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| Titel |
Hydrologic climate change: are the existing dams still safe? The Flumendosa case study in Sardinia |
| VerfasserIn |
G. Maccioni, N. Montaldo, A. Saba |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250030361
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| Zusammenfassung |
| The problem of the hydraulic safety of existing dams is becoming crucial due to the
recent increase of floods. In Sardinia dams were built for both electric production
and water supply for irrigation and civil uses during the 1920-1960 period. Recent
floods showed a significant increase in magnitude and frequency, supporting the
hypothesis of a hydrologic climate change. Are the existing dams still safe? For
answering the question 1) a method for estimating the flood hydrograph with return
period of 2000 years also accounting for possible climate change is developed, 2) an
hydrologic model is implemented, and 3) the hydraulic safety of existing dams is tested.
The case study is the Flumendosa river basin (area of about 1300 km2) located in
central-eastern Sardinia (Italy), whose reservoir system (3 dams) is the main water
supply of southern Sardinia, including its largest city, Cagliari. The smallest dam is
located in the upper part of the basin with a drainage area of about 50 km2. At this
dam, during the December 2004 flood an extremely high peak discharge of around
2000 m3/s was observed (total daily rain was of 600 mm). In the basin the soils
are generally of modest thickness, the vegetation throughout the basin has been
in part altered by human activities, with many areas (before covered by scrubs)
converted to pasture. Urbanized areas are a minor component. Rainfall and discharge
data of historical floods (from 1940) were acquired so that a fully evaluation of the
hydrologic model has been performed. The distributed hydrologic model is an event
model (FEST) which assesses runoff through a simplified approach based on Soil
Conservation Service equations and runoff propagation through the Muskingum-Cunge
approach. The FEST model well simulates historical and recent floods. The results
demonstrated that the dams are not safe for the estimated flood with return period of
2000 year, but also demonstrated the extreme uncertainty in the estimate of floods
with extremely high return period. The proposed method is able to include this
uncertainty. |
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