The multi-agency flood plan is a major component of the response to significant flooding in Avon and Somerset. In the document, reference to risk implies a function of both the chance or likelihood of a hazard becoming reality and the consequences or impact of that occurrence. The consequence will depend upon the exposure of people and property to the hazard and their respective vulnerability to harm. An outline of the potential risk to flooding in Avon and Somerset from the different sources of flooding can be found here.

Due to climate change, both the chance and consequence of flooding are increasing. Factors of climate change, such as sea level rise, more frequent and higher storm surges, increased winter rainfall, and more intense summer rainfall will add to existing risk where it may not be possible to improve fixed defences sufficiently to maintain or raise protection standards.

Floods are generally natural events that are the result of either excessive rainfall leading to pluvial flooding, rivers overflowing their banks, or from tidal storm surges on the coast or in estuaries. Floods cause death and damage only because human activity takes place in areas such as river valleys or estuaries where floodwater spreads. In urban areas, man made drainage systems may have inadequate capacity or become blocked also leading to flooding.

To limit both the chance and consequences of flooding, the customary response has been to construct fixed, raised defences in the form of walls or embankments or other structural measures such as bypass channels or pumped drainage systems. These do not eliminate the chance of flooding entirely. They may though, lead to a false sense of security or complacency in those living or working in the defended areas, who would be unprepared for a flood should one occur.

Contents of the Plan

The multi-agency flood plan works in close proximity to the Environment Agency warning mechanisms for flooding. Included in the plan are the different stages of flood warning and the relative activation and response procedures that follow. A diagram and table of these procedures can be found here.

Also included in the plan are;

• Communications Plan
• Command and Control procedures
• An outline of vulnerable people
• Key Infrastructure
• Evacuation and Sheltering
• Recovery
• Training and Exercising