RAF Resilience Assessment Framework—A Tool to Support Cities’ Action Planning

Abstract

Urban areas are dynamic, facing evolving hazards, having interacting strategic services and assets. Their management involves multiple stakeholders bringing additional complexity. Potential impacts of climate dynamics may aggravate current conditions and the appearance of new hazards. These challenges require an integrated and forward-looking approach to resilient and sustainable urban development, being essential to identify the real needs for its achievement. Several frameworks for assessing resilience have been developed in different fields. However, considering the focus on climate change and urban services, specific needs were identified, particularly in assessing strategic urban sectors and their interactions with others and with the wider urban system. A resilience assessment framework was developed directing and facilitating an objective-driven resilience diagnosis of urban cities and services. This supports the decision on selection of resilience measures and the development of strategies to enhance resilience, outlining a path to co-build resilience action plans, and to track resilience progress in the city or service over time. This paper presents the framework and the main results of its application to three cities having diverse contexts. It was demonstrated that the framework highlights where cities and urban services stand, regarding resilience to climate change, and identifies the most critical aspects to improve, including expected future impacts.

1. Introduction

Urban areas are complex, vulnerable and continuously evolving systems. In these dynamic areas, the existence of interacting strategic services and of interdependent services and assets, as well as the involvement of a multiplicity of stakeholders, adds complexity to their management. Besides, the significant impacts of climate dynamics (such as intense precipitation events, tidal effects, droughts or heat waves) in the urban strategic services, people, natural environment and economy, as well as the aggravation of current conditions and the emergence of new hazards, also need to be considered in their management [1,2].

As referred to in [3], following the World Economic Forum 2014, by 2050, exposure of city dwellers to various hazards, including earthquakes, tsunamis, urban floods, cyclones and storm surges, is expected to double. These challenges require an integrated and forward-looking approach to resilient and sustainable urban development, incorporating the interdependencies between systems as well as including stakeholders and citizens perceptions and needs. In order to achieve this, several long-term agendas have been adopted as parts of the United Nations Agenda 2030 for Sustainable Development, such as the Sendai Framework for Disaster Risk Reduction 2015–2030, the Sustainable Development Goals, the New Urban Agenda and the Paris Agreement [3]. A relevant consideration in all of these agendas is the incorporation of assessment steps for tracking their implementation [4].

The resilience concept has evolved over time and among disciplines [5,6]. Herein, urban resilience refers to the ability of human settlements to withstand, recover quickly and adapt from any plausible hazards. Resilience to disruptive events not only refers to reducing risks and damage from disasters, but also the ability to quickly bounce back to a stable state. Besides addressing disaster risk reduction, resilience includes changes in circumstances [7,8,9,10].

In order to identify the real needs for enhancing urban resilience, as well as the efficiency and effectiveness of planned or implemented measures, a resilience assessment is essential. Therefore, assessing the current and expected future status of resilience is a basis for cities to know where they are, helping to identify strengths and weaknesses, thus supporting the decision on strategies, actions and measures to be taken, planning for the long-, medium- and short-terms and assessing the progress.

Since the cities are dynamic systems with evolving hazards, it is essential to regularly carry out the assessment of their resilience, considering the principle of continuous improvement [11], and to have tools to support this. Several tools and frameworks for assessing resilience have been developed in different fields of study by a wide variety of stakeholders, such as those created by Local Governments for Sustainability (ICLEI) 2010, UN-Habitat City Resilience Profiling Tool (UN-Habitat CRPT) 2013, Rockefeller and Arup 2014, World Bank 2015, United Nations Office for Disaster Risk Reduction (UNDRR, former UNISDR) 2017, U.S. Environmental Protection Agency (EPA) 2017, among others [5,7,8,9,12,13,14,15,16]. Within the scope of the current work, i.e., climate change with a focus on water, relevant resilience assessment frameworks are presented in Table 1. It synthetizes the themes, urban sectors and metrics considered in each framework [5,7,13,16,17].

Table 1. Synthesis of resilience assessment frameworks for climate change.

Framework	Themes Addressed						Sectors Addressed							No. of Metrics	Reference
	Governance	Social	Spatial	Built environment	Economy	Natural Environment	Water	Wastewater	Stormwater	Waste	Energy	Mobility	Other(s) *
EPA conceptual framework	✓	✓	✓	✓	✓	✓	✓	✓	✓		✓	✓	✓	163	[15]
City Resilience Framework	✓	✓	✓										✓	156	[13]
UNDRR Disaster Resilience Scorecard for cities	✓	✓	✓	✓	✓		✓	✓		✓	✓	✓	✓	47 preliminaries 117 detailed	[8,9]
City Resilience Index to Sea Level Rise	✓	✓		✓	✓	✓	✓						✓	13	[18]
Climate Disaster Resilience Index	✓	✓		✓	✓	✓						✓	✓	120	[19]
Climate Disaster Resilience Index	✓	✓		✓	✓	✓						✓	✓	82	[20]
Climate Resilience Screening Index	✓	✓	✓	✓	✓	✓	✓	✓			✓	✓	✓	117	[16]
Flood Resilience Index	✓	✓		✓	✓	✓	✓	✓		✓	✓	✓	✓	91	[21]
Resilience Factor Index	✓	✓		✓	✓								✓	17	[22]
Community disaster resilience	✓	✓		✓	✓	✓							✓	26	[23]
NIST (National Institute of Standards and Technology) Community Resilience Assess. Methodology	✓	✓		✓	✓	✓	✓	✓			✓	✓	✓	-	[24]
UKWIR (UK Water Industry Research)						✓	✓	✓	✓					73	[25]
UN-Habitat CRPT	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	148	[7]

* e.g., Telecommunications, healthcare, education, population.

Taking into account the mentioned scope, the need of a framework (Table 1) that is freely available to be usable by cities and urban services managers was identified, allowing, on the one hand, a structured and objective-driven assessment of their city’s resilience considering the integration of all themes and sectors simultaneously and, on the other hand, an assessment of resilience of a single sector considering its interdependencies with other sectors and its contribution to the city resilience.

Grounded in the analysis of these existing frameworks, and in order to bridge the additional gaps and needs identified, particularly in the assessment of strategic urban sectors and their interactions with both other sectors and in the wider urban system, the Resilience Assessment Framework (RAF) was developed—a resilience assessment framework with focus on climate change and the water cycle, herein described.

2. Materials and Methods

2.1. RAF—Resilience Assessment Framework Aims, Assumptions and Development Approach

Considering the challenges of urban areas related to the potential effects of climate dynamics, enhancing urban resilience requires: (i) identification of the real needs, (ii) sustainable action planning and (iii) assessing progress. In order to support the mentioned requirements, bridging the gaps and the abovementioned needs identified, a Resilience Assessment Framework (RAF) was developed with the main purpose of contributing to the referred requirements, namely:

(i)

Directing and facilitating a structured resilience diagnosis of the cities and of the strategic urban sectors, following an objective-driven approach [11] with defined assessment criteria and identifying data gaps, opportunities, threats, strengths and weaknesses, highlighting the areas for improvement.

(ii)

Outlining a path for the development of cities’ resilience action plans by supporting decision-making in the selection of resilience measures and the development of strategies to enhance resilience.

(iii)

Monitoring the resilience progress of a city or service over time, by applying it periodically, and facilitating communication among stakeholders.

The RAF described herein considers the following assumptions:

• The scope is urban resilience to climate change (CC), with a focus on the water cycle, meaning that other diverse resilience drivers such as earthquakes, economic crises and cyberattacks, are not taken into account.
• The emphasis is on the city, services and infrastructure resilience, meaning that resilience aspects such as social and political are not developed for diagnosis, but they are incorporated whenever significant for city, services’ and infrastructures’ resilience.
• The services within the RAF scope are those comprised in the urban water cycle, water supply, wastewater and storm water and those having interconnections and interdependencies, closely related with the water services: waste management, electrical energy supply and mobility.
• The external context of the city and services is considered by a standard characterisation profile of the city and of the services, since it is fundamental to identify the main threats and to support the assessment, particularly the interpretation of results.
• The city and services multi-scale, multi-sectoral, multi-hazards and interdependencies are addressed, meaning that the RAF incorporates: different scales—city, services and infrastructure, the diverse sectors presented above, assessment of several hazards and of aspects related to interdependencies between different services and infrastructures.
• The continuous improvement principle [11] is followed and, since cities are dynamic, it addresses the progress of the strategies’ implementation and considers their effect, before, during and after an event and changes in circumstances.
• The long-, medium- and short-terms are incorporated considering three different and aligned assessment levels for the city, services and infrastructures (strategic—overlooking a long-term planning horizon and requiring the involvement of the entire organisation, addressing the overall city and considering its vision; tactical—overlooking a medium-term planning horizon and addressing departmental or sectoral activities in the city, services and infrastructure; and operational—referring to short-term horizon, addresses the actions to be taken in the effective implementation of measures in the city, services and infrastructure) while, as an integrated assessment, addresses the two first.
• A flexible structure is used, based on assessment metrics, allowing it to be expanded to other resilience drivers, dimensions or services.

The development and implementation of the assessment process, in collaboration with different stakeholders, promotes their empowerment and enhance their role in the decision-making process [26], as well as in the implementation of improvement solutions. To consider this, the RAF development was carried out in a stepwise process (Figure 1), comprising the analysis of existing assessment frameworks and related recommendations, and the definition of a preliminary proposal, which was validated to produce the final version.

Figure 1. Resilience Assessment Framework (RAF) development process flow chart.

The validation process included an external and an internal validation [26]. The external validation involved different stakeholders, representatives of research organisations, city departments and urban service utilities, allowing for incorporating their concerns as well as their own context and reality through collaborative workshops. Three workshops were implemented in each city, Barcelona (Spain), Lisbon (Portugal) and Bristol (UK), to obtain the stakeholders’ opinion on the RAF relevance, structure and applicability, as well as their concerns, own context and reality. Overall, 24 to 38 stakeholders attended each of the sessions, from 13 to 24 different organisations, answering individually and by sector to several surveys.

To ensure coherence, feasibility and effectiveness of the approach, the internal validation was carried out in the abovementioned cities, having different characteristics and contexts, which applied this framework involving the respective stakeholders. Each city and respective services provided their own data and answers to all applicable metrics. From the external and internal validation analysis, it was possible to identify the RAF components that benefited from additional improvements and those that less fitted the cities’ available information, thus supporting the development of the final framework herein presented. It is important to take into account that cities are multi-dimension entities and, therefore, urban resilience needs to consider multidisciplinary insights. Additionally, resilience of a city is determined by diverse interacting systems and their relationships. For this reason, resilience also depends on the overall performance, interactions and capacity of its systems in their everyday operation, not solely on its ability to cope with specific natural hazards or to adapt targeted areas to the impacts of climate change [27]. Thus, it is essential to address interdependencies and cascading effects [28]. Another relevant aspect is that it needs to include both sudden crises as well as interacting long-term stressors, address multiple hazards, characterise the specific geographic extent, consider physical dimensions, involve community members and be adaptable and scalable to different communities and changing circumstances [24]. These requirements were considered in the RAF development.

2.2. RAF—Resilience Assessment Framework Description

RAF sought alignment with international frameworks for resilience assessment, particularly with UNDRR Disaster Resilience Scorecard, both preliminary and detailed levels [6,7], and UN-Habitat, and made significant developments with regard to its scope and focus on urban services. The RAF considers the UN-Habitat resilience dimensions [29]: organisational (integrates top-down governance relations and urban population involvement, at the city level), spatial (referring to urban space and environment), functional (resilience of strategic services) and physical (resilience of services infrastructure). Time dimension is implicitly integrated as part of the analysis. The RAF (Table 2) has a hierarchical tree structure (Figure 2) meaning that, for each dimension, resilience objectives are defined, representing the ambitions to be achieved in the medium–long term by the city and services. For those dimensions related to the urban services, they firstly unfold into sub-dimensions, where each sub-dimension represents one service to be assessed. Each objective is described by a set of criteria that translate the different points of view associated with it. Each criterion assembles the respective assessment metrics, through which it is possible to classify the resilience development level by comparison with reference values. Metrics are then defined consisting in questions, parameters or functions used to assess the criteria. Some of the RAF metrics correspond to or were adapted from existing frameworks, mainly from UNDRR framework (former UNISDR)—found to be highly relevant for the scope of the RAF, and others were newly developed. In Appendix A, the complete structure is presented. As an example, Table 3 illustrates the metrics definition to assess, within the spatial dimension, the objective of spatial risk management from the perspective given by the criterion impacts of climate-related events, showing the hierarchical tree structure mentioned above.

Table 2. Overview of the RAF dimensions.

ORGANISATIONAL			SPATIAL
OBJECTIVE Criterion	No. total metrics	No. essential metrics	OBJECTIVE Criterion	No. total metrics	No. essential metrics
COLLECTIVE ENGAGEMENT AND AWARENESS			SPATIAL RISK MANAGEMENT
Citizens and communities’ engagement	5	3	General hazard and exposure mapping	5	5
Citizens and communities’ awareness and training	5	3	Hazard and exposure for CC	3	3
LEADERSHIP AND MANAGEMENT			Resilient urban development	7	4
Government decision-making and finance	4	3	Impacts of climate-related event	2	2
Coordination and communication with stakeholders	4	2	PROVISION OF PROTECTIVE INFRASTRUCTURES AND ECOSYSTEMS
Resilience engaged city	19	13	Protective infrastructures and ecosystems services	9	6
CITY PREPAREDNESS			Dependence and autonomy regarding other services considering CC	3	2
City preparedness for disaster response	13	8	TOTAL	29	22
City preparedness for CC	7	6
City preparedness for recovery and build back	7	5
Availability and access to basic services	10	7
TOTAL	74	50
FUNCTIONAL			PHYSICAL
OBJECTIVE Criterion	No. total metrics	No. essential metrics	OBJECTIVE Criterion	No. total metrics	No. essential metrics
SERVICE PLANNING AND RISK MANAGEMENT			SAFE INFRASTRUCTURE
Strategic planning	5	5	Infrastructure assets criticality and protection	5	5
Resilience engaged service	5–6	4–5	Infrastructure assets robustness	10–14	4–6
Risk management	7–12	2–7	AUTONOMOUS AND FLEXIBLE INFRASTRUCTURE
Reliable service	6–11	1–5	Infrastructure assets importance to and dependency on other services	3–4	3
Flexible service	4–6	1–4	Infrastructure assets autonomy	1–6	0–4
AUTONOMOUS SERVICE			Infrastructure assets redundancy	1–3	0–3
Service importance to the city	2	1	INFRASTRUCTURE PREPAREDNESS
Service inter-dependency with other services considering CC	2	0	Contribution to city resilience	3–4	2–3
SERVICE PREPAREDNESS			Infrastructure assets exposure to CC	3	0–3
Service preparedness for disaster response	0–4	0–4	Preparedness for CC	2	1
Service preparedness for CC	6–8	4	Preparedness for recovery and build back	7–9	2–4
Service preparedness for recovery and build back	0–15	0–8	TOTAL	35–50	17–32
TOTAL	37–71	18–43

Figure 2. RAF tree structure.

Table 3. Metrics definition—example for spatial dimension, objective spatial risk management, criterion impacts of climate-related event.

DIMENSION: SPATIAL objective: spatial risk management
Criterion: Impacts of Climate-Related Event		Unit
Metric: S16 Definition   Dimension Importance Metric type	Human loss in the last events Human impact of the last climate-related event, with similar or harsher climate variables than the most probable scenario Spatial Essential Open value	(-)
Please answer with an estimated figure [inhab.], disaggregating according to (a) number of casualties, (b) missing persons and (c) people affected—including severe injuries and displaced. This metric allows to answer with a value. Development level: assessment rule - (a) number of casualties - (b) missing persons - (c) people affected—including severe injuries and displaced		Develop. Level   3 if a, b and c = 0 2 if a and b = 0 and c ≤ 50 1 if a = 0, b ≤ 5 and c ≤ 50 0 if any other answer
Metric: S17 Definition   Dimension Importance Metric type	Damages in urban footprint in the last events Impact on urban footprint of the last climate-related event, with similar or harsher climate variables than the most probable scenario Spatial Essential Single choice	(%)
Consider urban footprint as a spatial extent of urbanised areas on a regional scale. Development level: assessment rule - 0% - Less or equal to 0.5% - Between 0.5% and 2.5% - More or equal to 2.5%		Develop. level   3 2 1 0

The framework considers past, existing and future conditions in the assessment. To incorporate the uncertainties associated to expected variations in climate-related variables, some metrics are specific to CC assessment scenarios, namely those that address preparedness for CC, and that anticipate the city and services’ exposure or vulnerability to future scenarios. Besides, the consideration of reference values allows to generally address uncertainties in the assessment.

A relevance degree is assigned to each metric, namely: essential, corresponding to all metrics with higher relevance, required to integrate the resilience assessment of any city or service, complementary, additional metrics to be considered whenever integration of city or service specific aspects is sought, corresponding to a more detailed resilience assessment and comprehensive, additional metrics recommended whenever a more in-depth assessment is aimed, for a city or service with higher maturity in its resilience path. Accordingly, depending on the resilience maturity, the city or service aiming to apply the RAF may select a given set of metrics, according to their relevance.

Additionally, every city or urban service needs to operate in its own specific political, economic, geographical, climatic and cultural context. Considering the context information is fundamental in interpreting any assessment. Following this, city and services’ characterisation profiles were developed to integrate the RAF framework, regarding its scope and focus. These profiles require information on geographical characteristics, climate, population, economy and governance, built environment and infrastructures, for the city. Regarding each service, it considers information on context characterisation, climate and infrastructure assets.

2.3. Research Sites

2.3.1. General

In order to test and validate the RAF to assess the cities’ resilience to climate change with a focus on the water cycle, it was applied to Bristol (UK), Barcelona (Spain) and Lisbon (Portugal) by the respective cities and strategic services managers. These three cities represent diverse context characteristics as well as different climate change-related concerns. The application was undertaken using the RAF App, a web-based application tool reproducing the RAF structure that allows selection of applicable dimensions and services to assess and allows private submission of answers to the metrics. The results may be visualised graphically (Figure 3, Figure 4 and Figure 5) and reports are also provided [30].

Figure 3. Bristol resilience assessment results for flooding: (a) Overall assessment, (b) overall assessment per dimension, (c) assessment of the objective autonomous electrical energy service, (d) assessment of the criterion water service preparedness for disaster response.

Figure 4. Barcelona resilience assessment results for flooding: (a) Overall assessment, (b) overall assessment per dimension, (c) functional overall assessment per service, (d) physical overall assessment per service infrastructure.

Figure 5. Lisbon resilience assessment results for flooding: (a) Overall assessment, (b) overall assessment per dimension, (c) physical overall assessment per service infrastructure, (d) assessment of the objective spatial risk management.

2.3.2. Bristol

Located in the south-west England, predominantly on a limestone area, Bristol is one of the most densely populated parts of the UK and, after London, the second largest city in the southern region. Most of the urban extent of Bristol is based around the watercourses and river network, with two major rivers flowing through the city (Avon and Frome rivers), resulting in a characteristically hilly landscape. It is one of the warmest cities in the UK and there is a relatively even distribution of rainfall throughout the year, although the autumn and winter seasons tend to be the wettest. Within this context, Bristol has been investing in plans to create and improve resilient systems to tackle its various urban challenges. Based on the analyses conducted by local and international actors working on resilience, the main urban challenges in Bristol can be profiled firstly in terms of natural and environmental hazards and secondly with regards to broader socio-economic issues. Bristol has suffered from significant flooding in the past, with the floating harbour and low-lying city centre being identified as key areas vulnerable to tidal, fluvial and groundwater flooding. The flood of 1968 was one of the most significant and damaging flooding events in the city, caused by both surface water and fluvial flooding that resulted in high damages and impacts to the city and its inhabitants. The construction of large interceptor tunnels in response to this, to divert exceedance flows higher up in the catchment, reduced fluvial flood risk in the city. In 2012, significant flooding occurred across most of the UK due to some of the highest rainfall events since record collection began. During this time, the most notable single flood event lasted two days, with 30 houses internally flooded and many more suffering flooding of gardens, garages and driveways. In order to better manage flood risks in Bristol area, a ‘Local Flood Risk Management Strategy’ was produced and released in early 2018. The Strategy sets out the Bristol City Council vision for managing flood risk in the city, together with other organisations that have a role in flood-risk management [29]. Bristol City Council has already developed an intensive work towards resilience, and it is proactively committed to increase Bristol’s resilience: from social cohesion to economic stresses and by enhancing resilience to all sources of flooding. The resilience of the city to climate change (CC) can be highly related to its urban services’ resilience, their interdependencies and cascade effects. For Bristol, the resilience assessment was undertaken for the flooding hazard related to rainfall and sea level variables, by its importance regarding Bristol resilience to CC.

2.3.3. Barcelona

Located on the northeast coast of the Iberian Peninsula facing the Mediterranean Sea, Barcelona is the capital city of the autonomous community of Catalonia, Spain. The city is situated on a plain spanning and is bordered by the mountain range of Collserola, the Llobregat river in the southwest and the Besòs river in the north. Barcelona is the second most populous municipality within Spain. However, the population increased slowly but steadily until the 1970’s, when the city reached its maximum population, thereafter, it stabilized and even decreased at the beginning of the 21st century, reaching the average population of 1.6 million inhabitants. Barcelona’s physical expansion has been limited by the mountains and the sea, resulting in a relatively high population density, among the highest in Europe. Within this context, Barcelona’s major vulnerabilities are mainly attributable to the natural and environmental threats faced by the wider Catalonia region. Barcelona’s past and recent history has been punctuated with recurrent water crises but also with rainfall events with very strong intensity over short time frames. The most severe and recent disruptive event hitting the urban area was between 2004 and 2008. During that period, four years of scarce precipitation in the Llobregat and Ter rivers’ headwaters, coupled with an increased evaporation rate due to high temperatures, culminated in the Spring 2008 water crisis affecting over 5.5 million people in the broader Catalonia. In that context, the Regional Government had to adopt exceptional procedures to minimise water waste, while the City of Barcelona was simultaneously forced to introduce restrictive measures over water use. Since then, several structural measures to ensure water supply have been implemented [29]. In January 2018, the city declared the pre-alert level of the Drought protocol after three consecutive years of low rainfall. The city is affected every year by an average of three intense rainfall events and one extreme flooding event every five years, although these frequencies have been increasing in the last years. Barcelona also has records of one heat wave every four years, a trend that has been increasing notably in the latest years. In 2003, a heatwave that lasted 13 days increased in more than 40% the average mortality. The last heat wave event was in summer 2018, it was 7 days long and caused up to 10 direct deaths. The resilience of the city to climate change can be highly related to its urban services’ resilience, their interdependencies and cascade effects. The Barcelona Municipality has already developed an intensive work towards resilience, and it is proactively committed to increase Barcelona’s resilience: from social exclusion to economic stresses, flooding, drought and heat waves. For Barcelona, the resilience assessment was carried-out for flooding, combined sewer overflows, drought and heat waves, considering the variables related to rainfall, sea level and temperature.

2.3.4. Lisbon

Located on the northern bank of the Tagus River’s estuary, one of the 18 municipalities of the biggest Portuguese metropolitan area, Lisbon is the capital of Portugal and the second largest European port on the Atlantic Ocean. The city has a Mediterranean Climate (Csa), characterised by dry and hot summers and wet and fresh winter periods with a relatively low precipitation rate compared to other Portuguese cities. Lisbon Metropolitan Area, with a population of 2.8 million inhabitants, stretches on both sides of the Tagus River, contributing to 37% of the national economic output. Today, Lisbon is a complex system with more than 1.0 million citizens who live, work, study, circulate and visit the city, Portuguese in the majority, with different ages, cultures, religions, ethnicities, education levels, knowledge and languages. Based on the analyses conducted by both local public stakeholders and international actors working on resilience in Lisbon, one of the urban challenges is related to a combination of contextual environmental, emergency, civil protection and urban planning threats with the contingent impacts of climate change crisis [29]. Since 1950, about 43 relevant events of extreme weather occurred in Lisbon. From these, nine events were related to hot weather, including heat waves, with a maximum temperature of 42 °C recorded in August of 2003, 13 events related to cold weather, including cold waves, with a minimum temperature of −1.2 °C recorded in February 1956, two strong wind and gusts events, with a maximum wind velocity of 108.4 km/h, recorded in January 2014 and 10 rainfall-induced flood events, with a maximum return period of 500 years, recorded in November 1983. The resilience of the city to climate change can be highly related to its urban services’ resilience, their interdependencies and cascade effects. Lisbon Municipality has already developed an intensive work towards resilience, and it is proactively committed to increase the resilience of the city: from social exclusion to economic stresses and from seismic shocks to flooding, combined with 17 Sustainable Development Goals’ achievement. For Lisbon, the resilience assessment was undertaken for the flooding hazard, related to rainfall and sea level variables.

3. Results

3.1. Bristol

The RAF was applied in Bristol in order to assess the current level of city resilience to flooding. Some results are presented in Figure 3. This could then subsequently identify where the gaps lie and what particular aspects are lacking to help formulate plans to improve or enhance upon the existing status, based on this resilience diagnosis. It went into a great level of detail investigating many aspects of city resilience quite thoroughly. The overall resilience development in the city was deemed as advanced in nearly half of the aspects assessed (Figure 3a). In this same respect, around a quarter were shown as progressing and the remainder incipient, unanswerable or not applicable. Various city services were given consideration including storm water, wastewater, energy, mobility and solid waste management operations.

The analysis highlighted the advancement in organisational areas more so over physical areas (Figure 3b), which were deemed more absent. Infrastructure resilience to climate change is therefore the main concern on reflection of this. In their own respect, the individual services seem resilient to a point, due to a focus on building resilience to historical events in the city and in response to national flood-risk issues. There is, however, susceptibility in the realms of reliance upon inter-related services and a lack of understanding of the cascading impacts and interdependencies between them.

The results from the analysis highlight the coordination between governmental organisations that is not always experienced to the same level externally with all privately run organisations. Engagement with communities is also a dynamic that is not completely to its maximum sufficiency. Availability of service resources is good, since diverse energy sources are used in the city, but the reliance on electricity without alternative provisions is a notable limitation (Figure 3c). Resilience standards to adhere to as well as the position of a Chief Resilience Officer being eliminated make for more areas lacking in Bristol. Learning from past events is a commendable action performed well in Bristol, but the running of emergency scenarios and drills does not appear to be simulated enough to gain its full benefit (Figure 3d). The known threats of a significant proportion from sea level rise and increased rainfall present an extreme level of vulnerability to the city and its inhabitants. There are, however, also opportunities presented, though through the declaration of a climate emergency in Bristol, they require drastic action implemented via a climate strategy. The chance for properly applying climate adaptation measures utilising the knowledge developed of high-risk areas in the city therefore has greater prospect for recognition and the enablement for realisation.

3.2. Barcelona

The RAF enables to highlight where Barcelona and its urban services stand today regarding resilience to climate change, and to identify the most critical aspects to be improved, taking into account both the reference situation and the expected impacts of future climate change scenarios. The diagnosis allowed for understanding those aspects that are being tackled properly from the city and was also to determine gaps and areas of improvement thanks to the great level of detail of the different dimensions that make up the assessment. Some results are presented in Figure 4. The exhaustive analysis led the city to an intense and deep level of self-knowledge about its level of resilience in different ways of approach (Figure 4a). In this sense, the organisational and spatial dimensions yielded good results about the level of response to the metrics considered, reaching a response level of almost 100% (Figure 4b). Regarding the physical and functional dimensions, several services of the city were assessed, namely water, wastewater, storm water, energy, waste management and mobility. The assessment showed those services that are well managed and monitored as waste or water services, but it also highlighted the need of improvement in the energy sector, storm and wastewater and mobility services (Figure 4c,d). For Barcelona, most data gaps can be blamed on the definition of the metrics to be applied and the differences in the way how these metrics are calculated. Most of the time, the indicators did not fit with the ones the city already determines and it would entail a noteworthy effort to address the asked specifications. Without assuming harm, this identification of gaps means an opportunity to improve a new approach to measuring the different aspects of resilience in the city.

The RAF enabled the ability to be realistic with the resilience level of city services. It shed light on the state-of-the-art of urban resilience in Barcelona, highlighting those areas where the city works properly and progresses positively to a high degree of preparedness. At the same time, it has helped to determine those aspects where there is still room for improvement and has also given the chance of applying a methodology capable to reach the deepest areas that make up the operation of a city.

3.3. Lisbon

The RAF was applied in Lisbon in order to assess the current level of city resilience to flooding. The application of a structured resilience assessment framework enables the identification of the resilience criteria, objectives, services and city dimensions with major accomplishments, setbacks or opportunities for improvement. Therefore, it supports identification of resilience measures and development of strategies. Some results are presented in Figure 5. The overall resilience development in the city is advanced in nearly one third of the aspects (Figure 5a). Globally, around a quarter shows progress, meaning that significant steps were already taken, and the city and services are still developing specific aspects. The remainder correspond to incipient, unanswerable or not applicable metrics. Various city services were assessed with more detail, including stormwater, wastewater, energy, mobility and solid waste management.

The analysis highlighted a significant advancement in spatial areas more so over physical areas, which were deemed more absent (Figure 5b). The organisational dimension as well as all the services and infrastructures present aspects already having an advanced development level, while still having significant opportunities for improvement. In the mobility service, considering the significant percentage of metrics that were not answered, data may be not be easily applicable to the metrics provided or some lack of information may exist. This is also applicable to the infrastructure assessment of the stormwater, waste and energy services (Figure 5c). Infrastructure resilience to climate change is therefore the main concern on reflection of this. For all services, the contribution of infrastructure to city resilience needs to be more exploited.

The results from the organisational analysis highlight that citizens and communities’ awareness and training is one of the aspects that needs further development, followed by the city preparedness for disaster response and for recovery and build back. Engagement with communities is also a dynamic that is not completely to its maximum sufficiency as well as the coordination of financial plans and budgets for resilience.

Concerning the spatial analysis, the provision of protective infrastructures and ecosystems is well developed, while the knowledge on climate change hazard and exposure as well as impacts are highlighted as opportunities to be further developed (Figure 5d).

Generally, there is strong development of strategic planning and there is limited preparedness in the wastewater service for climate change, as well as limited autonomy for the majority of the services, with the exception of the stormwater service. There are, however, some susceptibilities in the realms of reliance upon inter-related services and a lack of understanding of the cascading impacts and interdependencies between those for climate change.

This diagnosis of the main strengths and weaknesses supports the identification of the adequate measures for resilience enhancement to climate change. This assessment is a step up in Lisbon’s Climate Change Resilience Process and one diagnosis to be integrated in the ongoing Climate Action Plan of the city.

4. Discussion

By applying the RAF (Section 2.1 and Section 2.2) to Bristol, Barcelona and Lisbon (Section 2.3), from the results obtained (Section 3.1, Section 3.2 and Section 3.3), it was possible to validate that it provides information on the assessment of the current level of the cities’ resilience to climate change with a focus on the water cycle. The framework delivers a structured assessment clearly identifying the work already carried out, translating the strengths of the cities’ resilience and which dimensions of resilience they fit into most. This is illustrated by the advanced or progressing values in Figure 3a,b, Figure 4a,b and Figure 5a,b. Besides the assessment of the organisational and spatial dimensions of the city, one particular aspect to emphasize is the identification of the contribution of the urban services to cities’ resilience, as evident in Figure 3b, Figure 4b–d and Figure 5b,c. At the same time, the framework highlights the gaps, including limitations on data related to unanswered metrics. It also indicates particular aspects that are lacking, as can be seen by incipient values in Figure 3c,d and Figure 5d, as well as those in more need of further development, given by progressing values in the same figures.

It is evident that the RAF enables to highlight where the cities and respective urban services stand today regarding resilience to climate change, and to identify the most critical aspects to be improved. It should, however, be noted that results of unanswered metrics, corresponding to limitations on data, may be due both to a lack of information or to the alignment in the way existing information is processed in the city with the way the metrics are calculated, as in the Barcelona case (Section 3.2). This last case is likely to occur in cities already using other assessment frameworks. Whenever the framework in use allows to assess the same concerns, i.e., the resilience objectives and criteria corresponding to those of the RAF, they may be used instead. Nevertheless, this provides the challenge to align the RAF with other existing frameworks in this scope. In these circumstances, it is fundamental to clearly identify actual data gaps in the cities and services that need to be filled.

Considering the assignment of a relevance degree described in Section 2.2, it is possible to undertake a stepwise process going into a gradually deeper assessment, depending on the resilience maturity of a city, allowing replicability of the methodology to other cities and services. The framework allows to go into a considerable level of detail investigating many aspects of city resilience quite thoroughly. The whole assessment provides a resilience diagnosis that helps with formulating plans to improve or enhance upon the existing status.

It is feasible to use the RAF to assess diverse hazards such as flooding, combined sewer overflows, drought and heat waves, as it was in the case of Barcelona (Section 2.3.2). The framework may be applicable to provide an overall response regarding the cities’ resilience assessment or it may be applied to assess a certain urban service within its scope (Section 2.1).

5. Conclusions

The resilience assessment framework (RAF) herein presented enables to highlight where the cities and respective urban services stand today regarding resilience to climate change, and to identify the most critical aspects to be improved, taking into account both the reference situation and the expected impacts of future climate change scenarios. The diagnosis allows for understanding those aspects that are being tackled properly and also to determine gaps and areas of improvement thanks to the great level of detail of the different dimensions that make up the assessment. It also provides a means to assess resilience progress, therefore contributing to an integrated and forward-looking approach to resilient and sustainable urban development. Additionally, it may facilitate communication among different stakeholders and between different decision levels.

The application of this framework to Bristol, Barcelona and Lisbon cities have demonstrated that the RAF is a tool that provides support to a structured assessment of urban resilience to climate change with a focus on water. Even though it was developed within the scope of climate change and with a focus on the water cycle, replication to other hazards and services is considered on its foundation. Given its different assessment levels, it may be used by any city, service or organisation that intends to undertake a resilience assessment with this scope and focus, regardless of their resilience maturity. The RAF allows to align with the resilience path and integrate the work already in place in the cities and services, as well as to consider the information provided by diverse analysis approaches and tools, already in use or to be used by the city and service managers. Given the adopted structure, an effective and robust implementation requires the involvement of multiple parties, in a collaborative process allowing incorporation of the best available information.

The RAF is a flexible framework allowing further inclusion of additional dimensions, such as social or economic, and of other objectives, criteria and metrics, for the services already addressed. Moreover, it may be strengthened with the incorporation of other services, such as telecommunication, education or health. Other development opportunities are the consideration of other hazards, such as earthquakes, or of other risks.