Environmental Engineering Reference
In-Depth Information
composition over the last thousands of years from deciduous and coniferous trees
to forest patches dominated by hard-leaved shrubland has modified the regional hy-
drology and climatology. Intensive utilization of forest by humans often overrides
the climatic effects. However, climate change may have a considerable impact on
changes in plant species composition - in the literature these are usually related to
temperature and CO 2 concentrations. Climate change may enhance the spread of
wildfires and result in species recomposition. It is necessary to advance the issue
of interactions between forest and changing hydrology under scenarios of climate
change as well as interactions between ecosystems, droughts and wildfires, taking
into account human interactions.
5.2.5
Dams and hydrology
Dam reservoirs have a major influence on river flow, particularly where water is ab-
stracted for irrigation (Figure 5.4). The Ebro in Spain, for example, has experienced
an estimated 63% discharge reduction, approximately half the reduction being at-
tributed to climate change and the other half to the impacts of the dam. Similarly,
the Moulouya River in Morocco has experienced a more than 70% decrease in dis-
charge since multiple dam construction.
It is estimated that discharge into the Mediterranean Sea has been reduced by
at least 50% over the past 100 years due to a combination of climate change and
anthropogenic use (Ludwig et al. , 2003). The influence of dams has been particu-
larly strong in modifying the discharge regimes in mountain environments. In or-
der to optimize the management of water resources with a snow component, it is
70
Spain
60
Turkey
50
Italy
40
Greece
Algeria
France
30
20
Morocco, Tunisia
Albania
10
0
1915
1925
1935
1945
1955
1965
1975
1985
1995
Figure 5.4 Evolution of the water retention behind dams in the drainage basin of the Mediter-
ranean Sea. Reproduced from Margat et Treyer (2004) and Ludwig et al. (2009), with permission
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