Influence of flood frequency on residential building losses

Abstract

Abstract. For the purpose of flood risk analysis, reliable loss models are an indispensable need. The most common models use stage-damage functions relating damage to water depth. They are often derived from empirical flood loss data (i.e. loss data collected after a flood event). However, object specific loss data (e.g. losses of single residential buildings) from recent flood events in Germany showed higher average losses in less probable events, regardless of actual water level. Hence, models that were derived from such data tend to overestimate losses caused by more probable events. Therefore, it is the aim of the study to analyse the relation between flood damage and recurrence interval and to propose a method for considering recurrence interval in flood loss modelling. The survey was based on residential building loss data (n = 2158) of recent flood events in 2002, 2005 and 2006 in Germany and on-site recurrence interval of the respective events. We discovered a highly significant positive correlation between loss extent and recurrence interval for classified water levels as well as increasing average losses for longer recurrence intervals within each class. The application of principal component analysis revealed the interrelation between factors that influence the damage extent directly or indirectly, and recurrence interval. No single factor or component could be identified that explained the influence of recurrence interval, which led to the conclusion that recurrence interval cannot substitute, but complement other damage influencing factors in flood loss modelling approaches. Finally, a method was developed to include recurrence interval in typical flood loss models and make them applicable to a wider range of flood events. Validation including statistical error analysis showed that the modified models improve loss estimates in comparison to traditional approaches. The proposed multi-parameter model FLEMOps+r performs particularly well.

Adaptability and transferability of flood loss functions in residential areas

“…For this, the absolute financial damage to buildings was indexed to the reference year 2006. In addition, the indexed total value of buildings (replacement costs) was calculated as described in detail by Thieken et al (2005) and Elmer et al (2010). As not all interviews contained sufficient information for the calculation of the loss ratio for residential buildings these relative losses were only available for 1121 cases.…”

“…Since then, flood damage assessment methods were developed in many countries with different complexity and purposes like the "manual of assessment techniques" published by Penning-Rowsell and Chatterton (1977) as the first application in Europe. Currently, most damage models still use inundation depth as the main impact parameter (see e.g., Merz et al, 2010;Jongman et al, 2012 for an overview), but some models also integrate additional parameters like flow velocity (e.g., Schwarz and Maiwald, 2007;Pistrika and Jonkman, 2010), contamination (e.g., Kreibich and Thieken, 2008;Prettenthaler et al, 2010), the duration of flooding (e.g., Dutta et al, 2003;Penning-Rowsell et al, 2005) or the recurrence interval (e.g., Elmer et al, 2010). With regard to the consideration of different resistance parameters, the majority of damage models differentiates between the use or type of building (e.g., Oliveri and Santoro, 2000;Dutta et al, 2003;Kang et al, 2005;Büchele et al, 2006;Schwarz and Maiwald, 2007;Kreibich and Thieken, 2008;Thieken et al, 2008).…”

Preface: Flood-risk analysis and integrated management

“…Fuchs et al, 2015) and the vulnerability of the exposed elements in case a flood occurs, such as residential buildings (e.g. Elmer et al, 2010). Moreover, there is an increasing demand for risk assessments that evaluate insights into hazards, consequences and vulnerabilities in an integrated way Thieken et al, 2014;Merz et al, 2014).…”

Assessment of flood loss model transferability considering changes in precaution of flood-affected residents in Germany

“…in [8,[10][11][12][13][14][15][16]. In this context, studies of [16][17][18][19] confirm that multifactorial models can estimate flood losses more reliably than traditional depth-damage functions.…”

“…[16,17,19] Before the results of the second approach will be described in more detail, it had to be clarified whether the split sampled model FLEMO2013split was even able to calculate losses of the 2013 flood and hence if the subsequent applied FLEMO2013 model was generally reliable. The results of the model performance are also summarized in Table 6 (centre).…”