How are flood risk estimates affected by the choice of return-periods?

Ward, Philip J.; Moel, Hans de; Aerts, Jeroen C. J. H.

doi:10.5194/nhess-11-3181-2011

Cited by 141 publications

(111 citation statements)

References 50 publications

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“…The EAD is calculated by aggregating damage estimates of different probabilities by taking the integral under the exceedance probability-damage curve (risk curve) (Grossi et al, 2005;Meyer et al, 2009). Ward et al (2011b) have shown that flood damage related to five return periods (as available in this study: see Sect. 2.2) with a sufficient spread (low and high probabilities) are sufficient to estimate the EAD.…”

Section: Calculating the Expected Annual Damagementioning

confidence: 99%

Assessment of the effectiveness of flood adaptation strategies for HCMC

Lasage

Veldkamp

Moel

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, Asian cities in particular are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reduction measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea-level rise and socio-economic developments on flood risk for the flood-prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry-and wet proofing of buildings and elevating roads and buildings).A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage-damage curves for residential buildings. The model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in expected annual damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea-level scenarios and land-use scenarios. Together with information on costs of these strategies, we calculated the benefit-cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5 % and 5 %.The results of this modelling study indicate that the current flood risk in District 4 is USD 0.31 million per year, increasing up to USD 0.78 million per year in 2100. The net present value and benefit-cost ratios using a discount rate of 5 % range from USD −107 to −1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5 % leads to an increase in both net present value and benefit-cost ratio. The adaptation strategies wet-proofing and dry-proofing generate the best results using these economic indicators. The information on different strategies will be used by the government of Ho Chi Minh City to determine a new flood protection strategy. Future research should focus on gathering empirical data right after a flood on the occurring damage, as this appears to be the most uncertain factor in the risk assessment.

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Section: Calculating the Expected Annual Damagementioning

confidence: 99%

Assessment of the effectiveness of flood adaptation strategies for HCMC

Lasage

Veldkamp

Moel

et al. 2014

Nat. Hazards Earth Syst. Sci.

Self Cite

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“…Penning-Rowsell et al (2005) recommend a minimum of 5 return periods. Ward et al (2011) showed that the use of a small number of return periods is an important source of uncertainty. Nevertheless, only a set of five return periods (25 to 1250 years in present situation) could be considered in this basin-wide analysis that involved a transnational modeling chain (Table 2).…”

Section: Flood Frequencymentioning

confidence: 99%

Impacts of climate change on future flood damage on the river Meuse, with a distributed uncertainty analysis

et al. 2015

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Flood-risk assessments are an objective and quantitative basis for implementing harmonized flood mitigation policies at the basin scale. However, the generated results are subject to different sources of uncertainty arising from underlying assumptions, data availability and the random nature of the phenomenon. These sources of uncertainty are likely to bias conclusions because they are irregularly distributed in space. Therefore, this paper addresses the question of the influence of local features on the expected annual damage in different municipalities. Based on results generated in the frame of a transnational flood-risk-assessment project for the river Meuse (Western Europe) taking climate change into account, the paper presents an analysis of the relative contributions of different sources of uncertainty within one single administrative region (the Walloon region in Belgium, i.e. a river reach of approximately 150 km). The main sources of uncertainty are not only found to vary both from one municipality to the other and in time, but also to induce opposite effects on the computed damage. Nevertheless, practical conclusions for policy-makers can still be drawn.

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“…Several studies suggest that more return periods are needed to derive a reliable estimate of the risk (e.g. Messner et al, 2007;Ernst et al, 2010;Penning-Rowsell et al, 2010;Ward et al, 2011a).…”

Section: Limitationsmentioning

confidence: 99%

Contribution of land use changes to future flood damage along the river Meuse in the Walloon region

Beckers

Dewals²,

Erpicum³

et al. 2013

Nat. Hazards Earth Syst. Sci.

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Abstract. Managing flood risk in Europe is a critical issue because climate change is expected to increase flood hazard in many european countries. Beside climate change, land use evolution is also a key factor influencing future flood risk. The core contribution of this paper is a new methodology to model residential land use evolution. Based on two climate scenarios ("dry" and "wet"), the method is applied to study the evolution of flood damage by 2100 along the river Meuse. Nine urbanization scenarios were developed: three of them assume a "current trend" land use evolution, leading to a significant urban sprawl, while six others assume a dense urban development, characterized by a higher density and a higher diversity of urban functions in the urbanized areas. Using damage curves, the damage estimation was performed by combining inundation maps for the present and future 100 yr flood with present and future land use maps and specific prices. According to the dry scenario, the flood discharge is expected not to increase. In this case, land use changes increase flood damages by 1-40 %, to C 334-462 million in 2100. In the wet scenario, the relative increase in flood damage is 540-630 %, corresponding to total damages of C 2.1-2.4 billion. In this extreme scenario, the influence of climate on the overall damage is 3-8 times higher than the effect of land use change. However, for seven municipalities along the river Meuse, these two factors have a comparable influence. Consequently, in the "wet" scenario and at the level of the whole Meuse valley in the Walloon region, careful spatial planning would reduce the increase in flood damage by no more than 11-23 %; but, at the level of several municipalities, more sustainable spatial planning would reduce future flood damage to a much greater degree.

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How are flood risk estimates affected by the choice of return-periods?

Cited by 141 publications

References 50 publications

Assessment of the effectiveness of flood adaptation strategies for HCMC

Assessment of the effectiveness of flood adaptation strategies for HCMC

Impacts of climate change on future flood damage on the river Meuse, with a distributed uncertainty analysis

Contribution of land use changes to future flood damage along the river Meuse in the Walloon region

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