Determining Community Similarity

We know from our research that communities seeking to address coastal hazard risks often look to their peers when exploring which options might work best for them. However, this raises two questions: which communities have already taken steps to address similar exposures, and how similar are they to the target community? Identifying these peer communities is where Resilient-C can help.

Our database includes information about hazard exposure, community vulnerability, and the actions communities across Canada have undertaken to address coastal hazard risks (Figure 1). With this information, the platform calculates community similarity and identifies those communities that most closely match the target community. This information can be refined by filtering for specific hazard exposures or the types of actions taken to address hazard risk and increase resiliency.

Figure 1: The key datasets collected and used by Resilient-C include hazard exposure, community
vulnerability profiles, and risk reduction actions — **Figure 1:** The datasets collected and used by Resilient-C when determining peer communities

Hazard Vulnerability Similarity Index

Our team developed a set of 25 hazard similarity indicators that the platform uses to profile each of the communities in our database. These indicators are broken into five capitals, addressing a specific aspect of community vulnerability and resilience: economic, social, built environment, natural environment, and institutional.

We then developed an equation to help us measure the similarity between any two communities in our database using these 25 indicators, called the Hazards Vulnerability Similarity Index (HVSI ). The platform uses the HVSI to calculate a similarity value between zero and one for each pair of communities in our dataset. More similar communities have values closer to one, while less similar communities have values closer to zero. In most cases, a value of 0.75 or above is deemed similar enough to be a potential "peer" community (Figure 2).

The Community Similarity Map

This information is compiled for users on the Similarity Map, accessible by clicking on the "Find Similar Communities" link on the sidebar from any community profile. The target community is indicated on the map with a black marker. Communities with high similarity are shown with markers in orange and red, while less similar communities are shown in blue (Figure 3). The Top Communities bar, located along the side or bottom of the map, quickly identifies the top ten most similar communities for the target community.

Figure 3: The Resilient-C similarity map for Courtenay, British — **Figure 3:** Similarity map for Courtenay, British Columbia

Filtering for Hazard Exposure or Action Types

Resilient-C's similarity map allows users to quickly identify those communities that are most likely to be peers for a given target community. By default, the similarity map uses all 25 vulnerability indicators. While this is useful, it can often be helpful to narrow down a search to those communities exposed to specific coastal hazards or that have undertaken specific action types. Therefore, the similarity map allows users to adjust filters to help identify peer communities that match a specific set of criteria (Figure 4).

Figure 4: The Resilient-C similarity map filters interface — **Figure 4:** Similarity map filters interface

By selecting the criteria that best match your community's needs, it is possible to identify those peer communities from across the country that best matches your own. You can examine how peer communities compare to your own and begin exploring your peers' actions to address coastal hazards or climate change adaptation.