Geography Reference
In-Depth Information
enormous scale of the problem, one that is not dissimilar in many countries of the
world (CESD
2012
). In brownfield sites within cities government funding is usu-
ally needed to provide the finance and even expertise to remove the old buildings,
polluted soil and other contaminants, since their removal is expensive. This usually
deters private developers who are attracted to cheaper sites on the city edge. But
once brownfield sites are cleaned with government help or control, the land is usu-
ally sold to developers to recoup the costs of the rehabilitation.
Another rehabilitation trend in cities with particularly active environmental poli-
cies has been to find
ways of reducing the excessive run-off and flooding
that of-
ten occurs after extreme rain events because water rapidly runs off the developed
surfaces, instead of soaking into the ground. The presence of large grassy or forest
areas in urban areas helps to mitigate this problem, but several new procedures have
also been adopted by cities. For example, the development of
storm ponds
is in-
creasingly mandatory in many urban areas. These are large hollows preserved from
development that can hold water from heavy rain events, reducing the rate of run-
off and the risk of floods in the storm water system. Such areas can also be used as
recreational space for most parts of the year since storms events are limited.
Water
gardens
are also being created in some residential areas, essentially areas at the cen-
tre of drainage ditches, which may have gardens at the surface but underneath con-
tain large sandy or gravel deposits that can hold large volumes of water. This means
that rain will drain more slowly into the sewer or river system. These provide an at-
tractive environmental feature in addition to reducing flooding.Finally, some cities
have adopted
de-sealing measures
on minor roads and parking areas, reducing the
amount of asphalt and concrete surfaces by replacing them with permeable bricks
and allowing grass to grow between the bricks as a new surface. This allows rain
water to percolate into the ground. The policy helps to replenish local groundwater
stocks which are usually diminished by urban development and, by allowing water
to soak into the ground, reduces the rate of runoff into storm sewers and the severity
of flash floods in urban areas that had previously effectively sealed their surfaces.
Although not entirely restricted to Europe, the continent has seen far more ex-
amples of attempts to
restore the natural streams or gullies and their environment
that were either covered over, or ignored by previous surrounding developments,
which meant they became derelict spaces in the city. Many waterways that were
essentially ignored by surrounding developments are being returned to something
like their natural state, using water filtration systems—natural ones like marshes or
artificial ones—to ensure the water is clean. The addition of walkways and green
areas alongside the watercourses ensures that many people are able to use and ap-
preciate these renewed natural environments. For example, Zurich is engaged in
the restoration of 40 km of these former waterways, using filtering techniques to
improve the water quality and also adding recreational facilities along their banks.
Old canals, abandoned for years, have also been getting the same treatment. This
has meant that in many countries once derelict canals have become valued addi-
tional recreational spaces, with new pathways along their route and with boats for
hire if the canal is sufficiently long and connected to other systems. Good examples
of the rehabilitation of old river-ways can be seen in Britain. One of the most com-
