 |
| Titel |
Maximising the usefulness of flood risk assessment for the River Vistula in Warsaw |
| VerfasserIn |
A. Kiczko, R. J. Romanowicz, M. Osuch, E. Karamuz |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1561-8633
|
| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 12 ; Nr. 13, no. 12 (2013-12-23), S.3443-3455 |
| Datensatznummer |
250085597
|
| Publikation (Nr.) |
 copernicus.org/nhess-13-3443-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| The derivation of the flood risk maps requires an estimation of maximum
inundation extent for a flood with a given return period, e.g. 100 or
500 yr. The results of numerical simulations of flood wave propagation
are used to overcome the lack of relevant observations. In practice,
deterministic 1-D models are used for that purpose. The solution of a 1-D model
depends on the initial and boundary conditions and estimates of model parameters
based on the available noisy observations. Therefore, there is a large
uncertainty involved in the derivation of flood risk maps using a single
realisation of a flow model. Bayesian conditioning based on multiple model
simulations can be used to quantify this uncertainty; however, it is too
computer-time demanding to be applied in flood risk assessment in practice,
without further flow routing model simplifications. We propose robust and
feasible methodology for estimating flood risk. In order to decrease the
computation times the assumption of a gradually varied flow and the application
of a steady state flow routing model is introduced. The aim of this work is an
analysis of the influence of those simplifying assumptions and uncertainty of
observations and modelling errors on flood inundation mapping and a quantitative
comparison with deterministic flood extent maps. Apart from the uncertainty
related to the model structure and its parameters, the uncertainty of the
estimated flood wave with a specified probability of return period (so-called
1-in-10 yr, or 1-in-100 yr flood) is also taken into account. In
order to derive the uncertainty of inundation extent conditioned on the design
flood, the probabilities related to the design wave and flow model uncertainties
are integrated. In the present paper that integration is done whilst taking into
account the dependence of roughness coefficients on discharge. The roughness is
parameterised based on maximum annual discharges. This approach allows for the
relationship between flood extent and flow values to be derived, thus giving
a cumulative assessment of flood risk. The methods are illustrated using the
Warsaw reach of the River Vistula as a case study. The results indicate that
deterministic and stochastic flood inundation maps cannot be quantitatively
compared. We show that the proposed simplified approach to flood risk assessment
can be applied even when breaching of the embankment occurs, with the condition
that the flooded area is small enough to be filled rapidly. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|