Flooding in Cornwall 17 November 2010 in association with Segmented Line Convection

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A frontal system brought a period of intense rain to parts of Cornwall in the early hours of 17 November 2010, resulting in disrup-tion to road and rail networks and signifi-cant flooding in some towns and villages. Figure 1 shows a map of the area with rain-fall totals for this event. Around 250 proper-ties were damaged by floodwater in the worst affected areas around St Austell, Lostwithiel and Mevagissey, as was the Eden Project site (between St Austell and Luxulyan). Several landslides were also reported: one closed the Newquay to Par railway line and there was concern that a road bridge over the River Fowey at Lostwithiel would collapse at one point (Figure2). Rainfall totals for this event were not extreme, but it may be noted that water courses were reported as swollen in the week prior to the event, and the two-hour period of particularly heavy rain on this night followed a longer period of moderate to heavy rain. It is also likely, as news reports suggested, that some of the excess surface-water problems were caused by fallen leaves blocking drainage systems. The event does highlight the fact that some areas are more prone to flash flooding than others, such as where drainage capacity is constrained by the topography into narrow, relatively short and steep-sided, catchments – as seen also at Boscastle in August 2004 (Golding et al., 2005). The area of heavy rain also extended across Bodmin Moor and adjacent river catchments, and less serious flooding was reported in other parts of Cornwall, as well as in west Wales. There were strong and gusty southerly winds

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