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| Titel |
Hydropower and water supply: competing water uses under a future drier climate modeling scenarios for the Tagus River basin, Portugal |
| VerfasserIn |
Paulo Alexandre Diogo, João Pedro Nunes, António Carmona Rodrigues, Maria João Cruz, Nuno Grosso |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098465
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| Publikation (Nr.) |
 EGU/EGU2014-14147.pdf |
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| Zusammenfassung |
| Climate change in the Mediterranean region is expected to affect existing water resources,
both in quantity and quality, as decreased mean annual precipitation and more frequent
extreme precipitation events are likely to occur. Also, energy needs tend to increase, together
with growing awareness that fossil fuels emissions are determinately responsible for global
temperature rise, enhancing renewable energy use and reinforcing the importance of
hydropower. When considered together, these facts represent a relevant threat to multipurpose
reservoir operations.
Great Lisbon main water supply (for c.a. 3 million people), managed by EPAL, is located
in Castelo de Bode Reservoir, in the Tagus River affluent designated as Zêzere River. Castelo
de Bode is a multipurpose infrastructure as it is also part of the hydropower network system
of EDP, the main power company in Portugal. Facing the risk of potential climate change
impacts on water resources availability, and as part of a wider project promoted by EPAL
(designated as ADAPTACLIMA), climate change impacts on the Zêzere watershed where
evaluated based on climate change scenarios for the XXI century. A sequential
modeling approach was used and included downscaling climate data methodologies,
hydrological modeling, volume reservoir simulations and water quality modeling.
The hydrological model SWAT was used to predict the impacts of the A2 and B2
scenarios in 2010-2100, combined with changes in socio-economic drivers such
as land use and water demands. Reservoir storage simulations where performed
according to hydrological modeling results, water supply needs and dam operational
requirements, such as minimum and maximum operational pool levels and turbine
capacity. The Ce-Qual-W2 water quality model was used to assess water quality
impacts.
According to climate scenarios A2 and B2, rainfall decreases between 10 and 18% are
expected by 2100, leading to drier climatic conditions and increased frequency
and magnitude of drought periods, probably more acute by the year 2100 and in
scenario A2. As a result, a decrease in inflows to the Castelo de Bode reservoir
between 20 to 34% is expected, with emphasis in autumn. While for the near-term
scenarios this is mostly due to a decrease in median annual inflow; for the long-term
scenarios this is accompanied by lower inter-annual variability and a decrease of
magnitude of wet year inflows. Associated with increased precipitation erosion
potential, watershed sediment transport will probably tend to increase, enhancing
phosphorous transport into surface water and thus contributing to potential eutrophication
problems. However, modeling results do not indicate compromising water quality
degradation.
Decreased reservoir inflows should nevertheless be sufficient to sustain water supply,
considering an average annual consumption of 160hm3 y-1 and the legal prioritization of
water supply over hydropower production, as worst case average annual inflows scenarios are
estimated between 1000 and 1500hm3y-1. On the other hand, considering that
hydropower comprises downstream releases averaging 1400hm3y-1, restrictions to
energy production will probably be required to compensate lower inflow periods and
guaranty necessary water supply storage volumes. The presented modeling framework
provided an adequate tool for assessing climate change impacts on water resources,
demonstrating that climate scenarios are not likely to threaten Lisbon’s water supply
system but emphasizing the need for adequate reservoir management strategies
contemplating the risk of competitive water uses in the Castelo de Bode reservoir. |
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