- Using spatial modelling to develop flood risk and climate adaptation capacity metrics for vulnerability assessments of urban community and critical water supply infrastructure   click here to open paper content820 kb
by    Espada, Rodolfo Jr & Apan, Armando & McDougall, Kevin | Rudolf.Espada@usq.edu.au   click here to send an email to the auther(s) of this paper
Short Outline
The aim of this study was to develop a new spatially-explicit analytical
approach for urban flood risk assessment and generation of climate
adaptation capacity metrics for assessing urban community and critical
water supply network vulnerability
Abstract
The aim of this study was to develop a new spatially-explicit analytical
approach for urban flood risk assessment and generation of climate
adaptation capacity metrics for assessing urban community and critical
water supply network vulnerability. Using the January 2011 flood in
Queensland (Australia) with the core suburbs of Brisbane City as the study
area, the research issues with regards to the sufficiency of indicating
variables and suitability of climate risk modelling were addressed in this
study. A range of geographical variables were analysed using high
resolution digital elevation modelling and urban morphological
characterisation with 3D analysis, spatial analysis with fuzzy logic, and
geospatial autocorrelation techniques with global Moran’s I and Anselin
Local Moran’s I. The issue on the sufficiency of indicating variables was
addressed using the topological cluster analysis of a 2-dimension self-
organising neural network (SONN) structured with 100 neurons and trained by
200 epochs. Furthermore, the suitability of flood risk modeling was
addressed by aggregating the indicating variables with weighted overlay and
modified fuzzy gamma overlay operations using the joint conditional
probability weights based on Bayesian theory. Variable weights were
assigned to address the limitations of normative (equal weights) and
deductive (expert judgment) approaches.

The analyses showed that 186 ha (8%) and 221ha (10%) of the study area were
exposed to very high flood risk and very low adaptation capacity,
respectively. Ninety percent (90%) of the study area revealed negative
adaptation capacity metrics (-31 to < 0) which implies that the resources
are not enough to increase climate resiliency of the urban community and
critical infrastructure (i.e. water supply network). This scenario was
further exacerbated by the findings that government infrastructures in
Queensland were uncovered by flood insurance. In the water supply network
vulnerability assessment, eight (8) out of 107 critical trunk-reticulation
main connection points were assessed as highly vulnerable critical water
supply assets. Furthermore, utility network analysis showed that turbid
water may flow along 246km of pressure main lines (i.e. trunk and
reticulation mains) covering the north east to north west sides of the
study area. In the absence of immediate mitigation measures, increased risk
of fluvial flooding to water supply may significantly impacted the health
conditions of urban residents.

The newly developed spatially-explicit analytical technique, identified in
this study as the flood risk-adaptation capacity index/metrics-adaptation
strategies (FRACIAS) linkage model, will allow the integration of flood
risk and climate adaptation assessments which have been treated separately
in the past. This study provides a tool of high level analyses (e.g.
building floor space, water supply connections, etc.) and identifies
adaptation strategies to enable urban communities and the water supply
industry to better prepare and mitigate future flood events. Furthermore,
the results generated from the model can be used to improve insurance and
land-use planning policies. These include the deliberation of risk-based
premium pricing of flood insurance that should not heavily based on the
geographic location of risk but should also take into consideration the
adaptation capacity (e.g. income, severe disability, poor access to
emergency services, etc.) of the community at risk. Through this approach,
the governments (i.e. local, state, and federal) may provide financial and
development support to areas of very high flood risk and very low
adaptation capacity; thereby strengthening public-private partnership. As
precaution, insurance policies may not be used solely as a decision tool
for urban development on areas of very high flood risk but also consider
the poor land-use planning inherited from the past. Further disaster risk
reduction measures identified in this study include the “flood proofing” of
residential houses and commercial buildings, implementation of “property
buy-back” scheme and “land swap” program, and amendment of Queensland
Development Code to regulate the construction of buildings on areas
identified with very high flood risk and very low adaptation capacity.
Keywords
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