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| Titel |
Dyke failure scenarios in Ubaye River, France using hydraulic modeling |
| VerfasserIn |
Azadeh Ramesh, Thomas Glade, Gabriel Parodi, Dinand Alkema |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055049
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| Zusammenfassung |
| In case of dyke failure, it is essential to evaluate possible effects in advance. In this context,
simulations of different failure scenarios applying various hydrograph propagations are
useful to investigate the river behaviour during a flood event. This study has been
carried out for the Ubaye River, Southeast of France which has a modified and
natural river bed. These two parts include a canalized channel in the city and the
undisturbed river bed without any infrastructures. The dykes are located in urban
reach of the river having an approximate height of 2 m and a length of 3.5 to 4 km.
The applied analysis include the scenarios (1) and (2): Modeling of the 2008 flood
having a maximum discharge of 209 m3/s with and without the dykes, respectively
and scenario (3): Modeling of flood event of 1957 with maximum discharge of
490 m3/s considering of the dyke. HEC-RAS (US Department of Defense, Army
Crops of Engineers) was used to model the dyke breach. Input of the geometry was
achieved with HEC-GeoRAS (ArcGIS extension) and additionally, ArcGIS 9.3.1 was
applied for spatial processing of the input and model of data, and to visualize the
outputs.
In case of scenario (1) a normal retention depth of water and velocity were shown
in the channel. The model indicated that maximum water depth and velocity in
Ubaye River were approximately 2 m and 2.90 m/s respectively. This corresponds
to the field reports of the flood 2008. The scenario (2) is affected by the channel
maintenance and dyke structural integrity. The results showed that the banks were
overtopped by the flood. In scenario (3) the effects were much more disastrous
than in case of scenarios (1) and (2), with the dykes being overtopped on several
sections in both banks in the urban sectional area and the natural reach of the river,
assuming the same river morphology which was applied for scenarios (1) and (2). In
scenario (3) it has been evaluated that if a severe flood happens both the structure of
the dyke and its height are not sufficient to protect the area from inundation. So
definitely overtopping of the dyke with current morphology of the river and current
dyke structure could not protect the area in case of such design flood events. It is
strongly recommended that the flat areas in both the city and natural sectors should be
protected with dykes. Additionally, the channel modifications/improvements are
foreseen.
Keywords: Dyke breaks scenario, hydraulic simulation, flooded area, channel
maintenance. |
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