Exploring the role of risk perception in influencing flood losses over time

Figures & data

Figure 1. Representation of the four myths of nature (or rationalities) according to their main features and their view of nature (after Thompson et al. 1990). (a) risk neglecting; (b) risk controlling; (c) risk downplaying and (d) risk monitoring.

Table 1. Parameters of the socio-hydrological model used in the analysis. The values varying in a range depend on each specific society (see Table 2).

Parameter	Description	Value	Notes
αH	Related to the flood depth–damage curve	10 m	Penning-Rowsell (1996)
ξH	High water level enhancement due to presence of flood walls	0	Not considered
ρD	Mean relative growth rate	0.001–0.08 years^−1
ҠT	Protection level decay rate	2 × 10^−5 year^−1	Di Baldassarre et al. (2015)
αD	Ratio between preparedness and awareness	0–15
ξT	Safety factor for flood walls	1.1	Da Deppo et al. (2004)
λ	Years in which the memory reduces to half its initial value	2–15 years

Table 2. Parameters of the socio-hydrological model, which vary depending on each ideal type of society.

	Society
Parameter	Risk Neglecting (fatalistic)	Risk Controlling (hierarchical)	Risk downplaying (individualist)	Risk monitoring (egalitarian)
αD	0	2.5-7.5	0.5-5.5	7.5-15
λ	2-8 yrs	5-10 yrs	2-5 yrs	5-15 yrs
levee construction	no	yes	no	no
ρD	0.02-0.08 yrs^−1	0.02-0.04 yrs^−1	0.02-0.04 yrs^−1	0.001-0.01 yrs^−1

Figure 2. Outcomes of the socio-hydrological model for each stylized society, (a) risk neglecting, (b) risk controlling, (c) risk downplaying and (d) risk monitoring, in terms of (1) levee construction, (2) social memory of flood event, (3) population density in the floodplain and (4) flood losses.

Figure 3. Sum of flood losses corresponding to the highest level of preparedness/awareness (i.e. highest α_D value) for each society.

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Di Baldassarre, G., et al., 2015. Debates—perspectives on socio-hydrology: capturing feedbacks between physical and social processes. Water Resources Research, 51, 4770–4781. doi:10.1002/2014WR016416

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Da Deppo, L., Datei, C., and Salandin, S., 2004. Sistemazione dei Corsi D’acqua [in Italian]. Padova, Italy: Libreria Int. Cortina Padova.

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