SuDS in London - a guide

2.1 What is unique
about London?
This chapter explains some of the
conditions particular to London, although
some may also be found in other
metropolitan areas. Some are unique,
others less so, but all will influence the
integration of SuDS into the public realm.
London is by far the UK’s biggest
metropolitan region, occupying an
area four times that of Birmingham,
and is experiencing a period of rapid
intensification of use and development.
The Capital sits within the Thames
River Basin and contributes the largest
share to the 17% of the Basin’s area which
is urbanised.
Hand in hand with urbanisation has come
population growth. London’s population
exceeded its pre-war peak of 8.6 million
in 2015 and is forecast to grow by 100,000
per year to 2030. Much of this growth
is expected to be accommodated in the
existing built-up area, putting increasing
pressure on the available water supply and
drainage infrastructure in the Capital.
As London develops and grows, its public
realm needs to work much harder. Not
only will it be more intensively used, it
will also need to fulfil multiple demands,
including drainage.
Responsibility for London’s public realm is
divided between TfL and 33 local planning
authorities, plus other private landowners.
Like most UK cities, much of London’s
drainage infrastructure consists of piped
networks. Climate change, population
increase and densification all contribute
to surface water runoff and increase the
pressure on the network. If our drainage
network is not to exceed capacity or need
total replacement at significant cost and
disruption, a long-term approach to surface
water runoff management is needed.
The Thames Tideway Tunnel is addressing
some of these issues at a strategic level,
particularly in relation to events of intense
rainfall. Nevertheless, many local SuDS
interventions are needed to manage the
process effectively.
The opportunities for SuDS, both above
and below ground, will vary across
London. For instance, in conservation
areas designated for their landscape,
architectural and historic interest, there
may be more limitations than in an area of
redevelopment, where a comprehensive
approach to water resource management
may be designed and implemented.
For the former, and significant areas of
central London, this might involve the
need to retrofit SuDS into the streetscape
which is addressed in more detail later in
this chapter.
Other factors also highlighted in this
chapter, include archaeology and geology.
These can both define the scope and
appropriateness of the scheme and where,
with the former, there is over 2,000 years
of history in the heart of the city.
Well-designed and maintained SuDS can
make a major contribution to public realm.
They can help reduce flood risk, improve
water quality, and create a sense of place.
This guidance shows how this can be done.
17 2 The London context