book "Building the Water Sensitive City" - Royal Haskoning

Urbanisation
For the first time in the history of the planet more people live in cities than anywhere else. The
21st century really is “the century of the city”. This same phenomenon of rapid urbanisation is
also apparent in the Netherlands, particularly in the Randstad conurbation. Today, we live in one
of the most densely populated countries in the world.
Urbanisation often has detrimental effects for water management in an area. Precipitation can
no longer infiltrate the ground and water runs off faster into canals, rivers and streams that
range over the area. As a result, they have to drain away greater volumes of water, increasing the
risk of flooding, or even dike breaches in the lower reaches of rivers.
Urbanisation of the Randstad (Atlas van de Nederlandse Waterstad, 2005)
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Urbanisation in the world (National Geographic, 2009)