NH039-0003
Exploring multi-hazard interrelationships: A case study of Central Virginia Planning District Commission Hazard Mitigation Plan Update
Exploring multi-hazard interrelationships: A case study of Central Virginia Planning District Commission Hazard Mitigation Plan Update
Wednesday, 16 December 2020
Poster
Abstract:
Many regions in the U.S. are impacted by events that include more than one hazard - natural or man-made, that impact the same area during the same time period. These events are called multi-hazard events, compound events, cascading events, etc. The interaction of different hazards can lead to an impact that is greater than the single hazard events. There seems to be an increase in compound disasters in recent years and is expected to rise in the future.
There are some quantitative and theoretical risk models in literature for mapping the relationships between hazards, however, they are not often used in decision making. Exploring and understanding relationships between hazards and their impacts on communities is important for the effectiveness of preparedness plans. Conventional risk assessment methods normally only consider one driver or hazard at a time, which likely underestimates risk. The current hazard mitigation plans at the regional or local level often focus on profiling individual hazards instead of considering connected chains of events.
This study explores various concurrent and causal interrelations between hazards in the Central Virginia Planning District Commission (CVPDC) region of Virginia. The CVPDC is a defined geographic area surrounding the City of Lynchburg in Central Virginia. For the 2020 CVPDC hazard mitigation plan update, we developed weighted network diagrams to depict relationships between hazards and their impacts on people, built environment, and infrastructure.
In the network diagram, natural and man-made hazards are represented by nodes that are connected by edges. This study used information from various sources to build the interrelationship. First, the analysis of the region's disaster history provided the basis for the identification and generalization of hazard interrelationships - the edges. The edges represent two types of primary relations between hazards - causal and concurrent. A causal relation is one where one hazard is a prerequisite for a correlated hazard. A concurrent relation means hazards that are probable to occur at the same time due to common root causes. Second, hazard ranking surveys were used to collect information about nodes. The size of each node is a weighted sum of two categories: hazard’s impact (catastrophic, critical, limited, and negligible) and frequency of the hazard (highly likely, likely, possible, and highly unlikely). Data about impact and frequency was collected from experts in the technical advisory committee and the community.
Hazard interrelations are not often considered in local hazard mitigation planning and decision making. Multi-hazard network models can help develop timelines and guide decision making and planning at local level. These network graphics could have multiple applications like communicating the risks to local officials and residents. This could be further considered in making zoning and land use decisions for communities with a strong history of multi-hazard events.
There are some quantitative and theoretical risk models in literature for mapping the relationships between hazards, however, they are not often used in decision making. Exploring and understanding relationships between hazards and their impacts on communities is important for the effectiveness of preparedness plans. Conventional risk assessment methods normally only consider one driver or hazard at a time, which likely underestimates risk. The current hazard mitigation plans at the regional or local level often focus on profiling individual hazards instead of considering connected chains of events.
This study explores various concurrent and causal interrelations between hazards in the Central Virginia Planning District Commission (CVPDC) region of Virginia. The CVPDC is a defined geographic area surrounding the City of Lynchburg in Central Virginia. For the 2020 CVPDC hazard mitigation plan update, we developed weighted network diagrams to depict relationships between hazards and their impacts on people, built environment, and infrastructure.
In the network diagram, natural and man-made hazards are represented by nodes that are connected by edges. This study used information from various sources to build the interrelationship. First, the analysis of the region's disaster history provided the basis for the identification and generalization of hazard interrelationships - the edges. The edges represent two types of primary relations between hazards - causal and concurrent. A causal relation is one where one hazard is a prerequisite for a correlated hazard. A concurrent relation means hazards that are probable to occur at the same time due to common root causes. Second, hazard ranking surveys were used to collect information about nodes. The size of each node is a weighted sum of two categories: hazard’s impact (catastrophic, critical, limited, and negligible) and frequency of the hazard (highly likely, likely, possible, and highly unlikely). Data about impact and frequency was collected from experts in the technical advisory committee and the community.
Hazard interrelations are not often considered in local hazard mitigation planning and decision making. Multi-hazard network models can help develop timelines and guide decision making and planning at local level. These network graphics could have multiple applications like communicating the risks to local officials and residents. This could be further considered in making zoning and land use decisions for communities with a strong history of multi-hazard events.