Disaster Risk Assessment: A Step Towards Disaster Risk Reduction

Dr Girish Chandra Joshi is a Senior Consultant, Uttarakhand State Disaster Management Authority, Government of Uttarakhand.

A pro-active approach towards

Disaster management and focus on reducing and managing the risk rather than managing the disaster has brought global attention towards Disaster Risk Reduction (DRR). Multi-stakeholder inclusion in all stages of the disaster management cycle provides a platform for interaction and differentiated responsibilities for all sections of society. Risk quantification involves assessment and quantification of hazard, vulnerability and exposure. Overlapping the probability of any hazard, type and level of vulnerability and extent of exposure results in a spatial risk. Special attention to socio-economic factors is required for reducing vulnerability and exposure.

A risk-free world does not exist, and our society must learn to cope with and minimize the impact of hazards in the course of our development. During the past 70 years, risk management practices have changed from initially focusing on engineering solutions to a modern complex framework that employs various measures to manage risk. This buffet of measures includes planning to gradually move or improve critical infrastructure, attempts to control the hazards, e.g., by building river embankments, and financial measures to transfer the risk. Thereby, it is practical to understand risk as being the function of hazard, vulnerability and exposure.

Accurate quantification of the risk allows us not only to deliver accurate assessments of the current risk but also enables decision-makers to drive development in the desired direction to minimize risk, assessing which of the main constituents of risk (hazard, exposure and vulnerability) drive the risk. 

The basis of proper management of risk is first to study and quantify the risk. Through risk analysis, it will be possible to answer questions such as: What is the influence of urbanization on the social vulnerability towards hazards? Do traditional coping mechanisms effectively address the increased intensity of hazards? How can we achieve the maximum effect of risk mitigation through changes in exposure, coping capacities, susceptibility and adaptive capacities? What are these interactions between different social groups?

These questions and many more are of key importance to understand “risk area” and especially to develop and apply risk mitigation strategies. However, finding answers to these challenges is anything but simple. One cannot solely focus on examining current risk patterns or the lessons learned from past disasters. As is especially true of a nation under rapid development, it is necessary to consider future trends since the risk is increasingly shaped by the interaction of two megatrends: urbanization and climate change.

Risk Assessment

Investigation of the Centre for Research on the Epidemiology of Disasters (CRED) data, which supposedly is incomplete for India, shows that the major disasters in India, in terms of economic loss and life, relate to floods, drought, storm, earthquakes and epidemic disease (viral, bacterial and parasitic diseases). The risk posed by a specific hazard can be described as a function of the magnitude of the hazard, the vulnerability towards the hazard and the exposure (severity) of the impact:

Risk = f (hazard, vulnerability, exposure)

•  Hazards: Quantitatively defined by the likely frequency of occurrence of different intensities for different areas, derived from historical data sets and covering events including earthquakes, landslides, flash floods and industrial hazards.

• Exposure: People, property, systems, or other elements present in hazard zones that are thereby subject to potential losses; with options for disaggregation of incidence by income level (i.e., impact on the poor), geographic area (i.e., to identify areas for urgent intervention), and sector (e.g., government/public, commercial/ industrial, residential), and,

• Vulnerability: Quantitative and qualitative (proxy) measures of the damages and losses incurred to the exposed elements-at-risk (e.g., people, property, systems) by different intensities of the various hazards considered.

The relationship between these three aspects of understanding risk is illustrated in Figure 1.

Hence, development of risk maps requires aggregation of spatial analysis of hazard, vulnerability and exposure. Risk-modelling can integrate various dynamic parameters of hazard, vulnerability and exposure.

Specifically, the different modules of any risk assessment are:

•Hazard Modules: It links to data of historical data, hazard extent and models to predict hazard frequency and intensity.

• Exposure Data: Accurate, up-to-date topographic maps, land-use maps, asset maps, classification, valuation and location of critical infrastructure can be used by the system.

• Vulnerability and Damage Module: The vulnerability module includes software tools for developing physical vulnerability functions for each hazard and class of asset considered. The vulnerability module can also be used to assign specific vulnerability functions to the exposed elements.

• Loss Module: This module describes and processes probabilistic losses at various user-defined return periods for selected hazards.

•  User-added Modules: Examples are (a) Climate Change Scenarios – to process the probable loss characteristics over a modelled future climate change scenario; (b) rapid near real-time loss estimation – to estimate probable damage modelled on a specific hazard event such as a cyclone track or avalanche.

Risk Management

Risk management is the process through which risk is evaluated before strategies are introduced to manage and mitigate the threat (Smith and Petley, 2008). As Crozier (2005) noted, the key drivers for the successful management of risk must be an awareness of the threat, a sense of responsibility, plus a belief that the threat can be managed or at least reduced.

In an ideal world, the risk management procedure follows a clear set of priorities in which the highest levels of risks are addressed first. However, to develop such a priority list, a detailed quantitative risk assessment of all relevant factors and processes is required.

This is a difficult task, not least because of the need to balance the relative significance of losses from high and low-frequency events. Carter (1991) showed that, in most cases, the activities contained in hazard management could be represented as a cycle (Figure 2). Risk management itself is often considered to be focused upon the prevention, mitigation and preparedness elements of this cycle, although the other elements are also important. Prevention, which forms part of this cycle, is only achievable to a limited extent.

Risk management focuses on the aspect of pre-disaster protection in the risk reduction cycle. However, this does not mean the other half of the cycle will be completely neglected. Therefore, the basis of a risk management system will be developed and be expanded to act as a basis for post-disaster recovery. For example, the information generated for pre-disaster protection can be used (perhaps after adaptation) for pinpointing areas that most urgently require post-disaster recovery and for the selection of effective and efficient post-recovery measures. Besides, due to the modular approach of the system, decision-making and action protocols for pre-disaster protection can be supplemented with protocols for post-disaster recovery. As shown in Figure 2, pre-disaster protection consists of risk assessment, mitigation, preparedness and emergency plans. As shown above, the primary elements of pre-disaster protection are:

• Risk Assessment: Involves the identification of a hazard, the accumulation of data and the preparation of loss estimates.

•  Mitigation: Measures are taken in advance of disaster strikes, aimed at decreasing or eliminating the loss. Various long term measures, such as the construction of engineering works, insurance and land-use planning are used.

• Preparedness: Reflects the extent to which a community is alert to disaster and covers short-term emergency planning, hazard warning and temporary evaluation procedures, plus the stockpiling of supplies.

The capabilities of the risk assessment and associated management systems will allow for expansion in the future, including, amongst others, functionalities facilitating other mitigation strategies, such as the construction of engineering works, insurance schemes and land-use planning.

Disaster Risk Reduction

There is a paradigm shift underway in disaster management (and the allocation of associated government/donor funding), both in India and worldwide, moving from a primary focus on recovery and reconstruction to an emphasis on disaster risk reduction (DRR). This requires a detailed and holistic assessment of the risks present in a given geographical and socio-economic context, which may then be used to inform a process of risk management, reducing the impact of potential disasters in the future.

However, although risk assessment and risk management processes are increasingly being used by government agencies to estimate and manage risks associated with natural hazards, these tools have many inadequacies and may not optimally serve all countries. Holistic and optimized risk assessment and management requires a thorough understanding, among others, of the societal needs and perceptions, the political system, development plans, hazards, vulnerability towards hazards and change in the climate. The importance of socio-economic factors in choosing the right risk management strategies is an important reason for strongly basing the current study on empirical data.

Holistic management of risk identifies actions to be taken to reduce the impact of extreme events before, during and after extreme events, and include preventive technical/structural measures and socio-economic aspects to reduce vulnerability to hazards. It is important to note that disaster risk management and management of climate change impacts share the same objectives, therefore, presenting a major challenge and opportunity to bridge current disaster risk management efforts with climate change adaptation measures.

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