Impact assessment & cascading effects

Use these guidelines to:

Assess the impacts and cascading effects in critical services and infrastructures in cities from climate driven hazards.

Urban floods, combined sewer overflows, sea level
rise and droughts are among the major climate-related hazards that threaten our cities. These hazards can pose significant threats to the infrastructures and services. The failure of services due to climate driven hazards may trigger further impacts and disruptions to other services, known as cascading effects.

Within RESCCUE, the potential impacts on critical infrastructures and services as a result of climate driven hazards were selected to be assessed in the cities of Barcelona, Bristol and Lisbon for both current and future climate scenarios. Modelling and analysing results of such scenarios improved the understanding of the effect these may have on the respective cities, where the experience of operators may not be enough to foresee the potential response of the interdependent services outside of normal operating conditions.

5 steps to your solution:

What is your concern?
What benefits should you achieve?
What do you need to know?
What can you use?
What should you do?

What is your concern?

What hazards could impact your services?


What can they impact?

People safety
People bathing
Damage to
properties, goods and infrastructures
Electrical power supply
Water supply
Urban drainage

How can these impacts be assessed?

Integrated flood and traffic models
Water resource modelling
Integrated flood and electrical power distribution models
Drought and water supply models
Integrated flood and waste models
Integrated urban drainage and receiving water quality models

The results from impact assessment can be presented in form of risk and impact heatmaps and/or impact/disruption indicators with different levels ranging from low to high. Quantifying impacts is fundamental for understanding urban resilience with respect to climate driven events, identifying where the weaknesses lie within the chain of services and infrastructure in the city and how to improve the resilience through the incorporation of adaptation measures.

What benefits would you achieve?

Detailed impact assessment scenarios

Urban scale and regional scale scenarios for assessing impacts upon urban services and infrastructures and services as a result of climate driven hazards.

Adapted to your local needs

Generic impact assessment models designed to utilise models, GIS tools and data at varying levels of detail that allow for a wide range of cities and local authorities to carry out their analyses.

With high quality

Impact assessment models provide the means to analyse the potential risks and impacts that climate driven hazards may have in your regions. Models developed within both commercial and open source software and designed to work with a variety of data sources and differing scales depending upon city’s needs and resources.

Example of information used to assess potential impacts of flooding on properties

RESCCUE solves your problems
This is how!

What are your concerns?

What scale are your impact assessments?
Metropolitan Area
Localised regions

How do climate driven hazards impact services within your city?
It impacts a single urban service
The impacts result in cascade effects onto other urban services and infrastructures

When does the hazard event occur?
It is a current problem
It is a potential future problem

How long are services disrupted?
Short recovery time (hours)
Recovery takes several days
Longer-term implications (months, years)

What are the interdependencies between services?
Donor and Receiver relationships
Redundancies in place

High-quality, understandable, useful, usable, valid and reliable information is fundamental for a quality outcome.

What can you use?

Background information
Physical data for the model setup
(from drainage, electrical, water resources network, etc.).
Hazard Maps
(Current and Future Climate Change Scenarios).
Infrastructure fragility or property vulnerability information
(asset category, damage curves, etc.).
Local expert opinions.
Historical data for reference and calibration.

GIS based models.
Commercial or/and Open Sourc modelling tools.
Integrated model (loosely coupled models).
Outputs from hazard models are utilised with service/infrastructure data within impact assessment models/tools to simulate and quantify the potential impacts and disruptions to infrastructures and services that result from a given hazard.

Cascading Effects
The functionality of various critical services within the respective cities may be dependent upon the functionality of other critical infrastructures and services within the city whereby the failure within one sector may result in the failure in another.

Impact assessment maps and indicators
The derived impact assessment maps and indicators provides valuable insight into the potential losses and disruption hazards may cause and the cities resilience against such hazards. Interrogation of such data provides means to investigate what changes can be made to your city to reduce the impacts through Cost-Benefit Analyses.

What should you do?

Select climate driven hazards

Identify the main hazard and consequent cascade hazards of interest.

Define hazard-vulnerability relationships

Define how infrastructures and services respond to the selected hazard and how the responses vary with respect to magnitude of the hazard.

Validate impact assessments

Validate the obtained results against historical references such as insurance claim data and the data provided by risk owner and local stakeholders.

Select key/critical service sectors for impact assessment

Obtain data/information about critical services and infrastructures within your city.

Model selection

Select or build models for the analysis of impacts to services within your city or region.

What can you use to know that?

Comparative example of spatial distribution
of direct damages (without property value capping) as a result of Fluvial + Tidal flood event for a 1 in 200 year current scenario Vs 1 in 20 year future climate change scenario (with no adaptation strategies) to highlight potential consequences climate change and sea-level rise may have on a region.

Strategic urban services modelling experts:

Several RESCCUE partners worked together under the guidance of the University of Exeter to assess impacts to services and infrastructures from multiple climate related hazards for Barcelona, Lisbon and Bristol:

– University of Exeter
– Aquatec-SUEZ Advanced Solutions
– FIC (Climate Research Foundation)
– Cetaqua (Water Technology Centre)
– IREC (Institut de Recerca En Energía de Catalunya)

– LNEC (Laboratório Nacional de Engenharia Civil)
– EDP Distrubuiçao (Energias de Portugal)
– Ajuntament de Barcelona
– Câmara Municipal de Lisboa
– Bristol City Council
– Wessex Water

The University of Exeter was responsible for the coordination of the methodologies and impact assessments carried out in the three respective cities.

The Centre for Water Systems (CWS) at the University of Exeter provided its expertise and guidance in the fields of flood risk analysis and impact assessment, along with the development of methodologies and tools
to integrate flood, traffic and risk analyses for the Barcelona and Bristol research sites.

CWS has an extensive reputation in projects around the world that relate to climate change adaptation and impact assessments within the field of flood risk management. Other areas of expertise in CWS includes data mining and analytics, smart systems, decision support, hydraulics, hydrology, numerical modelling, optimisation, socio-technical and systems thinking.

Expert contact info:

University of Exeter, Centre for Water Systems
Phone number: +44 (0)1392 722079
Prof Slobodan Djordjevic:
Dr Albert Chen:
Dr Barry Evans:

College of Engineering, Mathematics and Physical Sciences University of Exeter, North Park Road. Exeter, EX4 4QF, United Kingdom

Tools & Results


Flood direct damage assessments

Impact assessment & cascading effects


The Direct Damage Assessment data for the Bristol case study is derived via the analysing water depths that are in contact with buildings to estimate the damages based on the building use and the associated depth-damage relationship. The functions for Bristol are obtained from the Multi-colour Manual (MCM ). The MCM contains information derived from historical insurance data that relates damage estimates to properties based on surrounding flood depth and said properties land use classification. The dataset herein presented outlines the aggregated damages to flooded buildings based on their exposure to flood waters and their respective depth-damage curves. 


Flood Risk Assessment tool for electrical assets

Impact assessment & cascading effects


This tool seeks to help with the strategic planning and future operational decisions oriented to prevent possible problems caused by extreme flooding events in the electrical network through the risk assessment and major risk identification on electrical assets, the estimation of associated costs and reliability indices. The tool has been developed on the open-source GIS platform QGIS, building on FEMA fragility curves and the methodology presented in “Electrical Grid Risk Assessment Against Flooding in Barcelona and Bristol Cities” paper.


Impact quantification indices in the electrical network

Impact assessment & cascading effects


GIS-based methodology designed for the assessment of electrical substations and distribution centres in case of extreme flooding events and extensible to other climate extreme events such as earthquakes, heat waves, and extreme windstorms if electric poles are also included into the assessment. This methodology has been thoroughly explained in “Electrical Grid Risk Assessment Against Flooding in Barcelona and Bristol Cities” paper.

Tabulated results

Integrated flooding – electrical simulations Bristol 

Impact assessment & cascading effects


Tabulated global results generated from the integrated flooding-electrical simulations in Barcelona and Bristol cities. This provides additional information about hazard potential, level of risk, and the estimated cost quantification of these risks for different return periods and scenarios provided in the flooding models.

Assessment results Maps in image format

Integrated flooding – electrical simulations in Barcelona and Bristol 

Impact assessment & cascading effects


Hazard and risk maps were generated from the integrated flooding-electrical simulations in Barcelona and Bristol cities. The Maps indicates the locations with hazard potential, level of risk, and the estimated cost quantification of these risks for different return periods and scenarios provided in the flooding models.


Flood tangible damage assessment in Barcelona and Bristol

Impact assessment & cascading effects


Hydrodynamic outputs (flood depths) were used to feed the flood direct damage model. This model, based on this information, detailed land use maps and tailored flood depth damage curves, provided economic risk maps for different return periods related to current and future scenarios (including Business as usual and Adaptation scenarios).


Flood intangible damage assessment in Barcelona

Impact assessment & cascading effects


Hazard maps were also combined with vulnerability maps to provide flood risk maps for pedestrian and vehicles. Risk maps were obtained for different return periods related to current and future scenarios (including Business as usual and Adaptation scenarios).