FEATURE
SECTION
Resilience
Protecting properties
against floods
Surface water flooding is increasingly affecting millions of homes in the
UK and Europe. Property level protection has been advocated and a
six-step process developed. Could this be an option for New Zealand?
BY IAIN WHITE, PROFESSOR OF ENVIRONMENTAL PLANNING, UNIVERSITY OF WAIKATO
Potential for property level protection
Due to this shift, the potential for utilising
property level protection (PLP) is now advocated in the UK. Although the term refers to
individual properties, it also encompasses
the use of technology that can protect on a
community scale.
PLP can keep water out of buildings or
local areas. If ingress does occur, it can
limit damage and speed the recovery of
Figure 1: Wet testing of door and window guards.
people and places. For instance, the use of
material that is resistant to water damage
OVER THE PAST few d e c ad e s , f l o o d
From being unrecognised a decade ago,
enables people to move back into their home
events in Europe have changed, and as a
surface water flooding from inadequate
much more quickly and reduces the costs of
consequence, the way that excess water is
drainage is now the major source of flood
refurbishment.
managed has changed too.
risk in the UK. This is a growing trend in
Innovative solutions
many European countries as rainfall events
Innovative technologies may encompass
Problem of surface water flooding
become more intensive, consistent with
aspects such as door guards (see Figure 1),
Taking England as an example, there
climate change predictions, coupled with a
demountable barriers or air bricks that are
are around 23 million homes. Of these,
gradual intensification of urban areas.
able to resist the entry of water to homes
6.9 million are now identified as being at
Floods are no longer something to hold
risk from flooding, up four-fold over the last
back behind walls next to rivers. They need
10 years, and it is the nature of the increase
to be managed differently, and resilience
that has proved most challenging.
needs to be built into towns and cities.
50 — June/July 2015 — Build 148
to a depth of around 600 mm and in some
cases significantly higher.
On a community scale, perimeter barriers
may also be deployed in either a temporary
Resilience
FEATURE
SECTION
Step 1 provides guidance on knowing the
risk, giving links to official maps to enable
the specific flooding threat. If this suggests
PHOTOGRAPH – THE ENVIRONMENT AGENCY
that there is a risk, stage 2 helps users to
Figure 2: Demountables in action at Bewdley, Worcestershire, UK.
or automated fashion to protect areas. Figure
●●
2 shows a demountable scheme in Bewdley,
consider and plan a scheme, find out about
the range of products available and think
about individual requirements.
If a decision is taken to proceed, the
following stages extend this logical process
and cover information on survey, design and
installation, right down to the final aspect of
operation and maintenance.
At all stages, the guidance is simple and
how to ensure that the technology will be
impartial and provides links to further
installed and maintained correctly.
sources of information and references if
Worcestershire, UK, that can hold back
required.
floodwaters up to 3 m in height.
No best-practice guidelines
Property level protection uses
It became clear that there are no best-practice
been endorsed by many organisations. It has
PLP is particularly useful where:
guidelines for selection, installation and
also influenced wider policy and practice by,
maintenance of PLP anywhere in Europe.
for example, informing the update of PLP
●●
there is uncertainty regarding the degree
of risk
●●
●●
●●
Although people could see its potential,
Since its development, the guidance has
standards (PAS 1188) issued by the British
buildings are of high value or part of our
they had insufficient information to make a
critical infrastructure
decision on using PLP, with a clear lack of
The research has also contributed towards
settlements are remote and do not justify
expertise freely admitted even among flood
the development of new surveying proto-
expensive capital projects
risk management professionals.
cols for PLP technologies and a property
there is a history of inadequate drainage
To address this, a voluntary code of
or a drop in ground levels as occurred in
practice for the UK was co-produced with
Christchurch after the earthquake.
government departments, local councils,
Standards Institute.
flood resistance database for the insurance
industry.
regulators, flood risk consultants, product
Replicating the six steps in New Zealand
New field brings concerns
manufacturers, community flood resilience
Although this guidance will not be directly
Despite the potential of PLP, it has not
forums and the general public.
applicable to New Zealand because of its
been in common use. The European
Two separate guidance documents were
Union FP7-funded SMARTeST project was
developed:
funded to improve its contribution to flood
●●
management.
principles and methodology of the six steps
A comprehensive version for local authorities and professional flood risk managers.
The research established that the prob-
●●
A simpler version for property owners.
lems stemmed from a lack of trust in an
●●
approach is replicable.
The next move is for the extent of the
threat of surface water flooding to be recognised in New Zealand and for the guidance
Six steps identified
to be considered in this unique policy
how products and companies can be
In both versions, six sequential steps were
context.
compared
identified, beginning with understanding
For more
how to match the right product to the
the risk through to operation and mainte-
available from the Smart Flood Protection
right risk
nance (see Figure 3).
website at www.smartfloodprotection.com.
emergent field. Common concerns were:
●●
different regulatory circumstances, the
Step 1
Understand
the risk
Step 2
Planning a
scheme
Step 3
Property
surveying
Step 4
Design and
specification
Further information on the six steps is
Step 5
Product
installation
Step 6
Operation and
maintenance
Figure 3: Six-step process for property level protection.
Build 148 — June/July 2015 — 51