Risk Assessment

How We Assess Risk

hazard identification

UVI is working closely with the Steering Committee to review natural hazards of concern. This analysis includes hazards identified in the 2014 VITEMA plan, as well as new hazards linked to climate change (e.g., temperature increases or heat waves, sea-level rise, etc.). This technical analysis will confirm the selection of prioritized hazards derived from close stakeholder input and provide an overview of the methodology to be applied to each hazard - the approach that will be utilized to determine either the intensity of or susceptibility levels of each hazard, taking into account available information and any major data limitations as applicable. UVI anticipates that the hazards of concern will include earthquake, riverine flooding, coastal flooding and erosion (due to hurricane-induced storm surge, and/or waves), rain-induced landslides, droughts, wildfires, heat waves and/or steady increases in temperatures, etc. Based on its assessment of available data and review of appropriate hazard models, and in coordination with national hazard model and mapping efforts, UVI will develop a memorandum report outlining the proposed approach for addressing hazard, building profiles and its modeling. This will report will outline approaches that take into account climate change variability.

Climate Change Variability

In a major shift from previous planning efforts, UVI will include climate change scenarios in its hazard profiles and models. UVI, through their staff and external subject-matter experts, is collecting and utilizing the best available data to develop optimistic, moderate, and pessimistic climate change scenarios (i.e. rainfall patterns, temperature, sea-level increases, future storm intensity and frequency) for two temporal scenarios: 2020 and 2050. These times horizons represent the times when mitigation strategies will be developed (2020), and when many new buildings typically reach their 30-year design lifetime.

Natural Hazard and Community Profiles

In addition to the hazard profiles being developed as part of this planning effort, UVI is also developing inventory maps and databases of the physical and built environment. This includes databases for general building stock, critical facilities and infrastructure; environmental profiles which include maps and databases of important environmental features; and social and economic profiles that will help outline dynamics of the Territory's society and economy.

Hazards Profile

Where possible, UVI is using existing hazard models in coordination with FEMA, its contractors and other national agencies for updating and developing hazard profiles for each of the identified and prioritized hazards in the Territory. The resulting UVI hazard profile will include a brief outline of each hazard and its potential manifestation within the Territory, a description of the main elements utilized to determine or characterize each hazard, along with a map that delineates the spatial extent of the hazard. To compute the spatial extent of the hazard, UVI will rely as much as possible on existing data collected or computed by FEMA and other federal agencies.

UVI expects to utilize and augment existing studies that may be developed by Federal agencies by incorporating new flood moderating elements such as wetlands or coral reefs, or more detailed drainage infrastructure maps (which will be collected as part of this effort), or different forcing such as sea-level rise, or intensification of rainfall during storms. For each hazard description, UVI is incorporating, when applicable, long-term meteorological data to help understand past trends and compute probabilities of occurrence. Special consideration is given to events that occurred in succession, or that can be triggered by another event (e.g., wildfires and drought). The description will also incorporate potential impact of climate change on that hazard, when applicable, based on regional and/or global climate projection information. A key distinction will be made between natural hazards that are potentially exacerbated by climate change and those that are not.

Physical and Built Environment Profile

UVI is developing an updated inventory database of general building stock (by occupancy class: residential, commercial, industrial, institutional buildings) and critical facilities (health, police and fire departments, etc.) and infrastructure (potable water supply, sanitation, drainage, electricity supply, solid waste collection, housing, and roads). As much as possible, UVI is also developing a database to collect information on number, typology, construction area, and value of assets. UVI is working with partners to collect and integrate attributes that may be necessary to address function and loss as part of its risk profile. These inventory databases will become inputs in the hazard and risk models.

Natural Environment Profile

UVI is developing maps and databases of the bio-physical characteristics of natural systems. Special attention is paid to mangrove forests and wetlands, coral reefs, and seagrass beds. These profiles will become inputs in both hazard and sustainability models/plans and will help planners and emergency management practitioners alike understand the importance of natural systems and the role they play in reducing the impacts of hazards and climate change. Understanding these systems and their functions across critical habitats, and how the systems interact with humans or the built environment are an important part of UVl's planning efforts.

Social and Economic Profile

UVI is incorporating social and economic profiles into its planning efforts. An assessment of the social and economic dynamics in the Territory helps provide an understanding of the potentially vulnerable groups and sectors of the community. Macro-economic, population and housing information is being collected and used to highlight and understand the characteristics of the economy, dependencies, growth trends and/or areas of stagnation. UVI is also collecting and analyzing sociologic and anthropologic data of the different groups living in the Territory. This data will provide insight on how the Territory's communities and economy may be affected by natural hazards and/or climate change, but also help to identify assets and systems these communities rely on to reduce the impacts of hazards. Results of this analysis will also become important inputs in sustainability models when projecting future growth trends as well as help to characterize function and dependencies of social institutions, sectors and systems in view of building resilience (NIST, 2016).

Assessing Vulnerability

A critical aspect of UVl's approach to assessing vulnerability is that it makes use of the inventories and profiles developed in the section above. Under this task, the term 'vulnerability' is broadened to be dependent both on the forcing parameter (physical impact of a hazard event) and the exposed elements (societal, infrastructural, economic, environmental and institutional dimensions) that affect the Territory's capacity to respond to the impacts of hazards.

Physical Vulnerability Analysis

Physical vulnerability is an important element for quantifying economic losses and risk. Physical vulnerability is most commonly quantified using vulnerability curves (stage-damage functions), fragility curves, and/or damage matrices which quantify the percent of damage or loss expected from a defined level of hazard intensity. During this effort, UVI is building vulnerability functions for building stock, critical facilities and infrastructure that will help characterize the performance of identified assets to a hazard.

Vulnerability, Resilience and Functionality

As highlighted in the physical and built environment profile discussion, the development of the inventory database is important for incorporating the concept of resilience into the Plan. Here, in partnership with the National Institute of Science and Technology (NIST), UVI incorporates function and loss parameters into vulnerability functions to help quantify how different types of hazards can impact the functionality of critical infrastructure and essential buildings, and their ability to deliver essential services to the Territory. UVI works closely with the Center for Infrastructure Defense at the US Naval Post-Graduate School (NPS), to quantify the impacts of hazards on the functioning of critical infrastructure; to evaluate the interdependency of critical infrastructure in the Territory and potential ensuing and cascading effects if one of the elements fails. The NPS's inputs will be important to help identify vulnerable infrastructure and critical facility elements whose failure can lead to the loss of critical services for a large portion of the population. This analysis will help determine how long it would take, under pre-mitigation conditions, for the recovery of function in critical buildings or facilities, or in buildings or facilities that were determined to be most important for communities to recover faster. The incorporation of these factors are essential for the design of mitigation strategies and options that increase the resilience of critical systems, ensure the delivery of vital services, and ultimately reduce functionality loss. As part of its Vulnerability Analysis, UVI will ensure that its vulnerability models are developed for identified assets using analytical and statistical methods that are complemented with expert or heuristic judgments by working closely with NIST and NPS.

Linking Built, Natural and Socio-Economic Environments

In addition to understanding the physical impacts to the built environments, UVI as part of its vulnerability assessment, will integrate information from the characterization of the built, natural and socio-economic profiles to understand how people and institutions depend on the built and natural environment. This will help better characterize the vulnerability of the population, and the types of critical services that need to be maintained after a disaster to reduce recovery time.

Estimating Potential Losses

Risk Estimation

UVI is developing a risk model based on standard risk assessment methods to provide more accurate loss estimates for the Territory. Our risk assessment model will integrate improved hazard information (i.e. see hazard profiles description that incorporate data on local hazard conditions), Territory-specific asset inventories, and vulnerability information to estimate losses. In a departure from previous efforts, UVI will incorporate in its risk assessment, the potential risk reduction benefits provided by natural systems (mangroves, coral reefs, etc.). Some hazards will be handled by calculating probabilistic losses for specific return periods (i.e. 50-, 100yr return periods), and others will be estimated by using more qualitative models. Where possible, losses will be calculated for every exposure type, and the associated rate of occurrence, to assess the total loss for that event. This information will be computed in a statistical model to estimate the total probable losses across entire Territory, and by island. This will be presented for each asset class in the exposure database. For some types of hazards and other types of sectors or aspects of the economy where loss models do not exist, we will use historic values, sector-based surveys, and expert solicitations.