Climate and hydrology - Mediterranean Mountain Environments - page 91

Crete are marked by some of the highest energy gradients, draining in only 20 km
from the highest peak (at nearly 2500 m) to the sea. Other mountainous islands
such as Corsica and the near coastal range of the Apennines follow similar trends,
draining from 2900 m altitude to the sea in only 70 km.
Although water resources and related issues are relatively well known and in-
vestigated in Mediterranean coastal zones, monitoring and modelling of snow-
precipitation inputs in the mountains and hinterlands as well as their cascading
effects still remain more or less a grey area. In the Mediterranean mountain re-
gions, the shortage of studies is even more serious due to the dispersed nature or
total lack of monitoring networks, the limited focus and attention given to snow and
glacier-related research, the remoteness and inaccessibility of some sites, the diffi-
culties in maintenance of a meteorological station at higher altitudes (Shaban et al.,
2005; Rimmer and Salingar, 2006) and the limited technological development of
meteorological and hydrological services in some countries. Often monitoring sta-
tions with long-term data are lacking, so that it is difficult to calculate long-term
trends or impacts of climate change (Figure 5.2). Some mountain ranges are devoid
of long-term measuring stations (e.g. the High Atlas, Pyrenees, Sierra Nevada). In
general there is a greater density of monitoring stations in the northern Mediter-
ranean, and long-term data (since the 1850s) are derived almost exclusively from
the western and northern Mediterranean; monitoring has been established in the
southern Mediterranean predominantly since the beginning of the twentieth cen-
tury, and in the eastern Mediterranean only from the 1940s (Xoplakie et al., 2004).
Remote-sensing techniques to estimate volumes of water originating from
snowmelt are common (Shaban et al., 2004; Chaponniere et al., 2005; Boudhari

50N

45N

40N

35N

30N a)

10W 5W 0 5E 10E 15E 20E 25E 30E 35E 40E

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950

Figure 5.2 Dates of beginning of precipitation records (in decades) across Mediterranean.
Reproduced from Xoplaki et al. (2004), with permission. ( A full colour version of this figure
appears in the colour plate section )