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Coastal Flooding Hazard Use Case

The island communities off the coast of Maryland often face coastal flooding and other hazards. The islands are very remote; in some cases, there may be only one way to travel to and from an island. Those who may need to evacuate during a flood event are at higher risk. The Maryland Department of Emergency Management (MDEM) used Risk Index data to identify and prioritize communities with limited emergency access. MDEM will focus on these communities for evacuation and other emergency response planning efforts.  


  • The MDEM Preparedness Branch wanted to identify communities with limited transportation access and high coastal flood risk. Having these data would help MDEM assist those most at risk and remote. 
  • The isolated nature of these communities creates unique challenges. These challenges have led to gaps in assistance that MDEM is looking to address. These communities require specific planning scenarios to prepare for coastal flooding; a flood event could cut off the bridges that connect them to networks of aid. 
  • It is hard for the state to collect data on local hazard events because not all communities have the emergency management staff or resources to maintain databases. Data are key for MDEM to better understand coastal flood risks. This way, MDEM can help communities to reduce coastal flood risks. 


  • The MDEM Preparedness Branch worked with the Risk and Recovery Branch to find data sources on the island communities’ risk. They used the Expected Annual Loss and annualized frequency for Coastal Flooding from the National Risk Index. This data analysis showed the branches which communities faced the most coastal flood risk.   
  • The branches merged the Risk Index Coastal Flooding data with transit, social vulnerability and resilience data. This helped them find the most remote and at-risk island areas. The data showed four communities with limited bridge, ferry and airfield access: St. George Island, Cobb Island, and Smith Island, and Stevensville.  
  • The Preparedness Branch now has an initial list of islands that are the most at risk to coastal flooding and have the fewest ways to evacuate. The data will serve as a basis for emergency response planning and future outreach. This way, rescuers have the information and training they need to help these communities during a coastal flooding event.  

Key Takeaways

  • Data help with making decisions to allot finite resources. The MDEM Preparedness Branch combined Risk Index Coastal Flooding data with other Maryland infrastructure data to find communities with the most vulnerability. Having this information is a valuable way to prioritize efforts with finite time and resources; it helps MDEM focus planning and outreach on those that need it most. 
  • The FEMA National Risk Index fills data gaps. The Risk Index provides data at the local level for communities with few resources and mapping capacity. For places where there were no local risk data, the state could use the Risk Index to give a baseline of coastal flood risk.  
  • FEMA National Risk Index data can be tailored to meet community needs. The data from the Risk Index are easily paired with those from other data sources. The MDEM Risk and Recovery Branch was able to choose what data worked best to reach its goal. Now, the Preparedness Branch has a unique analysis. It can use this to develop evacuation and emergency response plans to increase community resilience.