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Titel |
Are large karstic springs good indicators for Climate Change effects on groundwater? |
VerfasserIn |
Elisabetta Preziosi, Emanuele Romano |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250080461
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Zusammenfassung |
Climate changes are expected to decrease the water availability in the Mediterranean area
especially during summer, due to the concurrence of a generalized negative trend in the
precipitation and an increased frequency of droughts. The use of groundwater can mitigate
droughts, because many aquifers have a large storage capacity and are potentially less
sensitive to climate change than surface water bodies, which often rely on groundwater
discharge to maintain their baseflow. However, the real effects of precipitation decline on
water availability must also account for human impacts, which conversely tend to increase,
partly as a result of climate change. Especially, the so called secondary impacts of climate
change, resulting from human intervention in water systems, are expected to have the largest
short-term effects on groundwater resources. Typical examples of secondary impacts on
groundwater are the increased abstractions particularly for irrigation. For these
reasons, groundwater heads are hardly directly usable as indicators of climate change
effects. On the other hand, large springs in mountain aquifers, which are very little or
not affected by well pumping, could be helpful to evaluate the primary impacts
of climate changes on groundwaters, although the paucity of long-term historical
data often limits an effective assessment of the direct consequences of climatic
forcing.
In this research we analyse three different unconfined karstic aquifers in Central Italy,
with average discharge ranging from 120 L/s to nearly 18 m3/s, which exhibit consistent
signals of the direct effects of climate changes on groundwater resources. The analysed
time series, although discontinuous, indicate declines of about 20% of the initial
discharge rate (10 years average) in the period 1938-2007. The detected trends are also
coherent with that of the regional standardized precipitation index and the Tiber
river discharge. Additionally, they show a fair correlation with the opposite of the
winter NAO Index, witnessing of a regional extent phenomenon and not just a local
behaviour.
On the grounds of these findings, we postulate that the primary effects of climate
change may be estimated also on heavily impacted groundwater bodies, comparing
them to the analysed springs. These signals are of paramount importance because
two of the analysed resources serve the large urban area of Rome with nearly 3
million inhabitants, and the possibility of occurrence of water scarcity conditions,
even for these huge groundwater systems, could be a challenge in the next decades. |
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