Application of a model to the evaluation of flood damage

Abstract

This paper presents the initial results of a common methodology for the evaluation of damage produced by a flood. A model has been developed for flood damage estimation based on a geographic information system (GIS). It could be used by land administration bodies and insurance companies to manage flood-related damage data. The model simulates flood scenarios and evaluates expected economic losses from the impact of floodwaters on exposed elements, through the application of a computational model elaborated by GIS. During the development of the model, the Boesio Stream, a small watercourse flowing into Lake Maggiore (Lombardy, northern Italy) which was recently affected by a flash flood, was used as case study to test and calibrate the methodology. The method could be used either as a forecasting tool to define event scenarios, utilizing data from events simulated with a hydraulic model, or for real-time damage assessment after a disaster. The approach is suitable to large-area damage assessment and could be appropriate for land use planning, civil protection and risk mitigation.

Adaptability and transferability of flood loss functions in residential areas

“…The derivation of new stage-damage functions and the adaptation of the multi-factorial loss model shows that loss data where these models are based on and which are collected in a neighboring and also mountainous region with assumable similar building and flood event characteristics and further loss figures yields remarkably better results than (more) loss data from spatially different regions and dissimilar flood events with, for example, higher process intensities. This is in line with prior statements (e.g., Oliveri and Santoro, 2000;Kang et al, 2005;Luino et al, 2009) that loss functions should only be applied in related regions with similar depth-damage relationships particularly when water depth is the only factor considered. But even when other loss decisive parameters like contamination are additionally taken into account, no reliable loss estimates could be produced when the underlying loss data originate from various geographical regions like the German-wide data set.…”

“…This may be explained by the larger heterogeneity of the German-wide data set, collected in different geographical regions and from various flood events with different impacts and process characteristics. As pointed out by specific building characteristics, for instance, may affect the specific relationships between losses to buildings and flood impact factors leading to a large variation of damage data in more heterogeneous regions (Luino et al, 2009;Merz et al, 2010). This assumption is also supported by our results.…”

“…Until now, there is no standard procedure to determine the flood impact (Oliveri and Santoro, 2000;Nicholas et al, 2001;Luino et al, 2009) resulting in a wide range of flood damage models with substantial differences in their underlying approaches Papathoma-Köhle et al, 2011;Jongman et al, 2012;Meyer et al, 2013).…”

“…Although it is known that different processes and characteristics of a flood event govern flood damage (e.g., Kelman and Spence, 2004;Schwarz et al, 2005;Thieken et al, 2005;Merz et al, 2010), the majority of damage estimations apply simple depth-damage functions (Luino et al, 2009;Merz et al, 2010;Meyer et al, 2013) as it is internationally accepted as standard approach for assessing direct urban damage (Smith, 1994). According to Papathoma-Köhle et al (2011) the usage of stage-damage functions can be dated back to the seminal paper of White (1945), who linked the water level to relative (i.e., the loss ratio) or total (i.e., in monetary values) damage.…”

“…In more general terms, the overall applicability and transferability of flood models to other geographical regions is scarcely investigated and thus still compose a major gap in current flood damage modeling research Merz et al, 2010;Jongman et al, 2012;Meyer et al, 2013). What most damage models have in common is that they have been derived for a certain study area with specific regional building characteristics and further specific relationships between losses to buildings and flood impact factors; reliable model application is assumed to be restricted to its region of origin (Oliveri and Santoro, 2000;Kang et al, 2005;Luino et al, 2009;Merz et al, 2010;Papathoma-Köhle et al, 2011). Thus, these models cannot be easily transferred to other regions without any model adaptation and validation Papathoma-Köhle et al, 2011;Meyer et al, 2013) as building types, their asset values and their quality differ in other parts of the world.…”