Pluvial extreme event risk appraisal techniques with recent applications in Ireland and the UK

Pluvial flooding is defined as flooding from rainfall generated overland flow before the runoff enters any watercourse or sewer. It is usually associated with high intensity events but can also occur with lower intensity rainfall where ground is saturated, developed or otherwise has low permeability resulting in overland flow and ponding in topographical depressions. rainage systems and surface watercourses may be completely overwhelmed. Recent examples include the Summer 2007 floods in Ireland and England where pluvial flooding has been a major contributing factor. Identifying areas potentially at risk from pluvial flooding is a requirement of the Floods Directive,particularly in relation to the Preliminary Flood Risk assessments which, as a first stage involves, high level screening of a catchment to determine all sources of potential flood risk.