How reliable are projections of future flood damage?

P. Bubeck,L. M. Bouwer,J. C. J. H. Aerts,H. de Moel

doi:10.5194/nhess-11-3293-2011

Abstract

Abstract. Flood damage modelling is an important component in flood risk management, and several studies have investigated the possible range of flood damage in the coming decades. Generally, flood damage assessments are still characterized by considerable uncertainties in stage-damage functions and methodological differences in estimating exposed asset values. The high variance that is commonly associated with absolute flood damage assessments is the reason for the present study that investigates the reliability of estimates of relative changes in the development of potential flood damage. While studies that estimate (relative) changes in flood damage over time usually address uncertainties resulting from different projections (e.g. land-use characteristics), the influence of different flood damage modelling approaches on estimates of relative changes in the development of flood damage is largely unknown. In this paper, we evaluate the reliability of estimates of relative changes in flood damage along the river Rhine between 1990 and 2030 in terms of different flood-damage modelling approaches. The results show that relative estimates of flood damage developments differ by a factor of 1.4. These variations, which result from the application of different modelling approaches, are considerably smaller than differences between the approaches in terms of absolute damage estimates (by a factor of 3.5 to 3.8), or than differences resulting from land-use projections (by a factor of 3). The differences that exist when estimating relative changes principally depend on the differences in damage functions. In order to improve the reliability of relative estimates of changes in the development of potential flood damage, future research should focus on reducing the uncertainties related to damage functions.

Highlights

In recent years, flood management throughout Europe has gradually shifted from what are called “flood control approaches” to more integrated concepts, referred to as “flood risk management”
The analysis shows that the shift of the 32 328 hectares from agricultural to low-density residential areas results in a damage increase for these grid cells of 478 per cent in the Rhine Atlas Model (RAM) model, while it leads to an increase of 341 per cent according to the Damage Scanner model (DSM) model (Table 7)
The present study has investigated the reliability of estimates of relative changes in the development of potential flood damage with regard to the uncertainties stemming from flood damage modelling approaches

Summary

Introduction

Flood management throughout Europe has gradually shifted from what are called “flood control approaches” to more integrated concepts, referred to as “flood risk management”. While flood control approaches predominantly focused on preventing flood events with specific predefined return periods, flood risk management takes into account the expected consequences of flooding such as direct economic losses or loss of life (Buchele et al, 2006; de Moel et al, 2009; Merz et al, 2010). Risk in this context is defined as “probability times damage”, and describes the expected damage that can occur or will be exceeded with a certain probability in a certain period (e.g. Merz et al, 2010). A growing number of studies have estimated the range of possible changes in the development of future flood damage in Europe (Hall et al, 2005; Aerts et al, 2008; ABI, 2009; Feyen et al, 2009; Maaskant et al, 2009; Bouwer et al, 2010; te Linde et al, 2011)

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