18
H.-J. Bolle
hectare using the water from nearly 25 smaller dams which have been constructed
since 1950 (Wagner, 2000). This is also the practise in Tunisia and Algeria but in
a smaller extent. The irrigation of 1.6 million hectare is the aim of the large Atatiirk
dam in Turkey. In Lybia a 600 - 800 km long water tube of 4 m diameter is
constructed to irrigate 200 000 - 400 000 ha with prehistoric water from underneath
the Sahara. It is expected that this not renewable water reservoir will spend the
necessary water for 400 years. The use of smaller water reservoirs down to private
pond sizes is becoming very popular to bridge the dry summer months with winter
rain water. In Spain a system of dams and channels was build to provide for
balanced supply. Over long distances water is transported from the central parts of
the Iberian Peninsula through the Canal de Trasvase Tajo Segura to the South. The
new Spanish water plan even attempts to branch off Ebro water to Murcia and
Almeria in the South. The area around Almeria, were water is very scarce, is a
major provider of vegetables already in very early spring. For this purpose the whole
peninsula of Llanos de Almeria as well as other places are covered by greenhouses
made of plastic covers. Not very far away and adjacent to the desert of Almeria near
Jaen a monoculture of olive trees under which all undergrowth is removed stretches
over a terrain of about 10 3 - 10 4 km 2 • Olive trees already in ancient times served as
a stabilizer of threatened landscapes.
The ground water level in several parts of central and south-eastern Spain
declines up to one metre per year. This being also the case in many other regions of
the Mediterranean area. In the Messara valley of Crete, as another example, the
groundwater level fell about 25 m from 1985 to 1996 (Grapes, 2000). In total 22 000
ha are estimated to be under irrigation by 1997 in the Mediterranean basin (Wagner
2001) which is an increase of 39 % since 1975. One of the consequence of these
irrigation systems is that albedo, evaporation and surface temperature are regionally
changed. An additional factor to agriculture is the construction of tourist facilities
with pools near the coast but also in the hinterland which draws on the water
resources.
In Greece, e.g. east of Athens, new villages which will draw on water resources
are build into a treeless landscape completely degraded by wild fires and overgrazing
(Schultze-Westrum, 1994, Papanastasis, 2000). Whether man-made or caused by
natural events like lightening, forests and macchia in the Mediterranean are
repetitively damaged by wild fires which either lead to degraded land or to the
regrowth of unpretentious vegetation, mostly macchia, or of species the seeds of
which better survive the fire. Thus it has been observed in Tuscany that a forest of
Pinus pinea once planted by man regrew after burned down as Pinus halipensis
forest. Reforestation efforts are large, especially in Spain, but this is a slow process,
sometimes interrupted by new fires.
The pattern of human actions on land throughout the Mediterranean basin is
very differentiated and regionally controversial. Some areas became dryer during the
last century, some areas received more water due to human actions, sometimes on
the expense of other areas or of non-renewable reservoirs. It is difficult to judge to
which climatic effects the sum of all these activities finally will result. The extent
of the various regional impacts have not yet been established. It may well be that the
H.-J. Bolle
hectare using the water from nearly 25 smaller dams which have been constructed
since 1950 (Wagner, 2000). This is also the practise in Tunisia and Algeria but in
a smaller extent. The irrigation of 1.6 million hectare is the aim of the large Atatiirk
dam in Turkey. In Lybia a 600 - 800 km long water tube of 4 m diameter is
constructed to irrigate 200 000 - 400 000 ha with prehistoric water from underneath
the Sahara. It is expected that this not renewable water reservoir will spend the
necessary water for 400 years. The use of smaller water reservoirs down to private
pond sizes is becoming very popular to bridge the dry summer months with winter
rain water. In Spain a system of dams and channels was build to provide for
balanced supply. Over long distances water is transported from the central parts of
the Iberian Peninsula through the Canal de Trasvase Tajo Segura to the South. The
new Spanish water plan even attempts to branch off Ebro water to Murcia and
Almeria in the South. The area around Almeria, were water is very scarce, is a
major provider of vegetables already in very early spring. For this purpose the whole
peninsula of Llanos de Almeria as well as other places are covered by greenhouses
made of plastic covers. Not very far away and adjacent to the desert of Almeria near
Jaen a monoculture of olive trees under which all undergrowth is removed stretches
over a terrain of about 10 3 - 10 4 km 2 • Olive trees already in ancient times served as
a stabilizer of threatened landscapes.
The ground water level in several parts of central and south-eastern Spain
declines up to one metre per year. This being also the case in many other regions of
the Mediterranean area. In the Messara valley of Crete, as another example, the
groundwater level fell about 25 m from 1985 to 1996 (Grapes, 2000). In total 22 000
ha are estimated to be under irrigation by 1997 in the Mediterranean basin (Wagner
2001) which is an increase of 39 % since 1975. One of the consequence of these
irrigation systems is that albedo, evaporation and surface temperature are regionally
changed. An additional factor to agriculture is the construction of tourist facilities
with pools near the coast but also in the hinterland which draws on the water
resources.
In Greece, e.g. east of Athens, new villages which will draw on water resources
are build into a treeless landscape completely degraded by wild fires and overgrazing
(Schultze-Westrum, 1994, Papanastasis, 2000). Whether man-made or caused by
natural events like lightening, forests and macchia in the Mediterranean are
repetitively damaged by wild fires which either lead to degraded land or to the
regrowth of unpretentious vegetation, mostly macchia, or of species the seeds of
which better survive the fire. Thus it has been observed in Tuscany that a forest of
Pinus pinea once planted by man regrew after burned down as Pinus halipensis
forest. Reforestation efforts are large, especially in Spain, but this is a slow process,
sometimes interrupted by new fires.
The pattern of human actions on land throughout the Mediterranean basin is
very differentiated and regionally controversial. Some areas became dryer during the
last century, some areas received more water due to human actions, sometimes on
the expense of other areas or of non-renewable reservoirs. It is difficult to judge to
which climatic effects the sum of all these activities finally will result. The extent
of the various regional impacts have not yet been established. It may well be that the