For every risk and riskscenario identified in the previous risk identification stage, the risk analysis process carries out a detailed (and if possible quantitative) estimation of the probability of its occurrence and the severity of the potential impacts1)EC (2010). Risk Assessment and Mapping Guidelines for Disaster Management. COMMISSION STAFF WORKING PAPER. Brussels, 21.12.2010 SEC(2010) 1626 final..
The outcome of this step is a risk value for each relevant climatehazard or combination of hazards.
Guidelines
A risk value is the result of a combination of the probability of a certain hazard and its consequences on an exposed object and can, for example, be expressed in terms of low, intermediate, high and very high. Determining this value includes the process of defining indicators for risk components, gathering data and aggregating indicators and risk components. This is a considerable task in the development of an adaptation strategy, but will provide important information on the actual vulnerability of the area or asset. The first step in a risk analysis is a thorough preparation.
Quantitative risk assessment
The risk value for each climatehazard is calculated as: hazardimpact x probability of occurrence. The focus lies, therefore, in determining this probability and impact for each hazard that has been identified. To assess the intensity and probability of a hazard, the specific hazardscenario under examination has to be defined first. For example, the scenario might be a five day period of extreme precipitation resulting in fluvial flooding. The scenario can be based on historical data from prior occurrences or on (future) projections. If multiple hazard scenarios are to be examined, intensities and probabilities might have to be estimated multiple times, once for every hazardscenario.
Given the scenario, you can then specify the hazard probability based on the data for the indicators defined in the previous modules, for example, by analysing and aggregating corresponding historical data, employing climate projections or simulation methods, or using expert judgement. For the extreme precipitation scenario from above, the historical number of days in a year with a precipitation above a critical threshold of x l/m²/hour could be calculated and used to estimate the hazard probability.
Impact
The hazard intensity can be assessed in similar fashion: you might correlate historical precipitation data to historical data on flood depth and coverage area from the same time period, giving you an inkling of the hazard intensity following a specific amount of precipitation. Alternatively, the historical precipitation data might be fed into a flood simulation model of your city to calculate the relevant hazard indicators. As an example for heat waves, you could relate historical monthly or weekly temperature data to monthly or weekly mortality rates.
Next to assessing the hazard intensity, the scores for vulnerability should be determined. These scores can be acquired by aggregating the normalised and weighted output values for indicators addressing the risk components sensitivity and coping capacity.
Once vulnerability scores and hazard intensity have been assessed, the expected impact of a given hazard on an exposed object under a specific scenario can be determined. The process of estimating the expected consequences of a hazardscenario is called Consequence Analysis. In the context of IVAVIA, it is the process of relating hazard intensities to expected consequences. There is no hard and fast standard process, but rather a suite of tools, models, and approaches that may be employed, depending on the data and resources (in terms of personnel, time, and funds) available. Here are some of the most frequently:
Damage functions correlate hazard intensity, often quantified using a single measure, with potential damage. For example, flood depth-damage functions relate flood depth to damages; these may be damages in terms of monetary values, reductions in travel speed, number of fatalities, or other damages. Sources for damage functions include, for example, the JRC Technical Report on global flood depth-damage functions 2)
Jan Huizinga, Hans de Moel, Wojciech Szewczyk, Global flood depth-damage functions, Methodology and the database with guidelines, JRC, 2017: http://publications.jrc.ec.europa.eu/repository/bitstream/JRC105688/global_flood_depth-damage_functions__10042017.pdf or the standard method for damage and casualty estimation in the Netherlands 3)Kok, Huizinga, Vrouwenvelder, and Barendregt, Standaardmethode 2004: schade en slachtoffers als gevolg van overstromingen, Ministerie van verkeer en waterstaat, 2004
Computable General Equilibrium models can be used to model links between economic sectors and subsequently cascading effects between different sectors resulting from a hazardous event. They use input-output tables, i.e. symmetrical matrices describing transactions between economic sectors, and combine them with standard assumptions about economic behaviour of households, firms, and governments to analyse the responses of the economy.
Computer simulations are computer programs that use abstract digital representations to imitate (parts of) real or hypothetical processes, mechanisms, or systems. Depending on their level of detail they may require quite a lot of data and other resources, as well as expert knowledge to calibrate the underlying models and validate their results.
Inter-/Extrapolation may be used if only historical data on past intensities and consequences is available, but no further sources on their correlation are on hand. In this case the historical data may be used to inter- or extrapolate the consequences resulting from given hazard intensities.
Expert judgement may be employed if absolutely no other data is available. Here, local experts are employed to estimate the consequences resulting from the given hazard intensities.
Multi-risk analysis
The above addresses a single-risk analysis, estimating the risk of a singular hazard in isolation from other hazards or risk scenarios4)EC (2010). Risk Assessment and Mapping Guidelines for Disaster Management. COMMISSION STAFF WORKING PAPER. Brussels, 21.12.2010 SEC(2010) 1626 final.. The challenge of multi-risk assessments is to adequately take account of possible follow-on effects (also: knock-on effects, domino effects or cascading effects) among hazards, i.e. the situation where one hazard causes one or more sequential hazards. The following work steps are recommended:
Identification of possible multi hazard scenarios, starting by a given top event and evaluating the possible triggering of other hazards or events leading to hazards;
Risk estimate for each hazard and adverse event and for the multi-risk scenarios.
Software tools such as decision support system for mapping multiple risk scenarios can be used and facilitate the visualisation and information and the running of scenarios.
Experiences
No experiences available yet.
Supporting tools and methods
IVAVIA – Workflow Support
The IVAVIA Workflow Support is a tool for supporting the automation of some steps of the workflow for risk-based vulnerability assessments of Impact Chains.
The IVAVIA workflow Support tool supports the selection of an Impact Chain from the Impact Chain Editor ICE+ [hyperlink], fetching data from the IVAVIA database that match the indicators in the Impact Chain Diagram and invoking the RIVAS tool for computing risk component values based on the fetched data. As a first prerequisite, therefore, you need to create at least one Impact Chain for your assessment. As second prerequisite, you need to gather the required hazardindicator data, socio-economic data, and other data and import them into the IVAVIA database. Thereafter, the RESIN Workflow Tool can be used.
Select an Impact Chain Diagram corresponding to a scenario (city, spatial resolution, timeframe) that you want to investigate. It will automatically be imported from the Impact Chain Editor ICE+. The scenario description and the Impact Chain Diagram will be displayed
Select the indicator data normalization method, the aggregation method, and the weighting method. If you are not an expert in statistics, you may rely on the offered default methods.
After you have made all required selections, you may press the “Calculate” button
The “Download results” button finalizes the IVAVIA part of the RESIN workflow support software. It will download three files:
1) the selected Impact Chain Diagram as a native JSON file (can be reimported by ICE+);
2) the table of values per zone as a CSV file (can be read with Excel);
3) the color-coded zone maps as shape files (GeoJSON file).
When using the DSC: Upload the CSV or JSON file to the respective form in the Decision Support Center [hyperlink when available]
Nb. You may proceed from the workflow support software with fetching suitable adaptation options from the RESIN Adaptation Options Library that match the Impact Chain Diagram. Again, you may download the AOL results and manually upload them to your project in the RESIN e-Guide.
IVAVIA – Quantitative risk assessment
The IVAVIA tool supports the user in performing a risk-based Vulnerability Assessment by facilitating the understanding of cause-effect relationships of climate change, identify geographical hotspots of vulnerability and risk, and assess what impact on people, economy, infrastructure and built-up area under study can be expected now and for the future due to the changing climate
Modules 3, 4, 5 and 6 of IVAVIA support the development and performance of a quantitative vulnerability assessment. The Impact Chains and other outputs as defined in Modules 0, 1 and 2 are used as a starting ground for the assessment. The quantitative assessment requires a considerable amount of time and effort of city administrators and experts. A good part of this effort is dedicated to acquiring the required socio-economic and infrastructure data.
Guidance
Go to the description of Module 3 and follow the instructions to identify indicators and acquire data for the risk components: hazards, drivers, stressors, impacts, sensitivity, and coping capacity;
Go to the description of Module 4 and follow the instructions to normalize, weight and aggregate the indicators;
Go to the description of Module 5 and follow the instructions to aggregate components to vulnerability and risk scores;
Go to the description of Module 6 and follow the instructions to present the outcomes of IVAVIA;
When using the DSC: Document the outcomes of all modules in the respective form in the Decision Support Center [hyperlink when available]
3Di
3Di is an interactive model for water management and can map out water flows and the effects of flooding, heavy precipitation and drought, both for the current situation – for example during heavy rainfall – and for climatological scenarios in urban and rural environments.
3Di is a complex sophisticated tool to model hydrodynamic processes. It offers two modes of usage:
Directly: the user (with a background in GIS and hydrology) can explore the model by him-/herself. In this case, the user will be provided with online guidance on how to use the tool and can participate in a training.
Support by a local partner: the model building will be performed by a local expert of the 3Di team.
CLIMADA Natural catastrophe damage model
CLIMADA is a probabilistic natural catastrophe damage model, that also calculates averted damage (benefit) thanks to adaptation measures of any kind (from grey to green infrastructure, behavioural, etc.). It is based on the Economics of ClimateAdaptation (ECA) Methodology, Method is very quantitative and requires a high level of expertise to operate.
Using the methodology guide, determine the risk levels for your climate threats and record these in your workspace.
Blue Green Dream
Blue green dream is a tool used in a commercial consultancy process that calculate how adaptation measures influence water, energy, comfort and financial costs/savings. It supports the modelling and calculation of water management situations before and after adaptation measures have been taken.
To use, contact Climate-KIC. Record the results (water management related risks) in your workspace.
RAMSES Vulnerability assessment
The RAMSES ‘Vulnerability assessment’ worksheet developed is a step-by-step description of steps to take in a vulnerability assessment, which is part of a complete risk analysis.
Follow the instructions in the workbook ‘Vulnerability assessment’, provided as an annex in the guidance document.
Use the results as an input for a complete risk analysis (for overview, see scheme above).
Record the results in your work space.
Risk systemicity questionnaire
The Risk Systemicity Questionnaire is an Excel based tool where users are asked to consider the relative likelihood of a broad range of risks in their cities.
EC (2010). Risk Assessment and Mapping Guidelines for Disaster Management. COMMISSION STAFF WORKING PAPER. Brussels, 21.12.2010 SEC(2010) 1626 final.
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Jan Huizinga, Hans de Moel, Wojciech Szewczyk, Global flood depth-damage functions, Methodology and the database with guidelines, JRC, 2017: http://publications.jrc.ec.europa.eu/repository/bitstream/JRC105688/global_flood_depth-damage_functions__10042017.pdf
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Kok, Huizinga, Vrouwenvelder, and Barendregt, Standaardmethode 2004: schade en slachtoffers als gevolg van overstromingen, Ministerie van verkeer en waterstaat, 2004