Environmental Engineering Reference
In-Depth Information
will each have populations of more than 20 million. Moreover, it is estimated
that between 2010 and 2015 some 200,000 people on average will be added to
the world's urban population every day with 91% of this increase expected
to take place in developing countries [6]. For many emerging cities, soaring
populations are extremely difficult to manage; at current rates of growth,
the number of inhabitants in Nigeria's Lagos will double by 2020, mainly
through expansion of informal settlements. By contrast, most mature cities
(as well as many transitional ones) will need to address a different kind of
demographic challenge in the form of population ageing.
There is a continuous debate about megacities. On one level, these super-
sized cities are seen as the engines of the global economy, efficiently con-
necting the flow of goods, people, culture and knowledge. They offer, at least
potentially, unprecedented concentrations of skills and technical resources
that can bring increased wealth and improved quality of life to vast numbers
of people. However, megacities also conjure up an altogether darker vision.
Most cities in the developing world face huge challenges ranging from con-
gestion and pollution to security threats and inadequate services groaning
under the weight of excessive demand. Those in the developing world also
struggle to cope with the rapid growth of informal settlements. In 2006,
almost one in three members of the world's urban population lives in slums,
without access to good housing or basic services [7].
Today's megacities are not only bigger than the cities of the mid-20th century
but also more complex. For one, they are increasingly competing with, and
dependent on, relationships with other cities in the global economy. At the
same time, we are witnessing the emergence of new city regions—sprawling
conurbations that extend far beyond the boundaries of a single city. Examples
include the 'BosWash stretch' (extending from Boston, MA, to Washington, DC)
in the United States, and Chongqing in China. These huge megacity regions
create a new urban dynamic. Commuters travel large distances from densely
populated suburbs. Economic activity frequently becomes de-concentrated,
dissipating from the centre to the periphery. Often fragmented systems of met-
ropolitan governance have not caught up with this trend, with the result that it
is difficult to deliver an efficient, holistic approach to infrastructure challenges
at a metro regional level [8]. In addition, other new spatial configurations are
increasingly taking place, such as urban corridors and city regions. These large
urban configurations, as grouped in networks of cities, amplify the benefits of
economies of agglomeration, increasing efficiencies and enhancing connectiv-
ity. They also generate economies of scale that are beneficial in terms of labour
markets, as well as transport and communication infrastructure, which in turn
increase local consumer demand [6].
2.2.2 Role and Competitiveness
In the context of continuous globalisation, there is a focus on competitive-
ness to attract investments to increase cities' prosperity. In this quest, there is
