Challenges for achieving sustainable flood risk
management
Author
Shah, MAR, Rahman, A, Chowdhury, SH
Published
2018
Journal Title
Journal of Flood Risk Management
Version
Accepted Manuscript (AM)
DOI
https://doi.org/10.1111/jfr3.12211
Copyright Statement
© 2015 John Wiley & Sons Ltd and The Chartered Institution of Water and Environmental
Management (CIWEM). This is the peer reviewed version of the following article: Challenges
for achieving sustainable flood risk management, Journal of Flood Risk Management, which
has been published in final form at http://doi.org/10.1111/jfr3.12211. This article may be used
for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving
(http://olabout.wiley.com/WileyCDA/Section/id-828039.html)
Downloaded from
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1
Title:
Challenges for Achieving Sustainable Flood Risk Management
Authors:
Mohammad Aminur Rahman Shah
1*
, Anisur Rahman
1
and Sanaul Huq Chowdhury
1
1 School of Engineering, Griffith University, Australia
*Corresponding author:
Mohammad Aminur Rahman Shah
School of Engineering, Griffith University, Australia
Email: m.shah@griffith.edu.au
Mailing address: School of Engineering (Bldg G09_1.02)
Griffith University, Gold Coast campus,
Parkland Drive, Southport, QLD 4222, Australia
2
Abstract
This paper presents the challenges for effectiveness and sustainability of flood risk
management strategies and technologies by critically reviewing flood management practices.
The study reveals that reliable flood prediction is limited by the characterization of floods
that have multiple causes and hydrological uncertainties due to variability in climate and
river morphology. Moreover, changing land use in floodplains and potential of creating new
risks limit the risk assessment and evaluation process of flood control projects. Hence,
sustainability analysis mechanisms, including ‘Dynamic Sustainability’ concepts, should be
adopted in the flood management planning process. Investigations into the proportional
contribution of structural and non-structural measures to reduce total flood risk could assist
in better decision making. Gaining improved understandings of the perception on flood risk
and safety, and risk communication methods, for present and future stakeholders, is crucial.
Extensive research on the above challenges would reveal pathways for developing
sustainable flood risk management strategies.
Keywords
Flood risk management, risk assessment, sustainability, flood control project
1 Introduction
Flood risk reduction is a prime concern for flood vulnerable countries around the world. Over
the centuries, in different regions, a variety of strategies and technologies for flood risk
reduction have evolved. Flood risk management processes, in general, include flood risk
identification, flood risk assessment, and structural and non-structural interventions to reduce
flood risk (McBain 2012). In all aspects of flood risk management, moreover, scientific and
technological advancements have been introduced, although many critical issues are yet to be
solved. Similarly, flood risk reduction policies and strategies have shifted from localized,
reactive and isolated approaches to regional, integrated and proactive approaches (Sayers et
al. 2012). With the progress of scientific knowledge and international collaboration, similar
strategies and technologies are being applied around the world, and customized based on
geographical and socio-economic contexts.
Despite all international efforts and technological advancements, flood risk management
remains a challenging task for many developed and developing nations. This situation is
particularly salient in light of unprecedented flooding events occurring in flood protected
areas in recent years, believed to be triggered by global climate change (Kelman 2001;
Melillo et al. 2014). Additionally, more frequent and catastrophic floods are expected in
future. Also, currently practiced flood risk assessment processes seem to have gaps, which
have led to improper planning and design of flood risk reduction measures, and,
consequently, function ineffectively during various catastrophic flood events.
Scientists have been examining the present knowledge base of flood risk reduction strategies
and technologies to identify the gaps and to strengthen the processes. Such efforts have been
made in the current study which critically reviewed the strategies and technologies applied to
flood risk reduction in different regions. The historical background of the strategies and
changes, made over time, have been critically examined in the context of achieving greater
effectiveness and sustainability in the strategies, both in terms of technology and societal
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development. The study also examined cases of flood mitigation measures implemented in
different floodplains to discover the gaps in the planning and implementation process. This
critical examination revealed new dimensions in developing future flood risk management
strategies. More research and development needs to be carried out on the identified gaps to
minimize future flood risk.
2 Dimensions of flood risks
Floods, as one of the most common natural hydrological hazards, have been occurring in
floodplains over millennia. They are caused by river overflows, heavy rainfall, tidal surges,
snow melts, and groundwater seepage. In recent times, severe floods have occurred in China
(1998: Yangtze River, 2013: Southeast China), Central Europe (1997, 2005), the United
Kingdom (2000, 2007, 2009), Bangladesh (1988, 1998, 2007), the United States of America
(USA) (2005: New Orleans), and Australia (2011: Queensland) (Sayers et al. 2012; QFCI
2012). Predictions on changing climatic conditions and rising sea levels suggest, in the near
future, more catastrophic flooding in some parts of the world (IPCC 2014). Many areas have
already experienced increased flooding due to climate change (e.g. USA), in areas where
there were no earlier severe flooding (Melillo et al. 2014).
Irrespective of the causes and nature of the floods, the elements impacted by flooding are
common: human life and livelihoods, settlement and housing, agriculture, industries,
commercial activities, and communication infrastructures. Usually the major urban
settlements that develop along rivers are particularly at risk of flooding, especially as the
pattern of flooding and risk elements are changing spontaneously through rapid land use
conversion and urban development. Rural areas are also affected by flood; it is mainly
agricultural economies and livelihoods that are disrupted (Islam, 1997; Messner and Meyer
2006).
The characteristics of a flood and the vulnerability of the elements in the floodplain to the
particular flood events appear to determine the risk to the elements. Defining flood hazards
through meteorological, hydrological, and hydraulic investigations, as well as determining
the vulnerability of elements, by estimating the impact of floods, can be carried out
separately. However, then, both hazard and vulnerability have to be combined for the final
risk analysis (Mileti 1999; Merz and Thieken 2004; EU 2007; Wu et al. 2011). Sayers et al.
(2012) have further elaborated the fundamental concept of flood risk by defining the multiple
dimensions of risks covering the dimensions of flood characteristics, i.e. source and
pathways of the water that determine the probability of flooding; whereas the consequences
of a flood are determined by the exposure and vulnerability of the receptors. Such
vulnerability depends on the value, susceptibility, and resilience of the receptors.
3 Complexities in flood risk assessment
Flood risk analyses are gaining more importance in the fields of infrastructure design and
flood management. These analyses enable agents to evaluate the cost-effectiveness of the
flood control projects and provide risk information to residents, insurance companies, and
municipalities to prepare for disasters (USACE 1996; Olsen et al. 1998; Al-Futaisi and
Stedinger 1999; Ganoulis 2003; Merz and Thieken 2004; Hardmeyer and Spencer 2007).
Several models and analytical methods are now available to identify and define flood
hazards, vulnerability, and flood risk. Over the years, the simple approach of defining flood
events, with a return period through frequency analysis (Stedinger et al. 1993), has been
transformed to more complex methods to determine probabilistic flood scenarios with
consideration for exceedance probability (Merz and Thieken 2004) and uncertainties (Merz et
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al. 2008; Wu et al. 2011). Advances have been made in regional flood frequency analysis
(e.g. Bayesian Generalised Least Squares (BGLS) regression in a region-of-influence (ROI)
framework was developed for regional flood frequency analysis in eastern Australia)
(Haddad and Rahman 2012; Nguyen et al. 2014). Moreover, linear interpolation models to
complex 1D/2D hydraulic models are now being used to analyse the extent of a flooding and
inundation area (Apel et al. 2009).
Also, in light of the increasing understanding of flood characteristics, approaches to
vulnerability analysis have been transformed. Vulnerability analysis has developed from a
simple calculation of flood effects, by stage-damage function (Smith 1994), to more
comprehensive assessments of flood effects. These effects include, for instance, inundation
depth, flow velocity, inundation duration, flood warning, and response (ICPR 2002; Kelman
and Spence 2004; Kreibich et al. 2005; Penning-Rowsell et al. 2005; Thieken et al. 2006).
Further, flood loss estimation techniques are available on a micro to macro scale. A micro-
scale loss analysis can be undertaken in small areas with detailed information about types and
use of individual buildings and structures. In contrast, a meso/macro scale approach is
suitable for large areas, as it is based on aggregated land cover categories linked to specific
economic sectors. The loss in each sector is then aggregated to estimate the total damage
(Messner and Meyer 2006). While most of the damage assessment functions provide results
in monetary terms related directly to quantifiable buildings/infrastructures, some methods
provide relative loss functions, for instance, loss in the percentage of the building or content
value (Dutta et al. 2003; Thieken et al. 2006), or as index values, such as loss expressed as an
equivalent to the number of median-sized family houses totally destroyed (Blong 2003). An
enhanced understanding of flood risks has revolutionized traditional flood risk reduction
measures by decreasing the probability of floods through mounting a structural defence
encompassing all dimensions of flood risks (Sayers et al. 2012).
4 Analysis of current flood risk management strategies and technologies
Flood risk management strategies and technologies have evolved over centuries with the
development of civilizations in different parts of the world. The earliest civilizations settled
along rivers or floodplains, with critical infrastructure and houses being located on higher
ground. These settlements also adapted to floods by the population choosing flood sensitive
economic, social and cultural activities (Sayers et al. 2012; McBain 2012). Since the early
20
th
century, structural engineering solutions have taken a key role in flood risk management,
as the demand has continued for human safety, food security, and safe urban and rural
development.
During the 1960s to 1980s, the construction of embankments, dykes, polders, diversion
channels, dams, and similar structures were the main flood mitigation and control measures
to be used. Alongside structural measures, non-structural measures have been used, including
reducing the severity of flooding through land use changes in upstream catchments,
increasing preparedness through early warnings, and reducing the consequence of flooding
by reducing both exposure and vulnerability (White and Richards 2007; Richards et al. 2008;
Tapsell 2002). Historical evidence suggests that flood risk management began and developed
from a willingness to live with floods when there was limited technology. However,
population pressures and food shortages have forced societies to utilize floodplains and,
therefore, to control floods with structures. In recent years these strategies were followed by
both increasing efforts to reduce flood damage and addressing whole risk management
(Sayers et al. 2012; McBain 2012).