawn.
I would like to shed light on another important item: while it is – correctly – reported that increasing risk has at least two root causes (effects and impacts of CC as well as population dynamics in flood-prone areas) I kindly would like to suggest that you add one or two statements on the latter. Also in Northern Italy we do have distinct regions with decreasing population, and some others with population increase, which makes the general conclusion that values in flood-prone areas increase impossible (this is valid for many areas, but not for all). Moreover, as recently shown for Austria and Switzerland (Fuchs et al., 2015; Fuchs et al., 2017; Röthlisberger et al., 2017), elements at risk exposed to flood hazards are not always/not necessarily of the same building type and therefore exposure is highly dynamic in space and over time. To give an example, for Austria, it has been shown that a relatively higher share of buildings exposed to flood hazards in the lowlands belongs to the category of commercial buildings, while in the upper catchments this share is higher for residential buildings and hotels/buildings of the tourism industry. Consequently, if we include “population dynamics” or “dynamics in exposure” into a somehow dynamic risk concept, this should be mentioned. Obviously this does not necessarily mean that I expect a reference to my own works, this is only for illustration – there are also other works centered on these issues available.
Moreover, some of the items described in section 2 (methods) have overlaps with a paper by Metulini and Carpita (2020). As this concerns mainly the methods section, I personally can accept it (and also according to the overall NHESS guidelines this is somehow ok) but I kindly would like to ask you to change wording a bit so it is not 1:1 the same text.
Hence, I kindly would like to encourage you to undertake necessary revisions, as indicated by the two referees, the scientific comment, and by me in this decision letter. I strongly believe that your piece of work is timely and adds some interesting and novel aspects to the overall discussion of flood hazard risk management.
I am looking forward to receiving your revised manuscript.

Kind regards, Sven Fuchs (Editor NHESS)

References mentioned:
Fuchs, S., Keiler, M., and Zischg, A.: A spatiotemporal multi-hazard exposure assessment based on property data, Natural Hazards and Earth System Sciences, 15, 2127-2142, https://doi.org/10.5194/nhess-15-2127-2015, 2015.
Fuchs, S., Röthlisberger, V., Thaler, T., Zischg, A., and Keiler, M.: Natural hazard management from a coevolutionary perspective: Exposure and policy response in the European Alps, Annals of the American Association of Geographers, 107, 382-392, https://doi.org/10.1080/24694452.2016.1235494, 2017.
Metulini, R., and Carpita, M.: A spatio-temporal indicator for city users based on mobile phone signals and administrative data, Social Indicators Research, http://doi.org/10.1007/s11205-020-02355-2, 2020.
Röthlisberger, V., Zischg, A., and Keiler, M.: Identifying spatial clusters of flood exposure to support decision making in risk management, Science of the Total Environment, 598, 593-603, https://doi.org/10.1016/j.scitotenv.2017.03.216, 2017.

Dear colleagues

I kindly would like to thank you for the minor revisions undertaken, and also for the comprehensive answers to the points raised by the referees.
I am happy to inform you that the manuscript has been finally accepted for publication in NHESS.
Again, thanks for your patience during manuscript evaluation.

Kind regards,

Sven Fuchs, Editor NHESS