Flood Risk Assessment (FRA) and Management Plans

Assessing and Managing Flooding Risks

The purpose of a Flood Risk Assessment (FRA) is to identify and quantify the risk of flooding to people, property and infrastructure. Following the flood risk assessment, if the identified risk is unacceptable, we prepare a Flood Risk Management Plan (FRMP) that outlines cost-effective and sustainable long-term management strategies. 
FRAs can be undertaken at regional, strategic or site-specific scales. 

The assessment of the flood risk follows a specific sequence of steps:

• Calculate the extent and frequency of flooding
• Determine the economic, social and environmental impact of flooding, including the safety and health impacts
• Outline the existing risk and potential future risk resulting from changes in climate and human activity
• Flood Maps are used to indicate flood extents, depths and hazards for a range of probabilities (return periods). Determination of economic damages are typically calculated from databases of historical costs of flooding

The FRMP will usually consider a suite of measures:

• Adaptation planning
• Emergency response planning
• Flood forecasting and warning
• Individual property protection
• Land use management 
• Maintenance of river channels 
• Natural water retention measures
• Promotion of individual and community resilience
• Structural measures such as flood defence walls and embankments
• Sustainable planning and development management
• Sustainable Urban Drainage Systems (SUDS)
• Voluntary Home Relocation

Certain options will address the existing flood risk, e.g., structural measures, whereas others are suitable for managing future flood risk only, e.g. sustainable planning and development. All feasible options are considered in detail through a multi-criteria analysis that considers the technical, environmental, and economic aspects of each, allowing a preferred option to be chosen from the results.