Global Change and Mountains: Consequences, Responses and Opportunities - Impact of Global Changes on Mountains: Responses and Adaptation - page 108

In Santiago and its surrounding areas 19500 ha of productive agricultural
land was lost due to urbanization between 1989 and 2003. Furthermore,
the transformation of 6789 ha of land with high vegetation productivity,
4224 ha of land with high soil moisture content, and 6654 ha with high
concentrations of biomass caused enormous loss to natural ecosystem of the
fragile mountains. The growth of imperviousness areas must be considered
one of the most devastating environmental impacts of urbanization in semi-
arid Mediterranean Andean landscapes. Urbanization is responsible for
increasing surface runoff, decreasing groundwater recharge, and polluted
water sources. It was also observed that the process of urbanization is
adversely affecting ecosystem services, such as groundwater recharge. This
situation is severely affecting the ecosystem in Mediterranean area where
average annual rainfall is less than 300 mm which falls in less than 20 days
annually, and the region faces severe drought that occurs at least once every
10 years (CONDESN 2011). The increasing urbanization is also contributing
towards warming through creating large urban heat islands. These heat
islands are affecting the cooler piedmont zones that have traditionally acted
as a source of airfl ow which cleans the heavily polluted city atmosphere
during the night (Romero 2004).
The expansion of urbanized centres is threatening the very last natural
relics in the European Alps. Many Alpine valleys have already lost most
of their biodiversity value due to urban sprawl. In the Alps, the initial
process of the evolution of settlement started in elevated areas of the most
accessible alpine valleys which offered the best conditions for housing and
agriculture. Later, with the growth and gradual spread of urban settlements
in the side valleys, the catchments of the easily reachable Rhone, Rhine, Inn,
and Adige Rivers have already lost most of their biodiversity prosperity.
Natural habitats and ecosystems in the valley bottoms—riverbeds,
fl oodplain forests, wetlands, and alpine steppes are now disappearing
with expanding urbanization. The development of transport infrastructure
associated with this urban growth is a major barrier for many species in
the Alps, preventing the establishment of ecological networks. Currently,
the Alps are experiencing a new level of urbanization with the average
living space occupied by a person has doubled since 1950. Although the
population is growing at a very slow rate, but there has been a sharp rise
in the number of residential properties. The continual expansion of cities,
towns, tourist and skiing resorts are now threatening even the more remote
and inaccessible areas in the Alps. Tourist complexes are signifi cantly
contributing to the rising level of urbanization in the sensitive mountains.
The urban expansion coupled with the growth of population has reduced
the permeability of land surfaces and, hence, the time of concentration of
fl oods, in the absence of mitigating solutions in the design of urban drainage
systems (urbanization and fl oods in Italian Alps). Similarly, the Rockies