Environmental Engineering Reference
In-Depth Information
strong influence on the spatio-temporal dynamics of both soil moisture (Menziani
et al.,
2005) and the groundwater table. Whilst literature on precipitation/run-off
and evapotranspiration in the Mediterranean lowlands is abundant, studies on snow
and glacier hydrology in Mediterranean mountains are generally lacking and work
is mostly confined to the Pyrenees (Lopez-Moreno and Garcia-Ruiz, 2004).
Mountains in general comprise one of the most sensitive environments of our
globe and are therefore excellent indicators of but also victims of climate change.
This concerns not only the Mediterranean mainland and island mountains but
equally the Alps. Mountains act as amplifiers for different climatological phenom-
ena related to altitude, such as radiation, temperature, precipitation and relative hu-
midity. Special valley effects in winter, such as inversions, account for additional
perturbations in the system. The spatial variability of these parameters is also am-
plified in mountains, bringing more extreme conditions such as flooding (Bacchi
and Villi, 2005) or water scarcity (de Jong, 2009).
As for other mountain chains worldwide, Mediterranean mountains are gener-
ally considered as the 'water towers' for the surrounding lowlands (Viviroli
et al.,
2003). In the semi-arid areas of the Mediterranean, run-off can contribute from 5%
to 90% of total water supply (Viviroli
et al.,
2007). Similarly, these mountains are
classed among the world's most important biodiversity hotspots and are therefore
particularly sensitive to climate and human change. The Mediterranean is of spe-
cial importance since it is a region with its own endemic species (citrus fruit, olive
trees, almond trees,
Pinus pinea
etc) whose agricultural exploitation has long been
influenced by the prevailing climate.
The main challenges of the Mediterranean mountain climate and hydrology are
its extremes, both in terms of droughts and floods, man-made modifications to the
water cycle, in particular dams, and their amplification by climate change. The cli-
matic regime together with the influence of dams and other man-made structures
on the main rivers, cause strong variations in freshwater input into the Mediter-
ranean Basin (Ludwig
et al.,
2009). Human water consumption is greatest along
the Mediterranean coasts, where population pressure is strongest, due to perma-
nent and tourist populations and to intensive irrigation. The upstream-downstream
relations for water availability and consumption are particularly important.
The analysis of past climates, for example from lake sediments, is very impor-
tant for future climate projections (Tonkov
et al.,
2002; Ghosn
et al.,
2010). The
Mediterranean region has always been a very sensitive environment, and indicators
for climate change trace back as far as the Bible and the Pharaonic Period (droughts,
floods, pests, famines). During the Holocene, there have been clear triggers and re-
sponses to changes in climate and hydrology, reflected by the spread in farming,
and maritime and terrestrial trade around the Mediterranean and Africa. Histori-
cally, coastal zones have dominated and the importance of their mountains in the
hinterland has often been neglected.
The Mediterranean is particularly sensitive to climate change (Jeftic
et al.,
1992).
Climate change and increasing population pressure have caused water stress in
many mountain regions that depend on rainfall and meltwater from snow and
