Coastal Vulnerability Index Model
Assessing the vulnerability of the coasts to climate stressors
Coastal vulnerability refers to a combination of physical, environmental, social, and economic contributors' impacts. The coastal vulnerability assessment implies the integration of multiple quantitative and qualitative data to describe the status of a system or community to an imposed hazard.
Coastal systems are prone to coastal hazards and under constant interaction with a different natural and social environment. Vulnerability assessment increases the understanding of a complex coastal system.
Why Coastal Vulnerability Assessment?
Coastal Vulnerability assessments answer questions about existing conditions of the assets; spatial extend of the impacts, exposure to climate change stressors, demonstrates the limit of the system to cope with the consequences. It prepares the region for climate change planning.
Coastal vulnerability assessment support climate and coastal management policy development.
CT Coastal Vulnerability Index
UConn CIRCA developed an index-based spatial model to Connecticut's coastal vulnerability
The main aim of the model is to identify the vulnerable receptors in the region and localize vulnerable hot spot areas.
The model provides relative vulnerability maps that allow the prioritization of more vulnerable areas. It targets different climate-related impacts in the examined region and supports the identification of suitable areas for infrastructures and economic activities and places to increase resiliency.
Multi-scale assessment
Coastal Vulnerability Index model is open-source. It allows users to download the layers and create their own sector and scale specific vulnerability to climate stressors.
Methodology
The collected and gridded data layers are ordered from their highest to lowest values in the coastal boundary. The values are divided into five quantiles (0-20% represents the lowest 20% of the dataset, whereas 80-100% represents the highest quantile of data). Each quantile is assigned a rank value to relatively allocate the vulnerability of the layer to the climate hazard (0-20% is assigned to 1 (very low), similarly, 80-100% is assigned to 5(very high)). Thus, the contributor layers are created.
The grid resolution of the model is 1 acre (200x200m).
Overlay of multiple contributor layers forms vulnerability layers. The root-square-mean of the each contributor layer in a specific grid generates the vulnerability index in that grid. The vulnerability layers presented demonstrates sea-level rise as a coastal stressor.
Methodology is developed from: Gornitz, Vivien. "Vulnerability of the East Coast, USA to future sea level rise." Journal of Coastal research (1990): 201-237.
Contributor Layers
Examining the contributor maps in different scales allows the overall impact of that contributor to the selected area.
For example, the average elevation of the CT coasts can represent moderate vulnerability, however, the average elevation index of New Haven is high.
Contributor Layers
Examining the contributor maps in different scales allows the overall impact of that contributor to the selected area.
For example, the average elevation of the CT coasts can represent moderate vulnerability, however, the average elevation index of New Haven is high.
The vulnerability layers are the overlay of the sea level rise and other contributors. The vulnerability of a specific subject with respect to sea-level rise is available.
The demonstrated layer is Erosion Vulnerability concerning sea-level rise. The contributor layers overlaid are sea-level rise, erosion susceptibility, shoreline erosion rate, soil drainage, impervious area.
Users can create specific vulnerability layers with respect to different climate stressors by overlaying the index-based layers.
The contributor layers overlaid to form vulnerability layers are assumed to have equal weight.
The coastal vulnerability index can be combined with the analytical hierarchical process (AHP) to incorporating judgement to specify the weights of used criteria. Thus, the vulnerability is also defined as a function of exposure, sensitivity, and adaptive capacity to allow weighting flexibility to involve citizen science.
- Exposure is the degree of the stress that the particular asset is going through with climate variability. Exposure includes the change, including magnitude and magnitude and frequency of extreme events.
- Sensitivity is the degree to which a built, natural, or human system will be impacted by changes in climate conditions.
- The potential impact is a combination of exposure and sensitivity in light of a climate hazard.
- Adaptive Capacity is the ability of a system to adjust to changes, manage damages, take advantage of opportunities, or cope with consequences.
Source for definitions: https://climatechangeresponses.biomedcentral.com/articles/10.1186/s40665-017-0030-y
The physical and climate exposure forms the total exposure in the area.
The physical exposure indicates the non-climate related environmental contributors that will increase the potential impact of climate vulnerability in the region. The climate exposure indicates the climate related contributors that will increase the potential impact of climate vulnerability in the region by changing the extreme event magnitude and frequency.
The decision criteria of exposure sub-layers can reflect the vulnerability of the coastal communities more accurately.
Similarly, sensitivity is divided into built, ecological and socio-economic sub-layers and adaptive capacity is divided to built and ecological sub-layers.
Coastal Vulnerability Index model allows:
- Multi-scale analysis
- Map representation
- Statistical distribution
- Changing base map layer and color of scale
- Overlay modeled flood scenarios
Index-based tools are useful to make a first assessment of the vulnerability of different coastal areas to climate change, and support adaptation planning and regional integrated coastal zone management strategies.
