Types of Flooding

Types of Flooding

Arlington experiences three types of flooding: Riverine, coastal and interior flooding.  

• Riverine flooding occurs when the stream channel is not able to contain water flowing downstream from the land areas around the stream.
• Coastal flooding occurs in areas affected by high tides or storm surge. In Arlington, coastal flooding is a concern in lower Four Mile Run and along the Potomac River waterfront.
• Interior flooding (flash flooding, urban flooding) occurs when rainfall overwhelms the capacity of soil and local drainage systems. 

Riverine and coastal flood risk are mapped and regulated by the Federal Emergency Management Agency (FEMA) and local governments through mapping of FEMA floodplains.

However, damage from recent flood events in Arlington County has largely been caused by interior flooding, which is outside of FEMA floodplains. The areas vulnerable to interior flooding are often low lying areas where streams were buried during Arlington’s early development (prior to any stormwater regulation). As a result, many residents and businesses impacted by interior flooding events did not realize they are in areas at risk of flooding.

Learn about your flood risk from all three types of flooding by viewing the VA DCR FATHOM Flood Risk Map.  Knowing your flood risk is the first step to flood protection.