Methods and Tools Supporting Urban Resilience Planning: Experiences from Cork, Ireland

To prevent flood disasters, policymakers call for resilient cities which are better able to cope with flood hazards. However, actual adoption of resilience measures in urban planning is still limited, partly because it is not sufficiently clear how and to what extent resilience should and can be enhanced. To develop resilience strategies, information on the current resilience and on the effects of measures should be available. Since cities are complex systems, an assessment of resilience requires the input of different actors. To obtain and combine this input, a comprehensive approach which brings together many actors is required. Furthermore, resilience must be integrated in planning frameworks in order to enhance adoption by city policy makers. Tools which support and structure the contribution of different disciplines and actors will help to obtain information on the current resilience and to develop a shared vision on measures to enhance urban resilience. We illustrate our view with an example on Cork, Ireland.


Introduction
The world's policymakers, authorities, development organizations and donors emphasize the need for more resilient cities [1] in order to prevent hazards from resulting in disasters. The Sendai Framework for Disaster Risk Reduction 2015-2030 calls for more attention for resilience [2], as do the New Urban Agenda [3] and the Sustainable Development Goals [4]. Resilience also constitutes the paradigm of the 100 Resilient Cities campaign by the Rockfeller foundation [5]. These global policies, however, do not provide practical guidance for assessing and enhancing flood resilience within urban systems.
There is an on-going debate within the scientific community on the description and definition of resilience [6] [7] [8] [9]. Although the precise definition of resilience may not be agreed upon, there is nevertheless agreement on the notion of resilience and the most important system characteristics to enhance cities' or deltas' resilience to be better able to cope with hazards, such as extreme weather events and floods [10]. Recently, attempts have been made to derive principles based on those shared insights which may help policy makers define measures that enhance resilience. [11] proposed ten "essentials" for making cities resilient including conducting risk assessments, ensuring stakeholder participation, protecting critical infrastructure (abbreviated further as "CI") and assigning budgets. [12] developed a city resilience index. [13] provided guidance on how to build urban resilience to natural hazards. They claim that cities should protect their citizens and that public funding of resilience is therefore justified. They promote the sharing of risk information with actors to increase resilience and mention a number of critical steps such as: taking into account future uncertainties, looking at various aspects of the disaster chain and focusing on critical infrastructure. [14] defined lessons learned from hurricane Sandy and also mentioned sharing of information, anticipating on uncertain futures and aligning various policies and programs. [10] proposed five resilience principles for policy makers and consultants to guide enhancing resilience to natural hazards.
Although such principles and essentials help to make resilience more concrete, resilience needs to be included in commonly used policy frameworks to promote implementation of resilience measures. Information on current levels of resilience must be made available to enable informed decisions on the usefulness of resilience enhancing measures. Cities are highly complex and dynamic systems; their current and future resilience to a certain hazard will depend on many actors, processes and measures. Hence it is very difficult to quantify resilience and to assess the effect of measures on resilience, especially by local authorities themselves. Therefore, we propose to adopt approaches and tools which enable input of a wide range of actors from different fields, structure their discussion and contribute to the development of a shared vision on the cities' resilience and ways to enhance it.
This paper clarifies what we mean by resilience and then links resilience to policy frameworks to identify what information is needed to support policy makers in their search for resilience enhancing measures. Next we discuss the type of approaches and tools which may help obtain such information and illustrate this by an example of planning of urban resilience against floods in Cork, Ireland. We explain that resilience planning benefits from methods and tools which support the structuring and integration of information of different discip-

Theory: Urban Resilience to Floods
Resilience as a concept covers significant elements missing in "traditional" management of flood risks. Traditionally, flood risk management approaches focus on risks which are understood as a combination of flood probabilities and flood consequences [15]. Flood risk is often expressed in terms of the expected annual damage or expected annual number of casualties [15] [16]. Policy makers evaluate these risks by comparing these with acceptable risk levels or in an economic assessment. Reducing risks requires taking measures that reduce either the probability of an event happening or its consequences. An economic cost-benefit analysis will provide insight into the efficiency of proposed measures.
Such commonly applied risk analyses have some drawbacks: they neglect risk aversion in society and pay little attention to rare, but catastrophic events [17] [18]. These analyses often focus on direct tangible impacts and do not consider recovery, indirect effects and intangible impacts [18] [19]. Additional criteria are thus needed to assess measures.
The call for enhancing resilience usually includes a call for more attention to rare, but catastrophic beyond-design events, to intangible impacts, indirect effects and to recovery capacity of the society threatened by disturbances.
Resilience is generally considered a positive system characteristic that is related to the system's ability to cope with disturbances [20]. In policy documents resilience is generally defined at a large scale and not hazard specific. It needs, however, to be specified and operationalized in order to address it [21] [22] [23].
Both the system and the relevant disturbance should be clearly specified in order to define, implement and monitor resilience measures: "resilience of what to what?" [24].
In this paper, we define urban flood resilience as the ability of a city to cope with high rainfall intensities, river water levels and coastal storm surges either by being able to withstand those disturbances, or by recovering easily from the impacts they cause.
In evaluating resilience strategies, we consider how the set of measures building the strategy perform under different future scenarios of the urban area. To assess resilience, first the system boundaries and specific flood hazard must be defined and then relevant indicators to measure flood impacts and flood recovery time must be selected.
To support policymakers to deal with flood resilience, [10] translated the notions related to resilience into five guiding principles, namely: 1) Adopt a system's approach: To tailor flood risk management strategies to the socio-economic system, a comprehensive systems understanding is needed, including the interdependencies between subareas and the link between flood risks, recovery, economic activities and social networks [25]; 2) Look at beyond-design events: The risk perception of events with a low K. M. de Bruijn et al. Journal of Geoscience and Environment Protection probability but high consequences is often different from the "objective" risk as provided by economic analysis [17]. Rare but catastrophic events may call for measures which are not cost-effective in view of a standard cost-benefit analysis; 3) Develop infrastructure according to "remain functioning" principle: Design systems in such a way that consequences of failure are not catastrophic, but manageable; 4) Increase recovery capacity by looking at social and financial capital [26].
Measures which increase people's ability to recover include amongst others measures aiming at improving education level and well-fare but also measures which improve access to recovery funds e.g. insurances, relief grants, reconstruction employment schemes and so on; 5) Consider future changes in order to remain resilient into the future: Systems' resilience changes due to climate change, urbanisation, economic changes and economic growth. To remain resilient in the future, urban areas and urban policies need to be flexible, and urban planners need to learn and adapt to cope with gradual but uncertain changes.
These principles help policy makers to adopt a resilience approach, but they need to be translated to urban planning and tools and methods to support adoption will help further uptake.

Flood Resilience in Relation to Urban Planning
Cities are complex systems with many interrelations. The functioning of urban areas and the well-being of people in flood-prone cities may be threatened by floods. However, flood threats are just one of the many challenges which urban areas need to cope with. Others are for example urbanization, aging infrastructure, access to (sustainable) energy and social issues. To increase urban flood resilience, the other developments and challenges need to be considered, and strategies need to be understood in view of changes. As an example we mention the city Chennai in India where severe floods occurred in 2015. When addressing these floods, it is crucial to also address other major issues such as the aging and insufficient capacity of sewer and garbage management systems and to take into account the very high grow rate of the city [27].
Increasing resilience and developing sustainable pathways into the future, requires interaction between actors, and authorities and integration of knowledge on flood risks with information on urban activities, developments and assets [28]. Through mutual learning a shared vision can be developed on current levels of flood resilience and on potentially feasible measures to maintain and enhance resilience in the future.
Common policy frameworks for urban planning follow steps such as problem exploration, risk analysis, risk evaluation, and defining strategies [29]. We propose an urban resilience planning framework, which reflects the policy cycle (see Figure 1). It consists of four steps that are to be followed in an iterative way.
Reaching agreement on problem assessment and policy objectives is the key to

Scoping of Urban Flood Resilience
Resilience planning processes start with an inception phase in which scope and objectives of the planning process are defined: the hazards addressed and objectives pursued. Starting-points for the next steps are defined in the planning cycle. This includes specifying the dimensions of resilience together with related indicators. Choices have to be made to describe the system and its boundaries: what aspects and relationships are considered in the analysis of urban flood resilience.
Scenarios (i.e. plausible future situations) need to be defined that account for various uncertainties, including the possible impacts of climate change. Scenarios play a central role in defining adaptive strategies and help to define and prioritize low regret measures. Furthermore, "beyond design events" need to be identified to enable the assessment of flood resilience. Relevant actors need to be identified through an actor analysis.

Resilience Assessment
The level of resilience will be analyzed by calculating various indicators reflect- can be compiled of hazards, impacts and risks in the project area, which serves as input to the evaluation and management of flood resilience. Some of the resilience indicators may be quantified using computer simulation models; for other indicators a qualitative assessment may suffice.

Evaluation of Resilience
The next step after establishing the degree of resilience of the current system is the resilience evaluation. Evaluating resilience is essentially a societal and policy process which should answer the question: "How resilient is resilient enough?"

Enhancing Resilience
Strategies to enhance resilience should include a well-balanced mix of structural and non-structural measures, including measures which can be implemented in the short term. The strategies will be assessed on economic feasibility, social and cultural aspects, and environmental considerations under a wide range of future scenarios. The development of strategies in an interactive setting may be supported with decision support systems. Implementation of strategies will look into the financing of measures, as well as on-going long-term operation and maintenance costs. Governance arrangements should create the conditions for effective enforcement of regulations and public awareness campaigns.

Type of Tools and Methods Needed
In order to identify, analyze and evaluate measures which enhance resilience of cities we need methods and tools which produce information on system behavior, on the impacts and recovery rates of disturbances and on the effects of potential measures. Such an overview is not easily obtained as it requires information from multiple actors and disciplines. The literature suggests that approaches  [30]. In order to engage actors and obtain an overview of the whole urban system in relation to flood risks, interviews and workshops with experts and actors are needed. Such workshops may also enhance capabilities of actors and create ownership of resilience objectives, approaches and the way forward. They can help actors to relate their knowledge and responsibilities to the functioning of the system as a whole. They may also contribute to a shared vision on what measures or strategies are best and what actions should be taken by the individual actors. Methods and tools that structure and enhance discussions during workshops are crucial to reach this common view. Such workshops are beneficial for all four phases in the proposed urban resilience planning framework.
There is a wide variety of methods with different levels of participation available to engage actors [31]. Different methods include focus groups [32] and the Delphi method [33]. Two recently developed methods/tools, the CIrcle Tool and the Storyline Method, aim to better engage actors in the planning process. The storyline method helps to sketch the chain of events and actions, before, during and after a flooding which shows links between actions and actors [34], while the CIrcle tool structures and visualizes information on CI vulnerability [35]. Both aim to contribute to the development of a shared vision on the current levels of resilience and on potential measures to increase flood resilience of the city as a whole. The methods use existing information on flood risks, and involve many different disciplines and actors. This section discusses these methods and the case study on Cork will illustrate how they help to assess the current resilience and the impacts of potential resilience measures.

Storyline Method
The storyline method comprises selecting and analyzing specific scenarios together with relevant actors to identify the sequence of events, the responses of actors and the interactions between the actors. The storyline considers the sub events just before, during and just after the flooding. This approach does not replace, but complements common risk analyses. The way in which actors relate flood risk maps (which often contain aggregated information from many potential flood events) to their own actions and designs is not always clear. A storyline which corresponds to an extreme but realistic event, helps communication and clearly delineates actions between actors. The storyline method is thus principally designed to facilitate communication, information exchange and discussions in workshops. It has been applied in the Netherlands, to develop and analyze flood risk management strategies for the Island of Dordrecht [34].
The storyline approach comprises four steps which match with the resilience framework. In the scoping phase of the resilience framework, the first two steps are considered: 1) Initial phase: Describe the area, the flood hazards, the CI and relevant ac- The application of the storyline approach in workshops brings together actors from diverse disciplines and institutes, such as flood modelers, crisis managers, emergency services, spatial planners, and critical infrastructure managers. The approach is applicable also when data is not available. It results in a shared view on what may happen and on how different responses or situations interact. It also reveals data needs and contributes to strategy and measure identification [34].

CIrcle
Since one of the conditions for a resilient city is having resilient CI, we also discuss the CIrcle approach and tool as an example which supports urban planners in their resilience planning process. This tool is used to engage actors from dif- Secondly, all identified CI networks are presented as blocks in a circle diagram on the CIrcle tool (see Figure 2) and for each CI network the resistance and resilience to flooding is discussed. The network components' resistance is the water depth which the element can withstand without any damage and its resilience is related to the damage severity and recovery rate. If, for example, a power supply operator brings forward that failure in power supply will occur if water depths exceed 25 cm at the network control cabinets, then in the outer circle of the diagram one block is assigned to power supply and the threshold of 25cm is then added.
Thirdly, for each vulnerable CI network type it is discussed if failure in service could trigger other CI networks to fail. If a failure in the power supply occurs, will, for example, the emergency managers be able to continue their work and if so, for how many hours? This information is then added as causal links between the blocks in the outer circle (see Figure 2). Generally, more information on the links is obtained from the group discussions than from discussions with individual actors. Finally, the effect of the disruption of CI on society is addressed and added to the CIrcle tool (number of people affected, costs, etc.).

Illustrative Example: Urban Flood Resilience of CI in Cork, Ireland
We illustrate the urban resilience planning framework and the methods and tools through their application in Cork. In the case study, we started with scoping the resilience issue: delineated the system and specified the hazard towards which resilience is needed. Then we did an actor analysis and proposed case specific resilience indicators. Then we assessed the resilience, evaluated it and considered measures to enhance the system's resilience. Council, and CI operators and managers to jointly elaborate the storyline. The CIrcle tool was used to support the workshop and to collect, visualize and present the information in a structured and coherent manner. After the workshop, the outcomes were combined into a description, graphs and maps.
In the evaluation phase a second workshop was held in which the outcomes of the first workshop were shared and discussed (September 2016). This workshop also focused on identifying further measures and thus also covered the enhancing resilience phase. The questionnaires, interviews, workshop report and case study report were kept confidential to promote engagement between actors.
To assess flood resilience of Cork City Centre we used two indicators, one for impacts: the monetary impacts related to a once in 1000 years flood and one for recovery: the number of affected person days which is equal to the product of the number of persons affected and the duration they are affected. We focused on the once in 1000 year scenario, which is a beyond-design event. The resilience indicators and findings are discussed in the next sections.

Scoping Phase
Cork City is the largest urban settlement within the Southwest Region of Ireland.
Cork City was originally built at the mouth of the River Lee, on an island in a marsh and is thus susceptible to flooding. The flows in the River Lee are influenced by two hydro-electric dams owned by Electricity Supply Board (ESB).
Cork City is at risk of tidal flooding during extremely high tides, by flooding from river discharges, and combined tidal and pluvial flooding. Fluvial floods are most damaging. The city has 120,000 inhabitants, comprises a large concentration of commercial and industrial activities, nationally important CI, and attracts a large commuter population from the surrounding hinterlands.
Flood management is carried out by the OPW at national level, the County and City Councils at regional and local level. Since the ESB manages the reservoirs which may attenuate flood waves, they influence flood risks significantly. The CI in Cork includes transport networks, utility services and furthermore there are vulnerable and crucial assets such as emergency services, hospitals and the university. In the management and operation of CI several actors are involved, including CI operators and managers (road, rail, air, port, water, energy), local authorities and first responders. A full description can be found in [38].
In 2009 a severe river flooding occurred which resulted in severe damage and interruption of critical infrastructure services: The main transportation routes were cut off, the roads to and from the hospital became inaccessible, the drinking water supply of about 87,000 persons was interrupted for about two weeks and the university suffered from large damage.
Since the flood event of 2009 damaged the CI severely, the study on the flood resilience of Cork focused on CI. We focus in this paper on the resilience of Cork City CI to fluvial flooding.

The Resulting Storyline
Based on the knowledge from the scoping phase we selected a once in 1000-year river flooding for the storyline. This is a beyond-design event which is a little more extreme than the 2009 flooding which was estimated as between a 100 and 1000 year return period. The three storyline phases (before, during and after the flooding) are briefly described below. A full description is found in [37]. The key CI owners are represented in this body also.
CI is now affected seriously. In this hypothetical scenario the roads along and across the river have become flooded and thus inaccessible. These include national primary roads. Cork City Council closes part of these roads and diverts traffic away from the city centre. There is a cessation of bus services and also the movement of emergency services is significantly restricted as the flooding of city centre roads increases. Small boats are deployed in some areas of the city to rescue trapped residents from their homes and to transport medical personnel to work in the city centre hospital. In future additional measures are planned by the OPW: hydraulic models will be made to further enhance the capacity of the reservoir operators and Cork City Council to forecast water levels and to operate the reservoir. Flood storage areas will be planned between the reservoirs and Cork City to prevent flooding of vulnerable urban areas. These actions increase resilience. The final resilience level depends, however, also on the degree of climate change and urbanization and spatial planning of the City and County Councils.

Evaluation Phase
To evaluate whether Cork is sufficiently resilient, the acceptable resilience level The measures which were already taken thus increased resilience significantly.
They focused on flood prevention (strengthening of quays, protecting the university grounds), emergency management, and impact reduction by protecting the drinking water production and power supply assets, which caused the largest impacts in 2009. Even if beyond-design events occur and the city is flooded, the power supply is likely to remain intact, and the more efficient emergency management would limit impacts and enhance recovery. Resilience thus has increased very much thanks to the implemented measures.

Further Enhancing Resilience Phase
In future, resilience may be further enhanced if e.g. flood storage areas are as-

Discussion
Global working"). The approach followed here which includes cascading effects and brings together different actors is not common yet.
However, the success of the approach will depend strongly on the active involvement of the right actors and an adequate support of the joint fact finding process, including a proper preparation of workshops. Since in Cork, the willingness to improve flood resilience is large and we discussed the workshops intention in interviews, we were able to get the right attendants present. In practice, it's not feasible to study all resilience dimensions in detail. Therefore we promote a phased approach: starting from a rather coarse comprehensive analysis to identify the dimensions and elements which are most relevant for the city's resilience and then a more detailed approach where needed. In the rather broad approach interaction with actors is crucial. Approaches which structure discussions amongst actors from various organizations and disciplines are needed next to the more common detailed mono-disciplinary risk analyses.

Conclusion
We conclude that the adoption of resilience in existing city planning frameworks is a prerequisite for implementation of measures to enhance resilience. Practical tools and approaches which help decision makers to obtain and structure information and to communicate with non-flood risk experts may provide valuable contributions to this process. Resilience is a broad concept that requires a comprehensive systems approach, which may be difficult to achieve with common