Rapid decision support tool based on novel ecosystem service variables for retrofitting sustainable drainage systems in the presence of trees

Uzomah, VC

Abstract

There is a lack of practical decision support tools useful for a rapid assessment of
the potential of ecosystem services when retrofitting permeable pavements in urban areas
that either feature existing trees or should be pla
nted with trees in the near future.
There is
also a need for a geospatial decision support tool for different professions such as drainage
engineers and urban planners, which is useful for a quick assessment of the potential of
ecosystem services when retr
ofitting sustainable drainage systems (
SUDS
) in urban areas
Therefore the aim is to develop a
decision support tool for choosing the best possible
options for the
retrofitting of
su
stainable urban drainage system techniques
using novel
ecosystem service
variables and modify
it
to include
a
reflection of the confidence level of
the
assessor
to minimise uncertainty
,
and
weighting factors that will reflect the
pr
ofessional background of the
stakeholder
s to reduce professional bias
.
This
tool was
developed and
used to assess 100 sites in Greater Manchester with
retrofitting
potentials including Brownfield sites
.
The introduced weighting factors helped
to
narrow down the choices
further.
Since the retrofitting of
SUDS
, especially permeable
pavements
, and other urban development projects usually involve areas where there are
already existing mature trees, further studies were carried out on the damage
characteristics of urban tree species on urban structures including permeable pavements,
impermeable
pavements, kerbs, roads and retaining walls. This was conducted on a
different 100 sites also in Greater Manchester. Further studies were also carried out about
public acceptance of the urban tree species using pictures taken of trees from the
Westonbirt N
ational Arboretum.
The result
s
of the ‘ecosystem service’ approach
were compared with those
of
traditional
‘community and environmental
’
approach
developed by CIRIA.
A comparison
with the traditional approach of determining community and environment variab
les
indicates that permeable pavements are generally a preferred
SUDS
option regardless of
the professional perspectives
.
The introduced w
eighting factors
made the tool
lend itself to
be used by stakeholders of varying professional backgrounds.
The results of the
comparison of the different approaches showed that the ‘ecosystem service’ approach gave
a rather more thorough and precise assessment and will give a less misleading choice of
SUDS
techniques.
In comparison to common public opinion, sta
tistically significant
differences between social scientists and the general public for the estimation of
land costs
using the non
-
parametric Mann
-
Whitney U
-
test were found. It was also surprising to find
no significant differences in the estimation of
hab
itat for species
by civil engineers and
xviii
ecologists.
Permeable pavements combined with urban trees received relatively high
scores, because of their great potential impact in terms of water and air quality
improvement, and flood control, respectively.
The
r
esult
of
the assessment
of damages to structures by urban tree species
revealed that Norway maple, Lime, Common Ash and Sycamore dominated Greater
Manchester, and
showed that certain tree species are better suited for certain structures
either beca
u
se of
the damage or the nuisance that the trees cause
. Impermeable pavements
were subject to the highest number of damage from trees (44%), followed by permeable
pavements and kerbs (22% and 19%, respectively).
Trees planted close to impermeable
pavements will c
ause more damage to the structure compared to those planted close to
permeable pavements under the same conditions. Wild cherry, large leaved lime, horse
chestnut and hawthorn may are the best recommended trees for use alongside
most
roads
and
SUDS
structu
res as they have least potential to damage structures. However, horse
chestnuts produce lots of litters with their conkers. From aesthetics point of view,
sycamore was the most aesthetic tree all
-
round the year
.
This study therefore suggests best tree spec
ies for permeable pavements and other
related structures, and its outcomes are likely to lead to more combined permeable
pavement and tree systems in the urban landscape, which are beneficial for humans and
the environment.
It will help urban developers in
choosing the most suitable trees for the
right urban environment. It will also help to save money in maintaining infrastructure such
as roads and pavements.
Keywords
:
Sustainable urban drainage systems; Ecosystem services; Permeable
pavements; Expert
system; Different professions;
Stakeholders;
Uncertainty; Urban trees;
Urban structures, Structural damage.

• Thesis Type: Thesis
• Acceptance Date: Jan 28, 2016
• Deposit Date: Jun 17, 2016
• Publicly Available Date: Jun 17, 2016