The danger of mapping risk from multiple natural hazards

In recent decades, society has been greatly affected by natural disasters (e.g. floods, droughts, earthquakes), losses and effects caused by these disasters have been increasing. Conventionally, risk assessment focuses on individual hazards, but the importance of addressing multiple hazards is now recognised. Two approaches exist to assess risk from multiple-hazards; the risk index (addressing hazards, and the exposure and vulnerability of people or property at risk) and the mathematical statistics method (which integrates observations of past losses attributed to each hazard type). These approaches have not previously been compared. Our application of both to China clearly illustrates their inconsistency. For example, from 31 Chinese provinces assessed for multi-hazard risk, Gansu and Sichuan provinces are at low risk of life loss with the risk index approach, but high risk using the mathematical statistics approach. Similarly, Tibet is identified as being at almost the highest risk of economic loss using the risk index, but lowest risk under the mathematical statistics approach. Such inconsistency should be recognised if risk is to be managed effectively, whilst the practice of multi-hazard risk assessment needs to incorporate the relative advantages of both approaches

Modelling multi-hazard risk assessment: A case study in the Yangtze River Delta, China

Multi-hazard risk assessment (MHRA) has become a major concern in the risk study area, but existing approaches do not adequately meet the needs of risk mitigation planning. The main research gap in the existing approaches was identified that they cannot consider all hazard interactions when calculating possible losses. Hence, an improved MHRA model, MmhRisk-HI (Model for multi-hazard Risk assessment with a consideration of Hazard Interaction), was developed. This model calculates the possible loss caused by multiple hazards, with an explicit consideration of interaction between different hazards. A more complete perspective, the regional disaster system perspective, was selected as the basic theory, and two categories of multi-hazard risk expressions were combined in the model construction. Hazard identification, hazard analysis, hazard interaction analysis, exposure analysis and vulnerability analysis are the five basic modules of the developed model. The concept of hazard-forming environment was introduced into the MHRA research as the basis for hazard identification, hazard analysis, and hazard interaction analysis. The methods used for exposure analysis depend on the scale of the region to be addressed and the assessment units. A Bayesian Network was adopted to calculate the loss ratio in the vulnerability analysis. This developed model was applied into the Yangtze River Delta (YRD) and validated by comparison with an observed multi-hazard sequence. The validation results (simulation results are consistent with observed results in 76.36% of the counties, and the deviation of an estimated aggregate loss value from its actual value is less than 2.79%) show that this model can more effectively represent the real world, and that the outputs, possible loss caused by multiple hazards, obtained with the model are reliable. The outputs can additionally help to identify which area is at greatest risk (of loss), and allow a determination of the reasons that contribute to the greatest losses. Hence, it is a useful tool which can provide further information for planners and decision-makers concerned with risk mitigation

5th Global Summit of GADRI: Engaging Sciences with Action

31 August to 1 September 2021, Virtual Intercontinental Conferenc

Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation: Special Report of the Intergovernmental Panel on Climate Change

This Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) has been jointly coordinated by Working Groups I (WGI) and II (WGII) of the Intergovernmental Panel on Climate Change (IPCC). The report focuses on the relationship between climate change and extreme weather and climate events, the impacts of such events, and the strategies to manage the associated risks. The IPCC was jointly established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), in particular to assess in a comprehensive, objective, and transparent manner all the relevant scientific, technical, and socioeconomic information to contribute in understanding the scientific basis of risk of human-induced climate change, the potential impacts, and the adaptation and mitigation options. Beginning in 1990, the IPCC has produced a series of Assessment Reports, Special Reports, Technical Papers, methodologies, and other key documents which have since become the standard references for policymakers and scientists.This Special Report, in particular, contributes to frame the challenge of dealing with extreme weather and climate events as an issue in decisionmaking under uncertainty, analyzing response in the context of risk management. The report consists of nine chapters, covering risk management; observed and projected changes in extreme weather and climate events; exposure and vulnerability to as well as losses resulting from such events; adaptation options from the local to the international scale; the role of sustainable development in modulating risks; and insights from specific case studies

Development of a flash flood confidence index from disaster reports and geophysical susceptibility

The analysis of historical disaster events is a critical step towards understanding current risk levels and changes in disaster risk over time. Disaster databases are potentially useful tools for exploring trends, however, criteria for inclusion of events and for associated descriptive characteristics is not standardized. For example, some databases include only primary disaster types, such as ‘flood’, while others include subtypes, such as ‘coastal flood’ and ‘flash flood’. Here we outline a method to identify candidate events for assignment of a specific disaster subtype—namely, ‘flash floods’—from the corresponding primary disaster type—namely, ‘flood’. Geophysical data, including variables derived from remote sensing, are integrated to develop an enhanced flash flood confidence index, consisting of both a flash flood confidence index based on text mining of disaster reports and a flash flood susceptibility index from remote sensing derived geophysical data. This method was applied to a historical flood event dataset covering Ecuador. Results indicate the potential value of disaggregating events labeled as a primary disaster type into events of a particular subtype. The outputs are potentially useful for disaster risk reduction and vulnerability assessment if appropriately evaluated for fitness of use.Campus Lima Centr

National systems for managing the risks from climate extremes and disasters

This chapter assesses how countries are managing current and projected disaster risks, given knowledge of how risks are changing with observations and projections of weather and climate extremes, vulnerability and exposure, and impacts. It focuses on the design of national systems for managing such risks, the roles played by actors involved in the system, and the functions they perform, acknowledging that complementary actions to manage risks are also taken at local and international level