Environmental Engineering Reference
In-Depth Information
Climate and hydrology
Carmen de Jong, Ibrahim G urer, Alon Rimmer, Amin Shaban
and Mark Williams
5.1
Introduction
State-of-the-art reviews on the dynamics of climate and hydrology in Mediterranean
mountain regions show that this is a subject that receives little attention compared to
mountain studies in other, more popular mountain ranges such as the Alps, Rockies
and Himalayas (Messerli and Ives, 1997; Bohm
et al.,
2001; Viviroli
et al.,
2003;
Corripio and de Jong, 2005; de Jong
et al.,
2005a,b,c; Bales
et al.,
2006). However,
in the context of the significance and contributing potential of the world's mountains
as water towers to the forelands, Mediterranean mountains are classified as having
a high contributing potential to dry lowlands (Viviroli
et al.,
2007). Climatological
and hydrological literature on the mountainous catchments of the Mediterranean
Basin itself is much sparser than that of other regions of the world with a Mediter-
ranean climate, such as California.
The Mediterranean Basin has unique geographical and climatological charac-
teristics, since its periphery is almost entirely surrounded by mountains at a short
distance from the sea (Figure 5.1). Therefore the dominant climate and hydrology
around the Mediterranean, although essentially determined by latitude, is strongly
influenced by the mountainous relief (Rhanem, 2008). Topographical gradients
from sea level up to 2000-4000 m altitude are not uncommon. Mediterranean moun-
tains zones, whether consisting of chains or individual peaks, act locally as cold
islands with strong climatic gradients (Ozenda, 1975). Typical for such extremes
is, for example, the High Atlas in Morocco, which can experience temperatures of
−
18
◦
C yet is surrounded by the Sahara within less than 200 km distance.
Mediterranean climatology is complex, and basically unites three different zones:
the sub-Saharan climate, the dry continental climate to the east and the more conti-
nental climate to the north. It forms the boundary between the mid-altitude and trop-
ical climate, between vegetated and non-vegetated, and between highly and poorly
developed regions. The climate, together with the distribution and altitudinal range
of mountain ranges (Table 5.1), strongly influences water availability and ensuing
