Open AccessAssessing the probability of large‐scale flood loss events: a case study for the river R hine, G ermany
Author(s) -
Thieken A.H.,
Apel H.,
Merz B.
Publication year - 2015
Publication title -
journal of flood risk management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.049
H-Index - 36
ISSN - 1753-318X
DOI - 10.1111/jfr3.12091
Subject(s) - flood myth , environmental science , hydrology (agriculture) , homogeneous , streamflow , 100 year flood , drainage basin , scale (ratio) , population , return period , physical geography , geography , mathematics , cartography , geology , demography , geotechnical engineering , archaeology , combinatorics , sociology
Flood risk analyses are often estimated assuming the same flood intensity along the river reach under study, i.e. discharges are calculated for a number of return periods T , e.g. 10 or 100 years, at several streamflow gauges. T ‐year discharges are regionalised and then transferred into T ‐year water levels, inundated areas and impacts. This approach assumes that (1) flood scenarios are homogeneous throughout a river basin, and (2) the T ‐year damage corresponds to the T ‐year discharge. Using a reach at the river Rhine, this homogeneous approach is compared with an approach that is based on four flood types with different spatial discharge patterns. For each type, a regression model was created and used in a M onte‐ C arlo framework to derive heterogeneous scenarios. Per scenario, four cumulative impact indicators were calculated: (1) the total inundated area, (2) the exposed settlement and industrial areas, (3) the exposed population and 4) the potential building loss. Their frequency curves were used to establish a ranking of eight past flood events according to their severity. The investigation revealed that the two assumptions of the homogeneous approach do not hold. It tends to overestimate event probabilities in large areas. Therefore, the generation of heterogeneous scenarios should receive more attention.