The proposed framework integrates major points of the flipping coin (vulnerability and
resilience are normalized as stress and resources, and they are two sides of the same coin) and
separation concepts (vulnerability and resilience both can generate positive and/or negative
outcomes) to address the dynamic interactions between ecological vulnerability and resilience
prior to and during floods. Ecological vulnerability involves a wide array of stress types
resulting from human-nature interactions. When these concepts are equivalent, it is easy to
explain the momentum of the system using the multi flipping-coin approach. The proposed
framework however relies on available data and the participation of the stakeholders.
Even when separating ecological vulnerability from resilience (which allows explaining
their dynamic interactions) the proposed framework has explicit limitations:
• The framework is limited in designing accurately the maximum stress and resources.
This has to do with the available data in the study areas. Data can assist quantifying the
depth and height of creative and resistant regimes.
• The specification of a regime is always temporal because environmental, social and
economic processes are dynamic and lead to changes in the state of the system.
• Stakeholders help deciding on stress and resources indicators and their state.Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
632
• Conceptualizing ecological vulnerability will make the exercise complex, as it has to
deal with: (i) covering stress during and prior to the floods, and (ii) defining variables
and state of the environmental, social, and economic processes both prior and during the
flood.
• The framework does not focus on long term effects from prior to post-flood scenarios
because determining flooding periods is local specific. However, once the momentum
between pre-floods and the actual conditions of the system at risk is established, direct
causes and solutions for dealing with the flood are provided. The proposed framework is
also applicable for post-flood evaluations. As long as the pre-flood and flood conditions
are examined, post-flood can be properly handled. The 2005 flood in New Orleans (US)
provides an example.
• The focus should not be on urban areas alone. However, in developing countries,
urbanization and population growth affect agricultural land use quite dramatically. Lowincome citizens often attempt to settle in floodplains where drainage systems are, as a
rule, outdated. The theory addressed by this paper is applicable for both rural and urban
areas. Urban or rural resilience is “in se” not different.
• The framework does not provide solutions for cross-scale measurements.
Further studies should explore more knowledge to improve the framework. Additionally,
one should pay attention to selecting variables and cross-scale measurements. Selecting
appropriate sets of variables for ecological vulnerability and resilience assessment is a daunting
task as there is currently no standard. The issue has two major aspects: One is how many
variables are enough? And the other one is about which variables characterize best stress and
resources? This second aspect re-addresses the crucial role of the stakeholders in the evolution
of the system because some resources can amplify stress. Designing spatial units for cross-scale
measurements is equally important. Scaling the system up and down between different policy
levels requires advanced GIS and Remote Sensing techniques to address the MAUP.
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eractions between ecological vulnerability
and resilience, this paper provides answers to questions on how realizing their separation. This
allows describing the momentum of system changes prior to and during a flood. The interactions
generate multiple flipping-coin effects over a geospatial space.
2. VULNERABILITY
Vulnerability is a multifaceted concept of which the content varies across disciplines and
organizations. It often reflects a series of environmental and socio-economic indicators, which
are dynamic due to changes in natural systems or to human interactions [5, 18 - 21]. The current
literature does not provide a standard for vulnerability assessment. Nevertheless quite a complete
conceptual framework has been developed covering all essential aspects of vulnerability that are
useful to be applied in flood risk management [22].
A variety of definitions of “vulnerability” exists. UNISDR [23] for example, refers to
vulnerability as the susceptibility of social, economic and environmental aspects [23]. Schanze
[20] sees vulnerability as the intrinsic characteristics of elements, which are prone to harm. He
points to three basic sustainability dimensions of flood vulnerability: social (including cultural),
economic and ecological vulnerability. Dewan [24] lists three major premises of vulnerability:
(i) Vulnerability as an outcome of the hazard and characterized by exposure, sensitivity, and
potential consequences. This approach is based on the risk and hazard paradigm of human-
nature interactions. (ii) Social, environmental and cultural aspects of communities or individuals
to determine why a particular community is vulnerable and why harmful effects of hazards on a
Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
622
community are unevenly distributed. (iii) The third presumption uses “sustainable development”
and emphasizes self-healing of socio-ecological systems [5]. Bizimana and Schilling [25] dissect
flood vulnerability in its physical, social and economic dimensions and their (composite)
interactions. Physical vulnerability focuses on the fragility or weakness of the exposed objects to
the flood hazards. Social vulnerability is associated with the lack of skills and resources to
prevent, cope with and/or recover from the hazards. Economic vulnerability relates to financial
values and primarily refers to low-income citizens who often live in floodplains and lack the
support of the local governments [26]. Therefore, it is important determining how well
communities are prepared to adapt to or to cope with floods during all stages of the management
cycle. Composite vulnerability is a concept of increasing importance in the current scientific
research. It refers to physical, social, economic and environmental factors. Composite
vulnerability shifts the focus from physical and social effects of floods to a wider understanding
of vulnerability as a process, and a dynamic product of socio-economic and environmental
convergences, which vary over space and time [27]. In other words, composite vulnerability
refers explicitly to the connections between harmful effects and the coping capacity based on the
socio-economic, ecological and demographic background of the exposed communities and/or
individuals [28].
Figure 1. The BBC conceptual framework was designed as a monitoring system for environmental,
social, and economic spheres. When a hazard occurs, the vulnerability in environmental, social, and
economic aspects of the exposed elements will be calculated. A feedback loop returns information about
disaster management to intervention system for future hazards [29 - 31]. Limitations of the framework:
(a) no information on scaling effects, (b) vulnerability is only calculated based on the incidents, and
(c) management phases may overlap in practical applications.
An in depth review of different vulnerability concepts refers to the BBC framework which
was established by Bogardi and Birkmann [29], Cardona [30 - 31] (Figure 1). The model takes
into account social, economic and environmental dimensions. The BBC framework analyzes
A systematic approach to the dilemma between flood vulnerability and resilience - review and concepts
623
vulnerability in a context of capacity and pro-activity of intervention measures [32]. These pre-
interventions are particularly crucial in flood risk management, as they significantly influence
the cost of flood responses and recovery. Three major drawbacks of the BBC concept are: (i) It
does not scale effects as environmental, social, and economic components. (ii) Vulnerability is
calculated just as a hazard incident; this does not cover adequately the complete human-nature
interactions [17]. (iii) The flood management cycle is an obsolete concept [33]. The purpose of a
management cycle is among others to allocate appropriate responsibilities of those who are
involved. In a spiral development, some complex events need to coincide for example, a single
large-scale disaster may relate to a number of small and medium disasters. When a disaster
occurs, many participatory sectors will find themselves at different stages of the cycle at the
same time [24].
3. RESILIENCE
Both vulnerability and resilience are central concepts providing frameworks for mitigating
adverse consequences of hazards. Just as vulnerability, resilience entails social, environmental,
and economic components, which change over space and time. However, resilience refers to
resources and systems responding to disturbances. Resilience is the capacity of a system to
absorb and cope with disturbances in the short-term and to reorganize and improve this capacity
during a long-term period without losing the system's services [3]. Resilience of a community to
flood is a process in which capacity building or enhancement responding to different magnitudes
of the disturbance varies across flood stages [21].
Figure 2. Comparison between engineering and ecological resilience. a) Engineering resilience refers
to the movement of a system around its stable equilibrium. b) Ecological resilience refers to multiple
equilibria. The balance of a system depends on the challenges of disturbances and resources.
The system can leave the existing regime and move to a new equilibrium [35].
Overall, there are two major approaches to resilience: an engineering and an ecological one
[34]. Ecological resilience reflects the dynamics of the system (Figure 2b). Engineering
resilience (Figure 2a) refers to the ability of a system returning to a stable equilibrium after a
shock. It focuses on protecting the functional stability of engineering systems. Engineering
resilience assumes only one regime and considers whether the system can resist at the very
bottom of the regime [34]. The speed with which the system returns to the equilibrium depends
on four aspects: the physical strength to tolerate disturbances without losing the system's
functions, the ability to quantify the threats and allocate resources, the ability to substitute the
components of the system, and the internal coping ranges by which the system can be restored
timely [35]. Resistance of engineering systems is crucial in explaining why resilience may be
Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
624
positive (e.g. absorbing shocks) or negative (e.g. resist system's changes). In practice, the
approach of engineering resilience is problematic because the interactions between disturbances
and resources will re-configure the current system to establish a new, more optimal reference
state eventually far from a steady equilibrium [16].
Table 1. Comparison between engineering and ecological resilience.
Engineering resilience Ecological resilience References
Theoretic
construct
Resilience = resistance +
recovery
Resilience = tolerance +
reorganization
[35]
Types of
equilibrium
One equilibrium (one
regime)
Multiple equilibria
(multiple regimes)
[16, 35]
Pre-conditions Stability near equilibrium Far from equilibrium [6, 16]
Focus • Speed to return to the
equilibrium
• Protect the existing
configurations of the
system
• Detect the
engineering
equilibrium
• System evolvement
through multiple
equilibria
• Explore modifications
of the system
• Detect regimes
[16, 35, 36]
Roles of shocks Threats Learning opportunities [35]
Properties Robustness, redundancy,
resourcefulness, rapidity
Self-organization,
adaptive capacity
redundancy
[16, 35]
Measurement
scale
Quantitative Mainly qualitative [6]
Variables Functional variables Slowly-changing
variables
[6]
In contrast to engineering resilience, ecological resilience explores the tolerance and re-
organization of the system through multiple equilibria (Table 1). Ecological resilience relates to
(i) the capacity to absorb disturbances, (ii) the preparedness for other flood events, and (iii) the
integration of multiple resources [35]. Self-organization, refers to the coping capacity in which
the internal ability of the system allows a quick re-organization and resolving disruptions
without external resources. A second characteristic of ecological resilience concerns the adaptive
capacity contributing to resilience in the long-term, as it indicates the ability to learn from each
flood and to adjust the system to internal and external changes. The last one, redundancy of
ecological resilience, refers to the diversity of opportunities from various disciplines and
institutes to enhance long-term adaptation [37].
4. THE VAGUE BORDERS BETWEEN VULNERABILITY AND RESILIENCE
Three main schools of thought exist when it comes to distinctions between vulnerability and
resilience in a context of risk management: (i) they are two sides of the same coin, (ii) resilience
A systematic approach to the dilemma between flood vulnerability and resilience - review and concepts
625
is part of vulnerability, and (iii) both are distinct concepts with some overlaps (Table 2). The
first one focuses on risks and benefits of management, while the second characterizes the
dynamics of vulnerability when a system is exposed to flood. The third one takes into account
the heterogeneity of stakeholders' strategies [13,16]. Regardless of the attempts to define and
measure vulnerability and resilience, the analyses about how vulnerability interacts with
ecological resilience are still vague and remain challenging.
Table 2. Comparison of vulnerability and resilience.
Ty
pi
ca
l p
o
in
ts
Two sides of the same
coin
Resilience as a part of
vulnerability
Separated concepts with some
overlaps
• Vulnerability as stress
• Stress occurs when
resources are
threatened, lost or
individuals fail to get
resources
• Vulnerability is
associated with a
'negative' notion,
while resilience is
associated with a
'positive' notion
• No community is
always vulnerable or
resilient
• Resilience and
vulnerability
complement each other
in sustainability science
• Resilience focuses on
the capacity of the
system to return to the
original state after a
shock
• Vulnerability =
exposure +
susceptibility + adaptive
capacity
• Focus on detecting the
system's capacity ranges
to reduce potential
vulnerability
• Both are processes driven by
interactions between human
systems, environmental
systems and the built
environment
• Vulnerability refers to
weakness and fragility while
resilience involves
effectiveness of adaptations
• Resilience can be either
positive (e.g. absorb shocks) or
negative (e.g. prevent system
changes)
• Types of governance
(utilitarian, libertarian,
communitarian, etc.) amplify
various contents of resilience
R
ef
er
en
c
es
[1, 5-7, 37] [8, 9, 10, 11, 22, 38] [2, 4, 12-16, 39]
4.1. Flipping coin
The first school of thought uses system theory to explain the contradiction between
vulnerability and resilience. As long as both concepts rely on the same elements, they are two
sides of a flipping coin [1, 5, 6, 7, 37]. Both concepts are considered as opposite because one is a
stress or harm for the system, while the other protects the system's functions [7]. According to
Wilson [1], they are opposite ends of a spectrum; therefore, weak resilience results in high
vulnerability. This contradiction applies when vulnerability and resilience are internal states of a
system which exists independently of the external hazards [40]. In the case of flood,
vulnerability depends also on external factors as exposure and sensitivity, which change the
system's structure and its components [2]. Consequently, pre-defined vulnerability and resilience
prior to the flood are no longer seen as opposite during the calamity.
Conventional flood risk management often focuses on calculating the vulnerability at the
time the hazard occurs, ignoring that vulnerability is a multiple stress determined by social,
economic, and environmental conditions before, during and after the flood. For example, the
Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
626
effects of the 2005 flood in New Orleans, US persisted during months after the water receded
[41]. Stress of floods on a local community is more intense if the pre-flood vulnerability and the
flood exposure are combined [7]. Vulnerability and resilience are not always correctly described
by 'negative' and 'positive' impacts, respectively because e.g. resilience may be a negative factor
if it obstructs system changes [39]. The same applies to vulnerability. For example, periodic
floods provide nutrients to agricultural fields [35]. The concepts 'bad vulnerability' and 'good
resilience' depend on time, scale and context. They reflect aspects of the dynamic interactions
between vulnerability and resilience in a community. A community is not a homogeneous entity
because its individuals and stakeholders use different resources and strategies to cope with stress
[1]. Some stakeholder's resources might be contradicting with those of others; therefore,
resilience for a part of a community may turn out negatively for another group [39]. The
multiple resources a community uses explain why the relations between vulnerability and
resilience are not linear.
4.2. Resilience as part of vulnerability
The second school of thought focuses on resilience as an element to reduce vulnerability.
The dynamic process of vulnerability across scale and time is analyzed, while admitting that
exposure and capacity are two components of vulnerability. Therefore, when there is no flood
and thus no exposure, vulnerability can be measured just by resilience. Consequently, this
approach does not acknowledge that vulnerability and resilience exist in any system [1].
Füssel [8] examines the cross-scale vulnerable of a system independent of particular
research traditions, as those of socio-economic systems [42] or coupled human-environment
systems [10]. It is noteworthy that hazards are not always defined as the external causes of
adverse effects on the system, but sometimes as internal causes. For example, land use planning
may result in an unsustainable development of a community [8]. Therefore, environmental,
social and economic attributes of a focal system should also be examined at coarser and finer
levels. This is the main reason to classify system properties in multi spatio-temporal scales. Even
if the method acknowledges the existence of vulnerability in multiple disciplines and spatio-
temporal scales, the approach is hampered by delineating internal and external factors, which
cause confusion. For example, national economic indicators are internal for a national
assessment, but external to a city. Efforts to enhance the capacity of the community dealing with
multiple stress factors are always a central concern. Jacobs et al. [38], Smit and Wandel [9], and
Yohe and Tol [11] point to the variability of resources and the ability of a system to use them
effectively. Lastly, both vulnerability and resilience are non-linear processes, cross-scale
alterations, and subject to multiple changes by stakeholders [10]. Overall, the second school of
thought puts a focus on risks deteriorating the functions of a system, rather than describing the
dynamics between vulnerability and ecological resilience within the interactions of human and
environmental systems, and the built environment [12].
4.3. Separated concepts with overlaps
Even when vulnerability refers to the fragility of a system for shocks, and resilience is
about the ability to absorb shocks and to protect the functions of a system, they are not
necessarily two sides of a coin. This is because they are characterized by indicators reflecting the
objectives of the stakeholders. In a specific context, time, and scale, resilience may produce
negative outcomes [39]. If the flipping-coin concept defines indicators based on outcomes rather
than on processes, they cause confusion between vulnerability and resilience. For instance, a
A systematic approach to the dilemma between flood vulnerability and resilience - review and concepts
627
static indicator as income per capita, does not represent functional processes of vulnerability or
resilience over time. A better indicator is the proportion of the employed labor force [43].
Stakeholder involvement is important to reduce conflicts in flood management strategies
[42-43]. A set of characteristics allowing to compare vulnerability and resilience across scale
and time, can only be applied if the stakeholders agree. Priority indicators can be defined, which
can be ranked according to their importance, and possible overlaps can be avoided. Vulnerability
might be used for short-term impacts of specific risks, while resilience covers the broad
spectrum of impacts and adaptations [3]. These differences mean resilience works well in a
dynamic environment and can contribute to better decisions under uncertainty. The literature
shows a consistent agreement when it comes to recognizing that both concepts refer to dynamic
processes relying on multiple contexts, time, scale, and stakeholder involvement [2,5,8,44].
Therefore, some indicators include components of both vulnerability and resilience [13,16]. For
instance, a household income can contribute to resilience and/or to vulnerability. High-income
families might invest in the physical quality of their houses or purchase an insurance to increase
their social resilience while decreasing their vulnerability to flood. At the same time low-income
groups might neglect these instruments. Consequently, their socio-economic status continues
showing a high vulnerability and/or a low resilience. Even when one understands the differences
between both concepts, their overlaps are hard to detect. They depend on which adaptation
strategies generate negative effects. For instance, a dyke might increase resilience to flood of a
community in stable situations. But, when floods happen, the dyke might break. This
consequence might combine with other unpredictable weather conditions to intensify the
vulnerability of the community [35]. Adapting the resources to the objectives of the stakeholders
modifies the capacity of the system to cope with disturbances.
Also governance options and policies affect the use of resources [15] . For instance, liberals
tend to consider that individuals have their own responsibility improving their adaptation
capacity. Socialists on the contrary, prefer public rather than private strategies towards
adaptation, because this approach favors equity. Therefore, adaptation strategies of a particular
nation cannot just be transferred to another country. Within each community, a variety of
stakeholders is involved in flood risk management: their individual strategies can be redundant
or even contradictory [1].
In conclusion, resilience shows a wide range of aspects which partially overlap with
vulnerability. Therefore, defining appropriate indicators for vulnerability and resilience is a
daunting task with challenging aspects: Which indicators of vulnerability overlap with the
resilience ones? Is there a common set of vulnerability and resilience indicators that can be used
to assess and compare community resilience to flood across space and time? Overall, this third
school of thought focuses on the heterogeneity of selecting vulnerability and resilience
indicators driven by the objectives of the stakeholders. The dynamic interactions between
vulnerability and resilience are still vague and rely on how well one succeeds in specifying the
indicators.
5. CONCEPTUAL FRAMEWORK INTEGRATING THE DYNAMIC INTERACTIONS
BETWEEN ECOLOGICAL VULNERABILITY AND RESILIENCE
The lack of a clear vision on ecological vulnerability results in vague comparisons between
the three approaches. Ecological vulnerability emphasizes the importance of an assessment of
the pre-flood and flood conditions on their environmental, social, and economic aspects [46]. As
hazards for any community are driven by the interactions between the human and the natural
Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
628
systems [12,17], ecological flood risk assessment makes vulnerability - resilience relationships
more transparent.
5.1. Interactions between ecological vulnerability and resilience
Examining ecological vulnerability and resilience, allows detecting the wide spectrum of
interactions between multiple stress events and resources across contexts, scale, time and
stakeholder involvement. This concern applies to the assessment of any type of hazard [36,45].
In an ideal, simplified context, ecological vulnerability and ecological resilience are opposite
[17]. Ecological vulnerability refers to stress that might originate from many sources, including
non-flood related incidents [46]. While ecological resilience describes the changes of adaptation
and coping capacity in multiple regimes across scale and time, vulnerability as defined by all
schools of thought is not symmetrical to ecological resilience. The first school of thought
considers vulnerability and resilience as two sides of a flipping coin. This school ignores that
pre-flood environmental, social and economic conditions modify the outcome (positive or
negative) of vulnerability [46]. The second school of thought calculates vulnerability only during
flood incidents. Although the third school of thought deals with vulnerability as a dynamic
process, the pre-flood interactions between vulnerability and resilience remain vague. Dealing
with these drawbacks, a new framework combining the first and third school of thought has been
established. In general, ecological vulnerability and resilience are normalized as stress and
resources over scale and time. Their interactions within environmental, social, and economic
aspects evolve in a non-linear way from pre flood to flood situations. Major points of the new
framework are:
• Ecological vulnerability and resilience will be presented in terms of stress and resources.
This point is based on the work of Norris et al. [7] and Wilson [1]. Their separation as two
sides of the same coin allows simplifying the definitions of vulnerability and resilience.
However, one should keep in mind that both vulnerability and resilience can generate
positive and/or negative outcomes [39].
• At a specific scale and time, regardless of flood, ecological vulnerability and resilience
indices of a measurement unit (e.g. a county) are composites of a wide array of stress events
and resources with environmental, social and economic aspects. As mentioned by the third
school, stakeholder agreement on indices is crucial to distinguish between vulnerability and
resilience. Defining a measurement unit is equally important because this assists in
delineating the boundaries between focal, and upper and/or lower systems [42].
• To quantify the flood assessment, stress and resource indicators must be normalized to the
same scale, e.g. using a min-max scaling [13]. Environmental, social, and economic
indicators contain both quantitative and qualitative aspects. Using the same scale helps
quantifying composite stress aspects and resources during pre-flood and flood.
• To understand the momentum of the system from pre-flood to flood, the stress over
resources ratio is calculated. Unlike the three schools of thought relying on flood incidents
and calculate flood risk based on 'minus' and/or 'plus' between vulnerability and resilience,
the ratio allows (i) determining 'how much' to which extent the system will move, and (ii)
when and where there are needs providing additional resources to achieve the equilibrium
of the system (see Figure 3). For a specific context, time and scale, if stress and resources
respectively generate positive and negative outcomes, the stress and/or resources will be
amplified. For another context, time and scale the ratio continues to show two sides of the
A systematic approach to the dilemma between flood vulnerability and resilience - review and concepts
629
same coin. The first school of thought considers only outcomes, and therefore, cannot
reflect on dynamic changes of stress and resources and its analyses are not transferrable.
• The stress over resources ratio allows detecting resistant and creative or flexible regimes
and thresholds. In a resistant regime, the stress is larger than the resources. In a creative-
flexible regime, the opposite applies. The thresholds cover a range of values around 1
depending on the available data and the decisions of the stakeholders.
• The distribution of the ratio in a defined space generates multiple regimes and thresholds,
which lack in the first school of thought.
Fig 3. The distribution of stress over resources ratios at a specific scale and time. The ratios vary across
geographical areas. The equilibrium value between stress and resources is 1, also called the recovery
threshold. Besides the equilibrium is regimes, in which stress is higher or lower than the resources. A
regime is creative when the ratios are smaller than 1 (more resources than stress) while it is resistant if the
ratios are greater than 1 (more stress than resources). The regimes are characterized by depth, height and
extent. The red point is the minimum ratio between stress and resources within a creative regime. The blue
point is the maximum height coinciding with the maximum ratio in a resistant regime. The more the
height or the depth is, the more energy the system needs to change within the regimes. The extent
connects recovery thresholds between regimes. It defines the maximum change a system can take before
shifting to another regime. The larger the extent is, the slower the shift can achieve. After Beroya-Eitner
[17], Frommer [2], and Walker et al. [47].
Figure 3 illustrates the dynamic interactions between stress and resources for a specific
scale and time frame. Location specific strategies for sustainable development of communities
require defining thresholds and regimes of the interactions between stress events and resources
[17]. For any specific context, time, and scale, the relationships between stress and resources can
be characterized as a state of recovery, creativity, or resistance [2]. The balance between stress
and resources defines the recovery capacity of the system. A regime characterizes unique
behavior and functions of the observed system influenced by specific hazards [35, 46]. For
instance, soils in countries along the Alpine-Carpathian Mountains respond in a variety of ways
to floods [48]. If the system has access to abundant resources to deal with stress, it is a creative
regime. A regime is resistant when its coping capacity does not allow adapting to adverse events
[17, 49, 50]. The extent and the depth or height are important characteristics of a regime. The
extent connects recovery thresholds between regimes. It decides the maximum changes of a
system before losing its ability to recover [2, 47]. Under a creative regime, the extent indicates
Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
630
the maximum stress to balance with the resources. In a resistant regime, the extent specifies the
maximum amount of resources, which allows eliminating the stress. The depth or height
represents how difficult or easy to the system changes [47]. Depending on the available data,
multiple levels of minima and maxima exist in a defined space.
5.2. The dynamics of the system before and during floods
Analyzing the movement of the system between flood and non-flood situations necessitates
an adequate information system with data on all the main states of environmental, social, and
economic indicators across scale and time. Local applications are best characterized by specific
indicators. Every area has its own indicators which cover environmental, social and economic
aspects. In this context, Cutter et al. [51] published a list of more than a hundred indicators. The
state of the system is described by variables of the system [47]. For instance, an ecological
system in a floodplain is characterized by both environmental (e.g. soil moisture, water quality),
and socio-economic indicators (e.g. land use and age of the population). To quantify the
responses of the system to flood, stakeholders will collect data and decide the state of each
indicator under both flood and non-flood situations (section 4). A simplified state of the system
might be described by: soil moisture (low, high), water quality (clear, turbid), land use
(agriculture, bare land), and age (under 18, over 18). It is essential that stakeholders agree on
defining the state [43] which characterizes the system. Once one indicator changes, the whole
system changes, e.g. water changes from clear to turbid due to flood [52].
Fig 4. Movements of the system within and between regimes. The arrows indicate moves to particular
states of the system. The dotted blue line defines regimes with different characteristics as compared to the
solid one (black line).
Studies on flood risk management often quantify vulnerability during the flood. As a
consequence, they do not cover the whole range of stress from pre-flood to flood situations and
only prepare for part of the upcoming adverse consequences. Suppose that during a stable pre-
flood situation a community is well protected by infrastructure, keeping the risk under control
[35] and the economic, social, and environmental context is acceptable. The absence of one of
these vulnerability aspects will cause stress on the community even when there is no flood [1].
Under non-flood conditions the system likely moves within the designed regime and there is no
need for a regime shift. Without a flood the system might use external resources [8]. In theory it
is even possible that the system moves into the creative regime at locations 1 or 2 of Figure 4.
However, the gradual shift to another regime is possible if the stress is not addressed in the long-
term [46]. Regardless of flood, the socio-economic conditions of the system might gradually
erode the capacity of the system. For instance, cities in most developing countries invade
agricultural areas and cause shifts. When the system changes from pre-flood to flood, the
A systematic approach to the dilemma between flood vulnerability and resilience - review and concepts
631
momentum of interactions between stress and resources is more pronounced (Figure 4). Flood
will add to the vulnerability, changing the system. In case the policy remains unchanged, the
components of the system will differ during pre-flood situations and the flood. If the system
exceeds its recovery threshold during the flood driven by external abrupt disturbances, internal
gradual changes, or both, a new regime will be the result [46]. Once moving into a new regime,
it is expensive returning to the previous one. An example is provided by the change from clear-
water to turbid lakes [52]. If the disturbances by the flood exceed the resources mentioned in
Figure 4, the system will move from state 2 (creative regime) to state 3 (resistant regime) (Figure
4). It is difficult to reverse the system to its original regime. Instead, if management provides
sufficient resources to solve the stress, the system possibly surpasses the threshold of the
resistant regime which results in a new creative regime (from state 3 to state 4 in Figure 4). This
does not only apply to flood risk management. If stakeholders use resources to unexpectedly
prevent system changes [39], their actions might increase the current levels of stress and push
the system towards the higher level of resistance (from state 3 to state 5 in Figure 4). For
example, the 2015 flood in York city (UK) the River Foss was hitting record heights as a result
of extreme precipitation. Once the Foss Barrier, York's major flood defense, was submerged, an
electricity cut prevents water discharge. Finally, the Foss Barrier was lifted and the water
submerged the entire the city.
It is equally important to consider the influences of upper and lower systems on the shifts
of the focal regimes [43,46,47]. For example, flood risk management at District level should
address the relations between the City and the County [13]. Changes of the system will be more
complex because decisions taken at different scales consider different types of resources and
stress [1]. This is known as the modifiable areal unit problem (MAUP) [53] in which the
aggregation from the focal scale to either larger or finer scales often fades out local details. MEA
[54] suggested scale-dependent, scale-independent and non-scalable variables to characterize
this problem. Examining the changes between non-flood and flood situations at different scales
is subject to further studies.
6. CONCLUSIONS
The proposed framework integrates major points of the flipping coin (vulnerability and
resilience are normalized as stress and resources, and they are two sides of the same coin) and
separation concepts (vulnerability and resilience both can generate positive and/or negative
outcomes) to address the dynamic interactions between ecological vulnerability and resilience
prior to and during floods. Ecological vulnerability involves a wide array of stress types
resulting from human-nature interactions. When these concepts are equivalent, it is easy to
explain the momentum of the system using the multi flipping-coin approach. The proposed
framework however relies on available data and the participation of the stakeholders.
Even when separating ecological vulnerability from resilience (which allows explaining
their dynamic interactions) the proposed framework has explicit limitations:
• The framework is limited in designing accurately the maximum stress and resources.
This has to do with the available data in the study areas. Data can assist quantifying the
depth and height of creative and resistant regimes.
• The specification of a regime is always temporal because environmental, social and
economic processes are dynamic and lead to changes in the state of the system.
• Stakeholders help deciding on stress and resources indicators and their state.
Hoang Cong Tri, Luc Hens, Pham Minh Thien Phuoc, Nguyen Thanh Hung, Tran Ha Phuong
632
• Conceptualizing ecological vulnerability will make the exercise complex, as it has to
deal with: (i) covering stress during and prior to the floods, and (ii) defining variables
and state of the environmental, social, and economic processes both prior and during the
flood.
• The framework does not focus on long term effects from prior to post-flood scenarios
because determining flooding periods is local specific. However, once the momentum
between pre-floods and the actual conditions of the system at risk is established, direct
causes and solutions for dealing with the flood are provided. The proposed framework is
also applicable for post-flood evaluations. As long as the pre-flood and flood conditions
are examined, post-flood can be properly handled. The 2005 flood in New Orleans (US)
provides an example.
• The focus should not be on urban areas alone. However, in developing countries,
urbanization and population growth affect agricultural land use quite dramatically. Low-
income citizens often attempt to settle in floodplains where drainage systems are, as a
rule, outdated. The theory addressed by this paper is applicable for both rural and urban
areas. Urban or rural resilience is “in se” not different.
• The framework does not provide solutions for cross-scale measurements.
Further studies should explore more knowledge to improve the framework. Additionally,
one should pay attention to selecting variables and cross-scale measurements. Selecting
appropriate sets of variables for ecological vulnerability and resilience assessment is a daunting
task as there is currently no standard. The issue has two major aspects: One is how many
variables are enough? And the other one is about which variables characterize best stress and
resources? This second aspect re-addresses the crucial role of the stakeholders in the evolution
of the system because some resources can amplify stress. Designing spatial units for cross-scale
measurements is equally important. Scaling the system up and down between different policy
levels requires advanced GIS and Remote Sensing techniques to address the MAUP.
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